HSVN is described in the report as a vascular tumour that behaves in a largely indolent fashion, meaning it tends to follow a slow, non-aggressive course. Its malignant potential, however, remains uncertain, which places clinicians in a difficult position when deciding how aggressively to investigate and manage it. The authors highlight that this diagnostic and management challenge is particularly relevant in a transplant recipient, a setting in which such a finding has not previously been reported.

A central theme of the case report is the diagnostic challenge the tumour poses. HSVN must be separated from hepatic angiosarcoma, a malignant vascular tumour of the liver. The authors note that HSVN lacks the marked cytologic atypia, the abnormal cellular appearance under the microscope, that characterizes angiosarcoma. The distinction also rests on immunohistochemical testing: unlike hepatic angiosarcoma, HSVN does not demonstrate diffuse overexpression of the proteins p53, GLUT1, or c-Myc. These differences in cellular appearance and protein expression form the basis on which pathologists can tell the two entities apart.

The report highlights the management considerations that follow from this diagnostic picture. Because the tumour’s behaviour is indolent but its malignant potential is not fully defined, the authors present the case as an illustration of the diagnostic challenges and management considerations that arise when such a lesion is found in a liver allograft. The keywords accompanying the article, which include CMV, EBV, CT, and H&E, point to the diagnostic toolkit of imaging, histological staining, and viral screening that surrounds the evaluation of lesions in transplant patients, although the abstract itself does not report specific findings for these investigations.

The significance of the case lies in expanding the known settings in which HSVN can occur. Documenting it in an allograft adds transplant recipients to the population in which pathologists and hepatologists may need to consider the diagnosis. The authors state that all claims expressed in the article are solely those of the authors and do not necessarily represent those of their affiliated organizations or the publisher. The report was received on 2 August 2026 and accepted on 22 September 2026, and the final formatted version is set to be published as an open-access article under a Creative Commons Attribution licence.

Subject of Research: Hepatic small vessel neoplasm occurring in a liver transplant recipient

Article Title: Hepatic small vessel neoplasm, a first case report in a liver transplant recipient

Article References: Ahmad, A. A. Y., Craughwell, M., Clarke, L., Nolan, N., Dillon, A., & Galvin, Z. (2026). Hepatic small vessel neoplasm, a first case report in a liver transplant recipient. Frontiers in Gastroenterology, 5, Article 1956520. https://doi.org/10.3389/fgstr.2026.1956520

Image Credits: AI Generated

DOI: 10.3389/fgstr.2026.1956520

Keywords: hepatic small vessel neoplasm, liver transplant, vascular tumour, angiosarcoma, case report, hepatology, immunohistochemistry, liver allograft, p53, GLUT1, c-Myc, Frontiers in Gastroenterology

A research team has now reported a systematic attempt to change that. Their strategy centered on a specific weakness in c-Myc biology: the protein exerts its oncogenic activity primarily by pairing with a partner transcription factor called Max. The resulting c-Myc–Max heterodimer recognizes the canonical E-box DNA sequence, CACGTG, and modulates the expression of downstream target genes through either transcriptional activation or repression. Because this protein–protein interaction sits at the heart of c-Myc-driven tumorigenesis, disrupting the dimerization interface offers a way to block c-Myc without needing to grip the protein itself. Prior work supports the concept — compound B13, for example, has been shown to block the c-Myc/Max interaction and suppress primary colorectal tumor growth in xenograft mouse models — but the field still lacks potent, optimized inhibitors developed specifically for colorectal cancer.

The discovery workflow began in silico. Using the Surflex docking algorithm within the Sybyl-X2.1 software package, the team targeted the c-Myc/Max complex structure deposited in the Protein Data Bank under the identifier 1NKP. They selected a structurally well-characterized binding pocket composed of Leu917, Phe921, and Lys939 on c-Myc, together with Arg212, Arg215, Asp216, Ile218, Lys219, Phe222, and Arg239 on Max — the same interface strategy reported in earlier studies. Candidate molecules came from the ChemDiv database, a library of 1.6 million commercially available compounds with purity above ninety-five percent. Before any docking took place, the library was filtered through Lipinski’s Rule of Five, which imposes limits on molecular weight, hydrogen bond donors and acceptors, and lipophilicity to exclude non-drug-like molecules. That first round of screening retained about 1.06 million compounds.

The screening then narrowed the field in stages. A low-precision docking pass rapidly assessed the binding affinity of the 1.06 million survivors against the target pocket, and only the top one percent — roughly 10,600 compounds — advanced. The team then re-docked those candidates under high-precision, standard parameters and kept the top 500 ranked molecules. Finally, an integrated strategy combining docking score ranking with structural clustering analysis selected four compounds for commercial purchase: 6069–0336, C201–1652, D144–0281, and E959–1030, with docking scores of 8.263, 8.695, 8.874, and 9.036 in units of −log Kd, respectively. Nuclear magnetic resonance spectra confirmed the identity of the four purchased compounds, and the entire funnel — from 1.6 million molecules to four testable hits — illustrates how modern virtual screening can compress an otherwise impossible chemical search into a manageable bench experiment.

The four hits then faced living cells. The team tested them against SW480 and Caco-2 colorectal cancer cell lines, both well characterized and both known to depend on c-Myc signaling for proliferation and survival, using a CCK-8 viability assay across concentrations from one to twenty micromolar over forty-eight hours. Three of the four compounds — C201–1652, D144–0281, and E959–1030 — significantly reduced the viability of both cell lines in a dose-dependent manner, while 6069–0336 showed comparatively weak cytotoxicity. Quantitatively, E959–1030 was the most potent, with an IC50 of 4.81 micromolar in SW480 cells and 11.34 micromolar in Caco-2 cells, followed by C201–1652 at 9.51 micromolar in SW480 and D144–0281 at 16.98 and 12.94 micromolar in the two lines, respectively. All three active compounds showed minimal cytotoxicity toward HEK293T cells within the tested range, whose IC50 values exceeded twenty micromolar, yielding selectivity indices above 1.0. Benchmarking against the classic c-Myc inhibitor 10,058-F4, whose IC50 exceeded fifty micromolar in both cancer lines, the screened compounds displayed superior antiproliferative potency.

Apoptosis assays added a second layer of evidence. Defective apoptotic signaling is what allows cancer cells to evade cell cycle arrest and proliferate uncontrollably, so compounds that restore programmed cell death are considered reliable candidates in anti-tumor drug development. Flow cytometry using an annexin V-APC/7-AAD detection kit showed that C201–1652, D144–0281, and E959–1030 were significantly more potent than 6069–0336 at inducing apoptosis in SW480 cells, and all three effectively promoted apoptosis in Caco-2 cells as well. These effects occurred at low toxic doses. The authors caution, however, that HEK293T is an immortalized transformed cell line, so the observed selectivity reflects only preliminary in-vitro safety relative to that reference line and cannot be extrapolated to primary normal colon epithelial cells.

The mechanistic experiments produced the study’s most striking finding. Western blot analysis revealed that D144–0281 and E959–1030 significantly downregulated c-Myc protein levels in both SW480 and Caco-2 cells, consistent with the obvious suppression produced by the positive control 10,058-F4. Yet quantitative PCR showed no significant change in c-Myc mRNA levels in either cell line, indicating that the compounds do not directly regulate c-Myc transcription but instead appear to affect the protein post-transcriptionally — a pattern the authors note mirrors the small-molecule inhibitors MYCMI-7 and MY05, which trigger c-Myc protein destabilization and degradation without obvious changes in transcript levels. Dual luciferase reporter assays, in which HEK293T cells were transfected with a c-Myc expression plasmid, an MYC response element-luciferase reporter, and a Renilla reference plasmid, then demonstrated that D144–0281 and E959–1030 suppressed c-Myc-driven transcriptional activity in a dose-dependent manner, while C201–1652 showed no obvious inhibitory effect. GST pull-down assays using recombinant GST-c-Myc and His-Max proteins further indicated that high doses of D144–0281 and E959–1030 interfered with the physical interaction between c-Myc and Max.

Molecular dynamics simulations then stress-tested the predicted binding. The docked conformations served as starting structures for 200-nanosecond simulations in Amber18, with systems solvated in TIP3P water, heated from zero to 300 kelvin over 100 picoseconds, and run at a two-femtosecond time step. Root mean square deviation analysis showed all systems fluctuating between two and five angstroms, with average values of 4.1 angstroms for the apo-protein, 4.6 angstroms for the c-Myc/Max–D144–0281 complex, and 2.9 angstroms for the c-Myc/Max–E959–1030 complex; both ligand-bound systems stabilized within ten nanoseconds. Root mean square fluctuation analysis revealed that significant movements occurred mainly at the protein termini, far from the binding site, while residues at the active center fluctuated below two angstroms. MM/GBSA calculations yielded binding free energies of −40.72 kilocalories per mole for D144–0281 and −32.39 kilocalories per mole for E959–1030, both indicating favorable and spontaneous interactions. Energy decomposition showed D144–0281 binding mainly through van der Waals contacts with the hydrophobic region, engaging Leu917, Lys918, Phe921, Lys939, and Leu943 on c-Myc plus Ile218, Lys219, Phe222, and Arg239 on Max, whereas E959–1030 relied predominantly on electrostatic interactions and formed a stable hydrogen bond with the side chain of Arg239 on Max.

Virtual ADME profiling with SwissADME painted a mixed but encouraging drug-likeness picture. D144–0281 has a molecular weight of 443.45 grams per mole and E959–1030 weighs 390.52 grams per mole, both within the accepted range for oral agents, and both compounds are predicted to show high gastrointestinal absorption, zero Lipinski violations, and a bioavailability score of 0.55. Both are also predicted to cross the blood-brain barrier — a property the authors flag as a potential liability rather than purely an advantage, since it raises the risk of off-target central nervous system exposure. Metabolic profiling identified distinct safety concerns: D144–0281 inhibits multiple cytochrome P450 isoforms, elevating the risk of drug-drug interactions, while E959–1030 inhibits only CYP2D6 and CYP3A4, carrying a relatively lower metabolic interaction risk.

The authors are candid about what the study does and does not prove. The docking was based on an apo protein crystal structure with no co-crystallized ligand, so conventional redocking validation was impossible, and the Surflex scoring function provides only relative binding affinity estimates rather than absolute binding free energies; the MD simulations support the stability of the predicted complexes, but the binding poses remain putative and require further experimental validation. The GST pull-down results demonstrate disruption of the c-Myc/Max interaction but do not constitute direct biophysical evidence of physical binding between the compounds and either protein — surface plasmon resonance assays will be needed to confirm direct target engagement. The work was restricted to in-vitro characterization without prior medicinal-chemistry optimization, so solubility, metabolic stability, and pharmacokinetic profiles remain unknown, and no xenograft assays or combination studies with clinical colorectal cancer chemotherapeutics were performed. Still, by occupying an identical binding pocket of the c-Myc/Max complex, interfering with the heterodimer, suppressing c-Myc protein post-transcriptionally, and blocking downstream transcriptional activity, D144–0281 and E959–1030 establish a basis for further preclinical evaluation of c-Myc/Max inhibitors for colorectal cancer.

Subject of Research: Discovery of c-Myc/Max complex inhibitors for colorectal cancer through virtual screening and in vitro validation

Article Title: Integrated virtual screening and in vitro evaluation identify potential c-Myc/max complex inhibitors for colorectal cancer

Article References: Miao, Z., Ge, G., Chen, A., Liu, X., Kuang, Y., & Cui, H. (2026). Integrated virtual screening and in vitro evaluation identify potential c-Myc/max complex inhibitors for colorectal cancer. Results in Chemistry, 31, Article 103982. https://doi.org/10.1016/j.rechem.2026.103982

Image Credits: AI Generated

DOI: 10.1016/j.rechem.2026.103982

Keywords: colorectal cancer, c-Myc, Max, virtual screening, molecular docking, protein-protein interaction, apoptosis, molecular dynamics, MM/GBSA, ADME, drug discovery, in vitro

NDUFS1 is the largest subunit of complex I in the mitochondrial electron transport chain, where it is essential for normal complex I function. The chain supports oxidative phosphorylation, the process by which mitochondria generate much of the cellular energy used for growth and division. The study notes that cancer cells often favor glycolysis even when oxygen is available, a pattern commonly called the Warburg effect, but mitochondrial oxidative phosphorylation can remain intact or become elevated in particular tumor contexts. Breast cancer, the authors write, is heterogeneous in its reliance on mitochondrial metabolism, making it important to determine whether particular respiratory components contribute to disease progression.

The investigators first examined NDUFS1 expression in publicly available breast cancer datasets and in tissue samples collected at Kaohsiung Medical University Hospital in Taiwan. NDUFS1 messenger RNA levels were higher in breast tumors than in normal breast tissue in the Oncomine analysis. An analysis of the harmonized TCGA-TARGET-GTEx dataset also showed higher expression across breast cancer subtypes, compared with 178 normal breast samples. Immunohistochemical analysis of hospital specimens showed higher NDUFS1 protein expression in cancer tissue than in normal tissue and an additional increase in later-stage tumors. In the hospital cohort, high NDUFS1 expression was significantly associated with stage, T stage and lymph-node metastasis; adjusted odds ratios were 3.36 for T2–T4 versus T1 disease and 6.34 for N1–3 versus N0 disease.

Survival analyses produced a parallel clinical pattern. In publicly available breast cancer microarray data, patients with high NDUFS1 messenger RNA expression had significantly poorer recurrence-free and overall survival. The same association appeared in overall-survival data from TCGA-BRCA. Multivariable Cox analysis indicated that high NDUFS1 expression remained independently associated with worse overall survival after adjustment for age, stage and breast cancer subtype, or for age, TNM stage and receptor status. These observations are associations rather than evidence that NDUFS1 directly causes poor outcomes, and the study combined several different datasets and a single-center tissue cohort.

Functional experiments were performed in two human breast cancer lines: ER-positive MCF-7 cells, used as a luminal A model, and triple-negative MDA-MB-231 cells. Reducing NDUFS1 with short hairpin RNA significantly reduced XTT-measured proliferation, migration and invasion in both lines. The opposite effects occurred when NDUFS1 was overexpressed. In MCF-7 cells, NDUFS1 knockdown also reduced tumorsphere formation and lowered the expression of KLF4, c-Myc and SOX2, proteins associated with stemness-related features. NDUFS1 overexpression increased c-Myc in both cell lines. The association also appeared in patient material: NDUFS1 expression correlated positively with MYC messenger RNA in TCGA-BRCA tumors and with c-Myc protein in immunohistochemical measurements.

Respiration measurements indicated that these effects were connected to mitochondrial function. NDUFS1 knockdown reduced basal oxygen consumption, oxygen consumption rate, ATP production, maximal respiration and spare respiratory capacity in MDA-MB-231 and MCF-7 cells. Overexpression increased basal oxygen consumption and ATP production. Extracellular acidification also declined after knockdown, rather than rising as a compensatory sign of increased glycolysis. To test whether respiration contributed to the malignant phenotypes, the researchers used metformin, a mitochondrial complex I inhibitor. At a concentration reported not to affect cancer-cell viability, metformin reversed the increases in proliferation and migration caused by NDUFS1 overexpression. This supports a functional role for complex I activity, although metformin can also affect other signaling pathways and the study did not establish that the drug acted exclusively through NDUFS1.

Bulk RNA sequencing of MDA-MB-231 cells after NDUFS1 knockdown was used to search for a mechanism connecting respiration to the observed behaviors. Three genes associated with migration, stemness or proliferation—PROX1, MEF2C and WNT5A—were reduced after knockdown, with PROX1 selected for further analysis because its protein level changed consistently with NDUFS1 in both breast cancer lines. NDUFS1 and PROX1 expression were positively correlated in TCGA-BRCA data and in tumor immunohistochemistry. In cells, reducing PROX1 lowered c-Myc, whereas reducing c-Myc did not lower PROX1, placing PROX1 upstream of c-Myc in the proposed pathway. Knockdown of either protein increased p21, while metformin reversed the NDUFS1-associated increases in PROX1 and c-Myc. The authors therefore proposed an NDUFS1–PROX1–c-Myc–p21 axis, but acknowledged that the precise metabolic link remains unresolved.

Several possible mechanisms were considered. Mitochondrial oxidative phosphorylation can affect metabolite availability and histone acetylation, and reduced citrate production could theoretically contribute to decreased PROX1 expression. Changes in reactive oxygen species and redox-sensitive pathways were another possibility, but the direction of known effects in those pathways did not fully match the observations. Ferroptosis, an iron-dependent form of programmed cell death associated with lipid peroxidation, was also raised as a potential contributor because NDUFS1 participates in iron–sulfur cluster biology. The authors explicitly identified this as a question for future experiments rather than a demonstrated mechanism. They likewise noted that metformin may influence AMPK–mTOR, TGF-β and prostaglandin-related signaling, so the cell experiments do not prove that every effect runs through the PROX1–c-Myc pathway.

The findings were extended to a syngeneic orthotopic model using luciferase-expressing 4T1 mouse breast cancer cells implanted in the mammary fat pads of BALB/c mice. Ndufs1 knockdown reduced proliferation, migration, invasion and tumorsphere formation in the cells before implantation. Mice receiving the knockdown cells developed tumors with significantly lower bioluminescence, final volume and weight than controls. NDUFS1, PROX1 and c-Myc protein levels were lower in the resulting tumors, and tumor-level NDUFS1 expression correlated with both PROX1 and c-Myc. No obvious metastases were detected by bioluminescence imaging, which the authors said could reflect an immune response to the xenogeneic luciferase reporter and therefore limited metastasis assessment.

Giving the complex I inhibitors metformin or rotenone intraperitoneally five times per week for four weeks reduced bioluminescence, tumor volume and tumor weight in control mice to levels comparable to those in the Ndufs1-knockdown group. Immunohistochemistry also showed lower NDUFS1, PROX1 and c-Myc in treated tumors. These mouse experiments support a tumor-suppressing effect of complex I inhibition in this model, but they do not demonstrate clinical efficacy in people. The study itself cites a randomized trial involving 3,649 patients that did not find a benefit from metformin for invasive disease-free survival in breast cancer. NDUFS1 expression may eventually help identify metabolically high tumors for appropriately designed trials, but biomarker-guided treatment remains a hypothesis requiring prospective testing.

Overall, the study provides mechanistic and preclinical evidence that NDUFS1 supports breast cancer malignancy by sustaining mitochondrial oxidative phosphorylation and enhancing PROX1–c-Myc signaling. Its strongest links are the consistent changes in tumor and cell phenotypes after NDUFS1 manipulation, the respiratory measurements and the suppression of those effects by complex I inhibition. Important gaps remain: the study did not directly demonstrate that PROX1 and c-Myc are required for NDUFS1-driven proliferation, migration or invasion; it did not establish how reduced respiration alters PROX1; and it did not test the drugs’ effects on breast cancer metastasis in vivo. The work therefore identifies NDUFS1 as a candidate biomarker and therapeutic vulnerability, rather than a ready-made target or a replacement for established breast cancer treatment.

Subject of Research: Preclinical investigation of NDUFS1-driven mitochondrial respiration and breast cancer progression

Article Title: NDUFS1 promotes malignant breast cancer behaviors through enhancement of mitochondrial respiration and PROX1/c-Myc signaling

Article References: Wang, Y.-Y., Chen, P.-Y., Vinzons, L. U., Tseng, C.-H., Chen, Y.-K., Chu-Sung Hu, S., Lo, S., Hou, M.-F., Wu, C.-H., Chen, Y.-C., & Yuan, S.-S. F. (2026). NDUFS1 promotes malignant breast cancer behaviors through enhancement of mitochondrial respiration and PROX1/c-Myc signaling. iScience, 29(11), Article 117942. https://doi.org/10.1016/j.isci.2026.117942

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DOI: 10.1016/j.isci.2026.117942

Keywords: breast cancer, NDUFS1, mitochondrial respiration, oxidative phosphorylation, PROX1, c-Myc, complex I inhibition, metformin, tumor growth, promotes, malignant, breast

Oculodentodigital dysplasia, or ODDD, is an ultra-rare autosomal dominant disorder caused by germline variants in GJA1. Patients typically show a pleiotropic constellation of features affecting the eyes, teeth, digits, and sometimes the central nervous system, with severity varying dramatically even within the same family. Connexin 43 is the most ubiquitously expressed connexin in the human body, forming gap junction channels that allow direct cytoplasmic exchange between adjacent cells. But the protein’s long C-terminal tail also does channel-independent work, physically associating with signaling partners such as β-catenin and various kinases. It is this second, scaffolding role that the new research places at the center of the disease mechanism.

The team, led by researchers at Peking Union Medical College Hospital and Children’s Hospital of Soochow University, recruited two families with classic ODDD presentations. Proband 1, a young girl, displayed short palpebral fissures, hypoplastic alae nasi, sparse hair, bilateral syndactyly of the fourth and fifth fingers, and dental anomalies including microdontia and enamel hypoplasia. Her affected younger brother carried the same craniofacial and hand phenotype, while their mother showed only mild bilateral brachydactyly of the fifth fingers—a striking example of intra-familial variability. Proband 2 presented similar features along with syndactyly of the toes, and whole-genome sequencing revealed his variant arose de novo, absent from both clinically healthy parents. Sanger sequencing confirmed heterozygous missense variants, c.253G>C in Family 1 and c.605G>A in Family 2, both segregating perfectly with disease status.

What makes the study unusual is its reliance on primary patient-derived cells rather than engineered model systems. The researchers cultured skin fibroblasts from both patients and mesenchymal stromal cells, or MSCs, harvested from discarded surgical bone and skin tissue collected during syndactyly release and corrective osteotomy procedures. Controls came from age- and sex-matched pediatric patients undergoing hand trauma surgery at the same anatomical site, with whole-genome sequencing used to exclude any pathogenic variants in known disease genes. Flow cytometry confirmed the MSC identity, with cells positive for CD90, CD105, and CD73 and negative for CD45, meeting the International Society for Cellular Therapy minimal criteria.

RNA sequencing on patient fibroblasts and MSCs revealed a transcriptional landscape split cleanly in two. Downregulated gene sets were dominated by Wnt signaling, extracellular matrix–receptor interaction, osteoblast differentiation, DNA replication, and cell cycle regulation. Upregulated sets lit up with inflammatory response genes, cytokine-mediated signaling, JAK-STAT signaling, tumor necrosis factor response, and ECM structural constituents. The team then validated these patterns at the protein level using RT-qPCR, Western blotting, immunofluorescence, and ELISA. In both fibroblasts and MSCs, mRNA levels of canonical Wnt targets—AXIN2, CCND1, PCNA, and c-MYC—fell sharply. Protein levels of Cx43, β-catenin, and IκBα dropped in parallel, while the ratio of phosphorylated p65 to total p65 rose, a signature of NF-κB pathway activation.

The inflammatory profile that emerged is the study’s most surprising finding. Interleukin-6 expression and secretion surged in patient cells, yet CXCL8—better known as IL-8—was paradoxically and significantly reduced, despite NF-κB being switched on. Interferon-stimulated genes MX1 and IFIT1 were simultaneously elevated. The researchers traced this uncoupling to c-MYC, the Wnt-dependent transcription factor whose loss appears to lift normal repression on MMP3 while simultaneously starving CXCL8 of a required activator. MMP3, or stromelysin-1, is a matrix metalloproteinase that degrades components of the extracellular matrix, and its abnormal upregulation points to excessive ECM remodeling—a process that could plausibly underlie the tissue fusion seen in syndactyly, though the authors caution that this connection remains speculative and requires in vivo validation.

Functional assays confirmed the molecular story has real cellular consequences. Transwell migration assays showed patient fibroblasts and MSCs crossed basement membranes at markedly reduced rates, while EdU incorporation revealed suppressed proliferation. These defects align with the coordinated downregulation of CCND1, PCNA, and c-MYC, key regulators of the G1/S cell cycle transition, suggesting GJA1 deficiency stalls cells before they enter DNA synthesis. Differentiation assays added another layer: patient MSCs showed compromised osteogenic capacity, with reduced alkaline phosphatase activity and diminished Alizarin Red S mineralization, alongside aberrantly enhanced adipogenic potential measured by Oil Red O staining. This lineage shift mirrors the classical biology of Wnt signaling, which normally maintains MSC stemness, promotes bone formation, and suppresses fat cell differentiation—offering a cellular explanation for the bone hypoplasia seen in ODDD patients.

To establish causality rather than mere correlation, the team ran bidirectional genetic interventions. Knocking down GJA1 with siRNA in normal control cells, reducing expression to roughly the level seen in patient cells, faithfully reproduced the entire patient phenotype: Wnt suppression, the IL-6-high/CXCL8-low inflammatory bias, elevated MMP3, impaired migration, and skewed differentiation. Conversely, overexpressing wild-type connexin 43 in patient cells substantially reversed these defects, restoring IκBα levels, reducing p65 phosphorylation, suppressing MMP3, and rescuing migration. A second round of experiments isolated c-MYC’s role directly: silencing c-MYC in normal MSCs reproduced the CXCL8 collapse and MMP3 surge, while overexpressing c-MYC in patient MSCs rescued both, establishing c-MYC as a necessary and sufficient regulator of these two genes downstream of the GJA1/Wnt axis.

Pharmacological experiments then mapped the hierarchy of the pathway. Treating patient cells with CHIR99021, a selective GSK-3β inhibitor that activates canonical Wnt signaling, restored c-MYC expression, corrected the CXCL8 deficit, suppressed MMP3, reduced IL-6 secretion, and improved both migration and osteogenic differentiation. In contrast, a neutralizing antibody against IL-6 acted only on downstream readouts: it dampened the interferon response but failed to restore c-MYC, could not rescue CXCL8, and left MMP3 overexpression untouched. The combination of both agents produced the strongest overall rescue, simultaneously targeting the core upstream defect and the downstream inflammatory overactivation. The comparison makes a clear translational argument: blocking a single cytokine treats symptoms, but reactivating the Wnt/c-MYC axis addresses the disease’s root signaling failure.

The authors are candid about the study’s limits. Fibroblasts came from only two patients and MSCs from one, so transcriptomic findings are explicitly framed as exploratory, and technical replicates from a single donor cannot substitute for independent biological replicates. The researchers also could not perform promoter-reporter or chromatin immunoprecipitation experiments to demonstrate direct c-MYC binding at the CXCL8 or MMP3 promoters, again because of the scarcity of pediatric patient cells. Connexin 43’s broad expression in heart, brain, and skin means long-term neurological and cardiac follow-up of the two families is warranted, even though neither child currently shows overt deficits in those systems. Still, the work delivers a coherent new pathogenic framework for ODDD—one in which a broken gap junction protein silently rewires Wnt, NF-κB, and matrix remodeling all at once—and it nominates Wnt activation, rather than isolated cytokine blockade, as the therapeutic strategy most worth pursuing in this rare and poorly understood disorder.

Subject of Research: Molecular mechanisms of GJA1-related oculodentodigital dysplasia in patient-derived fibroblasts and mesenchymal stromal cells

Article Title: GJA1 dysfunction suppresses Wnt/c-MYC signaling and promotes inflammatory imbalance and MMP3-associated ECM remodeling in fibroblasts and mesenchymal stromal cells from patients with ODDD

Article References: Tao, S., Zhao, B., Wang, X., Shen, X., & Zhao, X. (2026). GJA1 dysfunction suppresses Wnt/c-MYC signaling and promotes inflammatory imbalance and MMP3-associated ECM remodeling in fibroblasts and mesenchymal stromal cells from patients with ODDD. Frontiers in Cell and Developmental Biology, 14, Article 1959966. https://doi.org/10.3389/fcell.2026.1959966

Image Credits: AI Generated

DOI: 10.3389/fcell.2026.1959966

Keywords: oculodentodigital dysplasia, GJA1, connexin 43, Wnt signaling, c-MYC, NF-κB, MMP3, mesenchymal stromal cells, fibroblasts, rare disease, osteogenic differentiation, CHIR99021

The investigation began with a rigorous bioinformatic sweep of publicly available genomic data. The researchers mined The Cancer Genome Atlas HNSC dataset alongside four independent Gene Expression Omnibus datasets, namely GSE127165, GSE10121, GSE37991, and GSE30784, to identify genes consistently upregulated in tumor tissues compared with adjacent normal tissues. This cross-cohort analysis flagged 311 genes elevated in HNSCC, and among them, CCT2 stood out. Subsequent univariate Cox regression analysis across the GSE41613 and GSE42743 datasets narrowed the field to 45 common prognosis-associated genes, and CCT2 again emerged as a standout signal. Across all datasets examined, high CCT2 expression predicted poor prognosis, advanced clinical stage, and more aggressive tumor characteristics, painting a consistent statistical portrait of a gene that tracks with the worst outcomes in this disease.

Bioinformatics alone, however, can only suggest; the team turned to human tissue and laboratory models to confirm the biology. Immunohistochemistry performed on patient samples revealed robust CCT2 staining in tumor tissue relative to normal epithelium, and the same sections showed elevated Ki-67, a canonical marker of cellular proliferation, hinting that CCT2-expressing tumors were actively dividing. Western blotting on paired tumor and adjacent normal tissues from patient samples confirmed the protein-level overexpression, and the pattern held in cell culture: HNSCC cell lines including HSC-3, CAL-27, and SAS expressed far more CCT2 than normal epithelial cell lines such as HOEC and HIEC6. With the overexpression established at the transcript, protein, and tissue levels, the researchers moved to the critical question of causation.

The answer came from loss-of-function experiments that were strikingly decisive. When the researchers depleted CCT2 using knockdown techniques, HNSCC cells lost their ability to proliferate efficiently in vitro, and tumor growth slowed in vivo as well. Beyond proliferation, CCT2 depletion crippled the migratory and invasive capacities of the cancer cells, the very behaviors that enable metastasis and account for much of the lethality of head and neck cancer. Molecular profiling of these changes revealed a classic shift in epithelial-mesenchymal transition markers: the epithelial adhesion molecule E-cadherin increased, while the mesenchymal markers N-cadherin, vimentin, and Slug decreased. This signature indicates that CCT2 normally pushes cells toward the motile, invasive mesenchymal state, and its removal reverses that program, effectively locking tumor cells into a less aggressive identity.

Perhaps the most clinically consequential finding concerned cisplatin, the platinum-based chemotherapy that remains the backbone of treatment for advanced HNSCC despite frequent resistance. The researchers observed a positive correlation between CCT2 expression and cisplatin IC50 values across HNSCC cell lines, meaning that cells with more CCT2 required higher doses of the drug to die. When CCT2 was knocked down, cisplatin sensitivity rose both in cultured cells and in living tumor models, demonstrating that the effect is not an artifact of cell culture. This result positions CCT2 as a cell-intrinsic mediator of chemoresistance, offering a mechanistic explanation for why some head and neck tumors shrug off a drug that should, in principle, destroy them.

To understand how a protein chaperone subunit could exert such sweeping influence, the team dug into the signaling pathways enriched in CCT2-high tumors and found a strong signature of MYC-related activity. Co-immunoprecipitation experiments then demonstrated a direct physical interaction between CCT2 and c-Myc, the infamous transcription factor and oncogenic driver whose overexpression fuels growth in a wide range of cancers. The interaction proved functionally meaningful: cycloheximide-chase experiments, which track protein decay over time after blocking new protein synthesis, showed that CCT2 knockdown reduced c-Myc stability and shortened its half-life. In other words, CCT2 acts as a molecular bodyguard for c-Myc, protecting the oncoprotein from degradation and allowing it to accumulate to pathological levels inside tumor cells.

Downstream of this stabilization, CCT2’s influence on the cell cycle became apparent. The researchers found that CCT2 affected key cell-cycle regulators, including cyclin D1, encoded by CCND1, and cyclin E1, encoded by CCNE1, both of which drive the transitions that propel cells through division. To establish c-Myc as the functional mediator of CCT2’s effects, the team performed rescue experiments: when they overexpressed c-Myc in CCT2-deficient cells, cell-cycle progression was restored and the impaired migration and invasion were partially rescued. Conversely, knocking down c-Myc increased cisplatin sensitivity, mirroring the effect of CCT2 depletion itself. Together, these experiments sketch a coherent pathway in which CCT2 stabilizes c-Myc, which in turn orchestrates the cell-cycle programs and aggressive behaviors that define advanced HNSCC.

The study then uncovered an even more unsettling dimension of CCT2 biology, one that extends beyond individual cells to entire tumor populations. The researchers identified apoptotic vesicles, or apoVs, as vehicles for transferring chemoresistance between neighboring tumor cells. ApoVs released from cisplatin-treated HNSCC cells were found to contain CCT2, and recipient tumor cells internalized these vesicles. Once inside, the CCT2 cargo raised both CCT2 and c-Myc levels in the recipient cells, altered their cell-cycle regulators, accelerated their cell-cycle progression, and enhanced their resistance to cisplatin. Critically, vesicles derived from CCT2-depleted cells showed much weaker effects, confirming that the CCT2 payload itself was responsible for transmitting drug tolerance. This mechanism represents a form of non-genetic transfer of resistance, meaning that chemotherapy itself may inadvertently arm previously sensitive cells with the molecular machinery of survival, without any DNA mutation required.

Taken together, the findings reframe CCT2 from an obscure chaperonin subunit into a central node in the biology of head and neck squamous cell carcinoma. The protein promotes proliferation, migration, and invasion while simultaneously reducing cisplatin sensitivity through its interaction with and stabilization of c-Myc, and the apoptotic vesicle pathway adds a population-level mechanism by which resistance spreads through the tumor. For clinicians, the work suggests that CCT2 expression could serve as a biomarker for identifying patients whose tumors are likely to resist cisplatin, potentially guiding treatment intensification or alternative regimens. For drug developers, CCT2 presents an attractive therapeutic target, particularly because its effects appear to converge on a single, druggable axis involving c-Myc stabilization. As head and neck cancer continues to exact a devastating toll worldwide, strategies that disrupt the CCT2-c-Myc partnership, or that intercept the vesicle-mediated trafficking of resistance between tumor cells, could finally offer a way to blunt the rapid progression and treatment failure that have long characterized this aggressive malignancy.

Subject of Research: The role of the chaperonin subunit CCT2 in stabilizing c-Myc to drive progression and cisplatin chemoresistance in head and neck squamous cell carcinoma

Article Title: CCT2 drives HNSCC progression and cisplatin chemoresistance

Article References: CCT2 drives HNSCC progression and cisplatin chemoresistance. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: head and neck squamous cell carcinoma, CCT2, chaperonin-containing TCP-1 complex, c-Myc, cisplatin resistance, chemoresistance, epithelial-mesenchymal transition, apoptotic vesicles, cell cycle, CCND1, CCNE1, Genes & Diseases

Researchers at Heinrich-Heine-University Düsseldorf, led by Dennis Sohn and colleagues, report that pediatric medulloblastoma cells carrying functional, wild-type p53 do not simply die when bombarded with gamma irradiation. Instead, many of them enter senescence, a terminal and stable arrest of the cell cycle. These zombie-like cells stop dividing but refuse to die, lingering in the tissue for weeks. Crucially, the team showed that these irradiated, senescent tumor cells can then be selectively wiped out with senolytic drugs—compounds designed to eliminate senescent cells. The finding opens a potential two-step strategy: radiation first drives susceptible tumor cells into senescence, and senolytics then clear them away.

The study compared two SHH-activated medulloblastoma cell lines with fundamentally different genetic backgrounds. ONS76 cells carry wild-type p53, the master tumor suppressor that decides a cell’s fate after catastrophic DNA damage. UW228-3 cells carry a mutated, dysfunctional p53. When both lines were exposed to a 20 Gy dose of gamma irradiation, their responses diverged dramatically. UW228-3 cells detached from the culture dish and degraded completely within three to seven days. ONS76 cells, by contrast, remained attached for more than fifty days, flattening out and swelling enormously in both cell body and nucleus—classic hallmarks of senescence.

The molecular evidence followed the morphology. Irradiated ONS76 cells showed a dose-dependent stabilization of p53 and a strong increase in p21, the cyclin-dependent kinase inhibitor encoded by the CDKN1A gene that enforces the senescence arrest. They also accumulated senescence-associated beta-galactosidase activity, a lysosomal enzyme widely used as a senescence marker, and built up lipofuscin, the pigment-like cellular debris characteristic of aged or senescent cells. When the researchers knocked down p53 or p21 using siRNAs, the senescence program collapsed: far fewer cells became senescent and substantially more died instead. This established that radiation-induced senescence in these cells is strictly p53/p21-dependent.

The p53-mutated UW228-3 cells told the opposite story. They showed only a faint, transient rise in beta-galactosidase activity and never developed senescent morphology. Instead, measurements of lactate dehydrogenase release—a marker of plasma membrane destruction—and of DEVDase-like caspase activity revealed that they died by apoptosis, the controlled self-destruction pathway. A pan-caspase inhibitor, q-VD-OPh, completely abolished this cell death while leaving senescence untouched in the wild-type line. The team also employed a recently developed fluorescent lipofuscin binder, GLF16, alongside the amine-reactive viability dye Zombie-violet, allowing simultaneous flow cytometric quantification of senescent and dead cells with sharper discrimination than traditional staining.

The researchers then turned to c-Myc, a proto-oncogene that serves as a crucial negative prognostic factor in medulloblastoma and is known to antagonize p21. Using engineered ONS76 and UW228-3 lines that constitutively overexpress c-Myc, they found that the oncogene tipped the balance away from senescence. In irradiated ONS76/c-Myc cells, p21 protein levels dropped—though p21 mRNA levels did not, indicating that c-Myc interferes with p21 protein production or stability rather than its transcription. Fewer cells adopted senescent morphology, and more cells died, a death that q-VD-OPh could block even though it was not accompanied by elevated caspase activity. Notably, this c-Myc effect operated independently of p53 status. The senescent population in c-Myc-overexpressing cells also proved far more resistant to senolytic treatment, underscoring how oncogene dosage can shape therapeutic vulnerability.

The therapeutic payoff came in the final set of experiments. Seven days after irradiation, when the ONS76 cultures had become fully senescent, the researchers treated them with four senolytic compounds: the BCL-2 family inhibitors Navitoclax and Venetoclax, and the PI3K inhibitors PX-866 and BAY 80-6946 (Copanlisib), the latter already FDA-approved. All four killed the senescent cells in a dose-dependent manner. Navitoclax, however, also eliminated proliferating cells at the highest concentration tested, 30 µM—a reminder of the well-known toxicity problem that has complicated its clinical use, since healthy non-senescent cells are targeted at higher doses. The PI3K inhibitors, by contrast, showed a cleaner specificity for the senescent population.

The clinical logic behind this approach is compelling. Medulloblastoma is unusual among cancers in that relatively few tumors harbor p53 mutations, and in the SHH-activated subtype, p53 status actually defines two distinct risk groups: p53-mutated tumors carry a five-year overall survival of roughly 41 percent and are classified as high risk, while p53 wild-type tumors fare far better at about 81 percent. The new findings suggest that these two groups respond to radiotherapy in mechanistically different ways—senescence in the wild-type setting, apoptosis in the mutated one—a distinction invisible to standard proliferation-based cytotoxicity assays. Senolytic combination therapy would therefore primarily apply to the intermediate-risk, p53 wild-type group, where it could potentially improve outcomes further while reducing the radiation dose needed for tumor control.

The broader context strengthens the case. Senescent cells are not inert; they secrete a cocktail of cytokines and chemokines known as the senescence-associated secretory phenotype, or SASP, which drives chronic tissue microinflammation and can support tumor relapse. Craniospinal irradiation is associated with accelerated brain aging in survivors, and studies in glioblastoma have already shown that eliminating therapy-induced senescent cells with Navitoclax attenuates recurrence. Mouse studies of whole-brain irradiation likewise suggest that senolytic clearance protects cognitive function and the blood-brain barrier. Because senescence can be triggered at lower radiation doses than outright cell death, pairing senolytics with craniospinal irradiation might one day allow clinicians to cure tumors with less radiation exposure while simultaneously mopping up the senescent cells that radiation leaves behind.

Important caveats remain. The entire study was conducted in cell lines rather than animal models or patients, and the exact nature of the c-Myc-driven, caspase-inhibitable cell death observed in the overexpressing cells is still unclear. The authors themselves note that it would be intriguing to test whether JQ1, a bromodomain inhibitor that suppresses c-Myc signaling, could push c-Myc-high, p53 wild-type medulloblastoma cells back into a senescence-permissive state and thereby restore their susceptibility to senolytics. Still, the work is the first to document radiation-induced senescence in medulloblastoma cells and to demonstrate that these cells can be eliminated with existing senolytic drugs. If the strategy survives translation into preclinical models, it could reshape how one of pediatric oncology’s most grueling treatments is delivered—turning the very cells that radiation strands between life and death into targets for a second, cleaner strike.

Subject of Research: Radiation-induced cellular senescence in pediatric medulloblastoma and its targeting by senolytic drugs

Article Title: p53 wild-type/low c-Myc-expressing ONS76 pediatric medulloblastoma cells become senescent after gamma-irradiation and can be eliminated by senolytic substances

Article References: Sonntag, J., Preugschas, R.-L., Jazmati, D., Qin, N., Neuwahl, J., Matuschek, C., Remke, M., Budach, W., Hörner-Rieber, J., & Sohn, D. (2026). p53 wild-type/low c-Myc-expressing ONS76 pediatric medulloblastoma cells become senescent after gamma-irradiation and can be eliminated by senolytic substances. Cell Death Discovery, 12(1), Article 410. https://doi.org/10.1038/s41420-026-03404-4

Image Credits: AI Generated

DOI: 10.1038/s41420-026-03404-4

Keywords: medulloblastoma, senescence, senolytics, p53, c-Myc, p21, gamma irradiation, craniospinal irradiation, Navitoclax, PI3K inhibitors, SASP, pediatric brain tumor

To understand why this matters, it helps to start with PROTACs, or PROteolysis TArgeting Chimeras. These bifunctional molecules are the flagship technology of targeted protein degradation, one of the most exciting areas of modern drug discovery. A PROTAC has two business ends: one binds a protein that scientists want eliminated, and the other recruits an E3 ubiquitin ligase, the cellular machinery that tags unwanted proteins for destruction by the proteasome. By physically dragging the target protein into contact with the ligase, a PROTAC catalyzes the formation of a protein-protein interaction that would never happen naturally, triggering the cell’s own waste-disposal system to chew up the target. Unlike conventional inhibitors, which merely block a protein’s activity and must be present at high concentrations to keep it suppressed, degraders can eliminate the protein altogether and work catalytically, so a single molecule can destroy many copies of its target.

The problem is that this power comes with a loss of control. Because PROTACs act anywhere they reach in the body, they can degrade their target proteins in healthy tissues as well as diseased ones, producing side effects that are difficult to predict. The field has therefore been searching for ways to impose spatiotemporal control, meaning the ability to restrict drug activity to a specific place at a specific time. Light is the most attractive remote trigger for this purpose, since it can be focused on a tissue with exquisite precision and switched on and off at will. Photocaging strategies, in which a light-sensitive chemical group masks a drug’s activity until illumination releases it, have been applied to PROTACs before, but earlier systems suffered from weak contrast between the dark and illuminated states, or required high-energy ultraviolet light that damages cells and penetrates poorly into tissue.

The team behind the new work, led by Dmytro Havrylyuk, David K. Heidary and Edith C. Glazer at North Carolina State University, together with colleagues at the University of Kentucky, took a different approach by building the light switch out of a metal. Their RuPHOTACs use ruthenium(II) coordination complexes as photocages wrapped around the PROTAC scaffold. Ruthenium complexes have a distinctive photochemistry: when they absorb light, they can undergo ligand photodissociation, cleanly releasing the molecule attached to the metal. Crucially, the absorption properties of these complexes can be tuned so that the release is driven by low-energy red light rather than damaging ultraviolet wavelengths. Red light penetrates deeper into biological tissue and is far gentler on living cells, which is why the authors emphasize that their systems are optimized for biological applications rather than merely demonstrated in a cuvette.

To prove the concept, the researchers targeted bromodomain-containing proteins, a family of epigenetic regulators that read acetylation marks on histones and help control gene expression. These proteins, particularly members of the BET family, are major targets in cancer research because many tumors depend on them to drive the expression of growth-promoting genes. In the dark, the ruthenium cage keeps the RuPHOTAC inert; when illuminated with red light, the cage releases the active degrader, which then recruits the E3 ligase and drags the bromodomain protein to the proteasome. The team showed that the compounds strongly reduced not only the levels of the bromodomain targets themselves but also the abundance of two important downstream proteins, c-MYC and PIM1, both of which are transcriptional targets of BET proteins and both of which are heavily implicated in cancer progression. Knocking down c-MYC in particular is a longstanding goal in oncology, since the protein has been notoriously difficult to drug with conventional small molecules.

The quantitative performance of the new compounds is what sets the study apart. The authors report that the RuPHOTACs achieve the highest selectivity for activation in the light versus the dark reported for photocontrolled degraders, meaning that in the absence of light the molecules are essentially silent, while a brief illumination unleashes full degrading activity. They also show improved potency against the target proteins compared with prior systems, so less compound is needed to achieve the same degree of degradation. Most strikingly, the increased efficacy extends to animal work: using low-energy red light, the team demonstrated increased efficacy in vivo, a critical benchmark because many photochemical technologies that shine in cell culture fail when confronted with the optical and biological complexity of a living organism.

Measuring protein degradation sounds simple but is surprisingly tricky, and the study introduces an elegant solution to a chronic measurement problem. Traditional assays often rely on antibodies or fluorescent tags that report total protein abundance, but those signals conflate two opposing processes: the destruction of existing protein molecules and the continuous production of new ones. If a drug slows protein synthesis as a side effect, or if the cell ramps up production to compensate for degradation, the apparent degradation rate becomes distorted. To disentangle these effects, the researchers created fusion proteins in which the target of interest is fused to Dendra2, a photoconvertible fluorescent protein. Dendra2 can be switched from a green to a red fluorescent state by light, allowing the researchers to mark a defined cohort of pre-existing protein molecules and then watch that cohort disappear over time as the PROTAC does its work.

This bifunctional reporter system offers several advantages over previously described PROTAC reporters. Because the photoconverted molecules are already synthesized, any change in the red fluorescence signal reflects true degradation rather than changes in new protein production. At the same time, the green signal tracks newly synthesized protein, so the researchers can monitor both destruction and replenishment simultaneously in the same living cell. Importantly, the approach does not perturb translation, proteostasis, or cell health, meaning the measurements reflect normal cellular physiology rather than artifacts introduced by the measurement itself. The authors argue that this makes the system superior to prior reporter strategies for live-cell analysis of protein degradation, and it could become a standard tool for the broader targeted degradation community, which has long struggled with assay artifacts.

The study also carries a broader message about the role of metals in chemical biology. Ruthenium is not a component of any natural biomolecule, and metal complexes are often viewed with suspicion in drug development because of concerns about stability and toxicity. Yet the work demonstrates that incorporating a metal component within an organic PROTAC confers multiple concrete advantages: a clean and efficient photorelease mechanism, absorption profiles compatible with low-energy red light, and tunable photophysical properties that organic photocages struggle to match. The researchers suggest that this design philosophy, using coordination chemistry as an engineering platform for light-controlled drugs, could extend well beyond the specific bromodomain targets validated here, potentially allowing any PROTAC scaffold to be fitted with a ruthenium switch.

Caveats remain, as they always do at this stage of translation. The work was supported by the National Institutes of Health and the Kentucky Cabinet for Health and Family Services, and the authors declare no competing interests, but moving from validated compounds in cells and animal models toward clinical candidates will require extensive safety evaluation of the ruthenium payloads, optimization of light delivery to internal organs, and pharmacokinetic studies that the current paper does not address. The article itself was shared early as a peer-reviewed accepted manuscript subject to further editorial processing. Even so, the combination of near-total dark-state silence, red-light activation, in vivo efficacy, and a genuinely improved measurement technology makes RuPHOTACs one of the most complete demonstrations to date that protein degradation can be placed under remote optical control. For a field racing to make degraders safer and more precise, that is a result worth watching closely.

Subject of Research: Light-activated ruthenium photocaged PROTACs for spatiotemporally controlled targeted protein degradation

Article Title: RuPHOTACs provide photocontrol over protein degradation with optimized properties for biological applications

Article References: Havrylyuk, D., LaMore, A. P., Al-Hamaly, M. A., Blackburn, J. S., Heidary, D. K., & Glazer, E. C. (2026). RuPHOTACs provide photocontrol over protein degradation with optimized properties for biological applications. Nature Communications. https://doi.org/10.1038/s41467-026-78110-x

Image Credits: AI Generated

DOI: 10.1038/s41467-026-78110-x

Keywords: targeted protein degradation, PROTACs, RuPHOTACs, ruthenium photocages, photochemistry, E3 ubiquitin ligase, bromodomain proteins, c-MYC, Dendra2 reporter, red light activation, chemical biology, cancer research

The research began with a straightforward clinical observation. When the team, led by corresponding authors Yu Qian and Yao Lu, examined tumor samples from osteosarcoma patients, they found that tumors with high levels of HTR1D expression were markedly more likely to have metastasized and to have responded poorly to doxorubicin-based chemotherapy. That correlation alone would not have been remarkable, since many proteins correlate with aggressive disease without actually causing it. What elevates this finding is the depth of the mechanistic work that followed. Using laboratory-grown osteosarcoma cells, the researchers showed that silencing HTR1D dramatically suppressed the cells’ ability to migrate and invade, the two cellular behaviors that underpin metastasis. More strikingly, when they implanted tumors into animal models, knocking down HTR1D reversed resistance to doxorubicin and curtailed the spread of the disease in living tissue.

To understand how a serotonin receptor exerts such power inside a bone tumor, the investigators turned to the tools of structural and molecular biology. Through co-immunoprecipitation, GST pull-down experiments, and precise point-mutation analysis, they demonstrated that HTR1D physically binds to a protein called GNAI1, an intracellular signaling partner. This interaction is not incidental: it activates the MAPK signaling pathway, a canonical growth-promoting cascade that cancer cells routinely hijack. The team also identified a specific tyrosine residue at position 137 of the HTR1D protein as critical; when they mutated this amino acid, the receptor lost much of its ability to drive metastatic behavior in the cells. This level of detail matters because it converts a correlation into a targetable mechanism, giving drug developers a defined molecular interface to attack.

Perhaps the most conceptually surprising discovery is that the pathway runs in a loop. The researchers found that c-MYC, one of the most notorious oncogenic transcription factors in all of cancer biology, sits upstream of HTR1D, binding to its gene and cranking up its production. But activated MAPK signaling, the very cascade that HTR1D triggers through GNAI1, in turn elevates c-MYC, which the team confirmed using luciferase reporter assays and immunofluorescence combined with fluorescence in situ hybridization on patient tissue sections. The result is a self-reinforcing positive feedback circuit: c-MYC makes more HTR1D, HTR1D activates MAPK through GNAI1, and MAPK makes more c-MYC. In effect, the tumor cell installs an accelerator that presses itself, explaining why osteosarcomas with high HTR1D behave so aggressively and why the phenotype is so difficult to dislodge with conventional chemotherapy alone.

The story does not end inside the tumor cell. Cancer is never a solo performance; it recruits the surrounding tissue, including immune cells, to serve its purposes. The researchers showed that HTR1D drives osteosarcoma cells to secrete CCL2, a chemokine that acts as a beacon for macrophages. When these immune cells arrive, CCL2 nudges them to polarize into the so-called M2 state, an immunosuppressive, tumor-promoting identity that helps cancers evade attack and remodel tissue to favor invasion. The team verified this through cell co-culture experiments in which depleting CCL2 impaired the polarization of tumor-associated macrophages, and through flow cytometry that characterized the M2 population. In animal models, depleting CCL2 inhibited metastasis and improved the sensitivity of tumors to doxorubicin, confirming that this immune axis is not a bystander but an active participant in treatment failure.

Then comes the twist that gives the circuit its name. The M2-polarized macrophages, once converted to the tumor’s side, produce serotonin, the 5-HT that HTR1D is built to detect. This serotonin flows back to the tumor cells and sustains the chemoresistant state, closing a second loop that spans two different cell types. The researchers noted that osteosarcoma cell lines themselves show serotonin synthesis potential according to data from the Human Protein Atlas, suggesting the tumor microenvironment is saturated with the ligand this receptor craves. In other words, the cancer engineers its own supply chain: it summons macrophages with CCL2, converts them into serotonin factories, and then uses the serotonin to keep its own pro-survival signaling humming. It is a textbook example of the increasingly appreciated principle that tumors do not merely tolerate their microenvironment; they actively reprogram it into a supporting organ.

Against this elaborate biological backdrop, the therapeutic finding is what makes the paper travel beyond the specialty literature. Rather than trying to block serotonin itself, which would cause widespread neurological and cardiovascular side effects, the team searched for a small molecule that could competitively disrupt the physical handshake between HTR1D and GNAI1. Using computer-simulated screening of compound libraries, they identified poliumoside, a natural glycoside compound, as a candidate blocker. Subsequent experiments confirmed that poliumoside suppresses the HTR1D-GNAI1-MAPK signaling axis in osteosarcoma cells, dampens their metastatic behavior in vitro, and reduces proliferation markers such as Ki67 in xenograft tumors in vivo. Because the compound targets the protein-protein interaction rather than the receptor’s serotonin-binding site, it offers a degree of specificity that direct receptor antagonists would struggle to achieve.

The dual nature of the target is what excites many observers of translational oncology. Drugs that address only metastasis leave chemoresistance intact, and drugs that resensitize tumors to chemotherapy do nothing to stop cells from already spreading. A single intervention that collapses both phenotypes, by severing the feedback loop that drives them in parallel, could in principle change the trajectory of the disease at its root. The authors suggest that poliumoside, or derivatives built upon its scaffold, could be developed as a dual-action therapeutic candidate to be used alongside doxorubicin, restoring the potency of the standard regimen while simultaneously choking off the metastatic program. For a cancer in which five-year survival for metastatic cases remains dismal despite decades of multimodal treatment, any strategy that attacks two vulnerabilities at once is worth serious attention.

Caveats remain, as they always do at this stage of translation. The work rests on cell lines, patient tissue correlations, and xenograft models, which are powerful but imperfect proxies for human disease; poliumoside’s pharmacokinetics, toxicity profile, and efficacy in humans have not yet been established, and the study was funded by regional research grants including the Scientific Research Project of Suqian Health Commission and the Development Fund of The Affiliated Hospital of Xuzhou Medical University. Still, the paper delivers something rare: a complete mechanistic arc from a clinically observed biomarker, through a defined intracellular feedback circuit and an intercellular immune axis, to a druggable interface and a candidate compound already in hand. It also adds HTR1D to a growing list of neural signaling molecules that cancers co-opt, reinforcing the idea that the boundary between neurobiology and oncology is far blurrier than textbooks once suggested. If follow-up studies validate the approach, the humble serotonin receptor may become one of the most consequential targets in bone cancer therapy.

Subject of Research: The role of the serotonin receptor HTR1D in osteosarcoma metastasis and doxorubicin resistance

Article Title: HTR1D triggers osteosarcoma metastasis and doxorubicin resistance via c-MYC/MAPK feedback and CCL2/5-HT-mediated M2 polarization

Article References: Shi, C., Li, J., Wang, Y., Zeng, X., Wang, Y., Liu, G., Huang, P., Xu, Q., Wang, M., Qian, Y., & Lu, Y. (2026). HTR1D triggers osteosarcoma metastasis and doxorubicin resistance via c-MYC/MAPK feedback and CCL2/5-HT-mediated M2 polarization. Journal of Translational Medicine. https://doi.org/10.1186/s12967-026-09048-3

Image Credits: AI Generated

DOI: 10.1186/s12967-026-09048-3

Keywords: osteosarcoma, HTR1D, doxorubicin resistance, metastasis, MAPK pathway, c-MYC, GNAI1, CCL2, serotonin, M2 macrophage polarization, poliumoside, tumor microenvironment

The research team focused on canavanine, a naturally occurring structural analogue of L-arginine found in certain legumes such as jack bean. Because canavanine closely resembles arginine in shape and charge, cells can mistakenly incorporate it into proteins in place of arginine, a process that produces malformed, dysfunctional proteins and ultimately cytotoxicity. This property has long made canavanine an object of interest in cancer research, but its precise effects on the regulatory circuitry of arginine metabolism had remained incompletely understood. The new work demonstrates that canavanine does far more than simply poison protein synthesis; it actively participates in the cellular signaling networks that govern how tumor cells sense and respond to arginine availability.

Central to the study is argininosuccinate synthetase 1, or ASS1, an enzyme of the urea cycle that catalyzes the rate-limiting step in the conversion of citrulline and aspartate into argininosuccinate, a precursor of arginine. ASS1 expression is a key determinant of whether a cancer cell can survive arginine deprivation therapy. Tumors with low or silenced ASS1 cannot make their own arginine and are therefore vulnerable to enzymes such as recombinant human arginase 1 or arginine deiminase, which deplete circulating arginine. Conversely, tumors that retain robust ASS1 expression can adapt to arginine starvation by synthesizing the amino acid from citrulline, rendering deprivation therapy ineffective. Understanding what controls ASS1 expression under conditions of arginine stress is therefore of substantial clinical relevance.

Using colorectal carcinoma cell lines cultivated in both complete medium and arginine-free medium, the investigators systematically examined how canavanine affects cellular signaling and gene regulation. Their most striking finding was that canavanine represses transcription of the ASS1 gene in colorectal carcinoma cells subjected to arginine starvation. In other words, the plant mimic does not merely stand in for arginine in protein synthesis; it also mimics arginine’s role in the regulatory pathways that shut down arginine biosynthesis when the cell senses sufficient arginine supply. This feedback-like behavior, now triggered by a drug-like compound, could deepen the metabolic deficit that arginine deprivation therapy is designed to create.

Intriguingly, the researchers established that this repression of ASS1 occurs in a c-Myc-independent manner. The transcription factor c-Myc has been implicated in the regulation of metabolic genes, including components of the urea cycle, in several cancer contexts, and one might have expected its involvement here. The finding that canavanine-mediated ASS1 silencing proceeds without c-Myc suggests that alternative regulatory mechanisms, possibly involving other transcriptional repressors or epigenetic modifications, are at play. This distinction matters because it points to previously unappreciated control points in the arginine metabolic network that could be targeted pharmacologically to sensitize tumors to deprivation therapy.

Beyond gene regulation, the study documented that canavanine dysregulates broader cellular signaling pathways in the stressed colorectal carcinoma cells. The authors observed effects consistent with the compound mimicking arginine in several regulatory routes, echoing behaviors previously described for other arginine analogues such as indospicine, thioarginine, and homoarginine, which the team considered in framing their experimental design. Analogues of amino acids have historically served as powerful probes of cellular metabolism precisely because they infiltrate the same transport, biosynthetic, and regulatory systems as their natural counterparts. By mapping which signaling nodes respond to canavanine under arginine starvation, the study provides a molecular picture of how tumor cell physiology unravels when arginine homeostasis is doubly compromised, first by external deprivation and then by internal mimicry.

Perhaps the most therapeutically consequential observation is that pre-exposure to arginine deprivation additionally sensitizes colorectal carcinoma cells to the cytotoxic effects of canavanine. Cells that were first grown in arginine-free conditions became more vulnerable to subsequent canavanine treatment than cells maintained in complete medium. This sequencing effect suggests that arginine starvation primes tumor cells, weakening their metabolic flexibility and protein synthesis machinery, so that the counterfeit amino acid inflicts maximal damage once it is introduced. Clinically, this raises the possibility of rational combination and sequential regimens in which an arginine-degrading enzyme is administered first, followed by canavanine, to achieve a two-step metabolic assault that tumor cells cannot easily withstand.

The findings may help resolve two persistent shortcomings of arginine deprivation therapy. The first is resistance: tumors that maintain ASS1 expression can escape starvation by producing arginine from citrulline, and some tumors upregulate ASS1 adaptively under treatment pressure. A compound that actively represses ASS1 transcription, as canavanine does under arginine-free conditions, could counteract this adaptive route and keep the metabolic door closed. The second shortcoming is incomplete efficacy as a monotherapy, which has motivated the search for combinations. The demonstration that deprivation pre-exposure potentiates canavanine cytotoxicity offers an evidence-based rationale for scheduling these agents together, a strategy that could extend to cancers beyond colorectal carcinoma, including entities such as melanoma and hepatocellular carcinoma that have been evaluated for arginine dependency.

The work also carries broader scientific significance for the field of cancer metabolism. It illustrates that a single metabolite analogue can simultaneously act at multiple levels, substituting for arginine during translation, perturbing signal transduction, and reshaping the transcriptional landscape of metabolic genes. This pleiotropy underscores the dense interconnection between nutrient sensing, protein homeostasis, and gene expression in tumor cells. Moreover, because ASS1 silencing in many tumors occurs through epigenetic mechanisms such as promoter methylation, the observation that canavanine can drive ASS1 downregulation in a c-Myc-independent way invites further investigation into whether amino acid availability itself, and arginine mimics in particular, can shape the epigenetic state of metabolic genes during therapy.

The study, conducted by G. Y. Shuvayeva, Y. P. Bobak, O. I. Chen, O. I. Vovk, and O. V. Stasyk, is available as an open access article, allowing clinicians, cancer biologists, and metabolic researchers worldwide to examine the data in full. While the experiments were performed in vitro and will require validation in preclinical models before any translational application, they provide a compelling mechanistic foundation for combining arginine deprivation with canavanine in metabolic therapeutic modalities for colorectal carcinoma and potentially other ASS1-deficient cancers. As arginine deprivation therapy continues to be evaluated across a number of tumor entities, this work adds a molecularly grounded rationale for the next generation of combination strategies aimed at starving tumors of the amino acids they can no longer live without.

Subject of Research: Effects of canavanine on cellular signaling and ASS1 expression in colorectal carcinoma cells under arginine deprivation

Article Title: Canavanine dysregulates cellular signaling and represses ASS1 under arginine deprivation in colorectal carcinoma cells

Article References: Shuvayeva, G. Y., Bobak, Y. P., Chen, O. I., Vovk, O. I., & Stasyk, O. V. (2026). Canavanine dysregulates cellular signaling and represses ASS1 under arginine deprivation in colorectal carcinoma cells. Cancer Cell International. https://doi.org/10.1186/s12935-026-04450-9

Image Credits: AI Generated

DOI: 10.1186/s12935-026-04450-9

Keywords: arginine deprivation therapy, canavanine, ASS1, colorectal carcinoma, cancer metabolism, argininosuccinate synthetase, urea cycle, c-Myc, chemotherapy, amino acid analogue, cancer therapy, metabolic treatment

The investigation began with an unbiased metabolomic survey of mice with chemically induced colitis. Rather than confirming the team’s expectations, the data pointed somewhere unexpected: levels of pantothenate, the vitamin B5-derived precursor of coenzyme A, were markedly elevated in both the colon and serum of colitic animals. Because pantothenate must be phosphorylated by pantothenate kinases, known as PANK enzymes, before it can enter the coenzyme A biosynthetic pathway, its accumulation signaled that the pathway itself was stalled. Of the three PANK isoforms present in the colon, one stood out. PANK3, the dominant intestinal form, was dramatically reduced at both the messenger RNA and protein levels in colitic mice, and the drop was confirmed by immunohistochemical staining of the colonic epithelium.

The downregulation was not merely a rodent curiosity. Analyzing gene expression datasets from human intestinal biopsies, the researchers found PANK3 significantly decreased in patients with active Crohn’s disease and active ulcerative colitis compared with inactive disease and healthy controls. Tissue staining of patient biopsies from Jiangsu Province Hospital corroborated the finding, showing diminished PANK3 specifically within the intestinal epithelium. When human colon epithelial cell lines were exposed to the inflammatory cytokines TNF-alpha and IFN-gamma, PANK3 levels fell again, replicating in a dish what had been observed in diseased tissue. Taken together, the evidence positioned epithelial PANK3 deficiency as a consistent pathological feature of inflammatory bowel disease across species.

To determine whether the loss of PANK3 actually drives barrier failure rather than simply accompanying it, the team deployed a combination of pharmacological and genetic tools. In cultured epithelial cells subjected to inflammatory challenge, a small-molecule PANK3 agonist called PZ-2891 boosted the expression of intercellular junctional proteins, while Hopantenate, a competitive PANK inhibitor, worsened their decline. In Caco-2 monolayer models, transepithelial electrical resistance and paracellular permeability assays showed that activating PANK3 restored barrier function while blocking it deepened the damage. Directly overexpressing PANK3 in HT29 and NCM460 cells rescued inflammation-induced barrier injury, whereas silencing the gene produced the opposite effect, confirming the relationship in both directions.

In living animals the results were even more striking. Mice engineered to overexpress PANK3 specifically in the intestine via adeno-associated virus were markedly protected against DSS-induced colitis, exhibiting less weight loss, shorter reduction in colon length, preserved crypt architecture, maintained goblet cell populations and reduced inflammatory infiltration. Serum FITC-dextran assays demonstrated tighter barrier integrity, and transmission electron microscopy revealed that shortened microvilli and disrupted apical junction complexes were structurally repaired in the PANK3-overexpressing animals. Conversely, intestinal PANK3 knockdown exacerbated every measure of disease severity and barrier breakdown, establishing PANK3 as a necessary guardian of the epithelial lining during colonic inflammation.

The mechanism connecting a metabolic enzyme to such profound structural changes emerged from transcriptomic profiling. PANK3 overexpression suppressed gene clusters encoding proinflammatory cytokines, extracellular matrix components and drivers of epithelial-to-mesenchymal transition, or EMT, a developmental program in which epithelial cells lose their junctions and polarity and take on migratory, mesenchymal characteristics. In chronic inflammation, pathological persistence of EMT dismantles tight junctions and adherens junctions, degrades the basement membrane and promotes fibrotic remodeling, a signature observed in clinical IBD mucosal samples and correlated with disease severity and therapeutic resistance. PANK3, the study found, acts as a powerful brake on this process, downregulating mesenchymal markers such as vimentin and N-cadherin, suppressing the EMT-driving transcription factors Snail and Twist, and preserving junctional proteins including ZO-1, E-cadherin, occludin and claudins.

Gene set enrichment analysis revealed that the EMT-suppressing effects of PANK3 operated through inhibition of the PI3K/AKT and MAPK signaling pathways, both well-established inducers of the transition. Phosphorylation of PI3K, AKT and ERK fell sharply in PANK3-overexpressing mice and rose in knockdown animals, indicating the enzyme’s influence extended deep into canonical signal transduction. The critical mediator proved to be coenzyme A itself. Quantitative LC-MS/MS measurements showed that PANK3 overexpression significantly increased colonic free CoA abundance while knockdown depleted it, and supplying exogenous CoA to cultured epithelial cells was sufficient to suppress inflammation-induced EMT and downstream signaling. When pantothenate was completely removed from the culture medium, the barrier protection conferred by PANK3 agonism or overexpression was largely abolished, confirming that the enzyme’s benefit depends on the raw material for CoA synthesis.

Having established what PANK3 does, the team turned to why it disappears during colitis. Screening transcription factor prediction databases against the Pank3 promoter uncovered c-Myc, the notorious proto-oncogene, as the prime candidate. c-Myc was significantly upregulated in the colonic lesions of ulcerative colitis patients and in multiple experimental colitis models, and chromatin immunoprecipitation confirmed that c-Myc binds directly to three sites in the Pank3 promoter region. A dual-luciferase reporter assay demonstrated that c-Myc overexpression dramatically represses Pank3 promoter activity, and pharmacological inhibition of c-Myc with the inhibitor 10058-F4 restored PANK3 expression in a dose-dependent manner in cells. In mice, c-Myc inhibition ameliorated DSS-induced colitis, rescued PANK3 levels and improved barrier integrity, establishing a clear c-Myc-PANK3-EMT axis in which inflammation-driven c-Myc overexpression silences PANK3, depletes coenzyme A, permits EMT and dismantles the epithelial barrier.

Perhaps the most clinically tantalizing finding came from a high-throughput virtual screen for PANK3 agonists, which identified folic acid, a widely available and inexpensive B vitamin, as the top candidate. Molecular docking predicted binding to key residues including Lys24, Ser192, Arg207, Val268, Asn299 and Trp341, and a cellular thermal shift assay confirmed that folic acid directly stabilizes the PANK3 protein. Oral folic acid at 30 milligrams per kilogram significantly ameliorated DSS-induced colitis in mice, restoring body weight, colon length, crypt architecture and goblet cell populations while elevating colonic coenzyme A levels. Electron microscopy showed repaired microvilli and restored apical junction complexes, junctional proteins were upregulated, EMT markers and matrix metalloproteinases declined, and PI3K/AKT and MAPK activation was suppressed. Crucially, the protection vanished when PANK3 was knocked down, demonstrating that folic acid’s benefit is PANK3-dependent.

The findings carry substantial implications beyond the immediate identification of a druggable target. A meta-analysis cited in the study indicates that higher folate levels are associated with reduced risk of inflammatory bowel disease, lending clinical plausibility to the mechanistic work, although the therapeutic doses used in mice exceed typical supplementation levels and would likely require colon-targeted formulations such as enteric-coated tablets to maximize local exposure while limiting systemic dose. The authors also suggest that circulating pantothenate and coenzyme A levels, together with intestinal PANK3 expression, could serve as accessible biomarkers for diagnosis and treatment monitoring, pending validation in larger multi-center cohorts. Because reduced PANK3 has previously been identified as a diagnostic marker for early-stage colorectal cancer, and c-Myc is a well-established oncogene, the axis also offers a plausible mechanistic thread connecting chronic colitis to malignant transformation. Open questions remain, including precisely how PANK3-derived coenzyme A suppresses the PI3K/AKT and MAPK pathways, whether coenzyme A acts through post-translational modifications such as protein CoAlation, and whether PANK3 possesses non-catalytic functions. Even so, the study reframes ulcerative colitis in part as a metabolic disease of the epithelial barrier and positions PANK3 agonism, potentially through a humble vitamin, as a promising avenue for restoring the gut’s broken wall.

Subject of Research: Metabolic regulation of intestinal epithelial barrier integrity by the c-Myc-PANK3-coenzyme A axis in ulcerative colitis.

Article Title: c-Myc-PANK3-EMT axis regulates the structure and function of intestinal barrier in ulcerative colitis

Article References: Zhang, S., Chen, Y., Aa, N., Xu, C., Xie, T., Wang, Y., Cheng, T., Wang, M., Yu, H., Ji, X., Zhao, S., Wang, Y., Xiao, J., Xie, Y., Wang, G., & Aa, J. (2026). c-Myc-PANK3-EMT axis regulates the structure and function of intestinal barrier in ulcerative colitis. Journal of Advanced Research, 87, 931-946. https://doi.org/10.1016/j.jare.2025.12.007

Image Credits: AI Generated

DOI: 10.1016/j.jare.2025.12.007

Keywords: ulcerative colitis, PANK3, c-Myc, coenzyme A, epithelial-mesenchymal transition, intestinal barrier, folic acid, pantothenate kinase, inflammatory bowel disease, PI3K/AKT pathway, MAPK pathway, tight junctions