The research team, led by Zhao Lin and Ubaldo Martinez-Outschoorn, with contributions from Megan Bennett, Patrick Tassone, and Joseph M. Curry, mined The Cancer Genome Atlas databases for head and neck squamous cell carcinoma (HNSCC) and breast cancer (BRCA). They stratified tumors into four microenvironment subtypes based on immune and stromal characteristics: immune-enriched non-fibrotic, immune-enriched fibrotic, fibrotic, and immune-depleted. The fibrotic subtype—characterized by epithelial-mesenchymal transition (EMT), fibrosis, angiogenesis, and immune exclusion—showed the poorest overall survival in both cancer types. Critically, miR-145 expression was highest in these fibrotic tumors, suggesting that this microRNA could serve as a molecular fingerprint of the most aggressive microenvironmental state.

Gene Set Variation Analysis revealed that high miR-145 tumors were positively correlated with EMT, angiogenesis, NOTCH, hypoxia, TGF-β, Hedgehog, myogenesis, and Wnt/β-catenin signaling, while showing negative correlations with oxidative phosphorylation and interferon-γ pathways. Gene Set Enrichment Analysis across the top and bottom 25% of miR-145 expression identified 12 Hallmark, 37 Reactome, and 322 Gene Ontology pathways significantly enriched in miR-145-high tumors across both cancer types. Reactome analysis highlighted extensive extracellular matrix remodeling, including ECM organization, proteoglycan and collagen formation, integrin and laminin interactions, and matrix metalloproteinase activation. Gene Ontology analysis further revealed enrichment of angiogenic and lymphangiogenic programs, including sprouting angiogenesis, vasculogenesis, endothelial cell migration, and VEGF and PDGFR signaling.

Deconvolution of tumor microenvironment cell types using xCell analyses showed that high miR-145 expression was associated with increased endothelial cells and decreased immune cell infiltration in both HNSCC and BRCA. Innate immune populations, including mast cells and plasmacytoid dendritic cells, were reduced, with more pronounced depletion of adaptive immune cells, particularly B and T lymphocytes. Single-sample GSEA of the TCGA HNSCC dataset confirmed that tumors with high miR-145 displayed a highly fibrotic, immune-excluded phenotype, enriched for angiogenesis, cancer-associated fibroblasts, and extracellular matrix remodeling. Malignant cells in these tumors exhibited enhanced EMT and immune-evasive features, including increased myeloid-derived suppressor cell recruitment, reduced antigen processing and presentation, and diminished infiltration of M1 macrophages, Th1 cells, NK cells, and CD8-positive cytotoxic T cells.

EcoTyper deconvolution further refined the picture. MiR-145-high tumors were enriched for Carcinoma Ecotype 1 (CE1), which is associated with poor prognosis, low lymphocyte infiltration, and abundant periostin-positive fibroblasts, and depleted for CE9 and CE10 ecotypes, which are linked to improved survival and enhanced immune activity. Consistent with CE1, miR-145-high tumors were enriched for periostin-positive fibroblasts, partial EMT-like epithelial cells, and ANGPTL2-positive/NID2-positive tip-like endothelial cells, all associated with tumor progression and neovascularization. In contrast, cytotoxic GZMB-positive and GZMK-positive CD8 T cells, PRF1-positive NK cells, and CE9/CE10-associated T cells were reduced. Macrophage polarization also shifted toward an unfavorable phenotype, with decreased M1 macrophages and increased M2 macrophages.

To investigate the mechanism of miR-145 expression, the team established a coculture system of fibroblasts and carcinoma cells at a 4:1 ratio. After four days, exosomes were isolated from conditioned media and analyzed by miRNA array. miR-145 was highly enriched in fibroblast-derived exosomes compared with those from breast carcinoma cells under homotypic culture. Intracellular miR-145 expression was markedly higher in fibroblasts than in breast or head and neck carcinoma cells. Two coculture systems were then compared: a transwell setup with physical separation and a direct-contact coculture followed by GFP/RFP-based cell sorting. Only direct cell-cell juxtacrine interaction markedly induced miR-145 expression in carcinoma cells, pointing to membrane-bound NOTCH signaling as the likely mediator.

Proteomic analysis of Detroit562 cells ectopically expressing precursor miR-145 identified 21 proteins showing greater than 1.5-fold differential expression as candidate miR-145-regulated targets. Among them, phosphoserine phosphatase (PSPH) was the most upregulated protein, a key enzyme in the serine biosynthesis pathway metabolically linked to glycolysis. Protein-protein interaction network analysis revealed that glyceraldehyde-3-phosphate dehydrogenase (GAPDH) occupied the most connected node within the network, with cell death, proliferation, ATP production, and oxidative stress as the principal associated biological processes. Elevated GAPDH expression was associated with reduced overall survival in the TCGA HNSCC cohort (p = 0.01) and linked to a non-inflamed tumor microenvironment including fibrotic and immune-depleted subtypes. Conversely, miR-145 overexpression downregulated two autophagy-related proteins, CAPZB and SQSTM1, and increased LysoTracker and LysoSensor signals across multiple cancer cell lines, consistent with enhanced autophagy.

Mitochondrial activity assays using MitoTracker Orange showed that miR-145 increased mitochondrial mass and membrane hyperpolarization in MCF7, MDA231, FaDu, and Detroit562 cells. ATP production and glucose uptake were also elevated following miR-145 overexpression. Seahorse XF Cell Mito Stress Tests in MOC1 and Detroit562 cells revealed that miR-145 overexpression increased both oxygen consumption rate (OCR) and extracellular acidification rate (ECAR), indicating enhanced mitochondrial oxidative phosphorylation and glycolysis. In vivo, miR-145-overexpressing MOC1 cells coinjected with mouse embryonic fibroblasts formed larger tumors than controls, promoted tumor angiogenesis and lymphangiogenesis, increased expression of VEGFR2 and Jagged1, reduced CD8A-positive cytotoxic T-cell infiltration, and significantly increased fibrosis. Detroit562 cells overexpressing miR-145 co-injected with hTERT-BJ1 fibroblasts similarly promoted tumor growth with suppressed SQSTM1 and induced TOMM20 expression, consistent with elevated mitochondrial activity.

The requirement for carcinoma-fibroblast juxtacrine interaction to induce miR-145 suggested involvement of membrane-bound NOTCH signaling. Coculture markedly increased NOTCH1 expression in carcinoma cells, as shown by immunofluorescence and flow cytometry. Western blot showed that miR-145 overexpression induced the functional, cleaved intracellular domain of the Notch1 receptor (NICD). In the TCGA-HNSC dataset, the fibrotic subtype exhibited the highest expression of both miR-145 and the NOTCH signaling pathway, as well as the highest expression of the cell-surface Notch ligand JAG1, which initiates NOTCH signaling in neighboring cells. NOTCH1ΔNT overexpression significantly elevated miR-145 levels across multiple cell lines compared with controls, demonstrating a positive feedback loop between NOTCH signaling and miR-145.

Epigenetic changes, particularly DNA methylation, occur early in tumor development and can regulate gene expression. Bioinformatics and methylation-specific PCR analyses showed that miR-145 promoter methylation was markedly reduced in cocultured cancer cells compared with homotypic cultures, while fibroblasts exhibited lower methylation levels than carcinoma cells. Treatment with the DNA methylation inhibitor azacitidine (5-Aza) significantly increased miR-145 expression in cancer cells. Western blot showed increased TP53 and reduced DNMT1 and COMMD1 expression in hTERT-BJ1 and MCF7 cells. p53 can promote miR-145 post-transcriptional maturation, while DNMT1 encodes the primary enzyme responsible for maintaining DNA methylation patterns during cell division, and COMMD1 is a negative regulator of NFκB-HIF signaling. These findings indicate that miR-145 upregulation in tumors is driven by both NOTCH signaling and promoter DNA hypomethylation. The authors acknowledge that functional validation using miR-145 knockdown or knockout models would provide additional mechanistic insights, but note that miR-145 expression is markedly downregulated in tumor tissues compared with normal controls, so they focused on characterizing its baseline expression and functional associations across microenvironment subtypes. This study identifies miR-145 as a potential biomarker of the fibrotic tumor microenvironment, providing a foundation for future mechanistic studies and therapeutic strategies.

Subject of Research: Cancer Cell Biology

Article Title: MiR-145 reprogramming facilitates fibrotic trajectory in the tumor microenvironment

Article References: Lin, Z., Bennett, M., Tassone, P., Curry, J. M., & Martinez-Outschoorn, U. (2026). MiR-145 reprogramming facilitates fibrotic trajectory in the tumor microenvironment. Frontiers in Cell and Developmental Biology, 14, Article 1850756. https://doi.org/10.3389/fcell.2026.1850756

Image Credits: AI Generated

DOI: 10.3389/fcell.2026.1850756

Keywords: miR-145, tumor microenvironment, fibrosis, NOTCH signaling, immune evasion, EMT, cancer-associated fibroblasts, GAPDH, mitochondrial metabolism, hypomethylation, reprogramming, facilitates

The research team, led by Erwin Danil Yulian, Teguh Herdadi, and Karl Heinz Leonhardt Rowika, examined archived tumor tissue from 29 female TNBC patients treated between 2017 and 2022. All patients had histologically confirmed triple-negative disease, defined as estrogen receptor expression of 1 percent or less, progesterone receptor expression of 1 percent or less, and HER2 scores of 0 to 1+ or 2+ with negative in situ hybridization. Using immunohistochemistry on formalin-fixed paraffin-embedded blocks, the investigators scored vimentin expression semiquantitatively, from 0 for no staining to 3+ for strong cytoplasmic staining in more than 10 percent of tumor cells. Crucially, only cytoplasmic staining within invasive tumor epithelial cells was counted; staining in stromal fibroblasts, endothelial cells, and inflammatory cells was excluded, since vimentin is constitutively expressed in normal mesenchymal cells and would otherwise confound the analysis.

The results were striking. Vimentin expression was detected in 22 of 29 cases, or 75.9 percent of the cohort. Among these positive cases, 14 showed strong 3+ expression, 6 showed moderate 2+ expression, and only 2 showed weak 1+ expression. When the researchers correlated expression status with overall survival, defined as the time from diagnosis to death from any cause or last follow-up, the association was statistically significant at p = 0.019. Of the 22 patients with positive vimentin expression, 19 experienced mortality events, while only 3 remained alive at the end of the observation period. In contrast, among the 7 patients with negative vimentin expression, only 3 experienced mortality events and 4 were alive at final follow-up.

Kaplan-Meier survival curves told the same story visually. Patients with positive vimentin expression had a mean survival time of 20.86 plus or minus 2.01 months, with a 95 percent confidence interval of 16.90 to 24.82 months. Those with negative expression survived a mean of 30.42 plus or minus 4.36 months, with a 95 percent confidence interval of 21.87 to 38.98 months. The log-rank test confirmed a significant difference between the two curves at p = 0.004, indicating that vimentin expression status meaningfully affects patient prognosis in this population.

What makes vimentin such a potent prognostic signal? The protein is a mesenchymal intermediate filament that sits at the heart of the epithelial-mesenchymal transition, a developmental program hijacked by cancer cells that enhances motility, invasiveness, and metastatic potential. EMT activation is regulated by transcription factors such as Snail, Twist, and Slug, and by signaling pathways including TGF-beta/SMAD, STAT3, and Wnt/beta-catenin. Overexpression of vimentin reflects EMT activation, cytoskeletal remodeling, and increased therapeutic resistance. Previous studies support the Indonesian findings: Xu and colleagues reported that vimentin overexpression in TNBC enhances invasion and anthracycline resistance, while Fedele and colleagues found that high vimentin levels doubled mortality risk and were associated with distant metastasis, particularly to the lung and brain.

Beyond survival, the study explored whether vimentin correlated with conventional clinicopathological characteristics. No significant associations were observed with age, body mass index, tumor size, lymph node status, histopathological grade, or clinical stage, all p values exceeding 0.05. However, vimentin expression showed a significant correlation with Ki-67 expression at p = 0.045, suggesting a link between EMT activation and proliferative activity. This association implies that proliferation and EMT may occur in parallel, as both are regulated by TGF-beta and beta-catenin signaling, which induce vimentin, CCND1, and MYC transcription. Inflammatory cytokines such as IL-6 and TNF-alpha further enhance this process via the JAK/STAT pathway, supporting tumor cell survival under oxidative and hypoxic stress.

In Cox regression analysis, vimentin expression emerged as an independent predictor of overall survival with a hazard ratio of 5.64 and a 95 percent confidence interval of 1.39 to 22.7 at p = 0.015. Adequate therapy was also significantly associated with survival, with a hazard ratio of 4.05 and a 95 percent confidence interval of 1.37 to 11.9 at p = 0.011. In contrast, conventional variables including tumor size, lymph node status, histopathological grade, and Ki-67 expression showed no statistically significant association with survival outcomes. This suggests that biological factors may play a more dominant role than anatomical characteristics in determining prognosis in TNBC, and that conventional clinicopathological variables may underestimate true biological aggressiveness.

The patient profile itself reveals much about TNBC in developing countries. Most patients were aged 40 years or older at 82.8 percent, had a normal body mass index below 25 at 82.8 percent, and presented with locally advanced disease at 72.4 percent. Nearly two-thirds had Grade III tumors, and 72.4 percent showed a high Ki-67 index of 20 percent or greater, indicating elevated proliferative activity consistent with basal-like TNBC biology. Late-stage presentation reflects persistent barriers to early detection in Indonesia, including low health literacy and limited access to diagnostic services, contributing directly to poorer survival outcomes since advanced TNBC typically has a 5-year survival below 50 percent.

The study has limitations that warrant caution. The cohort was small, drawn from a single institution, and dominated by locally advanced disease, which may not fully represent the broader spectrum of TNBC. Statistical power to detect significant associations was limited, and generalization to early-stage populations requires validation. Nevertheless, the findings suggest that incorporating vimentin immunostaining into routine diagnostic panels could enhance risk stratification and personalized management, particularly in tertiary centers. Patients with high vimentin levels may benefit from EMT-inhibitory strategies such as TGF-beta or STAT3 blockade, which are being explored in TNBC trials. Future prospective multicenter studies with larger and more heterogeneous cohorts are needed to confirm the prognostic significance of vimentin expression and to translate these findings into clinical practice.

Subject of Research: Triple-negative breast cancer

Article Title: The Prognostic Role of Vimentin Expression in Triple‐Negative Breast Cancer: A Retrospective Cohort Study

Article References: Danil Yulian, E., Hellyanti, T., & Rowika, K. H. L. (2026). The Prognostic Role of Vimentin Expression in Triple‐Negative Breast Cancer: A Retrospective Cohort Study. Cancer Reports, 9(10), Article e70632. https://doi.org/10.1002/cnr2.70632

Image Credits: AI Generated

DOI: 10.1002/cnr2.70632

Keywords: vimentin, triple-negative breast cancer, TNBC, epithelial-mesenchymal transition, EMT, Ki-67, immunohistochemistry, prognosis, overall survival, biomarker, Prognostic, Role

The team’s central question was deceptively simple: can the merger of two genetically identical, non-malignant cells set in motion the kind of genome-wide upheaval that is normally associated with tumor initiation? The answer, documented across karyotypic, morphological, transcriptomic and phenotypic analyses, is a resounding yes. The researchers labeled the nuclei of M13SV1 human breast epithelial cells with two different fluorescent histone tags, H2B-GFP and H2B-mCherry, and co-cultured the two populations. Any cell that spontaneously fused would carry both colors in its nucleus, allowing the team to pick out and propagate individual hybrid clones derived from nothing more than unscheduled fusion between healthy cells.

Flow cytometry revealed that these hybrids began life near-tetraploid, carrying roughly double the normal complement of chromosomes, and were already saturated with DNA damage. Using the γ-H2AX marker, which flags double-strand breaks, the researchers found that up to ten percent of cells in the hybrid populations displayed damage foci, concentrated overwhelmingly in the S and M phases of the cell cycle. This is a crucial detail: it suggests that most of the damage arises during DNA replication and is carried straight into mitosis without repair. When the team visualized dividing hybrid cells under a confocal laser-scanning microscope, they saw a gallery of mitotic horrors, including multipolar spindles, lagging chromosomes and extrachromosomal DNA, with γ-H2AX foci present in every dividing cell examined.

Whole-genome doubling is far from a rare curiosity in human cancer. Pan-cancer genome studies indicate that approximately 30 to 37 percent of cancer cells within solid tumors carry a tetraploid karyotype resulting from a whole-genome doubling event, which can arise through endocycling, mitotic slippage, endomitosis, cytokinesis failure or cell fusion. Cells with more than two chromosome sets are predisposed to chromosomal instability because extra centrosomes and oversized genomes create fertile ground for segregation errors. Merotelic kinetochore attachments, in which microtubules from opposing spindle poles compete for the same chromosome, produce lagging chromosomes that become trapped in the cleavage furrow and eventually form their own micronuclei. Because micronuclei possess defective nuclear laminae, the DNA inside them suffers strand breaks and large-scale rearrangements, a process that can culminate in chromothripsis, the shattering and random reassembly of entire chromosomes.

Perhaps the most provocative finding of the new study concerns what happened when the hybrid clones were passaged over the long term. Between early passages (4 to 6) and late passages (20 to 22), all three hybrid clones underwent a ploidy reduction, shifting from near-tetraploid to near-triploid or, in one case, a mixed near-triploid and near-diploid state. Crucially, this reduction in genome size was not accompanied by any reduction in DNA damage. The burden of lesions remained constant or even increased, and the heaviest damage continued to accumulate during replication and mitosis. The researchers interpret this as evidence of ploidy-dependent replication stress: a doubled genome demands nucleotides and replication factors that the cell cannot supply in proportion, causing replication forks to stall and collapse, and generating the double-strand breaks that fuel ongoing chromosomal instability.

Single-cell fate tracking painted an equally dramatic picture. Compared with diploid parental cells, in which roughly one fifth of divisions went awry and most aberrant progeny promptly died, the hybrid clones exhibited aberrant mitotic outcomes in 40 to 60 percent of tracked divisions. These included multipolar division, endoreplication, failed cytokinesis and even refusion, in which daughter cells merged back together after mitosis. The hybrids also survived these errors far more successfully than their diploid parents, a resilience the authors attribute to their extra chromosome copies, which buffer against the lethal loss of essential genes. Over time, the hybrid populations even regained proliferative capacity, with late-passage clones outgrowing the parental cells, suggesting that an ongoing post-hybrid selection process was actively favoring faster-growing subclones.

Morphometric analysis added another layer of intrigue. Early-passage hybrids were enlarged by only 15 to 40 percent in cell area despite carrying roughly double the DNA, and their nuclei were 20 to 60 percent larger than those of diploid controls. As passages accumulated and ploidy fell, both cell and nuclear size shrank in a hybrid-clone-dependent manner, with one clone’s cell area returning almost exactly to the diploid baseline even as its nucleus remained enlarged. The team also documented a striking degree of nuclear deformation, with multi-lobulation, invagination and nuclear blebbing persisting across all passages. A Pearson correlation analysis revealed that the degree of nuclear deformation was positively correlated with the amount of DNA damage, particularly during the S and M phases, supporting the idea that a distorted nuclear architecture and genomic instability reinforce one another in a vicious cycle.

Transcriptomic profiling by RNA sequencing exposed the malignant potential simmering beneath this chromosomal chaos. All three hybrid clones shared 427 differentially expressed genes relative to the parental cells, and enrichment analysis showed that genes linked to epithelial-mesenchymal transition, or EMT, hypoxia, p53 signaling and xenobiotic metabolism were consistently upregulated. Western blots confirmed that the hybrids had lost the epithelial marker E-cadherin in two clones and gained the mesenchymal markers N-cadherin and vimentin, hallmarks of a phenotypic switch toward motility and invasiveness. Functional assays backed this up: hybrid clones formed more colonies and larger mammospheres than parental cells, and two clones showed markedly enhanced migratory and invasive behavior. Notably, EMT gene expression was enriched only in late-passage hybrids, suggesting that the mesenchymal switch is a subclonal evolutionary process rather than an immediate consequence of fusion.

One chromosomal region stood out in the transcriptional mapping. The p36 locus on chromosome 1 was significantly downregulated in every hybrid clone, and within the 1p36.33 to 1p36.31 segment, the tumor suppressor gene AJAP1 was the most heavily silenced, with log2 fold changes ranging from minus six to minus ten. This is a finding with clear clinical resonance. Deletion of 1p36 is a common event across many cancer types, and analysis of the TCGA pan-cancer dataset showed that copy number loss of this region is associated with worse overall survival. AJAP1 expression was lower in tumor tissue than in healthy tissue, lowest of all in metastatic lesions, and reduced AJAP1 levels correlated with higher patient mortality. Because AJAP1 is known to inhibit EMT, its near-complete loss in the hybrids fits neatly with their mesenchymal, migratory phenotype.

Taken together, the study frames atypical cell fusion as a potential catastrophic event in carcinogenesis, comparable in its genomic consequences to chromothripsis or chromoplexy, which pan-cancer analyses have detected in more than a fifth of tumors. A single fusion event instantly doubles the genome, disrupts the cytoplasm, duplicates centrosomes and forces the hybrid cell through a first mitosis in which parental genomes collide, unleashing genome chaos at a macroevolutionary pace. The surviving hybrids, buffered by their extra chromosomes and shaped by relentless selection, drift toward smaller, faster-growing, more motile subclones with premalignant transcriptional signatures. While the researchers caution that further work, including limited-dilution and transplantation experiments, is needed to confirm true tumor-initiating capacity, the message is clear: the road to cancer may sometimes begin not with a mutation in a single gene, but with two healthy cells making the fateful decision to become one.

Subject of Research: Spontaneous fusion of non-transformed breast epithelial cells inducing genome chaos, chromosomal instability and premalignant hybrid phenotypes

Article Title: Atypical fusion among non-malignant cells: Unveiling the link between post-fusion-induced genome chaos and cancer initiation

Article References: Weiler, J., Topsis, G. R., & Dittmar, T. (2026). Atypical fusion among non-malignant cells: Unveiling the link between post-fusion-induced genome chaos and cancer initiation. Cancer Cell International, 26(1), Article 338. https://doi.org/10.1186/s12935-026-04466-1

Image Credits: AI Generated

DOI: 10.1186/s12935-026-04466-1

Keywords: cell fusion, genome chaos, chromosomal instability, polyploidy, whole-genome doubling, breast epithelial cells, EMT, micronuclei, AJAP1, 1p36 deletion, cancer initiation, hybrid cells

The strategy hinges on two molecular villains that have long frustrated oncologists. The first is enhancer of zeste homolog 2, or EZH2, the catalytic engine of the Polycomb repressive complex 2, which decorates histone proteins with repressive methylation marks and helps lock tumor-suppressor genes into silence. EZH2 is frequently overexpressed in colorectal cancer and has been linked to advanced disease, poor survival, and resistance to chemotherapy. The second is signal transducer and activator of transcription 3, or STAT3, a signaling hub whose hyperactivation drives proliferation, survival, invasion, and immune evasion. Crucially, these two are not independent actors: EZH2 activity has been shown to sustain STAT3 phosphorylation, creating a self-reinforcing loop that pushes cancer cells toward increasingly aggressive behavior.

Enter microRNA-124, a small regulatory RNA best known for its roles in the nervous system but increasingly recognized as a formidable tumor suppressor. The researchers began by mining publicly available clinical datasets, including the GEO repository entry GSE156719, and confirmed that miR-124 is significantly downregulated in colorectal cancer tissues. Strikingly, the loss of this microRNA correlated with more advanced tumor stages and poorer patient prognosis, echoing earlier independent reports that reduced miR-124 expression serves as an independent prognostic factor in colorectal cancer patients. Prior mechanistic work had established that miR-124 can directly target the EZH2 transcript, making it an attractive therapeutic cargo—if only it could be delivered effectively.

That delivery problem is precisely where the new study makes its mark. MicroRNAs are notoriously fragile molecules: injected freely into the bloodstream, they are rapidly degraded by circulating nucleases, fail to cross cell membranes, and get filtered out by the kidneys before reaching their targets. Synthetic nanoparticles can protect RNA cargo, but they often trigger immune reactions, accumulate in the liver and spleen, and lack any built-in ability to home in on tumors. The Tehran-led team instead turned to small extracellular vesicles, natural nanoscale membrane sacs ranging roughly from 30 to 150 nanometers, secreted by virtually all cells and acting as intercellular couriers for proteins, lipids, and genetic material.

Mesenchymal stem cells are particularly generous producers of these vesicles, and their cargo packets come with several built-in advantages. They are biocompatible, minimally immunogenic, stable in circulation, and—thanks to surface molecules inherited from their parent cells—they display a natural tropism for tumor tissue, navigating toward the inflammatory, hospitable terrain of the tumor microenvironment. To weaponize this delivery system, the researchers used lentiviral transduction to coax mesenchymal stem cells into overproducing miR-124, so that the microRNA became efficiently packaged into the vesicles the cells subsequently released. The result was a batch of engineered MSC-derived small extracellular vesicles, dubbed MSC-sEV-miR-124, brimming with the tumor-suppressive cargo.

Laboratory tests on colorectal cancer cells showed that the vesicles were readily internalized, delivering functional miR-124 into the recipient cells and restoring it to levels the cancer had suppressed. Once inside, miR-124 bound to its target sequence on EZH2 messenger RNA, directly downregulating the epigenetic silencer. The consequences cascaded through the cell: with EZH2 suppressed, STAT3 phosphorylation dropped, weakening the oncogenic signaling loop. Treated cancer cells lost their capacity for unrestrained proliferation, their migratory prowess diminished, and the epithelial-mesenchymal transition—the cellular makeover that lets tumor cells detach, invade surrounding tissue, and seed metastases—was visibly reversed. The team also observed that the treatment pushed cancer cells toward apoptosis, the controlled self-destruction program that malignant cells typically resist.

Perhaps the most clinically tantalizing finding emerged from combination experiments with 5-fluorouracil, a chemotherapy backbone drug for colorectal cancer. MSC-sEV-miR-124 sensitized the cancer cells to the drug and reversed chemoresistance, an effect the researchers attribute to the downregulation of EZH2, which earlier studies have implicated in therapy resistance through mechanisms including the suppression of autophagy. If this chemosensitizing effect holds up in further models, engineered vesicles could eventually be paired with existing drug regimens rather than replacing them, potentially lowering required doses and reducing the toxic side effects that plague current protocols.

The in vivo experiments provided the crucial proof of concept. When the engineered vesicles were administered in a xenograft model using BALB/c mice bearing colorectal tumors, tumor growth was significantly reduced compared with controls. Molecular analysis of the excised tumors confirmed that the intended mechanisms had engaged in living tissue: EZH2 and STAT3 signaling were downregulated, the proliferation marker Ki-67 diminished, and epithelial-mesenchymal transition markers receded. The vesicles had not only reached their targets but had executed the genetic program they were designed to deliver, suppressing the dual EZH2-STAT3 axis from within the tumor itself.

Significant hurdles remain before such a therapy could approach the clinic. Manufacturing extracellular vesicle therapeutics at pharmaceutical scale demands rigorous quality control over vesicle size, cargo loading efficiency, purity, and batch consistency—challenges that recent reviews of extracellular vesicle-based drug development have flagged as central to the field. Questions about long-term safety, dosing, biodistribution, and the behavior of mesenchymal stem cell-derived products in diverse patient populations will all need systematic answers. The authors themselves frame the work explicitly as proof of concept in murine models, noting that EV-based miRNA delivery warrants further investigation as a strategy to modulate the tumor microenvironment and overcome the epigenetic and oncogenic signaling barriers that currently limit colorectal cancer therapy.

Even so, the study adds an important datapoint to one of the most exciting convergences in modern oncology: the marriage of RNA therapeutics with biomimetic nanodelivery. By exploiting the tumor-homing talent of stem cell vesicles to smuggle a master-regulatory microRNA past the body’s defenses, and by aiming that microRNA at two intertwined pillars of cancer aggression simultaneously, the research outlines a template that could extend well beyond colorectal cancer. As the field of engineered extracellular vesicles matures, therapies that once lived only in molecular biology textbooks may be inching closer to the infusion clinic.

Subject of Research: Engineered mesenchymal stem cell-derived extracellular vesicles delivering miR-124 as a therapy for colorectal cancer

Article Title: Engineered mesenchymal stem cell-derived small extracellular vesicles delivering miR-124 suppress colorectal cancer progression through EZH2 downregulation and attenuation of STAT3 signaling

Article References: Behzadi Andouhjerdi, R., Hosseini, F., Hosseinzadeh, N., Zivari, S., Salkhordeh, S., Mohammadi, M., Rahmani, M., Hatami, P., Naji, S. S., Pourtahmasebi, M., Khanabadi, M., Golbahar, M., Hajesmaeili, A., Eftekhari, P., Asbaghi, M., Norouz-Nejad, A., Akbarabadi, P., Ghazimoradi, M. H., Babashah, S., & Piravar, Z. (2026). Engineered mesenchymal stem cell-derived small extracellular vesicles delivering miR-124 suppress colorectal cancer progression through EZH2 downregulation and attenuation of STAT3 signaling. Medical Oncology, 43(11), Article 318. https://doi.org/10.1007/s12032-026-03418-z

Image Credits: AI Generated

DOI: 10.1007/s12032-026-03418-z

Keywords: colorectal cancer, extracellular vesicles, mesenchymal stem cells, miR-124, EZH2, STAT3, epigenetics, microRNA delivery, 5-fluorouracil, chemoresistance, EMT, xenograft model

MicroRNAs are tiny single-stranded RNA molecules, roughly twenty-two nucleotides long, that act as post-transcriptional brakes on gene expression. By binding to messenger RNAs, a single microRNA can simultaneously dampen dozens of target genes, which makes them powerful coordinators of cellular programs. The miR-34 family, which includes miR-34a and miR-34c, is positively regulated by the tumor suppressor p53 and is well established as a metastasis-suppressing force in many cancers, including adult glioblastoma. Because pediatric high-grade gliomas frequently harbor inactivating mutations in the TP53 gene, the researchers suspected that the miR-34 axis might be crippled in these tumors—but until now, its role had never been examined.

The team worked with two cell line models derived from molecularly distinct patients. SF188 came from a biopsy of an eight-year-old boy, while KNS42 was established from an aggressive tumor resected from a sixteen-year-old male and carries the distinctive H3F3A G34V histone mutation. Both lines express glial markers and harbor point mutations in p53. Using quantitative PCR, the researchers found that both miR-34a and miR-34c were significantly downregulated in the tumor cell lines compared with normal human astrocytes. They then turned to a public tumor dataset, GEO accession GSE63319, comprising eleven pHGG-4 cases and four age-matched controls, and found that mean miR-34c expression was markedly reduced in the patient tumors, while miR-34a was low in a subset of samples.

With the suppressors confirmed to be missing, the researchers reintroduced them. They transfected the cells with synthetic miR-34a or miR-34c mimics, or with a scrambled oligonucleotide as a negative control, and measured the consequences. The results were striking. Ectopic upregulation of either microRNA reduced cell viability by roughly forty percent in KNS42 cells and sixty percent in SF188 cells. Colony formation assays, in which single cells must proliferate into visible colonies of at least fifty cells over several weeks, told the same story: colony formation fell by 63 to 69 percent in KNS42 cells and by 54 to 62 percent in SF188 cells, depending on which microRNA was restored.

The most clinically meaningful effects concerned the tumor’s infiltrative behavior, the property that makes complete surgical removal nearly impossible. In scratch wound healing assays, restoring miR-34a or miR-34c inhibited gap closure in SF188 cells by 29 and 46 percent respectively. In transwell migration assays, miR-34a slashed KNS42 cell migration by 73 percent, while miR-34c cut it by 42 percent. Invasion through a basement membrane extract was similarly blunted: miR-34a reduced invasiveness by 56 percent in SF188 and 57 percent in KNS42 cells, and miR-34c by 43 and 46 percent. In other words, both microRNAs acted as broad brakes on the very behaviors that drive tumor spread through a child’s brain.

To understand how these small RNAs achieved such wide-ranging effects, the team mapped their impact on the molecular machinery of survival and proliferation. Both microRNAs downregulated the anti-apoptotic gene BCL-2 and upregulated the pro-apoptotic genes PUMA and, in some cases, BAX and BIM, while inducing the cell cycle arrest gene P21. They also suppressed CDK6, a driver of cell cycle progression, and reduced the potent oncogenes N-MYC and C-MYC, though in a pattern that differed between the two microRNAs and the two cell lines. Notably, these targeting patterns diverged from those previously reported in other cancers, underscoring that the miR-34 family operates through non-redundant, context-dependent pathways in pediatric glioma cells.

Perhaps the most surprising finding involved p53 itself. Although both cell lines carry point mutations in TP53, immunofluorescence staining with conformation-specific antibodies revealed that the mutant protein predominantly adopts a mutant shape in untreated cells—and that restoring either miR-34a or miR-34c shifted the protein toward its wild-type conformation in both cell lines. This conformational rescue was accompanied by a sharp drop in SIRT1, an NAD-dependent deacetylase that normally restrains p53 activation. SIRT1 mRNA was three to 3.6-fold elevated in the tumor cells relative to normal astrocytes, and both microRNAs cut its mRNA levels by roughly half while reducing protein expression by 50 to 85 percent. Together, these changes suggest that the miR-34 family can partially reactivate the cell’s central tumor-suppressive circuitry even in tumors where the guardian gene itself is mutated.

The researchers then probed the epithelial–mesenchymal transition, or EMT, the cellular program by which tumor cells lose adhesion and polarity and gain migratory, invasive, and stem-like properties. In central nervous system tumors, EMT-like mechanisms mirror those of epithelial cancers and are thought to underpin much of pHGG-4 aggressiveness. Both microRNAs targeted multiple EMT mediators, including the NOTCH1 and NOTCH2 receptors, the transcriptional repressor SNAIL1, the interleukin-6 receptor and its downstream effector STAT3, and the receptor tyrosine kinase C-MET, whose expression fell by up to 80 percent at the mRNA level. The team also detected nMET, a truncated nuclear C-MET fragment associated with malignant progression, and found it reduced as well. Downstream, miR-34c dampened phosphorylated FAK in both cell lines, while miR-34a did so only in SF188 cells. Meanwhile, the epithelial marker CDH1, encoding E-cadherin, was restored up to four-fold in KNS42 cells, and the stemness markers CD133 and NESTIN fell by 32 to 71 percent across both models.

A recurring theme throughout the study is that the two microRNAs, while producing similar phenotypic outcomes, achieved them through overlapping but non-identical molecular routes that varied between cell lines. miR-34c emerged as the broader suppressor, hitting N-MYC, C-MYC, SIRT1, nMET, and pFAK across both models, whereas miR-34a showed a particularly strong inhibitory effect on the migratory behavior of the H3F3A G34-mutated KNS42 line. This cell line dependence reinforces the study’s central message: epigenetic dysregulation, rather than a short list of recurrent genetic alterations, is a central engine of pHGG-4 aggressiveness, and correcting it can dismantle multiple malignant programs at once.

The findings also arrive amid a cautious resurgence of interest in microRNA therapeutics. The first-in-human trial of MRX34, a liposomal miR-34a mimic tested in non-central nervous system malignancies, produced encouraging antitumor responses before being halted over immune-mediated adverse events. Challenges such as delivery to brain tissue, variable expression, and immune safety remain formidable. Still, by demonstrating that two naturally occurring tumor suppressors can simultaneously curb survival, proliferation, migration, invasion, and stemness in an otherwise untreatable pediatric cancer, this work lays a rational foundation for miR-34-based therapeutic strategies—and offers a glimmer of hope for children facing one of medicine’s most devastating diagnoses.

Subject of Research: The role of the microRNAs miR-34a and miR-34c as tumor suppressors regulating aggressiveness in pediatric high-grade glioma grade 4

Article Title: The potential role of miR-34a and miR-34c in the regulation of pediatric high-grade glioma 4 aggressiveness

Article References: Rogachevsky, D., Yalon, M., Mehrian-Shai, R., & Toren, A. (2026). The potential role of miR-34a and miR-34c in the regulation of pediatric high-grade glioma 4 aggressiveness. Pediatric Research. https://doi.org/10.1038/s41390-026-05518-y

Image Credits: AI Generated

DOI: 10.1038/s41390-026-05518-y

Keywords: pediatric high-grade glioma, miR-34a, miR-34c, microRNA, epigenetics, p53, SIRT1, EMT, C-MET, tumor suppressor, glioblastoma, miRNA therapeutics

The Notch pathway is one of the most evolutionarily conserved signaling systems in multicellular organisms. In mammals it comprises four transmembrane receptors, NOTCH1 through NOTCH4, and five membrane-bound ligands of the Delta-like and Jagged families. Signaling is unusual in that it does not rely on a second-messenger cascade: when a ligand on a neighboring cell engages a Notch receptor, the receptor undergoes sequential cleavage, first by ADAM-family metalloproteinases and then by the γ-secretase complex. This releases the Notch intracellular domain (NICD), which translocates to the nucleus and binds the DNA-associated transcription factor CSL, together with the coactivator Mastermind-like (MAML), to switch on target genes. Foremost among these are the Hairy and Enhancer of Split (HES) and HEY family transcriptional repressors, which in turn control genes governing proliferation, differentiation, and survival.

Because Notch sits at the helm of decisions about when cells divide, when they differentiate, and when they die, even modest dysregulation can be dangerous. The review emphasizes that abnormal Notch activity has been implicated in cell proliferation, resistance to apoptosis, maintenance of stem-like cell populations, epithelial–mesenchymal transition (EMT), and immune evasion. In normal tissue these processes are carefully balanced; in cancer they are the engine of tumor growth and spread. The authors’ central thesis is that oncoviruses exploit this pathway deliberately, co-opting its transcriptional output to create a cellular environment favorable to viral persistence and, ultimately, malignant transformation.

HPV provides one of the clearest examples. The viral oncoproteins E6 and E7, which drive degradation of the tumor suppressors p53 and pRB, also interact with Notch signaling in ways that shift the pathway’s effects. Notch signaling in HPV-infected keratinocytes can cooperate with viral gene expression to sustain proliferation and block terminal differentiation—the very process the virus must arrest to complete its life cycle. The review notes that HPV-positive lesions show altered expression of Notch receptors and ligands, and that the interplay between E6/E7 and NICD-dependent transcription blurs the line between the productive viral life cycle and neoplastic progression, particularly in cervical carcinogenesis.

HTLV-1, the causative agent of adult T-cell leukemia/lymphoma (ATLL), takes a different route. Its trans-activator protein Tax is a potent manipulator of host transcription factors, and the review describes how Tax-driven activation of NF-κB and AP-1 converges with Notch signaling to keep infected T cells in a proliferative, apoptosis-resistant state. The HTLV-1 basic leucine zipper factor (HBZ), expressed from the antisense strand, further entrenches this program, supporting the survival and expansion of leukemic clones. The same virus is also associated with HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), underscoring that Notch manipulation has consequences beyond cancer.

Among the herpesviruses, EBV and KSHV display especially intricate relationships with Notch. EBV latency proteins, including the Epstein–Barr nuclear antigens (EBNAs) and latent membrane proteins (LMPs), modulate Notch receptor processing and downstream transcription; LMP1 and LMP2A signaling intersects with NICD-mediated gene activation in nasopharyngeal carcinoma and EBV-associated lymphoid malignancies. KSHV, the etiologic agent of Kaposi’s sarcoma, deploys its own arsenal: the latency-associated nuclear antigen (LANA), the viral FLICE-inhibitory protein (vFLIP), and the viral G protein-coupled receptor (vGPCR) each contribute to Notch pathway activation, fostering the angiogenesis, inflammation, and cell survival that characterize the tumor. The replication and transcription activator (RTA), which controls the viral lytic switch, adds a further layer of regulation linking viral life cycle dynamics to host signaling.

The hepatitis viruses illustrate that even viruses not conventionally classed as DNA-tumor viruses participate in this crosstalk. HBV’s X protein (HBx) promotes Notch activation in hepatocytes, contributing to the proliferative and survival signals that underlie hepatocellular carcinoma, while HCV proteins engage the pathway in ways that reinforce chronic inflammation and fibrogenic progression toward malignancy. In both cases, the review suggests that Notch dysregulation acts as a bridge between chronic viral injury and the molecular events of carcinogenesis, potentially offering biomarkers that distinguish progressing lesions from indolent disease.

A recurring theme across all six viruses is context dependence. Notch can behave as an oncogene in some tissues and as a tumor suppressor in others, and the review stresses that the outcome of viral manipulation depends on cell type, the differentiation state of the infected cell, and which receptors and ligands are expressed. Additional layers of control—including microRNAs, long non-coding RNAs, the E3 ubiquitin ligase FBXW7 that targets NICD for degradation, and fringe glycosyltransferases such as Manic Fringe that modify ligand–receptor affinity—determine where the signaling dial sits. Viruses appear to nudge these layers simultaneously, producing a coherent pro-tumor transcriptional state rather than a single wholesale switch.

The therapeutic implications are significant. γ-secretase inhibitors (GSIs), originally developed for Alzheimer’s disease and already tested in Notch-driven T-cell leukemias, emerge as a class of compounds that could, in principle, sever the viral exploitation of the pathway. The review also points toward Notch-related biomarkers for early detection and risk stratification in virus-associated cancers, and toward combination strategies in which antiviral therapy is paired with pathway-targeted agents. However, the authors caution that Notch’s dual roles and its importance in normal stem cell maintenance demand careful dosing and tissue-specific approaches.

The review closes by flagging the field’s unresolved questions: the precise order in which viral proteins and Notch activation act during multi-step carcinogenesis, the contribution of Notch to immune evasion in virally infected tissue, and whether Notch signatures can reliably predict transformation in premalignant lesions. What is already clear, the authors conclude, is that deeper mechanistic understanding of virus–Notch crosstalk could reshape basic research on viral carcinogenesis, yield diagnostic biomarkers, and guide the next generation of targeted antiviral and anti-cancer therapies. As the list of virus-associated malignancies continues to grow, the Notch pathway looks increasingly like common ground on which these diverse pathogens meet.

Subject of Research: Dysregulation of the Notch signaling pathway by human oncogenic viruses in carcinogenesis

Article Title: Oncogenic human viruses and notch signaling: a focus on key dysregulation within the NOTCH pathway

Article References: Faghihloo, E., & Tavakolian, S. (2026). Oncogenic human viruses and notch signaling: a focus on key dysregulation within the NOTCH pathway. Virology Journal. https://doi.org/10.1186/s12985-026-03324-w

Image Credits: AI Generated

DOI: 10.1186/s12985-026-03324-w

Keywords: Notch signaling, oncogenic viruses, HPV, HTLV-1, EBV, KSHV, HBV, HCV, carcinogenesis, NICD, gamma-secretase inhibitors, EMT

Circular RNAs, or circRNAs, are a peculiar class of non-coding molecules. Unlike ordinary linear RNAs, their ends are covalently joined into a closed loop, which makes them extraordinarily stable and resistant to the exonucleases that rapidly degrade most RNA in cells and body fluids. That stability, combined with their frequent dysregulation in tumors, has made circRNAs a focus of intense cancer research over the past decade. The new work extends this interest into a specific and clinically important niche: bladder cancers driven by tobacco exposure.

The research team began by examining clinical samples from bladder cancer patients and found that circ55033 was highly expressed in tumors from patients who smoked, compared with matched adjacent non-cancerous tissue. This smoking-associated enrichment was the first clue that the molecule might not simply be a bystander in the disease but an active participant in smoke-related tumor biology. The finding builds on the group’s earlier studies, which showed that cigarette smoke extract can trigger epithelial-mesenchymal transition, or EMT, in bladder cells through signaling pathways such as ERK1/2, ERK5 and MAPK, and can also support cancer stem cell properties through Sonic Hedgehog signaling.

EMT is a developmental program that cancer cells hijack: epithelial cells, normally tightly anchored to their neighbors, lose their polarity and acquire the motile, spindle-shaped characteristics of mesenchymal cells. In tumors, this shift is strongly associated with invasion, metastasis and resistance to therapy. Closely intertwined with EMT is the acquisition of cancer stemness, the capacity of a subset of tumor cells to self-renew, seed new tumors and survive chemotherapy. The new study demonstrates that cigarette smoke induces both of these malignant programs in bladder cancer cells, and that exosome-transported circ55033 is a critical mediator of the effect.

Exosomes are nanoscale vesicles, typically 30 to 150 nanometers in diameter, released by virtually all cell types into the extracellular space. Far from being cellular refuse, they act as intercellular couriers, ferrying proteins, lipids and RNA cargo between cells, including between tumor cells and their microenvironment. In the experiments reported, bladder cancer cells treated with cigarette smoke extract released exosomes enriched in circ55033, and these smoke-conditioned vesicles, designated CSE-Ex, could transfer the molecule to recipient bladder cancer cells. Once delivered, the cargo promoted EMT and stem-like behavior in the receiving cells, effectively spreading the smoke-induced malignant phenotype through the tumor cell population.

To confirm that circ55033 was the functional ingredient rather than a passenger, the researchers used small interfering RNAs to knock down the molecule and observed that the smoke-driven enhancement of EMT markers and stemness traits was blunted. Conversely, elevating circ55033 reproduced the oncogenic effects. This gain- and loss-of-function logic, combined with the exosome transfer experiments, places circ55033 squarely in the causal pathway between smoke exposure and tumor aggressiveness.

The mechanistic centerpiece of the study is the identification of how circ55033 exerts its influence. Using complementary approaches, including wild-type and mutant binding constructs, the team showed that circ55033 acts as a molecular sponge for miR-1286, a microRNA. MicroRNAs are short regulatory RNAs that normally bind target messenger RNAs and suppress their translation or promote their degradation, often restraining tumor-promoting genes. By sequestering miR-1286, circ55033 relieves this restraint, allowing oncogenic programs downstream of the microRNA to proceed. This competing endogenous RNA mechanism, in which a circular RNA titrates away a suppressive microRNA, is a recurring theme in circRNA biology and has now been pinned down in the context of smoking-related bladder cancer.

Perhaps the most clinically tantalizing result concerns diagnosis. Because circRNAs are stable and exosomes protect their cargo from degradation in the bloodstream, circulating exosomal circRNAs are attractive candidates for liquid biopsy, the growing effort to detect and monitor cancer through a simple blood draw rather than invasive tissue sampling. The researchers found that exosomal circ55033 in patient serum exhibited preliminary diagnostic capacity, evaluated with receiver operating characteristic analysis, suggesting that the molecule could eventually serve as a non-invasive biomarker for identifying smoking-related bladder cancer. The authors are careful to frame this as a preliminary candidate; larger validation cohorts will be needed before such a test could approach clinical use, particularly given that bladder cancer surveillance already relies on urine-based markers and cystoscopy.

The therapeutic implications are equally noteworthy. If exosomal circ55033 is a genuine driver of smoke-induced EMT and stemness, then intercepting it, whether by blocking exosome uptake, silencing the circRNA with RNA-based therapeutics, or restoring miR-1286 activity, could in principle deprive smoke-exposed tumors of an important aggressiveness mechanism. Exosome-mediated delivery is itself being explored as a gene therapy platform for bladder cancer, which hints at a future in which the same vesicles that carry oncogenic signals could be engineered to carry therapeutic ones. Such strategies remain firmly preclinical, but the study provides a concrete molecular target around which they could be designed.

The work also fits into a broader re-evaluation of how environmental carcinogens act. Rather than merely damaging DNA directly, cigarette smoke appears to reshape the regulatory RNA landscape of urothelial cells and to weaponize the vesicular communication network between them, spreading pro-malignant instructions through the tissue. With bladder cancer carrying high morbidity and mortality worldwide, and smoking remaining its dominant modifiable cause, dissecting these RNA-mediated circuits offers both mechanistic insight and a pipeline of candidate biomarkers. For now, circ55033 joins a growing roster of exosomal circular RNAs implicated in urological malignancies, and its journey from laboratory observation to validated diagnostic and therapeutic tool will depend on the validation studies that must follow.

Subject of Research: The role of exosomal circular RNA circ55033 in cigarette smoke-induced bladder cancer progression via EMT and cancer stemness regulation

Article Title: Exosomal circ55033 promotes cigarette smoke-induced bladder cancer by modulating EMT and stem cell properties

Article References: Geng, H., Wu, Y., Ma, J., Zhang, W., Liang, Z., & Zhang, T. (2026). Exosomal circ55033 promotes cigarette smoke-induced bladder cancer by modulating EMT and stem cell properties. Medical Oncology, 43(11), Article 326. https://doi.org/10.1007/s12032-026-03444-x

Image Credits: AI Generated

DOI: 10.1007/s12032-026-03444-x

Keywords: bladder cancer, cigarette smoke, exosomes, circ55033, circular RNA, miR-1286, EMT, cancer stem cells, liquid biopsy, biomarker, Medical Oncology, non-coding RNA

To understand why this pathway has attracted such intense scrutiny, it helps to look at its molecular architecture. In its canonical form, NF-κB dimers—most commonly composed of the p65 (RelA) and p50 subunits—sit idle in the cytoplasm, tethered by inhibitory IκB proteins. When pro-inflammatory cytokines such as tumour necrosis factor alpha or interleukin-1 engage their receptors, a signalling cascade triggers the IκB kinase (IKK) complex, whose regulatory NEMO subunit assembles a ubiquitin-dependent signalosome. IKK then phosphorylates IκBα, marking it for proteasomal destruction and freeing NF-κB to enter the nucleus and switch on hundreds of target genes. The non-canonical arm works differently: NF-κB-inducing kinase (NIK) activates an IKKα-dependent process that processes the precursor p100 into p52, generating RelB/p52 dimers that control a distinct set of genes involved in lymphoid organogenesis, immune cell function and, crucially, tumour-microenvironment communication. The review emphasises that these two arms are not isolated modules but a single integrated system, with feedback loops, shared components such as the fourth IκB protein, and cross-regulation that shapes both the timing and the composition of the transcriptional response.

What makes NF-κB particularly treacherous in breast cancer is that its behaviour varies dramatically across molecular subtypes. The review systematically dissects luminal A, luminal B, HER2-enriched and basal-like or triple-negative disease, showing that the magnitude and biological consequences of NF-κB activation are anything but uniform. In hormone receptor-positive tumours, NF-κB engages in intimate crosstalk with the oestrogen receptor alpha. Landmark work cited in the review demonstrated that an IKKα-dependent transcriptional complex is required for oestrogen receptor-mediated gene activation, meaning that the inflammatory pathway is not merely a parallel route to malignancy but is physically embedded in the machinery that oestrogen-responsive tumours depend upon. This entanglement helps explain why NF-κB activity is repeatedly implicated in endocrine therapy resistance: as tumours evolve under the selective pressure of anti-oestrogen drugs, they appear to lean increasingly on inflammatory signalling to maintain survival programmes that the blocked receptor can no longer fully provide.

In HER2-positive disease, the picture shifts toward cooperation with the HER2-PI3K-AKT axis, one of the most consequential growth-factor pathways in this aggressive subtype. Constitutive activation of PI3K-AKT signalling can potentiate NF-κB-dependent transcription, reinforcing anti-apoptotic gene expression and supporting the survival of tumour cells exposed to HER2-targeted agents. The review also highlights experimental evidence that blocking NF-κB can enhance the responsiveness of mammary tumours to JAK inhibitors, suggesting that inflammatory and cytokine signalling pathways converge in ways that single-agent approaches fail to fully exploit. For triple-negative breast cancer—the subtype with the fewest targeted options—NF-κB assumes an even more central role. Studies using small inhibitory RNAs in oestrogen receptor-negative cell lines showed that suppressing the pathway impairs proliferation and survival, while IKK inhibition with compounds such as BMS-345541 has been reported to suppress breast tumorigenesis and metastasis by targeting GD2-positive cancer stem cell populations, the self-renewing cells widely believed to seed relapse and metastatic spread.

Perhaps the most clinically resonant section of the review concerns epithelial-mesenchymal transition, the cellular reprogramming that allows epithelial tumour cells to acquire motility, invasiveness and stem-like properties. NF-κB has been shown to regulate the expression of key EMT genes in breast cancer cells, effectively serving as a transcriptional gatekeeper for the plasticity that underpins metastasis. This connects directly to the inflammatory cytokine network: interleukin-1 signalling through NF-κB has been shown to be required for tumour invasiveness and angiogenesis in experimental models, and endogenous production of interleukin-1 beta by breast cancer cells has been demonstrated to drive metastasis and colonisation of the bone microenvironment in patient-derived systems. In other words, NF-κB does not merely respond to inflammation—it helps tumour cells manufacture their own inflammatory niche, a self-reinforcing loop that promotes dissemination to bone, the most common site of breast cancer metastasis.

The tumour microenvironment adds another layer of complexity. The review devotes substantial attention to macrophage heterogeneity, describing how tumour-associated macrophages can be co-opted by cancer cells to support growth and immune evasion. Recent work on an unconventional p65/p52 NF-κB module in breast tumour-associated macrophages suggests that these infiltrating immune cells use hybrid canonical-non-canonical signalling to regulate genes that shape the microenvironment in the tumour’s favour. Structural biology is beginning to illuminate how different NF-κB dimer compositions read DNA and activate transcription, with high-resolution studies of p52 homodimer-DNA complexes and NMR analyses of NF-κB-DNA interactions rationalising why specific dimer combinations produce distinct transcriptional outcomes. This structural and mechanistic granularity matters therapeutically: if different dimers control different gene programmes in different cellular compartments, then blunt pathway inhibition risks suppressing beneficial immune functions while sparing the tumour-promoting activities clinicians most want to eliminate.

Genotoxic stress introduces yet another dimension. Chemotherapy and radiotherapy work in part by damaging DNA, yet the review describes how the LUBAC ubiquitin ligase complex promotes linear ubiquitination of NEMO in response to genotoxic stress, activating NF-κB precisely when tumour cells are under attack. This damage-induced NF-κB activity can function as a survival shield, upregulating anti-apoptotic genes and helping cells repair or tolerate the damage inflicted by treatment. Consistent with this, proteasome inhibition with bortezomib has been shown to restore apoptotic factors and sensitise breast cancer cells to docetaxel in preclinical models, and clinical trials have tested bortezomib in combination with capecitabine in metastatic disease and with fulvestrant in hormone receptor-positive tumours resistant to aromatase inhibitors. A related strategy exploits SMAC mimetics, which synergise with endocrine therapy to potentiate antigen presentation and tumour regression in hormone receptor-positive breast cancer, in part by disabling NF-κB-dependent survival pathways.

Therapeutically, the review maps out a spectrum of intervention points, each with distinct trade-offs. Upstream inhibition can target receptor-level signals such as RANK/RANKL, which has attracted attention as a potential prevention target in BRCA1-mutation carriers, with a systematic review and meta-analysis now assessing the prognostic value of RANK signalling across breast cancer populations. Proteasome blockade offers a broad but toxic approach; selective NIK inhibitors are advancing as a more precise way to disable the non-canonical arm; and IKK inhibitors aim at the convergence point of both pathways. The authors also highlight emerging precision-delivery strategies and targeted-degradation concepts, including approaches that could eliminate specific NF-κB subunits rather than merely silencing their activity. Yet the review is notably candid about the translational gap: clinical data remain sparse relative to an enormous preclinical literature, and indiscriminate NF-κB inhibition carries real risks, given the pathway’s essential roles in immunity and inflammation.

The overarching message is one of disciplined optimism. NF-κB is neither a universal villain nor an untouchable guardian; it is a context-dependent network whose contribution to breast cancer depends on subtype, dimer composition, cellular compartment and the surrounding microenvironment. The review proposes a framework for subtype- and context-selective targeting, anchored in biomarker-driven patient stratification rather than blanket suppression. If that framework can be validated, the inflammatory switch that breast cancers exploit to survive, spread and resist treatment may finally become the vulnerability that clinicians have been searching for.

Subject of Research: NF-κB signalling mechanisms, crosstalk and therapeutic targeting in breast cancer

Article Title: Nuclear factor κB signalling in breast cancer: mechanisms, crosstalk and therapeutic targeting

Article References: Muthiah, B., Santha Moorthi Rajah, R. R., Kumar, A. S., Srikesavan, S., Chandrasekaran, V. N., & Priya, K. (2026). Nuclear factor κB signalling in breast cancer: mechanisms, crosstalk and therapeutic targeting. Molecular Biology Reports, 53(1), Article 1687. https://doi.org/10.1007/s11033-026-12871-y

Image Credits: AI Generated

DOI: 10.1007/s11033-026-12871-y

Keywords: NF-κB, breast cancer, canonical pathway, non-canonical pathway, IKK, NIK, HER2, triple-negative breast cancer, tumour microenvironment, therapy resistance, EMT, RANK/RANKL

The research team, based at Friedrich-Alexander Universität Erlangen-Nürnberg, designed an in vitro model that closely mimics the metabolic environment found in obese patients. In obesity and the metabolic syndrome, hyperlipidemia is a defining feature: free fatty acids released from adipose tissue circulate in the bloodstream, predominantly bound to albumin. To replicate these conditions in the laboratory, the researchers incubated six human colorectal cancer cell lines with oleic acid complexed to bovine serum albumin. The panel included three microsatellite stable lines, HT29, Caco-2 and SW480, and three microsatellite instable lines, SW48, LoVo and HCT116, each with distinct molecular backgrounds and driver mutations. Oleic acid was chosen deliberately, as it represents approximately 80 percent of the circulating monounsaturated fatty acids in human blood, making it a physiologically relevant exposure variable.

The results were striking. Within 48 hours of exposure, the cells accumulated triglycerides in a dose-dependent manner, and oil red O staining revealed the formation of abundant cytosolic lipid droplets. At the same time, the concentration of free fatty acids in the culture supernatant declined over time, confirming that the cancer cells were actively taking up the fatty acids from their surroundings. A key molecular marker of this process was perilipin-2, or PLIN2, a structural protein component of lipid droplets. Both the mRNA and protein levels of PLIN2 rose dose-dependently in the treated cells, and immunofluorescence staining visualised the enhanced formation of lipid droplets in the cytoplasm. Similar findings were observed across all six cell lines, suggesting that this lipid storage response is not restricted to a particular molecular subtype of colorectal cancer and operates independently of microsatellite stability status.

Beneath this visible lipid accumulation, the researchers documented a profound reprogramming of lipid metabolism. When exogenous fatty acids flooded the cells, the expression of enzymes responsible for de novo lipid synthesis declined. ATP citrate lyase, or ACLY, which generates cytosolic acetyl-CoA from citrate to provide building blocks for new fatty acids, showed slightly reduced mRNA expression, and fatty acid synthase, FASN, was downregulated in a dose-dependent manner. Stearoyl-CoA desaturase 1, SCD1, the key enzyme for desaturating saturated fatty acids, was also reduced, fitting with the abundant supply of monounsaturated oleate arriving from outside. In contrast, diacylglycerol-O-acyltransferase 2, DGAT2, a central enzyme of triglyceride synthesis, was increased in HT29 and Caco-2 cells, consistent with the elevated triglyceride levels. The cells, in effect, switched from manufacturing their own fat to importing and storing it.

The study also revealed an upregulation of the machinery for burning fat. Carnitine palmitoyltransferase 1A, CPT1A, the rate-limiting enzyme that shuttles long-chain fatty acids into mitochondria for beta-oxidation, increased dose-dependently at both mRNA and protein levels. Adipose triglyceride lipase, ATGL, which catalyses the first step of intracellular triglyceride hydrolysis, rose in five of the six cell lines, and the lipolytic enzymes HSL and MAGL were also elevated at the mRNA level in HT29 cells. However, functional mitochondrial stress tests painted a more nuanced picture. Oleate treatment produced only slight, statistically non-significant increases in basal respiration, and while the CPT1 inhibitor etomoxir reduced maximal respiration in HT29 cells, Caco-2 cells showed no comparable response. The authors suggest that elevated CPT1A may reflect an enhanced capacity or adaptive readiness for fatty acid oxidation, while most imported fatty acids are actually channelled into storage within lipid droplets rather than immediately combusted.

The most consequential findings concern what this lipid loading does to cancer cell behaviour. Proliferation increased dose-dependently in oleate-stimulated cells, and migratory activity, measured in Boyden chamber assays, was significantly enhanced. At the molecular level, the researchers observed a classic cadherin switch: expression of E-cadherin, the adhesive molecule that stabilises junctions between epithelial cells, was downregulated, while N-cadherin expression rose. This shift is strongly linked to greater migratory and invasive capability, as loss of E-cadherin allows cancer cells to detach from the primary tumour site. The epithelial-mesenchymal transition markers SNAIL and TWIST were also increased in HT29 cells, although these changes were more variable across the other lines. Notably, the proinflammatory cytokine interleukin-8, a marker associated with proliferation, angiogenesis, metastasis and poor outcome in colon carcinoma, increased dose-dependently in four of the six cell lines, hinting that lipid accumulation may fuel inflammatory signalling within the tumour.

To connect these laboratory observations with clinical reality, the team analysed tumour tissue from colorectal cancer patients of normal weight, with body mass index between 20 and 25, and patients with Grade I or II obesity, with BMI between 30 and 40. Obese patients showed a tendency toward higher PLIN2 expression, although the difference did not reach statistical significance in this relatively small cohort. Immunohistochemistry, however, told a clearer story: PLIN2 staining was markedly stronger in tumours from obese patients, and Ki67 staining revealed a higher number of proliferating cells in the tumours of the obese group. In silico analysis of large patient cohorts added a prognostic dimension, showing that high PLIN2 expression correlated with poorer overall and disease-free survival in colorectal carcinoma patients.

Perhaps most intriguing was the significant correlation, observed across 350 human colorectal cancer tissues from The Cancer Genome Atlas, between PLIN2 and CPT1A expression, mirroring the relationship seen in vitro. Patients with high CPT1A expression likewise showed poorer overall and disease-free survival. This association suggests that lipid storage and the capacity for fatty acid oxidation are coordinately regulated in human tumours, consistent with a state of heightened lipid flux. The authors caution that further experiments are needed to establish a causal relationship between the two proteins, and that BMI is only an indirect marker of metabolic status, since it does not directly reflect circulating free fatty acid concentrations. Functional studies and larger, independently validated cohorts incorporating detailed metabolic phenotyping will be required to confirm the clinical relevance of these findings.

The broader implications of this work extend well beyond the culture dish. The study positions exogenous fatty acid uptake as a third route, alongside de novo lipogenesis and lipolysis, by which cancer cells satisfy their high demand for fat, and one that may be particularly important in obesity-associated hyperlipidemia. The findings also resonate with related research across gastrointestinal cancers: recent work in pancreatic ductal adenocarcinoma demonstrated a functional connection between PLIN2 and CPT1A in regulating lipid droplet and mitochondrial interactions, while studies in gastric cancer have linked CPT1A-associated metabolic reprogramming to JAK/STAT3 signalling. Given that CPT1 inhibitors are already being tested for anti-cancer effects, the authors raise the provocative question of whether the efficacy of such strategies, and even of antiangiogenic therapies that induce fatty acid uptake through CD36, might differ between obese and normal-weight patients. If confirmed, the humble lipid droplet, long regarded as a passive fat reservoir, could emerge as both a biomarker and a therapeutic target in the fight against colorectal cancer.

Subject of Research: The role of exogenous fatty acid uptake, lipid droplet formation and PLIN2 expression in promoting the tumorigenic behaviour of colorectal cancer cells

Article Title: Lipid Accumulation Promotes Tumorigenic Behaviour of Colorectal Cancer Cells

Article References: Itzenhäuser, T., Schildt, F. S., Jochem, S., Sommer, J., Stürzl, M., Naschberger, E., Boßerhoff, A. K., & Hellerbrand, C. (2026). Lipid Accumulation Promotes Tumorigenic Behaviour of Colorectal Cancer Cells. Journal of Cellular and Molecular Medicine, 30(19), Article e71393. https://doi.org/10.1111/jcmm.71393

Image Credits: AI Generated

DOI: 10.1111/jcmm.71393

Keywords: colorectal cancer, lipid droplets, fatty acid uptake, obesity, PLIN2, CPT1A, oleic acid, lipid metabolism, beta-oxidation, tumour progression, EMT, interleukin-8

ADAM17, short for a disintegrin and metalloprotease 17, is also known as tumor necrosis factor-converting enzyme, or TACE. Its defining feature is its ability to shed membrane-bound proteins: it cleaves the extracellular portions of molecules anchored in the cell membrane, releasing them as soluble signaling factors. Among its best-known substrates are the precursors of epidermal growth factor receptor ligands, such as heparin-binding EGF-like growth factor, whose release activates EGFR signaling, a pathway central to cell proliferation and survival. ADAM17 also processes the interleukin-6 receptor, enabling IL-6 trans-signaling, a mechanism that amplifies inflammatory communication between cells. Through these activities, ADAM17 sits at the junction of inflammation and cancer biology, which is why it has been extensively studied in human breast cancer and other malignancies.

What has been missing, the researchers note, is any systematic characterization of ADAM17 signaling in veterinary pathophysiology. Canine mammary tumors share striking biological similarities with human breast cancer, including hormone dependence, histopathological diversity, and a propensity for metastatic spread, yet treatment options for affected dogs remain limited, often revolving around surgery and chemotherapy. The team, led by André Luz and Marina Badenes, with collaborators at NOVA University Lisbon and Lusófona University, set out to determine whether ADAM17 plays a functional role in these tumors and whether modulating the pathway could alter cancer-relevant behaviors.

The first question was clinical: is ADAM17 expressed differently in tumors compared with healthy tissue? The researchers compared ADAM17 mRNA levels in canine mammary carcinoma tissues against normal mammary gland samples. The result was clear. ADAM17 expression was significantly elevated in carcinomas of histopathological grade II or higher relative to normal controls. Because higher histopathological grade reflects greater cellular atypia and more aggressive biological behavior, the finding suggests that ADAM17 upregulation accompanies tumor progression. The authors further suggest that its expression may be associated with tumor progression and dissemination, although supplementary analyses across individual clinical and histopathological parameters, including breed, tumor multiplicity, nodal involvement, distant metastasis, tumor size, necrosis, ulceration, and mitotic activity, did not reveal statistically significant differences for those individual variables.

To probe function rather than mere correlation, the team turned to two established canine mammary tumor cell lines, FR37-CMT and FR10-CMT. Their strategy was pharmacological: stimulate the ADAM17 pathway, inhibit it, and observe what happens to key cancer-related processes. Stimulation was achieved with lipopolysaccharide, a bacterial endotoxin that provokes inflammatory signaling, and with phorbol-12-myristate-13-acetate, or PMA, a potent activator of protein kinase C that is known to trigger ADAM17 activation. Inhibition was pursued with several complementary agents, including batimastat (BB-94), a broad-spectrum metalloprotease inhibitor; GI254023X, which preferentially targets the related protease ADAM10; KP457 and MEDI3622, more selective ADAM17 inhibitors, the latter being an antibody-based inhibitor; and appropriate solvent controls.

The first biological outputs examined were cell viability, apoptosis, and the response to doxorubicin, a mainstay chemotherapeutic drug. Here the results were largely negative, and that in itself is informative. ADAM17 did not appear to play a major role in FR37-CMT cell viability or apoptosis under basal conditions, nor did modulating the pathway change the cytotoxic effectiveness of doxorubicin. In other words, ADAM17 does not seem to be a general survival factor for these tumor cells, and blocking it would not be expected to sensitize them to this particular chemotherapy agent. The team also examined epithelial-to-mesenchymal transition, the developmental program by which epithelial cancer cells acquire invasive, mesenchymal characteristics, and again found no major role for ADAM17 in the FR37-CMT model.

The decisive result came from a different assay: cell motility. Using scratch wound migration assays, in which a confluent cell monolayer is wounded and the rate at which cells close the gap is measured over time points of 4, 8, and 24 hours, the researchers found that activating the ADAM17 pathway enhanced the migration of both FR37-CMT and FR10-CMT cells. PMA stimulation accelerated the recovery of the scratch, and this effect could be blunted by ADAM17-targeted inhibitors. Conversely, inhibiting ADAM17 activity with BB-94, KP457, or MEDI3622 reduced the rate at which cells repopulated the wound, with the selective inhibitors providing mechanistic confirmation that the effect was attributable to ADAM17 rather than to off-target actions of the broader metalloprotease blockade. GI254023X, the ADAM10-preferring inhibitor, contributed additional context by implicating the closely related ADAM10 pathway in motility as well, suggesting a family-level contribution to cell movement in these tumors.

Why does motility matter? Metastasis, the process that makes cancer lethal, begins with local invasion: tumor cells must detach, migrate through surrounding tissue, enter blood or lymphatic vessels, and seed distant organs. A cell’s migratory capacity is therefore a direct functional readout of its metastatic potential. The finding that ADAM17 promotes migration, without appreciably affecting viability or chemotherapy response, refines the picture of what this enzyme does in canine mammary tumors. It is not a driver of tumor cell survival but a facilitator of movement, consistent with its known biology as a sheddase that releases factors enabling cells to remodel their surroundings and respond to motility cues. The supplementary data also showed that amphiregulin secretion by FR37-CMT cells was not increased by pathway activation, hinting that the motility effect may be mediated by other ADAM17 substrates or downstream pathways yet to be pinned down.

The translational implication is straightforward and, for veterinary oncology, potentially significant. If ADAM17 activity drives the migratory behavior of mammary tumor cells, then pharmacological inhibition of ADAM17 could represent a promising strategy to limit the metastatic spread of mammary cancer in dogs, as the authors conclude. This would position an ADAM17 inhibitor not as a cytotoxic drug that kills tumor cells, but as an anti-metastatic agent that restrains their ability to move and invade, an approach that could complement surgery and existing chemotherapy. The availability of selective inhibitors, including the antibody-based MEDI3622 tested in this study, provides a starting point for such a strategy, although the leap from cell culture dishes to canine patients will require further validation, including studies in primary tumor models and ultimately clinical trials.

The study also carries broader resonance beyond veterinary medicine. Because canine mammary tumors are widely regarded as a comparative model for human breast cancer, defining the role of ADAM17 in dogs may illuminate aspects of the enzyme’s behavior that are difficult to dissect in human clinical material. The work, conducted with samples collected in a clinical diagnostic context and approved by the local animal ethics committee, was supported by institutional and Portuguese national science funding, including the Foundation for Science and Technology. For now, the message is a measured one: a well-known human cancer protease has been shown to be upregulated in aggressive canine mammary carcinomas and to promote tumor cell motility, opening a concrete, testable avenue for keeping metastasis at bay in man’s best friend.

Subject of Research: The role of the ADAM17 protease pathway in canine mammary tumor cell migration and metastasis

Article Title: ADAM17 pathway promotes canine mammary tumor cell migration

Article References: Luz, A., Santos, J., Catarino, J., Sousa, C., Fonseca, J., Campos, S., Alves, M., Baptista, P. V., Faísca, P., Fernandes, A. R., & Badenes, M. (2026). ADAM17 pathway promotes canine mammary tumor cell migration. BMC Cancer. https://doi.org/10.1186/s12885-026-16984-2

Image Credits: AI Generated

DOI: 10.1186/s12885-026-16984-2

Keywords: ADAM17, canine mammary tumor, cell migration, metastasis, veterinary oncology, EGFR, IL-6 trans-signaling, metalloprotease inhibitors, EMT, doxorubicin, breast cancer, cell motility