The platform relies on patient-derived organoids, three-dimensional clusters of tumor cells grown in a supportive gel that recapitulate key architectural and molecular features of the original cancer. Organoids have generated enormous enthusiasm in precision oncology because they allow clinicians to screen multiple drugs against a living surrogate of a patient’s tumor before committing that patient to a regimen. Yet the conventional route to building them, which begins with surgically resected or biopsied tissue, carries substantial drawbacks. Tissue acquisition is invasive, often requires a procedure that may not be clinically justified, and yields samples with low tumor cellularity. The resulting cultures can be contaminated with stromal and immune cells that dilute the tumor-specific signal, and establishment rates for pancreatic cancer organoids have historically been frustratingly low.

The Yonsei University team, led by researchers from the Division of Gastroenterology in collaboration with the Departments of Pathology and Hepatobiliary and Pancreatic Surgery at Severance Hospital, took a different route entirely. Rather than solid tissue, they started with malignant effusions, the pleural fluid that accumulates around the lungs and the ascitic fluid that pools in the abdomen of patients with advanced pancreatic ductal adenocarcinoma. These fluids are collected routinely for symptom management through minimally invasive drainage procedures, meaning that the raw material for organoid culture is essentially a clinical byproduct. Because the fluid already contains free-floating tumor cells shed from metastatic deposits, the researchers reasoned that it could serve as a rich, relatively pure starting inoculum.

Their reasoning proved correct. Fluid-derived organoids, or FDOs, established from these effusions grew faster than organoids generated from matched tissue samples, showed a higher establishment success rate, and carried markedly less non-tumor contamination. The comparison was not simply a matter of convenience. The team performed extensive quality control to demonstrate that FDOs faithfully mirror the biology of the parental tumors. Histopathological examination of hematoxylin and eosin stained sections showed that the organoids retained the glandular architecture characteristic of pancreatic ductal adenocarcinoma. Immunostaining for cytokeratin 7, an epithelial marker expressed in pancreatic ductal cells, confirmed ductal origin. Critically, mutation analysis confirmed that the organoids carried the same KRAS driver mutations as the original tumors. Since activating mutations in KRAS, most commonly at codon 12, occur in the vast majority of pancreatic cancers and anchor much of the field’s targeted drug development, this genetic concordance is essential for the model to have any translational value.

To characterize organoid morphology and drug response in fine detail without destructive processing, the researchers turned to holotomography, a label-free imaging technique that uses coherent light to reconstruct three-dimensional refractive index maps of living cells. This allowed quantitative measurement of cellular and organoid morphology and of how the structures changed in response to drug exposure, complementing conventional viability assays.

One of the most clinically significant demonstrations involved MRTX1133, a selective inhibitor of the KRAS G12D mutant protein. KRAS G12D is among the most common KRAS variants in pancreatic cancer, and MRTX1133 has emerged as a preclinical benchmark for direct KRAS targeting in this tumor type. In the study, FDOs harboring the KRAS G12D mutation showed marked sensitivity to the inhibitor, confirming that the fluid-derived platform can reproduce the drug-response behavior expected of a genetically defined tumor. The result establishes a proof of concept that FDOs can serve as a rapid and scalable test bed for emerging targeted agents, potentially shortening the path from genetic diagnosis to an individualized treatment decision.

The second major contribution of the study goes beyond the platform itself and into the molecular roots of chemotherapy failure. Gemcitabine, a nucleoside analog that has anchored pancreatic cancer chemotherapy for years, frequently stops working as tumors evolve resistance. To understand why, the team performed transcriptomic profiling, comparing gene expression in FDOs that responded to chemotherapy with expression in those that did not. Gene set enrichment and differential expression analysis converged on three genes that were consistently upregulated in the resistant cultures: CEMIP, which encodes cell migration inducing hyaluronidase 1; CALB2, which encodes calbindin 2, also known as the heart and neural crest derivatives expressed protein; and LY6D, a member of the lymphocyte antigen 6 family of glycosylphosphatidylinositol-anchored cell surface proteins.

Expression alone does not prove causation, so the researchers moved to functional validation. When they manipulated the activity of these genes in pancreatic cancer cell lines, the results were unambiguous: elevated CEMIP, CALB2, and LY6D suppressed apoptosis, the programmed cell death pathway that gemcitabine is designed to trigger, and thereby conferred resistance to the drug. CEMIP in particular has been previously implicated in hyaluronic acid metabolism and epithelial-mesenchymal transition, processes that pancreatic tumors exploit to remodel their microenvironment and escape cytotoxic stress. The new findings place all three genes squarely in the mechanistic chain linking cellular stress to survival.

The clinical implications of the three-gene signature were reinforced by outcome data. In analyses of patient cohorts, high expression of the CEMIP, CALB2, and LY6D signature correlated with worse progression-free survival and worse overall survival, indicating that the same genes that protect organoids from gemcitabine in a dish are associated with poorer outcomes in patients. This dual role, as both a mechanistic driver and a prognostic marker, is what gives the finding its translational weight. A test measuring the three-gene signature could in principle identify patients unlikely to benefit from standard chemotherapy, steering them toward alternative regimens or clinical trials of targeted and resistance-overcoming strategies. The genes themselves also represent candidate therapeutic targets, since interfering with their activity might restore sensitivity to apoptosis-inducing drugs.

The work also carries broader implications for how organoid models are built across oncology. Effusions are not unique to pancreatic cancer; malignant pleural and peritoneal effusions arise in ovarian, gastric, lung, and breast cancers, among others. A methodology that converts a routine drainage procedure into a high-fidelity drug-screening platform within days rather than weeks could be adapted widely, particularly for patients with advanced disease for whom tissue biopsy is impractical or unsafe. The scalability of the approach addresses one of the persistent bottlenecks of precision oncology: the sheer logistics of generating a personalized model quickly enough for it to influence a treatment decision made under time pressure.

The study was conducted under ethical approval from the Institutional Review Board of Yonsei University with written informed consent from all patients, and it was supported by grants from the National Research Foundation of Korea and the Korea Health Technology R&D Project through the Korea Health Industry Development Institute. The research article was published as an accepted, citable open-access version carrying a permanent digital object identifier, with the final version of record to follow.

Taken together, the findings advance pancreatic cancer research on two fronts simultaneously. They provide a minimally invasive, rapid, and genetically faithful organoid platform derived from malignant effusions, validated against a state-of-the-art KRAS targeted inhibitor. And they expose a concrete molecular mechanism of chemotherapy resistance, distilled into a three-gene signature with demonstrated prognostic power. For a disease in which treatment options remain scarce and clinical timelines are unforgiving, tools that accelerate both drug selection and biomarker discovery are welcome indeed. The next steps, which the researchers and the field more broadly will be watching closely, involve prospective validation of the gene signature in larger patient cohorts and exploration of whether targeting CEMIP, CALB2, or LY6D can resensitize resistant tumors to gemcitabine and other cytotoxic agents.

The findings place p38β at the center of a biological switch that allows liver cancer cells to preserve stem-like properties while avoiding a cellular alarm system known as the unfolded protein response, or UPR. Cancer cells often manufacture unusually large amounts of proteins, remodel their metabolism and endure oxygen deprivation, creating intense stress inside the endoplasmic reticulum, the cellular compartment responsible for folding and processing newly made proteins. Under normal circumstances, this stress activates the UPR, which either restores protein-folding capacity or, if damage is too severe, triggers programmed cell death.

BiP, also known as HSPA5 or GRP78, is one of the UPR’s key regulators. It acts as a molecular chaperone, helping proteins fold correctly and monitoring stress-sensing pathways embedded in the endoplasmic-reticulum membrane. When unfolded proteins accumulate, BiP changes its interactions with these sensors, including PERK, IRE1 and ATF6, initiating a coordinated response. This response can temporarily protect a cell, but persistent or excessive UPR activation may become lethal. The new research indicates that p38β-mediated phosphorylation changes BiP’s behavior in a way that dampens this protective checkpoint.

Phosphorylation is a reversible chemical modification in which a phosphate group is attached to a protein, often altering its shape, stability, location or interactions with other molecules. Protein kinases such as p38β perform this modification in response to intracellular signals, including inflammation, oxidative stress and other forms of environmental pressure. According to the study, p38β targets BiP and thereby suppresses UPR activation in hepatocellular carcinoma cells. Rather than allowing endoplasmic-reticulum stress to escalate toward cell death, the modified BiP appears to help malignant cells maintain a state of controlled adaptation.

That adaptation may be particularly important for cancer stemness. Cancer stem-like cells are not necessarily identical to normal tissue stem cells, but they share properties such as self-renewal, developmental flexibility and the ability to generate diverse tumor-cell populations. In liver cancer, these cells are widely considered a major source of tumor initiation, recurrence and treatment resistance. By sustaining stemness-associated programs, the p38β–BiP pathway could help a small fraction of tumor cells survive therapy and later repopulate the tumor.

The mechanism also offers an explanation for chemoresistance. Many anticancer drugs damage DNA, disrupt replication or intensify metabolic and protein-folding stress. A cancer cell that can suppress the UPR’s lethal consequences may tolerate these pressures more effectively than a less adaptable cell. The study’s central conclusion is that p38β-dependent BiP phosphorylation provides hepatocellular carcinoma with precisely this advantage, allowing tumor cells to withstand treatment while preserving the biological traits linked to relapse.

The work is significant because it connects three processes that are often studied separately: stress signaling, cancer-cell plasticity and drug resistance. p38 kinases have long been associated with inflammatory and stress responses, while BiP has been examined as a marker and regulator of endoplasmic-reticulum stress. Linking a specific kinase-driven modification of BiP to stemness and chemotherapy resistance suggests that the interaction is not merely a consequence of tumor stress, but may actively organize the cancer cell’s survival strategy.

The findings also point toward a potential therapeutic vulnerability. In principle, blocking p38β activity, preventing BiP phosphorylation or restoring an appropriate UPR response could make tumor cells less able to tolerate chemotherapy. Such strategies would require careful development, however. The p38 family participates in normal immune, inflammatory and tissue-repair processes, while BiP is essential for healthy cells that experience physiological protein-folding demands. A treatment that interferes with this pathway would need to distinguish malignant stress adaptation from normal cellular maintenance.

Future studies will be needed to determine how broadly the mechanism operates across patient tumors, whether BiP phosphorylation can be measured reliably as a biomarker and which treatment combinations are most effective. It will also be important to establish whether p38β inhibition can selectively eliminate stem-like cancer cells without causing unacceptable toxicity. Nevertheless, the study offers a compelling molecular explanation for why some liver tumors remain stubbornly resistant: they may be using a kinase-controlled modification of a central stress chaperone to keep their internal alarm system quiet while preserving the capacity to survive, renew and return.

Subject of Research: p38β-mediated BiP phosphorylation, unfolded protein response suppression, stemness and chemoresistance in hepatocellular carcinoma

Article Title: p38β-mediated BiP phosphorylation drives stemness and chemoresistance by suppressing UPR activation in hepatocellular carcinoma

Article References: Xu, L., Huang, I.B., Zhang, M. et al. p38β-mediated BiP phosphorylation drives stemness and chemoresistance by suppressing UPR activation in hepatocellular carcinoma. Nat Commun (2026). https://doi.org/10.1038/s41467-026-76073-7

Image Credits: AI Generated

DOI: 10.1038/s41467-026-76073-7

Keywords: hepatocellular carcinoma, liver cancer, p38β, BiP, HSPA5, GRP78, phosphorylation, unfolded protein response, endoplasmic reticulum stress, cancer stemness, chemoresistance, cancer biology

The role of ULK1 in cancer biology has garnered attention due to its involvement in autophagy and cellular stress responses. Autophagy, a cellular degradation process that recycles damaged organelles and proteins, can be a double-edged sword in cancer therapy. While it can promote cell survival under stress, it can also facilitate cancer cell death when appropriately targeted. In the context of oxaliplatin treatment, the interplay between ULK1-mediated autophagy and apoptosis is particularly relevant, as enhanced autophagic activity could provide a survival advantage for cancer cells exposed to chemotherapy.

In the study published in the British Journal of Cancer, Rong and colleagues investigate how ULK1 contributes to oxaliplatin resistance in colon cancer. They reveal that ULK1 exerts its influence through the phosphorylation of Bax on serine 184 (S184), a post-translational modification that alters the pro-apoptotic function of this key player in the apoptotic cascade. Bax is crucial in mediating mitochondrial outer membrane permeabilization, a step necessary for initiating apoptosis. The modification of Bax by ULK1 thus plays a critical role in determining the fate of colon cancer cells in the presence of chemotherapy.

Understanding this phosphorylation event is vital as it highlights a potential target for overcoming resistance to oxaliplatin. By inhibiting ULK1 or preventing the phosphorylation of Bax at S184, researchers may find a way to restore sensitivity to oxaliplatin, enhancing its efficacy in otherwise resistant cancer cell populations. This kind of targeted approach exemplifies the shift toward precision medicine, where therapy is tailored based on the molecular characteristics of an individual’s tumor.

The findings from this study suggest that the relationship between ULK1 and Bax may extend beyond a simple regulatory mechanism; it indicates a sophisticated network of signaling pathways that dictate cellular responses to stress. This complexity of interactions underscores the necessity of delving deeper into the cellular context surrounding ULK1 activity, particularly how various oncogenic signals and tumor microenvironment factors interact with this kinase.

The potential for ULK1 as a therapeutic target invites further exploration into small molecules or biological agents that could selectively inhibit its activity. The development of such agents must be pursued with caution, given the duality of autophagy as both a protector and a killer in cancer biology. Future research will need to characterize the specific cellular contexts in which ULK1 inhibition leads to therapeutic benefit, ensuring that these strategies do not inadvertently promote tumor survival.

In addition to the focus on ULK1, the study emphasizes the need for comprehensive profiling of other pathways that may interact with Bax phosphorylation. Investigating co-factors and downstream effectors in the ULK1 signaling cascade could reveal further vulnerabilities in colon cancer cells. This line of inquiry supports a broader understanding of how alterations in one signaling pathway might reverberate through the intricate web of cancer cell signaling—ultimately shaping therapeutic responses.

Moreover, the implications of ULK1’s role extend beyond colon cancer to other malignancies that show a similar pattern of chemoresistance. Researchers should assess whether the ULK1-Bax axis operates in other cancer types treated with platinum-based therapies or even in different classes of chemotherapy agents. This cross-cancer examination could illuminate universal mechanisms of resistance and highlight shared therapeutic targets.

As the oncology field continues to grapple with the phenomenon of drug resistance, identifying and characterizing factors like ULK1 will be paramount. The integrative approach that combines foundational research with clinical insights could pave the way for innovative therapeutic strategies. Practitioners will eventually rely on molecular stratification of cancers to predict responses to treatment and tailor therapies accordingly.

While the findings of this study offer hope, the road to implementing ULK1-targeted therapies in clinical settings will require rigorous preclinical and clinical validation. The reproducibility of these results across diverse patient cohorts provides a key focus for future investigations. As these efforts unfold, the scientific community remains vigilant, committed to elucidating the underlying biology of chemoresistance and translating these insights into tangible clinical benefits.

In summary, the intricate relationship between ULK1 and Bax underscores a critical pathway that drives oxaliplatin resistance in colon cancer, presenting novel avenues for therapeutic intervention. Continued exploration into ULK1’s role, along with broader investigations into how similar mechanisms operate across various cancers, will grant significant insights into overcoming one of oncology’s most persistent challenges.

Subject of Research: Oxaliplatin resistance in colon cancer and the role of ULK1 and Bax phosphorylation.

Article Title: ULK1 promotes oxaliplatin resistance of colon cancer via phosphorylation of Bax S184.

Article References:

Rong, Z., Xing, J., Wu, L. et al. ULK1 promotes oxaliplatin resistance of colon cancer via phosphorylation of Bax S184.
Br J Cancer (2026). https://doi.org/10.1038/s41416-025-03223-x

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41416-025-03223-x

Keywords: Oxaliplatin resistance, Colon cancer, ULK1, Bax phosphorylation, Chemotherapy, Molecular targets.