Colorectal cancer remains a formidable challenge in oncology, largely because of its high rate of relapse despite advances in surgery, chemotherapy, and targeted therapies. At the heart of this resilience are cancer stem cells (CSCs)—a subpopulation within tumors adept at evading treatment and regenerating tumors through self-renewal and differentiation. Understanding the molecular mechanisms that regulate these stem-like properties is critical for developing therapies that not only shrink tumors but prevent recurrence. Recent work from a team led by researchers at The Second Affiliated Hospital, Zhejiang University School of Medicine, sheds new light on this issue by elucidating the role of the BEX2 protein in suppressing colorectal cancer stemness via the MCL1-Hedgehog signaling axis.
The study, published in Cancer Biology & Medicine in early 2026, reveals that BEX2 functions as a potent antagonist of colorectal cancer stemness. BEX2 levels inversely correlate with hallmark traits of cancer stem cells, including tumor-initiating capacity, chemoresistance, and invasive potential. This discovery adds a critical piece to the puzzle of tumor heterogeneity and treatment failure by pinpointing a molecular brake that restrains the most resilient tumor cells. The authors present a compelling model in which BEX2 destabilizes MCL1, a mitochondrial anti-apoptotic protein, thereby attenuating Hedgehog signaling—a key pathway governing stemness and therapy resistance in various cancers.
Analyses of public genomic datasets such as TCGA and GEO provided initial clues, as these databases showed reduced BEX2 expression in colorectal cancer tissues compared to normal colon tissue. Furthermore, diminished BEX2 expression statistically correlated with poorer disease-free survival, suggesting clinical relevance. Expression of established stemness markers, including CD133 and CD44, were elevated in samples with low BEX2, indicating a functional link between BEX2 status and tumor cell stem-like characteristics. This computational groundwork laid the foundation for subsequent in vitro and in vivo experimental validation.
In cultured colorectal cancer cell lines, genetic ablation of BEX2 led to increased formation of spheroids—three-dimensional cellular aggregates that serve as functional surrogates for stemness. These BEX2 knockout cells also harbored an expanded population expressing the CSC marker CD133, alongside upregulation of pluripotency factors NANOG and OCT4. Such molecular hallmarks are widely accepted signatures of stem cell identity, reinforcing BEX2’s role as a suppressor of stem-like traits. Conversely, enforced overexpression of BEX2 reversed these phenotypes, diminishing sphere formation and CSC marker expression, underscoring the protein’s functional importance.
Beyond stemness markers, BEX2 loss profoundly impacted cellular behaviors linked to cancer aggressiveness. BEX2-deficient cells demonstrated enhanced migratory and invasive capabilities in vitro assays, hallmarks associated with metastatic potential and poor prognosis. Intriguingly, these cells also exhibited increased resistance to oxaliplatin, a frontline chemotherapeutic agent for colorectal cancer, providing a plausible mechanistic explanation for clinical chemoresistance and relapse. In vivo, xenograft mouse models injected with BEX2-depleted cells showed substantially higher tumor burden and growth rates, further validating the tumor suppressive effects of BEX2.
Mechanistic interrogation revealed that BEX2 physically interacts with MCL1, promoting its ubiquitination and subsequent proteasomal degradation. MCL1 is a member of the BCL-2 family of proteins known for their roles in apoptosis inhibition and survival signaling. By destabilizing MCL1, BEX2 effectively weakens downstream Hedgehog pathway activity. Hedgehog signaling has been implicated extensively in the maintenance of CSC properties across multiple malignancies, including colorectal cancer. Loss of BEX2 consequently stabilizes MCL1, enhancing Hedgehog signaling and fueling stemness, chemoresistance, and invasiveness.
To further confirm this mechanistic axis, the research team employed pharmacological inhibitors targeting MCL1 and components of the Hedgehog pathway. In BEX2-deficient cells, these inhibitors mitigated the enhanced stemness and drug resistance phenotypes, demonstrating that the BEX2-MCL1-Hedgehog axis is both necessary and sufficient for regulating CSC traits. This pivotal finding opens avenues for combinatorial therapeutic strategies that might restore BEX2 function or directly disrupt MCL1/Hedgehog signaling to eradicate CSCs and improve patient outcomes.
This research carries profound translational implications. If further clinical studies validate BEX2 as a biomarker associated with CSC abundance and recurrence risk, it could inform patient stratification and personalized treatment plans. Therapeutic approaches aiming to augment BEX2 function or mimic its destabilization of MCL1 may heighten tumor susceptibility to conventional drugs and reduce relapse rates. Targeting stem cell-specific pathways is an emerging frontier in cancer therapy, and this study provides a valuable mechanistic roadmap in colorectal cancer.
By elucidating how BEX2 serves as a molecular brake on colorectal cancer stem cells, the study reframes our understanding of tumor dynamics. Instead of focusing solely on tumor bulk reduction, effective therapies must also disable the subpopulation of cells that orchestrate tumor regeneration and drug resistance. This research team deftly connects the dots from cellular biology through molecular biochemistry to clinical relevance, offering a model that integrates tumor suppression, stemness regulation, and therapeutic resistance under a unified signaling axis.
Moreover, this study highlights the importance of post-translational regulation in cancer biology. The ubiquitination and degradation of MCL1 by BEX2 exemplify how controlling protein stability can decisively influence complex cellular behaviors like stemness and resistance. Such insights could inspire broader investigations into similar regulatory networks across other cancers, potentially revealing conserved mechanisms exploitable for drug development.
The findings also emphasize the value of leveraging large-scale clinical genomic datasets in cancer research. Using TCGA and GEO enabled the identification of clinically meaningful expression patterns and survival correlations, aligning experimental results with patient outcomes. This integrative approach strengthens the impact and applicability of research discoveries, bridging lab bench to bedside.
In summary, this groundbreaking study redefines the role of BEX2 in colorectal cancer by positioning it as a key modulator of stemness through the MCL1-Hedgehog signaling axis. Its ability to suppress cancer stem cell traits, curb invasiveness, and enhance drug sensitivity provides a promising molecular target in the ongoing battle against colorectal cancer relapse. Future efforts to translate these findings into clinical practice could mark a turning point in overcoming tumor recurrence and improving long-term survival for patients afflicted by this disease.
Subject of Research: Not applicable
Article Title: BEX2 influences the MCL1-Hedgehog signaling axis to regulate the potential of stemness characterization in colorectal cancer
News Publication Date: 5-Jan-2026
References: DOI 10.20892/j.issn.2095-3941.2025.0120
Image Credits: Cancer Biology & Medicine
Keywords: Cancer stem cells, colorectal cancer, BEX2, MCL1, Hedgehog signaling, chemoresistance, tumor relapse, ubiquitination, stemness regulators, CD133, NANOG, OCT4
