CD44 is best known as a receptor for hyaluronan, a large sugar-rich molecule found in the extracellular matrix—the structural network that surrounds cells. When hyaluronan binds to CD44, it can activate intracellular signalling pathways that regulate proliferation, survival, migration and changes in cell identity. These signals may involve pathways such as PI3K–AKT, RAS–RAF–MEK–ERK, Wnt–β-catenin, NF-κB and YAP–TAZ. The result is a molecular system capable of translating physical and chemical changes in the tumour environment into instructions that help cancer cells adapt.

The receptor is also unusually complex because the CD44 gene can produce multiple protein forms through alternative splicing. The standard form, often called CD44s, is found in many normal tissues, while variant forms, known as CD44v, contain additional extracellular regions generated by the inclusion of variable exons. These variants can alter how the receptor interacts with growth factors, matrix components and signalling proteins. In several cancers, particular CD44 variants have been associated with aggressive disease, although their abundance and biological significance can differ between tumour types and even between regions of the same tumour.

One of the most closely studied functions of CD44 is its connection to cancer stem-like cells. These cells are not necessarily permanent or identical to stem cells in healthy tissue, but they can display enhanced abilities to self-renew, initiate new tumours and survive stress. CD44-positive populations have been reported in cancers including breast, colorectal, gastric, pancreatic, head and neck and liver malignancies. The review highlights that CD44 is not a universal or definitive cancer-stem-cell marker; instead, its importance depends on the tissue, the CD44 isoform, the surrounding microenvironment and the other markers present on the cell.

CD44 may also help cancer cells undergo epithelial–mesenchymal transition, or EMT, a developmental programme that can give stationary epithelial cells more mobile and invasive properties. During EMT-like changes, tumour cells may lose strong cell-to-cell adhesion and acquire the ability to move through tissue, enter blood vessels and establish distant colonies. CD44 signalling can interact with transcriptional regulators such as Snail, Slug, Twist and ZEB proteins, which are known to control EMT-associated gene expression. This interaction creates a potential molecular bridge between altered cell identity and metastatic behaviour.

The receptor’s effects extend beyond tumour cells themselves. CD44 is present on immune cells, fibroblasts and other stromal populations that occupy the tumour microenvironment. By influencing interactions among these cells, CD44 can contribute to a local environment that supports tumour growth. Its signalling has been linked to inflammatory responses, extracellular-matrix remodelling and the recruitment or functional alteration of immune populations. In some settings, these processes may reduce effective anti-tumour immunity, allowing malignant cells to persist despite the presence of immune surveillance.

Another concern is the relationship between CD44 and resistance to treatment. Cancer cells that express certain CD44 forms may be better equipped to withstand chemotherapy, radiation or targeted drugs through enhanced DNA-repair capacity, altered drug transport, antioxidant protection and survival signalling. CD44-positive cells can also occupy protected niches within tumours, where limited oxygen, nutrient changes and matrix interactions promote a more resilient state. These observations have made CD44 an attractive candidate for therapeutic intervention, but they also underline why simply eliminating CD44-bearing cells may not be sufficient.

Several strategies are being investigated to target the CD44 system. Antibodies and antibody–drug conjugates aim to recognise CD44 or selected CD44 variants and deliver toxic payloads directly to tumour cells. Hyaluronan-based nanoparticles and drug-delivery systems seek to exploit the receptor’s natural binding properties, potentially concentrating treatment in CD44-rich tumours. Other approaches attempt to block the interaction between CD44 and hyaluronan, inhibit downstream signalling, degrade hyaluronan in the tumour environment or target CD44-positive cancer stem-like populations. Each strategy faces technical barriers, including variable CD44 expression, the presence of the receptor in normal tissues and the difficulty of distinguishing malignant from healthy CD44-positive cells.

The review by Oh, Kim, Kim and colleagues presents CD44 as a promising but highly context-dependent therapeutic target. Its expression alone may not reliably predict prognosis or treatment response, because CD44 is shaped by alternative splicing, post-translational modification, cellular location and signals from the surrounding microenvironment. Future treatments may therefore need to combine CD44 targeting with immunotherapy, chemotherapy, radiation or inhibitors of specific signalling pathways. The broader message is that cancer biology cannot be reduced to a single marker: CD44 is better understood as a flexible molecular hub whose effects change with tumour type and disease stage. Mapping those differences could help researchers design more selective therapies while limiting damage to healthy tissues.

Subject of Research: CD44’s roles in cancer progression, metastasis, tumour microenvironment interactions, treatment resistance and targeted therapeutic strategies

Article Title: Multifaceted roles of CD44 in cancer progression and targeted therapeutic strategies

Article References: Oh, HJ., Kim, ST., Kim, HJ. et al. “Multifaceted roles of CD44 in cancer progression and targeted therapeutic strategies.” Experimental & Molecular Medicine (2026). https://doi.org/10.1038/s12276-026-01797-x

Image Credits: AI Generated

DOI: 10.1038/s12276-026-01797-x

Keywords: CD44, cancer progression, hyaluronan, cancer stem cells, metastasis, epithelial–mesenchymal transition, tumour microenvironment, drug resistance, targeted therapy, immunotherapy

Menin has long been a subject of intense scrutiny due to its diverse functions in various cancers such as leukemia, breast, prostate, and liver cancers. Despite extensive investigations, its implication in bladder cancer was previously obscure. The new study, conducted collaboratively by leading researchers across several prominent institutions including Harbin Medical University and Shanghai Jiaotong University School of Medicine, sheds light on this gap by demonstrating menin’s oncogenic properties in BLCA.

Initial analyses involving mRNA and protein expression profiles of bladder cancer patient tissues revealed that MEN1 is significantly upregulated in tumor samples compared to healthy controls. These elevated levels correlate closely with clinical parameters indicative of aggressive disease – notably advanced tumor stage, presence of lymph node metastasis, and increased patient age. Moreover, high MEN1 expression portends poor overall survival, underlining its clinical relevance as a potential prognostic biomarker.

Functional studies employing RNA interference to knock down MEN1 expression in bladder cancer cell lines yielded compelling evidence of menin’s role in tumorigenesis. MEN1 depletion led to marked inhibition of cell proliferation and induced a pronounced G1/S phase arrest in the cell cycle, signifying that menin facilitates cell cycle progression and cell division in BLCA cells. Supporting this, xenograft experiments in nude mice demonstrated a significant reduction in tumor volume upon MEN1 silencing, confirming menin’s tumor-promoting capacity in vivo.

To elucidate the molecular mechanisms underpinning menin’s oncogenic activity, the research team performed RNA sequencing coupled with KEGG pathway enrichment analysis. The results revealed that MEN1 knockdown induces profound alterations in gene expression across multiple biological pathways, including key regulators of the Wnt signaling cascade, autophagy, mitophagy, nucleotide excision repair, and apoptosis. These widespread transcriptional changes emphasize menin’s integral role in orchestrating diverse cellular processes central to cancer cell survival and proliferation.

Strikingly, the study found that menin modulates the Wnt/β-catenin signaling pathway, a canonical pathway often dysregulated in cancer. MEN1 knockdown significantly reduced β-catenin (encoded by CTNNB1) expression at both the mRNA and protein levels. Mechanistic assays revealed that menin directly binds to the proximal promoter region of CTNNB1, thereby activating its transcription and sustaining β-catenin signaling within BLCA cells. This novel insight into menin’s regulatory control over β-catenin highlights a critical axis driving bladder tumorigenesis.

Delving deeper, the researchers identified another transcription factor, TFAP2C, as a direct target of menin. Menin binds to the proximal promoter of TFAP2C in a manner mediated by the Mixed Lineage Leukemia (MLL) complex, leading to upregulation of TFAP2C expression. Intriguingly, subsequent experiments demonstrated that TFAP2C itself binds to the CTNNB1 promoter and is indispensable for the menin-dependent activation of the Wnt/β-catenin pathway. The data collectively articulate a sophisticated regulatory cascade whereby menin enhances TFAP2C expression, which in turn drives β-catenin transcription, reinforcing malignant cell proliferation.

This comprehensive characterization of the menin/TFAP2C/β-catenin signaling axis underscores a potential therapeutic vulnerability in bladder cancer. In light of this, the study evaluated BAY-15522, a small molecule inhibitor specifically targeting menin. Treatment with BAY-15522 effectively suppressed the proliferation of BLCA cells and curtailed tumor growth in preclinical models by disrupting the menin-mediated signaling network. These findings not only confirm menin’s oncogenic role but also position menin inhibitors as promising candidates for clinical intervention in BLCA management.

The implications of this research extend beyond bladder cancer, offering a conceptual framework for targeting menin and its downstream pathways in other malignancies where menin is aberrantly expressed. The ability of menin to regulate transcription factors and oncogenic signaling pathways highlights its multifunctional role as a master regulator of cancer cell biology. Therapeutically, targeting such central nodes could yield more durable and widespread anti-cancer effects.

Moreover, the observed positive correlation between MEN1 expression and tumor stage, patient age, and lymph node involvement suggests that menin could serve as a useful prognostic marker to stratify patient risk and personalize treatment approaches. Measuring MEN1 levels in clinical settings might help identify individuals who would benefit most from menin-targeted therapies, aligning with precision medicine goals.

This study also paves the way for future research to explore the broader interactome of menin in bladder cancer cells, investigating other potential co-factors and signaling pathways that may contribute to tumor progression and resistance mechanisms. The integration of epigenetic regulators, DNA repair machineries, and apoptosis pathways within menin’s influence opens many avenues for combinatorial therapeutic strategies.

In summary, this transformative research provides compelling evidence that menin acts as a critical oncogene in bladder cancer by orchestrating a regulatory axis involving TFAP2C and β-catenin, thus enhancing cell proliferation and tumor growth. Pharmacological inhibition of this axis impairs BLCA progression, spotlighting menin as an attractive molecular target for innovative therapeutics. As bladder cancer continues to pose clinical challenges worldwide, these insights offer renewed hope for developing more effective and targeted treatment modalities.

Subject of Research: The oncogenic role of menin (MEN1 gene product) in bladder cancer progression and its underlying molecular mechanisms.

Article Title: Menin facilitates the cell proliferation of bladder cancer via modulating the TFAP2C/β-catenin axis

Web References:

• GSEA software: https://www.gsea-msigdb.org/gsea/index.jsp
• Genes & Diseases Journal on ScienceDirect: https://www.sciencedirect.com/journal/genes-and-diseases
• DOI Link: http://dx.doi.org/10.1016/j.gendis.2025.101565

References:
Shi Q., Pan X., Zhang S., Wu M., Xu M., Li Y-Q., Zhong L., Wang Z-Q., Xu W., Luo Y. (2025). Menin facilitates the cell proliferation of bladder cancer via modulating the TFAP2C/β-catenin axis. Genes & Diseases. DOI: 10.1016/j.gendis.2025.101565.

Image Credits: Qing Shi, Xiang Pan, Shiheng Zhang, Mengyuan Wu, Meiqi Xu, Yun-Qi Li, Li Zhong, Zi-Qi Wang, Wanhai Xu, Yakun Luo

Keywords: Cell proliferation, Cancer, Bladder cancer, MEN1, Menin, TFAP2C, β-catenin, Wnt signaling, Cell cycle, RNA interference, Xenograft model, Molecular oncology

KRAS functions as a molecular switch within the RAS/MAPK and PI3K signaling pathways, pivotal for regulating cell growth, differentiation, and survival. Mutations at codon 12, particularly G12D, G12V, and G12R, induce constitutive activation of KRAS, locking it into a GTP-bound state that perpetuates aberrant downstream signaling. This sustained activation leads to uncontrolled cellular proliferation and drives the progression from early-stage pancreatic intraepithelial neoplasias to invasive carcinoma, eventually metastasizing to distant organs such as the liver. Given the profound role of KRAS mutations in PDAC biology, selectively targeting these variants has become a primary focus in cancer therapeutics.

Recent preclinical and clinical breakthroughs herald a new era in KRAS-targeted therapy. MRTX1133, a selective inhibitor designed to target KRAS^G12D, has demonstrated striking efficacy in preclinical models, achieving tumor shrinkage exceeding 85%. This represents a paradigm shift as MRTX1133’s molecular architecture exploits unique conformational features of the KRAS^G12D mutant, enabling high-affinity binding that disrupts its interaction with downstream effectors. Similarly, RMC-9805, another novel agent tailored for KRAS inhibition, has progressed into early-phase clinical trials with promising results, signaling feasibility in translating precision oncology approaches to PDAC patients.

Beyond mutation-specific inhibitors, innovative strategies such as proteolysis targeting chimeras (PROTACs), small interfering RNA (siRNA) delivery systems, and pan-KRAS inhibitors are under extensive investigation. PROTACs harness the cellular ubiquitin-proteasome system to induce targeted degradation of oncogenic KRAS proteins, potentially circumventing resistance mechanisms that arise with conventional inhibitors. Concurrently, siRNA-based therapies aim to silence KRAS expression at the mRNA level, presenting a complementary avenue to diminish oncogenic signaling. The development of pan-KRAS inhibitors seeks to simultaneously target multiple KRAS mutants, addressing the intratumoral heterogeneity observed in PDAC.

Despite these advancements, therapeutic resistance remains a formidable challenge. Tumors frequently adapt through compensatory activation of alternative pathways such as the MAPK and PI3K cascades or undergo phenotypic transitions like epithelial-to-mesenchymal transition (EMT), which enhances invasiveness and drug tolerance. This plasticity necessitates combination regimens that target multiple facets of tumor signaling and the tumor microenvironment. Promising approaches combine KRAS inhibitors with MEK, PI3K, or CDK4/6 inhibitors, aiming to obstruct escape routes leveraged by cancer cells.

Immunotherapeutic strategies are emerging as a vital component of these combination treatments, particularly given KRAS-driven PDAC’s characteristic immune suppression. Novel regimens pair KRAS inhibition with immune checkpoint blockade or therapies targeting immunosuppressive stromal elements, striving to rejuvenate anti-tumor immune responses. Early clinical findings suggest that integrating targeted agents with immunotherapy can elicit durable responses and overcome intrinsic resistance barriers.

The KRAS^G12C mutation, while less prevalent in PDAC compared to the G12D variant, has nonetheless provided critical insights into KRAS druggability. Agents such as adagrasib have exhibited meaningful clinical activity, with a reported 33% partial response rate in KRAS^G12C-mutant PDAC. These successes bolster optimism for mutation-specific interventions and underscore the necessity of comprehensive genomic profiling to stratify patients potentially benefiting from tailored therapies.

Metabolic rewiring is another hallmark of KRAS-mutant PDAC, driving adaptations like enhanced glycolysis and glutamine metabolism to sustain growth under nutrient-deprived conditions. Targeting these metabolic dependencies alongside KRAS signaling could serve as an additional therapeutic axis. Thorough understanding of metabolic vulnerabilities offers avenues to potentiate the efficacy of existing drugs and conceptualize novel agents disrupting tumor bioenergetics.

Crucially, the integration of next-generation sequencing and biomarker development facilitates precision medicine in PDAC. Identification of KRAS mutational status and concurrent genomic alterations enables personalized treatment planning, helping to optimize patient outcomes. The heterogeneity of PDAC demands such tailored approaches, as uniform therapies have consistently failed to yield significant survival benefits.

A recent comprehensive review authored by a collaborative team from Xinjiang Medical University and Shenzhen University, published in Cancer Biology & Medicine on July 7, 2025, synthesizes the state of the art in KRAS-directed therapies for PDAC. The article meticulously details the evolution of drug development targeting KRAS, mechanisms of acquired resistance, and the rationale for combinational therapeutic strategies. This scholarly work articulates a hopeful narrative that overturns the longstanding dogma of KRAS being an insurmountable target.

Dr. Wenting Zhou, corresponding author of the review, emphasizes the convergence of multiple treatment modalities as a critical milestone. “The fusion of mutation-specific inhibitors, immune modulation, and metabolic interventions provides a holistic assault on KRAS-driven PDAC,” she notes. Such a multi-dimensional strategy aims not merely to extend survival but to redefine the therapeutic landscape for a cancer type notoriously resistant to treatment.

These advances are poised to transform the clinical management of PDAC, offering new avenues for patients with advanced and inoperable disease stages. As these therapies continue to evolve through rigorous clinical validation, they hold promise not only to improve survival outcomes but also to enhance quality of life. Moreover, lessons learned from PDAC may illuminate pathways for targeting KRAS-dependent mechanisms across other malignancies, broadening the impact of this research.

In conclusion, the once “undruggable” KRAS oncoprotein is rapidly becoming an achievable target through a spectrum of innovative biochemical and immunological approaches. Continued efforts to decode the complex biology underlying KRAS mutations, coupled with translational advances in targeted drug development, underscore an exciting frontier in pancreatic cancer therapeutics. This momentum fuels hope in the battle against one of the deadliest human cancers, heralding a new epoch in precision oncology.

Subject of Research: Not applicable

Article Title: Drugging the ‘undruggable’ KRAS: breakthroughs, challenges, and opportunities in pancreatic cancer

News Publication Date: 7-Jul-2025

References:
10.20892/j.issn.2095-3941.2025.0122

Image Credits: Cancer Biology & Medicine

Keywords: Pancreatic cancer

This pioneering investigation focused on the AGS cell line, a model for human gastric adenocarcinoma, notorious for its recalcitrance against paclitaxel after prolonged exposure. By integrating carvedilol into the treatment protocol, the research team observed a significant reversal of drug resistance. The mechanistic underpinnings uncovered reveal carvedilol’s multifaceted interaction with key molecular signaling pathways that govern cellular survival and apoptosis, addressing a critical hurdle in chemotherapy resistance.

One of the most striking revelations of this study concerns carvedilol’s modulation of apoptotic regulators. Apoptosis, or programmed cell death, is essential for eliminating cancerous cells, and its dysregulation often contributes to chemoresistance. The research demonstrated that carvedilol influences an array of apoptotic proteins, tipping the balance toward cell death in otherwise resistant cancer cells. This reactivation of the apoptotic machinery is central to restoring sensitivity to paclitaxel, reflecting carvedilol’s potential to enhance chemotherapeutic efficacy.

Beyond apoptosis, the study delved into carvedilol’s effect on the Notch signaling pathway, a critical regulator of cell fate decisions and tumor progression. Aberrant Notch signaling has been implicated in the maintenance of cancer stem cells and resistance to chemotherapy. Interestingly, carvedilol treatment downregulated components of the Notch pathway in paclitaxel-resistant AGS cells, thereby attenuating their survival advantage. This finding highlights that carvedilol’s anticancer properties extend beyond its classical beta-adrenergic receptor antagonism.

The investigative team also uncovered notable interactions with the PI3K/AKT pathway, a major intracellular signaling cascade that mediates growth, proliferation, and survival in cancer cells. Hyperactivation of PI3K/AKT contributes heavily to chemotherapy resistance by promoting cell survival and inhibiting apoptosis. Carvedilol’s ability to attenuate PI3K/AKT signaling disrupts this survival network, facilitating increased apoptotic sensitivity to paclitaxel. This dual modulation of apoptotic and survival pathways underscores the comprehensive impact carvedilol exerts on resistant cancer cells.

In parallel, alterations in the ERK1/2 signaling pathway were observed following carvedilol administration. ERK1/2, a component of the MAPK signaling family, is instrumental in cell growth and differentiation processes. Its dysregulation frequently correlates with tumor cell proliferation and resistance to anticancer drugs. The research revealed that carvedilol effectively downregulated ERK1/2 activity, aligning with decreased cellular proliferation and heightened susceptibility to paclitaxel-induced cytotoxicity.

Remarkably, this scientific effort also explored the regulatory role of miR-34a, a microRNA recognized for its tumor suppressor functions. MicroRNAs like miR-34a orchestrate gene expression post-transcriptionally and are critical modulators of cancer biology. The study found that carvedilol upregulated miR-34a expression in resistant gastric cancer cells, contributing to the suppression of oncogenic pathways and reinforcing the induction of apoptosis. This epigenetic influence broadens our understanding of how non-anticancer drugs can be repurposed for cancer therapy through subtle genomic regulation.

The translational implications of these integrated signaling modulations are profound. By employing carvedilol, an existing and well-characterized safe therapeutic agent, to overcome paclitaxel resistance, this approach offers a tangible pathway to augment standard chemotherapeutic protocols without necessitating entirely new drug development. This strategy could rapidly progress into clinical trials, leveraging carvedilol’s established pharmacological profile to expedite repositioning efforts in oncology.

Furthermore, the convergence of carvedilol’s effects on multiple pathways typical to cancer resilience underscores the importance of multi-targeted interventions. Single-pathway targeting often elicits compensatory survival mechanisms in tumor cells, but the broad-spectrum disruption documented here advocates for a paradigm shift toward combinatorial approaches that comprehensively disable cancer cell defenses. This insight may inform future drug design and combination therapy strategies.

From a molecular biology standpoint, the elucidation of carvedilol’s interaction with signaling networks demands deeper exploration. Understanding whether carvedilol exerts these effects through direct engagement with receptor targets or indirect modulation via cellular stress responses remains a tantalizing question. The complexity of intracellular cross-talk suggests potential for synergistic targeting that could refine dose regimens and minimize adverse effects.

This study also invites broader consideration of cardiovascular drugs as reservoirs of anticancer potential. The repurposing of beta-blockers, traditionally assigned to manage hypertension and heart failure, signals a promising niche in oncology pharmacotherapy. The pleiotropic effects observed open avenues for systematic screening of approved drugs for off-target benefits, significantly shortening the bench-to-bedside journey.

Challenges remain, of course, including verifying carvedilol’s effectiveness across diverse gastric cancer subtypes and patient-derived xenografts, as well as assessing its impact in vivo amidst the intricacies of tumor microenvironments. Clinical trials will need to carefully balance carvedilol’s pharmacodynamics with chemotherapy schedules to maximize synergistic cytotoxicity while safeguarding patient safety.

Nevertheless, the findings herald a new frontier in cancer treatment where old drugs gain novel roles, informed by cutting-edge molecular insights. Personalized medicine stands to benefit uniquely, with carvedilol potentially becoming part of tailored regimens for patients exhibiting paclitaxel resistance signatures detected via biomarkers like miR-34a expression or pathway activity profiles.

As our comprehension of cancer signaling pathways deepens and computational biology advances, mapping precise drug-pathway interactions will become increasingly sophisticated. This study exemplifies such progress, marrying molecular biology and pharmacology to unlock unforeseen therapeutic opportunities. The convergence of carvedilol’s cardiological origins with oncologic efficacy underscores the serendipitous potential embedded within existing pharmacopoeias.

Overall, this research not only enhances our armamentarium against gastric cancer but also invigorates research enthusiasm for drug repurposing strategies. It demonstrates that overcoming chemoresistance is achievable through molecularly informed, strategic pharmacological interventions that repurpose familiar molecules for novel clinical frontiers.

In conclusion, the discovery that carvedilol sensitizes paclitaxel-resistant gastric cancer cells via modulating apoptotic regulators, Notch, PI3K/AKT, ERK1/2 signaling pathways, and miR-34a expression invites a fresh perspective on cancer treatment. This integrative approach to overcoming resistance mechanisms not only offers practical therapeutic promise but also enriches the scientific dialogue on multi-target pharmacology and drug repurposing. As this research progresses toward clinical application, it holds the potential to significantly improve survival and quality of life for patients grappling with chemoresistant gastric cancer.

Subject of Research: The effect of carvedilol on paclitaxel-resistant gastric cancer AGS cells focusing on apoptotic regulators, Notch, PI3K/AKT, ERK1/2 signaling pathways, and miR-34a expression.

Article Title: Carvedilol sensitizes paclitaxel-resistant gastric cancer AGS cells to paclitaxel: influences on apoptotic regulators, Notch, PI3K/AKT, ERK1/2 signaling pathways, and miR-34a expression.

Article References:
Niapour, A., Hosseinzadeh, S., Mohebi, Y. et al. Carvedilol sensitizes paclitaxel-resistant gastric cancer AGS cells to paclitaxel: influences on apoptotic regulators, Notch, PI3K/AKT, ERK1/2 signaling pathways, and miR-34a expression. Med Oncol 42, 392 (2025). https://doi.org/10.1007/s12032-025-02966-0

Image Credits: AI Generated