In a groundbreaking collaborative effort, researchers from the MRC Laboratory of Medical Sciences (LMS) and Imperial College London have unearthed a critical vulnerability within the cellular machinery of RAS-driven cancers—one that holds the promise of transforming therapeutic approaches for some of the most aggressive and treatment-resistant tumours. This discovery centers on the spliceosome, an essential cellular complex responsible for refining RNA transcripts before they translate into functional proteins, a process now revealed as a druggable dependency in RAS-positive senescent cancer cells.
RAS genes are ubiquitous drivers of oncogenesis, found mutated in roughly one-third of all human cancers, including notoriously difficult-to-treat malignancies such as pancreatic, colorectal, and liver cancers. These oncogenes encode molecular switches that regulate cell proliferation; when mutated, they perpetually drive cells toward uncontrolled growth, often culminating in aggressive tumours that defy conventional therapeutics. Although recent advances have yielded drugs targeting some specific RAS mutations, these therapies are limited in scope and efficacy, and resistance mechanisms frequently emerge, highlighting the need for alternative strategies.
The research team investigated the remarkably intensified biochemical demands placed on cancer cells harboring RAS mutations, particularly focusing on the RNA splicing process mediated by the spliceosome. RNA splicing serves as a vital editing step by excising non-coding introns and optimizing messages for protein synthesis. However, in RAS-driven cells, this system becomes overwhelmed due to the accelerated cellular proliferation and increased production of RNA transcripts. By analyzing this critical bottleneck, the researchers have identified that the elevated activity of specific spliceosome components, known as splicing factors, creates an exploitable weakness within RAS-positive cells.
Delving deeper, the team concentrated on oncogene-induced senescence, a state induced by RAS mutations in which cells exit the cell cycle but secrete inflammatory factors damaging the surrounding tissue environment. These senescent cells, marked by their sustained harmful signaling rather than proliferation, contribute to cancer progression and tissue dysfunction. The LMS Senescence Research Group pinpointed two key splicing factors, SF3B1 and RBM39, which are notably upregulated in these senescent RAS-mutant cells. Intriguingly, these factors are targetable by existing pharmacological inhibitors, making them prime candidates for therapeutic intervention.
When these splicing factors were pharmacologically inhibited, the results were striking: RAS-mutant senescent cells were selectively eliminated, and this vulnerability extended beyond senescent populations to various RAS-driven cancer models. These included pre-cancerous lesions and fully developed tumours in the liver, colon, and pancreas. Such findings reveal that the deregulated spliceosome machinery acts as an Achilles’ heel for RAS-mutant cancers, opening a novel and previously unrecognized avenue for combating malignancies long deemed incurable.
Crucially, the research underscores that targeting the RNA splicing machinery with inhibitors against SF3B1 and RBM39 not only halts tumour growth but also reduces tumour size in mouse models. This dual effect hints at a therapeutic potential encompassing both cancer prevention by eliminating premalignant cell clusters and cancer treatment by curbing progression in established malignancies. These promising outcomes spotlight the spliceosome as more than a passive actor in cancer biology but rather a strategic fulcrum with clinical utility.
The significance of this work resonates beyond RAS-driven cancers. Spliceosome deregulation and heightened splicing factor expression have been documented in various tumour types, indicating that spliceosome dependencies might represent a broader hallmark of oncogenic stress adaptation. Nevertheless, the researchers highlight that RAS-mutant cells are uniquely reliant on this system due to their intense metabolic and proliferative demands, making splicing inhibition especially effective in these contexts.
Professor Jesús Gil, senior author and head of the Senescence group at LMS, emphasizes the translational potential of the findings, stating that while the team specializes in fundamental biology rather than drug development, the pre-existence of inhibitors for the identified splicing factors paves the way for collaborations aimed at clinical applications. This foundation could accelerate the repurposing of known drugs into new anti-cancer regimens focused on the spliceosome, circumventing the prolonged timelines typically necessary for novel drug discovery.
In addition to providing a new therapeutic target, the research enriches the understanding of tumour biology by illuminating how cancer cells’ intrinsic stress responses, such as senescence and splicing overload, can be co-opted into treatment strategies. By exploiting the cellular coping mechanisms themselves, researchers offer a paradigm shift from targeting cancer cells solely on their proliferative capacity to dismantling their essential housekeeping operations responsible for RNA processing and protein synthesis.
The study represents an international scientific collaboration inclusive of the LMS, Imperial College London, the University of Lisbon, and University Hospital Tübingen, embodying the collective efforts needed to tackle complex oncogenic processes. Supported by the Medical Research Council and Cancer Research UK, this research propels a promising frontier in molecular oncology where mastery over fundamental RNA biology intersects with clinical oncology.
While further studies are necessary to elaborate upon dosing regimens and potential combinatory therapies, the identification of the spliceosome as a druggable dependency underscores an exciting frontier. It invites additional exploration into the interplay between senescence, RNA splicing, and oncogenic signaling, fostering hope for improved therapeutic outcomes against cancers fueled by RAS mutations, and potentially others that share similar molecular vulnerabilities.
Ultimately, these findings challenge the status quo of cancer therapy by positing that undermining the RNA processing machinery could serve as a lethal blow to tumour cells, striking at the heart of their metabolic and proliferative demands. This innovative approach may soon offer patients diagnosed with historically intractable RAS-driven cancers a novel lifeline, transforming one of oncology’s most formidable challenges into a treatable condition.
Subject of Research: Cellular machinery vulnerabilities in RAS-driven cancers and targeting spliceosome components.
Article Title: Spliceosome induction is a druggable dependency of RAS-driven senescence and cancer.
News Publication Date: 15-Apr-2026.
Web References: http://dx.doi.org/10.1038/s41467-026-71564-z
Image Credits: Laura Bousset, MRC Laboratory of Medical Sciences.
Keywords: RAS oncogenes, spliceosome, cellular senescence, splicing factors, SF3B1, RBM39, cancer therapeutics, RNA processing, tumour vulnerability, senescence-induced cancer, molecular oncology.
