The biological premise underlying the study rests on a rapidly expanding field known as epitranscriptomics, the study of reversible chemical tags placed on RNA molecules after they are transcribed from DNA. The most famous of these tags, N6-methyladenosine or m6A, is deposited by writer enzymes, removed by erasers, and interpreted by reader proteins, collectively forming a regulatory layer that controls RNA stability, splicing, export, and translation. The researchers in this study did not limit themselves to m6A; they also included regulators of N1-methyladenosine (m1A), 5-methylcytosine (m5C), and 7-methylguanosine (m7G), assembling a comprehensive panel of 84 such regulators. Each of these modification types has been implicated individually in tumor initiation, progression, and immune evasion, but the authors argue that studying them in isolation misses the coordinated dysregulation that likely drives malignant behavior in melanoma.

To build their model, the team performed unsupervised clustering on the expression patterns of all 84 regulators across multiple melanoma cohorts, drawing heavily on data from The Cancer Genome Atlas (TCGA). This analysis revealed three distinct RNA modification subtypes of melanoma, and the clinical stakes of this molecular stratification became immediately apparent: survival differed significantly among the three groups, demonstrating that the collective activity of RNA modification machinery carries genuine prognostic information rather than mere molecular noise. Because clustering alone does not identify which individual genes matter most, the researchers next turned to weighted gene co-expression network analysis, or WGCNA, a technique that organizes thousands of genes into modules based on correlated expression patterns and then links those modules to clinical traits of interest. This step pinpointed one module, designated ME13, as most significantly associated with the RNA modification subtypes, providing a focused set of candidate genes for predictive modeling.

The core of the study is the construction of the RMODscore itself. Using least absolute shrinkage and selection operator regression, known as LASSO, together with multivariate Cox proportional hazards regression, the team compressed the candidate gene list into a ten-gene signature. LASSO regression is particularly well suited to this kind of problem because it penalizes model complexity, effectively shrinking the coefficients of less informative genes to zero and guarding against the overfitting that plagues many high-dimensional genomic studies. Multivariate Cox regression then ensured that each retained gene contributed independent prognostic information, adjusting for the influence of the others. The resulting score assigns each melanoma patient a continuous risk value computed from the weighted expression levels of the ten genes, with higher scores indicating a molecular profile associated with worse outcomes.

Validation was where the model earned its credibility. The RMODscore showed strong predictive performance not only in the TCGA discovery cohort but also, critically, in four independent melanoma immunotherapy datasets drawn from patients treated with checkpoint blockade. Across these cohorts, patients with high RMODscore values experienced significantly poorer survival than those with low scores, and the high-score group was consistently associated with clinical resistance to immunotherapy. The model’s ability to generalize across cohorts generated by different institutions and treatment protocols is an important benchmark, as many published genomic signatures fail precisely this test of external validation.

Mechanistically, the researchers found that the score divided melanoma tumors into biologically recognizable states. Tumors with high RMODscore values exhibited what oncologists describe as immune-cold phenotypes: they carried fewer infiltrating immune cells, showed dampened expression of immune activation signatures, and displayed upregulation of proliferation-related pathways that drive unchecked cell division. These are exactly the tumors that tend to shrug off checkpoint inhibitors, which work by unleashing pre-existing antitumor T cells and therefore require an inflamed tumor microenvironment to function. Conversely, tumors with low RMODscore values showed greater immune activation, the inflamed, T cell–rich milieu in which antibodies targeting PD-1 and CTLA-4 achieve their most durable responses. In other words, the RNA modification signature appears to capture, at the level of transcript regulation, the immunological architecture of the tumor that ultimately determines whether immunotherapy can succeed.

Beyond prognosis and immunotherapy prediction, the study ventured into the territory of drug repurposing. By correlating RMODscore values with pharmacogenomic data, the team found that the score predicted sensitivity to inhibitors of the ERK and JNK signaling pathways, both components of the mitogen-activated protein kinase cascade that is famously hyperactivated in melanoma through BRAF and NRAS mutations. ERK inhibitors are currently in clinical development as a strategy to overcome resistance to BRAF-targeted therapy, and JNK inhibitors have been explored in various oncology contexts. The suggestion that a high RMODscore might flag tumors susceptible to these drugs raises the possibility of using the score not merely as a passive prognostic marker but as an active guide to combination or sequenced treatment strategies, pairing immunotherapy with pathway inhibition in patients whose scores indicate a poor likelihood of checkpoint response.

The clinical significance of the work lies partly in what it adds to an increasingly crowded field of prognostic signatures for melanoma. Numerous gene expression models have been proposed over the past decade, including signatures based on immune genes, metabolic pathways, and broader multi-omics integrations, and several have advanced toward clinical use in assessing recurrence risk. What distinguishes the RMODscore approach is its grounding in RNA modification biology, a mechanistic layer that sits upstream of both tumor-intrinsic proliferation programs and tumor-immune crosstalk. Because RNA modification regulators are enzymes and binding proteins with defined activities, they represent not just biomarkers but potential therapeutic targets in their own right; dysregulated m6A machinery, for example, has already been shown in preclinical studies to influence PD-L1 expression and T cell-mediated killing. A score derived from this machinery could therefore track biology that is itself druggable.

The authors are appropriately measured in their conclusions, framing the RMODscore as a tool for prognostic stratification that may provide preliminary insights for future therapeutic exploration rather than a ready-made clinical test. Significant hurdles remain before such a signature could reach the clinic. The study relies on retrospective bulk transcriptomic data, which cannot resolve how RNA modification regulators behave in individual cell types within the tumor microenvironment; single-cell and spatial profiling would be needed to confirm the cellular origins of the signal. Prospective validation in randomized immunotherapy trials, standardization of the measurement assay, and demonstration that the score improves clinical decisions beyond established factors such as tumor stage, lactate dehydrogenase levels, and PD-L1 immunohistochemistry would all be required. Nevertheless, the consistency of the score across five independent cohorts and its dual performance in both survival prediction and immunotherapy response forecasting give it a stronger evidentiary footing than many signatures of its kind.

The research was funded by the Henan Province Natural Science Foundation Key Science Fund Project and the Central Plains Science and Technology Innovation Leadership Talent Program, and the corresponding author is Zhen Li of the Interventional Radiology Department at the First Affiliated Hospital of Zhengzhou University. Published as an open-access article under a Creative Commons license, the study arrives at a moment when the epitranscriptomics of cancer is moving from descriptive cataloging toward predictive, clinically actionable science. If subsequent studies confirm its performance, the RMODscore could join a growing arsenal of molecular tests that help clinicians decide which melanoma patients should receive immunotherapy first-line, which might benefit from earlier combination strategies, and which experimental agents targeting the RNA modification machinery itself deserve accelerated development.

Traditionally, cancer has been viewed primarily through the lens of genomic mutations—faulty DNA instructions that lead to unchecked cellular proliferation. However, mounting evidence suggests that this genomic narrative is incomplete without considering epitranscriptomics—the chemical modification of RNA molecules that regulate gene expression post-transcriptionally. RNA modifications, especially methylation on tRNAs and ribosomal RNAs, play a pivotal role in fine-tuning protein synthesis. Disruptions in these modifications may reprogram cancer cells’ protein production machinery, enabling malignancy and therapeutic resistance.

The helm of this pioneering endeavor is Professor James Williamson, the Cecil H. and Ida M. Green Chair of Chemistry at Scripps Research. Collaborating with him are esteemed scientists Gary Siuzdak, also from Scripps, specializing in metabolomics, and Rachel Green, a Bloomberg Distinguished Professor at Johns Hopkins University School of Medicine. Over the course of the next five years, their integrated approach will scrutinize the dynamic landscape of RNA modifications in the context of cancer and nutrient availability, with funding nearing $5 million contingent on ongoing approvals.

Central to their focus is the phenomenon of methylation influenced by methionine, an essential amino acid found abundantly in protein-rich diets. Methionine serves as the primary methyl donor in various cellular processes, including the methylation of RNA molecules. Both ribosomes and transfer RNAs, critical players in protein synthesis, bear numerous methyl groups that shape their function. The availability of methionine thus critically regulates these epitranscriptomic marks, with direct implications for how cancer cells modulate their proteome in response to environmental cues.

Recent studies have underscored the potential of dietary methionine restriction as a strategy to curb cancer growth, yet the molecular underpinnings of this phenomenon remain poorly defined. This research aims to bridge that gap by dissecting how methionine scarcity remodels the chemical landscape of RNA within cancer cells. Using advanced mass spectrometry, Williamson’s laboratory will precisely map alterations in methylation and other modifications on ribosomal RNAs and tRNAs, providing a molecular atlas of response to nutrient stress.

Complementing this, Siuzdak’s metabolomics expertise will illuminate shifts in the intracellular availability of methionine and related metabolites, revealing how fluctuations in nutrient pools interface with epitranscriptomic remodeling. This integrative analysis promises unprecedented insights into the metabolic-epitranscriptomic crosstalk that governs cancer cell survival and proliferation under nutrient-limiting conditions.

To translate these molecular alterations into functional outcomes, Rachel Green’s team will employ ribosome profiling, an innovative method that captures snapshots of active translation across the cancer cell genome. By quantifying which mRNAs are preferentially translated and which are downregulated in response to altered RNA modifications, the researchers can connect molecular changes directly to shifts in protein synthesis—a critical determinant of cancer cell behavior.

Such mechanistic clarity is vital, as it could unveil novel therapeutic targets aimed at disrupting cancer’s adaptive translational program. Understanding how methionine-driven methylation patterns sculpt the proteomic landscape offers a tangible entry point for interventions. It could also rationalize and refine dietary methionine restriction protocols, enhancing their efficacy and applicability across diverse cancer types.

Beyond methylation, this initiative is poised to pioneer a broader exploration of RNA modifications—chemical tags that extend well beyond methyl groups and whose roles in oncogenesis remain largely uncharted. By establishing robust frameworks and methodological paradigms, the project sets a foundation for future studies to chart the complex epitranscriptomic networks in cancer.

The implications of this research extend beyond cancer, as RNA modifications have emerged as fundamental regulators of cellular physiology in health and disease. The ability to dynamically modulate protein synthesis through chemical tags on RNA offers a versatile regulatory layer with far-reaching biological significance.

This pioneering work is a testament to the power of interdisciplinary collaboration, blending chemistry, metabolomics, and molecular biology to tackle the intricate metabolic and molecular labyrinth of cancer. By focusing on the metabolic basis of epitranscriptomic changes, the researchers cast light on the profound ways in which nutrient signals influence cancer progression.

As cancer therapeutics evolve towards precision medicine, understanding the nuanced interplay between metabolism and gene expression at the RNA level will be crucial. This research paves the way for innovative therapeutic strategies that exploit cancer cells’ metabolic vulnerabilities, potentially leading to treatments with higher specificity and fewer side effects.

Funded under award number 1U01CA305256-01, this RNAMoDO program project reflects the cutting edge of cancer research, promising to illuminate the RNA modifications that drive oncogenesis and to open new avenues for intervention.

Through this comprehensive and multifaceted investigation, Scripps Research, alongside Johns Hopkins University, is set to redefine our grasp of cancer biology—shifting from a purely genetic perspective to one that embraces the dynamic and complex chemical alphabet written on RNA.

Subject of Research:
RNA modifications influencing cancer cell growth and methionine-dependent methylation processes

Article Title:
Scripps Research Leads Transformative Study on RNA Modifications and Nutrient-Driven Cancer Growth

News Publication Date:
Information not provided

Web References:
https://www.scripps.edu/faculty/williamson/
https://www.scripps.edu/faculty/siuzdak/
https://reporter.nih.gov/search/7T3nB_MDg0O7_j1rVJ3SXA/project-details/11226464

Image Credits:
Credit: Scripps Research

Keywords:
Cancer, RNA modifications, methylation, methionine restriction, ribosome profiling, metabolomics, translational control, epitranscriptomics, Scripps Research, National Cancer Institute, RNAMoDO program

Central to this discovery is the identification of the RNA methyltransferase TRMT10C as a key mediator of tumor growth in HCC. This enzyme catalyzes methylation modifications on specific RNA molecules, influencing gene expression patterns vital for cancer cell function. The investigative team demonstrated that disulfiram acts as a copper ionophore, facilitating the intracellular influx of copper ions, which in turn downregulates TRMT10C expression. The suppression of TRMT10C induces a cascade of epitranscriptomic changes, notably diminishing methylation on the messenger RNA (mRNA) of the transcription factor c-FOS. This decrease in methylation stabilizes and increases the expression of c-FOS, a crucial regulatory protein with tumor-suppressor properties in this context.

Elevated levels of c-FOS execute a multi-pronged inhibitory effect on the cancer cell microenvironment. It directly represses the expression of PCSK9, a protein intricately involved in lipid metabolism that frequently becomes aberrantly activated in HCC, contributing to excessive lipid droplet accumulation within tumor cells. This accumulation fosters an environment conducive to rapid cancer cell proliferation and survival. Concurrently, c-FOS impedes CD146, a cell adhesion molecule known for its pivotal role in promoting angiogenesis—the formation of new blood vessels—which tumors require for nutrient supply and metastasis.

The functional consequences of modulating this TRMT10C–c-FOS axis were rigorously validated through a series of in vitro and in vivo experiments. Cultured HCC cell lines treated with disulfiram showed marked reductions in lipid droplets and angiogenic markers, while mouse models exhibited significantly slower tumor growth and diminished vascular structures within tumors. Notably, when disulfiram was combined with thalidomide, an established anti-angiogenic agent, these effects were potentiated, providing evidence for possible synergistic therapeutic regimens targeting multiple facets of tumor biology.

Corroborating the translational relevance of these findings, the research team analyzed clinical data sets from HCC patients. This analysis revealed a stark correlation between patient survival outcomes and the expression profiles of the pathway components. High levels of TRMT10C and PCSK9 were statistically linked to a poor prognosis, reinforcing their oncogenic roles. Conversely, patients exhibiting elevated c-FOS expression experienced comparatively prolonged survival, underscoring the potential prognostic and therapeutic value of modulating this pathway.

From a mechanistic viewpoint, the study highlights a novel epigenetic regulation mode within cancer biology through RNA methylation alterations. RNA methyltransferases like TRMT10C are emerging as critical players in orchestrating gene expression beyond the DNA code, influencing mRNA stability, translation efficiency, and protein synthesis. Disulfiram’s ability to target this enzyme and thereby reprogram the epitranscriptome provides an innovative paradigm for repurposing established drugs with known safety profiles while enhancing therapeutic options for difficult-to-treat malignancies such as HCC.

Beyond its molecular insights, this research underscores the broader clinical imperative of addressing metabolic reprogramming and angiogenesis in cancer treatment. Lipid metabolism abnormalities not only confer growth advantages to tumors but also create metabolic vulnerabilities that can be exploited pharmacologically. Meanwhile, angiogenesis remains a proven therapeutic target, and combining agents that interfere with angiogenic signaling with metabolic disruptors, as demonstrated here, may yield substantial synergistic benefits.

The implications of employing disulfiram in HCC are profound. Traditionally utilized to discourage alcohol consumption by inducing unpleasant physiological responses to ethanol, disulfiram’s repositioning as an anti-cancer agent reflects an exciting trend in oncology: drug repurposing. This approach expedites the translation of existing medications with known pharmacokinetics and toxicity profiles into new therapeutic contexts, reducing development times and costs—a critical advantage in the ongoing battle against cancer.

In summary, the multifaceted investigation elucidated how disulfiram orchestrates the downregulation of TRMT10C, leading to enhanced c-FOS activity that suppresses PCSK9-mediated lipid metabolism and CD146-driven angiogenesis, thereby stymying HCC progression. Such discoveries not only illuminate the intricate biological underpinnings of liver cancer but also furnish a viable therapeutic strategy leveraging RNA epigenetics and metabolic intervention. Moving forward, clinical trials will be essential to evaluate disulfiram’s efficacy and safety as a frontline or adjuvant therapy in HCC patients.

The study, published in the reputable journal Science China Life Sciences, marks a significant milestone in oncology research by integrating molecular biology, cancer metabolism, and epigenetics. It exemplifies how detailed mechanistic studies can unveil drug targets and inform precision medicine strategies aimed at improving outcomes for patients afflicted with aggressive malignancies.

Researchers and clinicians alike should note the potential for combinatory regimens involving disulfiram and anti-angiogenic drugs such as thalidomide to maximize anti-tumor efficacy. Moreover, the identification of biomarkers such as TRMT10C, PCSK9, and c-FOS paves the way for more personalized treatment protocols, wherein patient stratification based on molecular signatures could optimize therapeutic responses.

The findings attest to the transformative power of epitranscriptomic modifications in cancer pathogenesis and treatment, encouraging further exploration of RNA-modifying enzymes as drug targets. These insights also spotlight copper ionophores as a class of compounds capable of modulating cancer-related signaling pathways, warranting deeper pharmacological investigations.

By unveiling a previously uncharted molecular pathway linking disulfiram to tumor suppression in liver cancer, this research not only expands the scientific understanding of HCC biology but also catalyzes hope for more effective, accessible, and targeted therapies in the near future.

Subject of Research: Liver cancer (hepatocellular carcinoma), RNA epigenetics, lipid metabolism, angiogenesis, drug repurposing
Article Title: Disulfiram combats hepatocellular carcinoma by modulating TRMT10C-mediated RNA methylation, enhancing c-FOS expression, and suppressing PCSK9 and CD146 to inhibit tumor growth and angiogenesis
News Publication Date: 2024
Web References: http://dx.doi.org/10.1007/s11427-024-2968-1
Image Credits: ©Science China Press
Keywords: hepatocellular carcinoma, disulfiram, TRMT10C, c-FOS, PCSK9, CD146, RNA methylation, lipid metabolism, angiogenesis, anti-cancer therapy, copper ionophore, drug repurposing

Oral squamous cell carcinoma remains a significant clinical challenge, with late diagnosis and rapid metastasis contributing to its high mortality rate worldwide. The research team focused on METTL3, a primary m6A RNA methyltransferase responsible for installing N6-methyladenosine marks on RNA transcripts. These epigenetic modifications are well documented to impact RNA stability, splicing, translation efficiency, and degradation, thereby controlling gene expression post-transcriptionally. Intriguingly, elevated METTL3 activity has been reported across various cancers, yet its precise role in OSCC was hitherto unclear.

The study reveals that in OSCC cells, METTL3 is markedly upregulated, leading to globally increased m6A methylation levels. This epitranscriptomic surge promotes the enhanced processing of the primary microRNA precursor pri-miR-146a into its mature form, miR-146a-5p. miRNAs like miR-146a-5p play pivotal roles in gene silencing by binding to complementary sequences in target messenger RNAs (mRNAs), resulting in their degradation or translational repression. Here, the mature miR-146a-5p directly targets SMAD4, a well-known tumor suppressor gene critical for cellular growth regulation and apoptotic pathways.

SMAD4 functions as a central mediator within the transforming growth factor-beta (TGF-β) signaling cascade, which coordinates cellular proliferation, differentiation, and programmed cell death—processes frequently dysregulated in cancers. The downregulation of SMAD4 by miR-146a-5p, as orchestrated by METTL3-mediated m6A modifications, dismantles this tumor-suppressing pathway. Consequently, OSCC cells exhibit increased proliferation, enhanced colony formation, greater migratory and invasive capacities, alongside reduced apoptosis. This comprehensive disruption not only facilitates tumor growth but also contributes to metastasis and treatment resistance observed clinically.

Experimental manipulations further substantiated this molecular interplay. Silencing METTL3 or pharmacologically inhibiting its methyltransferase activity led to a significant decrease in miR-146a-5p levels while restoring SMAD4 expression in OSCC cell lines. These changes culminated in attenuated malignant behaviors, including slower cell division rates and heightened sensitivity to apoptotic stimuli. Conversely, reintroducing miR-146a-5p or knocking down SMAD4 reversed these effects, confirming the essential role of the METTL3-miR-146a-5p-SMAD4 axis in disease progression.

These insights carry profound therapeutic implications. Targeting this newly identified molecular cascade might revolutionize OSCC management by curbing the cancer’s aggressive features. Notably, STM2457, a small-molecule inhibitor of METTL3 previously investigated in other malignancies such as acute myeloid leukemia, exhibited promising anti-tumor activity in vitro by impairing METTL3 function. Leveraging METTL3 inhibitors, alongside strategies to block miR-146a-5p or restore SMAD4, could potentially suppress OSCC growth and dissemination more effectively than existing treatments.

Moreover, the elucidation of this epigenetic regulatory mechanism enriches our understanding of RNA modifications in cancer biology. The m6A RNA methylation landscape, shaped by enzymes like METTL3, has emerged as a crucial layer of gene control that cancer cells exploit for survival and expansion. This study highlights the need to explore RNA methylomics further, underscoring how intricate post-transcriptional modifications can drive tumorigenesis through microRNA-mediated pathways.

The discovery also sheds light on why OSCC remains recalcitrant to conventional therapies. By illuminating a cancer-promoting axis that suppresses intrinsic tumor-suppressive machinery, this research suggests that future therapeutic development should integrate epigenetic and RNA-based approaches in addition to traditional chemotherapy and radiation. Such integrated efforts could improve patient outcomes by sensitizing tumors to therapy and preventing relapse.

From a clinical diagnostics perspective, the elevated expression of METTL3 and miR-146a-5p alongside reduced SMAD4 may serve as valuable biomarkers for OSCC prognosis, detection, and treatment stratification. Non-invasive assays to monitor these molecules could enhance early diagnosis when interventions are most effective, thereby reducing OSCC-related mortality.

In summary, the investigation by Jayaprakash, Karemore, and Khandelia introduces the METTL3/miR-146a-5p/SMAD4 axis as a critical regulatory pathway underpinning OSCC progression. Through the aberrant upregulation of RNA methylation and subsequent microRNA dysregulation, this axis disrupts tumor-suppressive controls to favor aggressive cancer phenotypes. Targeting components of this axis holds significant promise for developing innovative and precise treatments for a disease that continues to impose a substantial global health burden.

As RNA epigenetics gains momentum in cancer research, this study exemplifies the therapeutic potential of modulating RNA modifiers like METTL3. The interplay between epitranscriptomic modifications, microRNAs, and tumor suppressors expands the landscape of actionable molecular targets. Continued exploration in this realm is poised to transform how clinicians understand, diagnose, and treat oral squamous cell carcinoma, heralding a new era in cancer therapeutics grounded in RNA biology.

Subject of Research: Cells

Article Title: METTL3 promotes oral squamous cell carcinoma by regulating miR-146a-5p/SMAD4 axis

News Publication Date: 8-May-2025

Web References:
http://dx.doi.org/10.18632/oncotarget.28717

Image Credits:
Copyright: © 2025 Jayaprakash et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0).

Keywords: cancer, oral cancer, m6A RNA methylation, METTL3, miR-146a-5p, SMAD4