Cancer cells may be able to reprogram more than gene activity and signaling networks. A study led by researchers at Fudan University and Zhongshan Hospital in Shanghai reports that oncogenic RAS signaling can also alter how ribosomes interpret individual codons during protein synthesis. The findings, published in Vita, describe a codon-specific translation program that helps RAS-driven tumors produce proteins needed for rapid growth, survival, and resistance to treatment. Rather than simply increasing or decreasing the activity of selected genes, the pathway appears to influence how efficiently the instructions within messenger RNA are converted into proteins. This adds a new layer to the biology of cancer and suggests that the translation machinery itself may become a therapeutic target in tumors driven by RAS mutations.
RAS is one of the most frequently altered cancer-driving systems in human disease. When activated by mutation or persistent upstream signaling, RAS stimulates the MAPK pathway and other downstream networks that promote cell division, metabolism, survival, and adaptation. These signals are traditionally understood as molecular switches that ultimately change transcription, the process by which DNA instructions are copied into messenger RNA. The new research indicates that this explanation is incomplete. Even after messenger RNA has been produced, RAS may continue shaping the final protein output by controlling the speed and efficiency with which ribosomes read the genetic code. This distinction is important because two cells with similar levels of a messenger RNA may still produce different amounts of its encoded protein if their translation efficiency differs.
The genetic code is composed of three-letter units called codons, each of which specifies an amino acid or a stop signal. Although several different codons can encode the same amino acid, synonymous codons are not always functionally equivalent. Their abundance, the availability of matching transfer RNAs, and the behavior of translation factors can influence how quickly a ribosome moves along an RNA molecule. One codon that can slow translation is CGA, which encodes arginine. When a ribosome reaches a CGA site, the corresponding transfer RNA may be delivered less efficiently than the molecules required for more frequently decoded codons. This can create a temporary pause, or bottleneck, during protein production. Such pauses can affect the folding, quantity, and timing of newly synthesized proteins, making codon composition an important but often overlooked source of biological regulation.
The researchers investigated whether cancer-associated pathways could manipulate these codon-dependent barriers. They compared cells with activated RAS with models involving MYC overexpression or loss of the tumor suppressor PTEN. Their experiments revealed that the effect was not a general increase in translation and did not produce the same codon pattern across all oncogenic conditions. RAS activation was particularly associated with more efficient decoding of CGA-containing messenger RNAs. Genes enriched in CGA codons include regulators involved in ribosome production, RNA processing, and cell-cycle control. By easing the translation bottleneck in these transcripts, RAS signaling could increase the supply of proteins that support proliferation and cellular stress tolerance. The comparison with MYC and PTEN also suggested that different cancer-driving events may establish distinct translational programs rather than relying on one universal mechanism.
The study identified a molecular connection between RAS signaling and CGA decoding through METTL13, an enzyme known as a methyltransferase. Methyltransferases transfer methyl groups to specific molecular targets, and METTL13 modifies eEF1A, a translation elongation factor that helps deliver aminoacyl-tRNAs to the ribosome. When RAS is active, the downstream kinase RSK phosphorylates METTL13 at a specific regulatory site. This phosphorylation increases METTL13 activity, leading to enhanced dimethylation of eEF1A at lysine 55. The modified elongation factor appears to improve the delivery of the transfer RNA needed to decode CGA. In practical terms, the RAS–RSK–METTL13–eEF1A axis helps ribosomes move through CGA sites more efficiently, reducing the pause that would otherwise limit production of CGA-enriched proteins.
This mechanism illustrates how signaling pathways can reach directly into the machinery of protein synthesis. RAS does not need to change every gene in a cancer cell to reshape its behavior. By improving the translation of a selected group of messenger RNAs, it may selectively expand the production of proteins that are especially useful to a growing tumor. The result is a form of post-transcriptional regulation: control that occurs after DNA has been transcribed into RNA but before the RNA has been converted into a functional protein. Because codon composition differs from gene to gene, this process can create a selective effect even when many transcripts are present at similar levels. The researchers describe this phenomenon as a “codon-defined translational program,” emphasizing that the sequence of an RNA can influence how oncogenic signaling determines protein output.
The team also examined whether this pathway contributes to treatment resistance. RAS-pathway inhibitors can initially reduce tumor growth, but cancer cells that tolerate treatment may survive and eventually restore disease progression. In patient-derived tumor organoids and other cancer models, drug-tolerant cells retained strong activity in the METTL13–eEF1A pathway and continued to decode CGA-containing transcripts efficiently. When METTL13 was blocked, the resistant cells showed impaired survival and responded more strongly to inhibitors targeting RAS signaling. These results suggest that resistance may depend not only on genetic changes or alternative signaling routes, but also on a translational adaptation that allows cells to maintain production of essential proteins under drug pressure. The findings do not yet establish a clinical treatment, but they identify a potential weakness that could be exploited in combination therapies.
Targeting METTL13 could offer a different strategy from broadly suppressing protein synthesis. General translation inhibitors can damage healthy tissues because normal cells also depend on continuous protein production. A codon-selective dependency, if sufficiently restricted to RAS-driven tumors, might provide a more focused therapeutic window. However, important questions remain before the approach can be tested widely in patients. Researchers will need to develop selective and pharmacologically practical METTL13 inhibitors, determine how much the pathway varies among tumor types, and identify biomarkers that reveal which cancers depend most strongly on CGA decoding. The safety consequences of disrupting eEF1A modification will also require careful evaluation, since the factor participates in translation throughout the body. The organoid and cancer-model results provide a rationale for further investigation, but they should not be interpreted as evidence that an approved treatment is already available.
The work broadens the concept of how cancer rewires cell biology. Tumors are commonly described as diseases of mutated genes, altered signaling, and abnormal transcription. This study adds the ribosome and the genetic code’s usage patterns to that picture. Codons may act not merely as interchangeable symbols but as regulatory features that determine how cellular conditions influence protein production. In RAS-driven cancer, a signaling cascade can modify a translation factor and remove a hidden obstacle in the decoding of a specific codon. That connection may help explain how tumors rapidly adapt to environmental stress and targeted drugs. It also raises the possibility that other oncogenic pathways regulate other codons or translation factors in similarly selective ways. By linking RAS activity to codon-specific translation, the researchers reveal an additional layer of tumor biology—one that could inspire new diagnostic tools and precision therapies aimed at the way cancer cells read, rather than simply transcribe, their genetic instructions.
Subject of Research: Not applicable
Article Title: A codon-defined translational program promotes RAS-driven cancer progression and drug resistance
Web References: https://doi.org/10.15302/vita.2026.07.0049
References: Vita. “A codon-defined translational program promotes RAS-driven cancer progression and drug resistance.” DOI: 10.15302/vita.2026.07.0049
Image Credits: Higher Education Press
Keywords: RAS signaling, cancer biology, codon-specific translation, CGA codon, METTL13, eEF1A, protein synthesis, drug resistance, MAPK pathway, precision oncology
Tags: cancer cell translation regulationcodon-specific translation in cancerdownstream effects of RAS activation on translationimpact of RAS on genetic code interpretationmolecular mechanisms of RAS in cancer developmentnew cancer treatment strategies targeting ribosomesprotein synthesis alteration in RAS-driven tumorsRAS mutations and gene expressionRAS signaling and ribosome reprogrammingribosomal decoding and cancer progressiontherapeutic targeting of translation machinerytumor growth and protein production mechanisms
