FAM86A methylation of eEF2 links mRNA translation elongation to tumorigenesis.

eEF2 post-translational modifications (PTMs) can profoundly affect mRNA translation dynamics. However, the physiologic function of eEF2K525 trimethylation (eEF2K525me3), a PTM catalyzed by the enzyme FAM86A, is unknown. Here, we find that FAM86A methylation of eEF2 regulates nascent elongation to promote protein synthesis and lung adenocarcinoma (LUAD) pathogenesis. The principal physiologic substrate of FAM86A is eEF2, with K525me3 modeled to facilitate productive eEF2-ribosome engagement during translocation. FAM86A depletion in LUAD cells causes 80S monosome accumulation and mRNA translation inhibition. FAM86A is overexpressed in LUAD and eEF2K525me3 levels increase through advancing LUAD disease stages. FAM86A knockdown attenuates LUAD cell proliferation and suppression of the FAM86A-eEF2K525me3 axis inhibits cancer cell and patient-derived LUAD xenograft growth in vivo. Finally, FAM86A ablation strongly attenuates tumor growth and extends survival in KRASG12C-driven LUAD mouse models. Thus, our work uncovers an eEF2 methylation-mediated mRNA translation elongation regulatory node and nominates FAM86A as an etiologic agent in LUAD.

The FAM86 domain of FAM86A confers substrate specificity to promote EEF2-Lys525 methylation.

FAM86A is a class I lysine methyltransferase (KMT) that generates trimethylation on the eukaryotic translation elongation factor 2 (EEF2) at Lys525. Publicly available data from The Cancer Dependency Map project indicate high dependence of hundreds of human cancer cell lines on FAM86A expression. This classifies FAM86A among numerous other KMTs as potential targets for future anticancer therapies. However, selective inhibition of KMTs by small molecules can be challenging due to high conservation within the S-adenosyl methionine (SAM) cofactor binding domain among KMT subfamilies. Therefore, understanding the unique interactions within each KMT-substrate pair can facilitate developing highly specific inhibitors. The FAM86A gene encodes an N-terminal FAM86 domain of unknown function in addition to its C-terminal methyltransferase domain. Here, we used a combination of X-ray crystallography, the AlphaFold algorithms, and experimental biochemistry to identify an essential role of the FAM86 domain in mediating EEF2 methylation by FAM86A. To facilitate our studies, we also generated a selective EEF2K525 methyl antibody. Overall, this is the first report of a biological function for the FAM86 structural domain in any species and an example of a noncatalytic domain participating in protein lysine methylation. The interaction between the FAM86 domain and EEF2 provides a new strategy for developing a specific FAM86A small molecule inhibitor, and our results provide an example in which modeling a protein-protein interaction with AlphaFold expedites experimental biology.

METTL13 Methylation of eEF1A Increases Translational Output to Promote Tumorigenesis.

Increased protein synthesis plays an etiologic role in diverse cancers. Here, we demonstrate that METTL13 (methyltransferase-like 13) dimethylation of eEF1A (eukaryotic elongation factor 1A) lysine 55 (eEF1AK55me2) is utilized by Ras-driven cancers to increase translational output and promote tumorigenesis in vivo. METTL13-catalyzed eEF1A methylation increases eEF1A's intrinsic GTPase activity in vitro and protein production in cells. METTL13 and eEF1AK55me2 levels are upregulated in cancer and negatively correlate with pancreatic and lung cancer patient survival. METTL13 deletion and eEF1AK55me2 loss dramatically reduce Ras-driven neoplastic growth in mouse models and in patient-derived xenografts (PDXs) from primary pancreatic and lung tumors. Finally, METTL13 depletion renders PDX tumors hypersensitive to drugs that target growth-signaling pathways. Together, our work uncovers a mechanism by which lethal cancers become dependent on the METTL13-eEF1AK55me2 axis to meet their elevated protein synthesis requirement and suggests that METTL13 inhibition may constitute a targetable vulnerability of tumors driven by aberrant Ras signaling.