METTL1/WDR4 mediated tRNA N7-methylguanosine (m7G) modifications promote mRNA translation and lung cancer progression [TRAC-seq]

The tRNA N7-methylguanosine (m7G) modification is not essential for yeast growth, but in mammals mis-regulations of tRNA m7G modification cause stem cell defect and developmental disorders. Here we found that tRNA m7G methyltransferase complex components METTL1 and WDR4 are elevated in lung cancer tissues and associated with poor lung cancer prognosis. Functionally, depletion of METTL1 or WDR4 suppresses proliferation, migration, and invasion of lung cancer cells. In addition, forced expression of METTL1 or WDR4 promotes lung cancer progression depending on the tRNA m7G methyltransferase activity. Mechanistically, METTL1 knockdown leads to reduced tRNA m7G modification and decreased expression of m7G-modified tRNAs. Depletion of METTL1 selectively reduces the translation of a subset of oncogenic transcripts, including the genes related to cell proliferation in a m7G related codon dependent manner. Our study uncovered a new layer of translation regulation mechanism mediated by tRNA m7G modification, provided strong evidence to support the important physiological function of mis-regulated tRNA modification in cancer, and suggested that targeting METTL1 could be a promising strategy for lung cancer treatment. TRAC-Seq were developed to identify the tRNA m7G methylome in lung cancer cell line A549.