Mis-regulated epigenetic modifications in RNAs are associated with human
cancers. The transfer RNAs (tRNAs) are the most heavily modified
RNA species in cells; however, little is known about the functions of
tRNA modifications in
cancers. In this study, we uncovered that the expression levels of
tRNA N7-methylguanosine (m7G)
methyltransferase complex components
methyltransferase-like 1 (METTL1) and WD repeat domain 4 (WDR4) are significantly elevated in human
lung cancer samples and negatively associated with patient prognosis. Impaired m7G
tRNA modification upon METTL1/WDR4 depletion resulted in decreased cell proliferation, colony formation, cell invasion, and impaired tumorigenic capacities of
lung cancer cells in vitro and in vivo. Moreover, gain-of-function and mutagenesis experiments revealed that METTL1 promoted
lung cancer growth and invasion through regulation of m7G
tRNA modifications. Profiling of
tRNA methylation and mRNA translation revealed that highly translated mRNAs have higher frequencies of m7G
tRNA-decoded
codons, and knockdown of METTL1 resulted in decreased translation of mRNAs with higher frequencies of m7G
tRNA codons, suggesting that
tRNA modifications and codon usage play an essential function in mRNA translation regulation. Our data uncovered novel insights on mRNA translation regulation through
tRNA modifications and the corresponding
mRNA codon compositions in
lung cancer, providing a new molecular basis underlying
lung cancer progression.