tRNASer overexpression induces adaptive mutations in NSCLC tumors

tRNAs are a driving force of genome evolution in Yeast and Bacteria. Their deregulation is frequently observed in tumors with Serine tRNAs being often overexpressed. This has important functional consequences, such as increased metabolism and tumor growth. In yeast, time and chemical stimulus boost alterations in the genome driven by tRNA deregulation. Therefore, we hypothesized that tRNA deregulation may contribute to the increased genome instability observed in tumors. To study the effect of tRNA deregulation in tumors, we overexpressed tRNA-Ser-AGA-2-1 in a NSCLC cell line, H460. This cell line and a Mock (control) were xenografted in nude mice and collected at 3 timepoints: T1-Naive; T2-Treated once with cisplatin/vehicle and; T3) treated twice with cisplatin/vehicle. These tumors were characterized by WES, RNAseq and Mass Spectrometry and the data obtained was integrated. The tumor mutation burden was increased in T3 tRNASerOE tumors, regardless of treatment. Although in T1 Mock and tRNASer tumors have a similar number of variants, in T2&3, tRNASerOE tumors display two times more variants than Mock tumors regardless of treatment. Interestingly, tRNASerOE exclusive variants favor proliferation and therapy resistance, which is in line with the phenotypes observed and supported by RNAseq and proteomics data. In conclusion, tRNASerOE increases the tumor mutation burden and the variants detected favor tumor growth, proving tRNA deregulation is enough to induce adaptive mutations in the genome.