LAUSR

N6-methyladenosine RNA methylation is one of the most abundant post transcriptional modifications in eukaryotic messenger RNAs and plays crucial roles in cancer development and progression. YTHDF1 is an m6A reader protein and has been reported to increase the translation of mRNAs in cooperation with YTHDF3. In gastric cancer, YTHDF1 was reported to be overexpressed in cancer tissues, but detailed effects of YTHDF1 in cancer immunity have not been fully elucidated. In RNA sequencing data from a TGCA gastric cancer cohort, the expression of YTHDF1 was inversely correlated with the cytotoxic T cell markers, such as CD8A, GZMA, and GZMB. To investigate the effect of YTHDF1 overexpression on gene expression regulation in protein levels, we performed the proteomic analysis for newly synthesized proteins using non-canonical amino acid azidohomoalanine and click chemistry tagging reaction in the presence of interferon-γ (IFN-γ). Protein synthesis of genes in ‘DNA damage response’ and ‘DNA repair’ gene sets increased in YTHDF1-overexpressed samples. On the contrary, protein synthesis of genes in ‘Allograph rejection’, ‘NK cell mediated cytotoxicity’, and ‘NF-κB signaling’ gene sets decreased in YTHDF1-overexpressed samples. Especially, YTHDF1 reduced basal expression of DNA damage marker, γH2AX, suggesting that DNA damage repair was enhanced by YTHDF1 overexpression. Our study suggests that YTHDF1 plays pervasive roles in DNA repair and cancer immunity by regulating gene expression in protein levels. Citation Format: Dongjun Jang, Hae Rim Jung, Jaeik Oh, Sung-Yup Cho. RNA N6-methyladenosine binding protein, YTHDF1 regulates DNA repair and cancer immunity in protein synthesis levels. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3716.