LAUSR

BACKGROUND Intrahepatic cholangiocarcinoma (ICC) is a highly aggressive disease with the underlying mechanisms poorly understood. YTHDF1, an m6 A reader protein, has important physiological functions in regulation of tumor development. However, the effect of YTHDF1 on ICC progression remains unknown yet. METHODS The expression level of YTHDF1 in human ICC tissue was examined in the Cancer Genome Atlas (TCGA) database and our cohort. The role of YTHDF1 was detected using two human ICC cell lines in vitro. An ICC tumorigenesis mouse model was established via hydrodynamic transfection of AKT/YAP plasmids. m6 A sequencing (m6 A-seq), RNA immunoprecipitation sequencing (RIP-seq), and RNA-seq were carried out to explore the mechanism of YTHDF1 modulating ICC progression. RESULTS Here we find that YTHDF1 is up-regulated in ICC and associated with shorter survival of ICC patients. Depletion of YTHDF1 inhibits cell proliferation, cell migration and invasion, while overexpression of wild type YTHDF1, but not m6 A reader domain mutant YTHDF1, significantly enhances tumor cell growth and aggressive abilities in vitro. Moreover, overexpression of YTHDF1 promotes the AKT/YAP transfection-induced orthotopic ICC tumorigenesis and progression in vivo. Mechanistically, we identify that YTHDF1 regulates the translation of epidermal growth factor receptor (EGFR) mRNA via binding m6 A sites in the 3'-UTR of EGFR transcript, thus leading to aberrant activities of downstream signal pathways that impact tumor progression. CONCLUSION Our data uncover the oncogenic function and m6 A reader-dependent mechanism of YTHDF1 in regulation of ICC progression. Restricting abnormal oncogenic mRNA translation by targeting YTHDF1 may be a novel and promising strategy for ICC treatment.