N6-methyadenosine modified KREMEN2 promotes tumorigenesis and malignant progression of high grade serous ovarian cancer

High-grade serous ovarian cancer (HGSOC) remains the most lethal female cancer by far. Herein, clinical HGSOC samples had higher N 6 -methyladenosine (m 6 A) modification than normal ovarian tissue, and its dysregulation had been reported to drive aberrant transcription and translation programs. However, Kringle containing transmembrane protein 2 (KREMEN2) and its m 6 A modification have not been fully elucidated in HGSOC. In this study, the data from the high-throughput mRNA sequencing (RNA-seq) of clinical samples were processed using the weighted correlation network analysis (WGCNA) and functional enrichment analysis. Results revealed that KREMEN2 was a driver gene in the tumorigenesis of HGSOC and a potential target of m 6 A demethylase fat-mass and obesity-associated protein (FTO). KREMEN2 and FTO levels were upregulated and downregulated, respectively, and correlation analysis showed a significant negative correlation in HGSOC samples. Importantly, upregulated KREMEN2 was remarkably associated with lymph node (LN) metastasis, distant metastasis, peritoneal metastasis, and high FIGO stage (Ⅲ/Ⅳ), independent of the age of patients. KREMEN2 promoted the growth of HGSOC in vitro and in vivo , which was dependent on FTO. The methylated RNA immunoprecipitation-qPCR and RNA immunoprecipitation assays were performed to verify the m 6 A level and sites of KREMEN2. FTO overexpression significantly decreased m 6 A modification in 3'UTR and 5'UTR regions of KREMEN2 mRNA and downregulated its expression. In addition, we found that FTO-mediated m 6 A modification of KREMEN2 mRNA was recognized and stabilized by the m 6 A reader IGF2BP1 rather than IGF2BP2 or IGF2BP3. This study highlights the m 6 A modification of KREMEN2 and extends the importance of RNA epigenetics in HGSOC.