Abstract 6160: Targeting RNA N6-methyladenosine methyltransferase, METTL3 activates p53 and apoptosis pathways in osteosarcoma cells

Abstract Osteosarcoma (OS) is a malignant tumor which is mesenchymal origin from bone stroma. The 5-year overall survival of localized OS is approximately 70%, however patients who have metastasis to other organs, mostly lung, have a poor 5-year survival rate, approximately 20%. Recently, oncogenic role of Methyltransferase-like 3 (METTL3), which is the only catalytic subunit of RNA N6-Methyladenosine methyltransferase complex, has been suggested, but its mechanism in OS is still unclear. To elucidate the roles of METTL3 in OS, we generated METTL3 knock-out U2OS osteosarcoma cell lines by CRISPR knock-out system. Knock-out of METTL3 decreased cell proliferation on U2OS cells, which was assessed by WST-1 assay and manual cell counting assay. Also, RNA-sequencing was conducted in METTL3 wild type and knock-out cell lines. Gene set enrichment analysis (GSEA) revealed that gene sets of ‘Programmed cell death’ in gene ontology (GO) category, ‘p53 pathway’ and ‘Apoptosis’ in HALLMARK gene sets, and ‘p53 signaling pathway’ and ‘Apoptosis’ in KEGG pathway were enriched in METTL3 knock-out cells. To validate the result of GSEA in our METTL3 knock-out cells, mRNA and protein levels of GADD45A and CDKN1A, which are downstream targets of p53, and BAX and BAK, which are apoptosis-related molecules induced by p53, were detected by real-time PCR and western blot, respectively, and these genes were upregulated in METTL3 knock out cell lines. Collectively, these results suggest that inhibition of METTL3 is potential therapeutic targets against OS by activating p53 and apoptosis pathways. Citation Format: Seungjae Shin, Yumi Oh, Yoojin Yang, Sung-Yup Cho. Targeting RNA N6-methyladenosine methyltransferase, METTL3 activates p53 and apoptosis pathways in osteosarcoma cells [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 6160.