N6-methyladenosine mediates arsenite-induced human keratinocyte transformation by suppressing p53 activation

N-6-methyladenosine (m(6)A), the most abundant and reversible RNA modification, plays critical a role in tumorigenesis. However, whether m(6)A can regulate p53, a leading antitumor protein remains poorly understood. In this study, we explored the regulatory role of m(6)A on p53 activation using an arsenitetransformed keratinocyte model, the HaCaT-T cell line. We created the cell line by exposing human keratinocyte HaCaT cells to 1 mu M arsenite for 5 months. We found that the cells exhibited an increased m 6 A level along with an aberrant expression of the methyltransferases, demethylase, and readers of m(6)A. Moreover, the cells exhibited decreased p53 activity and reduced p53 phosphorylation, acetylation, and transactivation with a high nucleus export rate of p53. Knockdown of the m(6)A methyltransferase, METTL3 significantly decreased m(6)A level, restoring p53 activation and inhibiting cellular transformation phenotypes in the arsenite-transformed cells. Further, using both a bioinformatics analysis and experimental approaches, we demonstrated that m(6)A downregulated the expression of the positive p53 regulator, PRDM2, through the YTHDF2-promoted decay of PRDM2 mRNAs. We showed that m(6)A upregulated the expression of the negative p53 regulator, YY1 and MDM2 through YTHDF1-stimulated translation of YY1 and MDM2 mRNA. Taken together, our study revealed the novel role of m(6)A in mediating arsenite-induced human keratinocyte transformation by suppressing p53 activation. This study further sheds light on the mechanisms of arsenic carcinogenesis via RNA epigenetics. (C) 2020 Elsevier Ltd. All rights reserved.