Arsenic regulates ALKBH1 abundance and substrate specificity to promote translation and tumorigenicity

Here we show a novel role for arsenic in regulating the abundance and function of the demethylase activity of ALKBH1 in arsenic-induced skin cancer. We demonstrate that ALKBH1 is upregulated in response to acute and chronic arsenic exposure. In chronic arsenic-exposed keratinocytes, ALKBH1 promotes tumorigenicity, as knockdown of ALKBH1 leads to decreased tumorigenicity. ALKBH1 as a demethylase has several substrates and knockdown of ALKBH1 in arsenic-induced keratinocytes lead to increased m6A in mRNA. We identify that ALKBH1 demethylates m6A in vitro in an arsenic-dependent manner. Arsenic binds to the ALKBH1 protein via two cysteine residues to regulate the m6A RNA demethylase activity of ALKBH1. m6A sequencing identifies that ALKBH1 regulates m6A demethylation on the NR2C2 transcript to modulate NR2C2 protein translation in a YTHDF1-dependent manner. Knockdown of ALKBH1 leads to increased NR2C2 expression, which, in turn, leads to decreased mTOR signaling and global translation. Our findings demonstrate a novel role for arsenic in regulating ALKBH1 abundance and activity and add new mechanistic insights into arsenic-induced skin tumorigenicity. m6A-IP-Sequencing of control and ALKBH1-knockdown arsenic-transformed keratinocytes in duplicate