N-methyladenosine plays a dual role in arsenic carcinogenesis by temporal-specific control of core target AKT1.

High-profile RNA epigenetic modification N-methyladenosine (mA), as a double-edged sword for cancer, can either promote or inhibit arsenic-induced skin carcinogenesis. However, the core mA-target gene determining the duality of mA and the regulatory mechanism of mA on the core gene are still poorly understood. Based on mA microarray detection, integrated multi-omics analysis, and further experiments in vitro and in vivo, we explored the molecular basis for the dual role of mA in cancer induced by environmental pollutants using models in different stages of arsenic carcinogenesis, including As-treated, As-transformed, and As-tumorigenic cell models. We found that the key proliferative signaling node AKT1 is in the center of the mA-regulatory network in arsenic carcinogenicity. The mA level on AKT1 mRNA (3'UTR, CDS, and 5'UTR) dynamically changed in different stages of arsenic carcinogenesis. The mA writer METTL3-catalyzed upregulation of mA promotes AKT1 expression by elevating mA reader YTHDF1-mediated AKT1 mRNA stability in As-treated and As-transformed cells, while the mA eraser FTO-catalyzed downregulation of mA promotes AKT1 expression mainly by inhibiting mA reader YTHDF2-mediated AKT1 mRNA degradation in As-tumorigenic cells. Furthermore, upregulation of mA inhibits the expression of AKT1 negative regulator PHLPP2 and promotes the expression of AKT1 positive regulator PDK1. These changes in AKT1 regulators result in AKT1 activation by upregulating AKT1 phosphorylation at S473 and T308. Interestingly, the FTO-catalyzed decrease in mA prevents AKT upregulation in As-treated cells but promotes AKT upregulation in As-tumorigenic cells. Both inhibitors targeting the mA writer and eraser can inhibit the AKT1-mediated proliferation of As-tumorigenic cells by breaking the balance of mA regulators. Our results demonstrated that AKT1 is the core hub determining mA as a double-edged sword. Changed mA dynamically upregulates the expression and activity of AKT1 in different stages of arsenic carcinogenesis. This study can advance our understanding of the dual role and precise time-specific mechanism of RNA epigenetics involved in the carcinogenesis of hazardous materials.