N6-methyladenosine plays a dual role in arsenic carcinogenesis by temporal-specific control of core target AKT1

High-profile RNA epigenetic modification N⁶-methyladenosine (m⁶A), as a double-edged sword for Cancer, can either promote or inhibit arsenic-induced skin carcinogenesis. However, the core m⁶A-target gene determining the duality of m⁶A and the regulatory mechanism of m⁶A on the core gene are still poorly understood. Based on m⁶A microarray detection, integrated multi-omics analysis, and further experiments in vitro and in vivo, we explored the molecular basis for the dual role of m⁶A 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 m⁶A-regulatory network in arsenic carcinogenicity. The m⁶A level on Akt1 mRNA (3'UTR, CDS, and 5'UTR) dynamically changed in different stages of arsenic carcinogenesis. The m⁶A writer METTL3-catalyzed upregulation of m⁶A promotes Akt1 expression by elevating m⁶A reader YTHDF1-mediated Akt1 mRNA stability in As-treated and As-transformed cells, while the m⁶A eraser FTO-catalyzed downregulation of m⁶A promotes Akt1 expression mainly by inhibiting m⁶A reader YTHDF2-mediated Akt1 mRNA degradation in As-tumorigenic cells. Furthermore, upregulation of m⁶A 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 m⁶A prevents Akt upregulation in As-treated cells but promotes Akt upregulation in As-tumorigenic cells. Both inhibitors targeting the m⁶A writer and eraser can inhibit the AKT1-mediated proliferation of As-tumorigenic cells by breaking the balance of m⁶A regulators. Our results demonstrated that Akt1 is the core hub determining m⁶A as a double-edged sword. Changed m⁶A 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.

Carcinogen; PDK1; PHLPP2; m(6)A; m(6)A regulators.