ALKBH5 enhances cadmium-induced stemness enrichment and proliferation of colon cancer cells via m6A-dependent regulation of AXIN2 and activation of Wnt/β-catenin signaling.

Cadmium (Cd) is a carcinogenic heavy metal with a long biological half-life that has been implicated in the development of colorectal cancer (CRC). However, the mechanisms underlying Cd-induced CRC malignancy remain incompletely understood. Cancer stem cells (CSCs), which are characterized by self-renewal, pluripotency and unlimited proliferative potential, are believed to be responsible for the initiation, progression and recurrence of CRC. The aim of this study was to investigate the long-term effects of Cd on stemness enrichment and proliferation in colon cancer cells, and to identify the key signaling pathways involved. Our results demonstrated that chronic Cd exposure enhanced sphere formation and increased the expression of stem cell-like markers (CD44, OCT4, SOX2, and NANOG) in colon cancer cells. Colony formation assays, CCK-8 assays, and xenograft models in nude mice further confirmed that Cd significantly promoted cell proliferation. Mechanistically, Cd reduced N6-methyladenosine (m6A) methylation in mRNA by upregulating the m6A demethylase ALKBH5. Knockdown of ALKBH5 attenuated Cd-induced stemness enrichment and proliferation. ALKBH5 was found to demethylate the m6A of AXIN2 mRNA, reducing IGF2BP1-mediated stabilization of AXIN2 mRNA, leading to its destabilization and reduced expression, which subsequently hyperactivated the Wnt/β-catenin signaling. These results highlight the role of the ALKBH5-m6A-AXIN2-Wnt/β-catenin axis in Cd-induced stemness and proliferation in colon cancer, offering new insights into Cd-associated CRC development.