WTAP upregulates HK2 expression via m6A methylation to reprogram cell glycolysis and stemness under Cr(VI) exposure

Epidemiological investigations indicate that hexavalent chromium (Cr(VI)) exposure induces lung carcinogenesis, but the underlying epigenetic mechanisms of Cr(VI)-induced carcinogenesis remain to be further investigated. In this study, we used a Cr(VI)-exposed mouse model to demonstrate elevated m6A modification levels in lung tissues, and further used Cr(VI) transformed cell model (CrT) to identify that Cr(VI) induced the expression of Wilms' tumor 1-associated protein (WTAP), a key localization gene for m6A RNA methylation modification, in a time and concentration-dependent manner, and proved that WTAP enhanced cell proliferation and was involved in the maintenance of cellular stemness through up-regulating CD133 expression. Additionally, WTAP upregulated the expression of hexokinase 2 (HK2), a rate-limiting glycolytic enzyme, while knocking down HK2 significantly reduced WTAP's ability to promote CD133 expression. Furthermore, we identified m6A modification site on HK2 mRNA bound to the WTAP-VIRMA complex by molecular docking model and m6A MeRIP-qPCR assay. Notably, both WTAP and HK2 were significantly high expression in blood samples from chromium-exposed occupational workers, and their expressions were significantly positively correlated. We also demonstrated that WTAP was significantly overexpressed in lung cancer cell, and found that the overall survival rate of lung squamous cell carcinoma patients with high expression of WTAP was significantly reduced. Collectively, our study demonstrated that WTAP is a novel mechanism of Cr(VI)-induced malignant transformation of cells, and further revealed that WTAP mediates the Cr(VI)-induced glycolytic remodeling and enhances the cellular stemness via HK2. WTAP and HK2 represent promising biomarkers for chromium-exposed populations.