Hyper-methylated miR-203 dysregulates ABL1 and contributes to the nickel-induced tumorigenesis

Nickel compounds have been found to be carcinogenic based upon epidemiological, animal and cell culture studies. Previous studies suggest that epigenetic mechanisms play a role in Nickel-induced carcinogenesis such as DNA methylation and histone modification. In this study, we investigated the role of microRNAs (miRNAs) in nickel-induced carcinogenesis. The expression of several miRNAs which may function as tumor suppressor genes revealed a strong downregulation of miR-203 in Ni₃S₂-transformed 16HBE cells (NSTCs). Meanwhile, we observed hypermethylation of CpGs in miR-203 promoter and first exon area, and proved that the hyper-methylated miR-203 was involved in the Nickel-induced tumorigenesis. Moreover, we identified that miR-203 may suppress the tumorigenesis at least in part through negatively regulating its target gene ABL1. Our findings indicate that DNA methylation-associated silencing of tumor suppressor miRNAs contributes to the development of Nickel-induced cancer.