Chronic cadmium exposure promotes TRPM7-dependent acquisition of a myofibroblast-like phenotype in pancreatic stellate cells.

Abstract

Cadmium (Cd) is a metallic pollutant which has been classified as a possible pancreatic carcinogen. Cd uses similar ion channels than divalent cations to accumulate into the cells. These include the Transient Receptor Potential Cation Channel Subfamily M Member 7 (TRPM7) which has been also shown as a biomarker of pancreatic cancer. Pancreatic carcinogenesis is associated with the establishment of a fibrous stroma induced by pancreatic stellate cell (PSC) activation. Although several stress factors have been identified as activators of PSCs, the impact of pollutants, particularly Cd, is still unknown. Here, we chronically exposed human PSCs to Cd and we observed that Cd-exposed cells acquired a myofibroblast-like phenotype. Moreover, TRPM7 expression and activity were upregulated following Cd exposure. Both TRPM7 inhibition by silencing or NS8593 treatment prevented the Cd-induced PSC cell migration indicating that TRPM7 regulated PSC activation. We used a model of indirect co-culture to study the impact of PSC on MIA PaCa-2 cancer cell migration. Interestingly, we showed that Cd-exposed PSCs stimulated MIA PaCa-2 cancer cell migration to a greater extent than non-exposed PSCs. TRPM7 inhibition in PSCs abolished the migration of cancer cells. Finally, in a mouse model with the KRAS^G12D mutation inducing spontaneous pancreatic intraepithelial neoplasia, Cd exposure aggravates collagen deposition in fibrotic areas showing high α-SMA and TRPM7 expressions. In summary, our study showed that Cd exposure upregulates TRPM7 leading to PSC activation and aggravation of precancerous pancreatic fibrosis in vivo.