Circulating miRNAs Associated with Arsenic Exposure

Arsenic (As) is a toxic metalloid. Inorganic arsenic (iAs) is a form of As commonly found in drinking water and in some foods. Overwhelming evidence suggests that people chronically exposed to iAs are at risk of developing cancer or cardiovascular, neurological, and metabolic diseases. Although the mechanisms underlying iAs-associated illness remain poorly characterized, a growing body of literature raises the possibility that microRNAs (miRNAs), post-transcriptional gene suppressors, may serve as mediators and/or early indicators of the pathologies associated with iAs exposure. To characterize the circulating miRNA profiles of individuals chronically exposed to iAs, samples of plasma were collected from 109 healthy residents of the city of Zimapán and the Lagunera area in Mexico, the regions with historically high exposures to iAs in drinking water. These plasma samples were analyzed for small RNAs using high-throughput sequencing and for iAs and its methylated metabolites. Associations between plasma levels of arsenic species and miRNAs were evaluated. Six circulating miRNAs (miRs-423-5p, -142-5p -2, -423-5p +1, -320c-1, -320c-2, and -454-5p), two of which have been previously linked to cardiovascular disease and diabetes (miRs-423-5p, -454-5p), were found to be significantly correlated with plasma MAs. No miRNAs were associated with plasma iAs or DMAs after correction for multiple testing. These miRNAs may represent mechanistic links between iAs exposure and disease or serve as markers of disease risks associated with this exposure.