SILAC-based quantitative proteomic analysis reveals molecular alterations in human skin keratinocytes upon chronic exposure to arsenic

Chronic exposure to arsenic is associated with dermatological and non-dermatological disorders. Consumption of arsenic contaminated drinking water results in accumulation of arsenic in liver, spleen, kidneys, lungs and gastrointestinal tract. Although, arsenic is cleared from these sites, a substantial amount of residual arsenic is left in keratin-rich tissues such as skin. Epidemiological studies on arsenic suggest the association of skin cancer upon arsenic exposure, however, the exact mechanism of arsenic induced carcinogenesis is not completely understood. We have developed a cell line-based model to understand the molecular mechanisms involved in arsenic mediated toxicity and carcinogenicity. Human skin keratinocyte cell line, HaCaT was exposed to 100nM sodium arsenite for six months. We observed an increase in the basal ROS levels in arsenic exposed cells along with the increase in anti-apoptotic proteins. SILAC-based quantitative proteomics approach resulted in the identification and quantitation of 2,181 proteins of which 39 proteins were found to be overexpressed (≥2-fold) and 56 downregulated (≤2-fold) upon chronic arsenic exposure. Our study provides comprehensive insights into the molecular basis of chronic arsenic exposure on skin.