Arsenic and microRNA expression

Abstract

Arsenic is a naturally occurring metalloid that poses a major threat to worldwide human health. The most toxic form of arsenic is inorganic arsenic, which has been classified by the International Agency for Research on Cancer as a group 1 carcinogenic to humans. This classification is based on the increased incidence of primary skin cancer, as well as lung and urinary bladder cancer after exposure to arsenic. Exposure to arsenic typically occurs by oral consumption of contaminated drinking water, soil, and food or by inhalation in an industrial work setting. The main exposure route to inorganic arsenic remains dietary, particularly in infants. This review describes our current understanding of the molecular mechanisms through which arsenic causes harm, although the toxic effects associated with inorganic arsenic exposure are not well understood. Arsenic toxicokinetics varies depending on its form and on several factors such as life-stage, gender, nutritional status, and genetic polymorphisms. MicroRNAs play a key role in many physiological and pathological cellular processes, and they are powerful regulators of gene expression under inorganic arsenic exposure. Several in vitro and in vivo studies on the effect of inorganic arsenic exposure on the microRNA expression profile showed that micro- RNAs misregulation is involved in a variety of human tumors and in angiogenesis.