miRNAs and arsenic-induced carcinogenesis

Endoplasmic reticulum stress responses and epigenetic alterations in arsenic carcinogenesis

Arsenic is a well-known human carcinogen whose environmental exposure via drinking water, food, and air impacts millions of people across the globe. Various mechanisms of arsenic carcinogenesis have been identified, ranging from damage caused by excessive production of free radicals and epigenetic alterations to the generation of cancer stem cells. A growing body of evidence supports the critical involvement of the endoplasmic stress-activated unfolded protein response (UPR) in promoting as well as suppressing cancer development/progression. Various in vitro and in vivo models have also demonstrated that arsenic induces the UPR via activation of the PERK, IRE1α, and ATF6 proteins. In this review, we discuss the mechanisms of arsenic-induced endoplasmic reticulum stress and the role of each UPR pathway in the various cancer types with a focus on the epigenetic regulation and function of the ATF6 protein. The importance of UPR in arsenic carcinogenesis and cancer stem cells is a relatively new area of research that requires additional investigations via various omics-based and computational tools. These approaches will provide interesting insights into the mechanisms of arsenic-induced cancers for prospective target identification and development of novel anti-cancer therapies.

Arsenic-induced prostate cancer: an enigma

Arsenic exhibits varying degrees of toxicity depending on its many chemical forms. The carcinogenic properties of arsenic have already been established. However, the precise processes underlying the development of diseases following acute or chronic exposure to arsenic remain poorly known. Most of the existing investigation has focused on studying the occurrence of cancer following significant exposure to elevated levels of arsenic. Nevertheless, multiple investigations have documented diverse health consequences from prolonged exposure to low levels of arsenic. Inorganic arsenic commonly causes lung, bladder, and skin cancer. Some investigations have shown an association between arsenic in drinking water and prostate cancer, but few investigations have focused on exploring this connection. There is currently a lack of relevant animal models demonstrating a clear link between inorganic arsenic exposure and the development of prostate cancer. Nevertheless, studies using cellular model systems have demonstrated that arsenic can potentially promote the malignant transformation of human prostate epithelial cells in vitro. The administration of elevated levels of arsenic has been demonstrated to elicit cell death in instances of acute experimental exposure. Conversely, in cases of chronic exposure, arsenic prompts cellular proliferation and sustains cellular viability, thereby circumventing the constraints imposed by telomere shortening and apoptosis. Furthermore, cells consistently exposed to the stimulus exhibit an augmented ability to invade surrounding tissues and an enhanced potential to form tumors. This review aims to portray mechanistic insights into arsenic-induced prostate cancer.