MicroRNA-195-5p mediates arsenic-induced cytotoxicity in human lung epithelial cells: Beneficial role of plant-derived tannic acid.

Arsenic (As), a highly toxic metalloid, which causes environmental lung diseases and affects millions of people worldwide. Respiratory epithelial cells are essential for maintaining lung homeostasis, aberrant epithelial damage and death due to exposure to a wide range of environmental pollutants, which are considered to be the initial trigger for many pulmonary diseases. Accumulating evidence has shown that microRNAs (miRNAs) appear to be important players in various normal physiological and pathological processes. Therefore, the present study was carried out to examine the cytotoxic effects of a trivalent form of As (As3+) in normal human bronchial (BEAS-2B) and adenocarcinoma alveolar basal (A549) epithelial cells and the role of miR-195-5p. Further, we also explored the protective effects of a natural dietary polyphenol tannic acid (TA). As3+ (1 µM) treatment in BEAS-2B cells for 24 h induced cytotoxicity by decreasing the cell viability, mitochondrial membrane potential (ΔΨm) and inducing reactive oxygen species (ROS) generation, lipid peroxidation (LPO), cell cycle arrest, and apoptosis, which was associated with a significantly higher level of miR-195-5p expression compared with vehicle control. Forced expression of miR-195-5p alone suppressed cell survival, ΔΨm, regulated cell cycle distribution and induced ROS generation in BEAS-2B cells. As expected, miR-195-5p inhibition effectively rescued BEAS-2B cells from As3+-mediated toxicity, confirming the involvement of miR-195-5p in the cytotoxic effects of As3+. Further, TA pre-treatment expressively alleviated As3+-induced toxicity by suppressing ROS production, miR-195-5p expression, and increasing ΔΨm. These in vitro results indicate that miR-195-5p may be useful as a therapeutic target for treating As3+ toxicity.