Regulation of UGT2A1 by miR‐196a & miR‐196b and Its Implications for Lung Cancer Risk

Abstract

Polycyclic aromatic hydrocarbons (PAH) are a class of highly lipophilic and mutagenic carcinogenic compounds found in tobacco smoke and incomplete combustion reactions. Once inside the cell, PAHs are oxidized by cytochrome P450s 1C1 and 1B1 to form reactive species that can form DNA adducts. PAHs are primarily detoxified by the UDP‐glucuronosyltransferase (UGT) family of enzymes, which comprise a major family of phase II metabolism responsible for the detoxification of a variety of endogenous and exogenous compounds including steroids, many drugs and chemotherapeutic agents, and carcinogens. UGT2A1 is an aero‐digestive tract‐expressing enzyme shown to be highly selective toward a broad range PAHs and is expressed in tobacco target tissues, including lung. microRNA (miRNA) are short, noncoding RNA sequences that play a role in translational regulation of gene expression by binding primarily to the 3′ untranslated regions (UTR) of mRNA. Significant (P<0.05 and P<0.001) decreases in luciferase activity were observed in cells over‐expressing heterologous vectors containing the 3′‐untranslated region (UTRs) of UGT2A1 with the miR‐196a and miR‐196b mimics, respectively. Pull‐down assays revealed miR‐196a and miR‐196b bound to the 3′ UTR of UGT2A1 at 3.4‐and 5.3‐fold higher levels, respectively, compared to the coding region control sequence. In the lung cancer cell lines, H1944 and H146, a significant trend is observed when cells were transfected with increasing levels of miR‐196a and miR‐196b (Ptrend=0.0065 and Ptrend=0.0114 for H1944, and Ptrend=0.0219 and Ptrend=0.0091 for H146, respectively). These data indicate that miR‐196a and miR‐196b may be important in regulating UGT2A1 expression in human tissues and may be potential biomarkers for cancer risk in smokers.Support or Funding InformationNational Institute of Environmental Health Sciences (NIEHS) of the National Institute of Health (NIH) to Dr. Philip Lazarus (Grant R01‐ES025460) and the Health Sciences and Services Authority of Spokane, WA (Grant WSU002292).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.