Chronic polycyclic aromatic hydrocarbon exposure causes DNA damage and genomic instability in lung epithelial cells

// Hongzhen Bai 1, 2, * , Min Wu 2, * , Hongjian Zhang 1 and Guping Tang 2 1 State Key Laboratory of Industrial Control Technology, College of Control Science and Engineering, Zhejiang University, Hangzhou 310028, China 2 Institute of Chemical Biology and Pharmaceutical Chemistry, Zhejiang University, Hangzhou 310028, China * These authors have contributed equally to this work Correspondence to: Guping Tang, email: tangguping@zju.edu.cn Keywords: human lung epithelial cells, polycyclic aromatic hydrocarbon, genotoxicity, cell cycle, apoptosis Received: November 11, 2016 Accepted: August 26, 2017 Published: September 15, 2017 ABSTRACT Cell exposure to atmospheric polycyclic aromatic hydrocarbons (PAHs) is closely associated with DNA damage and genomic instability. We assessed the mechanisms of chronic and acute PAH exposure-induced genotoxicity in two human lung epithelial cell lines, A549 and NC-H1975. We sampled atmospheric PAHs at the Xixi Campus, Zhejiang University in Hangzhou, China during August (non-haze episode) and November (haze episode) 2015. We identified vehicle emissions as a dominant anthropogenic PAH source in our study. PAHs were extracted according to the United States Environmental Protection Agency Method TO-13A. We found that chronic PAH exposure saturated lung cell xenobiotic metabolic pathways, promoting intercellular reactive oxygen species production and accumulation. Chronic alteration of the cellular redox status resulted in DNA damage and genomic instability. Chronic PAH exposure also perturbed the cellular DNA damage response, inducing S phase arrest and inhibiting apoptosis. Dysregulation of PAH metabolism and the DNA damage response altered cellular homeostasis and increased cell susceptibility to subsequent PAH exposures, thereby enhancing the likelihood of genomic mutation and instability.