Polycyclic aromatic hydrocarbons—induced ROS accumulation enhances mutagenic potential of T‐antigen from human polyomavirus JC

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are the products of incomplete combustion of organic materials, which are present in cigarette smoke, deep-fried food, and in natural crude oil. Since PAH-metabolites form DNA adducts and cause oxidative DNA damage, we asked if these environmental carcinogens could affect transforming potential of the human Polyomavirus JC oncoprotein, T-antigen (JCV T-antigen). We extracted DMSO soluble PAHs from Deepwater Horizon oil spill in the Gulf of Mexico (oil-PAHs), and detected several carcinogenic PAHs. The oil-PAHs were tested in exponentially growing cultures of normal mouse fibroblasts (R508), and in R508 stably expressing JCV T-antigen (R508/T). The oil-PAHs were cytotoxic only at relatively high doses (1:50–1:100 dilution), and at 1:500 dilution the growth and cell survival rates were practically unaffected. This non-toxic dose triggered however, a significant accumulation of reactive oxygen species (ROS), caused oxidative DNA damage and the formation of DNA double strand breaks (DSBs). Although oil-PAHs induced similar levels of DNA damage in R508 and R508/T cells, only T-antigen expressing cells demonstrated inhibition of high fidelity DNA repair by homologous recombination (HRR). In contrast, low-fidelity repair by non-homologous end joining (NHEJ) was unaffected. This potential mutagenic shift between DNA repair mechanisms was accompanied by a significant increase in clonal growth of R508/T cells chronically exposed to low doses of the oil-PAHs. Our results indicate for the first time carcinogenic synergy in which oil-PAHs trigger oxidative DNA damage and JCV T-antigen compromises DNA repair fidelity.

A bioenergetics assay for studying the effects of environmental stressors on mitochondrial function in vivo in zebrafish larvae

“…Based on in vitro data obtained from mammalian cells exposed to various concentrations of oxygen, Bishop & Brand (2000) have proposed that an increase in non-mitochondrial oxygen consumption might serve as a protective mechanism to remove oxygen when it is present at potentially harmful concentrations. This suggestion provides a plausible explanation for the significant increase in non-mitochondrial oxygen consumption observed in our study, as it would help delay or prevent PAH-induced increases in ROS generation and oxidative stress (Arzuaga and Elskus, 2010; Timme-Laragy et al, 2009; Wilk et al, 2013). Since we are currently unable to partition total mitochondrial respiration due to ATP turnover and proton leak in larvae, future research will aim to determine why mitochondrial respiration was decreased after FL exposure.…”

Environmental stress in the Gulf of Mexico and its potential impact on public health

“…Although chronic effects of low doses of these substances on human health are not well defined, several PAHs are classified as potent carcinogens, which form covalent DNA adducts and cause oxidative DNA damage (Ji et al, 2010; Liu et al, 2010; Seike et al, 2003; Xue and Warshawsky, 2005). In respect to cancer risk, these PAH-induced primary DNA lesions may result in the accumulation of random mutations when cellular mechanisms responsible for DNA repair fidelity are compromised by inherited mutations of genes involved in DNA repair (Shields, 1993), excessive DNA damage, or by oncogenic viruses (Morales-Sanchez and Fuentes-Panana, 2014; White et al, 2005; Wilk et al, 2013). Further epidemiological studies are required to verify if indeed PM-induced DNA damage can contribute to the increased incidence of cancer especially in individuals whom are already predisposed to cancer by inherited mutations or oncogenic viruses.…”

PM2.5induces embryonic growth retardation: Potential involvement of ROS-MAPKs-apoptosis and G0/G1 arrest pathways

“…PM 2.5 is a complex mixture that is composed of sulfates, nitrates, elemental and organic carbon (EC and OC), organic compounds, and various metals (Ostro et al, ; Lodovici and Bigagli, ). Previous studies indicated that fine particles, polycyclic aromatic hydrocarbons, metals of PM 2.5 can enhance ROS generation and lead to cell damage (Lodovici and Bigagli, ; Wilk et al, ; Wang et al, ). Our cooperative research team had tested the chemical composition of the PM 2.5 collected at the same place and time.…”