Photoirradiation of Polycyclic Aromatic Hydrocarbons with UVA Light – A Pathway Leading to the Generation of Reactive Oxygen Species, Lipid Peroxidation, and DNA Damage

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are a class of genotoxic environmental contaminants. We have long been interested in determining the mechanisms by which PAHs induce genotoxicity. Although the metabolic activation of PAHs leading to biological activities has been well studied, the photo-induced activation pathway has seldom reported. In this paper, we review the study of photoirradiation of PAHs with UVA irradiation results in (i) cytotoxicity and DNA damage (ii) DNA single strand cleavage; (iii) formation of 8-hydroxy-2'-deoxyguanosine adduct (8-OHdG), and (iv) formation of lipid peroxidation. Evidence has been shown that these photobiological activities are mediated by reactive oxygen species (ROS).

Phototoxicity and Environmental Transformation of Polycyclic Aromatic Hydrocarbons (PAHs)—Light-Induced Reactive Oxygen Species, Lipid Peroxidation, and DNA Damage

“…As described previously, upon absorbing light energy, the excited PAHs can act as sensitizers to transfer energy or electrons to molecular oxygen to form ROS [27,150]. Conceivably, humans concomitantly exposed to PAHs and UV light may incur lipid peroxidation resulting in significant biological consequences.…”

The role of antioxidants in photoprotection: A critical review

“…Environmental pollutants such as polycyclic aromatic hydrocarbons from fossil fuel combustion can be activated and converted into endogenous ROS via quinone intermediates. 12 In vitro and in vivo studies demonstrate that a common polycyclic aromatic hydrocarbons, benzoapyrene and its intermediates, act as photosensitizers, which upon UVA exposure, synergistically increase production of superoxide and 1 O 2 . 12-16…”

GSTM1-null and GSTA1-low activity genotypes are associated with enhanced oxidative damage in bladder cancer

“…20,21 In particular, the formation of DNA adducts due to increased ROS generation during the conversion of PAHs to quinones is well documented. 22 It can be assumed that during malignant transformation a significant perturbation of cellular redox status occurs, which can result in ROS-mediated DNA damage, gene mutations and structural alterations to the DNA. Moreover, it is important to note that oxidative stress interacts not only with initiation, but also with the promotion and progression of cancer.…”