title: γH2AX, pChk1, and Wip1 as potential markers of persistent DNA damage derived from dibenzo[a,l]pyrene and PAH-containing extracts from contaminated soils.
abstract: Polycyclic aromatic hydrocarbons (PAHs) are formed during incomplete combustion of organic material and are ubiquitous environmental contaminants. High levels of PAHs are commonly found in soils at industrial sites, thereby constituting a risk for humans and the environment. However, this risk is often difficult to estimate due to the complexity of the contamination. In the present study, we investigated the cellular DNA damage response induced by extracts of PAH-contaminated soils collected at various industrial sites in Sweden. The results show that interactions of PAHs in the soil extracts caused activation of DNA damage signaling consistent with persistent DNA damage. Signaling in HepG2 cells exposed to soil PAH extracts corresponding to 1 μM benzo[a]pyrene was similar to that of 0.1 μM dibenzo[a,l]pyrene, a highly carcinogenic PAH known to produce persistent DNA damage. The response involved prolonged activation of DNA damage marker (H2AX), check point kinase (Chk1), and phosphatases (Wip1). Furthermore, blocking DNA damage signaling using specific inhibitors and siRNA showed the important role of signaling through Chk1 for the level of DNA damage. We conclude that the combination of prolonged Chk1 phosphorylation and induced expression of Wip1 might serve as potential markers for persistent DNA damage induced by complex mixtures of environmental PAHs. Discrepancies between mRNA and protein levels of Wip1 in response to soil extracts, in parallel with increased microRNA (miR)-16 levels, suggest a role of miR-16 in the regulation of DNA damage signaling in response to PAHs. Taken together, our data indicate that PAH extracts induce irreparable DNA damage and that this is consistent with the prolonged activation of DNA damage signaling.
authors.affiliation: Institute of Environmental Medicine, Karolinska Institutet, S-171 77 Stockholm, Sweden.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Niziolek-Kierecka
authors.forename: Kristian
authors.initials: K
authors.lastname: Dreij
authors.forename: Staffan
authors.initials: S
authors.lastname: Lundstedt
authors.forename: Ulla
authors.initials: U
authors.lastname: Stenius
mesh_terms: D001564:Benzo(a)pyrene / Q000737:chemistry / Q000633:toxicity*; D015415:Biomarkers / Q000378:metabolism; D000071877:Checkpoint Kinase 1; D004249:DNA Damage / Q000187:drug effects*; D056945:Hep G2 Cells; D006657:Histones / Q000378:metabolism*; D006801:Humans; D035683:MicroRNAs / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010766:Phosphorylation; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry / Q000633:toxicity*; D011494:Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000071636:Protein Phosphatase 2C; D034622:RNA Interference; D034741:RNA, Small Interfering; D012989:Soil Pollutants / Q000737:chemistry / Q000633:toxicity*
chemical_list: D015415:Biomarkers; C468783:H2AX protein, human; D006657:Histones; C505362:MIRN16 microRNA, human; D035683:MicroRNAs; D011084:Polycyclic Aromatic Hydrocarbons; D034741:RNA, Small Interfering; D012989:Soil Pollutants; D001564:Benzo(a)pyrene; D011494:Protein Kinases; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; C000607458:PPM1D protein, human; D010749:Phosphoprotein Phosphatases; D000071636:Protein Phosphatase 2C