title: Cytotoxicity and genotoxicity of phenazine in two human cell lines.
abstract: Phenazine was recently identified as a drinking water disinfection byproduct (DBP), but little is known of its toxic effects. We examined in vitro cytotoxicity and genotoxicity of phenazine (1.9-123 μM) in HepG2 and T24 cell lines. Cytotoxicity was determined by an impedance-based real-time cell analysis instrument. The BrdU (5-bromo-2'-deoxyuridine) proliferation and MTT ((3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) viability assays were used to examine mechanisms of cytotoxicity. Genotoxicity was determined using the alkaline comet assay. Concentration-dependent cytotoxicity was observed in HepG2 cells, primarily due to an antiproliferative effect (BrdU 24 h IC50: 11 μM; 48 h IC50: 7.8 μM) observed as low as 1.9 μM. T24 cells experienced a minor antiproliferative effect (BrdU 24 h IC50: 47 μM; 48 h IC50: 17 μM). IC50 values for HepG2 proliferation and viability were 54-77% lower compared to T24 cells. In both cell lines, IC50 values for proliferation were 66-90% lower than those for viability. At phenazine concentrations producing equivalent cytotoxicity, HepG2 cells (1.9-30.8 μM) experienced no significant genotoxic effects, while T24 cells (7.7-123 μM) experienced significant genotoxicity at ⩾61.5 μM. While these effects were seen at phenazine concentrations above those found in disinfected water, the persistence of the antiproliferative effect and the differential toxicity in each cell line deserves further study.
authors.affiliation: Division of Analytical & Environmental Toxicology, 10-102 Clinical Sciences Building, Department of Laboratory Medicine & Pathology, University of Alberta, Edmonton, Alberta T6G 2G3, Canada. Electronic address: mcguigan@ualberta.ca.
authors.forename: Claire F
authors.initials: CF
authors.lastname: McGuigan
authors.affiliation: Division of Analytical & Environmental Toxicology, 10-102 Clinical Sciences Building, Department of Laboratory Medicine & Pathology, University of Alberta, Edmonton, Alberta T6G 2G3, Canada. Electronic address: xingfang.li@ualberta.ca.
authors.forename: Xing-Fang
authors.initials: XF
authors.lastname: Li
mesh_terms: D001973:Bromodeoxyuridine; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004785:Environmental Pollutants / Q000737:chemistry / Q000633:toxicity*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D020128:Inhibitory Concentration 50; D010619:Phenazines / Q000737:chemistry / Q000633:toxicity*; D013997:Time Factors
chemical_list: D004785:Environmental Pollutants; D010619:Phenazines; C000598831:phenazine; D001973:Bromodeoxyuridine
keywords: Comet assay; Cytotoxicity; Drinking water disinfection byproducts; Genotoxicity; Phenazine; Real-time cell analysis