Comparison of oxidative stress response parameters in newborn mouse liver versus simian virus 40 (SV40)-transformed hepatocyte cell lines

Induction of approximately one dozen genes and/or enzyme activities in live r of the untreated newborn c(14CoS)/c(14CoS) mouse-when compared with the c (ch)/c(14CoS) heterozygote or the c(ch)/c(ch) wild-type-is the result of en hanced levels of reactive oxygenated metabolites originating from a block i n the tyrosine degradation pathway. Oxidative stress activates genes via th e electrophile response element, whereas dioxin activates genes via the rec eptor-mediated aromatic hydrocarbon response element. Here, we compared sev eral parameters in 14CoS/14CoS Versus ch/ch newborn mouse liver with that i n simian virus 40 (SV40)-transformed hepatocyte lines that had been derived from newborn liver. We showed in this study that: (a) NADP(H):quinone oxid oreductase and UDP glucuronosyltransferase 1A6 mRNA levels were increased i n both the (untreated) 14CoS/14CoS newborn liver and cell line; (b) aldehyd e dehydrogenase 3A1 mRNA was increased by both oxidative stress and dioxin in hepatocyte cultures, but was not detectable in liver of the intact mouse ; (c) the glutathione S-transferase GSTA1, GSTP1, GSTA3, and GSTM1 mRNA lev els were increased by oxidative stress in 14CoS/14CoS newborn liver, but th ese transcripts were either low or undetectable in the cell lines; (d) GSTA 1 mRNA was up-regulated by the absence of cytochrome P450 1A1 (CYP1A1) acti vity (i.e. the Gsta1 gene is a member of the aromatic hydrocarbon [Ah] batt ery); and (e) GSTP1 mRNA was not up-regulated by the absence of CYP1A1 acti vity (i.e. Gstp1 is npt a member of the [Ah] battery). The 14CoS/14CoS and ch/ch hepatocyte established cell lines were transformed with SV40, which e xpresses large T antigen; this gene product is known to bind to, and intera ct with, several cell cycle regulatory proteins such as p53 and the retinob lastoma protein-E2F complex. It is therefore likely that differences in the oxidative stress responses between the 14CoS/14CoS newborn liver and the i mmortalized hepatocyte cell line might be explained by the presence of larg e T antigen in the established cell line. (C) 2000 Elsevier Science Inc.