Characterization of liver injury, oval cell proliferation and cholangiocarcinogenesis in glutathione S-transferase A3 knockout mice.

We recently generated glutathione S-transferase (GST) A3 knockout (KO) mice as a novel model to study the risk factors for liver cancer. GSTA3 KO mice are sensitive to the acute cytotoxic and genotoxic effects of aflatoxin B1 (AFB1), confirming the crucial role of GSTA3 in resistance to AFB1. We now report histopathological changes, tumor formation, biochemical changes and gender response following AFB1 treatment as well as the contribution of oxidative stress. Using a protocol of weekly 0.5 mg AFB1/kg administration, we observed extensive oval (liver stem) cell (OC) proliferation within 1-3 weeks followed by microvesicular lipidosis, megahepatocytes, nuclear inclusions, cholangiomas and small nodules. Male and female GSTA3 KO mice treated with 12 and 24 weekly AFB1 injections followed by a rest period of 12 and 6 months, respectively, all had grossly distorted livers with macro- and microscopic cysts, hepatocellular nodules, cholangiomas and cholangiocarcinomas and OC proliferation. We postulate that the prolonged AFB1 treatment leads to inhibition of hepatocyte proliferation, which is compensated by OC proliferation and eventually formation of cholangiocarcinoma (CCA). At low-dose AFB1, male KO mice showed less extensive acute liver injury, OC proliferation and AFB1-DNA adducts than female KO mice. There were no significant compensatory changes in KO mice GST subunits, GST enzymatic activity, epoxide hydrolase, or CYP1A2 and CYP3A11 levels. Finally, there was a modest increase in F2-isoprostane and isofuran in KO mice that confirmed putative GSTA3 hydroperoxidase activity in vivo for the first time.

F(2)-Dihomo-isoprostanes and brain white matter damage in stage 1 Rett syndrome.

Oxidative damage has been reported in Rett syndrome (RTT), a pervasive development disorder mainly caused up to 95% of cases by mutations in the X-linked methyl-CpG binding protein 2 (MeCP2) gene. We have recently synthesized F(2)-Dihomo-isoprostanes (F(2)-Dihomo-IsoP), peroxidation products from adrenic acid (C22:4 n - 6, AdA), a known component of myelin, and tested the potential value of F(2)-Dihomo-IsoPs as a novel disease marker and its relationship with clinical presentation, and disease progression. F(2)-Dihomo-IsoPs were determined by a gas chromatography/negative ion chemical ionization tandem mass spectrometry. The ent-7(RS)-F(2t)-Dihomo-IsoP and 17-F(2t)-Dihomo-IsoP were used as reference standards. The measured ions were the product ions at m/z 327 derived from the [M - 181](-) precursor ions (m/z 597) produced from both the derivatized ent-7(RS)-F(2t)-Dihomo-IsoP and 17-F(2t)-Dihomo-IsoP. Average plasma F(2)-Dihomo-IsoP levels in RTT were about 1 order of magnitude higher than in healthy controls, being higher in typical RTT as compared to RTT variants, with a remarkable increase of about 2 orders of magnitude in patients at the earliest stage of the disease followed by a steady decrease during the natural clinical progression. These data indicate for the first time that quantification of F(2)-Dihomo-IsoPs in plasma represents an early marker of the disease and may provide a better understanding of the pathogenic mechanisms behind the neurological regression in patients with RTT.