Crawford Dana R, Ilic Zoran, Guest Ian, Milne Ginger L, Hayes John D, Sell Stewart
Albany Medical Center, Department of Immunology and Microbial Disease, 43 New Scotland Avenue, Albany, NY 12208, USA.
Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA.
Carcinogenesis. 2017 Jul 1;38(7):717-727. doi: 10.1093/carcin/bgx048.
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.
我们最近培育出了谷胱甘肽S-转移酶（GST）A3基因敲除（KO）小鼠，作为研究肝癌风险因素的新型模型。GSTA3基因敲除小鼠对黄曲霉毒素B1（AFB1）的急性细胞毒性和基因毒性作用敏感，这证实了GSTA3在抵抗AFB1方面的关键作用。我们现在报告AFB1处理后的组织病理学变化、肿瘤形成、生化变化和性别反应以及氧化应激的作用。使用每周0.5毫克AFB1/千克的给药方案，我们观察到在1至3周内有广泛的卵圆（肝干）细胞（OC）增殖，随后出现微泡性脂肪变性、巨肝细胞、核内包涵体、胆管瘤和小结节。雄性和雌性GSTA3基因敲除小鼠分别接受12周和24周的AFB1每周注射，随后分别休息12个月和6个月，所有小鼠的肝脏均严重变形，出现宏观和微观囊肿、肝细胞结节、胆管瘤和胆管癌以及OC增殖。我们推测，长期的AFB1处理会导致肝细胞增殖受到抑制，并由OC增殖进行代偿，最终形成胆管癌（CCA）。在低剂量AFB1处理下，雄性基因敲除小鼠的急性肝损伤、OC增殖和AFB1-DNA加合物比雌性基因敲除小鼠的程度要轻。基因敲除小鼠中的GST亚基、GST酶活性、环氧化物水解酶或CYP1A2和CYP3A11水平没有明显的代偿性变化。最后，基因敲除小鼠中F2-异前列腺素和异呋喃有适度增加，首次在体内证实了推测的GSTA3氢过氧化物酶活性。
