三氯乙烯慢性暴露致B6C3(F1代)小鼠肝癌伴肝组织组蛋白H2AK9乙酰化与SET上调

Induction of hepatocellular carcinoma in B6C3(F1)mice chronicly exposed to trichloroethylene with enhanced acetylation of histone H2AK9ac and SET expression in the liver tissue

目的建立三氯乙烯(TCE)慢性暴露诱导B6C3(F1代)小鼠肝癌动物模型,探讨肝组织中SET-CAN融合蛋白(SET)、乙酰化组蛋白H2AK9和组蛋白去乙酰化酶1(HDAC1)表达水平的改变,为TCE致肝癌的分子机制研究提供初步的线索。方法以B6C3小鼠的F1代子鼠为受试对象,用500、1000和2000 mg/kg TCE对6周龄小鼠进行灌胃染毒,同时设置玉米油溶剂对照组和四氯化碳(CCI4,1250 mg/kg)阳性对照组。染毒56周后取小鼠血清、肝脏进行生化指标检测和病理学鉴定,并用蛋白免疫印迹法(Western blot)检测SET、H2AK9乙酰化及HDAC1的水平。结果小鼠的存活率为90.4%(141/156),各组之间差异无统计学意义(P>0.05)。与溶剂对照组比较,各TCE剂量组和阳性对照组中谷丙转氨酶(ALT)、谷草转氨酶(AST)、乳酸脱氢酶(LDH)活性及血尿素氮(BUN)水平升高,差异均有统计学意义(P<0.01);中、高TCE剂量组肌酐(CREA)水平升高(P<0.05),各TCE剂量组患癌率及ALT、AST活性呈剂量依赖性升高(P<0.01),中、高ECT剂量组SET、H2AK9ac水平升高,HDAC1表达降低,差异均有统计学意义(P<0.05)。与肝脏癌旁组织比较,中、高TCE剂量组癌组织中SET表达升高、HDAC1降低,高剂量组中H2AK9乙酰化水平升高,差异均有统计学意义(P<0.05)。结论本次研究建立TCE致B6C3F1代小鼠肝癌模型,伴随肝组织的组蛋白H2AK9乙酰化水平升高和SET上调。

Objective To establish an animal model of trichloroethylene(TCE)-induced liver cancer following chronic exposure and to understand the changes in SET expression and histone acetylation,potentially serving as a molecular mechanism for TCE-induced hepatocarcinogenesis.Methods B6C3 mice at 6 weeks were treated with TCE at a series of doses(500,1000 and 2000 mg/kg)by gastric gavage,with corn oil used as the negative control and carbon tetrachloride(CCl4)as the positive control.The serum and liver were sampled for the determination of biochemical indexes and pathological examination after 56 weeks of chemical exposure.Western blot was used to determine the levels of SET,H2AK9ac and HDAC1 expression.Results The overall survival rate of the mice in various groups was 90.4%(141/156),with no statistical difference between groups(P>0.05).Compared with the negative control,the organ coefficient for the liver in the high dose TCE group and the positive control group were significantly increased(P<0.05).The levels of ALT,AST,LDH and BUN in the all the three TCE groups and the positive control were significantly higher than those in the negative control(P<0.01).CREA levels in the 1000 and 2000 mg/kg TCE groups were significantly higher than those in the negative control(P<0.05).Statistical increases in the incidence of hepatocellular carcinoma and the activities of ALT and AST in various doses of TCE-exposed mice as compared with the control were observed(P<0.01),in a dose-dependent manner.In the 1000 and 2000 mg/kg of TCE treated mice,levels of SET and H2AK9ac were increased(P<0.05),while HDAC1 was decreased(P<0.05),Compared to the tissue adjacent to liver cancer,in the 1000 and 2000 mg/kg TCE groups,the levels of SET were increased(P<0.05),while HDAC1 was decreased(P<0.05),and H2AK9ac increased in the 2000 mg/kg group.Conclusion The hepatocellular carcinoma mouse model induced by chronic exposure to trichloroethylene was successfully established,with enhanced SET protein expression and H2AK9ac in the hepatic tissue.