Changes and significance of metallothionein expression during hepatocarcinogenesis in C57BL/6J mice / 中国比较医学杂志

ABSTRACT

Objective To investigate the dynamic changes of metallothionein(MTs)gene expression and explore the important significance of MTs during hepatocarcinogenesis.Methods One hundred and twenty-five SPF 5 -8-week old male C57BL/6J mice were randomly divided into control group and model group.Diethylnitrosamine (DEN) was given to the mice at a dose of 100 mg/kg, ip, and 50 mg/kg, ip, in the first and next week, respectively.The mice were given ethanol (53%, 5 mL/kg/day, 5 days/week) from the third week of experiment till 35 weeks.At 1, 3, 9, 13, 24 and 35 weeks of the experiment, liver samples were taken for histopathological examination of liver damages and incidence of HCC. The liver index and malondialdehyde (MDA) of liver homogenate were determined.All liver tissue samples were examined by histopathology using hematoxylin and eosin (HE), Masson and reticular fiber staining.Real-time RT-PCR was used to analyze the mRNA expression level of liver metallothionein-1 /2 (MT-1 /2) in different periods.Results Progressive liver damages in model group mice were identified in different periods.Hepatocytes abnormal tission and abnormal liver plate structure, architecture often characteristic of HCC could be seen in approximately 50% of mice at 35 weeks.In addition to these, a higher liver index also were seen at 35 weeks.Increased MDA levels in the mouse liver tissues were observed in each stage.Real-time RT-PCR analysis showed that significantly increased transcription of MT-1 and MT-2 at 1, 3 and 9 weeks, then gradually declined and even below the normal level.Conclusions MTs gene expression levels in mouse liver tissues are changed from significantly increased in the early stage of injury to decreased expression combined with distinct fibrosis. Our findings further demonstrate that the down-regulation of MTs level is closely correlated with hepatocarcinogenesis.