Jeong D H, Jang J J, Lee S J, Lee J H, Lim I K, Lee M J, Lee Y S
College of Veterinary Medicine Kyungpook National University, Daegue, Korea.
J Gastroenterol. 2001 Jan;36(1):24-32. doi: 10.1007/s005350170150.
To analyze the aberrant expression of cell cycle-related proteins and their biological significance in relation to cirrhosis, we compared the cirrhotic patterns induced by two different types of cirrhotic agents, CCl4 and thioacetamide (TAA) in rats. CCl4 or TAA treatment was given to rats for 8 or 30 weeks, respectively, and the livers were removed at 9, 20, and 30 weeks after the experiment began. The TAA-induced fibrotic pattern was different from the CCl4-induced one, in terms of the formation of fibrous connective tissue and the proliferation of bile ductule cells. Cholangiofibrosis and clear cell foci were also observed in TAA-treated rats at 30 weeks. Histological examination revealed severe cirrhotic changes at 9 weeks in CCl4-treated rats and at 30 weeks in TAA-treated rats. Immunoblotting for cyclin D1, E, A, B, and proliferating cell nuclear antigen (PCNA) and their counterpart protein kinases (CDK2, 4, and CDC2) showed significant overexpression in rats with severely cirrhotic livers. The p53 tumor suppressor protein increased dramatically in the CCl4-treated group, while it was not detected in the livers of TAA-treated rats. Upregulation of p21WAF1, a CDK inhibitory protein, was detected in TAA-treated rats, but not in CCl4-treated rats. Immunohistochemical data for cyclin D1, E, and PCNA were well correlated with immunoblotting data; these proteins were increased in hepatocytes surrounding the cirrhotic lesions, suggesting that hepatocyte regeneration is correlated with cell cycle-related protein expression in cirrhotic liver. In the TAA-treated rats, the expression of these proteins was increased both in hepatocytes and in ductule cells. Our data suggest that liver cirrhosis induced by CCl4 or TAA is associated with alterations in cell cycle-related proteins, and that the expression of these proteins is responsible for hepatocyte regeneration in the damaged liver and may be involved in liver carcinogenesis.
为了分析细胞周期相关蛋白的异常表达及其与肝硬化相关的生物学意义，我们比较了两种不同类型的肝硬化诱导剂（四氯化碳（CCl4）和硫代乙酰胺（TAA））在大鼠中诱导的肝硬化模式。分别给大鼠进行8周或30周的CCl4或TAA处理，并在实验开始后的9周、20周和30周取出肝脏。就纤维结缔组织的形成和胆小管细胞的增殖而言，TAA诱导的纤维化模式与CCl4诱导的不同。在30周时，TAA处理的大鼠中也观察到胆管纤维化和透明细胞灶。组织学检查显示，CCl4处理的大鼠在9周时以及TAA处理的大鼠在30周时出现严重的肝硬化变化。对细胞周期蛋白D1、E、A、B和增殖细胞核抗原（PCNA）及其相应蛋白激酶（CDK2、4和CDC2）进行免疫印迹分析，结果显示在患有严重肝硬化肝脏的大鼠中显著过表达。p53肿瘤抑制蛋白在CCl4处理组中显著增加，而在TAA处理的大鼠肝脏中未检测到。在TAA处理的大鼠中检测到CDK抑制蛋白p21WAF1上调，而在CCl4处理的大鼠中未检测到。细胞周期蛋白D1、E和PCNA的免疫组化数据与免疫印迹数据高度相关；这些蛋白在肝硬化病变周围的肝细胞中增加，表明肝细胞再生与肝硬化肝脏中细胞周期相关蛋白的表达相关。在TAA处理的大鼠中，这些蛋白在肝细胞和胆小管细胞中均增加。我们的数据表明，CCl4或TAA诱导的肝硬化与细胞周期相关蛋白的改变有关，并且这些蛋白的表达负责受损肝脏中的肝细胞再生，可能参与肝癌发生。
