人类肝癌发生过程中cyclinD1和CDK4及p16蛋白的表达

目的研究肝细胞癌(HCC)发生过程中细胞周期调控因子cyclinD1、CDK4和p16蛋白表达及其意义。方法应用免疫组织化学SP染色法检测正常肝组织、慢性肝炎、肝硬化、癌周肝硬化和肝癌组织中cyclinD1、CDK4和p16蛋白表达。对免疫组化结果进行计算机图象定量分析。结果cyclinD1、CDK4和p16蛋白的阳性单位(positive unit,PU)和面数密度(area number density,NA)从慢性肝炎(PU分别为39.4、41.0和33.3;NA分别为236.7、272.7和237.4)、肝硬化(PU分别为40.8、45.2和43.6;NA分别为313.8、354.6和322.9)、癌周肝硬化(PU分别为55.5、59.4和54.4;NA分别为481.9、488.9和432.6)到肝癌(PU分别为59.6、63.7和58.1;NA分别为549.2、587.7和451.3)表达逐渐增强。癌周肝硬化和肝癌组织中cyclinD1、CDK4、p16的表达明显高于慢性肝炎和肝硬化(P值分别为0.034、0.020、0.030、0.007、0.003和0.005),但癌周肝硬化和肝癌组织之间差异无统计学意义,P值分别为0.433、0.535和0.447。慢性肝炎和肝硬化中cy-clinD1、CDK4、p16阳性信号主要定位于胞核,而癌周肝硬化和HCC中主要定位于胞质。p16与HCC的分化程度有关,但未发现cyclinD1、CDK4与肿瘤分化程度之间有相关性。结论cyclin-细胞周期蛋白依赖性激酶(CDKs)-细胞周期蛋白依赖性激酶抑制因子(CKIs)调控网络中,相关调控因子的异常可能参与了HCC的发生、发展。cyclinD1、CDK4的过度表达可能是肝癌发生过程中的早期事件。在HCC的发生过程中p16高表达可能是细胞周期正反馈调控的结果,在HCC的发生中可能属于早期事件,而p16表达下降或缺失可能是肝癌发生过程中的晚期事件。

Expressions of cyclinD1,CDK4 and p16 in human hepatocarcinogenesis

OBJECTIVE: To evaluate the expressions and the significance of cyclinD1,CDK4 and p16 in hepatocellular carcinogenesis. METHODS: cyclinD1,CDK4 and p16 proteins were detected by S-P immunohistochemical staining in the total of 107 samples of chronic hepatitis, liver cirrhosis, paratumor cirrhosis, hepatocellular carcinoma (HCC) and normal liver tissues. Positive cases were quantitatively analysed by HPIAS-1000 Image Analysis System. RESULTS: The positive unit (PU) and area number density (NA) of positive cells of cyclinD1, CDK4 and p16 from chronic hepatitis (PU=39.4,41.0 and 33.3; NA=236.7,272.7 and 237.4), liver cirrhosis (PU=40.8,45.2 and 43.6; NA=313.8, 354.6 and 322.9), paratumor cirrhosis (PU=55.5, 59.4 and 54.4; NA=481.9, 488.9 and 432.6) to hepatocellular carcinoma (PU=59.6,63.7 and 58.1; NA=549.2, 587.7 and 451.3) were gradually increased. The protein levels of CyclinD1,CDK4 and p16 were higher in paratumor cirrhosis and HCC than those in chronic hepatitis and liver cirrhosis, P=0.034,0.020,0.030,0.007,0.003 and 0.005, whereas there was no significant difference between the expressions in paratumor cirrhosis and in HCC. In addition, there were cytoplasmic staining patterns of cyclinD1, CDK4, p16 positive cell in paratumor cirrhosis and HCC, while nuclear staining patterns in chronic hepatitis and liver cirrhosis. The poor differentiation of HCC was related to the lower expressions of p16. CONCLUSIONS: Alterations of cyclinD1,CDK4 and p16 may be involved in the occurrence and development of HCC.The overexpressions of cyclinD1 and CDK4 appear to be important events in early-stage of hepatocarcinogenesis. The high-level expression of p16 may be resulted from positive feedback regulation of cell cycle, which should be a molecular event in early phase of hepatocarcinogenesis, while reduce or loss of p16 may be a late-stage event.