A Study On The Apoptosis, Proliferation And Its Correlative Regulators In Human Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most frequent human malignancies worldwide, and its mechanism is rather complicated. Previous studies have shown the association between hepatocellular carcinogenesis and the mutation of oncogene, inactivation of tumor suppressor genes. Recently, it found that there are cellular proliferation and apoptosis (programmed cell death), which are seemingly the opposite processes, in hepatocellular carcinoma, and it is relation to hepatocarciogenesis and progression. But the mechanism of proliferation,apoptosis,and its relationship, in the carcinogenesis of HCC remain unclear, p16 gene plays an important role in the HCC development, and deletion, mutation and methylation of p1 6 gene are usually found in HCC. But its role in the genesis and progression of HCC need to be elucidated. The expression of P53, P16, Fas protein and p16 methylation in the specimens of HCC from 35 patients and their corresponding noncancerous tissues were detected by the TUNEL, immunohistochemistry, and PCR. Meanwhile, in order to explore the role of apoptosis, expression of PCNA, P53, Fas, P16 protein and p16 CpG methylation in carcinogenesis and progression of HCC, we attempt to provide useful approaches to therapy. The main results are as follows:1. It was found that the index of apoptotic cells that scattered within HCC tissue was significantly lower than that in correspondent tumor-adjacent tissue. However, the index of PCNA was much higher in HCC than that in correspondent tumor-adjacent tissue. It suggested that the imbalance ofproliferation and apoptosis lead to the formation of HCC.2. Importantly, the apoptotic index at pathological stage and clinical phase. I , II, III and IV of HCCs decreased gradually. On the contrarily, the indexof PCNA increased in the same specimen. These findings suggest that the tumor differentiation is directly proportional to the apoptotic index and is inversely proportional to the index of PCNA in HCC.3. Fas, P53 protein expression were positive in the tumors and their neighboring regions and related to the pathological stage and clinical phase. There was a greater tendency to be reflected that the rates of P53 expression increase in HCC with advanced Edmondson stages. In HCC with P53 positively expression, the ratio of apoptosis declined markedly with the increase expression of PCNA-LI, it showed that the overexpression of P53 contribute to the proliferation of HCC and abrogate the its apoptosis. However, in HCC with Fas expression, the ratio of apoptosis increased significantly and PCNA-LI remained, it means that the apoptosis could be promoted by the overexpression of Fas.4. Methylation of p16 gene were found in 11/35 (31.43%)samples obtained from the metastatic tumors, no methylation of p16 gene were detected in all the tumor-adjacent tissues. However, methylation of p16 was major found in the HCC with P16 protein negative. Meanwhile, in HCC with P16 protein positive, methylation of p1 6 were not detected. These findings suggest that methylation of p16 gene may be one of the main mechanism of the inactivation of p16 gene, p16 methylation may play an important role in the early genesis of HCC.5. It was found that the protein expression of P16 of tumor tissues was much lower than that of tumor-adjacent tissues and related to the pathological stage and clinical phase. It is suggested that P16 protein play an important role in the progression of HCC.