Biological Significance Of Centromere Protein A In Primary Hepatocellular Carcinoma

To disclose biological function and genetic mechanisms in hepatocellular carcinoma (HCC) with a view toward development of novel therapeutic targets, we analyzed expression of centromere protein A (CENP-A) up-regulated by mutant of HBx in HCC tissues . By conventional and real time RT-PCR, western blotting , immunohistochemical staining (IHC) and PCR-SSCP, mRNA and protein levels of CENP-A were measured in HCC tissues as well as the mutation in CENP-A DNA. The results showed that CENP-A was highly expressed in tumor tissues compared to noncancerous liver tissues. The protein expression of CENP-A in the HCC was paralleled with the mRNA expression level. A significantly higher tumor CENP-A over-expression level was associated with the increased expression of p53 protein and the progression of histological grades. We also found that the over-expression of CENP-A was related to transcriptional regulation , instead of the mutation in genomic DNA. In additionally, RNA interference technique and sense CENP-A gene transfection method were employed to observe the biological behaviors of CENP-A in transfected HCC cell (HepG2). The results demonstrated that transfected cells with CENP-A siRNA were inhibited on growth and increased on apoptosis. In the cell cycles, phase of G1 was delayed and cell numbers in phase of S were decreased. In the cells in which CENP-A was knock-downed, the mRNA level of Bcl-2 was significantly decreased, whereas that of Bax was significantly increased. In the cells in which CENP-A was over-expressed, growth was promoted and the cloning efficiency was enhanced. All of these results demonstrated that CENP-A expression were involved in malignant cell proliferation in HCC. The interaction between CENP-A and p53 was also preliminarily investigated in vitro by gene transfection techniques, which would be benefit to make clear the biological function of CENP-A and its mechanism in HCC.