| Hepatocellular carcinoma (HCC) is the most common malignant tumor in the world, with an incidence of 1,000,000 new cases a year. Because of high morbility and mortality, it threaten the health of human.Background:Apoptotic events in hepatocytes can be regulated by different stimuli that bind to death receptors in the cell membrane, such as Fas ligand (FasL), tumor necrosis factor-alpha (TNF-α) and so on, which activate the extrinsic pathway. Furthermore, other factors, particularly the transforming growth factor-beta (TGF-β), do not bind to death receptors, but its intracellular signals couple to the apoptotic machinery through activation of the intrinsic pathway[4]. Indeed, insufficient apoptosis has been associated with development and progression of HCC.The CIDE(cell death-inducing DFF45-like effector) gene family is a new gene family which has been identified in recent years. Within the CIDEs family, three members, CIDE-A and CIDE-B and CIDE-3 in human and three members, Cide-a, Cide-B and Fsp27, have been identified in mouse. CIDEs contained an N-terminal region with homology to DFF(DNA fragmentation factor)45, there exists also a C-terminal conserved sequence important for their function of apoptosis.Based on the role of CIDEs in cellular events common to the processes of development and oncogenesis such as proliferation and apoptosis. In the previous study, we showed that the expression of CIDE-3 is different in HCC and adjacent normal tissue. The positive rates of human CIDE-3 protein in HCC decreased significantly in comparison with hepatic cells around HCC(P<0.05). And positive expression rates in the poorly differentiated HCC tissue was lowest, in the moderately differentiated HCC was lower lever whereas in the well differentiated HCC tissue, expression of human cide-3 protein in the well differentiated HCC tissue was strangest. But little is known of the relationship between HCC and CIDE-3.Objective:We initiated the current study to find weather CIDE-3 have an effect on the apoptosis of HCC cell and which one is the interact-protein with CIDE-3 in the hepatic cell. So we try to update the main molecular alterations reported for HCC that alter its apoptotic response. This study is significant to consummate etiology of HCC, to screen the novel molecular marker and to develop the targeted drug.Methods:1 Constructed recombinant vector pcDNA3.1-CIDE-3 containing CIDE-3 gene fragment, transfected SMMC-7721 by liposome. Test the apoptosis and proliferation of SMMC-7721. 2 Screen the human liver cDNA library with the prey protein CIDE-3 by yeast two-hybrid , to find the interacting-proteins of CIDE-3.Results:1 We Successfully constructed recombinant vector pcDNA3.1-CIDE-3 containing CIDE-3 gene fragment, transfected SMMC-7721 by liposome. We find that the overexpression of CIDE-3 can induce apoptosis and inhibit the growth of HCC cell line SMMC-7721 .2 We identified CIDE-3 as a LITAF (Homo sapiens lipopolysaccharide - induced TNF factor, also called p53 inducing gene 7, PIG7) -interacting protein in the liver by yeast two-hybrid screening . We showed that LITAF physically interacts with CIDE-3 in vitro and in vivo by immunocoprecipitation and mammal cell two-hybrid system; and 1~145aa is of CIDE-3 was necessary to its interaction with LITAF; this interaction leads to stronger apoptosis of HCC cells.Conclusions:To conclude, our research work indicated that:①Our data suggests that CIDE-3 takes part in the apoptosis of hepatoic cells and may therefore effect oncogenesis and development of HCC ;②Identification of the interaction of CIDE-3 and LITAF provided new thinking and research work direction for further CIDE-3 function investigation. |
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