Normal Human Liver And Human Hepatoma Cells, N-ras Gene Expression Regulation

Due to the rapid progress of molecular biology, studies on the mechanisms of carcinogenesis have reached a higher level. Recently, results have acumulated indicating that the products of cellular oncogenes are closelyrelatedto cell proliferation,cell differentia-tion and carcinogenesis. The fact that cellular oncogenes are highly preserved in the process of evolution indicates that they are the important components which are essential for normal cell growth. It has been demonstrated that the products of cellular oncogenes participate in the regulation of normal cell growth at diferent levels. Some of them are growth factors; some are receptors for growth factors; some participate in the transduction process of growth imformation from cellmembrane to nucleus. Furthermore, some of them themselves are the DNA-binding proteins which regulate gene expression directly in the nuclei.The expression of cellular oncogene, as other cellular genes, is controlled by a series of regulation mechanisms. Cellular oncogenes may induce neoplasia only if they are activated by mutations in the coding sequences or they expressed at an abnormal level. Therefore, studies on the regulation mechanisms of cellular oncogenes in the normal and tumor cells are very important for us to have a deeper understanding of the mechanisms of carcinogenesis...