EXPRESSION AND FUNCTIONS OF GROWTH-FACTORS AND GROWTH-FACTOR RECEPTORS IN LIVER-CANCER

Growth factors and growth factor receptors are known to play an import ant role in the regulation of cell proliferation and differentiation. It has been reported that some growth factors, such as HGF, EGF, TGF-b eta, insulin, IGF-I, and IGF-II, are hepatic mitogens, In recent years , it has been found that the regulation of the proliferation and diffe rentiation of liver tumor cells is associated with the expression and functions of HGF, EGF, TGF-alpha, insulin family, TGF-beta, and their receptors, It is known that HGF inhibits the growth of human hepatocel lular carcinoma HepG2 cells, HGF, HGF receptor, and their mRNAs are ex pressed more in hepatocellular carcinoma (HCC) than in normal liver, T GF-alpha is overexpressed in both hepatoma and adjacent non-tumorous l iver, The expression of EGF receptor in liver cancer cells appears mor e complex, In the Buffalo rats, normal liver cells have a high level o f functional EGF receptor, whereas, its hepatoma cells lack the recept or, In human cell lines, both Chang liver and HepG2 cells have a high level of EGF receptor, The expression of IGF-I receptor is increased i n HCC and in the hepatocytes of regenerating and fetal livers, IGF-II is expressed in some HCC and regulates tissue-specific gene expression in hepatoma cells, The urinary and plasma levels of TGF-beta 1 in pat ients with HCC are higher than those in patients with chronic hepatiti s and cirrhosis, The expression of albumin and AFP in hepatoma cells i s inhibited by TGF-beta.