AMPLIFICATION OF BCR PROTEIN ASSOCIATED WITH ONCOGENESIS IN HUMAN HEPATOCELLULAR-CARCINOMA

The BCR gene is located on human chromosome 22. The normal cellular BC R gene encodes a 160,000-dalton phosphoprotein associated with a serin e/threonine kinase activity. The BCR protein is involved in signal tra nsduction. We investigated the expression of the BCR protein in hepato cellular carcinoma (HCC), surrounding noncancerous liver tissue, liver cirrhosis (LC), chronic hepatitis (CH), and normal liver with immunoh istochemistry and a western blot analysis. BCR immunoreactivity was de tected using a monoclonal antibody. In normal liver, and both CH and L C without association of HCC, the immunoreactivity of the BCR protein was minimal. In contrast, 73% (22 of 30) of noncancerous liver tissue adjacent to the HCC and 40% (12 of 30) of HCC expressed BCR protein; t his difference was statistically significant (P < 0.01). The expressio n of the BCR protein expression correlated with the degree of histolog ical differentiation of HCC (P < 0.05). In addition, the amplification of BCR protein in noncancerous cells was supported by the detection o f specific protein using a western blot analysis. In two cases, the ex pression of BCR protein occurred only in overtly malignant HCC cells. As a result, the expression of the BCR protein may be associated with oncogenesis in human HCC.