Human chorionic gonadotropin and alpha-fetoprotein in cholangiocarcinoma in relation to the expression of ras p21: an immunohistochemical study

Abstract

The immunohistochemical localization of human chorionic gonadotropin (HCG) and alpha-fetoprotein (AFP) was studied in 44 cases with cholangiocarcinoma (CC) to determine the correlation to the expression of ras oncogene product p21 on tumor cells. HCG-immunoreactivity was found in 10 of 44 cases (23%) and AFP in only one (2.3%), whereas the expression of ras p21 was demonstrated in 39 (88.6%). The incidence of HCG-positive cells within the tumor was less than 1% in 8 of 10. The incidence of AFP-positive cells was less than 0.01%. All were histologically classified as adenocarcinoma and none of them had histologic features of trophoblastic tumors, yolk sac tumor or hepatocellular carcinoma. Nine of 10 HCG-positive and one AFP-positive CC expressed ras p21 on their tumor cells. However, one HCG-positive CC was negative for ras p21, though the incidence of HCG-positive cells within the tumor was 25%. HCG- and AFP-immunoreactivity was more frequently observed in poorly or undifferentiated tumor cells than in moderately or well-differentiated areas, whereas the expression of ras p21 was more diffuse in well-differentiated tumor and stronger in moderately differentiated areas, but rarely found in poorly and undifferentiated tumor. These results suggest that HCG production by CC of the usual adenocarcinoma variety is not rare, when compared to AFP production, and is preferentially localized in a small number of poorly differentiated and undifferentiated carcinoma cells, and there is no correlation between the production of HCG or AFP and the expression of ras p21 in CCs.