Expression of cell adhesion molecule CD44 in primary tumors of the liver: an immunohistochemical study
CD44, a widely distributed integral membrane protein, has been implicated in tumor invasion and metastatic spread in some human carcinomas and lymphomas. In this study, 35 cases of hepatocellular carcinoma from 32 patients (11 cholangiocarcinomas, 9 hepatic adenomas, and 5 cases of focal nodular hyperplasia, a non-neoplastic lesion) were examined by immunohistochemical methods for expression of CD44. The mouse monoclonal antibody A3D8 was used on formalin-fixed, paraffin-embedded tissue; this antibody does not distinguish between standard CD44 and splice variants. Positive membrane staining was seen in 13 of 35 cases of hepatocellular carcinoma (12 of 32 patients), 8 of 11 cases of cholangiocarcinoma, and 1 of 9 cases of hepatic adenoma. The strongest staining for CD44 was seen in two cases of fibrolamellar carcinoma, but CD44 expression was otherwise not related to degree of tumor differentiation. All five cases of focal nodular hyperplasia were negative for CD44. In non-neoplastic liver, hepatocytes were negative; sinusoidal lining cells and portal lymphocytes were positive; bile ducts and proliferating bile ductules were focally positive in some cases. Anatomic stage at time of presentation was similar in both groups of patients, with most patients presenting with stage III or IV disease. A trend towards slightly longer survival in patients whose hepatocellular carcinomas were CD44 negative was noted. These results show that aberrant CD44 expression is present in a subset of hepatocellular carcinomas and in most cholangio-carcinomas. The relationship between CD44 expression and tumor spread is unclear in this group of tumors, but is unlikely to be a simple association between CD44 expression and metastatic potential.