Immunohistochemical Investigation of Migration Inhibitory Factor-related Protein (MRP)-14 Expression in Hepatocellular Carcinoma

Migration inhibitory factor-related protein (MRP)-8 and -14 belong to the S-100 protein family and are associated with myeloid cell differentiation. MRP is also expressed in some epithelia. However, there are few reports for the investigation on carcinomas. Using the monoclonal antibody 60B8 against MRP-14, we carried out the immunohistochemical evalution of MRP-14 expression in 70 cases of hepatocellular carcinoma (HCC), and examined the relation to tumor differentiation and vascular invasion. Positively stained tumor cells were detected in 32 cases, all of which belonged to grade II (7/30) or grade III (25/25) of the Edmondson-Steiner classification. In particular, the grade III HCC showed a significantly greater positive reaction. Immunopositivity in the non-carcinomatous hepatocytes and bile duct epithelia was not observed. These findings suggested that malignant hepatocytes newly express MRP-14 and that the neo-expression in differentiated HCC is related to the tumor differentiation and shows higher correlation in the poorly differentiated carcinomas. Furthermore, the cholangiocellular carcinoma and metastatic adenocarcinoma as control materials also presented a more marked immunoreactivity for MRP-14 in the poorly differentiated carcinomas, in a similar manner with the findings of the HCC. Accordingly, MRP is considered to be frequently neo-expressed in poorly differentiated carcinomas. MRP-14 expression rate in the 48 HCC cases with vascular invasion was 56%, showing no significant difference compared with non-invasive tumors.