Differential expression of metallopanstimulin/S27 ribosomal protein in hepatic regeneration and neoplasia

We have previously shown that human metallopanstimulin-1 (MPS-1) is a ubiqu itous 9.4-kd multifunctional ribosomal S27/nuclear "zinc finger" protein th at is expressed at high levels in a wide variety of actively proliferating cells and tumor tissues. In this study, we examined the expression of MPS-1 in chronic hepatitis, cirrhosis, and hepatocellular carcinoma. Tissue samp les were obtained at the time of tumor resection, needle biopsy, or liver t ransplantation. MPS-1 was studied by immunohistochemistry by use of specifi c antibodies to the N-terminus of MPS-1 in a biotin/streptavidin-amplified system. In chronic hepatitis, hepatocytes had very weak MPS-1 immunostainin g. In contrast, hepatocytes in regenerating cirrhotic nodules stained stron gly for MPS-1. In well-differentiated hepatocellular carcinoma, MPS-1 prese nce was intense at the periphery of the malignant. nodule. In poorly differ entiated hepatocellular carcinoma, MPS-1 presence was notably intense in ma lignant hepatocytes invading the septal tissues, in close contact with neov ascular structures. These results suggest that MPS-1 may be involved in bot h progression toward malignancy in regenerating cirrhotic nodules and in su bsequent steps of hepatocarcinogenesis.