Immunocytochemical investigation of catalase and peroxisomal lipid beta-oxidation enzymes in human hepatocellular tumors and liver cirrhosis

A significant reduction of catalase activity, a peroxisomal. marker enzyme, occurs in human hepatic neoplasias, but no information is available on oth er peroxisomal proteins. We have studied by means of immunohistochemistry f our specific proteins of peroxisomes (catalase and three enzymes of lipid b eta-oxidation) in human hepatocellular tumors of various differentiation gr ades from adenoma to anaplastic carcinoma. In all tumors, except the adenom as, the tumor cells contained fewer peroxisomes than extrafocal hepatocytes and the reduction of antigenic sites in the tumor types generally correlat ed with the degree of tumor dedifferentiation as assessed by classical hist opathological criteria. Two poorly differentiated tumors had no detectable peroxisomes at all. There were no major differences in the intensities of t he immunocytochemical staining for all four studied peroxisomal antigens in different tumors, suggesting that the neoplastic transformation affects th e biogenesis of the entire organelle and not merely the individual peroxiso mal enzyme proteins. Some tumors exhibited a distinct peripheral distributi on of peroxisomes. In cases with associated liver cirrhosis, the hepatocyte s in the adjacent liver showed marked peroxisome proliferation, forming lar ge perinuclear aggregate, occupying occasionally the entire cytoplasm. Take n together, our observations indicate that peroxisomes are significantly al tered in both hepatocellular tumors and liver cirrhosis and, thus, could be responsible for some of the metabolic derangements observed in those disea se processes.