DEMONSTRATION OF A NOVEL CELLULAR RETINOL-BINDING PROTEIN, F-TYPE, IN HEPATOCELLULAR CARCINOMA

  • 1 January 1979
    • journal article
    • research article
    • Vol. 70  (2) , 215-222
Abstract
Vitamin A level and the cytosol-binding proteins specific for vitamin A were studied in human tumor and its surrounding tissue. The tissues examined were 10 hepatocellular carcinomas which were surgically removed, 4 other malignant tumors (2 metastatic liver cancer and 1 each of gastric cancer and glioma) and 3 human fetal livers. Compared with surrounding tissues, considerable decrease of vitamin A content was observed in the hepatocellular carcinoma, suggesting local deficient state of the vitamin. In addition to cellular retinol-binding protein (CRBP) and retinoic acid-binding protein (CRABP), a new molecular species having affinity for both retinol and retinoic acid was detected in the cytosols obtained from hepatocellular carcinoma and glioma by gel filtration on Sephadex G-75. With regard to ligand specificity, the protein was similar to cellular retinol-binding protein, F-type or CRBP(F) which was originally recognized in the fish eye cytosol. Since the protein was also demonstrated in human fetal liver, CRBP(F) is considered as oncofetal protein in nature. CRBP(F) was detected in 80% of hepatocellular carcinoma (whereas plasma .alpha.-fetoprotein was significantly elevated only in 50%), and hepatocellular carcinoma contained CRBP(F) in a larger amount than CRABP.