Cellular vitamin A-binding proteins in liver tumors and adjacent tissues

The levels of cellular retinol-binding protein (CRBP) and retinoic acid-binding protein (CRABP) were assessed in surgically resected ten human liver tumors and their adjacent tissues by sucrose density gradient centrifugation and Scatchard analysis. The tissues adjacent to hepatocellular carcinomas usually showed portal cirrhosis or hepatitis. There was no significant difference in the dissociation constant (Kd) values of binding proteins of CRBP or CRABP between tumors and adjacent tissues. Five of the ten liver tumors showed similar levels of CRBP as in their adjacent tissues whereas three of the ten liver tumors showed about 40% or less contents of CRBP in comparison with their adjacent tissues and two others had no CRBP activity. By contrast, CRABP activities were found in five liver tumors and in adjacent tissues of one case, whereas there were no detectable CRABP activities in the adjacent tissues except in one case.