Distribution of Ligandin in Normal and Azocarcinogen-Treated Rat Liver and Azocarcinogen-Induced Liver Tumors

Abstract

Antibodies were raised in rabbits against pure ligandin. Employing the fluorescent antibody procedure, an antigen identical to ligandin was shown to be uniformly distributed in the hepatic cells of both normal rat liver and in early and late 3′-methyl-4-dimethylaminoazobenzene (3′-Me-DAB)-treated liver. Ligandin was absent in liver carcinomas induced by this azocarcinogen. The results obtained with the fluorescent antibody procedure were confirmed by the immunoquantitation of ligandin in the cytosols prepared from normal rat liver, early and late 3′-Me-DAB-treated liver, mixtures of both late 3′-Me-DAB-treated liver and liver carcinomas, and liver carcinomas. Riboflavin-deficient diets lowered significantly the hepatic ligandin content.

Ligandin Content of Normal and Carcinogen-Treated Rat Tissues

“…Ligandin was determined in some normal and car cinogen-treated tissues by immunoquantitation [7]. Liver cytosol contained the largest amount of ligandin ( fig.…”

“…6-8 months old and weighing about 300 g were used. The carcinogens, 3'-methyl-p-dimethylaminoazobenzene Antisera were raised in rabbits against pure ligandin as previously described [7]. The carcinogens were dissolved in cotton seed oil (20 mg/ml) and administered by stomach tube to rats (20 mg/100 g) as was done previously [8], The 3'-Me-DAB-treated rats were sacrified after an overnight fast at 41 h after treatment when there is maximum incorporation of this carcinogen into liver proteins [8|.…”

Hepatocellular Ligandin during N-2-Fluorenylacetamide Carcinogenesis

“…Presence of ligandin in the nucleus [7,10] and receptor role of the carcinogen-binding proteins [15,16] suggest that ligandin may be involved in translocation of the carcinogen metabolites into the nucleus. Ligandin [6,7] and other azodye-binding proteins [8][9][10][11][12][13][14] are reduced or absent after azodye administration and in azodye-induced carcinomas. The levels of binding proteins in these azodye-induced hepatomas were determined immunologically, often in tissue homogenates [6][7][8][9][10][11][12][13][14].…”

“…Ligandin [6,7] and other azodye-binding proteins [8][9][10][11][12][13][14] are reduced or absent after azodye administration and in azodye-induced carcinomas. The levels of binding proteins in these azodye-induced hepatomas were determined immunologically, often in tissue homogenates [6][7][8][9][10][11][12][13][14].…”