Structural and metabolic distinction between Morris Hepatoma 5123 A and normal rat liver

AbstractEvidence is presented to show that Morris Hepatoma 5123 A differs strikingly from homologous normal tissue in its metabolic and structural aspects.The succinoxidase activity of Hepatoma 5123 A is only 40% that of liver, while anaerobic glycolysis, although relatively low, is nevertheless some 100% higher than in normal liver. The mitochondrial content of Hepatoma 5123 A is about 40% that of the normal liver cell. The amount of material in the microsomal fraction is reduced in the hepatoma and there is a pronounced shift in the distribution of RNA in favor of the RNA in the nuclear and supernatant fractions. Hepatoma 5123 A shares all of these characteristics with other known tumors.In distinction to rapidly growing tumor and proliferating tissue, Hepatoma 5123 A has about the same or higher dCMP‐ase activity as normal liver, while dCMP‐deaminase is about 20 times as high as in normal rat liver.In addition to the quantitative depletion of mitochondria, Hepatoma 5123 A shows also a depletion in the flavin and cytochrome c content of the mitochondrial soluble matrix. In contrast to normal mitochondria, in which the administration of 3,3',5‐tri‐iodothyronine led to a an increase several times the normal value, in the activity of α‐glycerophosphate dehydrogenase, the level of this enzyme in tumor mitochondria remained unchanged following the administration of triiodothyronine.In contrast to normal liver, Hepatoma 5123 A has shown in all subcellular fractions the presence of polarographically active, non‐protein SH‐compounds. In normal rat liver these compounds appear only in the mitochondrial fraction and their level is much lower than in Hepatoma 5123 A.It is suggested that the Warburg type of metabolism in Hepatoma 5123 A may be a manifestation of structural and functional insufficiency of preformed cytoplasmic elements.