Plasma oncomodulin is proportional to tumour burden in rats bearing Morris hepatomas 5123D, 5123tc, 7288 and 7777

The small acidic calcium-binding protein, oncomodulin, was detected by radioimmunoassay in the plasma of rats bearing Morris hepatomas 5123D, 5123tc, 7288ctc, and 7777. The concentration of plasma oncomodulin was proportional to the tumour burden. When the tumour was surgically removed, the plasma oncomodulin level dropped to undetectable levels. No oncomodulin was detected in the circulation of normal rats.     

Glycosphingolipids of subcellular fractions from normal rat liver and Morris hepatoma 5123TC.

Neutral glycosphingolipids and gangliosides were quantified in lipid extracts from plasma membranes, mitochondria, microsomes, and nuclei isolated from normal rat liver and Morris hepatoma 5123TC. Results showed a higher content of glycosphingolipids, especially gangliosides, in hepatomas and differences in the distribution of glycosphingolipids among subcellular fractions. Differences in the glycosphingolipid composition of the hepatoma, namely, the absence of trisialogangliosides and an increase in the lower molecular weight gangliosides, reflected an altered metabolism of glycosphingolipids in this tumor. The results indicated that changes in membrane glycosphingolipids were not restricted to the cell surfaces of malignant cells, inasmuch as intracellular membrane fractions also exhibited altered glycosphingolipid profiles.     

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

Evidence 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.     

Temperature effects on the modulation of adenylate cyclases from rat liver and Morris hepatomas.

When adenylate cyclase activities in purified membranes from normal rat liver and from a series of rapid growing transplantable Morris hepatomas were examined at various temperatures, several unique features were observed. Two of the hepatomas yielded patterns similar to that of normal liver, even though glucagon did not activate either tumor adenylate cyclase but did activate the normal liver enzyme. The patterns of the third tumor line were completely different from normal. This clearly shows the heterogeneity in cancers of similar origin.