Subcellular Particles in Tumors-IV Lysosomes in Hepatoma HC and Morris Hepatomas 7794A, 7794B, 5123A, 7316A and 16

Document Type

Article

Publication Date

1-1-1970

Description

1. 1. The activities of seven acid hydrolases were measured in HC hepatoma and in Morris hepatomas 7794A, 7794B, 5123A and 16. In general the enzymes in the tumors exhibit a specific activity ranging between 50 and 150% of that found in rat liver tissue; however, the specific activities of acid phosphatase, N-acetylglucosaminidase and ß-galactosidase in hepatoma 5123A are far greater than those found in liver homogenates. 2. 2. The intracellular distribution of these enzymes was established after differential centrifugation in 0·25 M sucrose. The distribution pattern resembles that of the same enzymes in rat-liver homogenates. The enzymes are found mainly in the mitochondrial fractions and exhibit a peak of specific activity in the light mitochondrial fraction. 3. 3. Total mitochondrial fractions of hepatomas were analyzed by isopycnic centrifugation in a sucrose gradient and in gradients composed of glycogen dissolved in aqueous sucrose of different molalities. A number of physical properties of lysosomes were deduced from the behaviour of acid hydrolases in these experiments. The hepatoma lysosomes seem to have a larger sucrose space than the liver organelles. Injection of Triton WR1339, a non-ionic detergent, causes a distinct decrease in the equilibrium density of hepatoma lysosomes in a sucrose gradient similar to that observed for rat-liver lysosomes. 4. 4. Free activity of acid phosphatase, a reference enzyme for lysosomes, is increased by lowering the tonicity of the medium in which the granules are suspended and also by incubating the particles at pH 5 and 37°C in isotonic sucrose. HC hepatoma lysosomes appear to be significantly more resistant to this latter treatment than the granules of the other hepatomas.

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