COMPARISON OF ANTITUMOR ACTIVITIES OF PANCREATIC RIBONUCLEASE AND ITS CROSS-LINKED DIMER

  • 1 January 1976
    • journal article
    • research article
    • Vol. 36  (11) , 4074-4078
Abstract
The cross linked dimer of bovine pancreatic RNase (M W 28,000) is significantly more effective than the monomer in inhibiting tumor development in mice when administered i.p. 1 day after inoculation with sarcoma 180J ascites cells. Animals bearing solid tumors were not affected. In AKR/J mice with advanced leukemia, a single i.p. injection of 100 .mu.g of the dimer led to about 50% reduction in the enlarged lymph nodes and spleen at 24 h. The half-life of the dimer in the bloodstream was determined to be 10 min in rats and 6 min in mice, compared to values of 5 and 3.5 min, respectively, for the monomer. Analyses of the tissues of untreated leukemic mice for RNAase and RNase inhibitors showed that the tumor tissues are not deficient in RNase activity. Considerations of possible mechanisms of action of the dimer indicate that other basic proteins in this size range may merit examination of cytostatic agents toward transformed cells.

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