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A Comparison of Activators of Proteolytic Enzymes and Peptidases in Normal Rat Livers and Hepatomas^*

(From the Medical Laboratories of the Collis P. Huntington Memorial Hospital, of Harvard University, Located at the Massachusetts General Hospital, Boston 14, Massachusetts)

The cathepsin-activating ability of ultrafiltrates prepared from hepatomas has been found to be considerably less than that of various types of control livers. Since sulfhydryl groups are the most common cathepsin activators found in tissues, we have looked for a possible correlation of the above finding with the glutathione concentrations of the hepatomas. The hepatoma ultrafiltrates had both the lowest glutathione concentrations and the least cathepsin-activating power. The fetal livers, however, had a low glutathione concentration but the greatest cathepsin-activating ability. It is evident, therefore, that the cathepsin may be activated by more than one tissue component.

Glutathione appears (in the normal liver, in the regenerating liver, and in the hepatoma) to be a major cathepsin-activating agent and to be particularly low in the hepatoma. It is thus possible that the increased growth rate of this type of hepatoma may be related to a decrease in the concentration of the glutathione component of one of its protein-degrading mechanisms.

^* Supported by the Godfrey M. Hyams Fund and by a grant-in-aid from the American Cancer Society (recommended by the Committee on Growth of the National Research Council).

This is Publication No. 662 of the Cancer Commission of Harvard University.

Presented at the Fourth International Cancer Research Congress, St. Louis, Missouri, September 5, 1947.