Several rat and mouse hepatomas and the liver and kidneys of the host animals were assayed for catalase activity. Little or no activity could be demonstrated in the subcutaneously transplanted Novikoff hepatoma, Hepatoma LC18, and Hepatoma 3683 of rats, and in a number of transplanted hepatomas of mice and hamsters. A relatively high activity was found, however, in the transplanted Hepatoma 5123 and the ethionine-induced hepatomas of rats, and in the spontaneous hepatomas of C3H mice, even though a definite depression was observed in the catalase activity of the liver and kidneys of these tumor-bearing animals. In animals bearing transplanted Hepatoma HC the catalase activity of the tumor was exceedingly high, often exceeding the levels observed in the liver and kidneys.

The catalase level of Hepatoma 5123 was not altered under the stress of a protein-free diet which produced a characteristic lowering in the liver catalase of both normal and tumor-bearing animals. Similarly, both sex and age significantly altered the level of the tissue catalase activity of the host but had no apparent effect on the level of the hepatoma catalase. The site of the tumor implantation also did not change the levels of catalase activity of the tumor tissue.

The significance of these data is discussed with reference to the concept of “toxohormone” being released by tumors to produce a lowering of the catalase activity in the host tissues.


Presented in part at the 52nd Annual Meeting of the American Association for Cancer Research, Atlantic City, N.J., April, 1961 (48).

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