A TOXIC CANCER TISSUE CONSTITUENT AS EVIDENCED BY ITS EFFECT ON LIVER CATALASE ACTIVITY

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The production of some toxic substance by cancer tissue has long been suspected, but due to the lack of adequate criterion, upon which to base the assay of such a substance, previous reports along this line added little substantial knowledge on the subject. Our recent experiments to be briefly described in this paper may be of interest in this connection.
The starting point of our experiments was furnished by the observations of Greenstein and his associates, who found that the liver catalase activity of tumor bearing, rats and mice was markedly reduced, and that the extirpation of the tumor caused the liver catalase to rapidly return to normal, re-implantation with tumor causing liver catalase to drop again. By demonstrating that tumor tissue has no direct action in vitro on liver catalase, they concluded that the tow liver catalase activity of tumor bearing animals is ascribable to the reduction in amount of total catalase present in liver.
A natural inference from these observations may be that tumor tissue produces some toxic substance which, acting upon liver cells, serves to reduce their catalase content. In the hands of Greenstein, however, tumor extracts injected intraperitoneally into normal rats produced no change in the liver catalase activity of these animals. This apparently paradoxical result can be explained only on the assumption that the toxic substance in question occurs in tumor tissue in a low concentration and it requires a very large quantity of an ordinary tumor extract to deliver a sufficient amount of the substance to affect the liver catalase activity. This difficulty may be overcome by concentrating the hypothetical toxic substance.