Ribonuclease and deoxyribonuclease activites in experimental and human tumors by the histochemical substrate film method.

Summary The ribonuclease and deoxyribonuclease activities of 65 experimental and human tumors (32 different types) have been examined by histochemical substrate film methods. A same general pattern was obtained for the distribution of both nucleases in the various types of experimental and human tumors. The connective tissue stroma and the necrotic regions of the tumor masses showed various levels of nuclease activity, whereas the neoplastic cells showed no demonstrable activity. It appears that deficiencies in ribonuclease and deoxyribonuclease activities represent general properties of cancer cells. The possible significance of the losses of nuclease activities in carcinogenesis is discussed.