Activities of ribonuclease(RNase) and RNase inhibitor reported to be involved in carcinogenesis process were determined in the renal cell carcinoma tissue. RNase and RNase inhibitor specific to the cancer were isolated from the renal cell carcinoma tissue. Substrate specificity and other properties of the enzyme and enzyme inhibitor were studied and their interaction was investigated.
RNase activity in the renal cell carcinoma tissue was significantly dicreased with the use of poly C for RNase activity was higher in the cancer tissue than the control tissue. Activity of RNase inhibitor was significantly increased and inhibitor/RNase ratio was markedly higher in the cancer tissue.
Proteins in the renal cell carcinoma tissue were separated by a DEAE-cellulose column chromatography into 6 peaks, of which five peak proteins exhibited RNase and RNase inhibitor activities. Activities of RNase and RNase inhibitor in four RNase isozyme fractions except for RNase isozyme I were lower in the cancer tissue than in the control tisseu, but RNA/poly C ratio for RNase activity and inhibitor/RNase ratio were higher in the cancer tissue than the control tisssue. The inhibitor activity of the RNase isozyme I fraction was higher in the cancer tissue than the control, and RNA/poly C ratio for the RNase activity and inhibitor/RNA ratio were markedly higher in the isozyme I fraction of the cancer tissue.
The RNase isozyme I isolated from the renal cell carcinoma tissue was highly active toward poly AC and AU, the activity being decreased toward poly C, AU, U, RNA, poly CIU, CU, CI in order. No activity was observed toward poly AGU, AG, GU, poly dA and dT. Substrate specificity of the RNase isozyme I from the cancer tissue was similar to that of the isozyme I from the control tissue in pattern but differ in that relative activity toward poly CU, AC, ACU, U and RNA was higher in the isozyme I from the cancer tissue than from the control tissue.
The present study were summerized that (1) RNase acitivity was significantly decreased and RNase inhibitor activity was increased in the renal cell carcinoma tissue, (2) ratio of RNA/poly C for RNase activity and inhibitor/RNase ratio were higher in the RNase isozyme I from the renal cell carcinoma tissue than that from the renal control tissue and (3) substrate specificity was different between the two tissues. These results indicated that the RNase isozyme I isolated from the renal cell carcinoma tissue is specific to the cancer and that the isozyme appears to be regulated strongly by the RNase inhibitor, suggesting an important role of the isozyme in carcinogenesis of the renal cell carcinoma.
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