Activity of ribonuclease(RNase) was determined with polycytidylate(poly C) and RNA as substrate in the cerebrospinal fluid(CSF) of patients with hepatocellular carcinoma with coma. RNases and proteins in the CSF of patients with hepatocellular carcinoma were isolated and purified by a DEAE-cellulose column chromatography and high performance liquid chromatography (HPLC). Substrate specificity for the purified RNase activated in the CSF of the cancer patient was detemined to evaluate the possible role of the RNase in carcinogenesis.
Activity of RNA measured with poly C and RNA as substrate and ratio of RNA/poly C for the RNase activity in the CSF were increased significantly in the hepatocellular carcinoma, but were unchanged in the liver cirrhosis. The positive rate of the RNase activity in the CSF as a marker for hepatocellular carcinoma was high, suggesting the use of the RNase activity in the CSF as a marker for hepatocellular carcinoma.
Proteins and RNases in the CSF of the patient with hepatocellular carcinoma were separated into 7 protein peaks and 5 RNase isozymes(isozyme I, Ⅳ-Ⅶ), of which two peak proteins and one RNase isozyme(isozyme I) were specific to the hepatocellular carcinoma.
The RNase isozyme I purified from the CSF of the cancer patient was a major isozyme of the RNase isozymes isolated, was activated and was higher in ratio of RNA/poly C for the RNase activity, exhibiting more of nonsecretory RNase nature than that from the CSF of the control.
The RNase isozyme I fraction in the CSF of the patient with hepatocellular carcinoma was separated by a HPLC into four subpeaks, of which subpeak I-3 exhibited RNase activity. The RNase isozyme I (I-3) purified from the CSF of the patient with hepatocellular carcinoma showed the highest activity toward poly AC as substrate, the degree of activity being decreased toward poly ACU and C, AU, CI, CIU, CU, RNA, poly U in order. No was observed with poly A, G, AG and GU.
The substrate specificity toward the RNase isozyme I from the CSF of the cancer patient appeared to be different from that of the control in that relative activity toward RNA, poly U, CI, AC, AU, CIU and ACU over poly C was higher in the isozyme from the CSF of the cancer patient than in the isozyme from the CSF of the control. The result indicated that the RNase isozyme I from the CSF of the cancer patient was different in nature from the isozyme from the CSF of the control.
Observations that in the CSF of the patient with hepatocellular carcinoma with hepatic coma, (1) five RNase isozymes were isolated, (2) of which one isozyme(isozyme Ⅳ) was specific to hepatocellular carcinoma, (3) the RNase isoyzme I isolated as a major enzyme was activated and (4) the substrate specficity of the isozyme in the CSF of the cancer patient was different from that in the CSF of the control, suggested that the RNase isozyme I in the CSF of the cancer patient might be involved in carcinogenesis processes of hepatocellular carcinoma.
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