Ribonucleases(RNases) are known to be involved not only in the metabolism of nucleic acid, but also in carcinogenesis and suppression of cancer. The presence of RNase inhibitor in the mammalian tissues and its role on the RNases have been
suggested.
In order to investigate the interaction between RNase and RNase inhibitor in the cancer state, RNase the interaction between RNase and RNase inhibitor in the cancer state, RNase their inhibitors in ascitic fluid of patients with hepatocellular
carcinoma
were measured in their activity an isolated by a DEAE-cellulose column chromatography.
The RNase activity in ascitic fluid was increased in hepatocellular carcinoma by 525 over that of liver cirrhosis, and the positive rate of the enzyme as a maker for hepatocellular carcinoma was 56%, suggesting the use of the ascitic fluid RNase
as
a
biochemical marker for liver cancer. RNase activity in ascitic fluid of hepatocellular carcinoma and liver cirrhosis was activated by para-hydroxymercuribenzoate(PHMB), indicating the presence of Rnase indicating the presence of RNase inhibitor
in
the
ascitic fluid. Inhibitory activity to the RNase in the ascitic fluid was higher in hepatocellular carcinoma that liver cirhosis.
Proteins in ascitic fluid of hepatocellular carcinoma was isolated by a DEAE cellulose column chromatography into 7 peaks, of which 5 protein peaks exhibited RNase activity.
All RNase isozymes except for peak I Nrase isozyme isolated from ascitic fluid of hepatocellular carcinoma was activiated by PHMB indicating that RNase inhibitor was present in the from of RNase-inhibitor complex.
The peak VII protein uniequ to hepatocellular carcinoma showed no RNase activity, but exhibited RNase inhibitor activity toward both pancreatic RNase and RNase isozymes isolated from the ascitic fluid. The highest inhibitory activity of the peak
VII
protein was observed in peak V RNase isozyme and the lowest in peak I RNase isozyme, suggesting that interaction between RNase and RNase inhibitory appeared to be different from one RNase to another.
Observations that RNase inhibitor in the ascitic fluid of hepatocellular carcinoma is protein in nature, presents in the from of both free and bound RNase inhibitors and interacts differently with one RNase to another may indicated that the RNase
inhibitor regulates carcinogenic action and cancer suppressine action of RNase.
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