DNase, RNase, & RNase Inhibitors as Markers for Hepatocellular Carcinoma

Kae, Sea Hyub; Chung, Yoo Sun; Jang, Heon Ju; Jung, Sun Wha; Kim, Yong Tae; Kang, Seung Sik; Lee, Jin; Kwak, Sang Taek; Joo, Sang Aun; Yoo, Jae Young

Abstract

OBJECTIVE
Activities of nucleases (acid DNase and neutral RNase) and RNase inhibitor known to be involved in carcinogenesis and suppression of cancer were determined in cancer tissue, serum and ascitic fluid of patients with hepatocellular carcinoma and were compared with those of the controls. Also studied were nucleases and RNase inhibitor isolated from hepatocellular carcinoma tissue and ascitic fluid of the cancer patients to evaluate the properties and interactions between them. METHOD: Activities of nucleases and RNase inhibitor were measured in cancer tissue, serum and ascitic fluid of patients with hepatocellular carcinoma by ultraviolet spectrophotometry. Nucleases and RNase inhibitor were isolated from hepatocellular carcinoma tissue and ascitic fluid of the cancer patients by DEAE-cellulose column chromatography. As controls, normal tissue of the cancer patients, serum of healthy persons and ascitic fluid of cirrhotic patients were used. RESULT: Activities of DNase, RNase and RNase inhibitor were significantly increased in hepatocellular carcinoma tissue. DNase activity was not detected, RNase activity was increased and RNase inhibitor activity was unchanged in both serum and ascitic fluid of the hepatocellular carcinoma patients. DNase was isolated as a single enzyme and RNase as seven isozymes from the hepatocellular carcinoma tissue. The DNase isolated preferentially cleaved ds DNA over ss DNA and was endonuclease in nature (majority of hydrolytic products of DNA by the DNase were oligodeoxyribonucleotides). Of seven RNase isozymes isolated from the hepatocellular carcinoma tissue, isozyme I exhibited nonsecretory nature of RNase and other six isozymes secretory nature of the enzyme. Activity of RNase isozyme V was greatly increased and the activity of inhibitor complexed with the isozyme V was also increased. RNase in ascitic fluid of the cancer patient was separated into four isozymes, of which isozyme I exhibited mixed form of secretory and nonseretory nature and greatly increased in its activity. RNase isozyme V isolated in the hepatocellular carcinoma tissue was not detected in the ascitic fluid.
CONCLUSION
The use of the nucleases and the inhibitor in the cancer tissue as biochemical markers for the hepatocellular carcinoma was suggested. RNase was released into the body fluid from the cancer tissue and could be used as a diagnostic marker for the hepatocellular carcinoma. An important role of the DNase in carcinogenesis of the liver was suggested. RNase isozyme V was limited in the cancer tissue and RNase isozyme I and V and inhibitors associated with these isozymes might be involved in carcinogenesis processes, suppression of cancer and maintenance of hepatocellular carcinoma through their interactions.