Neutral ribonucleases (RNases) in the cystic fluid of ovary in patients with serous cyst, mucinous and serous cystadenocarcinoma were isolated and fractionated by a DEAE-cellulose column chromatography. The neutral RNases thus isolated were subject to determine the substrate specificity using homo-and hetero-polyribonucleotides to evaluate the nature and mechanism of action of the enzyme.
1. The activity of neutral RNase in the cystic fluid in mucinous and serous cystadenocarcinoma was significantly increased as compared with that in serous cyst as contraol. The positive rate of the neutral RNase activity as a marker for ovarian cancer appeared to be high in both serous and mucinous cystadenocarcinoma.
2. Neutral RNases in the cystic fluid in serous cyst, mucinous and serous cystadenocarcinoma were isolated by a DEAE-cellulose column chromatography into 4, 7 and 8 peaks, respectively.
3. Substrate specificity of the peak neutral RNases isolated from the cystic fluid of serous cystadenocarcinoma was observed to be highly active toward poly C and poly AC, the activity being decreased in the order of poly CI, poly CU, poly CIU and poly U.Little activity was observed toward poly A and poly G. Substrate specificity of the peak neutral RNases isolated from the cystic fluid of serous cyst and mucinous cystadenocarcinoma was generally similar to that of serous cystadenocarcinoma. The ratio of neutral RNase activity measured using poly C as substrate to the enzyme activity measured using polyribonucleotides other than poly C was different, in part, among three kinds of cystic fluid studied.
These results indicate that neutral RNases in the cystic fluid of ovarian cancer are present in the form of multiple isozymes, of which more than three neutral RNases are found to be specific for mucinous cystadenocarcinoma and more than four neutral RNases for serous cystadenocarcinoma.
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