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KMID : 0382619810010010147
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Hanyang Journal of Medicine
1981 Volume.1 No. 1 p.147 ~ p.159
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Activities and Properties of Ribonucleases in Human Cervical Cancer Tissues
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朴連秀/Park, Youn Su
金斗相/高在炅/Kim, Doo Sang/Koh, Jai Kyung
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Abstract
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Extensive studies have been carried out for more than a decade to clarify the, causative agents of carcinoma of the uterine cervix. Although the exact cause of this disease has not been elucidated, it has been suspected that the generally transmitted carcinogen which may cause cervical cancer could be sperm or herpes simplex virus type f. (HSV- II ). It has been shown that a number of enzymes. involved in nucleic acid metabolism are increased in their activities after viral infection in animal model system for the study of carcinogenesis. A series of studies on acid deoxyribonuclease (DNase) in human cervical cancer cells indicated. that the enzyme in cervical cancer cells was greatly increased over that from normal cells of uterine cervix, might be specific for the cancer cell and cleaved double stranded DNA endonucleolytically, suggesting that the acid DNase may play a crucial role in transforming normal cells into cancer cells probably by integrating a fraction of sperm DNA or HSV- ff DNA into host chromosomal genome.
It has recently been shown that activities of ribonuclease (RNase) were changed in certain types of cancer cells and were significantly increased in serum from patients with pancreatic and ovarian cancer. These results suggest that, although. the exact mechanism by which RNase activities in cancer cells and serum were: changed has not been clarified, RNase may play an important role in carcinoge-, nesis and in -metabolic processes of cancer cells. In order to understand a possible: involvement of RNase in human cervical cancer cells, activities of RNase in the: cancer cells were determined and properties of the enzyme were studied in the: present study. Also determined were activities of RNases in serum from patients. with cervical cancer, investigating whether the enzyme activities were changed in cancer serum.
A pH-activity profile for RNases in cervical cancer cells showed that, while a - maximum activity was observed at pH 5.5, a small but definite peak for RNase activity appeared to be present at pH 9.2. These results indicate that cervical cancer cells contain at least two types of RNases, acid and alkaline RNases, and that acid RNase was found to be the major enzyme in the cancer cells. While activity of alkaline RNase in cervical cancer cells was unchanged, activity of acid RNase was greatly increased in cervical cancer cells as compared with that -of normal cells of uterine cervix. This probably suggests that the increased activity of acid RNase activity seen in cervical cancer cells could be responsible for an elevated degradation of RNA to ribonucleotides so as to raise the supply of the substrate for the synthesis of cancer specific RNA.
Observations that the activity of acid RNase in cervical cancer cells was inhibited by DNA and that the activity of acid DNase was suppressed by polyadenylate (poly A) indicate that activities of enzymes involved in degradation of nucleic acids are regulated not only by natural protein in hibitors but also by nucleic acids. It was found in cervical cancer cells that the activity of acid DNase was higher than that of acid RNase and that the magnitude of inhibition of acid RNase by DNA was greater than that of acid DNase by poly A. The results suggest that in cervical cancer cells the biochemical events catalyzed by acid DNase preferentially proceed as compared with those catalyzed by acid RNase.
The mean value of serum acid RNase activity in patients with cervical cancer appeared to be higher than that in normal persons, but exhibited no statistical significance.
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