The present study was to investigate changes in concentration of protein and nucleic acids and activities of nucleases- in the lung cancer tissues and to find out whether proteins and nucleases specific to the lung cancer were present in the lung cancer tissues. For this purpose, protein, DNA and RNA contents and activities of deoxy-ribonuclease (DNase) and ribonuclease (RNase) were determined in the epidermoid carcinoma, adenocarcinoma, oat cell carcinoma and large cell carcinoma tissues of the lung. Also isolated and fractionated were proteins, DNase and RNase in lung cancer tissues.
(1) While protein and DNA contents were unchanged, the concentration of RNA was significantly increased in the lung cancer tissues. The positive rate of RNA con-tent as a marker for lung cancer appeared to be high (55%) in epidermoid car-cinoma.
(2) Activity of acid DNase was significantly increased by 2.3 fold and the positive rate of the enzyme activity as a marker for lung cancer was hight (50%) in epid-ermoid carcinoma tissue.
(3) The activity of. neutral RNase was unchanged, but acid RNase activity was significantly increased. And the positive rate of the acid RNase activity as a marker for the lung cancer was also high (35%) in epidermoid carcinoma tissue.
(4) DEAE-cellulose column chromatographical analyses revealed that no acid DNase peak unique to the lung cancer was observed, but a single RNase peak specific to the lung cancer was present and a single protein peak found in control tissue disappeared in epidermoid carcinoma tissue.
These results indicated that measurements of acid DNase and RNase activities could be used as biochemical markers for lung cancer especially for epidermoid carcinoma, and that alterations of protein and nucleic acid metabolism occured in multiple in the lung cancer tissue.
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