CREATINE-KINASE ACTIVITY AND ISOENZYMES IN LUNG, COLON AND LIVER CARCINOMAS

We have compared the levels of creatine kinase (CK) activity and the d istribution of CK isoenzymes determined by agarose gel electrophoresis in normal colon, liver and lung tissues, and in colon, liver and lung adenocarcinomas, lung squamous cell carcinomas and lung carcinoids. C olon and lung adenocarcinomas, and squamous cell carcinomas presented lower CK activity than the normal tissues and no differences were foun d between hepatocarcinoma and normal liver tissue. In contrast, lung c arcinoids had higher CK activity than normal lung tissue. Type BB-CK w as the predominant isoenzyme in normal lung, colon and liver tissues. Type MM isoenzyme was detected in normal lung and type MB-CK was found in normal colon. In most lung tumours the CK isoenzyme electrophoreti c pattern did not change. However, no type BB-CK was detected in some hepatocarcinomas, type MM-CK decreased in lung carcinoids and type MB isoenzyme was not observed in colon adenocarcinomas. It is concluded t hat in most tumours there is a decrease in the expression of type B-an d type M-CK subunits, whereas in lung carcinoid the expression of type B-CK activity increases. Thus, the increase in type BB-CK observed in the serum of patients with lung and colon adenocarcinomas is probably due mainly to enhanced enzyme release as a result of tumour cell necr osis.