Abstract

Thymidine kinase(TK) and proliferating cell nuclear antigen(PCNA) are similar in the aspect that both are a part of protein complex group of cellular DNA synthesis and expression period during cell cycle is Gl-S phase. From 30 surgically resected cancers of digestive organs(20 gastric adenocarcinomas and 10 hepatocellular carcinomas), we evaluated TK activity and PCNA labeling index in normal and tumor tissues in order to know the correlation between them and the value as an independent prognostic factor. TK activity of tumor tissue(5.14 nmol/hr/mg) was higher than that of normal tissue(2. 95 nmol/hr/mg). PCNA labeling index of tumor tissue(54.3%) was higher than that of normal tissue(21.4%). According to the originated organ, both gastric and hepatic malignancies revealed higher TK activity and PCNA labeling index than normal tissues. There was a significant correlation between TK activity and PCNA labeling index. In gastric adenocarcinoma, ratio of TK activity between normal and tumor tissue was higher in poorly differentiated group than well or moderately differentiated group. In hepatocellular carcinoma, ratio of TK activity between normal and tumor tissue was higher in the positive capsular invasion group than the nagative. As a conclusion, the TK activity and PCNA labeling index represented the biologic activity of tumor cells and could be used as independent prognostic factors.

• Keywords: Thymidine kinase, Proliferating cell nuclear antigen (PCNA), Gastric cancer hepatocellular carcinoma