Differences in thermostability of thymidine kinase isoenzymes in normal ovary and ovarian carcinoma

A. Demeter, M. Abonyi, K. Y. Look, G. Keszler, M. Staub, G. Weber

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5 Citations (Scopus)


Thymidine kinase I (TK 1 EC. the most specific and cell-cycle regulated salvage enzyme for pyrimidine nucleoside supply of DNA synthesis is a promising target to rationally designed chemo- and other therapies. The present study was undertaken to compare the heat stability of TK isoenzymes of both normal ovarian and epithelial ovarian cancer cells. Tissue extracts of epithelial ovarian carcinomas (N = 7) and normal ovaries (N=9) were analyzed for thymidine kinase activity using the polyethyleneimine-cellulose disc radioassay. The TK activity in extracts of ovarian carcinomas was 12-fold higher than in extracts of normal ovaries. The TK activity of ovarian carcinomas decreased significantly even after 30 minutes incubation at 37°C while, the enzyme activity of normal ovarian extracts was more stable and decreased to the same extent after 120 minutes. The half-life time of the enzyme activy was 82 min in the normal but only 36 minutes in the cancer tissue extract at 37°C. Conclusion: The TK activity of malignant ovarian cells was much higher but more unstable (t1/2=36 minutes) than the enzyme isolated firm healthy ovaries (t1/2=82 minutes). This profound difference in thermostability might provide the molecular background for hyperthermia combined with chemotherapy as a promising treatment for ovarian malignancies.

Original languageEnglish
Pages (from-to)353-358
Number of pages6
JournalAnticancer research
Issue number1 A
Publication statusPublished - Apr 17 2001



  • Heat-sensitivity
  • Hyperthermy
  • Ovarian cancer
  • Thymidine kinase

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

Cite this

Demeter, A., Abonyi, M., Look, K. Y., Keszler, G., Staub, M., & Weber, G. (2001). Differences in thermostability of thymidine kinase isoenzymes in normal ovary and ovarian carcinoma. Anticancer research, 21(1 A), 353-358.