Endocrine Abstracts

Thymidine kinase 1 (TK1), deoxycytidine kinase (dCK), and thymidine phosphorylase (dThdPase) are the enzymes involved in pyrimidine and purine metabolism; TK1 activity is correlated with growth processes, and dThdPase is involved in the mechanisms of angiogenesis. The increased activities of TK1, dCK and dThdPase or the increased expression of genes for theses enzymes have been found in different tumors. The aim of the study was to estimate the expression of mRNA, specific for the enzymes in question, in the tissue of human papillary thyroid carcinoma (PTC) and of human medullary thyroid carcinoma (MTC), obtained from postoperative material after total surgery. An approval of the Ethical Committee of the Medical University of Lodz has been obtained. The expression of TK1 and of dThdPase was estimated in the tissue of PTC only, and the expression of dCK was measured both in the tissue of PTC and MTC; the expression of RNA for all the enzymes was also measured in macroscopically unchanged thyroid tissue, collected from the same patients. Reverse transcriptase-polymerase chain reaction (RT-PCR) and densitometry were employed for mRNA expression evaluation, and beta-actin gene served as the supervisory gene. The expression of mRNA for TK1, dCK and dThdPase in the tissue of PTC, as well as the expression of mRNA for dCK in MTC, were significantly higher than those in macroscopically unchanged thyroid tissue. The results suggest that the increased expression of RNA, specific for TK1, dCK and dThdPase, plays a role in neoplastic processes in the human thyroid, i.e., in the pathogenesis of papillary and/or medullary carcinoma.