Increased thymidine kinase and thymidylate synthase activities in human epithelial ovarian carcinoma.
Increased thymidine kinase and thymidylate synthase activities in human epithelial ovarian carcinoma.
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发表时间：
1997-07
影响因子：
2
通讯作者：
K. Look;David H. Moore;Gregory P. Sutton;N. Prajda;M. Abonyi;George Weber
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作者：
K. Look;David H. Moore;Gregory P. Sutton;N. Prajda;M. Abonyi;George Weber
研究背景胸腺嘧啶酸合成酶(DTMP Synthase，EC 2.1.1.45)负责胸苷(DTMP)的从头合成，而胸苷激酶(TdR Kinase，EC 2.7.1.21)是在d-TMP合成酶抑制的情况下导致DTMP产生的抢救酶。本研究比较了人上皮性卵巢癌和正常卵巢提取液中d-TMP合成酶和TDR激酶的稳态活性。材料与方法测定卵巢上皮性癌和正常卵巢组织提取液中d-TMP合成酶活性(用3H2O释放法)和TDR激酶活性(用聚乙烯亚胺浸渍(PEI)纤维素板放射分析法)。结果DTMP合酶活性(平均值+/-S.E.)卵巢癌组织(n=11)和正常卵巢组织(n=12)提取液中蛋白质含量分别为0.198+/-0.069和0.025+/-0.0004 nmol/小时/mg蛋白。而卵巢癌组织(N=13)和正常卵巢组织(N=15)的TDR激酶活性分别为27.7+/-8.5和1.0+/-0.3nmol/小时/mg蛋白。结论在目前的5-氟尿嘧啶(5-FU)和亚叶酸钙方案下，即使DTMP合成酶被抑制，DNA合成仍可继续进行。联合5-FU和亚叶酸钙治疗难治性卵巢癌可能是一种合理的生化策略。
BACKGROUND Thymidylate synthase (dTMP synthase, EC 2.1.1.45) is responsible for the de novo biosynthesis of thymidylate (dTMP) whereas thymidine kinase (TdR kinase, EC 2.7.1.21) is the salvage enzyme which leads to the production of dTMP even in presence of d TMP synthase inhibition. The current study was undertaken to compare the steady-state activities of d TMP synthase and TdR kinase in extracts of human epithelial ovarian carcinoma and normal ovaries. MATERIAL AND METHODS Tissue extracts of epithelial ovarian carcinomas and normal ovaries were analyzed for activities of d TMP synthase (by a method that measures released 3H2O) and TdR kinase (by polyethyleneimine impregnated (PEI) cellulose plate radioassay), methods established in this laboratory. RESULTS The dTMP synthase activity (mean +/- S.E.) in extracts of ovarian carcinomas (N = 11) was 0.198 +/- 0.069 and in extracts of normal ovaries (N = 12) it was 0.025 +/- 0.0004 nmol/hr/mg protein. By contrast, TdR kinase activity in extracts of ovarian carcinoma (N = 13) was 27.7 +/- 8.5 compared to 1.0 +/- 0.3 nmol/hr/mg protein in extracts of normal ovaries (N = 15). CONCLUSION The observed 140-fold higher TdR kinase activity suggests that DNA synthesis may continue despite inhibition of dTMP synthase with current schedules of 5-fluorouracil (5-FU) and leucovorin. The addition of azidothymidine, a competitive inhibitor of TdR kinase, to 5-FU and leucovorin might be a rational biochemical strategy to employ in patients with refractory ovarian carcinoma.