氯乙基亚硝基脲导致DNA股间交联的荧光光谱法研究

Agarose Gel Electrophoresis and Fluorometric Study on DNA Interstrand Cross-links Induced by Chlorethylnitrosoureas

氯乙基亚硝基脲(CENUs)是重要的临床抗癌药物,其抗癌作用机制与导致DNA股间交联密切相关。使用荧光光谱法对其导致的DNA股间交联进行定量分析。结果表明,交联率随着反应时间的延长逐渐增加,司莫司汀(Me-CCNU)和卡莫司汀(BCNU)的交联率分别约在8 h和5 h达到最大值,且药物浓度越大,交联率增加越快。比较了Me-CCNU和BCNU对DNA交联作用的反应动力学,发现分解较慢的Me-CCNU与DNA的交联过程中存在一段明显的"诱导期";而分解较快的BCNU与DNA的交联反应则不存在"诱导期",且BCNU浓度过高或反应时间过长均会使交联率下降。该文为阐明CENUs导致DNA交联的反应动力学和反应机理提供了依据。

Chlorethylnitrosoureas （CENUs） are significant antieancer drugs in the clinical treatment of human malignancies. Several lines of evidences indicated that their antieaneer mechanism was related to the formation of DNA interstrand eross-links（ICLs）. Quantitative analyses were carried out to in- vestigate the DNA ICLs using spectrofluorometrie methods. The results showed that the cross-link fraction （CF%） increased progressively accompanied with reaction time. The CF% reached the maxi- mum value when DNA had been treated with Me-CCNU and BCNU for about 8 h and 5 h, respective- ly. The reaction kinetics of the formation of ICLs was compared between Me-CCNU and BCNU. An obvious ＂induction period＂ was observed in the formation of ICLs induced by Me-CCNU, but was not observed in that of BCNU for its faster decomposation. Moreover, high concentration and long reaction time of BCNU led to the decrease of the CF% values. This research provided evidences for the clarification of the reaction kinetics and mechanism of DNA ICLs induced by CENUs.