Dardalhon M, Guillo L A, Moysan A, Vigny P, Averbeck D
Institut Curie-Biologie, URA 1292 du CNRS, Paris, France.
Photochem Photobiol. 1994 Apr;59(4):423-9. doi: 10.1111/j.1751-1097.1994.tb05059.x.
The photochemotherapeutically active psoralen derivative 7-methylpyrido(3,4-c) psoralen (MePyPs) has been recently shown to be able to photoinduce monoadducts of the C4-cycloaddition type as well as pyrimidine dimers in DNA in vitro. In the present study, we report on the induction of these two types of photolesions in mammalian cells in culture. The MePyPs photocycloadducts were quantified in V79 Chinese hamster cells after treatment with MePyPs plus UVA following enzymatic hydrolysis of the DNA by DNase I, S1 nuclease and acidic phosphatase treatments. Concomitantly induced pyrimidine dimers were determined by two methods, high-pressure liquid chromatography and alkaline gel electrophoresis after dimer-specific endonucleolytic cleavage. The results show that, in Chinese hamster cells treated with MePyPs plus UVA, the yield of pyrimidine dimers is approximately 5-10% that of MePyPs-DNA photocycloadducts. Because psoralen monoadditions to DNA alone are generally not considered as being very phototoxic, a synergistic interaction of monoadditions with pyrimidine dimers may be expected to occur in order to explain the high photobiological effectiveness of this psoralen derivative.
光化学治疗活性补骨脂素衍生物7-甲基吡啶并(3,4-c)补骨脂素（MePyPs）最近已被证明在体外能够光诱导DNA形成C4-环加成类型的单加合物以及嘧啶二聚体。在本研究中，我们报道了在培养的哺乳动物细胞中诱导这两种类型的光损伤。在用MePyPs加UVA处理V79中国仓鼠细胞后，通过DNase I、S1核酸酶和酸性磷酸酶处理对DNA进行酶解，然后对MePyPs光环加合物进行定量。通过两种方法测定同时诱导产生的嘧啶二聚体，即二聚体特异性内切核酸酶切割后的高压液相色谱法和碱性凝胶电泳法。结果表明，在用MePyPs加UVA处理的中国仓鼠细胞中，嘧啶二聚体的产量约为MePyPs-DNA光环加合物产量的5-10%。由于单独的补骨脂素对DNA的单加成通常不被认为具有很强的光毒性，因此可以预期单加成与嘧啶二聚体之间会发生协同相互作用，以解释这种补骨脂素衍生物的高光生物学有效性。
