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目的通过顺铂(CDDP)与替尼泊甙(VM-26)联合作用,探讨顺铂增强替尼泊甙对小细胞肺癌细胞株杀伤作用的机制。方法用MTT法,测定H446小细胞肺癌细胞24 h抑制率;AO/EB双荧光染色观察细胞活率;琼脂糖凝胶电泳检测DNA断裂条带;半定量RT-PCR及蛋白印迹检测DNA拓扑异构酶Ⅱ(TopoⅡ)及特化蛋白1(SP1)的表达。结果CDDP与VM-26联合应用有明显的协同效应;二药合用与单独用药相比,细胞活率明显降低,DNA损伤程度增加。H446细胞经CDDP单独作用可以促进SP1、TopoⅡα和TopoⅡβmRNA及蛋白的表达;经VM-26单独作用后,TopoⅡα和TopoⅡβmRNA及蛋白表达降低,而SP1表达无明显改变;二药合用后可见TopoⅡαmRNA及蛋白的表达比单独应用CDDP下调,SP1 mRNA及蛋白的表达比单用VM-26升高,但与单用CDDP相比没有明显变化。结论CDDP通过上调SP1促进H446细胞中TopoⅡ表达,为TopoⅡ抑制剂类药物VM-26提供更多的作用靶点,能够明显提高对小细胞肺癌的抑制作用。
OBJECTIVE: To investigate the mechanism of cisplatin in enhancing the killing effect of teniposide on small cell lung cancer cell lines by the combined action of cisplatin (CDDP) and teniposide (VM-26). Methods MTT assay was used to determine the inhibitory rate of H446 cells for 24 h. AO / EB double staining was used to observe the cell viability. DNA fragmentation was detected by agarose gel electrophoresis. Semiquantitative RT-PCR and Western blotting were used to detect the DNA topoisomerase Topo II and SP1 (SP1). Results The combination of CDDP and VM-26 had obvious synergistic effect. The combination of two drugs significantly reduced the cell viability and the DNA damage compared with the single drug. The expression of SP1, TopoⅡα and TopoⅡβmRNA and protein in H446 cells were promoted by CDDP alone. The expression of TopoⅡα and TopoⅡβmRNA and protein was decreased and the expression of SP1 was not changed by VM-26 alone. The combination of TopoⅡαmRNA and protein Compared with CDDP alone, the expression of SP1 mRNA and protein was higher than that of VM-26 alone, but no significant difference compared with CDDP alone. Conclusions CDDP can promote TopoⅡexpression in H446 cells by up-regulating SP1 and provide more targets for TopoⅡinhibitor VM-26, which can significantly improve the inhibitory effect on small cell lung cancer.