Akbas S Halide, Timur Mujgan, Ozben Tomris
Department of Biochemistry, Akdeniz University, Faculty of Medicine, Antalya, Turkey.
J Surg Res. 2005 May 1;125(1):49-55. doi: 10.1016/j.jss.2004.11.011.
Topotecan, which is a Camptothecin derivative, shows a large spectrum in anti-tumor activity. Topotecan exerts its cytotoxic effect on tumor cells mainly by inhibition of topoisomerase I activity resulting in double-strand DNA breaks. In our study, we investigated the combined cytotoxic action of Topotecan and Quercetin in MCF-7 and MDA-MB 231 human breast cancer cells. To examine the possible relation between the cytotoxic activity of Topotecan and oxidative stress, we measured ROS and nitrite levels in both human breast cell lines.
MCF-7 and MDA-MB 231 cells were exposed to Topotecan, Quercetin, or a combination of both agents for 24 h at 37 degrees C. The viability of the cells was measured using the colorimetric MTT (3-(4,5)-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. We determined reactive oxygen species and nitrite levels as indicators of oxidative stress in both cell lines with and without Topotecan and/or Quercetin incubations using fluorometric dichlorofluorescin diacetate (DCFH-DA) and diaminonaphtalene (DAN) assay.
The IC(50) concentration of Topotecan was 100 ng/ml in MCF-7 cell line and 160 ng/ml in MDA-MB231 cell line. Treatment with Quercetin enhanced cytotoxicity of Topotecan as 1.4-fold in MCF-7 and 1.3-fold in MDA-MB-231 cell line. A significant increment on ROS and nitrite levels was found in MCF-7 and MDA-MB-231 cells following Topotecan incubation.
Our results suggest that Topotecan has cytotoxic activity against both of the breast cancer cell lines in vitro. A combination with Quercetin increases efficacy of Topotecan in the treatment of breast cancers. Our results indicate that increased oxidative stress plays a role in the cytotoxic action of Topotecan.
拓扑替康是一种喜树碱衍生物，具有广泛的抗肿瘤活性。拓扑替康主要通过抑制拓扑异构酶I的活性导致双链DNA断裂，从而对肿瘤细胞发挥细胞毒性作用。在我们的研究中，我们调查了拓扑替康和槲皮素对MCF-7和MDA-MB 231人乳腺癌细胞的联合细胞毒性作用。为了研究拓扑替康的细胞毒性活性与氧化应激之间的可能关系，我们测量了这两种人乳腺癌细胞系中的活性氧（ROS）和亚硝酸盐水平。
将MCF-7和MDA-MB 231细胞在37℃下分别暴露于拓扑替康、槲皮素或两种药物的组合中24小时。使用比色法MTT（3-(4,5)-二甲基噻唑-2-基)-2,5-二苯基四氮唑溴盐）测定法测量细胞活力。我们使用荧光二氯荧光素二乙酸酯（DCFH-DA）和二氨基萘（DAN）测定法，在有和没有拓扑替康和/或槲皮素孵育的情况下，测定这两种细胞系中作为氧化应激指标的活性氧和亚硝酸盐水平。
拓扑替康在MCF-7细胞系中的IC50浓度为100 ng/ml，在MDA-MB231细胞系中为160 ng/ml。槲皮素处理增强了拓扑替康的细胞毒性，在MCF-7细胞系中增强了1.4倍，在MDA-MB-231细胞系中增强了1.3倍。在拓扑替康孵育后，MCF-7和MDA-MB-231细胞中的ROS和亚硝酸盐水平显著增加。
我们的结果表明，拓扑替康在体外对两种乳腺癌细胞系均具有细胞毒性活性。与槲皮素联合使用可提高拓扑替康治疗乳腺癌的疗效。我们的结果表明，氧化应激增加在拓扑替康的细胞毒性作用中起作用。
