叶酸修饰稀土改性载氧碳纳米管增加乳腺癌细胞株放疗敏感性的体外实验初步研究

目的:研究叶酸修饰稀土改性载氧碳纳米管在低氧环境下对乳腺癌细胞株放疗敏感性的影响。方法:使用水溶性四唑盐法(WST-1)方法研究叶酸修饰稀土改性载氧碳纳米管对MDA-MB-231细胞与ZR-75-1细胞生长的作用,使用细胞集落形成实验研究其在低氧环境下对无叶酸培养基中MDA-MB-231细胞、有叶酸培养基中MDA-MB-231细胞及ZR-75-1细胞放疗敏感性的影响。利用流式细胞术研究叶酸修饰稀土改性载氧碳纳米管联合放疗干预MDA-MB-231乳腺癌细胞株的凋亡率的改变。利用Western Blot实验观察Bcl-2、survivin、Hif-1α、Rad51及Ku80表达水平的改变。结果:在常氧及低氧环境下,叶酸修饰稀土改性载氧碳纳米管在低于100μg/ml的浓度时对乳腺癌细胞株生长无明显影响。在低氧环境下,放疗联合叶酸修饰稀土改性载氧碳纳米管组相比于单纯放疗组细胞克隆形成率有不同程度的降低,以无叶酸培养基中MDA-MB-231细胞组降低最为明显,照射剂量在2、4、6、8Gy时其细胞克隆形成率均显著降低(P0.05)。流式细胞术显示叶酸修饰稀土改性载氧碳纳米管联合放疗后可使MDA-MB-231乳腺癌细胞株的凋亡率增加。Western Blot实验显示Bcl-2、Survivin、Hif-1α、Rad51及Ku80表达水平均降低。结论:叶酸修饰稀土改性载氧碳纳米管可在体外低氧环境下增强乳腺癌细胞株对放疗的敏感性。

Preliminary Study of Oxygen Carried Rare Earth Modified Folate-decorated Chitosan-SWCNTs Increase the Radiosensitivity of Human Breast Cancer Cell Lines In Vitro

Objective:To determine whether oxygen carried rare earth modified folate-decorated chitosan-SWCNTs (R-O2-FACHI- SWCNTs) could increase the radiosensitivity of human breast cancer cell lines.Methods:WST-1 assay was used to determine the cytotoxicity of the new synthesized R-O2-FA-CHI-SWCNTs on MDA-MB-231 and ZR-75-1 cells. MDA-MB-231 cells in folic acid free medium, MDA-MB-231 cells in medium containing folic acid, and ZR-75-1 cells were treated with different doses of radiotherapy with or without R-O2-FA-CHI-SWCNTs under hypoxic condition. Colony forming assay was used to determine the cell surviving fractions. Cell apoptosis induction was monitored by flow cytometry. Expression of Bcl-2, Survivin, Hif-1alpha, Rad51 and Ku80 was monitored by Western blotting.Results:The WST-1 assay revealed that R-O2-FA-CHI-SWCNTs had no significant cytotoxicity on breast cancer cells when the concentration of R-O2-FA-CHI-SWCNTs was below 100 ug/ml under normoxic or hypoxic condition. Under hypoxic condition, the administration of R-O2-FA-CHI-SWCNTs plus radiotherapy yielded lower colony forming efficiency compared to radiotherapy alone, especially in MDA-MB-231 cells in folic acid free medium. The colony forming efficiency was reduced significantly when the radiation dose was 2,4,6 and 8Gy. Flow cytometric analysis revealed that the R-O2-FA-CHI-SWCNTs plus radiotherapy could increase the cell apoptosis rate of MDA-MB-231 cells. Furthermore, western blot demonstrated that the material exhibited its expected function by downregulating Bcl-2, Survivin, Hif-1alpha, Rad-51 and ku80.Conclusion:The new synthesized R-O2-FA-CHI-SWCNTs could significantly increase the radiosensitivity of human breast cancer cell lines in vitro.