中文摘要：

为了研究具有耐药性的卵巢癌细胞系对放射线治疗的影响，以人卵巢癌细胞株A2780及其紫杉醇耐药株A2780/Taxol为研究对象，以MTT法检测细胞的药物敏感性并评判分析细胞放射敏感性；克隆形成实验分析细胞放射抗拒性；实时荧光定量PCR分析照射前后细胞耐药基因MDR1的变化。实验结果显示：A2780／Taxol的耐药指数为43．96；随着放射剂量增大，A2780细胞和A2780／Taxol细胞的相对存活率明显下降，以A2780细胞明显（p〈0．05）；A2780细胞及其耐药A2780／Taxol细胞仇值分别为4．90和6．06，D0越大，放射抗拒性越强，表明耐药A2780／Taxol细胞的放射抗性强于A2780细胞（p〈0．01）；照射前及不同剂量照射作用后，耐药基因MDR1在A2780／Taxol细胞中的表达均明显高于A2780细胞（p=0．000）。这些结果揭示耐药卵巢癌细胞株A2780／Taxol对辐射具有耐受性，表明卵巢癌细胞系具有放化疗交叉耐受性，并且射线和药物诱导卵巢癌细胞耐药基因MDR1的过表达，可能是引起放化疗交叉耐受性的原因之一。

英文摘要：

In order to study the effect of drug resistance on the radiosensitivity of human ovarian cancer lines exposed to ^60Co y-rays at low absorbed doses, the human ovarian cancer cell line A2780 and its paclitaxel （PTX）-resistant subline A2780/Taxol were used as a model of the cells. MTT assay was used to determine the sensitivity of the cells to paclitaxel and radiation. Radioresistance of cells was calculated by colony formation test. The real time PCR was used to determine the variation in the expression of mRNA of MDR1 in the model ceils before and after radiation. It has been found that the resistance index （RI） of A2780/Taxol cells is up to 43.96, while the relative survival rate of A2780 ceils is more significant than that of 2780/Taxol cells with increment of radiation absorbed dose （p〈0.05）. The results indicate that the PTX-resistant cell line A2780/Taxol has significant radio-resistance. Drug and irradiation can induce over expression of MDR1, which may be one of the main reasons of crossed resistance to chemotherapy and radiotherapy in human ovarian cancer.