中文摘要：

目的体外建立人肺腺癌细胞多药耐药细胞系，观察其生物学特性并探讨其细胞内DNA polβ和多药耐药基因mdrl、mrpl、GST-π、lrp和topo Ⅱ的表达及意义。方法以紫杉醇为诱导药，采用间歇逐步增加剂量法建立人肺腺癌多药耐药细胞系A549／TXL20；MTT法检测A549／TXL20对紫杉醇、顺铂、长春新碱、5-氟尿嘧啶和丝裂霉素的耐药指数（RF）；细胞克隆形成法测定A549／TXL20对紫杉醇的敏感性；高效液相色谱测定细胞内紫杉醇的浓度；RT-PCR法测定人肺腺癌多药耐药细胞系A549／TXL20中DNA polβ、mdrl、GST-π、mrpl、lrp和topoⅡ的基因表达。站杲①A549／TXL20形态不规则，较亲本细胞略小，核／浆比增加，倍增时间没有明显变化；②A549／TXL20对紫杉醇的RF为19．3，对顺铂的RF为67．4，对长春新碱、5-氟尿嘧啶、丝裂霉素和顺铂等抗癌药物有不同程度的耐药性；③A549／TXL20对紫杉醇的敏感性降低，其紫杉醇的含量较亲本细胞下降；④A549／TXL20细胞中 DNA polβ、mdrl、GST-π、mrpl、lrp的基因表达量分别较A549细胞中的表达量明显增加，差异具有统计学意义（P〈0．05）。站论建立了相对稳定的人肺腺癌多药耐药细胞系A549／TXL20，其耐药机制可能与mdrl、GST-π、mrpl、lrp和DNA polβ基因的高表达有关。

英文摘要：

To establish human lung adenocarcinoma multidrug resistance cell lines in vitro, observe their biological characteristics, and investigate the mRNA expressions of DNA polfβ, mdr 1, mrpl, GST-π, lrp and topo Ⅱ genes. Methods Paclitaxel-resistant cell lines （A549/TXL20） were established in vitro by exposure to stepwise increased concentrations of the drug in a cell culture medium. Biological morphology and cell cycles were analyzed by morphometry and flow cytometry. The chemoresistance indexes of cells were measured by methyl tetrazolium assay. Evaluation of growth and in vitro drug sensitivity were performed. RT-PCR was employed to analyze the mRNA expressions of the DNA polβ, mdr 1, mrpl, GST-π, lrp, and topo II genes. Results （i） Compared with parent cells, the resistant sublines had a lower confluent density. They were smaller and mixed with giant cells in different sizes and with different numbers of nucleoli, and the growth property of A549/TXL20 did not change significantly compared with A549 cell lines. ② The resistant cells, A549/TXL20, were 19.3 times more resistant to paclitaxel and 67.4 times more resistant to cisplatin than the parent cells, and also demonstrated cross-resistance to mitomycin, vinblastine, and 5-fluouracil （5-FU）. （3） Compared with the A549 celllines, an unreasonably higher level of drug resistance and lower drug concentration was detected in A549/TXL20 cells after exposure to the drug in the culture medium. O The mRNA expression level of DNA polβ, mdrl, GST- π, mrpl andlrp genes in A549/TXL20 cells was significantly higher than that in A549 cell lines （P〈0.05）. Conclusion The A549/TXL20 cell lines may be used as an experimental system for the search for a means to overcome drug resistance and elucidate possible mechanism of acquired MDR involved in human lung adenocarcinoma. The formation of mutltidrug resistance of A549/TXL20 cell lines may have relation to the overexpressions of DNA polβ, mdrl, GST- π, mrpl and lrp genes.