中文摘要：

目的研究南强菌素（DM）对肿瘤细胞紫杉醇耐药性的逆转作用并探讨其逆转机制。方法MTT法检测南强菌素对A549／T耐药细胞与A549敏感细胞的毒性及其对紫杉醇敏感性的影响，以AnnexinV法检测细胞凋亡率和Rh123在耐药细胞中的积累，HPLC测定细胞内紫杉醇的蓄积量，Westernblotting检测Ⅲ型β微管蛋白的表达水平。结果南强菌素可显著提高A549／T细胞对紫杉醇的敏感性，增加紫杉醇诱导耐药细胞凋亡率，增强A549／T细胞中紫杉醇和Rhl23的蓄积能力，同时，亦可明显抑制A549／T细胞中Ⅲ型β微管蛋白的表达水平。结论南强菌素可有效提高耐药细胞对紫杉醇的敏感性，逆转A549／T细胞对紫杉醇的耐药作用，其逆转机制可能与南强菌素抑制耐药肿瘤细胞膜上耐药蛋白β-糖蛋白的外泵转运功能和干扰Ⅲ型β微管蛋白的表达水平有关。

英文摘要：

Objective To investigate the effect and mechanism of deacetyl-mycoepoxydiene （DM） on reversing resist- ance to taxol in tumor cells. Methods MTT colorimetric assay was employed to evaluate the cytotoxicity of DM to sensitive tumor cells A549 and drug resistant cells A549/T. The influence of DM on cellular taxol sensitivity was analyzed as well. The reversal fold was approximated by MTT, and the apoptotic percentage was estimated in AnnexinV method. The accumulation of Rh123 in drug-resistance cells was observed by flow cell cytometry （FCM）. Additionally, the content of taxol and the expression of III-β-tubulin protein were respectively quantified by high performance liquid chromatography （HPLC） and Western blotting. Results This study demonstrated that DM enhanced the cellular taxol sensitivity and thus increased the apoptotic percentage of taxol-resistant tumor ceils. The content of taxol and Rh123 was greatly increased in DM-treated A549/T cells. Moreover, Western blotting results showed that DM inhibited the expression of III-β-tubulin protein in A549/T cells. Conclusion DM can effectively reverse the multidrug resistance and increase the drug sensitivity of tumor cells, which may function by interfering the expression of III-βtubulin protien and/or inhibiting the drug-resistant P-glyco-protein-mediated efflux pump on the cell membrane.