钙调素拮抗剂O-(4-乙氧基)-丁基-小檗胺增强阿霉素杀伤MCF-7/ADR细胞的机制研究

目的研究钙调素拮抗剂0-4-乙氧基-丁基-小檗胺(EBB)增强阿霉素诱导乳腺癌多药耐药细胞系MCF-7/ADR细胞的杀伤作用及其相关机制。方法用MTT法测定阿霉素、EBB单独及联合用药对阿霉素杀伤乳腺癌多药耐药细胞系(MCF-7/ADR)及其亲代细胞系(MCF-7)的作用的IC50值,用不同浓度EBB处理MCF-7/ADR细胞后用FACS法分析EBB对阿霉素诱导细胞凋亡及对mdr1mRNA和P-gp蛋白水平表达的影响,通过激光共聚焦显微镜观察EBB处理前后及用EBB预处理24和48h后MCF-7/ADR和MCF-7细胞内阿霉素浓度的改变。结果MTT结果显示EBB对MCF-7和MCF-7/ADR都具有抗肿瘤活性;EBB还能协同提高阿霉素的细胞毒作用,MCF-7组两药相互作用指数(CDI)值为0.73,MCF-7/ADR组CDI值为0.49,其对耐药细胞的协同作用更为明显。随EBB剂量增加,低剂量阿霉素诱导MCF-7/ADR细胞凋亡增加而且P-gp蛋白表达水平逐渐下降,细胞内阿霉素浓度逐渐提高,而且用EBB预处理MCF-7/ADR细胞24和48h后细胞内阿霉素和罗丹明浓度也逐渐提高。结论EBB是有效的肿瘤细胞化疗药物,它不但能直接抑制P-gp功能还具有下调P-gp蛋白表达的作用,从而有效逆转MCF-7/ADR细胞的耐药现象,协同增强化疗药物对耐药细胞的杀伤作用。

Mechanism of synergistic antitumor effects of EBB and doxorubicin on multidrug resistant MCF-7/ADR

Aim To study the mechanism of synergistic antitumor of EBB and doxorubicin in doxorubicin-resistant MCF-7/ADR breast carcinoma cells.Methods The antitumor activity of doxorubiein alone and its combination with EBB were measured by MTT assay in MCF-7/ADR and MCF-7cells. The rate of doxorubicin-induced apoptosis and the protein and mRNA levels of P-glycoprotein(P-gp) were determined in MCF-7/ADR treated with EBB by flow cytometry (FACS), respectively.Laser scanning confocal microscopy was used to detect the intracellular accumulation of drug in EBB-treated MCF-7 and MCF-7/ADR cells.Results EBB had antitumor effects for MCF-7 and MCF-7/ADR.It could potentiate the antitumor effect of dororubicin with CDI of 0.73 and 0.49 for MCF-7 and MCF-7/ADR,respectively.EBB and doxorubicin acted synergistically in elevating apoptosis of MCF-7/ADR and downregulating the expression of P-gp in a dose-dependent manner in MCF-7/ADR.EBB restored the intracellular accumulation of doxorubicin in MCF-7/ADR cells in a dose-dependent manner.After pretreatment with EBB for 24 h and 48 h,the intracellular accumulation of doxorubicin and Rh123 was obviousely restored in MCF-7/ADR cells compared with control in a time-dependent manner.Conclusion EBB is a potential agent which has strong inhibitory effect on both multidrug resistant cells and their parental cells.EBB can significantly potentiate the antitumor effects of dororubicin in MCF-7/ADR cells by blocking the function of P-glycoprotein and inhibiting the expression of P-glycoprotein.