人乳腺癌耐药细胞株中GCS表达及其与P-gp的关系

Expression of GCS in human doxorubicin-resistant breast cancer cells and its relationship with P-gp

目的探讨葡萄糖神经酰胺合成酶(GCS)在人乳腺癌细胞多药耐药中的作用及其与P-糖蛋白(P-gp)的关系。方法采用MTT法检测阿霉素对人乳腺癌耐药细胞株MCF-7/Adr和敏感株MCF-7的抑制率和半数抑制浓度(IC50);用浓度为5、10和20μmol/L的GCS抑制剂(PDMP)预处理MCF-7/ADR24h和48h后检测IC50;用流式细胞检测术检测MCF-7及PDMP预处理MCF-7/ADR前后GCS蛋白、P-gp的表达和细胞中ADM的荧光强度。结果MCF-7/Adr对MCF-7的耐药倍数为22.69倍,PDMP作用后阿霉素对MCF-7/Adr的抑制率升高,IC50下降(P<0.05);MCF-7/Adr中GCS和P-gp的表达均高于MCF-7;PDMP使MCF-7/Adr中GCS表达下降(P<0.05),对P-gp表达无明显影响(P>0.05)。PDMP可使阿霉素在MCF-7内潴留增多。结论GCS可能参与肿瘤耐药的发生过程,并在MCF-7/Adr多药耐药中起重要作用;PDMP能影响P-gp功能,GCS与P-gp有一定关系。

Objective To investigate the effect of glucosylceramide synthase （GGS） on the multidrug resistance of MCF-7/Adr and the relationship between GCS and P glycoprotein（P-gp）. Methods Exposing MCF 7/ADR to various concentrations （5. 10 and 20 μmol/L） of PDMP for different time periods（24 and 48 h）, MTT was used to detect the drug resistance of MCF 7/ADR cells,tile median inhibitory concentration（ IC50 ）of MCF-7 and MCF-7/ADR to doxorubicin whether they were pretreatcd by PDMP or not. Flow cytometry （FCM） was used to test the expression of GCS and Pgp on MCF7, MCF 7/Adr and MCF 7/Adr after pretreatcd with PDMP （D, Lthreo-l-phenyl- 2 decanoyl-amino-3-nlorpholincrl-propanol）. The data of mean fluorescent intensity of adriamycin inside MCF-7/Adr was obtained by FCM. Results The drug resistance of MCF 7/Adr cells was about 23 times higher than that of MCF7. Pretreatment with PDMP could sensitize MCFT/Adr to adriamycin. The expressions of GCS and P-gp on MCF-7/Adr were stronger than those on MCF-7. PI）MP could make the expression of GCS on MCF-7/ADR become weaker, but had no significant influence on the expression of P-gp. PDMP could enhance adriamycin retention inside MCF 7/Adr. Conclusion GCS may lake part in the development and exert important function in multidrug resistance of MCF-7/Adr. PDMP can influence the function of Pgp and GCS is relatively related to P-gp.