Expression And Significance Of GCS Gene In Human Doxorubicin-resistant MCF-7/ADR Cells

Objective: To investigate the expression and significance of glucosylceramide synthase (GCS) gene in human MCF-7/ADR (doxorubicin-resistant) breast cancer cells and the parent MCF-7 cells;and to explore the relationship of experssion level and funcion between GCS and P-glycoprotein (P-gp).Methods: Exposing MCF-7/ADR cells to various concentrations (5μmol/L,10μmol/L,20μmol/L ) of PDMP for different time (24h&48h), MTT assay was used to assess the drug resistance of MCF-7/ADR cells, the inhibition ratio and IC50 of MCF-7 and MCF-7/ADR to doxorubicin whether they were pretreated by D,L-threo-1-phenyl-2-decanoyl-amino-3 -morpholino-1-propanol (PDMP) or not; FCM was employed to determine the expression of GCS protein and P-glycoprotein in MCF-7,MCF-7/ADR or the cells pretreated with PDMP; and to measure the fluorescence intensity in MCF-7/ADR cells after they were pretreated with different concentrations of PDMP for 48h; Real time RT-PCR was adopted to evaluate the expression of GCS mRNA in them.Results: The drug resistance of MCF-7/ADR was 22.69 times, PDMP exposure enhanced the inhibition ratio of doxorubicin to MCF-7/ADR, and the IC50 decreased homologously;GCS and P-gp expressed in both cells and their expression was significantly increased compared MCF-7/ADR cells to MCF-7 by FCM or real time RT-PCR (P<0.001). PDMP exposure degraded and the expression of GCS mRNA and its protein level (P<0.05), but showed no evident influence on P-gp. It manifested that doxorubicin intensity was reinforced in MCF-7/ADR after pretreatment with PDMP for 48h.Conclusions: GCS,expressing in human breast cancer cells, may take part in the development of malignant tumor and play an important role in the multidrug resistance of MCF-7/ADR, and it has some correlation with P-gp. PDMP has no influence on the protein level of P-gp, but it can impact its function to some extent.