Abstract: Objective To observe the phenomenon of epithelial-mesenchymal transition(EMT) and expression of P-glucoprotein(P-GP) in MCF-7 cells, induced by SNAIL, and reveal the effection of EMT enhance drug-resistance capacity of MCR-7 cells. Methods Constructed eukaryotic expression vector of SNAIL; and then transfected into MCF-7 cells. Expression of epithelial marker E-cadherin and interstitial marker Vimentin detected by immunofluorescence; drug resistance to adriamycin(ADM) was measured by MTT; expression of P-GP and SNAIL was detected by flow cytometry; SNAIL, E-cadherin, Vimentin and MDR1 mRNA were evaluated by Real-Time-PCR. Results Compared with parental MCF-7 cells, expression of E-cadherin decreased obviously, while Vimentin get up(P＜0.01); drug resistance to ADM and expression of SNAIL, P-GP increased too(P＜0.01), consistent with results of Real-Time-PCR. Conclusions EMT, induced by SNAIL, can enhance the drug-resistance capacity to ADM, mediated by P-GP, in breast cancer cell.

Key words: breast cancer, MDR, EMT, Snail, P-gp