Identification of proteins responsible for the multiple drug resistance in 5-fluorouracil-induced breast cancer cell using proteomics analysis

This study aimed to explore the mechanism of multi-drug resistance (MDR) in 5-fluorouracil (5-FU)-induced breast cancer cell MCF-7. MCF-7 cells were exposed in stepwise escalating concentration of 5-FU to develop the resistant cell line, MCF-7/5-FU. Biological and molecular characteristics of the cells were studied through MTT, flow cytometry, real-time PCR, western-blot, and the global protein profiles between MCF-7/5-FU and parental MCF-7 were compared using proteomic approach. Then some of the differentially expressed proteins were validated by western-blot. In addition, the role of 14-3-3 sigma was validated using gene transfection. Drug resistance of MCF-7/5-FU cells to 5-FU, MX, cDDP, ADM, TAXOL all increased significantly compared with MCF-7 cells and that maybe related to BCRP, but not MDR1 and MRP1. Differentially expressed proteins between MCF-7/5-FU and MCF-7 cells were identified; 12 proteins were up-regulated and 18 proteins were down-regulated in MCF-7/5-FU cells. Expressive levels of some proteins in western-blot validation were consistent with the results in proteomic analysis. Enforced 14-3-3 sigma expression can increase the sensitivity of MCF-7/5-FU cells to 5-FU and cDDP. MDR of MCF-7/5-FU likely associated with differentially expressed proteins and 14-3-3 sigma may play a positive role in chemotherapy. These findings may provide theoretical support for the prediction of chemotherapeutic response and reverse of MDR.