Genomic and proteomic analysis of chemoresistance in breast cancer cell lines: MCF-7 and MDA-MB-231

Official URL: http://192.168.1.20/record=b1304378 (Table of Contents)

In this study, cisplatin-resistant adenocarcinoma breast cancer cell lines, labeled MCF-7/R6 and MDA-MB-231/R2 were established by 6 replicative sequential treatment of low doses (1 micromolar) over high doses (30 micromolar) of cisplatin and chemoresistance was evaluated as apoptotic response to 30 micromolar cisplatin for 48 hours. Throughout the study parental cells were used as control. RNA was isolated to conduct microarray study to analyze 48000 gene probes (Illumina Human WG-6 BeadChip). Gene expression data was analyzed by MATLAB 2009 and identification of differentially expressed genes were further studied by proteomic analysis to understand the drug resistance mechanisms. Our data indicated that transcription of drug resistant marker genes, such as GSTP1 and ABCB6 were upregulated in MCF-7/R6 cell line. Both intrinsically resistant cell line: MDA-MB-231 and acquired resistant cell line: MCF-7/R6 were similar in activating NF- kappa-B pathway but not MAP kinase pathway. In MCF-7/R6 cell line NF-kappa-B pathway was transactivated through p50 subunit, as well as translocation of Foxo3a transcription factor into the nucleus. Genes responsible for cell death, Foxo family and MAPK levels were found to change significantly at protein and genetic level in MCF-7/R6 and MDA-MB-231/R2 cells. Phosphorylation levels in transcription factor Foxo1 and Foxo3a were found to change MCF-7/R6 cells, indicating resistance to apoptosis. Moreover, cell cycle, tumor suppressor and estrogen receptor levels were found to be altered in MCF-7/R6 cell line. Our data clearly identify several proteins and pathways which have distinct roles in chemoresistance mechanism. This knowledge can be further validated in a clinical setting.