Breast carcinoma is the most common malignancy in women. The progression of tumor is associated with overexpression of inhibitors of apoptosis proteins (IAPs) such as survivin and multidrug resistant P-glycoprotein (P-gp). PI3K/Akt pathway is involved in cell cycle progression, apoptosis and neoplastic transformation. PI3K/Akt has been shown to regulate survivin in breast cancer. The aim of this study was to investigate the expression of survivin and P-gp, the modulation of survivin by P-gp in PI3K/Akt during the progression of drug resistance (MDR) in MCF-7 breast cancer cells and adriamycin (ADR)-resistant MCF-7/ADR cells. The expression of survivin and P-gp in MCF-7/ADR cells were higher than that of the MCF-7 cells using RT-PCR and Western blot analysis. Survivin transcription was associated with P-glycoprotein/MDR1 overexpression using promoter activity analysis. LY294002, specific inhibitor of PI3K could suppress survivin and P-gp expression, decreased survivin promoter activity and enhanced cell sensitivity to drugs. This study shows survivin transcription was associated with P-glycoprotein/MDR1 overexpression, PI3k/Akt pathway was involved in P-glycoprotein/MDR1 associated survivin transcription activity in the multidrug resistant MCF-7 breast cancer cells.

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