Fig. 6

Gamma-secretase inhibitor (GSI) significantly increases the sensitivity of chemoresistant cells to paclitaxel. a Western blotting analysis of the expression of Notch-1, Akt, glycogen synthase kinase-3β (GSK-3β), phosphorylated GSK-3β (p-GSK-3β), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) p65, and β-actin in parental, chemoresistant, control vector-transfected, and E-cadherin-overexpressing PCa cells. b qPCR analysis of Notch-1 expression in the above mentioned cells. c qPCR analysis of Notch-1 expression in E-cadherin-silenced PCa cells. d Notch-1 expression is inhibited by GSI. Cells were treated with GSI (0, 5, 10, 20 µmol/L) for 72 h. The protein levels of Notch-1, Notch-2, and Notch-4 were assayed using Western blotting. e GSI does not inhibit the proliferation of PC3-TxR and DU145-TxR cells. Cells were treated with GSI (20 μmol/L), and cell survival was determined using MTS assay. f GSI reverses chemoresistance of PCa cells to paclitaxel. PC3-TxR and DU145-TxR cells were incubated with or without 20 µmol/L GSI in the presence of paclitaxel for 72 h. Cell survival was determined using MTS assay. The mean ± SEM values of data from 3 independent experiments are presented. *P < 0.05, **P < 0.01