Establishment and characterization of a docetaxel-resistant human prostate cancer cell line.

The aim of the present study was to establish a novel docetaxel-resistant prostate cancer cell line and investigate its biological characteristics. The human prostate cell line, PC-3, was exposed to docetaxel, the concentrations of which were increased in a stepwise manner in the medium to select the drug-resistant cell line, PC-3/DTX. The morphological features were observed using inverted microscopy. The growth curves of PC-3 and PC-3/DTX cells were drawn to calculate the doubling time. Flow cytometry was performed to determine cell-cycle distribution. A 3-(4,5-dimethyl-2-thiazol)-2,5-diphenyl-2H tetrazolium bromide assay was performed to test the drug resistance of PC-3 and PC-3/DTX cells. Western blot analysis was conducted to determine the protein expression levels of the mammalian target of rapamycin (mTOR) signaling pathway, which may serve a role in regulating drug resistance in the two cell lines. PC-3/DTX cells exhibited changes in morphology, proliferation rate, doubling time and cell-cycle distributions, compared with PC-3 cells. PC-3/DTX cells were 10.9-fold resistant to docetaxel in comparison with PC-3 cells. The results showed that PC-3/DTX cells overexpressed Rictor and p-AKT(S473) proteins, which are specific subunits or downstream substrates of mTORC2. The new findings suggested that the mTORC2 signaling pathway may serve an important role in the regulation of docetaxel drug resistance of PC-3 cells. In conclusion, PC-3/DTX cells may be applied to study the resistance of anticancer drugs and to identify methods to overcome resistance.