Naringin sensitizes human prostate cancer cells to paclitaxel therapy

BACKGROUND: The aim of the study was to evaluate whether the use of chemotherapy in combination with naringin, a dietary plant polyphenolic flavonoid, could enhance the therapeutic efficacy of paclitaxel treatment in human prostate cancer (PCa) cells. MATERIALS AND METHODS: DU145, PC3, and LNCaP cells were treated with various concentrations of paclitaxel, naringin, and their combinations. Methylthiazolyldiphenyl-tetrazolium bromide (MTT), image-based cytometer, quantitative reverse transcription PCR (RT-qPCR), Western blot, and transwell assay were used to evaluate cell viability, apoptosis and cell cycle, the mRNA expression, protein expression, and cell migration, respectively. RESULTS: Naringin treatment inhibited cell survival in a dose- and time-dependent manner by inducing apoptosis and cell cycle arrest in G1 phase. Among the pathways evaluated, naringin (150 μM) significantly induced the mRNA expressions of BAX, BID, caspase 3, cytochrome c, p53, p21(Cip1), and p27(Kip1) and downregulated the expressions of survivin and livin in DU145 cells. The combination of naringin and paclitaxel treatments synergistically increased the cytotoxic effects of paclitaxel in androgen-independent DU145 and PC3 cells, as well as in androgen-sensitive LNCaP cells. The combination of naringin with docetaxel has almost the same inhibitory effect on cell proliferation as the paclitaxel combination in androgen-independent cells, whereas there is no similar effect in LNCaP cells. Naringin exhibits significant inhibitory effects on the cell migration ability. The flavonoid either alone or in combination with paclitaxel therapy resulted in an increase in tumor suppressor PTEN (phosphatase and tensin homolog deleted on chromosome 10) protein expression and decrease in nuclear factor-κB p50 protein level in DU145 cells. CONCLUSION: In conclusion, naringin acts as a chemosensitizer which synergistically strengths the cytotoxic effect of paclitaxel in PCa cells. Therefore, naringin therapy alone or in combination with paclitaxel may be useful in the treatment of PCa. However, there is a need for more detailed in vivo studies of the mechanism of action.