| Objective:Prostate cancer is the second most frequent cancer diagnosis made in men and the fifth leading cause of death worldwide.Docetaxel(DOC)as a taxane is the first chemotherapy agent that has been used for more than fifteen years and showed improvement in overall survival in metastatic castration?resistant prostate cancer.Therefore,the new strategies for the combination chemotherapy with docetaxel are urgently needed.Silver nanoparticles(Ag NPs)have unique cytotoxic properties and can induce apoptosis of various cancer cells.The purpose of this study was to investigate whether the combination of Ag NPs and DOC could exert synergistic cytotoxic effects in the prostate cancer cells.Method:In this study,androgen-independent prostate cancer cell lines C42 and PC3 were chosen under the treatment of Ag Nps and DOC.Using MTT proliferation experiments,the dose-dependent proliferation curves of these two cell lines on DOC and Ag Nps were obtained.After selecting the appropriate concentration combination by the MTT experiment,we used flow cytometry to detect the effect of combined treatment on the apoptosis and cycle of prostate cancer cells compared with the single treatment.At the same time,we performed whole-transcriptome sequencing(RNA-seq)and analysis of untreated,DOC and Ag Nps treated PC3 cells individually and the combination.By analyzing the differentially expressed genes between the groups,we found the key genes that changed after combined treatment.We injected PC3 cells into the armpits of the nude mice.When the tumor formed,the mice were then randomly assigned to the different group,the untreatment group,the Ag Nps and DOC single treatment group and the combined treatment group.Nude mice were given intraperitoneal injections of Ag Nps and DOC each 4 days,and the tumors were removed after 4 times injection.Result:Our results showed the combined treatment with Ag NPs and DOC can significantly inhibited the viability and proliferation in C42 and PC3 prostate cancer cell lines.The percentage of apoptosis cells were significantly higher in combined treatment,compared with those cells treated with Ag NPs or DOC alone.The protein levels of Bcl-2,survivin and NF-κB were decreased dramatically,whereas cleaved-caspase-9 and cleaved-caspase-3 increased significantly compared with single treatment of Ag NPs or DOC.In addition to the investigation of apoptosis related factors,our data showed that the combined treatment enhanced the cell cycle arrest at the G2/M phase.The protein expression level of CDK1,CDK2,CDK4 and cyclin A2,the regulators of cell cycles,are decreased,which were detected by western blot analysis.By using the transcriptome sequencing technology(RNA-seq)to analyze differential genes expression in different treatment groups of PC3 cells.We found that compared with Ag Nps and DOC alone,the m RNA expression of GDF15 increased significantly after combined exposure.According to the method of Western Blot protein detection,we also verified the expression of GDF15 and the changes of related molecules in the Smad signaling pathway and non-Smad signaling pathway downstream of GDF15.After establishing a tumor-bearing experimental model in mice,we found that compared with nude mice intraperitoneally injected with Ag Nps or DOC alone,the volume of subcutaneously implanted tumors and the tumor-forming ability of nude mice were significantly decreased when they received the combined treatment of Ag Nps and DOC.Conclusion:Our data suggest that the combined treatment with DOC and Ag NPs exhibit higher apoptotic activity and cell cycle phase arrest in prostate cancer cells,compared with that induced by either of these agents alone.Moreover,RNA-seq was used to further explore the differential expression genes at the transcription level in the combined treatment.Together,our study could provide evidence that the combined treatment with Ag NPs and DOC,caused synergistic effect of cytotoxicity and apoptosis in C42 and PC3 prostate cancer cells.This approach can provide a new strategy for the treatment of castration-resistant prostate cancer. |
