The Study Of Synergetic Effect Of Celastrol On Docetaxel In Prostate Cancer Cells

Prostate cancer is one male disease with high incidence and death rates. Although with the upcoming prognostic methods and diverse treatments springing up, the life span of most patients will be dramatically shortened with the formation of CRPC and drug resistant feature. CRPC is reported to be regulated by AR pathway, the reactivation of which is critical for tumor survival. AR-V7 can be translocated to the nucleus and regulate according genes without androgen, and yet has been the hotspot in CRPC treatment.Docetaxel, the first-line chemotherapy medicine for CRPC treatment, can induce cell apoptosis and inhibit AR translocation via tubulin stabilization. However, tumors will inevitably develop to be drug resistant, which derives from the shift in apoptosis pathway and the AR-V7 expression in prostate cancer cells. As the natural proteasome inhibitor, celastrol causes PCa cells growth inhibition through apoptosis and AR down regulation. Thus, we have AR-V7 positive cell line 22Rv1 as our model, in contrast with AR-V7 negative cell line LNCaP in our research, aiming at the co-treatment effect of docetaxel and celastrol on prostate cancer cell lines and its mechanism.In this research, 22Rv1 has been confirmed as a docetaxel resistant cell line via MTT assay, while LNCa P is a docetaxel sensitive cell line. Meanwhile, cell survival rates after docetaxel and celastrol co-treatment are similar in LNCa P and 22Rv1. The co-treatment efficacy calculation indicates that celastrol can resensitize 22Rv1 to docetaxel. On the contrary, celastrol antagonizes docetaxel in LNCa P cell line.Through FITC apoptosis assay, the apoptotic rates between LNCa P and 22Rv1 under either single medicine treatment, namely docetaxel 0.5 n M and 0.8 μM, are quite similar. Whereas the apoptotic rate is 32.6% in LNCa P, it raises abruptly up to 50.62% in 22Rv1, which demonstrates that celastrol can recover the apoptosis breakdown in docetaxel resistance cell line. Meanwhile cleaved PARP has been upregulated in celastrol treated 22Rv1, which is rarely detected in docetaxel treated setting. Those evidences direct to a point that celastrol re-sensitize 22Rv1 to docetaxel in a way of reactivating apoptosis. q RT-PCR assay has shown that celastrol, not docetaxel can down-regulate AR and AR-V7 expression, resulting in inhibiting AR pathway and cell survival failure.In conclusion, this research has furthered the co-treatment study of docetaxel and celastrol on prostate cancer cell lines, clarified part of mechanisms on how celastrol inhibits AR-V7 positive cell line proliferation, and sensitize it to docetaxel.