Targeting Apoptotic Activity Against Prostate Cancer Stem Cells

Numerous data suggest that an increase of cancer stem cells (CSCs) in tumor mass can be the reason for failure of conventional therapies because of their resistance. CD44+/CD24- cells are a putative cancer stem cells subpopulation in prostate cancer. TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) is an activator of apoptosis in tumor cells. However, some tumors are TRAIL-resistant. Cancer cells can be re-sensitized to TRAIL induced apoptosis by a combination of TRAIL and taxanes. The aim of this work was to analyze the enhancement of the anticancer effect of TRAIL by paclitaxel, cabazitaxel and docetaxel in the whole population of PC3 and DU145 prostate cancer cells, but also in CD44+/CD24- prostate cancer stem cells. We examined the apoptotic effect of TRAIL and taxanes using flow cytometry and Annexin-V-PE staining. The co-treatment with taxanes and TRAIL enhanced significantly the apoptosis in CD44+/CD24- cells only in PC3 cell line but not in DU145 cells. We discovered also that taxanes can increase the expression of death receptor TRAIL-R2 in PC3 prostate cancer cells. The results of our study show that treatment with paclitaxel, cabazitaxel and docetaxel is able to enhance the apoptosis induced by TRAIL even in prostate cancer stem cells.