Objective: The aim of this study was to investigate the possible synergistic effect of curcumin on the anticancer features of gemcitabine on prostate cancer cells. Material and Method: The human prostate adenocarcinoma cell line LNCaP was used in the studies. The effect of the co-administration of gemcitabine and curcumin on the viability of LNCaP cells was investigated by the WST-1 assay. Autophagy, ubiquitin-proteasome system (UPS), unfolded protein response (UPR) and cell death-associated proteins, androgenic signaling, proto-oncogenic, angiogenic and epithelial-mesenchymal transition (EMT) associated protein levels were investigated by immunoblotting studies. Result and Discussion: Our results showed that curcumin potentiated the anticancer effects of gemcitabine on LNCaP cells. Co-administration of curcumin and gemcitabine strengthened the suppressive effect of gemcitabine on cell viability. Moreover, co-administration modulated the autophagy, more strongly stimulated UPS and UPR, suppressed androgenic signaling, led to the activation of cell death-related poly [ADP-ribose] polymerase 1 (PARP-1) and caspase-3 and strongly suppressed the expression levels of proto-oncogenic c-Myc and angiogenic vascular endothelial growth factor-A (VEGF-A). In addition, it was determined that co-administration negatively regulated EMT by stimulating E-cadherin expression and suppressing N-cadherin level. These results suggest that the combined usage of gemcitabine and curcumin may offer a potent therapeutic approach to prostate cancer by enhancing the anticancer effects of gemcitabine.