Classical and Non-Classical Compound Combinations for Treatment of Prostate Cancer Cell Line PC3 ^†

Abstract

Prostate cancer is one of the leading causes of death among men. Our study focuses on seeking new compounds and combinations to diminish the severe side effects of classical anticancer drugs for treating this type of cancer. In this study, we investigated and compared the classical anticancer drug docetaxel and non-classical compounds, Au porphyrin, and the plant lectin jacalin, and in different combinations on the prostate cancer cell line PC3. Jacalin, isolated from jackfruit seeds by affinity chromatography on immobilized galactose, specifically recognizes the tumor-associated Thomsen–Friedenreich antigen. The present investigation shows the interaction of jacalin with Au porphyrin, registering conformational changes within the protein due to the binding. From the titration curve, the affinity of 1.8 ± 0.39 µM for the jacalin—Au porphyrin complex was calculated. In vitro experiments with PC3 cells treated with docetaxel, Au porphyrin, jacalin and combinations indicated a decrease in cell viability. The IC₅₀ for Au porphyrin and for docetaxel were studied and indicated that the calculated IC₅₀ for docetaxel was 8 orders of magnitude higher than that for Au porphyrin. Interestingly, we found that jacalin-Au porphyrin complex is more cytotoxic reaching cell viability of 34%, than docetaxel-Au-porphyrin complex (with cell viability above 50%). Our results demonstrate the effects of three compounds as well as the effects of their combinations upon PC3 cells. Interestingly, low concentrations of the plant lectin jacalin (3 µM) facilitated the cell cytotoxicity of Au-porphyrin, showing new perspectives in cancer treatment.