Resveratrol improves the anticancer effects of doxorubicin in vitro and in vivo models: A mechanistic insight

Background: Resveratrol (RSVL), a well known dietary compound and in combination with doxorubicin (DOX) has gained a global importance for cancer prevention. However, mechanism of action by this combination is not well understood till date. Hypothesis: The synergistic combination of RSVL and DOX might be more effective in anti-cancer activity by modulating the diverse cancer signaling pathways as compared to their alone treatments. Methods: The cytotoxicity of alone and combination doses of RSVL and DOX were analyzed by colorimetric MTT(3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) cell proliferation assay. The migration and colony forming abilities were evaluated by wound healing and clonogenic assays. Apoptosis was detected by Annexin V/PI and DAPI stainings. The cell cycle and intracellular reactive oxygen species (ROS) generation were measured by flow cytometry. The differential expression of genes and proteins were measured by qRT-PCR and western blotting analyses. Finally, in-vivo studies were performed in Ehrlich ascitic carcinoma (EAC) mouse model. Results: The synergistic combination of DOX (IC20) and RSVL (IC30) was selected based on the combination index values in MCF-7 and MDA-MB-231 cell lines. This combination showed potent growth inhibition with similar to 2.5 fold of dose advantage and also significantly decreased the wound healing and clonogenic potential of breast cancer cells. The combination treatment was also found to inhibit the inflammatory response (NF-kappa B, COX-2), autophagic flux (LC3, Beclin-1), redox regulation (Nrf2) and induces apoptosis (BAX: BCL-2 ratio and Caspase-9) in breast cancer cells. Further, combined dosages of DOX (5 mg/kg b.wt) and RSVL (10 mg/kg b.wt) inhibited tumor volume with increased life span (139%, p value < 0.05) in Ehrlich ascitic carcinoma (EAC) cells bearing mice. Conclusion: In brief, our results suggested that resveratrol chemosensitizes doxorubicin in combination, through inhibiting breast cancer cells proliferation and invasion, and inducing apoptosis via suppression of chronic inflammation and autophagy. (C) 2016 Elsevier GmbH. All rights reserved.