Abstract B47: A novel combination of Biochanin-A/ 5-Fluorouracil against colon cancer: Impact on Wnt/beta-catenin signaling

Abstract Giza, Egypt. Colon cancer is one of the most common types of cancer worldwide. It is considered the second leading cause of cancer deaths in both women and men combined. Although 5-fluorouracil (5FU) is the first line of therapy for colon cancer, its use is significantly hampered by drug toxicity and development of tumor resistance. Therefore, it is important to investigate strategies to overcome such stumbling block. Biochanin-A (Bio-A) is a promising natural isoflavone that has selective cytotoxicity against cancer cells. This study aimed at investigating the modulatory impact of Bio-A on 5FU cytotoxicity in colon cancer cells and exploring the possible underlying mechanisms with emphasis on Wnt/beta catenin signals. Cytotoxicity and Calcusyn synergy analyses were conducted to assess IC50 and synergism between Bio-A and 5FU in both Caco-2 and HCT-116 cell lines. The effect of the different treatments on Wnt/ β-catenin signals was assessed using phospho-tracer enzyme linked immunoassays. Bio-A alone showed cytotoxic activity against Caco-2 and HCT-116 colon cancer cells with IC50 values of 34.34 and 34.41 μM respectively using sulforhodamine-B cytotoxicity assay. Combined treatment of 5FU/ Bio-A at 1:2 and 1:4 ratios reduced the IC50 of 5FU significantly by 26.7 and 57% in Caco-2 cell line. The same treatments produced reduction of 5FU IC50 by 13.2 and 39.6% in HCT-116. Calcusyn® analysis indicated that the combinations were synergistic in both cell lines with combination index CI<1. Since Wnt/ β-catenin signaling plays an important role in the pathogenesis of colon cancer, the study was substantiated to investigate the effects of Bio-A and Bio-A/5FU combination on some key signals in addition to cell cycle analysis and assessment of cyclin D1 expression. Bio-A significantly suppressed Akt-phosphorylation and hence reduced GSK3β phosphorylation and preserved it in the active form. Hence, treatment with Bio-A boosted the ratio of phosphorylated β-catenin(p-S45)/total β-catenin indicating an increased degradation of β-catenin and reduced signaling. In conclusion, these results underscore the potential merit of Bio-A as an adjuvant to 5FU for the management of colon cancer. Further tumor xenograft studies are encouraged in order to verify this effect in vivo. Citation Format: Mohamed Mahmoud, Mohamed El-Sesy, Mai F. Tolba, Dalal A. Abou El Ella. A novel combination of Biochanin-A/ 5-Fluorouracil against colon cancer: Impact on Wnt/beta-catenin signaling. [abstract]. In: Proceedings of the AACR Special Conference on Translational Control of Cancer: A New Frontier in Cancer Biology and Therapy; 2016 Oct 27-30; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2017;77(6 Suppl):Abstract nr B47.