Synergistic Mediation of Sulforaphane and Vitamin D on the Wnt-signaling Pathway

Colorectal cancer is a leading cause of death in The United States. Research suggests that colorectal cancer is strongly associated with aberrant expression of the Wnt-signaling pathway. Sulforaphane (SFN) is a bioactive component found in broccoli and is a histone deacetylase inhibitor that may play a role in regulation of the Wnt-signaling pathway. Binding of vitamin D to its receptor activates the vitamin D receptor element, which in turn enhances recruitment of histone acetylation factors. The present study investigated the synergistic effect of SFN and vitamin D on the Wnt-signaling pathway. We hypothesized that synergistic treatment using both compounds would show greater down-regulation of the Wnt-signaling pathway than treatment with either compound on its own. Caco-2 cells were harvested using treatments of various concentrations of SFN supplemented with and without vitamin D. Histone deacetylase inhibitor TSA was used as a positive control. RNA was isolated from cells and used to prepare cDNA. Quantitative real-time PCR was performed to assess expression of Wnt-pathway targeting genes Axin2, Cyclin D1, and C-Myc relative to the expression of housekeeping gene GAPDH. Our results reveal a trend indicating that as vitamin D treatment is supplemented with increasing concentrations of SFN, expression of Wnt-pathway-related genes is increasingly repressed. These findings represent preliminary data that warrant further investigation of SFN and vitamin D epigenetic regulation of the Wnt-signaling pathway.­­ Journal of Nature and Science, 1(2):e36, 2015.