Regulation of carcinogenesis and modulation through Wnt/β-catenin signaling by curcumin in an ovarian cancer cell line

The secreted frizzled-related protein 5 gene (SFRP5) that antagonize the Wnt/beta-catenin signaling is frequently inactivated by promoter methylation and oncogenic activation of the Wnt signaling pathway is common in many cancers. The curcumin-rich Curcuma longa has been reported to potent anti-cancer property involved in epigenetic regulation to inhibit tumor suppressor gene methylation and re-expression. In a compounds screening, we found that curcumin can inhibit Wnt/beta-catenin signaling. Therefore, the aim of this study was to investigate the effects of curcumin on SFRP5 DNA methylation modification in an ovarian cancer cell line (SKOV3). SKOV3 cells were treated with DMSO, 10 mu M 5-aza-2'-deoxycytidine (DAC), 5 mu M DAC, 20 mu M curcumin, and 20 mu M curcumin combined with 5 mu M DAC for 96 hours, following which RNA and proteins were extracted for further analysis. The results showed that curcumin combined with 5 mu M DAC may inhibit cancer cell colony formation, migration through EMT (epithelial-mesenchymal transition) process regulation, total DNMT activity, especially in DNMT3a protein expression, and may also regulate tumor suppressor gene SFRP5 expression involved in the Wnt/beta-catenin signaling pathway. The combined treatment attenuated ovarian cancer development.