Abstract 5645: Growth inhibitory activity of ethanol extracts of Chinese and Brazilian propolis in human colon carcinoma cell lines

Abstract

Abstract Propolis is a natural product derived from plant resins collected by honeybees, and has been used globally as a folk medicine for centuries. More than 300 bio-active compounds have been identified from bee propolis. In the current study, we examined whether the ethanol extracts of Chinese and Brazilian propolis exert anticancer activities in four human colon carcinoma cell lines, CaCo2, HCT116, HT29 and SW480. Propolis samples were extracted with ethanol, and the crude extracts were dissolved in dimethylsulfoxide and used for the following experiments. We also examined the effects of the ethanol extract of Chinese propolis on cell proliferation, cell cycle progression, apoptosis, and the levels of expression of cell cycle control molecules in the HCT116 and HT29 cell lines. In the HCT116, HT29 and SW480 cell lines, the extracts of both Chinese and Brazilian propolis caused a marked dose-dependent growth inhibition, with IC50 values in the range of 4-41 μg/ml. In the FHC normal human colonic epithelial cell line, the extract of Chinese propolis failed to cause a marked growth inhibition, the growth inhibition rate was about 20%, whereas it was about 90% in the HCT116 and HT29 cell lines. In the HCT116 cell line, at concentrations of 10 and 20 μg/ml the extract of Chinese propolis caused a marked increase in sub-G1 fraction of cells in a dose-dependent fashion. The propolis extract (20 μg/ml) caused a significant increase of cells in sub-G1 and this increase was associated with a concomitant relative decrease of cells in the G1, S and G2-M phases of the cell cycle, indicating that Chinese propolis extract induced apoptosis in the HCT116 cell line. In addition, Chinese propolis extract caused a dose-dependent increase in the cellular mRNA levels of p21CIP1 and p53 in the HCT116 cell line. These findings indicate that the ethanol extracts of propolis contain components that may have anticancer activity. Thus, propolis and related products may provide a novel approach to the chemoprevention and/or chemotherapy of human colon carcinoma. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5645.