Abstract LB-271: Inulin inhibits free radical species in HCT 116 adenoma carcinoma and normal human HK (keratinocyte) cell line

Abstract

Background: Bile acids have been implicated in oxidative damage via stimulation of reactive species including superoxide and nitric oxide. Superoxide and nitric oxide production are associated with inflammation. NF-κB up- regulation provides a critical link between inflammation and cancer. It has also been shown that there is a possible correlation between total activity of nitric oxide synthase and p53 mutation frequency in lung adenocarcinoma. Inulin is an oligosaccharide, classified as a prebiotic, and shown to improve gut health when used in combination with probiotics. However, there is paucity of data on how prebiotics alone affect gut health and by which mechanism of action. Objectives: To evaluate the potential of inulin in reduction of reactive species and its mechanism of inhibiting cancer cells. Methods: HCT116 adenocarcinoma cells were treated with inulin at different concentrations and stopped at various time ranges (30 minutes - 24 hours). Modified Greiss reagent was used in the study of reactive nitrogen species (RNS). Nitro blue tetrazolium (NBT) assay (Modified), was used in the investigation of superoxide production (SOP) in HCT116 in the presence of deoxycholic acids (DC); a secondary bile acids. Inulin (5%-40%) significantly inhibited DC (100μM-500 μM), generated RNS in HCT 116 cell lines (p<0.05; n = 6). The impact of inulin on RNS was observed to be dose and time-dependent. DC 100μM-300μM was observed to stimulate SOP in HCT116 (p<0.05; n = 3). Inulin (30%) was observed to inhibit SOP in HCT116 (P<0.05). The impact of inulin on RS was not enhanced in the presence of probiotics. Probiotic (Bifidobacterium longum) inhibited nitric oxide production (p<0.05; n = 3).The proliferation (Cyquant assay) of HCT116 was observed to be significantly influenced in the presence of DC; proliferation is inversely proportional to the concentration of DC; 100μM (p<0.05; n = 3) Proliferation of HCT 116 is enhanced in the presence of low concentration of DC <150 μM, while cell death and morphological change into mesenchymal cells is enhanced with >DC150μM. 30% Inulin enhanced cell death of morphologically changed cells in the presence of DC >150μM, with complete cell death occurring at DC300μM.Inulin inhibits proliferation of HCT 116 cancer cells. Inulin inhibits nitric oxide induced by DC p<0.05(n = 3) in normal human HK (keratinocytes) cells. Conclusions: Peroxynitrite is formed by nitric oxide and superoxide; and considered to be cytotoxic, causing DNA damage and leading to carcinogenesis via inactivation of tumour suppressor oncoprotein p53. Possible mechanism of action by which inulin could exert protective effect on colon cells could be via its antioxidant effect. Further work is underway investigating the effect of inulin and bile-acid on NF-κB, p53 and apoptosis in adenocarcinoma and normal dermal HK epithelial cells. Citation Format: Bene Akromaa Ekine-Afolabi, Sandra Appiah, Azra Pachenari, Lucy Ghali. Inulin inhibits free radical species in HCT 116 adenoma carcinoma and normal human HK (keratinocyte) cell line. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-271. doi:10.1158/1538-7445.AM2015-LB-271