title: Evidence of cell damage induced by major components of a diet-compatible mixture of oxysterols in human colon cancer CaCo-2 cell line.
abstract: Cholesterol oxidation products, termed oxysterols, have been shown to be more reactive than unoxidized cholesterol, possessing marked pro-inflammatory and cytotoxic effects in a number of cells and tissues. Oxysterols, absorbed with the diet as products of cholesterol auto-oxidation, have recently been suggested to potentially interfere with homeostasis of the mucosal intestinal epithelium, by promoting and sustaining irreversible damage. However, the treatment of colon cancer cells with a diet-compatible mixture of oxysterols does not elicit the same responses than individual components added to the cells at the same concentrations at which they are present in the mixture. Sixty μM oxysterol mixture showed a slight pro-apoptotic effect on human colon cancer CaCo-2 cell line, evaluated in terms of caspase-3 and caspase-7 activation; conversely, 7α-hydroxycholesterol, 7β-hydroxycholesterol and 5α,6α-epoxycholesterol were identified to be able to induce a significant pro-apoptotic effect if added to cell culture singly; 7β-hydroxycholesterol had stronger action than other compounds. The enhanced production of reactive oxygen species through up-regulation of the colonic NADPH-oxidase isoform NOX1 appeared to be the key event in oxysterol-induced apoptosis in these colon cancer cells. As regards pro-inflammatory effects of oxysterols, IL-8 and MCP-1 were evaluated for their chemotactic activity. Only MCP-1 production was significantly induced by 7β-hydroxycholesterol, as well as by cholesterol and oxysterol mixture. However, oxysterol-induced inflammation appeared to be NOX1-independent, suggesting a secondary role of this enzyme in inducing inflammation in colon cancer cells. A selective cell death induced by specific oxysterols against colon cancer cells, mainly exploiting their ability to activate NOX1 in generating oxidative reactions, might represent a promising field of investigation in colorectal cancer, and might bring new insights on strategies in anticancer therapy.
authors.affiliation: Department of Clinical and Biological Sciences, University of Turin, San Luigi Gonzaga Hospital, Orbassano, Turin, Italy.
authors.forename: Fiorella
authors.initials: F
authors.lastname: Biasi
authors.forename: Elena
authors.initials: E
authors.lastname: Chiarpotto
authors.forename: Barbara
authors.initials: B
authors.lastname: Sottero
authors.forename: Marco
authors.initials: M
authors.lastname: Maina
authors.forename: Cinzia
authors.initials: C
authors.lastname: Mascia
authors.forename: Tina
authors.initials: T
authors.lastname: Guina
authors.forename: Paola
authors.initials: P
authors.lastname: Gamba
authors.forename: Simona
authors.initials: S
authors.lastname: Gargiulo
authors.forename: Gabriella
authors.initials: G
authors.lastname: Testa
authors.forename: Gabriella
authors.initials: G
authors.lastname: Leonarduzzi
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Poli
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D018938:Caco-2 Cells; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002784:Cholesterol / Q000737:chemistry* / Q000494:pharmacology*; D002791:Cholesterol, Dietary / Q000494:pharmacology*; D003110:Colonic Neoplasms / Q000473:pathology*; D004305:Dose-Response Relationship, Drug; D006706:Homeostasis / Q000187:drug effects; D006801:Humans; D010084:Oxidation-Reduction
chemical_list: D002791:Cholesterol, Dietary; D002784:Cholesterol