title: Riboflavin depletion of intestinal cells in vitro leads to impaired energy generation and enhanced oxidative stress.
abstract: BACKGROUND
  Riboflavin is an essential component of the human diet, with an established role for its derivative cofactors in oxidative metabolism. Our previous in vivo data suggest that riboflavin may act as a signalling molecule in the intestinal lumen, regulating crypt development and cell turnover. Our in vitro studies in riboflavin-depleted intestinal cells in culture indicate that riboflavin depletion impairs normal mitosis.
  
  
  METHODS
  The aim of the study was to establish an improved intestinal cell model of riboflavin depletion using the structural analogue of riboflavin, lumiflavin (7,8,10-trimethyl-isoalloxazine) and to determine effects on cell function. The study was conducted using three intestinal cell lines, Caco-2, HCT116 and HT29 cells.
  
  
  RESULTS
  Cell growth was inhibited in all three cell lines, in a lumiflavin concentration-dependent manner. Riboflavin depletion was confirmed through a significant decrease in intracellular riboflavin concentrations in Caco-2 and HT29 cell lines and a significant increase in the activation coefficient for the flavin adenine dinucleotide-dependent enzyme glutathione reductase. Riboflavin depletion led to a significant reduction in intracellular ATP concentration, and an enhanced generation of reactive oxygen species was also observed in response to riboflavin depletion, in all cell lines; effects were at least fivefold greater in Caco-2 cells than other cells. Riboflavin-depleted Caco-2 and HCT116 cells also showed an irreversible loss of proliferative potential.
  
  
  CONCLUSIONS
  A model system of intracellular riboflavin depletion in intestinal epithelial cells has been developed. Riboflavin depletion induced by lumiflavin results in oxidative stress and a disruption of energy generation, which may contribute to observed effects on cell proliferation.
authors.affiliation: Human Nutrition Unit, Department of Oncology, Faculty of Medicine, Dentistry and Health, University of Sheffield, Sheffield, UK.
authors.forename: Eun-Sook
authors.initials: ES
authors.lastname: Lee
authors.forename: Bernard M
authors.initials: BM
authors.lastname: Corfe
authors.forename: Hilary J
authors.initials: HJ
authors.lastname: Powers
mesh_terms: D001692:Biological Transport; D018938:Caco-2 Cells; D049109:Cell Proliferation; D004734:Energy Metabolism; D005415:Flavins / Q000494:pharmacology*; D005980:Glutathione Reductase / Q000378:metabolism; D045325:HCT116 Cells; D019073:HT29 Cells; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000166:cytology*; D018384:Oxidative Stress / Q000187:drug effects*; D017382:Reactive Oxygen Species / Q000378:metabolism; D012256:Riboflavin / Q000378:metabolism*
chemical_list: D005415:Flavins; D017382:Reactive Oxygen Species; C001922:lumiflavin; D005980:Glutathione Reductase; D012256:Riboflavin