Oxidative stress and mitochondrial functions in the intestinal Caco-2/15 cell line.
BACKGROUND
Although mitochondrial dysfunction and oxidative stress are central mechanisms in various pathological conditions, they have not been extensively studied in the gastrointestinal tract, which is known to be constantly exposed to luminal oxidants from ingested foods. Key among these is the simultaneous consumption of iron salts and ascorbic acid, which can cause oxidative damage to biomolecules.


RESULTS
The objective of the present work was to evaluate how iron-ascorbate (FE/ASC)-mediated lipid peroxidation affects mitochondrion functioning in Caco-2/15 cells. Our results show that treatment of Caco-2/15 cells with FE/ASC (0.2 mM/2 mM) (1) increased malondialdehyde levels assessed by HPLC; (2) reduced ATP production noted by luminescence assay; (3) provoked dysregulation of mitochondrial calcium homeostasis as evidenced by confocal fluorescence microscopy; (4) upregulated the protein expression of cytochrome C and apoptotic inducing factor, indicating exaggerated apoptosis; (5) affected mitochondrial respiratory chain complexes I, II, III and IV; (6) elicited mtDNA lesions as illustrated by the raised levels of 8-OHdG; (7) lowered DNA glycosylase, one of the first lines of defense against 8-OHdG mutagenicity; and (8) altered the gene expression and protein mass of mitochondrial transcription factors (mtTFA, mtTFB1, mtTFB2) without any effects on RNA Polymerase. The presence of the powerful antioxidant BHT (50 microM) prevented the occurrence of oxidative stress and most of the mitochondrial abnormalities.


CONCLUSIONS
Collectively, our findings indicate that acute exposure of Caco-2/15 cells to FE/ASC-catalyzed peroxidation produces harmful effects on mitochondrial functions and DNA integrity, which are abrogated by the powerful exogenous BHT antioxidant. Functional derangements of mitochondria may have implications in oxidative stress-related disorders such as inflammatory bowel diseases.
Taha
Rame
R
Department of Nutrition, Research Center, CHU-Sainte-Justine, Université de Montréal, Montreal, Canada.
Seidman
Ernest
E
Mailhot
Genevieve
G
Boudreau
François
F
Gendron
Fernand-Pierre
FP
Beaulieu
Jean-François
JF
Ménard
Daniel
D
Delvin
Edgard
E
Amre
Devendra
D
Levy
Emile
E
D000255:Adenosine Triphosphate / Q000378:metabolism; D001205:Ascorbic Acid / Q000494:pharmacology; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D045744:Cell Line, Tumor; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D007501:Iron / Q000494:pharmacology; D015227:Lipid Peroxidation / Q000187:drug effects; D008315:Malondialdehyde / Q000378:metabolism; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D010085:Oxidative Phosphorylation / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D008315:Malondialdehyde; D000255:Adenosine Triphosphate; D007501:Iron; D001205:Ascorbic Acid; D002118:Calcium