title: Regulation of liver fatty acid binding protein expression by clofibrate in hepatoma cells.
abstract: Peroxisome proliferator-activated receptor (PPAR) agonists such as clofibrate are known to affect liver fatty acid binding protein (L-FABP) levels, which in turn influence hepatocellular oxidant status. The mechanism of clofibrate's modulation of L-FABP levels is not clear. In this study we used clofibrate (PPARα agonist), MK886 (PPARα antagonist), and GW9662 (PPARγ antagonist) in determining the regulating mechanism of L-FABP expression and its antioxidant activity in CRL-1548 hepatoma cells. Antioxidant activity was assessed by determining intracellular reactive oxygen species (ROS) using dichlorofluorescein (DCF) fluorescence. The effect of clofibrate on cytosolic activity of the intracellular antioxidant enzymes was also assessed. RT-PCR and mRNA stability assay showed that clofibrate treatment enhanced L-FABP mRNA stability, which resulted in increased L-FABP levels. A nuclear run-off assay and RT-PCR measurements of L-FABP mRNA revealed that clofibrate increased the L-FABP gene transcription rate. The increased L-FABP was associated with reduced cytosolic ROS. Levels of superoxide dismutase, glutathione peroxidase, and catalase were not affected by clofibrate treatment. L-FABP siRNA knockdown studies showed that a reduction in L-FABP expression was associated with increased DCF fluorescence. We conclude that clofibrate enhanced L-FABP gene transcription and mRNA stability, thus affecting L-FABP expression and ultimately cellular antioxidant activity.
authors.affiliation: Faculty of Pharmacy, University of Manitoba, Winnipeg, MB, Canada.
authors.forename: Jing
authors.initials: J
authors.lastname: Yan
authors.forename: Yuewen
authors.initials: Y
authors.lastname: Gong
authors.forename: Guqi
authors.initials: G
authors.lastname: Wang
authors.forename: Yu
authors.initials: Y
authors.lastname: Gong
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Burczynski
mesh_terms: D000813:Anilides / Q000494:pharmacology; D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy / Q000201:enzymology; D002374:Catalase / Q000032:analysis / Q000378:metabolism; D045744:Cell Line, Tumor; D002994:Clofibrate / Q000494:pharmacology; D050556:Fatty Acid-Binding Proteins / Q000032:analysis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D005452:Fluoresceins / Q000032:analysis; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D005979:Glutathione Peroxidase / Q000032:analysis / Q000378:metabolism; D022781:Hepatocytes / Q000187:drug effects / Q000201:enzymology; D006801:Humans; D006861:Hydrogen Peroxide / Q000008:administration & dosage; D007211:Indoles / Q000494:pharmacology; D008113:Liver Neoplasms / Q000188:drug therapy / Q000201:enzymology; D018384:Oxidative Stress; D047493:PPAR alpha / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D020871:RNA Stability / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D013482:Superoxide Dismutase / Q000032:analysis / Q000378:metabolism; D002722:Chlorobenzenes
chemical_list: D000813:Anilides; D002374:Catalase; D002994:Clofibrate; D050556:Fatty Acid-Binding Proteins; D005452:Fluoresceins; D005979:Glutathione Peroxidase; D006861:Hydrogen Peroxide; D007211:Indoles; D047493:PPAR alpha; D012333:RNA, Messenger; D013482:Superoxide Dismutase; C457499:2-chloro-5-nitrobenzanilide; C060893:MK-886; D002722:Chlorobenzenes; C037631:2',7'-dichlorofluorescein