title: Quercetin modulates Nrf2 and glutathione-related defenses in HepG2 cells: Involvement of p38.
abstract: Dietary flavonoid quercetin has been suggested as a cancer chemopreventive agent, but the mechanisms of action remain unclear. This study investigated the influence of quercetin on p38-MAPK and the potential regulation of the nuclear transcription factor erythroid-2p45-related factor (Nrf2) and the cellular antioxidant/detoxifying defense system related to glutathione (GSH) by p38 in HepG2 cells. Incubation of HepG2 cells with quercetin at a range of concentrations (5-50μM) for 4 or 18h induced a differential effect on the modulation of p38 and Nrf2 in HepG2 cells, 50μM quercetin showed the highest activation of p38 at 4h of treatment and values of p38 similar to those of control cells after 18 h of incubation, together with the inhibition of Nrf2 at both incubation times. Quercetin (50μM) induced a time-dependent activation of p38, which was in concert with a transient stimulation of Nrf2 to provoke its inhibition afterward. Quercetin also increased GSH content, mRNA levels of glutamylcysteine-synthetase (GCS) and expression and/or activity of glutathione-peroxidase, glutathione-reductase and GCS after 4h of incubation, and glutathione-S-transferase after 18h of exposure. Further studies with the p38 specific inhibitor SB203580 showed that the p38 blockage restored the inhibited Nrf2 transcription factor and the enzymatic expression and activity of antioxidant/detoxificant enzymes after 4h exposure. In conclusion, p38-MAPK is involved in the mechanisms of the cell response to quercetin through the modulation of Nrf2 and glutathione-related enzymes in HepG2 cells.
authors.affiliation: Department of Metabolism and Nutrition, Institute of Food Science, Technology and Nutrition-ICTAN (Former Instituto del Frío), Consejo Superior de Investigaciones Científicas (CSIC), José Antonio Novais 10, Ciudad Universitaria, Madrid, Spain.
authors.forename: Ana Belén
authors.initials: AB
authors.lastname: Granado-Serrano
authors.forename: María Angeles
authors.initials: MA
authors.lastname: Martín
authors.forename: Laura
authors.initials: L
authors.lastname: Bravo
authors.forename: Luis
authors.initials: L
authors.lastname: Goya
authors.forename: Sonia
authors.initials: S
authors.lastname: Ramos
mesh_terms: D016588:Anticarcinogenic Agents / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D005721:Glutamate-Cysteine Ligase / Q000378:metabolism; D005978:Glutathione / Q000031:analogs & derivatives / Q000378:metabolism*; D005979:Glutathione Peroxidase / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D056945:Hep G2 Cells; D018197:Hepatoblastoma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D051267:NF-E2-Related Factor 2 / Q000378:metabolism*; D011794:Quercetin / Q000494:pharmacology*; D013997:Time Factors; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D016588:Anticarcinogenic Agents; D000975:Antioxidants; D051267:NF-E2-Related Factor 2; D011794:Quercetin; D005979:Glutathione Peroxidase; D005980:Glutathione Reductase; D005982:Glutathione Transferase; D048051:p38 Mitogen-Activated Protein Kinases; D005721:Glutamate-Cysteine Ligase; D005978:Glutathione