title: Interactions between sulforaphane and apigenin in the induction of UGT1A1 and GSTA1 in CaCo-2 cells.
abstract: The isothiocyanate, sulforaphane and the flavonoid, apigenin modulate gene expression including phase II detoxifying enzymes, such as glutathione S-transferases (GST) and UDP-glucuronosyltransferases (UGT). Using undifferentiated CaCo-2 cells, we have examined the interactions between sulforaphane and apigenin in the regulation of UGT and GST expression. We show that apigenin induces UGT1A1 transcription (4-fold) but not GSTA1, and that sulforaphane induces both UGT1A1 (3.7-fold) and GSTA1 (2.8-fold) transcription in both dose- and time-dependent manners. The combination of sulforaphane and apigenin resulted in a synergistic induction of UGT1A1 mRNA up to 12-fold, although this interaction was not seen for GSTA1. Nuclear factor kappa B (NF-kappaB) mRNA was induced by apigenin and sulforaphane (2.5- and 2-fold, respectively). NF-kappaB translocation inhibitor SN50 and phosphatidylinositol 3-kinase (PI3) inhibitor LY294002 decreased the induction of GSTA1 by sulforaphane almost to baseline level. However, the MEK inhibitor PD98059 enhanced significantly the induction of GSTA1 by sulforaphane. This suggests that NF-kappaB and PI3-kinase signaling pathways play a role in GSTA1 gene expression. Conversely, the induction of UGT1A1 transcription by sulforaphane was totally abolished by PD98059, although PD98059 slightly enhanced (20%) the induction of UGT1A1 by apigenin implying that the induction of UGT1A1 by sulforaphane is mediated by MAPK/extracellular signal-regulated kinase kinase, whereas UGT1A1 induction by apigenin may be associated with NF-kappaB translocation since the NF-kappaB translocation inhibitor, SN50 enhanced the induction of UGT by apigenin. The results show that UGT1A1 and GSTA1 are regulated by sulforaphane through different signal transduction pathways and the differences in the mechanisms of modulation of UGT1A1 transcription by sulforaphane and apigenin resulted in a synergistic effect between these two compounds in the induction of UGT1A1.
authors.affiliation: Nutrition Division, Institute of Food Research, Norwich Research Park, Norwich NR4 7UA, UK.
authors.forename: Vanda
authors.initials: V
authors.lastname: Svehlíková
authors.forename: Shuran
authors.initials: S
authors.lastname: Wang
authors.forename: Jana
authors.initials: J
authors.lastname: Jakubíková
authors.forename: Gary
authors.initials: G
authors.lastname: Williamson
authors.forename: Richard
authors.initials: R
authors.lastname: Mithen
authors.forename: Yongping
authors.initials: Y
authors.lastname: Bao
mesh_terms: D000230:Adenocarcinoma / Q000201:enzymology* / Q000235:genetics; D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D047310:Apigenin; D001426:Bacterial Proteins; D018938:Caco-2 Cells; D002352:Carrier Proteins / Q000378:metabolism*; D003110:Colonic Neoplasms / Q000201:enzymology* / Q000235:genetics; D004347:Drug Interactions; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology*; D014453:Glucuronosyltransferase / Q000378:metabolism*; D005982:Glutathione Transferase; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D017879:Isothiocyanates; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors; D016328:NF-kappa B / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D015398:Signal Transduction; D016329:Sp1 Transcription Factor / Q000378:metabolism; D013454:Sulfoxides; D013861:Thiocyanates / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured
chemical_list: D016588:Anticarcinogenic Agents; D047310:Apigenin; D001426:Bacterial Proteins; D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D014453:Glucuronosyltransferase; D005982:Glutathione Transferase; D047908:Intracellular Signaling Peptides and Proteins; D017879:Isothiocyanates; D020929:Mitogen-Activated Protein Kinase Kinases; D016328:NF-kappa B; D019869:Phosphatidylinositol 3-Kinases; D016329:Sp1 Transcription Factor; D013454:Sulfoxides; D013861:Thiocyanates; C105760:GstA protein, bacteria; C484555:GSTA1 protein, human; C016766:sulforaphane