The novel antioxidant 3-O-caffeoyl-1-methylquinic acid induces Nrf2-dependent phase II detoxifying genes and alters intracellular glutathione redox.
Induction of detoxifying phase II genes by chemopreventive agents represents a coordinated protective response against oxidative stress and neoplastic effects of carcinogens. We have earlier shown that a novel antioxidant from the bamboo leaves constituent 3-O-caffeoyl-1-methylquinic acid (MCGA3) induces heme oxygenase-1 (HO-1) and protects endothelial cells from ROS-induced endothelial injury. The purpose of this study was to elucidate the induction mechanism of HO-1 and other phase II genes by MCGA3 in human umbilical vascular endothelial cells (HUVECs). Using Northern blotting and RT-PCR, we found that treatment of HUVECs with MCGA3 increased, in a dose and time-dependent manner, steady-state mRNA levels of the selected phase II genes including HO-1, ferritin, gamma-glutamylcysteine lygase, glutathione reductase, and glutathione transferase, which were dependent on Nrf2 nuclear translocation. The observed phase II gene induction by MCGA3 was found to be associated with MCGA3-mediated cytoprotective activity, ROS-scavenging potency, and the increase in the cellular levels of both reduced (GSH) and oxidized glutathione (GSSG). Interestingly, exposure to MCGA3 resulted in a decreased ratio of GSH/GSSG, which was negatively related with mRNA level of phase II genes. By employing N-acetylcysteine and GSH biosynthetic enzyme inhibitors as well as prooxidants, hemin and H(2)O(2), we show that a decreased intracellular GSH/GSSG homeostasis, at least in part, may be involved in the MCGA3-mediated phase II gene induction and Nrf2 translocation, although the attenuation of HO-1 expression with SP 600125 supports a partial involvement of JNK signaling.
Kweon
Mee-Hyang
MH
Department of Dermatology, University of Wisconsin, Medical Science Center, Madison, 53706, USA.
In Park
Young
Y
Sung
Ha-Chin
HC
Mukhtar
Hasan
H
D000111:Acetylcysteine / Q000494:pharmacology; D021581:Active Transport, Cell Nucleus; D000975:Antioxidants / Q000494:pharmacology*; D002330:Carmustine / Q000494:pharmacology; D002478:Cells, Cultured; D003687:Dehydroepiandrosterone / Q000494:pharmacology; D005293:Ferritins / Q000378:metabolism; D005786:Gene Expression Regulation; D005978:Glutathione / Q000378:metabolism*; D051547:Heme Oxygenase-1 / Q000378:metabolism; D006801:Humans; D020935:MAP Kinase Signaling System; D050217:Metabolic Detoxication, Phase II / Q000235:genetics*; D051267:NF-E2-Related Factor 2 / Q000378:metabolism*; D010084:Oxidation-Reduction / Q000187:drug effects; D010766:Phosphorylation; D011801:Quinic Acid / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics; D013997:Time Factors; D015533:Transcriptional Activation; D014470:Umbilical Cord / Q000187:drug effects / Q000378:metabolism
C490257:3-O-caffeoyl-1-methylquinic acid; D000975:Antioxidants; D051267:NF-E2-Related Factor 2; D012333:RNA, Messenger; D011801:Quinic Acid; D003687:Dehydroepiandrosterone; D005293:Ferritins; D051547:Heme Oxygenase-1; D005978:Glutathione; D002330:Carmustine; D000111:Acetylcysteine