Butylated hydroxyanisole regulates ARE-mediated gene expression via Nrf2 coupled with ERK and JNK signaling pathway in HepG2 cells.
Many natural and synthetic cancer chemopreventive compounds are potent inducers of phase II detoxifying and antioxidant stress responsive genes. The phase II/antioxidant gene expression plays critical role in chemoprevention of carcinogenesis. The antioxidant responsive element (ARE), located on many phase II/antioxidant genes, binds with the transcription factor Nrf2, and is required for the activation of these phase II/antioxidant gene expression induced by many natural and synthetic cancer chemopreventive compounds. In this study, we investigated the potential roles of extracellular signal-regulated kinase (ERK) and c-jun N-terminal kinase (JNK) in the regulation of butylated hydroxyanisole (BHA)-induced and Nrf2-dependent ARE transcriptional activity and ARE-mediated endogenous heme oxygenase-1 (HO-1) protein expression in HepG2 cells. ARE transcriptional activity and HO-1 protein expression were increased dose dependently after treatment with BHA in HepG2 cells. Dose-response and time-course experiments showed that BHA increased the accumulation of Nrf2, and concomitantly decreased the protein level of Keap1. We next examined the phosphorylation of the MAPKs, and found that BHA significantly increased the phosphorylation levels of ERK1/2 and JNK1/2. Importantly BHA-induced ARE transcriptional activity was attenuated by the inhibition of ERK and JNK signaling using biochemical inhibitors and their dominant-negative mutants. Using confocal microscopy technique, treatment with BHA showed the release of Nrf2 sequestered by Keap1 in the cytosol, and that Nrf2 translocated into the nucleus. Importantly, cDNA transfections of ERK and JNK signaling pathways similarly released Nrf2 from Keap1 cytosolic sequestration and translocating Nrf2 into the nucleus. Taken together, these results strongly suggested that ERK and JNK signaling pathways played important and positive roles in BHA-induced and Nrf2-dependent regulation of ARE-mediated gene expression, as well as the nuclear translocation of Nrf2 in HepG2 cells.
Yuan
Xiaoling
X
Department of Pharmaceutics, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA.
Xu
Changjiang
C
Pan
Zui
Z
Keum
Young-Sam
YS
Kim
Jung-Hwan
JH
Shen
Guoxiang
G
Yu
Siwang
S
Oo
Khor Tin
KT
Ma
Jianjie
J
Kong
Ah-Ng Tony
AN
D015153:Blotting, Western; D002070:Butadienes / Q000494:pharmacology; D002083:Butylated Hydroxyanisole / Q000494:pharmacology*; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics; D000072019:Kelch-Like ECH-Associated Protein 1; D048670:MAP Kinase Kinase 4 / Q000378:metabolism*; D020935:MAP Kinase Signaling System; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D051267:NF-E2-Related Factor 2 / Q000378:metabolism*; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation
D002070:Butadienes; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; C431364:KEAP1 protein, human; D000072019:Kelch-Like ECH-Associated Protein 1; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D009570:Nitriles; C113580:U 0126; D002083:Butylated Hydroxyanisole; D048049:Extracellular Signal-Regulated MAP Kinases; D048670:MAP Kinase Kinase 4