title: Function of DNA methyltransferase 3a in lead (Pb(2+) )-Induced Cyclooxygenase-2 gene.
abstract: Lead ions (Pb(2+) ) are toxic industrial pollutants associated with chronic inflammatory diseases in humans and animals. Previously, we found that Pb(2+) ions induce COX-2 gene expression via the EGF receptor/nuclear factor-κB signal transduction pathway in epidermoid carcinoma cell line A431. In this study, to see whether Pb(2+) ions affect COX-2 expression by epigenetic mechanisms, we looked at the mRNAs of DNA methyltransferases (DNMTs) using real-time PCR of total RNA from these cells. Cells exposed to Pb(2+) had low levels of DNMT3a mRNA, whereas the levels of DNMT1 and DNMT3b mRNAs remained unchanged. Pretreatment of cells with DNMT inhibitor 5-aza-2'-deoxycytidine (5 μM) followed by Pb(2+) (1 μM) significantly increased levels of COX-2 mRNA compared with cells treated with Pb(2+) alone. Overexpression of tumor suppressor gene Rb correlated with an increase in COX-2 mRNA and a decrease in DNMT3a mRNA. Conversely, overexpression of transcription factor E2F1 correlated with a decrease in COX-2 mRNA and an increase in DMNT3a mRNA. Pretreatment with EGFR inhibitors AG1478 and PD153035 significantly limited Pb(2+) -induced reduction in DNMT3a mRNA. In addition, gene knockdown of DNMT3a with short hairpin RNA correlated with increased COX-2 mRNA induced by Pb(2+) . Our findings suggest Pb(2+) ions induce COX-2 expression indirectly by reducing DNMT3a methylation of the COX-2 promoter via transcription factors Rb and E2F1.
authors.affiliation: Department of Clinical Pharmacy, School of Pharmacy, Taipei Medical University, Taipei, Taiwan.
authors.forename: Yao-Ting
authors.initials: YT
authors.lastname: Tsai
authors.affiliation: Department of Clinical Pharmacy, School of Pharmacy, Taipei Medical University, Taipei, Taiwan.
authors.forename: Che-Mai
authors.initials: CM
authors.lastname: Chang
authors.affiliation: Cancer Center, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.|Division of Gastrointestinal and General Surgery, Department of Surgery, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.|Graduate Institute of Clinical Medicine, College of Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Jaw-Yuan
authors.initials: JY
authors.lastname: Wang
authors.affiliation: Cancer Center, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.|Division of Gastrointestinal and General Surgery, Department of Surgery, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.|Graduate Institute of Clinical Medicine, College of Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.|Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Ming-Feng
authors.initials: MF
authors.lastname: Hou
authors.affiliation: Institute of Bioinformatics and Biosignal Transduction, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan.|Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Ju-Ming
authors.initials: JM
authors.lastname: Wang
authors.affiliation: Integrative Bioscience and Biomedical Engineering, Graduate School of Science and Engineering, Waseda University, Tokyo, Japan.
authors.forename: Robert
authors.initials: R
authors.lastname: Shiurba
authors.affiliation: Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Wen-Chang
authors.initials: WC
authors.lastname: Chang
authors.affiliation: Department of Clinical Pharmacy, School of Pharmacy, Taipei Medical University, Taipei, Taiwan.|Cancer Center, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.|Department of Pharmacy, Taipei Medical University-Wanfang Hospital, Taipei, Taiwan.|Master Program for Clinical Pharmacogenomics and Pharmacoproteomics, School of Pharmacy, Taipei Medical University, Taipei, Taiwan.
authors.forename: Wei-Chiao
authors.initials: WC
authors.lastname: Chang
mesh_terms: D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D045744:Cell Line, Tumor; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism*; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D019175:DNA Methylation / Q000187:drug effects; D000090205:DNA Methyltransferase 3A; D000077209:Decitabine; D050687:E2F1 Transcription Factor / Q000235:genetics / Q000378:metabolism; D004785:Environmental Pollutants / Q000633:toxicity*; D006801:Humans; D007854:Lead / Q000633:toxicity*; D016328:NF-kappa B / Q000378:metabolism; D011401:Promoter Regions, Genetic; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D059467:Transcriptome / Q000187:drug effects*; D000097584:DNA Methyltransferase 3B
chemical_list: D001374:Azacitidine; D051546:Cyclooxygenase 2; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; D000090205:DNA Methyltransferase 3A; D000077209:Decitabine; D050687:E2F1 Transcription Factor; D004785:Environmental Pollutants; D007854:Lead; D016328:NF-kappa B; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D000097584:DNA Methyltransferase 3B; C000717967:DNMT3A protein, human; C000619380:DNMT1 protein, human
keywords: DNA methyltransferase 3a; cyclooxygenase-2; epidermal growth factor receptor; lead