Arsenite stimulates cyclooxygenase-2 expression through activating IkappaB kinase and nuclear factor kappaB in primary and ECV304 endothelial cells.
Epidemiological studies have shown that chronic exposure to arsenic can result in liver injury, peripheral neuropathy, arteriosclerosis, and an increased incidence of cancer of the lung, skin, bladder, and liver. The overexpression of inducible cyclooxygenase-2 (Cox-2) has been associated with vascular inflammation and cellular proliferation. However, the effect of arsenite on Cox-2 gene expression in endothelial cells was left to be investigated. Western Blot analysis of HUVECs revealed a two-fold induction of Cox-2 protein by arsenite. This induction was associated with a two-fold increase of prostaglandin E2 in the media. Furthermore, the level of Cox-2 mRNA was correspondingly elevated as demonstrated by both Northern blot and reverse transcriptase-polymerase chain reaction (RT-PCR) analyses. Transfection of an immortalized human endothelium cell line (ECV304) with Cox-2 reporter gene constructs demonstrated that the transcription of Cox-2 gene was enhanced by arsenite. This induction was attenuated by pyrrolidine dithiocarbamate (PDTC), an inhibitor of NFkappaB. In addition, electrophoretic mobility shift assays indicated that NFkappaB activity was induced by arsenite. The kinase activity assay also indicated that IkappaB kinase (IKK) activity was induced by arsenite. These findings indicated that the induction of Cox-2 gene transcription by arsenite was through the stimulation of NFkappaB activity. Arsenite could induce IKK activity, which leads to the phosphorylation and degradation of IkappaB in ECV304 cells. Therefore, it appears that IKK signaling pathway is involved in arsenite-mediated Cox-2 expression.
Tsai
Shu-Huei
SH
Department of Orthopaedics and Traumatology, School of Medicine, Taipei Medical University Hospital, Taipei Medical University, Taipei, Taiwan. clare@tmc.edu.tw
Liang
Yu-Chih
YC
Chen
Linda
L
Ho
Feng-Ming
FM
Hsieh
Ming-Shium
MS
Lin
Jen-Kun
JK
D000975:Antioxidants / Q000494:pharmacology; D018053:Arsenites / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D002478:Cells, Cultured; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000096:biosynthesis; D004347:Drug Interactions; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism*; D007527:Isoenzymes / Q000096:biosynthesis* / Q000235:genetics; D008156:Luciferases / Q000096:biosynthesis / Q000235:genetics; D008565:Membrane Proteins; D016328:NF-kappa B / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000187:drug effects; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis* / Q000235:genetics; D011759:Pyrrolidines / Q000494:pharmacology; D013859:Thiocarbamates / Q000494:pharmacology; D014471:Umbilical Veins
D000975:Antioxidants; D018053:Arsenites; D020672:I-kappa B Proteins; D007527:Isoenzymes; D008565:Membrane Proteins; D016328:NF-kappa B; D011759:Pyrrolidines; D013859:Thiocarbamates; C020972:pyrrolidine dithiocarbamic acid; D008156:Luciferases; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D015232:Dinoprostone; C015001:arsenite