NADPH oxidase NOX5-S mediates acid-induced cyclooxygenase-2 expression via activation of NF-kappaB in Barrett's esophageal adenocarcinoma cells.
We have shown that the NADPH oxidase NOX5-S may play an important role in the progression from Barrett's esophagus to esophageal adenocarcinoma (EA) by increasing cell proliferation and decreasing apoptosis. However, the mechanism of the acid-induced NOX5-S-mediated increase in cell proliferation is not known. We found that, in SEG1 EA cells, the acid-induced increase in prostaglandin E2 (PGE2) production was mediated by activation of cyclooxygenase-2 (COX2) but not by COX1. Acid treatment increased intracellular Ca2+, and a blockade of intracellular Ca2+ increase inhibited the acid-induced increase in COX2 expression and PGE2 production. Knockdown of NOX5-S or NF-kappaB1 p50 by their small interfering RNA significantly inhibited acid-induced COX2 expression and PGE2 production in SEG1 cells. Acid treatment significantly decreased IkappaBalpha and increased luciferase activity when SEG1 cells were transfected with an NF-kappaB in vivo activation reporter plasmid, pNF-kappaB-Luc. In a novel Barrett's cell line overexpressing NOX5-S, IkappaBalpha was significantly reduced, and luciferase activity increased when these Barrett's cells were transfected with pNF-kappaB-Luc. Overexpression of NOX5-S in Barrett's cells significantly increased H2O2 production, COX2 expression, PGE2 production, and thymidine incorporation. The increase in thymidine incorporation occurring in NOX5-S-overexpressing Barrett's cells or induced by acid treatment in SEG1 EA cells was significantly decreased by COX2 inhibitors or small interfering RNA. We conclude that acid-induced COX2 expression and PGE2 production depend on an increase in cytosolic Ca2+ and sequential activation of NOX5-S and NF-kappaB in SEG1 cells. COX2-derived PGE2 production may contribute to NOX5-S-mediated cell proliferation in SEG1 cells.
Si
Jin
J
Department of Medicine, Rhode Island Hospital and Brown Medical School, Providence, Rhode Island 02903, USA.
Fu
Xiaoying
X
Behar
Jose
J
Wands
Jack
J
Beer
David G
DG
Souza
Rhonda F
RF
Spechler
Stuart J
SJ
Lambeth
David
D
Cao
Weibiao
W
D000230:Adenocarcinoma / Q000201:enzymology* / Q000235:genetics; D017209:Apoptosis / Q000235:genetics; D001471:Barrett Esophagus / Q000201:enzymology* / Q000235:genetics; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D051545:Cyclooxygenase 1 / Q000378:metabolism; D051546:Cyclooxygenase 2 / Q000096:biosynthesis* / Q000235:genetics; D015232:Dinoprostone / Q000096:biosynthesis; D004938:Esophageal Neoplasms / Q000201:enzymology* / Q000235:genetics; D015870:Gene Expression; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D020672:I-kappa B Proteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*; D000074664:NADPH Oxidase 5; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism*; D000072000:NF-KappaB Inhibitor alpha; D052002:NF-kappa B p50 Subunit / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics
D020672:I-kappa B Proteins; D008565:Membrane Proteins; D052002:NF-kappa B p50 Subunit; C000606204:NFKBIA protein, human; D009363:Neoplasm Proteins; D034741:RNA, Small Interfering; D000072000:NF-KappaB Inhibitor alpha; D006861:Hydrogen Peroxide; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; C496511:PTGS1 protein, human; C496540:PTGS2 protein, human; D000074664:NADPH Oxidase 5; D019255:NADPH Oxidases; C431571:NOX5 protein, human; D015232:Dinoprostone; D002118:Calcium