Role of a novel bile acid receptor TGR5 in the development of oesophageal adenocarcinoma.
OBJECTIVE
Mechanisms of the progression from Barrett's oesophagus to oesophageal adenocarcinoma (OA) are not fully understood. Bile acids may have an important role in this progression. This study aimed at examining the role of NADPH oxidase NOX5-S and a novel bile acid receptor TGR5 in taurodeoxycholic acid (TDCA)-induced increase in cell proliferation.


METHODS
Human Barrett's cell line BAR-T and OA cell line FLO were transfected by the Lipofectamine 2000 or Amaxa-Nucleofector-System. mRNAs were measured by real-time PCR. H(2)O(2) was measured by a fluorescent assay. Cell proliferation was determined by measurement of thymidine incorporation.


RESULTS
NOX5-S was present in FLO cells. TDCA significantly increased NOX5-S expression, H(2)O(2) production and thymidine incorporation in FLO and BAR-T cells. This increase in thymidine incorporation was significantly reduced by knockdown of NOX5-S. TGR5 mRNA and protein levels were significantly higher in OA tissues than in normal oesophageal mucosa or Barrett's mucosa. Knockdown of TGR5 markedly inhibited TDCA-induced increase in NOX5-S expression, H(2)O(2) production and thymidine incorporation in FLO and BAR-T cells. Overexpression of TGR5 significantly enhanced the effects of TDCA in FLO cells. TGR5 receptors were coupled with Galphaq and Galphai3 proteins, but only Galphaq mediated TDCA-induced increase in NOX5-S expression, H(2)O(2) production and thymidine incorporation in FLO cells.


CONCLUSIONS
TDCA-induced increase in cell proliferation depends on upregulation of NOX5-S expression in BAR-T and FLO cells. TDCA-induced NOX5-S expression may be mediated by activation of the TGR5 receptor and Galphaq protein. These data may provide potential targets to prevent and/or treat Barrett's OA.
Hong
Jie
J
Department of Medicine, Rhode Island Hospital and Warren Alpert Medical School of Brown University, Providence, Rhode Island 02903, USA.
Behar
Jose
J
Wands
Jack
J
Resnick
Murray
M
Wang
Li Juan
LJ
DeLellis
Ronald A
RA
Lambeth
David
D
Souza
Rhonda F
RF
Spechler
Stuart J
SJ
Cao
Weibiao
W
D000230:Adenocarcinoma / Q000209:etiology / Q000378:metabolism*; D002756:Cholagogues and Choleretics; D004938:Esophageal Neoplasms / Q000209:etiology / Q000378:metabolism*; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D055785:Gene Knockdown Techniques; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D000074664:NADPH Oxidase 5; D019255:NADPH Oxidases / Q000378:metabolism; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013657:Taurodeoxycholic Acid; D014407:Tumor Cells, Cultured
D002756:Cholagogues and Choleretics; C473772:GPBAR1 protein, human; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D043562:Receptors, G-Protein-Coupled; D013657:Taurodeoxycholic Acid; D000074664:NADPH Oxidase 5; D019255:NADPH Oxidases; C431571:NOX5 protein, human; D043802:GTP-Binding Protein alpha Subunits, Gq-G11