sodium-taurodeoxycholate and Bile-Reflux

Bile reflux gastritis (BRG) is associated with the development of gastric cancer (GC), but the specific mechanism remains elusive. Here, a comprehensive study is conducted to explore the roles of refluxed bile acids (BAs) and microbiome in gastric carcinogenesis. The results show that conjugated BAs, interleukin 6 (IL-6), lipopolysaccharide (LPS), and the relative abundance of LPS-producing bacteria are increased significantly in the gastric juice of both BRG and GC patients. A secondary BA, taurodeoxycholic acid (TDCA), is significantly and positively correlated with the LPS-producing bacteria in the gastric juice of these patients. TDCA promotes the proliferation of normal gastric epithelial cells (GES-1) through activation of the IL-6/JAK1/STAT3 pathway. These results are further verified in two mouse models, one by gavage of TDCA, LPS, and LPS-producing bacteria (Prevotella melaninogenica), respectively, and the other by bile reflux (BR) surgery, mimicking clinical bile refluxing. Moreover, the bile reflux induced gastric precancerous lesions observed in the post BR surgery mice can be prevented by treatment with cryptotanshinone, a plant-derived STAT3 inhibitor. These results reveal an important underlying mechanism by which bile reflux promotes gastric carcinogenesis and provide an alternative strategy for the prevention of GC associated with BRG.

Topics: Animals; Bile Reflux; Carcinogenesis; Gastritis; Gastrointestinal Microbiome; Humans; Interleukin-6; Lipopolysaccharides; Mice; Stomach Neoplasms; Taurodeoxycholic Acid

Gastroesophageal reflux disease complicated by Barrett's esophagus (BE) is a major risk factor for esophageal adenocarcinoma (EA). However, the mechanisms of the progression from BE to EA are not fully understood. Besides acid reflux, bile acid reflux may also play an important role in the progression from BE to EA. In this study, we examined the role of phosphatidylinositol-specific phospholipase C (PI-PLC) and a novel NADPH oxidase NOX5-S in bile acid-induced increase in cell proliferation. We found that taurodeoxycholic acid (TDCA) significantly increased NOX5-S expression, hydrogen peroxide (H(2)O(2)) production, and cell proliferation in EA cells. The TDCA-induced increase in cell proliferation was significantly reduced by U73122, an inhibitor of PI-PLC. PI-PLCbeta1, PI-PLCbeta3, PI-PLCbeta4, PI-PLCgamma1, and PI-PLCgamma2, but not PI-PLCbeta2 and PI-PLCdelta1, were detectable in FLO cells by Western blot analysis. Knockdown of PI-PLCgamma2 or extracellular signal-regulated kinase (ERK) 2 mitogen-activated protein (MAP) kinase with small interfering RNAs (siRNA) significantly decreased TDCA-induced NOX5-S expression, H(2)O(2) production, and cell proliferation. In contrast, knockdown of PI-PLCbeta1, PI-PLCbeta3, PI-PLCbeta4, PI-PLCgamma1, or ERK1 MAP kinase had no significant effect. TDCA significantly increased ERK2 phosphorylation, an increase that was reduced by U73122 or PI-PLCgamma2 siRNA. We conclude that TDCA-induced increase in NOX5-S expression and cell proliferation may depend on sequential activation of PI-PLCgamma2 and ERK2 MAP kinase in EA cells. It is possible that bile acid reflux present in patients with BE may increase reactive oxygen species production and cell proliferation via activation of PI-PLCgamma2, ERK2 MAP kinase, and NADPH oxidase NOX5-S, thereby contributing to the development of EA.

Topics: Adenocarcinoma; Bile Acids and Salts; Bile Reflux; Blotting, Western; Cell Line, Tumor; Cell Proliferation; Cholagogues and Choleretics; Enzyme Activation; Esophageal Neoplasms; Estrenes; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Neoplastic; Humans; Hydrogen Peroxide; Isoenzymes; Membrane Proteins; Mitogen-Activated Protein Kinase 1; NADPH Oxidase 5; NADPH Oxidases; Phosphodiesterase Inhibitors; Phospholipase C gamma; Pyrrolidinones; Reverse Transcriptase Polymerase Chain Reaction; RNA Interference; Taurodeoxycholic Acid

MUC4 (mucin 4) is a membrane-bound mucin overexpressed in the early steps of oesophageal carcinogenesis and implicated in tumour progression. We previously showed that bile acids, main components of gastro-oesophageal reflux and tumour promoters, up-regulate MUC4 expression [Mariette, Perrais, Leteurtre, Jonckheere, Hemon, Pigny, Batra, Aubert, Triboulet and Van Seuningen (2004) Biochem. J. 377, 701-708]. HNF (hepatocyte nuclear factor) 1alpha and HNF4alpha transcription factors are known to mediate bile acid effects, and we previously identified cis-elements for these factors in MUC4 distal promoter. Our aim was to demonstrate that these two transcription factors were directly involved in MUC4 activation by bile acids. MUC4, HNF1alpha and HNF4alpha expressions were evaluated by immunohistochemistry in human oesophageal tissues. Our results indicate that MUC4, HNF1alpha and HNF4alpha were co-expressed in oesophageal metaplastic and adenocarcinomatous tissues. Studies at the mRNA, promoter and protein levels indicated that HNF1alpha regulates endogenous MUC4 expression by binding to two cognate cis-elements respectively located at -3332/-3327 and -3040/-3028 in the distal promoter. We also showed by siRNA (small interfering RNA) approach, co-transfection and site-directed mutagenesis that HNF1alpha mediates taurodeoxycholic and taurochenodeoxycholic bile acid activation of endogenous MUC4 expression and transcription in a dose-dependent manner. In conclusion, these results describe a new mechanism of regulation of MUC4 expression by bile acids, in which HNF1alpha is a key mediator. These results bring new insights into MUC4 up-regulation in oesophageal carcinoma associated with bile reflux.

Topics: Bile Reflux; Cell Line, Tumor; Esophageal Neoplasms; Gene Expression Regulation, Neoplastic; Hepatocyte Nuclear Factor 1-alpha; Hepatocyte Nuclear Factor 4; Humans; Immunohistochemistry; Mucin-4; Mucins; Promoter Regions, Genetic; RNA, Small Interfering; Taurochenodeoxycholic Acid; Taurodeoxycholic Acid; Transcription, Genetic; Transfection; Up-Regulation

Since chronic gastritis is adversely affected by reflux bile acids, we are interested in which of these bile acids cause the most damage to the gastric mucosa as ulcerogenic factors in the stomach. We examined 34 patients suffering from the peptic ulcers, and have assumed that taurine conjugated deoxycholic acid (TDC) and chenodeoxycholic acid (TCDC) may act as the mst ulcerogenic factors. Moreover TCDC was suggested to be associated with the cystic dilatation of the gastric gland. It was also suggested that TDC is involved in the increased frequency of intestinal metaplasia as a factor backgrounding cancer.

Topics: Adult; Aged; Atrophy; Bile Reflux; Chenodeoxycholic Acid; Dilatation, Pathologic; Gastric Mucosa; Humans; Middle Aged; Stomach Ulcer; Taurodeoxycholic Acid

Bile acid processing in the long-term, bile duct obstructed rat liver was studied ex vivo. Twenty four and 72 h, respectively, after bile duct obstruction the isolated liver was perfused with taurodeoxycholate (16 nmol/min per g liver) the bile duct still being closed. Uptake, metabolism and regurgitation profile were traced by bolus injection of tritium-labeled bile acid; in addition, concurrent histological changes were examined by light- and electron microscopy. Ligation caused dilatation of the intrahepatic ductular branches and increased the serum bile acid concentration to 740 +/- 75 microM (controls: 16 +/- 2.12), reaching its maximum within 24 h. At 16 nmol/min per g liver uptake rate was > 96% in controls and in bile duct obstructed rats. Maximal uptake rates (assessed separately) differed between controls and bile duct obstructed rats (700 nmol/min per g liver vs. 460). Controls excreted more than 80% of labeled bile acid in bile within 10 min after bolus injection. Biliary recovery of label was virtually completed after 30 min. In bile duct obstructed rats excretion of label back to the perfusate effluent (regurgitation) started quantitatively 5 min after bolus application and peaked between 10 and 40 min; after 80 min, effluent recovery was incomplete (about 60% of bolus injected). Biliary bile acids of controls consisted of about 20% taurodeoxycholate-metabolites; bile acids in the perfusate effluent of bile duct obstructed rats of about 55%. The major metabolite in all animal groups was taurocholate; minor metabolites were tauroursocholate, tauro-3 alpha,7 = 0,12 alpha-cholanoic acid and 3-sulfo-taurodeoxycholate. Histologically, inflammation and periportal edema were present after 1 day of bile duct obstruction. After 3 days, marked proliferation of bile ductules was the dominant histological feature. It is concluded that during initial bile duct obstruction, bile acid processing is not altered, although ultrastructural alterations occur early.

Topics: Animals; Bile; Bile Acids and Salts; Bile Reflux; Cholestasis, Intrahepatic; In Vitro Techniques; Liver; Male; Perfusion; Rats; Rats, Sprague-Dawley; Taurodeoxycholic Acid