| Barrett esophagus (BE) is characterized by the metaplastic replacement of squamous epithelial cells by intestinal epithelium–containing goblet cells.BE exhibits high affinity for esophageal adenocarcinoma(EAC).The patients with BE raise 30 times risk than everyman to develop EAC. The progression from Barrett's metaplasia to adenocarcinoma will experience metaplasia,anaplasia and carcinomatous change.Bile acids are normal constituents of the gastro-intestinal tract where they play an important role in gastroesophageal reflux diseases,such as reflux esophagitis,BE and its complicated EAC. Deoxycholic acid (DCA) as the important component of bile is associated with BE and EAC. But the exact mechanism of their tumor promoting activity is uncertain.p38 mitogen-activated protein kinase(p38MAPKs) is one kind of serine- threonine protein kinase.As one of the signal pathways between cells,it is activated by various kinds of stimulus to participate the cell apoptosis, differe- ntiation,inflammation,stress and so on.It had been found that the expression of p-p38 had increased during the growth and differentiation of intestinal epithelium cells,and it had been specificly distributed in the caryon of intestinal chorioepithelium.Recent studies of using small intestinal markers acid mucins and sucrase-isomaltase to detect postoperative recurrence of EAC showed that the esophageal epithelium of metaplasia had been similar with the small intestinal epithelium. CDX2 played an important role in the development of the intestine.But there was no expression of CDX2 in the normal mucous membrane epithelium of esophagus and stomach. Since the squamous epithelial cells was replaced by intestinal epithelium,the expression of CDX2 would increased obviously. Recently,the domestic scholar confirmed that up-regulated expression of CDX2 is associated with p38 activated in the lesion of mucous membrane of stomach.We hypothesized that p38 had the same function in the metaplasia of esophageal epithelium.Objective:To investigate the relationship between p38 and mechanism of metaplasia of esophageal epithelium,using DCA treated human normal esophageal cells.Methods:Normal esophageal epithelium was proved by HE staining. Immunocytochemistry was used to identify the character of epithelial cell (Monoclonal Antibody Cytokeratin14).Western blot analysis was applied to measure the dynamic expression of p-p38 and CDX2 of esophageal epithelial cells treated with different concentrations of DCA.Result:1 DCA can promote p38 activation of esophageal epithelial cells Western blot showed that t-p38 expression had no changed, with (73.2±1.3) in control group, and (76.8±1.5),(77.8±1.9),(75.5±2.3),(72.6±1.0) in experimental groups at different concentrations of DCA (100μmol/L,250μmol/L,500μmol/L,1000μmol/L) after 24h.With the raising of concentrations of DCA , the relative expression of p-p38 in control group was (13.7±1.0)%, with (17.1±1.4)%,(29.7±2.1)%,(44.0±1.7)% and (26.0±1.5)% in experimental groups at different concentrations of DCA (100μmol/L,250μmol/L,500μmol/L,1000μmol/L) after 24h. Phosphorylation of p38 was highest at 500μmol/L DCA. The relative expression of p-p38 in experimental groups increased significantly compared with the control group,p<0.05,p<0.01,p<0.01 respectively.Compared among different concentrations of DCA,all of them had significant changes p<0.05.2 DCA can up-regulate CDX2 expression of esophageal epithelial cells Western blot showed that there was no expression of CDX2 in control group.While with the raising of concentrations of DCA , the relative expression of CDX2 in experimental groups gradually increased, respectively (0.42±0.03),(5.63±0.52),(8.59±1.25) and (6.19±1.16) at different concentra -tions of DCA (100μmol/L,250μmol/L,500μmol/L,1000μmol/L) after 24h.Also the expression of CDX2 was highest at 500μmol/L DCA.Compared with the control group and 100μmol/L DCA group ,other groups had increased significantly, all of them presented p<0.01. 100μmol/L DCA group had no significant difference compared with control group p>0.05.3 Inhibited the p38MAPKs pathways,observation of the p38 and CDX2 protein expressionUsing the specific inhibitor of p38 SB203580 (20umol/L) pretreated the esophageal epithelial cells for 2h,then the cells were washed with PBS and cultured in D-KSFM containing 500μmol/L DCA for 24h.Compared with the effect of 500μmol/L DCA exposure alone, phosphorylation of p38 decreased obviously, (28.3±2.2)% vs (50.5±9.5)%, p<0.01,but remained up the control group. (28.3±2.2)% vs (13.8±0.9)%, p<0.05. SB203580 alone had a nonsignificant.So did the expression of CDX2. Compared with the effect of 500μmol/L DCA exposure alone, the expression of CDX2 decreased obviously in the SB203580+DCA group, (0.94±0.13) vs (2.31±0.41),p<0.01. SB203580 alone had a nonsignificant.Conclusion:1 DCA could promote the phosphorylation of p38 in a dose-dependant manner in human normal esophageal epithelial cells.2 DCA could induce the expression of CDX2 in human normal esop -hageal epithelial cells in a dose-dependant manner ,and presented positive correlation with p-p38 in certain degree.The result indicated that phosphorylation of p38 played an important role in the mechanism of metaplasia of esophageal epithelium.3 Using the specific inhibitor of p38MAPKs SB203580 could obviously decreased the expression of p-p38 and CDX2,which will as a new meaning to prevent BE.
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