Inhibition of Nucleostemin Upregulates CDX2 Expression in HT29 Cells in Response to Bile Acid Exposure: Implications in
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ORIGINAL ARTICLE
Inhibition of Nucleostemin Upregulates CDX2 Expression in HT29 Cells in Response to Bile Acid Exposure: Implications in the Pathogenesis of Barrett’s Esophagus Yong-Gang Sun & Xing-Wei Wang & Shi-Ming Yang & Gang Zhou & Wei-Qiang Wang & Hong-Bin Wang & Rong-Quan Wang & Dian-Chun Fang
Received: 10 February 2009 / Accepted: 15 April 2009 / Published online: 16 May 2009 # 2009 The Society for Surgery of the Alimentary Tract
Abstract Background Barrett’s esophagus (BE), a squamous-to-columnar metaplasia, may originate from growth-promoting mutations in metaplastic stem cells. Nucleostemin is a protein highly expressed in undifferentiated embryonic stem cells. The objectives of this study were to explore the potential role of nucleostemin in the pathogenesis of BE Methods The expression profiles of 30,968 genes were compared between BE and normal esophageal tissues (n=6 in each group) by using oligo microarray. Three siRNA plasmid expression vectors against nucleostemin, pRNAi-1, pRNAi-2, and pRNAi-3, were constructed and transfected into HT29 cells. In addition, HT29 cells were exposed to 100–1,000 μM chenodeoxycholic acid (CDC), a bile acid, for 2, 12, and 24 h, and then messenger RNA and protein expressions of nucleostemin and CDX2 were determined by reverse-transcriptase polymerase chain reaction and Western blotting. Results Four hundred and twenty-six differentially expressed genes were detected in BE; 142 were upregulated and 284 downregulated. Nucleostemin was downregulated while CDX2 was upregulated. In vitro, all the recombinant plasmids inhibited the nucleostemin expression in transfected HT29 cells, with pRNAi-1 being the most effective. CDX2 expression was significantly increased in pRNAi-1-transfected HT29 cells, compared with that in the empty plasmid (pRNAT-U6.1/Neo) transfected or untransfected HT29 cells. In addition, CDX2 expression was increased whereas nucleostemin expression was decreased in a dose- and time-dependent manner in HT29 cells treated with CDC. Conclusion These findings suggest that the inhibition of nucleostemin expression in “esophageal stem cells” in response to bile acid exposure may be involved in the pathogenesis of BE through upregulating CDX2 expression. Keywords Barrett’s esophagus . Nucleostemin . CDX2 . HT29 cell . Oligomicroarray
Introduction The incidence of esophageal adenocarcinoma has increased at a rate that is among the highest of all cancers.1,2 The major risk factor for esophageal adenocarcinoma is the presence of Barrett’s esophagus (BE), a premalignant neoplastic lesion Y.-G. Sun : X.-W. Wang : S.-M. Yang : G. Zhou : W.-Q. Wang : H.-B. Wang : R.-Q. Wang : D.-C. Fang (*) Department of Gastroenterology, Southwest Hospital, Third Military Medical University, Chongqing 400038, China e-mail: [email protected]
that is characterized by intestinal metaplasia replacing the normal squamous esophageal epithelia.3 The presence of BE increases the overall risk of adenocarcinoma by 40-fold.4 Nucleostemin, a newly found p53-binding protein, exists mainl
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