Inhibition of nucleostemin upregulates CDX2 expression in HT29 cells in response to bile acid exposure: implications in the pathogenesis of Barrett's esophagus.
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 microM 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.


CONCLUSIONS
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.
Sun
Yong-Gang
YG
Department of Gastroenterology, Southwest Hospital, Third Military Medical University, Chongqing, 400038, China.
Wang
Xing-Wei
XW
Yang
Shi-Ming
SM
Zhou
Gang
G
Wang
Wei-Qiang
WQ
Wang
Hong-Bin
HB
Wang
Rong-Quan
RQ
Fang
Dian-Chun
DC
D001471:Barrett Esophagus / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D001706:Biopsy; D015153:Blotting, Western; D000071616:CDX2 Transcription Factor; D002352:Carrier Proteins / Q000037:antagonists & inhibitors*; D002400:Cathartics / Q000494:pharmacology; D002635:Chenodeoxycholic Acid / Q000494:pharmacology*; D004947:Esophagus / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D019204:GTP-Binding Proteins; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D019073:HT29 Cells; D018398:Homeodomain Proteins / Q000096:biosynthesis / Q000235:genetics*; D006801:Humans; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors*; D020411:Oligonucleotide Array Sequence Analysis; D012334:RNA, Neoplasm / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000071616:CDX2 Transcription Factor; C491270:CDX2 protein, human; D002352:Carrier Proteins; D002400:Cathartics; C469949:GNL3 protein, human; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; D012334:RNA, Neoplasm; D002635:Chenodeoxycholic Acid; D019204:GTP-Binding Proteins