Caudal homeobox protein Cdx-2 cooperates with Wnt pathway to regulate claudin-1 expression in colon cancer cells

Ajaz Ahmad Bhat, Ashok Sharma, Jillian Pope, Moorthy Krishnan, Mary K. Washington, Amar B. Singh, Punita Dhawan

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

Dysregulation of tight junctions (TJs) is often associated with human diseases including carcinogenesis and recent studies support role of TJ integral proteins in the regulation of Epithelial-to-Mesenchymal Transition (EMT). In this regard, expression of claudin-1, a key constituent of TJs, is highly increased in colon cancer and is causally associated with the tumor growth and progression. However, mechanism/s underlying regulation of claudin-1 expression in intestinal epithelial cells remains poorly understood. In our studies, we have identified putative binding sites for intestinal transcription factors Cdx1, -2 and GATA4 in the 5′-flanking region of the claudin-1 gene. Our further studies using full length and/or deletion mutant constructs in two different human colon cancer cell lines, SW480 and HCT116, showed key role of Cdx1, Cdx2 and GATA4 in the regulation of claudin-1 mRNA expression. However, overexpression of Cdx2 had the most potent effect upon claudin-1 mRNA expression and promoter activity. Also, in colon cancer patient samples, we observed a significant and parallel correlation between claudin-1 and Cdx2 expressions. Chromatin immunoprecipitation (ChIP) assay confirmed the Cdx2 binding with claudin-1 promoter in vivo. Using Cdx2 deletion mutant constructs, we further mapped the Cdx2 C-terminus domain to be important in the regulation of claudin-1 promoter activity. Interestingly, co-expression of activated β-catenin further induced the Cdx2-dependent upregulation of claudin-1 promoter activity while expression of the dominant negative (dn)-TCF-4 abrogated this activation. Taken together, we conclude that homeodomain transcription factors Cdx1, Cdx2 and GATA4 regulate claudin-1 gene expression in human colon cancer cells. Moreover, a functional crosstalk between Wnt-signaling and transcriptional activation related to caudal-related homeobox (Cdx) proteins and GATA-proteins is demonstrated in the regulation of claudin-1 promoter-activation.

Original languageEnglish
Article numbere37174
JournalPLoS One
Volume7
Issue number6
DOIs
Publication statusPublished - 15 Jun 2012
Externally publishedYes

Fingerprint

Claudin-1
homeodomain proteins
Homeodomain Proteins
Wnt Signaling Pathway
colorectal neoplasms
Colonic Neoplasms
Cells
promoter regions
tight junctions
transcription factors
mutants
transcriptional activation
Tight Junctions
Chemical activation
human diseases
carcinogenesis
chromatin
binding sites
epithelial cells
proteins

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Medicine(all)

Cite this

Caudal homeobox protein Cdx-2 cooperates with Wnt pathway to regulate claudin-1 expression in colon cancer cells. / Bhat, Ajaz Ahmad; Sharma, Ashok; Pope, Jillian; Krishnan, Moorthy; Washington, Mary K.; Singh, Amar B.; Dhawan, Punita.

In: PLoS One, Vol. 7, No. 6, e37174, 15.06.2012.

Research output: Contribution to journalArticle

Bhat, Ajaz Ahmad ; Sharma, Ashok ; Pope, Jillian ; Krishnan, Moorthy ; Washington, Mary K. ; Singh, Amar B. ; Dhawan, Punita. / Caudal homeobox protein Cdx-2 cooperates with Wnt pathway to regulate claudin-1 expression in colon cancer cells. In: PLoS One. 2012 ; Vol. 7, No. 6.
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