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Balbinot C, Vanier M, Armant O, Nair A, Penichon J, Soret C, Martin E, Saandi T, Reimund JM, Deschamps J, Beck F, Domon-Dell C, Gross I, Duluc I, Freund JN. Fine-tuning and autoregulation of the intestinal determinant and tumor suppressor homeobox gene CDX2 by alternative splicing. Cell Death Differ 2017; 24:2173-2186. [PMID: 28862703 DOI: 10.1038/cdd.2017.140] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 07/23/2017] [Accepted: 07/25/2017] [Indexed: 12/20/2022] Open
Abstract
On the basis of phylogenetic analyses, we uncovered a variant of the CDX2 homeobox gene, a major regulator of the development and homeostasis of the gut epithelium, also involved in cancer. This variant, miniCDX2, is generated by alternative splicing coupled to alternative translation initiation, and contains the DNA-binding homeodomain but is devoid of transactivation domain. It is predominantly expressed in crypt cells, whereas the CDX2 protein is present in crypt cells but also in differentiated villous cells. Functional studies revealed a dominant-negative effect exerted by miniCDX2 on the transcriptional activity of CDX2, and conversely similar effects regarding several transcription-independent functions of CDX2. In addition, a regulatory role played by the CDX2 and miniCDX2 homeoproteins on their pre-mRNA splicing is displayed, through interactions with splicing factors. Overexpression of miniCDX2 in the duodenal Brunner glands leads to the expansion of the territory of these glands and ultimately to brunneroma. As a whole, this study characterized a new and original variant of the CDX2 homeobox gene. The production of this variant represents not only a novel level of regulation of this gene, but also a novel way to fine-tune its biological activity through the versatile functions exerted by the truncated variant compared to the full-length homeoprotein. This study highlights the relevance of generating protein diversity through alternative splicing in the gut and its diseases.
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Affiliation(s)
- Camille Balbinot
- Université de Strasbourg, Inserm, UMR_S1113, FMTS, Strasbourg 67000, France
| | - Marie Vanier
- Université de Strasbourg, Inserm, UMR_S1113, FMTS, Strasbourg 67000, France
| | - Olivier Armant
- Karlsruhe Institute of Technology, Institute of Toxicology and Genetics, Postfach 3640, Karlsruhe 76021, Germany
| | - Asmaa Nair
- Université de Strasbourg, Inserm, UMR_S1113, FMTS, Strasbourg 67000, France
| | - Julien Penichon
- Université de Strasbourg, Inserm, UMR_S1113, FMTS, Strasbourg 67000, France
| | - Christine Soret
- Université de Strasbourg, Inserm, UMR_S1113, FMTS, Strasbourg 67000, France
| | - Elisabeth Martin
- Université de Strasbourg, Inserm, UMR_S1113, FMTS, Strasbourg 67000, France
| | - Thoueiba Saandi
- Université de Strasbourg, Inserm, UMR_S1113, FMTS, Strasbourg 67000, France
| | - Jean-Marie Reimund
- Université de Strasbourg, Inserm, UMR_S1113, FMTS, Strasbourg 67000, France
| | - Jacqueline Deschamps
- Hubrecht Institute, Developmental Biology and Stem Cell Research, Uppsalalaan 8, Utrecht 3584 CT, The Netherlands
| | - Felix Beck
- Barts and The London School of Medicine and Dentistry, London E1 2ES, UK
| | - Claire Domon-Dell
- Université de Strasbourg, Inserm, UMR_S1113, FMTS, Strasbourg 67000, France
| | - Isabelle Gross
- Université de Strasbourg, Inserm, UMR_S1113, FMTS, Strasbourg 67000, France
| | - Isabelle Duluc
- Université de Strasbourg, Inserm, UMR_S1113, FMTS, Strasbourg 67000, France
| | - Jean-Noël Freund
- Université de Strasbourg, Inserm, UMR_S1113, FMTS, Strasbourg 67000, France
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Zheng J, He S, Qi J, Wang X, Yu J, Wu Y, Gao Q, Wang K, Sun X. Targeted CDX2 expression inhibits aggressive phenotypes of colon cancer cells in vitro and in vivo. Int J Oncol 2017. [PMID: 28627695 PMCID: PMC5505129 DOI: 10.3892/ijo.2017.4040] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Loss of caudal type homeobox 2 (CDX2) is associated with the development of human colorectal cancer, while human telomerase reverse transcriptase (hTERT) frequently occurs in variety of human cancers. We investigated the effects of restoration of CDX2 expression using a hypoxia-inducible hTERT promoter-driven vector (pLVX-5HRE-hTERTp-CDX2-3FLAG) on colon cancer cell viability, cell cycle distribution, apoptosis, colony formation, invasion ability and xenograft tumor growth in nude mice. CDX2 overexpression significantly inhibited viability, colony formation, and the invasion and migration ability of LoVo cells, and induced cell cycle arrest and apoptosis in vitro, especially under hypoxic culture conditions. Overexpression of CDX2 under normoxic conditions significantly suppressed the expression of TGF-β, cyclin D1, uPA, MMP-9, MMP-2, and Bcl-2, and stimulated the expression of collagen IV, laminin-1, and Bax. Overexpression of CDX2 reduced colon cancer xenograft tumor formation in nude mice which was associated with downregulation of Ki-67. In conclusion, overexpression of CDX2 using a hypoxia-inducible hTERT promoter-driven vector suppressed malignant progression of colon cancer cells in vitro and in vivo. These results suggest that pLVX-5HRE-hTERTp-CDX2-3FLAG gene therapy may be a promising novel approach to treat colon cancer.
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Affiliation(s)
- Jianbao Zheng
- Department of General Surgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Sai He
- Department of Breast Surgery, Shaanxi Provincial Tumor Hospital, Xi'an, Shaanxi 710061, P.R. China
| | - Jie Qi
- Second Department of Cardiovascular Medicine, Shaanxi Provincial People's Hospital, Xi'an, Shaanxi 710068, P.R. China
| | - Xiaolong Wang
- Department of Tumor Surgery, The Second Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an, Shaanxi 710004, P.R. China
| | - Junhui Yu
- Department of General Surgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Yunhua Wu
- Department of General Surgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Qi Gao
- Department of General Surgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Kai Wang
- Department of General Surgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Xuejun Sun
- Department of General Surgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
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Freund JN, Duluc I, Reimund JM, Gross I, Domon-Dell C. Extending the functions of the homeotic transcription factor Cdx2 in the digestive system through nontranscriptional activities. World J Gastroenterol 2015; 21:1436-1443. [PMID: 25663763 PMCID: PMC4316086 DOI: 10.3748/wjg.v21.i5.1436] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Revised: 11/25/2014] [Accepted: 12/16/2014] [Indexed: 02/06/2023] Open
Abstract
The homeoprotein encoded by the intestinal-specific Cdx2 gene is a major regulator of gut development and homeostasis, also involved in colon cancer as well as in intestinal-type metaplasias when it is abnormally expressed outside the gut. At the molecular level, structure/function studies have demonstrated that the Cdx2 protein is a transcription factor containing a conserved homeotic DNA-binding domain made of three alpha helixes arranged in a helix-turn-helix motif, preceded by a transcriptional domain and followed by a regulatory domain. The protein interacts with several thousand sites on the chromatin and widely regulates intestinal functions in stem/progenitor cells as well as in mature differentiated cells. Yet, this transcription factor also acts trough original nontranscriptional mechanisms. Indeed, the identification of novel protein partners of Cdx2 and also of a splicing variant revealed unexpected functions in the control of signaling pathways like the Wnt and NF-κB pathways, in double-strand break DNA repair and in premessenger RNA splicing. These novel functions of Cdx2 must be considered to fully understand the complexity of the role of Cdx2 in the healthy intestine and in diseases.
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