Inactivation of Itf2 promotes intestinal tumorigenesis in ApcMin/+ mice
Introduction
Colorectal cancer is a genetic disease that develops from adenomatous precursor lesions by the accumulation of multiple independent somatic alterations in oncogenes and tumor suppressor genes [1]. Inactivating mutations of the APC tumor suppressor gene are viewed as an early event in up to 80% of human sporadic colorectal cancers and have been implicated in the development of hundreds of adenomas mainly in the colon in hereditary familial adenomatous polyposis (FAP) [2], [3], [4]. Loss of APC function leads to deregulation of the Wnt/β-catenin signaling cascade, resulting in stabilization and nuclear translocation of the protein β-catenin (reviewed in Ref. [1]). Subsequently, β-catenin modulates the transcription of its target genes. The gene ITF2 alias TCF4 encoding the basic helix-loop-helix protein (bHLH) and transcription factor ITF-2B has been identified as a β-catenin target gene [5]. Previously, we have demonstrated that deregulated activity of the protein β-catenin induces the transcription of the ITF2 gene in colonic adenomas. However, during tumor progression, ITF-2B protein levels are frequently reduced due to loss of heterozygosity on chromosome 18q as well as deacetylation of the ITF2 promoter, suggesting that loss of ITF2 function is necessary for tumor development [6].
The ApcMin/+ mouse is a widely used mouse model for the study of colorectal carcinogenesis. ApcMin/+ mice carry an inactivating mutation in one allele of the Apc tumor suppressor gene [7]. Somatic loss of the remaining Apc wild-type allele leads to deregulation of the Wnt signaling pathway, resulting in the development of a multitude of tumors throughout the whole intestinal tract [8]. The majority of these neoplastic lesions is distributed to the small intestine and only few occur in the colon [9], [10], [11]. In ApcMin/+ mice all intestinal tumors are benign adenomas. Progression to adenocarcinoma is very rare and may occasionally be observed in older animals. ApcMin/+ mice die as a consequence of secondary effects of tumor growth, mainly intestinal bleeding and obstruction caused by tumors [9], [11].
The aim of the present study was to investigate the role of Itf2 in intestinal tumorigenesis in vivo. Therefore, we inactivated Itf2 specifically in the intestinal epithelium of ApcMin/+ mice and analyzed consequences for tumor formation.
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Animals
Itf2fl/fl mice [12] were crossed with vil-Cre+ mice [13]. Itf2fl/fl;vil-Cre+ mice heterozygous for the vil-Cre transgene were bred into the ApcMin/+ background to obtain Itf2fl/fl;ApcMin/+ and Itf2fl/fl;vil-Cre+;ApcMin/+ mice, respectively. In all experiments, mice on the Itf2fl/fl background were used as controls. ApcMin/+ mice were purchased from the Jackson Laboratory. All mouse strains were maintained on a C57BL/6 background.
Mice were inspected on a daily basis and sacrificed when moribund.
Results
To study the effect of inactivation of the Itf2 gene on intestinal tumor formation, we crossed Itf2fl/fl mice with mice expressing Cre recombinase under the control of the intestinal epithelium specific Villin promoter ([7], [12], [13], [16]). Itf2fl/fl;vil-Cre+ (Itf2−/−) mice were viable, fertile and showed no increased morbidity and mortality. Detailed histological and immunohistochemical analysis of small intestine and colon revealed no changes in gut anatomy or in the number and
Discussion
ITF-2B is a widely expressed transcription factor that is involved in differentiation processes [17]. ITF2 expression is up-regulated in primary endometroid ovarian carcinomas due to deregulation of the Wnt/β-catenin signaling cascade and ITF-2B promotes neoplastic transformation of RK3E cells, an adenovirus E1A-immortalized epithelial cell line [5] In the past constitutive and inducible knockout mouse models revealed a crucial role for Itf2 in both B and T lymphocyte development [12], [18] and
Conflict of interest
None.
Acknowledgments
The authors gratefully acknowledge Ingrid Renner-Müller and Petra Renner for help with animal care and Felix Hiltwein for help with necropsy. This work was supported by a grant of the German Research Foundation (KO1826/6-1) to FTK.
References (26)
Molecular genetics of colorectal cancer
Annu. Rev. Pathol
(2011)A genetic model for colorectal tumorigenesis
Cell
(1990)Identification of a gene located at chromosome 5q21 that is mutated in colorectal cancers
Science
(1991)APC mutations occur early during colorectal tumorigenesis
Nature
(1992)ITF-2, a downstream target of the Wnt/TCF pathway, is activated in human cancers with beta-catenin defects and promotes neoplastic transformation
Cancer Cell
(2002)- et al.
ITF-2 is disrupted via allelic loss of chromosome 18q21, and ITF-2B expression is lost at the adenoma-carcinoma transition
Gastroenterology
(2009) Multiple intestinal neoplasia caused by a mutation in the murine homolog of the APC gene
Science
(1992)Loss of Apc heterozygosity and abnormal tissue building in nascent intestinal polyps in mice carrying a truncated Apc gene
Proc. Natl. Acad. Sci. U. S. A
(1995)A dominant mutation that predisposes to multiple intestinal neoplasia in the mouse
Science
(1990)Studies of neoplasia in the min mouse
Biochim. Biophys. Acta
(1997)
Pathology of Mouse Models of Intestinal cancer: Consensus Report and Recommendations
The basic helix-loop-helix transcription factor E2-2 is involved in T lymphocyte development
Eur. J. Immunol.
Tissue-specific and inducible Cre-mediated recombination in the gut epithelium
Genesis
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These authors contributed equally to this work.