Gastrointestinal cancer is a significant health problem, ranking fourth in incidence and second in death in the United States. Abnormal differentiation and increased proliferation are hallmarks of carcinogenesis. The molecular mechanisms that regulate cellular proliferation and differentiation in gastrointestinal development are far from being understood completely. Here we focus on the homeobox-transcription factors Cdx1 and Cdx2, which are primer candidates as central regulators of both intestinal development and GI carcinogenesis. While several hundred articles have appeared that suggest these genes as master regulators of early gut development and GI cancers, the definitive experiment, that is the analysis intestinal epithelia deficient for Cdx1, Cdx2 or both has not yet been performed. Therefore, we will develop and exploit new genetic tools to elucidate fundamental questions regarding the function of these two genes. In addition, in an innovative approach we will use the 1.8 million monoclonal crypts of the mouse intestine as a high- throughput """"""""laboratory"""""""" to identify novel proto-oncogenes, tumor suppressors, and cancer modifiers by transposon-mediated insertional mutagenesis.
Specific Aims :
In Aim 1, we will determine the function of Cdx genes in anterior-posterior patterning of gut endoderm. We will test our hypothesis that Cdx1 and Cdx2 are critical mediators of anterior-posterior patterning of the primitive gut by analyzing the development of early gut endoderm deficient for Cdx1, Cdx2 or Cdx2/Cdx1, which we will obtain by conditional gene ablation in mice.
In Aim 2, we will analyze the function of Cdx genes in intestinal differentiation and tumorigenesis. We hypothesize that Cdx1 and Cdx2 are critical regulators of intestinal differentiation, and that Cdx2 acts as a tumor suppressor in the intestinal epithelium. We will evaluate our hypotheses by deriving mice deficient for Cdx1, Cdx2 (or Cdx2/Cdx1) after cytodifferentiation has occurred. Mice will be analyzed for the elaboration of the mature intestinal cell types, for their rate of proliferation, and their propensity for tumorigenesis in multiple models.
In Aim 3, we will employ a novel genetic screen to uncover novel proto-oncogenes and tumor suppressors in colorectal cancer. We will utilize the innovative and powerful approach of retrotransposon-driven random insertional mutagenesis to mutagenize the 1.8 million crypts of the mouse intestine. The resulting polyps will be characterized histologically, and the tumor-causing mutation sequenced. Novel proto-oncogenes and tumor suppressor genes will be screen for mutations in human colorectal cancer. Together, this proposal will further our understanding of GI development and cancer, and allow for the development of novel diagnostic and possibly therapeutic tools in the future.
|Kieckhaefer, Julia; Lukovac, Sabina; Ye, Diana Z et al. (2016) The RNA polymerase III subunit Polr3b is required for the maintenance of small intestinal crypts in mice. Cell Mol Gastroenterol Hepatol 2:783-795|
|Sheaffer, Karyn L; Elliott, Ellen N; Kaestner, Klaus H (2016) DNA Hypomethylation Contributes to Genomic Instability and Intestinal Cancer Initiation. Cancer Prev Res (Phila) 9:534-46|
|Shin, Soona; Upadhyay, Naman; Greenbaum, Linda E et al. (2015) Ablation of Foxl1-Cre-labeled hepatic progenitor cells and their descendants impairs recovery of mice from liver injury. Gastroenterology 148:192-202.e3|
|Elliott, Ellen N; Kaestner, Klaus H (2015) Epigenetic regulation of the intestinal epithelium. Cell Mol Life Sci 72:4139-56|
|Jiao, Yang; Ye, Diana Z; Li, Zhaoyu et al. (2015) Protein tyrosine phosphatase of liver regeneration-1 is required for normal timing of cell cycle progression during liver regeneration. Am J Physiol Gastrointest Liver Physiol 308:G85-91|
|Sheaffer, Karyn L; Kaestner, Klaus H (2012) Transcriptional networks in liver and intestinal development. Cold Spring Harb Perspect Biol 4:a008284|
|Gao, Yan; Schug, Jonathan; McKenna, Lindsay B et al. (2011) Tissue-specific regulation of mouse microRNA genes in endoderm-derived tissues. Nucleic Acids Res 39:454-63|
|Gao, Nan; Davuluri, Gangarao; Gong, Weilong et al. (2011) The nuclear pore complex protein Elys is required for genome stability in mouse intestinal epithelial progenitor cells. Gastroenterology 140:1547-55.e10|
|Maloum, Faiza; Allaire, Joannie M; Gagne-Sansfacon, Jessica et al. (2011) Epithelial BMP signaling is required for proper specification of epithelial cell lineages and gastric endocrine cells. Am J Physiol Gastrointest Liver Physiol 300:G1065-79|
|May, Catherine Lee; Kaestner, Klaus H (2010) Gut endocrine cell development. Mol Cell Endocrinol 323:70-5|
Showing the most recent 10 out of 33 publications