Colorectal carcinogenesis is a multi-step process including both the activation of oncogenes and the loss of tumor suppressor genes. Most of the neoplastic lesions in the colon arise through the progression from normal to hyperproliferative epithelium, adenoma and carcinoma, It is hypothesized that cellular hyperproliferation resulting from either spontaneous mutation or increased in intestinal proliferation leads to clonal expansion and carcinogenesis. Although multiple genetic mutations have been described, the molecular events governing intestinal hyperproliferation is unknown. Recently, an eukaryotic zinc finger protein, gut-enriched Kruppel-like factor (GKLF/KLF4), has been identified to be an important factor in controlling growth arrest. Our laboratory has shown that GKLF gene expression is reduced in colon cancer tissue and that constitutive expression of an antisense GKLF DNA in a colon tumor cell line results in cell hyperproliferation. These data suggest that down-regulation of GKLF may lead to uninhibited cell growth. Furthermore, GKLF mRNA levels increased as colonic epithelium acquired more differentiated phenotype. We hypothesize that up-regulation of GKLF is essential for colonic epithelium to become differentiated and that down-regulation of GKLF will render colonic cells to become hyperproliferated and ultimately neoplastic transformation. The precise physiological function of GKLF in the colon is not clear and its up- and down-stream targets are currently unknown.
The aims of the current study are: (1) to elucidate the physiological properties of GKLF by examining the effect of constitutive overexpression of sense, antisense or dominant-negative mutant GKLF DNA on cell growth and differentiation in normal colon epithelial; adenoma; and cancer cell lines; (2) to investigate the role of GKLF in cell cycle progression by examining its effect on cyclins, cyclin-dependent kinases (cdks) expression, and on transcriptional regulation of the cyclin D1 gene; and (3) to examine molecular mechanisms governing basal transcription of the GKLF gene as well as vit D3- or interferon-gama-promoted GKLF expression. Collectively, the information gained from this proposal will add to our understanding the contribution of GKLF to growth, differentiation, and malignant transformation of the colonic epithelial cells. Ultimately, if the GKLF down-regulation process can be manipulated, it may be possible to use inhibitors of this process for chemoprevention of cancer formation in the gastrointestinal tract.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA082593-04
Application #
6757987
Study Section
Metabolic Pathology Study Section (MEP)
Program Officer
Yassin, Rihab R,
Project Start
2001-07-01
Project End
2006-06-30
Budget Start
2004-07-01
Budget End
2005-06-30
Support Year
4
Fiscal Year
2004
Total Cost
$253,575
Indirect Cost
Name
Boston Medical Center
Department
Type
DUNS #
005492160
City
Boston
State
MA
Country
United States
Zip Code
02118
Chen, Zhi Yi; Wang, Xuesheng; Zhou, Yunhong et al. (2005) Destabilization of Kruppel-like factor 4 protein in response to serum stimulation involves the ubiquitin-proteasome pathway. Cancer Res 65:10394-400
Chen, Zhi Yi; Rex, Sybille; Tseng, Chi-Chuan (2004) Kruppel-like factor 4 is transactivated by butyrate in colon cancer cells. J Nutr 134:792-8
Chen, Zhi Y; Shie, Jue Lon; Tseng, Chi Chuan (2002) STAT1 is required for IFN-gamma-mediated gut-enriched Kruppel-like factor expression. Exp Cell Res 281:19-27
Chen, Zhi Y; Shie, Jue-Lon; Tseng, Chi-Chuan (2002) Gut-enriched Kruppel-like factor represses ornithine decarboxylase gene expression and functions as checkpoint regulator in colonic cancer cells. J Biol Chem 277:46831-9
Stone, Christian D; Chen, Zhi Y; Tseng, Chi Chuan (2002) Gut-enriched Kruppel-like factor regulates colonic cell growth through APC/beta-catenin pathway. FEBS Lett 530:147-52