We have described a genetic polymorphism of NKX3.1, a homeobox gene with organ-specific expression confined to the prostate in the adult. The polymorphism changes codon 154 by substituting a T for a C, thereby resulting in a missense codon 52 that replaces arginine with cysteine (R52C). In a survey of DNA samples we found that NKX3.1 R52C was present in 4 percent of normal donors, but in 12 percent of prostate cancer patients, suggesting that NKX3.1 R52C may confer 3-fold risk for prostate cancer. Moreover, the amino acid alteration coded by the polymorphism increases the avidity of DNA binding by the NKX3.1 protein. Therefore, this polymorphism represents a gain-of-function mutation that appears to affect prostate cancer risk. The proposal focuses on the DNA binding and transcriptional activation by NKX3.1 wild type and polymorphic proteins. We will identify the true DNA binding site for NKX3.1. We will construct reporter plasmids with the NKX3.1 binding site in order to study differences between mutant and polymorphic proteins and to perform deletion analysis of NKX3.1. We will construct chimaeric NKX3.1/GAL4 fusion proteins to study the effects of NKX3.1 sequences flanking the homeodomain on the activity of DNA binding and activation of a known transcription factor. To enhance the in vitro phenotypic impact of the amino acid 52 mutation, we generate other amino acid substitutions and characterize them in reporter gene assays. Lastly, through differential display technology, we will identify genes that are regulated by NKX3.1 to begin to understand the signaling pathways that are activated by NKX3.1 and to study NKX3.1-responsive promoters that are in vivo targets for the protein.

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Research Project (R01)
Project #
5R01ES009888-03
Application #
6382305
Study Section
Special Emphasis Panel (ZES1-JPM-B (01))
Program Officer
Velazquez, Jose M
Project Start
1999-05-01
Project End
2003-04-30
Budget Start
2001-05-01
Budget End
2003-04-30
Support Year
3
Fiscal Year
2001
Total Cost
$208,854
Indirect Cost
Name
Georgetown University
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
049515844
City
Washington
State
DC
Country
United States
Zip Code
20057
Muhlbradt, Erin; Asatiani, Ekaterina; Ortner, Elizabeth et al. (2009) NKX3.1 activates expression of insulin-like growth factor binding protein-3 to mediate insulin-like growth factor-I signaling and cell proliferation. Cancer Res 69:2615-22
Ju, Jeong Ho; Maeng, Jin-Soo; Lee, Duck-Yeon et al. (2009) Interactions of the acidic domain and SRF interacting motifs with the NKX3.1 homeodomain. Biochemistry 48:10601-7
Markowski, Mark C; Bowen, Cai; Gelmann, Edward P (2008) Inflammatory cytokines induce phosphorylation and ubiquitination of prostate suppressor protein NKX3.1. Cancer Res 68:6896-901
Bowen, Cai; Stuart, August; Ju, Jeong-Ho et al. (2007) NKX3.1 homeodomain protein binds to topoisomerase I and enhances its activity. Cancer Res 67:455-64
Rodriguez Ortner, Elizabeth; Hayes, Richard B; Weissfeld, Joel et al. (2006) Effect of homeodomain protein NKX3.1 R52C polymorphism on prostate gland size. Urology 67:311-5
Ju, Jeong Ho; Maeng, Jin-Soo; Zemedkun, Micheas et al. (2006) Physical and functional interactions between the prostate suppressor homeoprotein NKX3.1 and serum response factor. J Mol Biol 360:989-99
Shand, Randi L; Gelmann, Edward P (2006) Molecular biology of prostate-cancer pathogenesis. Curr Opin Urol 16:123-31
Zheng, S Lilly; Ju, Jeong-ho; Chang, Bao-li et al. (2006) Germ-line mutation of NKX3.1 cosegregates with hereditary prostate cancer and alters the homeodomain structure and function. Cancer Res 66:69-77
Asatiani, Ekatherine; Huang, Wen-Xin; Wang, Antai et al. (2005) Deletion, methylation, and expression of the NKX3.1 suppressor gene in primary human prostate cancer. Cancer Res 65:1164-73
Mani, Aparna; Gelmann, Edward P (2005) The ubiquitin-proteasome pathway and its role in cancer. J Clin Oncol 23:4776-89

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