We have identified an imprinted tumor suppressor gene designated ARHI. ARHI encodes a small GTP-binding protein that belongs to the Ras/Rap superfamily, but that has the characteristics of a tumor suppressor gene despite 54-59 % homology to the Ras protooncogenes. ARHI is consistently expressed in normal breast epithelial cells, but is dramatically downregulated in more then 70% of breast cancers. Reexpression of ARHI inhibits growth and induces apoptosis of breast cancer cells. The overall goal of this project is to understand regulation and protein-protein interaction of ARHI in breast cancer.
In Specific Aim1, we will identify and characterize the protein complexes that downregulate ARH1 expression in breast cancer cells. We will identify methyI-CpG binding domain protein (MBD) proteins that promote binding of histone deacetylase (HDAC) and histone methyl-transferase (HMT) repressors to the ARHI promoter and negatively regulate gene expression. We will characterize the role of the E2F family proteins on ARHI transcription and their ability to attract HDAC and HMT.
In Specific Aim2, we will further characterize the impact of ARHI on Stat3 function. We have found that ARHI interacts directly with Stat3 and inhibits Stat3 activity in breast cancer cells. We will further characterize this novel protein-protein interaction.
In Specific Aim3, we will determine the role of ARHI in breast tumorigenesis by knocking down ARHI expression in normal and immortalized human breast epithelial cells. Using the RNAi technology, we will knock down ARHI gene expression to determine whether this will alter the growth of normal human breast epithelial cells or transform immortalized breast epithelial cells.
Our Specific Aim 4 is to evaluate ARHI gene therapy in combination with cytotoxic drugs for the treatment of breast cancer. We will attempt to demonstrate additive or synergistic inhibition of breast cancer xenograft growth with a combination of adenovirus-ARHI and cytotoxic drugs through different signaling. These studies will provide a new insight of breast tumorigenesis, and find the potentially useful therapy for breast cancer.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
2R01CA080957-04A2
Application #
6777706
Study Section
Tumor Cell Biology Study Section (TCB)
Program Officer
Okano, Paul
Project Start
1999-08-01
Project End
2009-05-31
Budget Start
2004-06-01
Budget End
2005-05-31
Support Year
4
Fiscal Year
2004
Total Cost
$215,175
Indirect Cost
Name
University of Texas MD Anderson Cancer Center
Department
Internal Medicine/Medicine
Type
Other Domestic Higher Education
DUNS #
800772139
City
Houston
State
TX
Country
United States
Zip Code
77030
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Huang, Shaoyi; Chang, In Soon; Lin, Wenbo et al. (2009) ARHI (DIRAS3), an imprinted tumour suppressor gene, binds to importins and blocks nuclear import of cargo proteins. Biosci Rep 30:159-68
Feng, Weiwei; Marquez, Rebecca T; Lu, Zhen et al. (2008) Imprinted tumor suppressor genes ARHI and PEG3 are the most frequently down-regulated in human ovarian cancers by loss of heterozygosity and promoter methylation. Cancer 112:1489-502
Feng, Weiwei; Shen, Lanlan; Wen, Sijin et al. (2007) Correlation between CpG methylation profiles and hormone receptor status in breast cancers. Breast Cancer Res 9:R57
Feng, Weiwei; Lu, Zhen; Luo, Robert Z et al. (2007) Multiple histone deacetylases repress tumor suppressor gene ARHI in breast cancer. Int J Cancer 120:1664-8
Yu, Yinhua; Luo, Robert; Lu, Zhen et al. (2006) Biochemistry and biology of ARHI (DIRAS3), an imprinted tumor suppressor gene whose expression is lost in ovarian and breast cancers. Methods Enzymol 407:455-68
Lu, Zhen; Luo, Robert Z; Peng, Hongqi et al. (2006) Transcriptional and posttranscriptional down-regulation of the imprinted tumor suppressor gene ARHI (DRAS3) in ovarian cancer. Clin Cancer Res 12:2404-13
Lu, Z; Luo, R Z; Peng, H et al. (2006) E2F-HDAC complexes negatively regulate the tumor suppressor gene ARHI in breast cancer. Oncogene 25:230-9
Rosen, Daniel G; Wang, Lin; Atkinson, J Neeley et al. (2005) Potential markers that complement expression of CA125 in epithelial ovarian cancer. Gynecol Oncol 99:267-77
Nishimoto, Arata; Yu, Yinhua; Lu, Zhen et al. (2005) A Ras homologue member I directly inhibits signal transducers and activators of transcription 3 translocation and activity in human breast and ovarian cancer cells. Cancer Res 65:6701-10

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