The human Caveolin-1 (Cav-1) gene acts as a mammary gland tumor suppressor. We have previously identified Cav-1 inactivating (dominant-negative (DN)) mutations in up to 35 % of estrogen receptor (ER) positive breast cancer patients. Our hypothesis is that up-regulation of ER levels and activity are caused by Cav-1 inactivating mutations. As Cav-1 functions as an inhibitor of the Jak-2 kinase, we propose that Stat5a activation is the mechanism by which loss of Cav-1 function results in increased ER-alpha levels. In support of this hypothesis, we present novel evidence that Stat5a activation is sufficient to upregulate ER-alpha levels in ER-negative human breast cancer cells. As such, our preliminary studies have now defined a novel signaling pathway leading to breast cancer: Cav-1 gene inactivation (DN-mutations) -->Stat5a activation -->ER-alpha upregulation -->Cyclin D1 over-expression. The three Specific Aims of the project are: 1) Determine the role of Stat5a activation and ER-alpha in Cav-1-related mammary hyperplasia, proliferation, and 3D lumen formation. We will analyze the mammary glands of Cav-1/Stat5a double- knockout mice and study the ex vivo behavior of primary cultures of mammary epithelia from these mice. 2) Determine the role of Stat5a activation and ER-alpha in Cav-1-related mammary tumorigenesis and metastasis. For this purpose, we will perform orthotopic transplantation of Met-1 cells expressing Cav-1 dominant-negative (DN) mutants (such as P132L) that are found in human breast cancer. The role of Stat5a signaling will be assessed using DN mutants of Stat5a and Jak-2. The role of estrogen will be assessed by ovariectomy and supplementation with estrogen pellets. Tamoxifen-resistance will also be investigated. 3) Determine if Cav-1 mutations co-segregate with Stat5a activation in ER(+) human breast cancer samples. Here, we propose to examine the relevance of this newly defined signaling pathway in human breast cancer pathogenesis, using Cav-1 mutations, ER-alpha expression levels, and Stat5a activation as novel prognostic markers. Since greater than 40% of ER-alpha positive patients show tamoxifen-resistance, we will also examine if Cav-1 mutations and Stat5a activation are critical predictors of tamoxifen-resistance.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA098779-10
Application #
8006386
Study Section
Tumor Cell Biology Study Section (TCB)
Program Officer
Mohla, Suresh
Project Start
2003-01-23
Project End
2012-12-31
Budget Start
2011-01-01
Budget End
2011-12-31
Support Year
10
Fiscal Year
2011
Total Cost
$325,655
Indirect Cost
Name
Thomas Jefferson University
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
053284659
City
Philadelphia
State
PA
Country
United States
Zip Code
19107
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Capparelli, Claudia; Guido, Carmela; Whitaker-Menezes, Diana et al. (2012) Autophagy and senescence in cancer-associated fibroblasts metabolically supports tumor growth and metastasis via glycolysis and ketone production. Cell Cycle 11:2285-302
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