The working hypothesis of our laboratory remains there is a convergence of prosurvival, angiogenesis and motility signals at common pathways in the local tumor microenvironment and thus these events can be efficiently targeted therapeutically. We have focused to two pathways identified in our previous studies: function of the BAG-3 stress co-chaperone protein, identified in our CAI studies, and progranulin (GEP), a growth and invasion factor for ovarian cancer, identified in our analysis of cDNA libraries from microdissected clinical ovarian cancer samples. We continue our studies of the protective effects of BAG-3 on cell stress in dissection of its sensitivity to staurosporine treatment. We have identified and are further characterizing two mechanisms of regulation of BAG-3 protein stability and therefore survival support functions. Ongoing work also is dissecting the phenotype of transfectants of wild type and deletion mutants of BAG-3 in adhesion, motility, and cytoskeletal reorganization. We have identified alterations in the activation status of the src>fak and src>cas pathways. Analysis is ongoing also on the changes in gene expression in these mutants. Findings are consistent with the observed reduction in xenograft aggressiveness with the deletion mutants. Lastly, clinical correlative studies using immunohistochemistry are ongoing to assess the relationship of expression in epithelial ovarian of BAGs 1, 3, and 4. Studies of the Drosophila homolog of BAG 3/4, evil, continue and transgenic flies are being characterized currently for phenotype. Contract yeast 2-hybrid and siRNA production are nearing completion and validation studies have begun. Our work in ovarian cancer identified GEP as a growth and survival factor. Current results indicate that GEP production is regulated by pathways activated by G protein-coupled growth factors known to be active in ovarian cancer, LPA and endothelin through a cAMP/EPAC/MAPK pathway. Downregulation of GEP with neutralizing antibodies causes apoptosis of ovarian cancer cells. We have further demonstrated that secretory leukocyte protease inhibitory factor, SLPI, is a partner protein of GEP and also necessary for survival of ovarian cancer cells in culture. Xenograft and mutation studies have commenced. Production of GEP and its subsequent activity may be part of a signal amplification cascade in ovarian cancer and is a logical target for molecular therapeutics. Clinical assessment showed a link between GEP expression in ovarian cancer malignant effusions and patient outcome. Thus, GEP and BAG-3 each have potential as molecular therapeutic targets in ovarian cancer and other solid tumors.
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