Significant advances as well productive failures have resulted from evaluation of chromatin remodeling as a target in advanced prostate cancer (PCA). Our group has recently proposed the role of histone deacetylase (HDAC) inhibitors as antiangiogenesis agents for PCA by demonstrating their effect on the modulation the transcriptional factor HIF-1 alpha (hypoxia inducible factor 1 alpha). The principal objective of the proposed research is to further determine the therapeutic potential of targeting HIF-1 alpha and angiogenesis with novel combination strategies involving HDAC inhibitors for the treatment of PCA. Our central hypotheses are that 1) targeting HDAC has shown preclinical and clinical activity in PCA; 2) HIF-1 alpha and angiogenesis are affected by HDAC inhibitors and other targeted therapies in PCA; and 3) there is a need to assess the selectivity of HDAC inhibitors and to determine optimal combination strategies in PCA. To this end we will pursue the following goals: 1) to further define the role of specific HDACs in the modulation of HIF-1 alpha and angiogenesis in PCA; 2) to evaluate novel combination strategies using xenograft models with targeted agents such as mTOR and microtubule inhibitors with antiangiogenesis activity likely to be enhanced by use of HDAC inhibitor; and 3) to conduct clinical studies with a rational combination strategy of HDAC and mTOR inhibitors in PCA. To achieve our goals we will pursue the following Specific Aims: Specific Aim #1 To assess the modulation of HIF-1 alpha and angiogenesis by specific HDAC isozymes in an in vitro PCA bone microenvironment model; Specific Aim #2 To determine the antitumor and antiangiogenesis activity of novel strategies targeting HIF-1 alpha with combination of HDAC, microtubule and mTOR inhibitors in in vivo PCA models; Specific Aim #3 To assess the biological and clinical activity of an antiangiogenesis combination strategy with HDAC and mTOR inhibitors in PCA patients. These studies are significant because they represent the development of rational combinations with HDAC inhibitors by exploiting both their transcriptional and non-transcriptional regulation of prostate tumor growth and angiogenesis. We expect that these studies will provide 1) new insights on the role of HDACs in prostate tumor microenvironment, 2) early clinical evidence that combining HDAC inhibitors and molecular targeted inhibitors increases the antitumor effects, and 3) the foundation for future clinical trials in PCA patients.