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The University of Texas M. D. Anderson Cancer Center
Project 1 Background: The major cause of death from prostate cancer is metastases that are resistant to conventional therapies. The establishment, progressive growth, and survival of metastases depend on the interaction of metastatic cells with host factors in the microenvironment that tumor cells can usurp. The establishment of adequate vasculature, i.e., angiogenesis, is an excellent example. Data from our laboratory have demonstrated that metastatic prostate cancer cells produce PDGF that binds to and activates the PDGF-R on tumor cells (autocrine) and tumor-associated endothelial cells (paracrine). Activation of the PDGF-R leads to cellular proliferation, angiogenesis, and upregulation of antiapoptotic-survival factors. These findings lead us to hypothesize that induction of apoptosis in tumor-associated endothelial cells by inhibiting PDGF-R activity can lead to a second wave of apoptosis in surrounding normal cells and tumor cells. We recently reported that systemic therapy with imatinib, in combination with paclitaxel or docetaxel, produced significant therapeutic effects on human prostate cancer growing in the prostate, lymph nodes, and bone of nude mice. A phase I trial of imatinib for patients with androgen-insensitive, heavily docetaxel-pretreated prostate cancer metastases to bone produced long-term responses in a significant fraction of patients, prompting the initiation of an ongoing multi-institutional phase II/III study. These encouraging results led us to investigate, in detail, the mechanism(s) that regulate the response of patients with advanced prostate cancer to imatinib. We propose here to determine whether systemic therapy with imatinib and docetaxel is directed primarily against PDGF-R phosphorylation on tumor cells or tumor-associated endothelial cells. The human prostate cancer PC-3MM2 line will be cloned to isolate cells that do or do not express PDGF or PDGF-R. The therapeutic effects of imatinib (in combination with docetaxel) will be studied in vivo. We predict that only tumor cells that produce PDGF and activate the PDGF-R on endothelial cells will respond to the therapy. Next, we shall determine whether the dephosphorylation of PDGF-R varies among patients with prostate cancer and whether it is predictive of response to and toxicity of the combination of imatinib and docetaxel. We shall refine a bioassay to monitor the extent of PDGF-R phosphorylation in surrogate tissue (hair follicles) and compared the results with those in tumor tissue. Another possible explanation for the variable response of patients to imatinib is the role of the osteoblast in promoting growth of tumor cells and modulating sensitivity to treatment. In vitro studies of the nature of the cross-talk between osteoblasts and tumor cells should address this question. The last possible explanation for the varied response to imatinib is the heterogeneity in expression of tyrosine kinase receptors. We shall examine the expression of EGF/PDGF and EGF-R/PDGF-R in a large number of clinical specimens of primary human prostate cancers and metastases in lymph nodes and bone to determine whether selection of EGF-R expressing tumor cells can be responsible for the resistance to imatinib therapy. Significance: Understanding the determinants of response to imatinib and docetaxel in clinical and experimental models of prostate cancer metastasis in bone will lead to the development of specific therapies and strategies for their application by optimization of dose, improved monitoring, and selection of patients most likely to benefit from combination therapies that target additional paracrine pathways implicated in prostate cancer progression in bone.
Project 2 We have developed an in vivo selection system in which phage capable of homing to tumors are recovered from a phage display peptide library after that library had been intravenously administered to patients. We used this strategy to target the receptor for interleukin 11 (IL-11), which is present at low levels in the normal prostate gland and is highly expressed in human prostate cancer metastases. Studies from our laboratory and others suggest that IL-11 is a "metastasis gene" that is functionally relevant in the progression of prostate cancer. We propose here to investigate the mechanisms by which IL-11 promotes prostate cancer progression within the bone microenvironment and to develop targeted therapy based on the delivery of pro-apoptotic peptides to the IL-11R . Here we propose (i) To study the induction and activity of IL-11 and the IL-11R during prostate cancer progression. We hypothesize that the expression and activity of IL-11 and its receptor are increasingly upregulated in the angiogenic vasculature, in tumor cells, and in tumor stroma during the various stages of prostate cancer progression. We will evaluate tissue sections from human prostate cancer tumors at different sites (primary and metastatic) and different disease stages by using antibodies against IL-11, IL-11R , and activated STAT3; (ii) To determine the nature of the angiogenic stimuli leading to upregulation and activation of the IL-11R in endothelial cells, pericytes, and tumor cells. The ability of tumor cells and known pro-angiogenic factors to induce the IL-11R expression and function will be examined with several assay systems. Tumor models in which receptor expression is restricted to specific compartments within the tumor microenvironment (e.g., endothelial cells, pericytes, tumor cells) will be evaluated; and (iii) To examine the biological properties of BMTP-11, a pro-apoptotic peptide targeted to the IL-11R, in a phase I trial. A proof-of-principle phase I trial, the first of its kind in humans, will be performed with up to 14 men with metastatic androgen-independent disease involving the bone to screen BMTP-11 for its toxicity and its ability to selectively target tumor via the IL-11R. The goal of this clinical study is to estimate the therapeutic index of BMTP-11 (in terms of its selectivity for cancer), which will serve as a basis for developing this approach as a treatment for metastatic prostate cancer. Relevance: The proposed experiments will clarify the roles of IL-11 and the IL-11R in angiogenesis within the bone marrow microenvironment and will lead to development of new antitumor therapeutic strategies in the context of prostate cancer bone metastasis.
Project 3 We have developed an in vivo selection system in which phage capable of homing to tumors are recovered from a phage display peptide library after their intravenous administration. Using this strategy, we have targeted receptors in prostate cancer vasculature and in tumor cells that can be selectively accessed from the circulation. We propose that target ligand-receptor pairs are suitable for generating ligand-directed tools for gene-based and peptide-based molecular imaging. Here we introduce two strategies for targeted imaging in prostate cancer. The first is based on a chimeric vector consisting of genetic elements from adeno-associated virus (AAV) and M13 bacteriophage. These AAV/phage chimeras [AAVP] display tumor-homing peptides that bind to receptors that mediate selective internalization of targeted phage in vivo. Such phage-based vectors are suitable for thymidine kinase based imaging of prostate cancer at the molecular level. The second strategy relies on a panel of homing peptides that localize selectively to tumors upon intravenous administration. Here, we propose to test and validate both systems in vivo, first in animal models and ultimately in patients. Our Specific Aims are:(i) To evaluate ligands and receptors for targeted imaging of primary and metastatic tumors in prostate cancer. We will evaluate peptide ligands recognizing prostate cancer associated molecular targets. These ligands will be validated and compared in vivo and ex vivo based on their ability to selectively target prostate cancer cells and angiogenic vasculature; (ii) To design targeted peptides for molecular imaging of prostate cancer. We will focus on peptide-based diagnostic imaging of prostate cancer. Our initial studies will focus on the imaging evaluation of 61Cu- or 68Ga-labeled GRP78-specific peptides for the detection of prostate cancer in orthotopic xenografts and metastatic models; and (iii) To assess the feasibility of detecting prostate carcinomas by using molecular-genetic imaging with GRP78-targeted AAVP-mediated, GRP78 promoter regulated expression of HSVtk as a signal amplification strategy. We will explore the hypothesis that ligand-directed gene delivery for prostate cancer targeting and molecular-genetic signal amplification is more sensitive than is using direct GRP78-specific radiolabeled peptides. Phage-based vectors containing tumor targeting peptides and the HSVtk gene under the control of the GRP78 promoter will be studied. Relevance: Targeted molecular imaging would represent a major advance in the management of prostate cancer. Given that many of our peptides and phage vectors target angiogenic vasculature as well as tumor cells, these studies are likely to enhance the effectiveness of imaging technology and bring important insights as to their utility in clinical settings.
Project 4 In the currently funded SPORE, we found that obesity and high-fat intake are associated with prostate cancer progression. To further the understanding of the mechanisms underlying these associations, we have developed this project to address two basic translational objectives: clinical prediction of human prostate cancer progression and identification of mechanisms for therapeutic targeting. We propose the following Aims to:
We believe that understanding the epidemiologic determinates of progression and the underlying biological mechanisms, and exploring the reversibility of the cancer-progression process will lead to novel interventions targeting these pathways in patients with prostate cancer. The information gained from these studies will translate into the design of future clinical trials in which dietary compounds (e.g., flavonoids), behavioral interventions (e.g., diet, exercise) and/or drugs that target specific genes such as IGF-1R and leptin are used to alter the natural history of prostate cancer.
Project 5 Prostate cancer (Prostate cancer) has a propensity to metastasize to bone. A characteristic of prostate cancer bone metastasis is the striking osteoblastic phenotype. This organ-specific cancer progression is mediated, at least in part, by paracrine factors secreted from prostate cancer cells and osteoblasts. Understanding the mechanisms that lead to the osteoblastic progression of prostate cancer in bone will enable us to prevent, predict, and treat bone metastasis. Towards this goal, we have developed a strategy to identify bone-metastasis-related factors from bone marrow supernatant samples from patients with prostate cancer. The first such factor identified, which we named MDA-BF-1, is a 45-kDa secreted isoform of ErbB3. We found that MDA-BF-1 is expressed in prostate cancer cells that metastasized to bone, but not in Prostate cancer cells that metastasized to the liver, adrenal gland, or lung, suggesting that MDA-BF-1 may mediate specific interactions between prostate cancer cells and the bone microenvironment. Functional analysis of MDA-BF-1 by ectopic expression of this factor in PC-3 prostate cancer cells converted those cells from a bone-lysing to a bone-forming phenotype upon injection into mouse femurs. Further, recombinant MDA-BF-1 stimulated the formation of bone in mouse calvaria cultures and induced osteoblast differentiation. These results suggest that MDA-BF-1 is a paracrine factor that mediates the osteoblastic progression associated with prostate cancer metastasis in bone. Our long-term goal is to understand the mechanism of bone metastasis from prostate cancer. The objective of this application is to determine the role of MDA-BF-1 in the metastasis of prostate cancer to bone. The central hypothesis of this application is that prostate cancer cells that express MDA-BF-1 will interact with osteoblasts in such a way as to increase metastasis of prostate cancer to bone. We plan to test our central hypothesis and accomplish the objective of this application by pursuing the following specific aims: Aim 1. Identify MDA-BF-1 induced osteoblast factors that promote prostate cancer growth in bone. We have already identified SPARC and biglycan through gene array analysis. We will assess their functions in promoting prostate cancer progression in bone. Collectively, the work proposed is expected to lead to a better understanding of the mechanisms by which prostate cancer establishes metastases in bone and to translate this knowledge into clinical application.
Core A The purpose of the Administrative Core of The University of Texas M. D. Anderson Cancer Center SPORE in Prostate Cancer is to provide continuous leadership and general administrative support of all activities related to the SPORE. The principal role of the Administrative Core is to expand the integration of investigators from diverse scientific disciplines who have joined the translational research effort in prostate cancer. The Administrative Core will facilitate the functions of all projects and cores. Director, Dr. Christopher Logothetis, will be assisted by Co-Directors Drs. Isaiah Fidler and Sue-Hwa Lin. Specific administrative functions required to ensure the success of the SPORE include: overall function, communication among investigators and leadership, compliance with institutional, governmental, and NCI regulations and requirements, regular communication and interaction with NCI leadership, data quality control, quality assurance monitoring, budgetary oversight, education, organization and management of all meetings including those of the Internal and External Advisory Committees and the Executive Committee, development and distribution of Executive Committee and other meeting minutes, preparation of reports, administration of Developmental Research and Career Development Programs, assistance with other peer-reviewed grants, coordination and maintenance of inter-SPORE relationships and communication, administration of Patient Advocacy program, support of outreach activities to minorities and medically underserved communities, and assistance with commercialization of products arising from this SPORE and the regulatory requirements in the development of Investigational New Drug applications. The Administrative Core will interact with the Biostatistics and Bioinformatics Core and the Specimen Core, which have been expanded to meet the evolving needs of SPORE investigators.
Core B The research proposals in the SPORE encompass a broad range of activities, including studies in cell lines, animal models, and clinical trials. These studies will generate a number of different types of data. To enhance efficient cooperation between projects, relevant data must be easily accessible, but stored in a secure manner with assurance of patient confidentiality. Data and information must flow smoothly between projects. Data quality and integrity must be assured by data audit and backup procedures. An efficient interface will facilitate information flow between the computational biology and data storage facilities provided by the Specimen Core and institutional database, which can involve high-throughput data such as microarray and proteomics expression profiling information. In order to meet these needs, the Biostatistics and Bioinformatics Core brings together a number of biostatisticians, bioinformaticians, and other professionals with expertise in a number of statistical and data management disciplines. The Biostatistics and Bioinformatics Core will continue to incorporate sound experimental design principles within each projects that will enhance interpretability of study results, will carry out data analyses using appropriate statistical methodology, and will contribute to interpretation of results through written reports and frequent interaction with project investigators. The Biostatistics and Bioinformatics Core will further provide an integrated data management system to facilitate communication among all projects and cores, which will be customized to meet the needs of the Prostate SPORE. This process includes prospective data collection, data quality control, data security, and patient confidentiality. Thus, from inception to reporting, translational experiments will benefit from SPORE resources that will be used to augment existing M.D. Anderson Cancer Center biostatistics resources. The specific aims of the Biostatistics and Bioinformatics Core are:
Aim 1. Oversee and provide the design of clinical trials and translational experiments arising from the ongoing research of the SPORE.
Core C The Specimen Core will provide SPORE investigators with well-characterized biological specimens, including tissues, blood, and tissue derivatives, essential for achieving the aims of the projects. The Specimen Core has a large repository of paraffin blocks, frozen samples, plasma, serum, and bone marrow that spans the entire spectrum of prostate cancer. The repository includes primary tumors and metastases from therapy-resistant tumors and tumors derived from radical prostatectomy specimens from patients given novel neoadjuvant therapies as part of protocols conducted at The University of Texas M. D. Anderson Cancer Center or other multi-institutional efforts before and within the previous SPORE funding period. This material, supplemented in select cases with matching biopsy specimens, plasma, serum, and bone marrow aspirates collected before therapy, will provide M. D. Anderson Cancer Center Prostate SPORE investigators with optimal tissue samples with which to address the proposed basic and translational research tissue requirements of the Projects. Tissue requests and approval by the Tissue Acquisition and Distribution Committee are handled electronically. Tissue derivatives, including tissue microarrays, cRNA, and DNA, will optimize the use of limited samples and enhance collaboration among investigators at M. D. Anderson and other institutions. Structured information derived from standardized, high-throughput assays of differential gene expression, both of protein (immunohistochemistry) and RNA (oligonucleotide arrays and multiplexed PCR), will be available to individual SPORE investigators to facilitate modular and gene network analysis in specific clinical contexts. A unique feature of the Specimen Core will be the ability to link comprehensive clinical and pathological information to the morphologic and molecular characterization of selected pathways. This linkage will be accomplished, in cooperation with the Biostatistics and Bioinformatics Core, by designing a web-based Prostate Tissue Information database built on the institutional Clinical Research Information System (CRIS). By using this web-based informatics system, we will pool laboratory resources, facilitate the translational research proposed in the projects, and accelerate successful achievement of the proposed aims.
i. American Cancer Society. Cancer Facts & Figures-2002. Atlanta GA: American Cancer Society, Inc; 2002. |
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