Project 1: Translating N-cadherin targeted therapy in castration resistant prostate cancer. (R. Reiter, A. Wu)
Castration resistant metastatic disease is the major cause of morbidity and mortality in men with advanced prostate cancer. The molecular mechanisms underlying metastasis and castration resistance are both varied and only partially defined. Novel targets and therapies directed against these targets are urgently needed to combat advanced prostate cancer. Likewise, rational combination therapies directed against multiple critical targets are urgently needed. We have recently identified and "credentialed" N-cadherin as a novel target that contributes to and is required for both metastasis and castration resistance in prostate cancer. We have developed and validated in preclinical studies a murine monoclonal antibody that targets N-cadherin. This antibody is able to block metastasis, inhibit growth, and delay castration resistance of multiple prostate cancer cell lines and xenografts in vivo. Preliminary studies have uncovered the signal transduction pathways by which N-cadherin and N-cadherin-targeted antibody may act. These data support the novel hypothesis that N-cadherin is a significant molecular driver of castration resistant prostate cancer (CRPC) and a novel target for treatment of advanced prostate cancer. The overall goal of this grant proposal is to translate N-cadherin-targeted antibody therapy to the clinic. To do so, we will first examine the relationship of N-cadherin expression to the androgen receptor (AR) and determine whether N-cadherin is able to mediate resistance to AR-targeted therapies. Next, we will evaluate rational treatment combinations that might augment or synergize with antibodies that bind N-cadherin. These combinations will be based on an examination of N-cadherin signaling. Third, we will generate a lead human(ized) antibody capable of entering the clinic and evaluate its toxicity, pharmacokinetics and therapeutic activity in preclinical models. At the end of this project, we should know who to treat with N-cadherin antibodies, how to optimize targeting of this pathway, and have a lead biologic that can be manufactured and taken forward into the clinic.
Project 2: PI3K and MAPK pathway inhibition therapies in metastatic cancer and CRPC. (H. Wu, M. Rettig)
The lethality of prostate cancer (PCa) is attributable to the metastatic castration resistant state (CRPC). Accordingly, an understanding of the biochemical and genetic alterations that drive metastasis and castration resistance offers the potential and promise of identifying molecular targets for therapeutic intervention. During the current SPORE funding period, we have made significant advances in the elucidation of key signaling pathways that mediate castration resistance and metastasis. To investigate the molecular underpinnings of metastasis in Aim 1 of our proposal, we will use our recently developed mouse model in which the PI3KIAKT and Ras/MAPK pathways are simultaneously altered, as seen in humans, in a prostate specific fashion. The double mutants spontaneously develop metastases, which are absent in mice with single pathway alterations. Thus, these mouse models will allow us to establish the role of interactions between the PI3KIAKT and Ras/MAPK pathways in the development of metastasis as well as castration resistance and screen for therapeutic agents that can prevent or delay metastatic progression. Our recent studies also identified a novel mechanism of PI3KIAKT activation in response to androgen deprivation therapy, which leads to castration resistant growth. Conversely, PI3K inhibition results in enhanced AR transcriptional output. Thus, the compensatory activation of one of these pathways in response to inhibition of the other represents a "built-in" mechanism of resistance to therapies aimed at targeting either one of these pathways in isolation and suggests that simultaneous inhibition of both the PI3KIAKT and AR pathways is necessary to achieve maximal anti-tumor effects and avert castration resistance. Based on this finding, a three-arm phase 2 randomized neoadjuvant pre-prostatectomy trial is designed (Aim 2) to target the PI3KIAKT and AR pathways alone or in combination and study the downstream signaling and transcriptional output. Associated with this trial, we will also test non-invasive imaging technologies for monitoring pathway alterations and target responses. The success of our proposed research will provide vital insight into and identify therapies for metastasis and castration resistance, two processes that render PCa lethal.
Project 3: Evaluating a novel strategy to target Trop2 in prostate cancer. (O. Witte, M. Rettig)
Men with advanced prostate cancer are treated with hormonal therapy, which leads to an initial response that inevitably recurs in the lethal form of the disease termed castration-resistant prostate cancer (CRPC). While the androgen-signaling axis is the predominant target for therapy in the field, pathways promoting survival and proliferation that are independent of the AR axis need to be identified for potent combinatorial therapeutic strategies. Importantly, therapies aimed at depleting stem/progenitor cell mechanisms, such as self-renewal, have not been adequately explored .We have recently discovered that the stem cell marker Trop2 is a new regulator of self-renewal and proliferation in the prostate and is strongly associated with a castration-resistant state. We have defined a mechanism of action for Trop2 through regulated proteolysis, leading to release of an intracellular domain, similar to activation of Notch. As Trop2 marks and regulates stem cells and is associated with castration-resistance, we propose that blocking Trop2 proteolysis/activation will inhibit stem-like capacities including self-renewal and proliferation and prevent disease recurrence. In this proposal, we will utilize clinical specimens, primary regenerated tumors and established cancer xenografts to evaluate Trop2 proteolytic processing as a therapeutic target for future clinical trials in prostate cancer. The goal of AIM 1 is to validate Trop2 as a target in clinical prostate cancer specimens by measuring Trop2, its proteolytic products and downstream effectors in prostate cancer subjects. The goal of A IM 2 is to determine the role of Trop2 in human prostate self-renewal and tumorigenesis, using a dissociated cell tissue recombination strategy to evaluate Trop2+ cells and Trop2 itself in genetically defined primary tumors in vivo. The goal of AIM 3 is to investigate mechanisms to target Trop2 in pre-clinical studies. These experiments will utilize genetic and chemical approaches to establish the role of Trop2 regulated proteolysis, and assess monoclonal antibodies for their ability to interfere with Trop2 processing and tumor growth.
Epidemiologic and preclinical studies support the role of a low fat diet and fish oil intake for the prevention and treatment of prostate cancer. A prospective pre-prostatectomy trial conducted by our group found that a low-fat diet with fish oil reduced proliferation in prostate cancer epithelium in radical prostatectomy specimens and we found that the RBC membrane omega-6/omega-3 (n-6/n-3) fatty acid ratio correlated with prostate tissue proliferation levels. Our collaborator, Dr. Olefsky, recently identified a G protein coupled receptor (GPR120) on macrophages that mediates the anti-inflammatory effects of EPA and DHA (omega-3 fatty acids in fish oil) and we identified GPR120 in prostate cancer stroma, in neutrophils, and macrophages. Based on these findings, we hypothesize that a low-fat diet with fish oil may confer its anti-inflammatory/anti proliferative effects on prostate cancer through prostatic stromal GPR 120 by modulating the tumor microenvironment. Based on our prior preclinical and clinical studies, we anticipate that a low-fat fish oil (LF/FO) diet will inhibit prostate cancer proliferation in men on active surveillance, that the RBC n-6/n-3 ratio will be a useful blood-based surrogate biomarker to monitor prostate cancer proliferation levels, and that subjects with higher GPR 120 levels in prostate tissue will have greater anti-proliferative effects in response to fish oil intake. Thus the Aims of our proposal are (1) To determine the contribution of GPR120 to prostate cancer proliferation in archived specimens (2) To determine if a LF/FO diet delays the development of prostate cancer, in part, through the GPR120 receptor by using PTEN and GPR120 knockout mouse models, and (3) to determine the efficacy a LF/FO intervention in men on active surveillance and identify potential surrogate biomarkers for prostate cancer proliferation. We will measure gene expression of GPR120 and related inflammatory pathways in laser captured stromal tissue from our previous clinical trial and correlate these findings with proliferation. A prospective trial will be conducted in 100 men on active surveillance randomized to a low-fat diet with fish oil supplements or to a control group and prostate biopsies will be analyzed for proliferation (Ki-67 index) and GPR120 receptor levels at baseline and 1-year.
The Administrative Core (R. Reiter, O. Witte) is responsible for the oversight and daily functions of the SPORE programs. It provides administrative support for grants and financial management; scheduling of meetings and seminars; and coordination of activities between the SPORE, the Jonsson Comprehensive Cancer Center, and other UCLA academic and administrative bodies. It has ultimate responsibility for the overall management of the budget and appropriate filing of budgetary information. It files progress reports and communicates with NCI, NIH, and outside agencies, as necessary, as well as the UCLA Office of Contracts and Grants. In addition, it ensures completion of necessary documents with regulatory agencies.
The Pathology Core (J. Said, J. Huang) provides essential services to all projects in the SPORE with major commitment to tissue acquisition and processing, tissue histology and analysis including specialized techniques, and pathology consultation. The core is fully committed to collaboration with other SPORE and NCI programs, including the National Biospecimen Network (NBN), the Inter-SPORE Prostate Biomarkers Study (IPBS) and the Detection Research Network (EDRN). The core will provide a full range of services including processing, fixation, embedding of human and murine tissues, routine histology, and specialized immunohistochemistry and in-situ hybridization studies. Particularly use will be made of high throughput techniques incorporating tissue arrays with samples related to outcome such as PSA recurrence metastasis. A computerized database will be maintained of well-characterized matched samples of normal and neoplastic tissues. This database is electronically linked to the clinical database maintained by the SPORE Biostatistics core and the Department of Urology. Core facilities include a histology laboratory, a fully automated immunohistochemistry laboratory, computerized instrumentation for quantitative immunohistochemistry, and a tissue array facility. One of the key contributions of this core is expert pathology consultative services. The Core's leadership have demonstrated expertise with prostate pathology, both clinical and experimental, involving human and murine tissue. The investigators will continue to work closely with SPORE investigators in experimental design, use of human and murine tissues, and analysis and interpretation of results.
The Biostatistics and Informatics Core (S. Horvath, R. Dennis, D. Elashoff) will provide support in two related areas: a) biostatistical analyses, statistical consulting, and study design and b) research data collection, management, reporting, and data sharing. Each of the projects will utilize the tools, infrastructure, and expertise provided by this core. In addition, the biostatistics and bioinformatics core will provide support in the area of data sharing and communication for inter-SPORE collaborations similar to the Inter-SPORE Biomarkers Study (IPBS). Integrating biostatistics, data management, and bioinformatics within the same core ensures a seamless data analysis, and data sharing for each of the projects. The core members have a demonstrated track record of close collaboration and effective support of clinical investigators. The Biostatistics Core is organized to assist investigators in all aspects of the organization of their data flow and in the choice and setup of database management systems.
In particular, this core aims to
The Imaging Core (A. Wu, D. Margolis, S. Raman) supports the in-vivo imaging needs of the projects of the UCLA SPORE in Prostate Cancer. The Imaging Core provides functional as well as anatomical imaging technologies to investigators to develop and implement new imaging tracers and technologies.
The goals of the Imaging Core are:
Pre-clinical imaging studies are centralized in the Crump Institute imaging facility, which houses two microPET scanners, a microCT, three Xenogen IVIS optical imaging system, and a new Maestro multispectral fluorescence imager. Ancillary facilities including radiolabeling lab and rodent housing, are adjacent. In 2007 the preclinical Imaging Facility relocated to new, spacious quarters in the California Nanosystems Institution building where it continued to expand its offerings to investigators in oncologic molecular imaging. Clinical imaging and evaluation of novel radiolabeled tracers is supported by the Ahmanson Biological Imaging Clinic in the Geffen School of Medicine. Key aspects of the provision of imaging services are quality control and data acquisition/storage/analysis, which the Imaging Core provides in order to ensure reliable access to the instrumentation and data.
Molecular imaging will provide better ways to detect cancer, and smarter ways to understand its behavior and select the most effective therapy. The Imaging Core helps all SPORE investigators to integrate imaging into their basic investigations, and to develop new ways to detect prostate cancer in patients.