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Arizona Cancer Center at the University of Arizona, Tucson
ARIZONA CANCER CENTER SPORE IN GI CANCER The American Cancer Society estimates that over 170,000 US citizens will develop gastrointestinal (GI) cancer this year; 100,000 will die. Led by cancers of the colon, esophagus and pancreas, GI cancers account for over 17% of US cancer deaths. The goal of this interdisciplinary Specialized Program of Research Excellence (SPORE) in GI Cancer at the Arizona Cancer Center (ACC) is to prevent and cure GI cancers. The SPORE approaches this goal through studies in prevention, genetics and therapeutics. In particular, the SPORE attacks the poor survivability linked to delayed detection. Project 1: Genetic variability as prognostic or predictive factors in colorectal interaepithelial neoplasia (IEN) and Project 2: Ablation of Barrett's esophagus in prevention of esophageal adenocarinoma, use knowledge gathered during clinical studies to address cancer risk, prevention and treatment. Project 3: MUC1-specific immunotherapy of colon cancer, Project 4: Redox mechanisms in colorectal cancer and Project 5: New molecular targets in colorectal and pancreatic cancers, all propose translating basic science achievements in cancer cell biochemistry into novel therapies. The projects are supported by six important core services. The GI Tissue Resource and Markers Core will collect, catalog, and analyze GI cancer tissue. The tissue bank and marker data will allow accelerated translation of research findings to patients and people at risk. The Clinical Resource compliments the ACC resources, consolidates clinical trial efforts, and implements human subject recruitment plans for the SPORE. The Informatics Core addresses the effective use of data obtained during SPORE research. The use of databases and web-page interfaces will allow efficient data sharing and communication between ACC SPORE team members, other GI SPOREs, other GI researchers, cancer patients, and the general public. The Biometry Core provides indispensable front-end design and back-end analysis of the SPORE research. The final core, Evaluation and Administration, is the critical feedback loop necessary for a productive SPORE. The Developmental Research Program will ensure that the most promising translational ideas are nurtured and funded. The complimentary Career Development Program will support and mentor physicians and scientists in translational research. Taken collectively, the ACC SPORE in GI Cancer offers a unique opportunity to prevent and cure GI cancer. The ACC SPORE is organized into 5 Projects and 6 Cores. The Projects and Cores are described below.
Project 1: Genetic Variability as Prognostic or Predictive Factors in Colorectal Intraepithelial Neoplasia
The translational goal of this project is to develop simple blood tests to predict colon cancer risk and to tailor therapy for colorectal intraepithelial neoplasia (IEN). Diagnosis of colon cancer at an early stage continues to be problematic, and response to treatment is limited in late stage colon cancer. Better measures of risk will contribute to colon IEN prevention or earlier detection. Earlier detection combined with methodologies to predict response to therapy will decrease colon cancer incidence and mortality. The hypothesis to be tested in this proposal is that the risk of colorectal cancer is influenced by genetic variability affecting the expression/function of the adenomatous polyposis coli (APC) tumor suppressor gene and/or APC modifier genes, such as ornithine decarboxylase (ODC). Measures of this genetic variability may be prognostic and/or predictive factors for colorectal IEN. To test this hypothesis, four specific aims are proposed. First, we will measure specific mutations in the APC tumor suppressor gene in colorectal adenomas from participants in colon cancer prevention trials. Second, we will measure germline polymorphism frequencies in codon 1822 of APC. We will determine associations between genetic variability in APC with dietary factors and adenoma recurrence in this patient group. Third, we will measure the genetic variability in the c-myc-dependent region of the ODC promoter in groups at risk for colorectal IEN, and determine whether polymorphisms are associated with ademp,a recirremce. Finally, we will ascertain the functional significance of these polymorphisms in intestinal carcinogenesis. Future studies will measure variability in other downstream mediators of APC. These other mediators include networks regulating polyamine and arachidonic acid metabolism. Since these pathways are targets for IEN therapy (e.g. DFMO, NSAIDs), genetic variability in these pathways may be predictive factors for therapeutic response to treatment. Project 2 Ablation of Barrett's Esophagus: Incomplete Ablation, Increased Cancer Risk and its Prevention Barrett's Esophagus (BE), a known precursor to esophageal adenocarcinoma, is an excellent model for the study of carcinogenesis in vivo. BE is a condition where columnar, metaplastic epithelium replaces the normal squamous epithelium and is associated with increased risk of cancer. Because approximately 1% of U.S. adults are estimated to have BE, the affected population is aproximately 2 to 3 million adults. One of the latest treatments for BE utilizes techniques to ablate or reverse this lesion back to squamous epithelium. While the use of ablation techniques is rapidly increasing in the U.S, a question that has never been answered is whether the cancer risk is reduced by these procedures. Our group was the first to raise this question and has published early data indicating that complete reversal, ie. with no signs of Barrett's columnar epithelium left behind, results in a lesion indistinguishable from normal squamous esophagus. On the other hand, partial reversal, where areas of columnar, metaplastic epithelium co-exist with squamous, produces regions of epithelium that appear quite abnormal and may indeed result in increased cancer risk. Incomplete ablation occurs in 22-57% of subjects, when they are endoscoped six months after the procedure. A compelling way to show an increased cancer risk would be a clinical trial, but this is not a practical undertaking, as is often the situation in premalignant diseases. Consequently, our approach has been to study biomarkers and their expression in BE tissue biopsies. Our preliminary data indicates that the post-ablation partially-reversed tissue has increased cyclooxygenase-2 (COX-2) expression. COX-2 overexpression contributes to apoptosis resistance, a situation that increases genomic instability resulting in mutations, some of which are carcinogenic. We have also found that the BE epithelial cells are resistant to apoptosis. We plan to evaluate the expression of COX-2 and other redox-associated proteins (eg. NF-kB, NOS2, bcl-2) that we have shown to be anti-apoptotic in the colon, for their upregulation in partially-reversed BE tissue. We also plan to evaluate the down-regulation of pro-apoptotic DNA damage response/repair proteins (eg. BRCA1, GADD153, PARP, p53) as risk factors for cancer in the esophagus. The long-term goals of our studies are to develop new biomarkers for assessing risk of cancer in BE patients, especially those undergoing ablation, and identify new intervention strategies to reduce this risk. Project 3: MUC1-specific immunotherapy of colon cancer Colorectal cancer is the second leading cause of cancer death in the United States. Conventional therapies including surgery, radiation and chemotherapy have shown limited success with an average 5-year survival of only 8% in patients with metastatic disease. Thus recent efforts have focused on cyclooxygenase-2 (COX-2) inhibitors to decrease the risk of colon cancer. These agents reduce the size and frequency of intestinal polyps in adenomatous polyposis coli (APC)-deficient mice and in humans harboring the familial adenomatous polyposis (FAP) mutation. However, cessation of drug therapy results in re-emergence of disease and subsequent mortality. With the goal of achieving durable responses, we propose a therapeutic approach that is antigen-specific and induces long-term tumor immunity. We have chosen to focus on MUC1, an epithelial mucin that is aberrantly expressed in colon cancer. MUC1 is recognized by cytotoxic T lymphocytes and therefore represents a unique target for antigen-specific immunotherapy. The goal of this project is to develop dendritic cell-based vaccines to treat MUC1-expressing adenomas and colon carcinoma in animal models and in colon cancer patients. The hypothesis to be tested is that spontaneously arising MUC1-expressing adenomas or colon carcinoma can be successfully treated using dendritic cell-based vaccines. The Specific Aims of this study are to: 1) develop human MUC1-expressing transgenic mice that spontaneously develop intestinal adenomas and carcinomas 2) develop effective MUC1-specific DC-based vaccines capable of preventing or abrogating adenomatous polyps and carcinoma, 3) conduct pre-clinical in vitro studies using DC-based vaccines to stimulate T cells isolated from colon cancer patients, 4) evaluate the ability of MUC1-specific, DC-based vaccines to induce immunologic responses in colon and pancreatic cancer patients. The MUC1-expressing mice will be generated by crossing the APCmin mouse (Min) or the PI3Kg null mouse (PI3Kg-/-) with a transgenic mouse expressing human MUC1 (MUC1.Tg). The Min mouse is a strain containing a fully penetrant mutation in the APC tumor suppressor gene leading to the spontaneous development of gastrointestinal adenomas by 3-4 months of age. PI3Kg null mice result from targeted disruption of the p110g catalytic subunit of phosphoinositide-3OH kinase(PI3Kg). As with human colorectal cancer, these mice develop spontaneous multifocal adenomas which progress to invasive colorectal adenocarcinomas. The proposed studies are expected to result in the development of novel DC-based vaccines for the prevention and/or treatment of colorectal cancer. Project 4: Redox Mechanisms in Colorectal Cancer Redox mechanisms play a key role in regulating the resistance of cancer cells to programmed cell death (apoptosis) and the growth of new blood vessels from pre-existing capillary beds (angiogenesis). A redox protein critically important to both processes is thioredoxin-1 (TRX-1). Trx-1 levels are increased in many human colorectal, gastric and pancreatic cancers. We have shown that increased Trx-1 expression in colon cancer cells inhibits apoptosis and stimulates the hypoxia-induced production of the angiogenesis stimulating vascular endothelial growth factor (VEGF). Trx-1 is necessary for hypoxia induced VEFG production by permitting increased levels of the HIF-1a transcription factor. In silico data mining has identified several potentially important single nucleotide polymorphism (SNP) sites in the human Trx-1 gene, including one SNP in the conserved catalytic site coding sequence. The hypothesis upon which the studies are based is that the increased expression of the Trx-1 in human gastrointestinal cancer inhibits apoptosis and stimulates angiogenesis leading to aggressively growing tumors with a poor clinical prognosis. Furthermore drugs that selectively inhibit the redox activity of Trx-1 will block these processes and can be used to prevent and treat colorectal cancer. Based upon this hypothesis the specific aims of the project are: 1) To investigate the relationship between Trx-1 expression, patient survival and response to treatment in a prospective study of Dukes C and Dukes D stage colorectal cancers. 2) To investigate Trx-1 single nucleotide polymorphism's (SNP) in normal and colorectal cancer patients. 3) To investigate mechanisms for increased angiogenesis by Trx-1 in colon cancer and 4) To investigate the mechanisms of inhibitors of Trx-1 in patients with colorectal cancer. The objective of our work is to conduct basic and translational studies on the redox regulation of gastrointestinal cancer progression and chemotherapy resistance and to use this information to develop more effective ways to prevent and treat gastrointestinal cancer. Project 5: New Molecular Targets in Colorectal and Pancreatic Cancers We have identified what we believe is the first small molecule that down-regulates c-MYC. We have compelling evidence that it is the interaction between TMPyP4 and the NHE III1 and the associated proteins involved in transcriptional activation that leads to down-regulation of c-MYC expression. In this project we propose to exploit the capability to down-regulate c-MYC with cationic porphyrins to treat patients who have either pancreatic or colorectal cancer. We will use in vitro and in vivo models to predict the best opportunities for therapeutic intervention using the optimum drug treatment protocols. In a parallel effort, supported by an RO1 grant, the mechanistic aspects of c-MYC down-regulation will be explored. Cyternex, Inc., a biotechnology start-up company, is involved in the optimization of cationic porphyrins for down-regulation of c-MYC, will supply the optimized cationic porphyrins for testing, and will also sponsor the preclinical pharmacology and toxicology. After completion of the in vitro and in vivo studies and selection of a lead compound, an IND will be filed and a phase I clinical trial conducted. Pancreatic and colorectal cancers have a mortality rate of 29,500 and 56,700, respectively, and we would expect an effective agent that down-regulates c-MYC to have a significant impact on both of these diseases. CORE A: Gastrointestinal (GI) Tissue Resource Core A-GI Tissue Resource will coordinate histopathological assessment of all GI tissues collected from three local Tucson-area hospitals and existing banks of normal and neoplastic GI tissues. Approximately 700 colorectal, esophageal and pancreatic cancer patients are seen annually at the Arizona Cancer Center (ACC), the Southern Arizona Veterans Administration Medical Center (SAVAMC) and Tucson Medical Center (TMC). Existing tissue banks contain over 5000 frozen and fixed samples of normal intestinal tissues, more than 1500 colon adenomas and over 800 specimens from patients with Barrett's esophagus have been collected and stored during the course of cancer prevention studies conducted at the ACC and SAVAMC. Standard methods of preservation and storing tissues will be employed to facilitate measurement of desired endpoints. Special services, such as laser capture microdissection, will be available. The activities of Core A-GI Tissue Resource will be coordinated with other proposed resources, to ensure collection of tissues from patients participating in the proposed clinical trials, standards of marker measurement in tissues, adequacy of statistical input into design of trials and evaluation of results from patient studies. With the assistance of Core E-Informatics, a comprehensive database for all samples within the GI Tissue Resource will be developed. This database will be designed so that it can be interrogated for patient related information, including outcome data, and specific prognostic and/or predictive factors obtained during the course of this research effort. Frozen and paraffin embedded tissue will be saved permanently. Prior to collection of tissue an informed consent will be procured. The consent will follow the guidelines established by National Action Plan on Breast Cancer (NAPBC) with approval and input from the Institutional Review Boards of the University Medical Center and the local participating hospitals. A Human Tissue Acquisition and Pathology Resource Committee, under the umbrella of the ACC, will be established to monitor this essential activity.
Core B: Markers The Markers Core will serve as a resource for the development and optimization of established as well as new methods for measuring research endpoints in the individual projects. In conjunction with the Human Tissue Procurement Service and the Biometry Cores, the Markers Core will develop and implement appropriate sample collection, tracking, storage and preparation procedures for human material collected during the course of this proposal. It is essential that biological samples be collected and stored appropriately to achieve good quality assay results. The Markers Core will serve as a resource for assay development, analysis and quantitation of immunohistochemical procedures in support of each project. Endpoints will include markers of cell proliferation, apoptosis, as well as potential prognostic and/or predictive factors under evaluation in the SPORE proposal. The prognostic and/or predictive factors will include assays for genetic variability (Project 1) COX-2 and NOS2 (Project 2), MUC-1 (Project 3), thioredoxin (Project 4) and c-myc (Project 5). The Tissue Service will be essential to the Markers Core for pathologic assessment of GI tissues and for obtaining tissue sections required for assays. The Markers Core will also work closely with the Biometry Core to maintain and evaluate quality control measures. Quality control measures will be an important component of the Markers Core and will be established for each assay. Historically, the Core has done a ten percent repeat of study samples to assess reproducibility.
Core C: Clinical Resources The long-term goal of the Clinical Core is to provide the expertise and infrastructure to assure the completion of all of the patient-based research studies proposed in this SPORE grant. The core goals will be achieved through accomplishing the following aims:
We intend to accomplish these aims by assembling a team of expert clinical investigators and clinical research stuff that will complement already existing clinical research effort here at the University of Arizona/Arizona Cancer Center. This resource core will be devoted to development and evaluation of new treatment approaches for patients with gastrointestinal malignancies. The core will supervise design and conduct of clinical trials for patients with gastrointestinal cancer, facilitate acquisition of pharmacokinetic and pharmacodynamic data, and supervise and facilitate acquisition of biologic samples from patients participating in clinical trials.
Core D: Biometry The goal of the Biometry Core is to collaborate with project investigators in the development and application of statistical methods for design and analysis. This goal is achieved through the following specific aims:
Biometry support is required in all phases of SPORE studies. During study design the core will address statistical power and sample size issues, and will work with study investigators to ensure that data collection procedures are appropriate to meet study objectives. During study recruitment and follow-up the core provides monitoring reports of study progress. Upon study completion, the core performs statistical analyses in collaboration with study investigators. Core personnel will also prepare and assist in the preparation of manuscripts for publication. The Biometry Core continues to be used by all program investigators in both clinical and laboratory settings.
Core E: Informatics The informatics core will provide broad internet-based services to the component projects and principal investigators of the spore grant including the establishment of needed databases, facilities for data entry, the computational tools for simple and complex queries of one or more databases, and computational support for sequence and microarray analysis. In addition, the core will provide a set of publicly web pages that describe the individual projects in a form that will be helpful and informative to cancer patients, their families and the general public. A more detailed and secure set of web pages will provide information to project scientists who may wish to perform a data search and analysis in order to build new hypotheses or to design new experiments. A longer-term goal of the informatics core will be to perform data warehousing of the information collected in this study so that data mining operations are possible, including evaluations of patient risk as revealed by the analysis of the genetic and biochemical properties of tumor tissue with patient demographics, history, therapy and survival. These operations will be designed to discover correlations and to produce predictive models of the data that may be useful in cancer diagnosis, prognosis and treatment. Thus, these long range goals of the informatics core will directly satisfy the translational goals of the spore grant.
Core F: Evaluation and Administration The American Cancer Society estimates that over 170,000 US citizens will develop gastrointestinal (GI) cancer this year; 100,00 will die. Led by cancers of the colon, esophagus and pancreas, GI cancers account for nearly 20% of US cancer deaths. The goal of this interdisciplinary Specialized Program of Research Excellence (SPORE) in GI Cancer at the Arizona Cancer Center (ACC) is to prevent and cure GI cancers. The SPORE will approach this goal through studies in prevention, genetics and therapeutics. In particular, the SPORE will attack the poor survivability linked to delayed detection. The SPORE is a large, complex program made-up of five primary projects, six supportive cores, a developmental research program with associated pilot projects and a career development program. In addition to the program components, the SPORE will sponsor seminars, journal clubs and workshops on translational research topics in GI cancer. Core F-Evaluation & Administration will be responsible for coordinating all SPORE activities. First, this core will provide important scientific oversight through the Executive Committee and the External Advisory Committee. The External Advisory Committee consists of experts in the fields of colon, esophageal and pancreatic cancer as well as lay expert advisors. The group will meet annually to evaluate the progress of the SPORE and provide direction for the future. Secondly, Core F will provide the essential administrative support needed to coordinate such an extensive program. |
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