Pancreatic SPORE Grant Research Projects
The Mayo Clinic Pancreatic Cancer SPORE has four translational research projects, all of which focus on cutting-edge approaches to the early detection and treatment of pancreatic cancer:
Project 1: Regulation of Pancreatic Cancer Cell Proliferation and Survival by GSK-3β
Principal investigators: Daniel D. Billadeau, Ph.D., and George P. Kim, M.D.
Collaborators: Fergus J. Couch, Ph.D., Jan van Deursen, Ph.D., Charles Erlichman, M.D., and Jim Woodgett, Ph.D., Samuel Lunenfeld Research Institute, Toronto, Canada
Although the underlying etiology and pathophysiology of pancreatic ductal cancer is poorly understood, there is an increasing body of published work suggesting that signaling pathways that control cell proliferation, differentiation and apoptosis are dysregulated in pancreatic cancer. The mechanistic experiments test the central hypothesis that overexpression of GSK-3β contributes to pancreatic cancer cell proliferation and survival and is thus a viable therapeutic target.
This project hypothesizes that:
- The GSK-3β gene is gained or amplified in a subset of patients with pancreatic cancer
- Oncogenic K-Ras signaling regulates the expression of the GSK-3β promoter through its effects on Ets-1, Ets-2 and AP-1 transcription factors
- C-Src is a regulator of GSK-3β protein overexpression
- GSK-3 is required for the development of pancreatic ductal adenocarcinoma in the LSL-K-RasG12D mouse model of pancreatic cancer
- Enzastaurin will inhibit GSK-3 function in vivo
To test these hypotheses, this project will:
- Determine the mechanism regulating the expression of GSK-3β in pancreatic adenocarcinoma
- Determine the requirement for GSK-3β in pancreatic cancer pathogenesis
- Perform a phase II study of enzastaurin and gemcitabine in untreated, metastatic pancreatic cancer patients with metastases amenable to biopsy
Together, these studies will provide invaluable information about the mechanisms regulating the expression of GSK-3β in pancreatic cancer, the role of GSK-3β in pancreatic cancer development and the effect of GSK-3 inhibition on the treatment of pancreatic cancer. Because there also is increasing evidence that GSK-3β may affect other human malignancies, information obtained in these studies might advance the understanding of this kinase in other neoplasms.
Project 2: Pancreatic Cancer-Associated Diabetes: Pathogenesis and Biomarkers
Principal investigators: Suresh T. Chari, M.D., and George G. Klee, M.D., Ph.D.
Collaborators: Gloria M. Petersen, Ph.D., Yogish C. Kudva, MBBS., Martin E. Fernandez-Zapico, M.D., and Claudio Cobelli, University of Padova, Italy
This project's long-term goal is to develop screening strategies to diagnose asymptomatic pancreatic cancer. Up to 80 percent of pancreatic cancer patients have hyperglycemia and diabetes, which is evident many months prior to the cancer diagnosis and improves following resection of pancreatic cancer. Conversely, older patients with new-onset diabetes have an approximately eightfold higher risk of having pancreatic cancer compared with the general population.
Recognition of new-onset diabetes as an early manifestation of pancreatic cancer could lead to diagnosis of asymptomatic early-stage pancreatic cancer. This project will take these clinical and epidemiological observations to the laboratory to understand the pathogenesis of pancreatic cancer-associated diabetes and identify its biomarkers.
This project has several aims:
Specific aim 1: To determine if β-cell dysfunction is an early and key defect in pancreatic cancer-associated diabetes: Diabetes occurs in insulin-resistant states when β-cells fail to compensate for impaired insulin action. The high prevalence of diabetes in pancreatic cancer implies high rate of β-cell failure.
The project team has developed a technique in humans to simultaneously assess β-cell function, insulin sensitivity, and hepatic insulin extraction using three radiolabeled glucose tracers. The team has used this technique to study patients with type 2 diabetes, impaired glucose tolerance and normal glucose tolerance.
The team will perform similar studies in pancreatic cancer to determine if β-cell dysfunction is an early and key defect in glucose metabolism in pancreatic cancer-associated diabetes.
Specific aim 2: To determine if adrenomedullin is the mediator of pancreatic cancer-associated diabetes: Adrenomedullin is a 52 amino acid peptide hormone expressed in normal human islets that inhibits insulin exocytosis from β cells. It is markedly overexpressed in pancreatic cancer, and its plasma levels are increased in pancreatic cancer-associated diabetes.
This project hypothesizes that adrenomedullin is the mediator of β-cell dysfunction in pancreatic cancer. In preliminary studies, the research team has been able to transmit diabetes from a human to SCID mice using a xenograft of pancreatic cancer from a patient with pancreatic cancer-associated diabetes, while a xenograft of pancreatic cancer from a patient with normal fasting glucose had no effect on glucose levels.
Through in vitro studies using INS-1, an insulinoma cell line, the team has observed that pancreatic cancer cell lines inhibit glucose-mediated insulin release. Using genetic and pharmacological methods to modulate the expression and action of adrenomedullin in these in vivo and in vitro models, the team will investigate the role of adrenomedullin in causing pancreatic cancer-associated diabetes.
Specific aim 3: To develop a predictive model for pancreatic cancer among patients with new-onset diabetes: Pancreatic cancer-associated diabetes is associated with high plasma adrenomedullin levels and with older age, obesity and family history of diabetes.
This project will measure plasma adrenomedullin, insulin and glucose levels as well as CA 19-9, the best known tumor marker of pancreatic cancer, in a large cohort (n=420) of patients with pancreatic cancer with and without new-onset diabetes, new-onset type 2 diabetes, and healthy patients.
This project will determine the performance characteristics of adrenomedullin as a biomarker of pancreatic cancer-associated diabetes and develop a predictive model for pancreatic cancer using laboratory, clinical and demographic predictive factors.
If a biomarker of pancreatic cancer-induced diabetes is identified, it will have immediate clinical impact as it will allow the research team to start screening for asymptomatic pancreatic cancer in the subjects with new-onset diabetes.
Project 3: Hedgehog and EGF Pathway Interaction: A Novel Approach for a Multi-Target Therapy in Pancreatic Cancer
Principal investigators: Martin E. Fernandez-Zapico, M.D., and Charles Erlichman, M.D.
Collaborator: Jennifer Low, Genentech Inc., San Francisco, Calif.
The goal of this project is to design studies that are both mechanistic and translational, taking advantage of the knowledge recently generated in the research team's laboratory. These data show a novel pathway that identifies the transcription factor GLI1 as a shared effector for both pancreatic oncogenic pathways, hedgehog (HH) and epidermal growth factor (EGF), engendering a prosurvival/anti-apoptotic function in pancreatic cancer cells.
The project will utilize a comprehensive translational approach — from molecules-to-cells-to animals-to-humans — for the molecular and cellular characterization of this pathway as well as the preclinical and clinical testing of its targeted inhibition.
The project's central hypothesis is that a novel functional interaction between the hedgehog and epidermal growth factor pathways regulates cell survival via a GLI1-mediated anti-apoptotic response and targeting of this pathway by a combination therapy will positively impact on the treatment of pancreatic cancer.
This project has several aims to address the hypothesis:
Specific aim 1: To characterize the role of the hedgehog (HH)-EGF-PI3-AKT-GLI pathway on pancreatic cancer cellular survival using luciferase and chromatin immunprecipitation assays as well as expression of the apoptotic regulators BCL-2, BFL-1/A1, and 4-1BB by PCR and Western blot.
The project will complement these studies with apoptosis assays to determine the biological relevance of the PI3K-AKT pathway in HH-EGF-GLI1 survival.
Specific aim 2: To examine whether targeted inhibition of the HH-EGF-GLI1 pathway results in specific molecular changes indicative of tumor response by assessing the effect of this combination therapy using the experimental technique magnetic resonance elastography (MRE) in a mouse allograft model.
The project will use genetically manipulated cell lines deficient in pancreatic cancer specific tumor suppressor gene.
Specific aim 3: To perform a phase I trial of the combination erlotinib (Genentech EGFR inhibitor) and GDC-0449 (Genentech hedgehog inhibitor) to define the maximum tolerated dose, dose-limiting toxicity, and effects on molecular endpoints in pancreatic cancer subjects.
The knowledge derived from these studies will help further the understanding of the complex network implicated in pancreatic carcinogenesis and may serve as a foundation for the development of new therapeutic approaches for pancreatic cancer.
Project 4: Optimal Immunotargeting of MUC1 for Pancreatic Cancer
Principal investigators: Peter A. Cohen, M.D., and Sandra J. Gendler, Ph.D.
Collaborator: Mary L. (Nora) Disis, M.D., University of Washington School of Medicine, Seattle, Wash.
The nearly global aberrant hyperexpression of MUC1 in human pancreatic cancer affords a ready opportunity to target this disease immunologically. While mouse data demonstrate the potential value of reversing tolerance to this self-antigen, therapeutic responses to MUC1-directed immunotherapy remain disappointing.
This appears to be due to the natural thymic deletion of high avidity responses to self-antigens, such as HER2neu and MUC1, and the persistence of only low avidity responses in the residual tolerized state. It is now possible to routinely reverse such tolerance to self-antigens by exposing T cells to antigen-pulsed dendritic cells.
This research team has also demonstrated that IL-12-producing dendritic cells can reverse tolerance and can also up-modulate T cell avidity to enable much enhanced targeting of tumor-associated self-antigens. Such reversal of tolerance, however, must occur within an integrated approach to immunotherapy.
This project and others have demonstrated that immunotherapy is most successful when:
- Such high avidity T cell responses are engaged
- Both CD4+ and CD8+ anti-tumor responses are recruited
- Compatible chemotherapy is also provided
The project hypothesizes that all three components can be achieved for pancreatic cancer through an integrated immunotargeting of MUC1. The research team will use previously validated algorithms to identify MUC1-derived promiscuous 15mers, which can stimulate both CD4+ and CD8+ high avidity T cell responses to MUC1 when presented in the context of IL-12-producing dendritic cells.
The nearly ubiquitous expression of MUC1 in pancreatic cancer, the broad immunogenicity of promiscuous 15mers regardless of patient HLA-DR haplotype, and the synergizing potential of gemcitabine constitute a promising immunotherapy strategy applicable to most patients with pancreatic cancer.
This project has two aims:
- Specific Aim 1: To optimize these components of therapy in a valid tolerized mouse model of MUC1-expressing pancreatic cancer
- Specific Aim 2: To identify the critical MUC1-derived immunogenic peptides essential to implement this integrated strategy in clinical trials