The overall goal of our SPORE is to reduce mortality associated with gastrointestinal (GI) cancers. This goal will be achieved through
identifying and developing interventions to modify molecular based common cancer-associated carcinogenesis and cancer progression
processes and linking them to human investigations.
Gastrointestinal Oncology SPORE
PROJECT 1: OMEGA-3 FATTY ACIDS AND COLORECTAL CANCER PREVENTIONCo-Principal Investigators:
Dean Brenner, M.D.
William Smith, Ph.D.
There is a need to identify and develop more favorable therapeutic index-based cancer preventive interventions. The overall goal of this project is to test the hypotheses that substituting w3 fatty acids for w6 fatty acids in colorectal mucosal membranes will sufficiently modify the ratio of eicosapentaenoic acid (EPA) to arachidonic acid (AA) available to prostaglandin-H synthases (PGHS)-1 and 2 to reduce local prostaglandin (PG) E2 concentrations. Reduction of colonic mucosal PGE2 will reduce the carcinogenesis stress and ultimately reduce the development of neoplasia in the colonic epithelium. We also hypothesize that the dose of fish oils sufficient to reduce local PGE2 can be predicted by plasma EPA: AA ratio and thus be individualized. The reduction of PGE2 concentrations sufficient to reduce proliferation and enhance apoptosis of the colorectal mucosal crypt may be search. AIM#1 will define the dose response to dietary fish oil in mice and the relationship between the plasma and colonic mucosal EPA:AA ratio upon reduction of PGE2 in colonic mucosa of PGHS-1 and -2 wild type mice will be fed diets formulated to match multiple human fatty acid intakes. The plasma and colonic musical EPA: AA rations and PGE2 concentrations in colonic mucosa and urine will be assayed. Date in AMI 1 will necessary to define the design of a Phase I clinical trial proposed in Aim 2. The clinical trial will determine if fish oil supplementation in humans on a normal diet can produce a colorectal mucosal and plasma EPA:AA ratio defined in the mouse models that will reduce colorectal mucosal PGE2, reduce colorectal crypt proliferation index and enhance apoptosis indicies. A Bayesian driven biomarker adaptive phase I design individualizes dose on the basis of individual biomarker response. The date obtained in this project will determine the feasibility, future design and biomarker endpoints of Phase II clinical trails with w3 fatty acids as potential preventives of colorectal adenocarcinoma. Project 1 tests the hypothesis that ?3 fatty acids, delivered orally as a fish oil formulation containing eicosapentaenoic acid ((20:5), EPA), will reduce local cellular PGE2 concentrations in a dose-dependent manner in rodent models and in normal human colorectal mucosa.
Specific Aim #1:
To determine the feasibility of increasing the colorectal mucosal EPA:AA ratio to levels sufficient to reduce colorectal mucosal PGE2 by 50% by varying doses of fish oil supplementation combined with diets that simulate usual and low-fat intakes in a mouse model.
Specific Aim #2:
To translate data obtained in Aims 1 and 2 to humans by:
b. Using these relationships to demonstrate that treatment with fish oil can be personalized to reduce colorectal mucosal PGE2 to a predetermined concentration.
PROJECT 2: MAKERS OF PANCREATIC CANCER USING A GLYCOPROTEOMIC APPORACHCo-Principal Investigators:
Mack Ruffin, M.D.
David Lubman, Ph.D.
Pancreatic cancer places a significant burden on society and has no effective early detection method. A glyco-microarray approach will be used to search for early detection biomarkers of pancreatic cancers in human plasma. We will use multi-dimensional liquid phase fractionation of intact N-linked plasma glyco-proteins previously isolated by lectin affinity columns. The multi-dimensional fractionation will involve non-porous chromatography to separate the glycoproteins and liquid capillary isoelectric focusing to separate protein isoforms, thus providing a means to collect isolated glycoforms in liquid phase for further analysis. UV absorption detection will allow profiling of changes between cancer versus control. Proteins of interest will be identified by mass spectrometry. These fractions will be spotted on nitrocellulose-coated microscope slides to produce a natural glycoprotein microarray, and will be interrogated by various fluorescently-labeled lectins to probe each microarray spot for the presence of different glycan moieties. Patients with pancreatic adenocarcinoma, pancreatic mucinous cystic neoplasms (MCNs) and intraductal papillary mucinous neo-plasms (IPMNs), chronic pancreatitis, Type II diabetes for 10 or more year, and normal patients will serve as the disease categories of interest. Plasma from 30 participants per category will be analyzed to search for patterns that can discriminate patients with MCNs/IPMNS from the other disease categories. Glyco-proteins that reveal such changes will be analyzed by QIT-TOF (MALDI-MSn) mass spectrometry to exam-ine the detailed changes in glycan structure that may serve as biomarkers. Once the potential bio-markers are identified, high throughput antibody arrays will be used to establish information necessary to plan a validation study. This will include initial analytical validation to define the within and between individual variability using 30 participants per disease category. Next, preliminary decision analysis will be per-formed on an open label set of assays from 50 participants per disease category. Finally, a blinded set of assays will be done on 95 participants per disease category. This systematic approach to examing the analytic characteristics of the assay will provide information required to plan a validation of these early detection biomarkers for pancreatic cancer. It is envisioned that these biomarkers could be used for early detection among high risk groups such a smoker, patients with long term Type II diabetes or chronic pancreatitis. Specific Aims: The basic aims of SPORE project #2 have remained the same. The specific aims are:
Define pancreatic cancer-related patterns in the glycoproteins present in serum using high-density glycoprotein arrays and mass spectrometry.
Develop high-density antibody arrays with fluorescently-labeled lectins that recognize different glycan structures in serum glycoproteins identified in Aim 1.
Perform preliminary clinical validation of high-density antibody arrays for use as early detection biomarkers for pancreatic carcinoma.
The outcome of this project will be early detection serum biomarkers for pancreatic cancer with data on within- and between-participant variance, ability to discriminate pancreatic mucinous cystic neoplasms (MCNs) and intraductal papillary mucinous neoplasms (IPMNs) from healthy adults, patients with long-term type II diabetes, patients with chronic pancreatitis, and patients with pancreatic cancer, and the necessary information to prepare for a definitive validation study. We have been able access serum samples of patients with obstructive jaundice who do not have any of the other diseases. We therefore modify our study design to include this disease group in discovery Aim 1.
PROJECT 3: MECHANISIM-BASED USE OF CHK1 INHIBITORS IN PANCREAS CANCERCo-Principal Investigator:
Theodore Lawrence, M.D., Ph.D.
Jonathan Maybaum, Ph.D.
A strategy showing great promise for treating pancreatic cancer is to combine cytotoxic treatments with agents that abrogate the already-tenuous checkpoint functionality exhibited by most tumor cells. Drugs that target the checkpoint protein Chk1 (such as AZD7762, currently in Phase-I clinical trials) are of particular interest in the context of pancreatic cancer because Chk1 has also been shown to have a critical role in mediating the activity of Rad51, a key protein in homologous recombination repair (HRR) that is associated with resistance to DNA damaging treatments, and is upregulated in human pancreatic tumors. The long-term goal of our work is to improve the outcome of patients with pancreatic cancer by rationally adding Chk1 inhibitors to the combination of gemcitabine (Gem) + radiation. Our preliminary data show that AZD7762 is a potent chemo- and radiosensitizer of human pancreatic tumor cell lines that both decreases HRR and abrogates the G2/M checkpoint. Specific Aim 1 is to determine the relative roles of cell cycle checkpoint abrogation and HRR inhibition in chemo- and radiosensitization by AZD7762. This work will allow us to identify mechanism-based molecular endpoints to be interrogated in future clinical studies, and to identify new targets for therapeutic intervention related to HRR activity. We hypothesize that checkpoint abrogation and HRR inhibition each play key but differing roles in chemosensitization (to Gem) and radiosensitization by AZD7762. Our preliminary results using both established cell lines implanted as xenografts and early passage human tumor xenografts also show that AZD7762 is a potent chemo- and radiosensitizer in vivo, providing strong motivation for conducting a clinical trial. Specific Aim 2 is to use xenograft models to establish the basis for conducting a clinical trial combining AZD7762 with Gem + radiation, evaluating the role of drug schedule. The results of Aim 2 will help to define the design of our subsequent clinical trial. Specific Aim 3 is to carry out a clinical trial using AZD7762 in combination with Gem + radiation in patients with resected pancreatic cancer. We will use a combination of Gem + radiation followed by Gem alone, combined with dose-escalating AZD7762, based on the schedule suggested in Aim 2. We hypothesize that the MTD for AZD7762 will be similar to that determined in the current phase I trials using Gem alone (i.e. that adding conformal radiation will have a minimal impact on the MTD of AZD7762 in combination with Gem). Also, we hypothesize that AZD7762 will inhibit Chk1 activity in surrogate normal tissues when administered at the MTD, and, possibly, at lower doses. Specific Aims: The long-term goal of our work is to improve the outcome of patients with pancreatic cancer by rationally adding Chk1 inhibitors to the combination of Gem and radiation. As originally submitted, the project contained three Specific Aims:
Determine the relative roles of cell cycle checkpoint abrogation and HRR inhibition in chemo- and radiosensitization by AZD7762 (a Chk1/2 inhibitor) (Years 1-5)
Use xenograft models to establish the basis for conducting a clinical trial combining AZD7762 with Gem and radiation (Years 1-2)
Carry out a clinical trial using AZD7762 in combination with Gem and radiation in patients with resected pancreatic cancer (Years 3-5)
PROJECT 4: ATDC AS A THERAPEUTIC TARGET IN PANCREATIC CANCERCo-Principal Investigator:
Diane Simeone, M.D.
Mats Ljungman, Ph.D.
Pancreatic cancer is a deadly disease characterized by late diagnosis, aggressive invasion of surrounding tissues, early metastasis, and resistance to therapy. The molecular basis of pancreatic cancer is incompletely understood. We have recently found that the majority of human pancreatic adenocarcinomas over express the gene for Ataxia-Telangiectasia Group D Associated (ATDC) and that ATDC functions as a novel oncogene by activating the ?-catenin signaling pathway (1). The ATDC gene was initially described in association with the genetic disorder ataxia-telangiectasia (AT) but was later found not to be the gene responsible for AT. We have found that overexpression of ATDC confers a growth advantage for pancreatic cancer cells both in vitro and in vivo. Furthermore, we identified ATDC as a novel DNA damage response gene that confers a survival advantage to pancreatic cancer cells when exposed to ionizing radiation (IR) and gemcitabine. We have shown that following DNA damage, ATDC is phosphorylated in response to gemcitabine and radiation at serine 550 (SQ motif). Loss of ATDC results in increased sensitivity to gemcitabine and IR-induced apoptosis and a defect in downstream cell cycle checkpoint signaling. In this proposal, we will investigate the role of ATDC in protecting pancreatic cancer cells against gemcitabine and IR and initiate a phase I clinical trial targeting ATDC in human pancreatic cancers. We propose that ATDC is a promising novel therapeutic target in pancreatic cancer because its inactivation is expected to lead to both reduced tumor growth and sensitization to the combination of gemcitabine and ionizing radiation (IR).In this proposal, we will explore the following specific aims: 1) the examine the role of ATDC in response to gemcitabine and IR in pancreatic cancer cell lines; 2) to assess the sensitizing effect of targeting ATDC in primary human pancreatic cancer xenografts grown orthotopically and treated with gemcitabine and IR; and 3) determine the efficacy and toxicity of ATDC knockdown using shRNA-containing nanovectors in a Phase I clinical trial.
Progress in Specific Aims:
Specific Aim 1:
Examine the role of ATDC in response to gemcitabine and IR in pancreatic cancer cell lines.
Specific Aim 2:
Assess the sensitizing effect of targeting ATDC in primary human pancreatic cancer xenografts grown at its orthotopic location treated with gemcitabine and IR.
Specific Aim 3:
Determine the efficacy and toxicity of ATDC knockdown using shRNA-containing nanovectors in a Phase I clinical trial.