Role of HIF-1 alpha in EcSOD-Induced Growth Inhibition of Pancreatic Cancer

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DESCRIPTION (provided by applicant): Adenocarcinoma of the pancreas is the fourth leading cause of cancer death in the United States and is increasing in incidence. Because of the poor therapeutic responsiveness of pancreatic cancer to surgery, chemotherapy, and radiation therapy, survival beyond five years is rare with median survival less than six months. Thus, novel and effective therapies directed against pancreatic cancer are needed to control progression and metastatic disease. Our studies have shown that scavenging superoxide with the antioxidant enzyme extracellular superoxide dismutase (EcSOD) or pharmacologically with the nitroxide compound tempol, have a strong tumor-suppressive effect in pancreatic cancer both in vitro and in vivo. New data presented in this proposal shows that overexpression of EcSOD leads to suppression of hypoxia inducible factor- 1a (HIF-1a). HIF-1a responds to reduced O2 availability by regulating crucial homeostatic processes such as angiogenesis, glycolysis, and erythropoiesis and has been suggested to be an important regulator of pancreatic cancer cell progression and survival. As a transcription factor, HIF-1 has more than 80 known target genes and the number continues 1. Determine whether the effects of EcSOD overexpression on pancreatic cancer cell growth inhibition are due to HIF-1a suppression by manipulating HIF-1a levels genetically and pharmaceutically. to increase. The current proposal will test the hypothesis that themechanism for the tumor suppressive effect of EcSOD and/or tempol is caused inlarge part due to the suppression of HIF-1 in pancreatic cancer and that this suppression is due to the removal of superoxide. In order to examine this hypothesis, we will address the following three Specific Aims: 2. Determine if pharmacological scavenging of superoxide in human pancreatic cancer cells with Tempol mimics the effects observed with EcSOD on HIF-1a. 3. Determine if Tempol-induced growth inhibition can be enhanced by chemotherapeutic agents (gemcitabine, 5-FU) in human pancreatic cancer. As reported in a recent NCI cancer bulletin article on pancreatic cancer, ¿the slow but steady march toward more individualized care in cancer medicine has left pancreatic cancer behind. Patients diagnosed with this disease live no longer today than patients diagnosed two decades ago, despite more than a dozen large clinical trials. Even as many patients with other cancers have benefited from targeted drugs, pancreatic cancer remains as deadly as ever¿ (http://www.cancer.gov/ncicancerbulletin/110309/page1). If we can rigorously demonstrate that the tumor suppressive effect of EcSOD and/or tempol is caused in large part by the suppression of HIF-1 in pancreatic cancer then the results of this proposed research program will provide a foundation for the rational design of a combined modality cancer therapy.