Pancreatic cancer is one of the most lethal cancers in humans. While immunotherapy clearly holds promise in this disease, it has been ineffective in most patients partly due to immunosuppression associated with regulatory Myeloid Derived Suppressor Cells (MDSC) and regulatory T cells (Tregs). Tumor-induced MDSC and Tregs are known to suppress anti-tumor immune responses. However, the molecular events controlling this process are not fully known. Src Homology Inositol Phosphatase (SHIP-1) deficient mice showed an expansion of MDSC and Tregs that negatively affect anti-tumor immunity. SHIP-1 expression is regulated by cytokines. In addition, SHIP-1 expression is developmentally regulated in T cells. Activated T cells induce MDSC expansion and function, however the mechanisms are yet unknown. Our preliminary data in a pancreatic TB model revealed that suppression of SHIP-1 protein expression is associated with the expansion of MDSC and Tregs, in vivo. However, we discovered that SHIP-1 expression was restricted to T-cells suggesting that the effects on MDSC accumulation may be indirect. The long-term goal of this proposal is to elucidate the role of SHIP-1 regarding the molecular interaction of MDSC and Tregs in a pancreatic tumor microenvironment. We hypothesize that pancreatic tumor-derived factors (TDF) suppress SHIP-1 expression in Tregs, which enable these Tregs to induce the activation and expansion of MDSC thus altering their function in pancreatic tumor microenvironments. Therefore in order to test our hypothesis, the following aims are proposed:
Specific Aim 1. To evaluate the effect of pancreatic tumor derived factors (TDF) on na?ve T cell polarization into Tregs and their expression/activity of SHIP-1, in vitro.
Specific Aim 2. To elucidate the molecular mechanism(s) by which TB Tregs induce MDSC in an orthotopic animal model of pancreatic cancer and in a spontaneous transgenic model of pancreatic cancer.

Public Health Relevance

Pancreatic cancer is a rapidly fatal disease and the fourth leading cause of cancer-related deaths in the United States. Unfortunately, current cancer therapies are partially ineffective due to the expansion of regulatory immunosuppressive Myeloid Derived Suppressor Cells (MDSC) and T Cells (Tregs). MDSC and Tregs suppress anti-tumor immune responses. Src Homology Inositol Phosphatase (SHIP-1) regulates MDSC and Treg expansion and function. Therefore, research findings from this pre-clinical study may lead to the discovery of novel molecular targets to develop better alternative therapies to combat and eradicate pancreatic cancer in humans.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Exploratory/Developmental Grants (R21)
Project #
3R21CA179668-01A1S1
Application #
8901349
Study Section
Special Emphasis Panel (ZRG1-OBT-Z (55))
Program Officer
Wali, Anil
Project Start
2014-05-21
Project End
2016-04-30
Budget Start
2014-07-01
Budget End
2015-04-30
Support Year
1
Fiscal Year
2014
Total Cost
$39,188
Indirect Cost
$12,975
Name
University of South Florida
Department
Biochemistry
Type
Schools of Medicine
DUNS #
069687242
City
Tampa
State
FL
Country
United States
Zip Code
33612