Date Approved

2017

Document Type

Thesis

Degree Name

Master of Science in Molecular Pathology & Immunology

Department

Molecular Biology, Graduate School of Biomedical Sciences

College

School of Osteopathic Medicine

First Advisor

Joseph Nickels, PhD

Committee Member 1

Grant Gallagher, PhD

Committee Member 2

Salvatore Caradonna, PhD

Committee Member 3

Diane Worrad, PhD

Subject(s)

Adenosine, Regulatory T-Lymphocytes, Adenosine Diphosphate, Purinergic P1 Receptors, Immunity, Enzyme-Linked Immunosorbent Assay, Cytokines, Neoplasms, Tumor Microenvironment

Disciplines

Cancer Biology | Cell Biology | Immunopathology | Immunoprophylaxis and Therapy | Investigative Techniques | Laboratory and Basic Science Research | Molecular Biology | Neoplasms

Abstract

Ecto-5’-nucleotidase, known as CD73, is an extracellular enzyme that converts adenosine monophosphate (AMP) to adenosine and has recently been identified as a potential drug target for cancer immunotherapy. Its immunosuppressive effects, mediated by the activity of adenosine, are associated with higher rates of tumor invasion and metastasis, as well as poorer prognoses overall in many cancer types. CD73 is often co-expressed with ectonucleoside triphosphate diphosphohydrolase-1 (CD39), which catalyzes the conversion of adenosine triphosphate (ATP) to adenosine diphosphate (ADP), and ADP to AMP on the surface of tumor cells. Dual expression further propagates immunosuppressive effects of adenosine in the tumor microenvironment. Adenosine activates Adenosine Receptor 2A (A2aR), which suppresses T effector (Teff) cell expansion and function, while increasing the activity of T regulatory (Treg) cells. Upon inhibition of CD73, immunosuppressive adenosine is no longer released into the tumor microenvironment and an anti-tumor immunological response may be restored. This response is expected to include restoration of cytolytic T cell function and down regulation of Treg function. The development of cell based assays serves to augment the discovery of potent small molecule inhibitors of CD73 activity. Cell based assay optimization provides means to physiologically confirm compound hits, which were initially identified through HTS efforts. Several cell based assay techniques may be utilized for this purpose. In addition, systemic immune response may be monitored using a mixed leukocyte reaction and subsequent cytokine profiling by ELISA. This assay may be utilized as an alternative, more biologically relevant tool for profiling inhibitors of CD73.

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