Paul M. Epstein, Ph.D.Associate Professor, Department of Cell Biology
|Ph.D.||Albert Einstein School of Medicine||Molecular Biology|
|Name of Award/Honor||Awarding Organization|
|Principal inventor on US Patent Application No. 20090105281 on “Methods of Treating Inflammation”|
|Principal inventor on US Patent No. 5,885,834 on “Synthesis of Antisense Oligodeoxynucleotide of Phosphodiesterase and Inducement of Apoptosis in Human Lymphoblastoid Cells|
|Fellow of the Rosalie B. Hite Foundation for Cancer Research|
|NIH Predoctoral Trainee|
|Scholarship for Woods Hole Marine Biological Laboratory Physiology Program|
|Dean’s List Columbia College||Columbia College|
|New York State Regents Scholarship|
Dr. Epstein's laboratory has been studying cyclic nucleotide phosphodiesterases (PDE), a large family of isozymic enzymes which control the cellular levels of two key signal transduction molecules, cAMP and cGMP, and thereby play a role in controlling a wide variety of critical cellular functions. Through cloning and sequence analysis, he is identifying different forms of phosphodiesterase and determining their expression and subcellular localization during normal development and in association with pathophysiological disease states. One disease sate he is concentrating on in particular is leukemia. He has found that a 63 kDa form of calmodulin-dependent PDE (PDE1B1) is expressed in leukemia cells but not in normal quiescent human lymphocytes. He cloned the cDNA for this gene and developed antisense oligonucleotides (ASODNs) against it. When he disrupts the expression of the gene for PDE1B1 with these AS ODNs, it triggers apoptosis in leukemic cells without any effect on normal resting lymphocytes. Hence these studies pioneer the basis for a possible new therapy for leukemia. Similar studies are now being undertaken with respect to breast cancer.
Not accepting lab rotation students at this time
Lab Rotation Projects
Most of the emphasis of the lab at the moment is identifying forms of PDE as targets for inducing apoptosis of cancer cells. We are also collaborating with two colleagues in Pharmacology, Drs. Joel Pachter and Stefan Brocke, to examine a potential role for inhibitors of PDE to strengthen the blood brain barrier as a means of treating Alzheimer’s Disease, and to examine a potential role for PDEs in regulating lymphocyte chemotaxis and transendothelial migration in relation to treating multiple sclerosis. Students are free to design their own projects, but possibilities are:
Project 1: We have found that stimulating the cAMP signaling pathway can overcome the resistance to inducing apoptosis in leukemic cells from patients that have developed glucocorticoid resistance (see: Tiwari, S. et al. “Type 4 cAMP Phosphodiesterase (PDE4) Inhibitors Augment Glucocorticoid-Mediated Apoptosis in B Cell Chronic Lymphocytic Leukemia (B-CLL) in the Absence of Exogenous Adenylyl Cyclase Stimulation.” Biochem. Pharmacol. 69:473-483, 2005). The mechanism of this effect is, however, still unknown. One hypothesis we have is that cAMP signaling may enhance the expression and/or function of the BH3-only proapoptotic proteins BAD and BIM, leading to apoptosis of these resistant cells, and this could be examined as a rotation project.
Project 2: Work from Dr. Pachter’s laboratory has pioneered a method for culturing primary brain microvascular endothelial cells (BMEC) in a manner in which the tight junctions of the endothelial cells are preserved (see: Song, L. and Pachter, J. S. Culture of murine brain microvascular endothelial cells that maintain expression and cytoskeletal association of tight junction-associated proteins. In Vitro Cell Dev Biol Anim, 39: 313-320, 2003). This therefore provides a model in vitro system in which to examine the effects of agents on the blood brain barrier. We hypothesize that PDE inhibitors will strengthen the blood brain barrier by enhancing the expression of expression of the tight junction-associated proteins, claudin-5, occludin, and zona occludin-1 (ZO-1), and this could be examined as a rotation project.
Project 3: PDE4 inhibitors have been shown to be effective in ameliorating the pathogenesis associated with multiple sclerosis (MS) in EAE animal models of this disease, though it is unclear how they work in this regard. We hypothesize that PDE4 inhibitors block T lymphocyte chemotaxis and transendothelial migration through their ability to induce phosphorylation and inactivation of rhoA resulting in decreased phosphorylation of myosin light chain, and, with the help of Dr. Brocke who is a renowned expert in this area, this can be tested in a rotation project.