Alan M. Gewirtz, M.D.
C. Willard Robinson Professor of Hematology/Oncology
Leader-Hematologic Malignancies Program, UPCC

Gene Therapy and Vaccines Program

Address

716 Biomedical Rsch Bldg II/III (Office)
727 Biomedical Rsch Bldg II/III (Lab)
421 Curie Boulevard
Philadelphia, PA 19104-6160

Office tel.: 215 898-4499
Lab tel.: 215 898-5101
Fax: 215 573-7049
E-mail: gewirtz@mail.med.upenn.edu

Link(s)

Dr. Gewirtz, Dept. of Med, Hem/Onc Div.

Dr. Gewirtz, Center for Aids Research

Education

Colgate University: AB (Marine Biology), 1971.

State University of New York at Buffalo: MA (Microbiology), 1976.

State University of New York at Buffalo: MD, 1976.

Research Interests

• Hematopoiesis.

Key words:Oligodeoxynucleotides, Antisense, Hematopoiesis, Human Hematopoietic Cell Development, c-myb, RNA Inference.

Search PubMed for articles

Description of Research

The focus of my laboratory has been the cell biology of normal and malignant human hematopoiesis. The laboratory has had a long standing interest in the extracellular regulation of human hematopoietic progenitor cell growth, in particular cells of the megakaryocyte lineage. We have also played a prominent role in the development of "antisense" gene squelching methods which allow the role of specific genes in regulating blood cell development to be investigated. Most recently, we have received funding from the National Space Biomedical Research Institute to study the effects of the deep space radiation environment on hematopoietic cell development. It is our ultimate goal to use the knowledge gained in these studies to advance the development of more effective, and less toxic therapies for human leukemia.

Recent Publications

Nakata Y, Shetzline SE, Sakashita C, Kalota A, Rallapalli R, Rudnick S, Zhang Y, Emerson SG, Gewirtz AM. c-Myb Contributes to G2/M Cell Cycle Transition in Human Hematopoietic Cells  by Direct Regulation of Cyclin B1 Expression. Mol Cell Biol. 2007 Mar;27(6):2048-58. Epub 2007 Jan 22

Kalota, A, Karabon, L, Swider, CR, Viazovkina, Elzagheid, EM, Damha, M, Gewirtz, AM. 2'-Deoxy-2'-fluoro-b-D-arabinonucleic acid (2'F-ANA) Modified Oligonucleotides (ON) Effect Highly Efficient, and Persistent, Gene Silencing.  Nuc Acids Res 2006 34:451-61

Opalinska JB, Machalinski B, Ratajczak J, Ratajczak MZ, GewirtzAM.  Multigene targeting with antisense oligodeoxynucleotides: an exploratory study using primary human leukemia cells. Clin Cancer Res. 2005 Jul 1; 11(13):4948-54

Ptasznik A, Nakata Y, Kalota, A, Emerson SG, Gewirtz AM. Short interfering RNA (siRNA) targeting the Lyn kinase induces apoptosis in primary, and drug-resistant, BCR-ABL1(+) leukemia cells. Nat Med. 2004 Nov;10(11):1187-9. Epub 2004 Oct 24.

Shetzline SE, Rallapalli R, Dowd KJ, Zou S, Nakata Y, Swider CR, Kalota A, Choi JK, Gewirtz AM. Neuromedin U: a Myb-regulated autocrine growth factor for human myeloid leukemias. Blood. 2004 Sep 15;104(6):1833-40. Epub 2004 Jun 8.

Lab

Rotation Projects

Project #1: Disrupting the expression of hematologically relevant protooncogenes with antisense oligodeoxynucleotides (ODN) can yield functionally informative data with important translational significance. Based on work of this type, we have begun clinical trials with an antisense molecule targeted to the myb gene. Though our trials are still in Phase I, it is clear to us that while myb is a rational target, it is still less than perfect for treatment of hematopoietic malignancies because it is expressed by both normal and malignant cells. We propose to address this problem by developing a more in-depth knowledge of Myb biology in normal and malignant hematopoietic stem/progenitor cells. In so doing, our long term goal of making Myb-directed therapeutic strategies more rational, and more specific will be advanced. We have developed three specific aims which support our goal. These aims are as follows: 1. Identify Myb-regulated genes and the mechanism whereby these targets are transactivated: The myb gene encodes a transcription factor which is of critical importance in the development of both normal and malignant hematopoietic cells. We intend to identify physiologically significant targets of the Myb transcription factor using differential screening, expression assays, deletion and mutation assays, gel shifting/foot printing, and antisense disruption. New, potentially tumor specific targets for antisense mediated inhibition of tumor growth may be identified in this manner; 2. Further define how Myb functions by identifying interacting proteins: The activity of many transcription factors is regulated by interaction with other nuclear proteins. MYC-MAD-MAX, MYO-D-ID, p53-mdm2 are well known examples. Because the Myb protein has domains which are permissive of such interactions, we hypothesize that Myb function is also regulated by interaction with as yet unidentified binding partners. Using standard screening approaches, and a novel method based on flow cytometric screening for protein expression, we will identify physiologically relevant Myb binding partners. Novel therapeutic targets may also be discerned by this line of investigation; 3. Determine the effect of integrin-mediated lymphocyte adherence on c-myb expression: Integrin-mediated cell adhesion, through a process known as "outside-in" signaling, initiates intracellular signal transduction pathways that can modulate gene expression. Based on the important role played by myb in hematopoietic cell development, we hypothesize that integrin mediated interaction of hematopoietic cells with components of the extracellular matrix will modulate myb expression and the consequent downstream events which regulate hematopoietic development.

Project #2: Develop A Rational Method For Targeting Antisense Nucleic Acid (ASNA), and Models for Testing Their Behavior In Vivo. It is likely that improvements in ODN design will be required before highly reproducible and efficient modulation of gene expression is observed. In this context, we are discussing the targeting of ASNA molecules, including siRNA. It is straightforward that ASNA can only be effective if they hybridize with their mRNA target. Hybridization requires a single stranded loop of RNA but the location of such loops in a live cell is virtually impossible to predict because of the complexity of RNA folding in vivo and the association of RNA with intracellular proteins that may also block ODN access. To address this issue, we have developed self-quenching reporter molecules (SQRM) that signal only after hybridization to their target. Preliminary data using this fluorescence based system to probe c-myb mRNA suggest that it may be possible to map hybridization accessible sites in a rapid, "high throughput "manner. Based on RNA mapping studies, antisense nucleic acids will be synthesized and their ability to cleave mRNA targets, in comparison to "random" ODN will be evaluated in vitro, and in vivo using "wild type" leukemia cells obtained from our tissue bank core. This work should lead to development of candidate antisense molecules with enhanced gene modulating activity. We will test the activity of these molecules against wild type leukemia cells obtained from the tissue bank core in a NOD/SCID animal model system. Uptake, distribution, and clearance of the molecules from various fluid and organ compartments will be studied using a variety of hybridization and chromatographic techniques. Data will be analyzed as a function of time, dose, and schedule of drug administration in order to facilitate development of rational drug delivery and treatment protocols. Based on these data, as well as pharmacokinetic and pharmcodynamic data generated by Aim#1, we will then develop and test delivery strategies with the goal of having an improved therapeutic, and the means to deliver it to patients, by the end of the first 5 years of the SPORE's funding.

Lab personnel:

Monika Jasek - Visiting Scholar
Anna Kalota - Visiting Scholar
Yuji Nakata - Visiting Scholar
Cezary Swider - Visiting Scholar
Shenghao Jin - Postdoctoral Fellow
Susan Shetzline - Postdoctoral Fellow
Jyo Swaminathan - Postdoctoral Fellow
Huiwu Zhao - Postdoctoral Fellow
Steve Rudnick - PhD Student