Representative Molecular Medicine
Co-Mentoring Projects

1. Timothy P. Bender, Ph.D. and Dr. Marcie McDuffie, M.D.
Lymphocyte homeostasis and autoimmune disease.
Dr. Bender's laboratory has a long standing interest in the role played by the c-myb protooncogene during lymphocyte development. However, gaining insight into c-myb function has been problematic due to the embryonic lethality of the homozygous null mutation. To get around this problem they have used the Cre/loxP approach to make conditional c-myb mutants. One very important finding made using these mice was that c-myb was not required for the proliferation of mature lymphocytes as previously thought. However, it is becoming clear that c-myb limits long term proliferation, apparently by controlling survival during proliferation. Of particular interest, mice lacking c-myb in developing B cells have greatly reduced output of new B cells from the bone marrow resulting in reduced numbers of peripheral B cells. As new B cells that lack c-myb try to reach homeostasis there appears to be a great deal of cell death and splenomegaly. These mice also accumulate autoantibodies. This project will offer the opportunity to examine the role of c-myb in regulating both B and T cell population dynamics both in terms of homeostatic mechanisms and development of immune function. It will also provide a novel model system to examine mechanisms that may be involved in the pathogenesis of autoimmune disease in man.

2. Jim Bennett, M.D./Ph.D. and Jeremy B. Tuttle, Ph.D.
Development of Novel Therapies for Treatment of Alzheimer's and Parkinson's Disease. These investigators have several projects relating to investigating the contribution of mitochondrial gene defects in development of neurodegenerative diseases such as Alzheimer's and Parkinson's. Studies include investigation of the role of mitochondrial dysfunction in the control of neuronal gene expression, defenses against free radicals, and the regulation of apoptotic cell death.

3. Dr. Victoria Camerini, Ph.D. and Timothy P. Bender, Ph.D.
Role of c-myb in regulating T-lymphopoiesis.
These investigators have made mice that are targeted for deletion at the c-myb locus by the Cre/loxP approach, which allows control of expression of the c-myb locus in space and time. Using these mice they can delete the c-myb locus at various times during T cell development and study the impact on T cell development as well as T cell mediated immune function. One role that has been postulated for c-myb during T cell development is the regulation of genes required for development of g/d T cells. This project will focus on mice that delete c-myb very early in T cell development, near the time that developing T cells commit to development along the g/d or a/b T cell lineages and assess the role of c-myb during this decision process as well as analyze the consequences to mucosal immunity which is of critical importance for understanding a variety of human diseases.

4. David Camerini, Ph.D., Brian Wispelway, M.D., Greg Townsend, M.D., Frank Saulsbury, M.D.
Pathogenesis of HIV.
These investigators have several projects investigating the pathogenesis of HIV including studies of cell-signaling, viral entry and replication of early and late state HIV-1 patient isolates. Of particular interest, studies thus far have identified several mechanisms that contribute to HIV-resistance in certain patients.

5. Daniel A. Engel, Ph.D. and Daniel Theodorescu, M.D./Ph.D.
Novel Prostate Cancer Therapies.
Drs. Engel and Theodorescu have begun a collaborative project to probe the molecular basis for the action of "PC-SPES" in treating prostate cancer. PC-SPES is a proprietary mixture of herbal extracts that has been found in several clinical trials to be effective in the treatment of prostate cancer. Using a library of yeast knock-out strains that represents the entire yeast genome, we are screening for genes that are required for the action of PC-SPES. Once specific genes are identified, mammalian cell experiments can be performed to test the relevance of these pathways to prostate cell regulation.

6. Victor Engelhard, Ph.D., Donald Hunt, Ph.D., and Craig Slingluff, Jr. M.D./Ph.D.
Development of Recombinant Vaccines of Cancer.
Drs. Engelhard, Hunt, and Slingluff have a long standing collaboration using high throughput proteomic approaches to identify unique antigens present on tumor cells that may be employed for developing anti-tumor vaccines. Dr. Hunt is a pioneer in development of mass spectrometric microsequencing methodologies, and has developed sophisticated proteomic sequencing methods with a throughput and sensitivity unparalleled in any other laboratory in the world. Using this methodology, they have identified unique antigens present on melanoma cells but not normal melanocytes. Using this information, these investigators have designed recombinant vaccines for treatment and/or prevention of development of malenoma that are currently in clinical trials. This technology is being extended to examine a wide range of different human tumors and offers tremendous potential for development of powerful new therapies in the battle against cancer.

7. S.L. Gonias, M.D./Ph.D. and K. Johnston, M.D.
Role of Proteases in Cancer Development and Metastasis.
The plasminogen activators, tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (tPA) were first recognized for their ability to activate plasminogen and thereby promote lysis of blood clots. Both of these agents, together with other proteins in the same functional class, have been utilized as therapeutics in various thromboembolic diseases, including heart attack and stroke. More recently, uPA and tPA have been recognized as ligands for cell surface receptors. These interactions trigger cell-signaling pathways and induce changes in important aspects of cell physiology, including growth, migration, differentiation and apoptosis. Drs. Gonias and Johnston wish to understand the entire spectrum of activities associated with the plasminogen activators, including their function in hemostasis and on a cell-biological level. Students working in this area will be exposed to state-of-the-art technologies in cell and molecular biology and to translational/clinical projects in which the function of the plasminogen activators is considered.


8. Federico Gonzalez-Fernandez, M.D./Ph.D. and Daniel A. Engel, Ph.D.
Gene Therapy for Ocular Cancer.
Drs. Gonzalez-Fernandez and Engel have initiated a joint project to develop adenovirus as a gene therapy vector for the treatment of superficial ocular cancers. Conjunctival epithelium is a natural target for human adenoviral infections. Due to this tropism, and the accessibility of the tissue, it may be possible to efficiently deliver therapeutic doses of viral vector to superficially growing occular tumors. Initial stages of the project involve the establishment of tumor lines derived from surgical specimens and virus growth and expression studies. Also a rabbit model for developing the delivery system will be used.


9. John Herr, Ph.D., William P. Irvin Jr., M.D., and Craig L. Slingluff, Jr., M.D.
Cancer Testis Antigens in Tumor Dysregulation.
Genes normally expressed only in the testis during gametogenesis may be dysregulated in various tumor types including metastatic melanomas and prostate cancer. This research program identifies such cancer testis antigens and evaluates their usefulness as biomarkers of tumor progression and as drug or vaccine targets.

10. Stuart Howards, M.D. and John Herr, Ph.D.
Sperm and Egg Proteomics and Contraceptive Drug Discovery.
This research program identifies novel testis and ovary specific gene products expressed during gametogenesis and tests their efficacy as contraceptive vaccines and/or as targets for drug discovery. The program interfaces with the high-throughput screening group at Schering AG, a major European pharmaceutical company, to design assays to screen new contraceptive drugs.

11. John A. Kern, M.D. and Joel Linden, Ph.D.
Use of Adenosine Analogs for Treatment of Spinal Coar Injury.
Researchers led by Dr. John Kern in the Department of Thoracic and Cardiovascular Surgery have shown that adenosine analogs protect the spinal cords of animals from injury resulting from ischemia. The application of this discovery to humans is particularly exciting for patients who suffer ischemic damage to the spinal cord following aortic surgery, and holds the potential for reducing the damage to the spinal cord as a result of traumatic injury.

12. Dr. Gary Kupfer, M.D. and Timothy P. Bender, Ph.D.
Identification of Myb target genes in leukemia and lymphoma.
The c-myb protooncogene is consistently deregulated in leukemia and lymphoma yet surprisingly little is understood about the structural requirements for transformation or the target promoters that are involved. Drs. Bender and Kupfer have recently developed a model in murine erythroleukemia cells that carry a dominant negative Myb (MEnT) transgene and interfering with Myb activity in these cells provides a sufficient signal for them to differentiate and cease proliferating. Thus, this model provides a system to identify and characterize Myb target promoters. This project offers an opportunity to biochemically study the regulation of transcription by Myb family proteins with an emphasis on identifying and characterizing not only sequence requirements in Myb target promoters but the protein binding partners that modify Myb family activity. A second project available through Drs. Bender and Kupfer is the study of c-myb structural requirements for transformation in B and T cell leukemia and lymphoma. This effort will involve producing transgenic mice that carry tissue specific expression cassettes for c-myb as well as a variety of c myb mutants and examining the structural requirements for transformation. In addition, this work will provide opportunities to identify c-myb target promoters as well as assess role of c-myb in the development of lymphocytic leukemia and lymphoma.

13. Joel Linden, Ph.D. and George Beller, M.D.
Development of Novel Adenosive Analogs for Treatment of Coronary Disease.
These investigators discovered that adenosine analogs, applied to animals following simulated heart attacks, dramatically reduced inflammation and cardiac damage. Reducing inflammation can limit the damage to the heart muscle and dramatically improve the ability of the heart to recover its ability to contract and pump blood. As such, these results may lead to exciting new therapies for treatment of heart attach victims.

14. Mark Okusa, M.D. and Joel Linden, Ph.D.
Use of Adenosine Analogs in the Treatment of Kidney Disease.
During surgical procedures, injury, or trans-plantation, blood flow to the internal organs is temporarily slowed (a process called ischemia). Mark Okusa, M.D., Assistant Professor of Medicine, has shown that administering adenosine analogs after ischemic injury can reduce inflammation and damage to the kidneys. The timely application of these compounds may be useful in protecting the kidneys following injury or surgery, and in protecting the abdominal lining from inflammatory damage caused by long-term dialysis of patients with kidney failure. The adenosine analogs are also believed to hold significant implications for the treatment of chronic kidney failure caused by diabetes and hypertension.

15. Mark Okusa, M.D. and Kevin Lynch, Ph.D.
Development of Novel Lysophorphatidic Acid Antagonistic for Protection Against Ischeimia-Reperfusion Injuary.
Dr. Okusa and I are exploring the role of lysophosphatidic acid (LPA) receptors in renal function. Specifically, Dr. Okusa has found that administration of our LPA receptor antagonist, VPC12249, to mice provides a remarkable degree of renal protection in an ischemia/reperfusion model. This discovery has prompted Dr. Okusa to probe further to understand the basis of this phenomenon. Together with Dr. T.L. Macdonald, Professor of Chemistry,they are investigating the efficacy of additional LPA antagonists in the VPC12249 series. Further, Drs. Okusa and Lynch are using in situ hybridization to map LPA receptor expression in the mouse kidney.


16. Gary K. Owens, Ph.D. and Ian Sarembock, M.B., Ch.B., M.D.
Gene Therapy for Coronary Disease.
Drs. Owens and Sarembock have had a long standing collaboration to investigate mechanisms of development of atherosclerosis the underlying basis of heart attacks that account for over 50% of all deaths in the United States. Projects include identification of molecular genetic mechanisms that contribute to development of coronary artery disease, and development of novel vascular smooth muscle gene targeting methods for investigating both mechanisms of development of coronary artery disease, as well as potential gene targeting therapies.

17. Sarah Parsons, Ph.D. and Corinne Silva, Ph.D.
Role of JAK/STAT signaling in the etiology of breast cancer.
P190RhoGAP is a multi-domain 190 kDa protein that localizes to the cytoplasm of cultured cells and appears to function as an inhibitor of cell proliferation and inducer of apoptosis. It contains a RhoGAP domain that activates the intrinsic GTPase activity of the Rho family of small GTPases, which regulate actin cytoskeleton rearrangements in response to growth factor or integrin stimulation. P190 is also tyrosine phosphorylated and a substrate of c-Src. Drs. Parsons and Silva are investigating the role of p190RhoGAP in regulating growth factor induced cytoskeleton rearrangements, cell cycle progression, and apoptosis and how tyrosine phosphorylation by c-Src affects these roles. Their preliminary results suggest that tyrosine phosphorylation of p190RhoGAP by c-Src reverses the inhibitory effect of p190 on cell proliferation. In other words, p190 may function as a tumor suppressor and c-Src may reverse this action.

The translational component of this project involves studies aimed at understanding the mechanism of the biological synergy between c-Src and the EGF receptor. c-Src and the EGF receptor are co-overexpressed in a variety of human tumors, including breast cancer, suggesting that the two tyrosine kinases may functionally interact and contribute to the progression of the disease. In murine fibroblasts and in human breast cancer cells, Drs. Parsons and Silva have shown that c-Src potentiates the tumorigenic capability of the EGF receptor by phosphorylating an amino acid residue in the kinase domain of the receptor, Tyr 845, that appears to be required for both the mitogenic and tumorigenic function of the receptor. They are currently examining the requirement for this phosphorylation in the ability of the receptor to participate in G-protein-coupled signaling pathways and to see if the paradigm extends to other EGF receptor family members, such as HER-2/neu. In other studies they have shown that c-Src is required for growth in serum of a panel of breast tumor cell lines. The intact SH2 domain and a catalytic-independent region of the kinase domain of c-Src are required for this growth. Efforts are underway to target the Tyr 845 of the EGF receptor and the SH2 and catalytic domains of c-Src for anti-cancer therapeutics.


18. Sarah Parsons, Ph.D. and Daniel Theodorescu, M.D./Ph.D.
Prostate Cancer. EGF-induced invasion in bladder cancer and VEGF-induced angiogenesis in prostate cancer.
Chromaffin cells are fully differentiated neuroendocrine cells of the adrenal medulla. They are derived from the neural crest and are studied as models for exocytosis. They secrete catecholamines in response to acetylcholine. C-Src is highly expressed in chromaffin cells, and we have found that c-Src and an associated protein tyrosine phosphatase (PTPase) participate in the regulation of the acetylcholine receptor channel activity. We are currently investigating the mechanism of the interaction between c-Src, the PTPase, and the receptor and elucidating downstream signaling pathways (which contain other tyrosine kinases and MAP kinase) that emanate from the receptor and that are dependent on c-Src or its family members. Some of these studies involve electrophysiological analyses and are being carried out in both chromaffin cells and HEK293 cells that ectopically express a functional acetylcholine receptor.

The translational component of this project involves studying neuroendocrine cell signaling in prostate cancer. Based on our studies in chromaffin cells, they became intrigued with the presence and potential role of neuroendocrine (NE) cells in cancers of the prostate. NE cells are normal constituents of prostatic epithelium, but their numbers increase when the epithelium becomes neoplastic and progresses into metastasis. Several laboratories have observed that mitotic activity of cells surrounding NE cells is heightened, as compared to other regions of the gland, suggesting that NE cells secrete paracrine growth factors. Existing evidence also suggests that in tumors, NE cells derive from the tumor cells themselves by a putative mechanism of "trans" differentiation. They are investigating the factors that regulate "trans" differentiation of LNCaP prostate tumor cells, whether differentiated NE cells secrete paracrine growth factors, and what mechanisms regulate secretion in these cells.

19. William Petri, M.D./Ph.D. and Barbara Mann, Ph.D.
Molecular Pathogenesis of Amebiasis/Human Genetic Susceptibility to Amebiasis
An estimated 40 million people suffer from amebiasis annually. Drs. Petri and Mann propose to identify immune mechanisms and genes that alone or in concert influence susceptibility to amebiasis. Over the last 3 years they have prospectively studied 300 children in an urban slum of Dhaka, Bangladesh. We have shown a 70% lower incidence of new Entamoeba histolytica infection in children with mucosal IgA antibodies against the carbohydrate recognition domain (CRD) of the parasite's adherence lectin. Surprisingly children with serum anti-Gal/GalNAc lectin IgG have a 50% increased susceptibility to amebic infection. Ongoing studies include an observational study to examine the persistence of acquired immunity. They will also address the question of why all individuals do not develop protective immunity by studying the influence of class I and II alleles on the anti-CRD antibody response associated with immunity. Additional studies will test the hypothesis that susceptibility to amebiasis associated with serum IgG anti-lectin antibodies is due to underlying genetic differences in children that predispose to E. histolytica infection. A family-based association study has demonstrated significant familial clustering of the serum anti-lectin IgG trait that appears to be unrelated to common environmental exposure. In addition the absence of the anti-lectin IgG trait is in most cases not due to lack of exposure to E. histolytica infection. The preliminary data is therefore consistent with genetic inheritance of the anti lectin IgG trait and susceptibility to E. histolytica infection. To disentangle the genetic and environmental factors in what is likely to be a complex or multifactorial disorder they will examine a number of biologically plausible candidate genes for their association with susceptibility to amebiasis. Successful completion of these studies has immediate practical applications for design of an amebiasis vaccine and has the potential to be generally enlightening for the study of host parasite interactions at mucosal surfaces.

20. Dr. Richard Santen, M.D. and Timothy P. Bender, Ph.D.
Myb family genes in breast cancer.
The Myb family of proteins consists of three proteins in mammals that function as transcription factors. The proteins have unique but overlapping patterns of expression. Interestingly, all three proteins have been implicated in either breast development or breast cancer yet very little is understood about the roles of these genes in breast development or breast cancer. For example, estrogen receptor positive breast cancers that retain high levels of c-myb expression are correlated with a favorable prognosis. Drs. Bender and Santen have made breast cancer cell lines that carry a dominant interfering c-myb transgene and found that expression of this protein inhibits proliferation. This project will involve deriving mice that will conditionally over express Myb family members in developing breast tissue followed by examination of the consequences breast development and propensity for breast cancer. These mice will also be used to assess the structural features of Myb proteins that may be involved in developing breast cancer. This project will also offer the opportunity to make mice that carry conditional c-myb mutations and allow deletion of the gene at specific times during breast development. In addition, breast cancer cell lines that carry a dominant interfering Myb transgene will be used to identify and characterize potential Myb target promoters. These promoters will offer the opportunity to biochemically assess mechanisms by which Myb family proteins function to direct transcription on physiologically relevant promoters.

21. Ian J. Sarembock, M.B., Ch.B., M.D. and Joel Linden, Ph.D.
Use of Adenosine Analogs to Prevent Post-Angioplasty Restinosis.
A team led by Cardiologist Ian Sarembock, M.D., has found that certain adenosine analogs dramatically prevent restenosis (the recurrence of blockages at the site of balloon angioplasty) by inhibiting the inflammatory process triggered by the procedure. Restenosis occurs in approximately 30% of all angioplasties, including those involving the placement of coronary stents. Adenosine analogs significantly reduced the incidence of this restenosis.

22. Dr. Dan Theodorescu, M.D/Ph.D. and Timothy P. Bender, Ph.D.
Organ specific of regulation of VEGF transcription in metastatic prostate cancer.
This project derives from Dr. Theodorescu's work, which has demonstrated that VEGF expression alters CaP cell growth in an organ specific fashion. Thus, interaction CaP cells with stromal cells from a variety of tissues alters expression of VEGF and may determine the metastatic potential of CaP cells. This project will identify VEGF promoter sequences that are involved in organ specific regulation of VEGF and the identification of transcription factors that are involved. The project plays to the particular strengths of both our labs and has very exciting implications for understanding prostate tumor cell biology as well as therapeutic approaches.

23. Jeremy B. Tuttle, Ph.D, and William Steers, M.D.
Pathophysiology of Urinary Tract Disease.
Drs. Steers and Tuttle have several projects relating to the control and pathophysiology to the lower urinary tract and sexual function, especially the neural control of these visceral systems. These include study of the mechanisms governing changes in mictruition reflexes with aging, genetic models of hyperactive voiding and the neurochemical basis of urinary incontinence.

24. Michael J. Weber, Ph.D. and Dan Theodorescu, M.D./Ph.D.
Molecular Mechanisms Underlying Development of Prostate Cancer.
Drs. Weber and Theodorescu are jointly studying the role of alterations in signal transduction in prostate cancer growth and metastasis. This includes studying mechanisms that control angiogenesis in prostate cancer, and the role of MAP Kinase signaling in this process and in invasion of these tumor cells.

25. Michael J. Weber, Ph.D. and Christopher Thomas M.D.
Signal transduction as a therapeutic target for brain, head and neck and brain cancers.
Dr. Thomas has been studying tumors that are deleted for PTEN, the PI3Kinase phosphatase important for regulating apoptosis. Dr. Weber has found a novel survival signaling pathway that appears in at least some PTEN negative tumors. Understanding this pathway provides a novel therapeutic target.