Research Description

Our team is pursuing mechanisms to induce in vivo activated NK cells to provide anti-tumor benefit. This work usesthe strategy of Antibody Dependent Cellular Cytotoxicity (ADCC), whereby tumor reactive monoclonal antibodies can home in vivo to sites of tumor, and facilitate in vivo tumor destruction by IL2 activated NK cells. In murine experimentally induced syngeneic tumor models we are evaluating the efficacy and mechanisms that enable immune interventions to induce in vivo tumor destruction. This work involves treatment with tumor reactive monoclonal antibodies and their genetically engineered derivatives. Most recently, we have been investigating fusion proteins created by fusing humanized antitumor mAbs to human IL2. We have completed a single institution Phase I trial of the hu14.18-IL2 molecule in adults with melanoma at the University of Wisconsin Comprehensive Cancer Center (UWCCC), and a Phase I trial in children with neuroblastoma, through the Children’s Oncology Group.Potent in vivo immunological activation has been observed, including clear demonstration that the circulating hu14.18-IL2 molecule has activated NK cells in vivo, and can enable them to mediate tumor reactive ADCC.Phase II successor protocols have been approved by the NCI and should be open in 2005.

The major aim of my laboratory is to understand the way the nervous system controls behavior.  We now know that the "simple nervous system" of the nematode Ascaris has much more complexity than was ever imagined--the chemical signaling system it uses are very diverse, and we are sorting them out. These signaling systems include the neuropeptides, which we are devoting a major effort towards identifying and sequencing; other signaling systems that we have worked on include serotonin and glutamate, both of which play an important role in the motor nervous system. These signaling systems typically are involved in the process of neuromodulation, and each chemical involved affects the system in a different way.  Some produce profound effects on the neurons they influence, and others have subtle effects. Different chemicals affect different subsets of neurons. Neuromodulation is a matter of details, but the details matter.

We are developing new techniques for identifying peptides in a complex mixture.  I am currently excited about a new class of antibodies that we are developing.  These are generic antibodies that recognize specific C-terminal dipeptide sequences, and we have found many new types of neurons that contain peptides recognized by these antibodies, implying that they contain novel peptides.

Many classes of DNA rearrangements occur in all cells and play important roles in gene regulation, development, carcinogenesis, and evolution. The goal of this laboratory is to understand how these genetic rearrangements come about. The approach is to study in detail the isolated enzymes that play central roles in different classes of genetic recombination events. Currently, two systems are under investigation: recombinational DNA repair in E. coli and the extraordinary repair of double strand breaks during chromosome restoration in the bacterium Deinococcus radiodurans after heavy doses of ionizing radiation.

The RecA protein is the key component required for recombinational DNA repair in bacteria. This protein is capable of pairing two homologous molecules of DNA, exchanging strands of DNA between them. The reaction occurs in several phases that are easily distinguished experimentally. Our efforts are directed at: 1) a study of the structure of a putative 3-stranded DNA pairing intermediate, and 2) a determination of the mechanism by which complexes of RecA protein bound to DNA promote a unidirectional DNA strand exchange reaction coupled to ATP hydrolysis. The system offers a variety of unique problems on protein-nucleic acid interactions, unusual DNA structures, and biochemical energetics. 

We are investigating the molecular mechanisms of eukaryotic gene expression, with emphasis on transcription and pre-mRNA splicing. Our work focuses both on the nature of biomolecular interactions (protein:DNA, protein:RNA and RNA:RNA) and on the manner in which these interactions cooperate to direct complex processes such as RNA synthesis and processing. We have chosen the genetically and biochemically tractable yeast S. cerevisiae as a model system. Our transcription studies have centered on the influence of chromatin structure on promoter recognition in vivo by RNA polymerase III, which specializes in the synthesis of small RNAs. Recently, we have begun to also study the influence of RNA-binding proteins on transcription elongation by RNA polymerase II. The function of U6 RNA and associated factors in splicing of pre-mRNA is another major interest of my lab. U6 RNA experiences large conformational changes during its interactions with other RNAs in the splicing cycle. We are examining the mechanism and function of these dynamic interactions.

Research Description: Stem Cell Biology, Molecular Hematology, and Vascular Biology: From Fundamental Mechanisms to Translational Medicine

We use multidisciplinary, integrative approaches to understand important biological processes, including stem/progenitor cell function, blood cell development (hematopoiesis), and vascular biology. Such approaches include genomics, proteomics, chemical genetics, and computational analysis, as well as traditional molecular, cellular, and biochemical methodologies. In addition to elucidating biological principles, we aim to develop innovative therapeutic strategies based on targeting novel mechanisms.

A major project is to dissect mechanisms that regulate hematopoietic stem cell differentiation into specific progenitor cells, which in turn, form the specific blood cell types.  Defining such mechanisms has enormous importance, as deviations from hematopoietic programs lead to the development of leukemias, lymphomas, myelodysplasias and additional blood disorders.  Furthermore, while hematopoietic stem cells are routinely transplanted to treat diverse diseases, their therapeutically desirable long-term repopulating activity is poorly understood and cannot be readily modulated.  Thus, we are analyzing the function and regulation of GATA transcription factors that control hematopoietic stem cell function, hematopoiesis, the function of specific blood cell types, and additional important biological processes.  

We are interested in all aspects of picornavirology. Among our major goals are to explore and define the relationship of the cardiovirus genus to other members of the picornavirus family and to exploit the unique features of the cardioviruses to examine molecular questions about picornavirus translation, proteolytic processing, morphogenesis and pathogenicity. In contrast to many other viral genomes, cardioviral RNA is translated with unusually high efficiency in cell-free extracts. This provides a unique experimental system for examining viral protein expression and virion assembly. Everything we have learned about the molecular biology of these viruses provides an experimental foundation for study of the more virulent isolates such as foot-and-mouth disease virus, polio, coxsackie, hepatitis A, rhinovirus, etc. Isolates of Theiler's virus (murine encephalomyelitis), for example, and variants of EMC (encephalomyocarditis) are being studied as models in human diseases like multiple sclerosis and forms of insulin-dependent diabetes.

Our laboratory has developed an extensive panel of infectious cardiovirus cDNAs (EMC and Mengo), and we use high-tech recombinant engineering, reverse genetics and cell-free protein synthesis techniques to unravel the virus life cycle, step by step. 

The major focus of my laboratory is Prostate, Breast and Skin Cancers. Our research pursues three major lines of investigation; i) Mechanism of cancer development and identification of molecular targets for intervention, ii) Chemoprevention of cancer by plant-based agents, and iii) Complementary and Alternative Approaches for the prevention and treatment of skin cancer. We are studying the molecular mechanism(s) of ultraviolet (UV) radiation-mediated cutaneous damages. We also study the potential of resveratrol (trans-3, 5, 4-trihydroxystilbene), an antioxidant found in grapes, red wines and a variety of nuts and berries, for the prevention/treatment of skin cancer. Our work has shown the involvement of i) cki-cyclin-cdk network, and MAPK-pathway, ii) Survivin signaling in photoprotective effects of resveratrol in vivo. We have shown that resveratrol prevents UVB exposure-mediated skin carcinogenesis in SKH-1 hairless mice.

My laboratory also studies the chemopreventive/therapeutic potential of melatonin, a pineal hormone and a strong antioxidant, in the management of cancer. Another aim is to define the role of the Polo-Like Kinase (PLK) family of mitotic kinases in the development of prostate and skin cancers. Further, we are investigating the role of sirtuin (SIRT) proteins that belong to the family of type III histone deacetylases (HDAC’s), in cancer development. This research has indicated that SIRT proteins are overexpressed in prostate cancer and may possibly serve as a novel target for the development of therapeutics as well as potential biomarkers for prostate cancer.  

The focus of our research is on understanding the molecular mechanisms governing the activity of estrogen receptor (ER), a member of the nuclear receptor transcription factor family that is critical in normal reproduction and is implicated in the pathogenesis of breast cancer. ER is an intracellular receptor that when activated by estrogen and other estrogen-like compounds, binds directly to DNA and activates or represses gene transcription. It serves as an important model for the understanding of basic mechanisms of transcription, as well as the regulatory pathways that control the cellular responses to steroid hormones. Currently, we are pursuing projects that address the role of post-translational regulation in the control of ERa protein activity, with emphasis on proteasome-mediated proteolysis.

Epithelial tumors are the most frequent form of human cancer. The process(es) by which human epithelial cells acquire aberrant growth and differentiation properties are fundamental to our understanding of the biology of epithelial cancers. Research in my laboratory is currently addressing questions regarding:

•The role of cell-substratum interaction in gene expression and terminal differentiation of epithelial cells (Sadek and Allen-Hoffmann, 1994),
•Use of keratinocytes to detect genotoxic damage caused by environmental agents (Allen-Hoffmann et al., 1993), and
•Changes in production of extracellular matrix glycoproteins that may contribute to progression of epithelial tumors to malignancy (Sheibani et al., 1991).