University of Virginia Health System

Email Address: jwh6f@virginia.edu

Cancer Research

A recent focus of our laboratory is intervention in SWI/SNF-dependent metabolic pathways for control of tumor cell growth. The SWI2/SNF2 family of DNA-dependent ATPases participates in a number of DNA metabolic processes, including DNA repair, chromatin remodeling, recombination and transcription. Individual members of this family of proteins have been demonstrated to interact with and regulate a limited set of transcription factors including steroid receptors (estrogen receptor, androgen receptor, etc.), p53, C-MYC, the retinoblastoma protein and BRCA1. Many of these factors have been investigated for their role in the development and/or progression of breast cancer or prostate cancer, although the steroid receptor has been the primary target for chemotherapy. We propose that an alternative target might be the underlying distinctive feature of the SWI2/SNF2 proteins, which is a molecular motor domain comprised of an adenosinetriphosphatase (ATPase) catalytic site functionally coupled to a DNA binding site. The latter site effects DNA-dependent ATP hydrolysis when occupied and the peptide elements comprising this domain play an important role in the allosteric modulation of ATP hydrolysis. We observe that a family of inhibitors called phosphoaminoglycosides can alter the function of this core. We have found them to inhibit the SWI2/SNF2 molecular motor, inhibit cell growth and exert selectivity with respect to prostate cancer cell type, which is consistent with the proposed role of SWI2/SNF2 family members regulating androgen receptor function. Regulation of the SWI2/SNF2 family members is a novel and important finding since these proteins regulate a limited number of transcription factors that are intimately involved with cell growth and differentiation. We are exploring the SWI2/SNF2 proteins as novel targets for therapeutic exploitation with specific interest in control of cell growth by the phosphoaminoglycosides.

Malaria Research - Microbiology, Immunology and Infectious Disease

The advent of drug-resistant strains of bacteria and protozoans is expected to exacerbate the already heavy toll parasitic diseases exact on human life and health. Development of new paradigms for controlling these parasites is important and may come through a basic understanding of DNA metabolic events. Our extensive biochemical analysis of a nuclear enzyme's interactions with DNA has led to the discovery of a mechanism to disrupt ATP-dependent DNA metabolic events. Antibiotic-resistant bacteria are the source of potent, naturally occurring inhibitors of eukaryotic DNA-dependent ATPase activity. These are the first reported inhibitors that are specific for DNA-dependent ATP hydrolysis. The DNA-dependent ATPase domain targeted by these inhibitors is found in proteins that play integral roles in many DNA metabolic processes; including DNA replication, transcription, repair, recombination and histone remodeling. Three inhibitors have been demonstrated to be toxic to protozoans (Plasmodium falciparum (Malaria), Entamoeba histolytica, Leishmania chagasi) but not bacteria. Five additional inhibitors have been prepared and demonstrated to be inhibitory for the nuclear enzyme in vitro. The eight derivatives range widely in potency (50-fold) and are generally more than a thousand-fold more potent than the parent antibiotic. The targeting of specific nuclear enzymes leading to disruption of the protozoan life cycle provides an exciting development in the treatment of protozoan diseases. We are attempting to expand and refine our understanding of DNA metabolic events in protozoans and to evaluate mechanisms that could lead to the death of protozoans. Our studies aim to facilitate the development of DNA-dependent ATPase inhibitor species specific for protozoan growth.