Current Research Interests
The 90 kDa heat shock proteins (Hsp90) are molecular chaperones that are required for the refolding of denatured proteins and the maturation of nascent polypeptides into their biologically active, three-dimensional structures. In fact, numerous proteins represented in all ten hallmarks of cancer are dependent upon Hsp90 for their conformational maturation. Hsp90 inhibition provides a combinatorial attack on multiple pathways that are responsible for malignant cell growth and proliferation. Consequently, Hsp90 has emerged as a promising target for the development of cancer chemotherapeutics.
Hsp90 contains two ATP binding sites, and in order to fold nascent polypeptides into biologically active proteins, Hsp90 catalyzes the hydrolysis of ATP. ATP hydrolysis provides the Hsp90 protein folding machinery the requisite energy for folding "client" proteins into their correct three-dimensional conformations. Disruption of this folding process results in the destabilization of Hsp90 "client" protein complexes, which leads to ubiquitinylation and proteasome-mediated degradation of the protein substrate.
The N-terminal ATP binding site is inhibited by the natural products geldanamycin (GDA) and radicicol (RDC). Numerous (~20) analogs of these natural products and the nucleotide have undergone clinical evaluation for the potential treatment of cancer. Unfortunately, the vast majority of these molecules have failed. The current hypothesis is that on-target toxicities are produced when all four Hsp90 isoforms are targeted simultaneously. Therefore, we are working towards the development of isoform selective Hsp90 inhibitors and have produced the first Grp94-selective inhibitor and most recently, the first Hsp90β-selective inhibitor. Both of these molecules manifest biological activities that are useful for the treatment of disease.
The C-terminal ATP binding site was identified by one of our collaborators, Len Neckers (National Cancer Institute), who demonstrated that the coumarin antibiotics, including novobiocin, inhibit the C-terminal ATP binding site and lead to the degradation of Hsp90 client proteins similarly to N-terminal inhibitors. Unfortunately, novobiocin's activity is not sufficient for further clinical evaluation and thus represents an opportunity to develop more efficacious Hsp90 inhibitors. We have developed the most potent C-terminal inhibitors of Hsp90 yet discovered and have demonstrated the Hsp90 inhibitors possess potent neuroprotective activities against Alzheimer's, Parkinson's, diabetic peripheral neuropathy, and Multiple Sclerosis. Through optimization of the scaffold, we have produced a neuroprotective agent that is currently in Phase I human clinical trials for neuropathy.
Hsp90 contains two ATP binding sites, and in order to fold nascent polypeptides into biologically active proteins, Hsp90 catalyzes the hydrolysis of ATP. ATP hydrolysis provides the Hsp90 protein folding machinery the requisite energy for folding "client" proteins into their correct three-dimensional conformations. Disruption of this folding process results in the destabilization of Hsp90 "client" protein complexes, which leads to ubiquitinylation and proteasome-mediated degradation of the protein substrate.
The N-terminal ATP binding site is inhibited by the natural products geldanamycin (GDA) and radicicol (RDC). Numerous (~20) analogs of these natural products and the nucleotide have undergone clinical evaluation for the potential treatment of cancer. Unfortunately, the vast majority of these molecules have failed. The current hypothesis is that on-target toxicities are produced when all four Hsp90 isoforms are targeted simultaneously. Therefore, we are working towards the development of isoform selective Hsp90 inhibitors and have produced the first Grp94-selective inhibitor and most recently, the first Hsp90β-selective inhibitor. Both of these molecules manifest biological activities that are useful for the treatment of disease.
The C-terminal ATP binding site was identified by one of our collaborators, Len Neckers (National Cancer Institute), who demonstrated that the coumarin antibiotics, including novobiocin, inhibit the C-terminal ATP binding site and lead to the degradation of Hsp90 client proteins similarly to N-terminal inhibitors. Unfortunately, novobiocin's activity is not sufficient for further clinical evaluation and thus represents an opportunity to develop more efficacious Hsp90 inhibitors. We have developed the most potent C-terminal inhibitors of Hsp90 yet discovered and have demonstrated the Hsp90 inhibitors possess potent neuroprotective activities against Alzheimer's, Parkinson's, diabetic peripheral neuropathy, and Multiple Sclerosis. Through optimization of the scaffold, we have produced a neuroprotective agent that is currently in Phase I human clinical trials for neuropathy.