Discovery of Cell-Based Chemical Probes Targeting Aberrant Angiogenesis in the Eye

In his lab, McGowan Institute for Regenerative Medicine affiliated faculty member Partha Roy, PhD (pictured), Associate Professor of Bioengineering, Cell Biology, and Pathology at the University of Pittsburgh, and his team are focused on studying how alteration in profilin (a G-actin binding protein that is important for actin cytoskeletal regulation and many actin-dependent cellular processes) expression and/or function impacts breast cancer metastasis and angiogenesis. In this overall context, they explore novel post-translational modifications of ABPs and how these modifications impact protein function and actin-dependent biological processes.

Aberrant angiogenesis, the unwanted and destructive formation of new blood vessels, is associated with several eye diseases that can cause blindness, such as diabetic retinopathy, wet age-related macular degeneration, and retinopathy of prematurity. Dr. Roy is a co-principal investigator on the proposal which will examine molecules for preventing and investigating aberrant angiogenesis in the eye. This 2-year project was funded by the National Eye Institute. Other co-principal investigators are Donna Huryn, PhD, David Ryan Koes, PhD, and Andrew VanDemark, PhD.

The project summary/abstract follows:

Proliferative diabetic retinopathy, wet age-related macular degeneration, and retinopathy of prematurity are all diseases of the eye that can lead to blindness and are due to abnormal development of retinal or choroid blood vessels. Although intravitreal anti-angiogenic therapies targeting vascular endothelial growth factor signaling are generally effective for these diseases, spontaneous or acquired resistance is a significant problem and points to the need for high-quality cell-based chemical probes for interrogating angiogenic pathways and developing alternative therapies. To address this unmet need, we propose developing high-quality cell-based chemical probes for the profilin1 (Pfn1)-actin protein-protein interaction. Pfn1 is critical for angiogenesis as it plays a vital role in the dynamic remodeling of the actin cytoskeleton in response to angiogenic signals. We have shown in numerous contexts that inhibition or suppression of Pfn1 leads to reduced angiogenesis and have recently demonstrated that inhibiting Pfn1 reduces the formation of new blood vessels in both ex vivo and in vivo models of retinopathy. We have already identified a validated hit compound that inhibits the Pfn1-actin interaction in biochemical and cell-based assays and confirmed its target engagement in cells. To increase the potency of this inhibitor while maintaining drug-like properties, we will employ an iterative optimization process that will be guided by our structural and cheminformatic models and by the structure-activity relationship that will be developed around the key points of variation during each iteration of compound selection, synthesis, and biological testing. Derivatives will be evaluated in a gated assay cascade to determine their binding affinity for Pfn1 and activity in cells. This iterative process aims to identify an inhibitor of the Pfn1-actin interaction with sub-micromolar potency in both biochemical and cellular assays. Compounds that meet well-defined criteria for novelty and potency in our first round of assays will be validated in the second series of assays to confirm target engagement, selectivity, and other functional utilities (e.g., synergy with an anti-VEGF agent and barrier-function modulatory agent). Successful completion of these studies will result in a potent and specific inhibitor of Pfn1-actin for studying the role of Pfn1 in aberrant angiogenesis and may ultimately lead to a clinical candidate for the treatment of eye disease.