Daniel Kenan, Pathology

All solid tumors require ongoing angiogenesis and vascular remodeling in order to exhibit malignant behaviors such as rapid growth, tissue invasion, and metastasis. Angiogenesis is regulated primarily at the level of the endothelial cell through a complex network of interactions with extracellular matrix components, paracrine and endocrine factors, chemical factors, cell-cell signaling, and mechanical stimuli. Endothelial cell biology is poorly understood in the native environment of tumors due to their scarcity and the difficulty in isolating endothelial cells from tissues. Novel technologies developed in this laboratory are being applied to overcome these difficulties.

The technologies that we employ rely on the ability to generate and screen very large recombinant peptide and antibody libraries using bacteriophage display. These technologies can be applied in both differential and proximity cell-based screens to identify the co-regulatory components of receptor complexes in their native environment on the cell-surface. The following projects are ongoing in the laboratory:

1. Characterization of the endothelial cell Tie1 and Tie2 receptors and co-regulatory proteins. Antibody phage display libraries have provided a wealth of recombinant single chain antibody fragments (scFv) against these receptor tyrosine kinases and their coregulatory proteins on the surface of endothelial cells. We are using these tools to characterize angiopoietin signaling and to develop novel inhibitors and activators of angiogenesis that operate through these receptors.
2. Characterization of the endothelial cell angiostatin receptor, F1FO ATP Synthase. In collaboration with Dr. Salvatore Pizzo, we are developing peptide and antibody mimetics of angiostatin and using these compounds to characterize the mechanism of angiostatin inhibition of endothelial cell surface ATP synthase.
3. Discovery of cell surface markers specific to tumor endothelium. We are employing differential screens of antibody display libraries to identify and characterize novel tumor vascular markers. These biomarkers are being evaluated for both diagnostic and therapeutic applications.
4. Differential gene and protein expression in tissue endothelial cells. In collaboration with Dr. Jack Keene, we are developing ribonucleoprotein tagging technologies that enable the recovery of mRNA species from specific cell types in the context of their native tissue environments. These technologies are being used to characterize differential effects on gene and protein expression in tumor endothelium.
5. Interfacial biomaterials and tissue engineering. In collaboration with Drs. Mark Grinstaff and Laura Niklason, we are engineering peptides and scFv isolated from our combinatorial libraries to develop a novel "interfacial biomaterial" (IFBM) technology platform. These IFBMs join two independent affinity modules that are capable of binding and organizing biological materials (cells, molecules, etc.) onto synthetic materials (plastics, metals, synthetic wafers, etc.). IFBM technologies have widespread applications in tissue engineering, wound healing, and biological devices.