Kinase Imaging

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This project brings together a new team of established scientists to explore novel chemistries that ultimately will enable imaging of the kinases involved in signaling transduction in humans. The chemistries to be explored include a) systematic natural product derivatization to optimize delivery pharmacokinetics, b) peptide library approaches and c) the design of cell membrane permeable peptide substrates (olefin stapling, peptide chimera). These chemistries have been selected because each has been shown to yield membrane permeable small molecules that react with intracellular targets in a highly specific manner. We will focus on two targets, the lipid kinase PI3K (phosphoinositide 3-kinase) and the protein kinase AKT (PKB). The PI3K pathway is up-regulated in up to 90% of human cancers leading to enhanced cell growth, cell survival and cell migration. Importantly, the PI3K pathway is a primary, non-redundant controlling mechanism for many cancer related processes such as angiogenesis, apoptosis, cell survival, cell migration, and cell proliferation. By controlling this critical signaling center, it can serve as a read-out for many redundant upstream extracellular and downstream intracellular signaling targets, such as VEGFR (Avastin), her2/neu (Erbitux), or PDGFR (Gleevec). The specific aims are as follows: 1) Develop and validate imaging agents for PI3K based on the viridin family of alkaloids that are membrane permeable and which are trapped inside cells due their covalent modification of a lysine in ATP site of PI3K, 2) develop and validate imaging agents for AKT based on peptides or peptidomimetics that are membrane permeable, which will be phosphorylated by this kinase and trapped intracellulary due to a change in charge and 3) validate the above imaging agents in mouse models of pancreatic ductal adenocarcinoma (PDAC). The specific goals of these experiments are to a) validate imaging measurements and correlate them to gold standards, b) perform therapeutic trials of PDAC treatments to test the utility of the newly developed imaging agents as biomarkers and c) apply them to ask questions about PI3K/AKT biology in PDAC.