DESCRIPTION (provided by applicant): The overarching goal of this research program is to develop synthetic multivalent frameworks for the discernment and manipulation of biological recognition processes that are important in intercellular interactions. Multivalency plays a critical role in many biological interactions, and the development of synthetic multivalent systems to systematically probe these processes is critical for advancement of the rational development of multivalent therapeutics. Because typical individual receptor/ligand interactions in biology are often weak, augmentation of these interactions using multivalency can enhance functional avidity. Moreover, multivalent interactions can create patterns of ligands that can be used to modulate processes in novel ways, and these architectures of structure cannot be formed by traditional small-molecule therapeutics. The proposed research describes the development of dendrimers as tools to advance the understanding of the requirements for multivalent frameworks that are designed to mediate multivalent cancer cellular recognition processes. Our hypothesis is that carbohydrate functionalized dendrimers can be used to form clusters of galectins and that these galectin/glycodendrimer clusters will effectively arbitrate the intercellular recognition events of cancer cells. We have chosen glycodendrimers as the multivalent frameworks for the proposed studies because of the ease of manipulation of their size (generation) and of their end group functionalization. We have chosen galectins as our target proteins because of their known functions in cancer processes. The three specific aims are as follows. 1) Synthesize new carbohydrate-functionalized dendrimers. 2) Characterize the glycodendrimer/galectin binding interactions. 3) Perform cell based and animal model (C. elegans) assays with glycodendrimers. For specific aim 1, chemoenzymatic syntheses to form N-acetyllactosamine and Thomsen-Friedenriech antigen functionalized dendrimers are proposed. The synthesis of dendrimers bearing peptide substrates for matrix metalloproteases is also proposed. For specific aim 2, characterization of glycodendrimer/galectin aggregates is proposed using fluorescence lifetime waveform, fluorescence anisotropy, size exclusion chromatography-multiangle light scattering, surface plasmon resonance and ELISA experiments. Because of the effect of galectins -1 and -3 on cancer cellular aggregation processes, our goal is to characterize the binding affinity of the glycodendrimer/galectin interactions and the pattern of galectin that is displayed to the cells in the presence of glycodendrimers. For specific aim 3, we will perform angiogenesis and cellular adhesion assays in collaboration with Dr. Avraham Raz of the Karmanos Cancer Institute at Wayne State University. We also propose to perform homotypic cellular aggregation assays, chemotaxis and migration assays, mechanoelastic studies, kinetic studies on release of prodrug mimics, and studies with C. elegans.

Multivalent interactions, which occur when two or more molecular recognition events take place simultaneously between two partners, play a critical role in many biological processes. Diseases with multivalent aspects include AIDS, influenza, Alzheimer's disease, diabetes, and cancer. The proposed research describes the development of glycodendrimers as tools to advance the understanding of the requirements for multivalent frameworks that are designed to mediate multivalent cancer cellular recognition processes. The hypothesis that will be tested in the proposed research is that glycodendrimers will form clusters of galectins (carbohydrate binding proteins) and that these galectin/glycodendrimer clusters will effectively arbitrate intercellular recognition events.