Abstract A13: Discovery of selective inhibitors of the kinase and metastatic activities of the activated Cdc42-associated kinase (ACK1)

Activated Cdc42-associated kinase (ACK1) is a non-receptor tyrosine kinase and an effector protein of Cdc42. Previous reports have demonstrated that ACK1 is a critical factor in the cellular transformation of a number of cancer cell lines. ACK1 also contributes to cellular motility, and overexpression in certain cell lines results in enhanced motility. The significance of tyrosine kinase proteins such as ACK1 in cancer-related signaling pathways, and the implications of metastasis in the prognosis of cancer patients, point to the importance of the discovery of a potent yet selective inhibitor for this protein. As a result, we are engaged in a study focused on applying computational approaches to identify novel inhibitor molecules of ACK that will also hamper its ability to promote motility of cancer cells. We employed customized in-house computational tools to retrieve approximately 50 small-molecule hits from our chemical databases that may bind with high affinity to the ACK1 ATP binding pocket. These hits were further screened for drug-like properties (Lipinski9s Rule of 5) and rescored using GOLD docking to the ACK1 crystal structure (PDB3EQR). After rescoring, the top 25 hits were then tested for in vitro cytotoxicity in a variety of cancer cell lines. Compounds were specifically examined for their impact on the kinase activity of purified ACK1 and for their ability to modulate its metastatic properties in wound healing and transwell migration assays. Our screening has revealed that several compounds have the ability to inhibit the in vitro kinase activity of ACK1 and also inhibit the in vitro growth of cancer cells. Ongoing immunofluorescence, cellular transformation, and cellular motility studies suggest that the selected compounds may modulate the effect of ACK1 on the motility of cancer cells. We are actively proceeding with specific structural modifications of our initial inhibitor compounds in order to find molecules which possess increased cytotoxicity to cancer cells and improved specificity for the inhibition of ACK. Citation Information: Clin Cancer Res 2010;16(14 Suppl):A13.