Identification of potential small-molecule protein-protein inhibitors of cancer metastasis by 3D epitope-based computational screening.

In cancer cells exposed to extracellular pressure or shear stress, AKT1-FAK interaction drives focal adhesion kinase (FAK) phosphorylation, leading to force-activated cancer cell adhesion and metastasis. Blocking the AKT1-FAK interaction is therefore an attractive target for cancer therapy, avoiding the side effects of global FAK inhibition. Starting with our previous identification of a short FAK peptide that binds AKT1, we identified a series of small-molecule inhibitor candidates using a novel approach for inhibiting protein-protein interactions. Using a 3D structural fragment of the FAK peptide as the query, millions of drug-like, commercially available molecules were screened to identify a subset mimicking the volume and chemistry of the FAK fragment to test for their ability to block pressure-sensitive FAK phosphorylation by AKT1. Two compounds reduced the stimulation of FAK phosphorylation in response to extracellular pressure in human SW620 colon cancer cells without affecting basal FAK phosphorylation. Thus, using a 3D protein interaction epitope as a novel query for ligand-based virtual screening can successfully identify small-molecules that show promise in modulating cancer cell adhesion and metastasis.