A Rac-specific competitive inhibitor of guanine nucleotide binding reduces metastasis in triple-negative breast cancer.

The dysregulation of RAC1 activity is associated with neoplastic transformation, metastasis, and poor prognosis in several cancers. Here, we discover in silico a series of RAC1 inhibitors. The most potent of them, A41, specifically inhibits RAC1 with an original mechanism of action. We characterize A41 as a reversible inhibitor that competes with guanine nucleotide binding specifically on RAC proteins. A41 efficiently blocks RAC1 activity and RAC1-dependent cell functions including cell adhesion and migration. Chronic administration of A41 exhibits anti-metastatic effects in mouse models of triple-negative breast cancer, leading to an increase in the survival rate. Our findings suggest that this molecule, A41, could be a promising and powerful therapeutic agent for limiting invasive cancers in patients.