The C-terminal region of the focal adhesion kinase F1 domain binds Akt1 and inhibits pressure-induced cell adhesion

Abstract

Increased extracellular pressure or shear stress activate a complex signal pathway that stimulates integrin binding affinity and potentiates metastatic cell adhesion. Inhibiting either focal adhesion kinase (FAK) and Akt1 can block this pathway, but risks interfering with the diverse other functions of each kinase. However, the mechanotransduced signal pathway involves a novel Akt1-FAK interaction not required for most FAK or Akt1 function, so modeling and blocking this interaction seems a desirable target. Building upon previous work suggesting that FAK-Akt1 binding is mediated by the FAK F1 lobe, we demonstrated that independently expressing the F1 domain in human Caco-2 or murine CT-26 colon cancer cells by transient or stable inducible plasmid expression respectively prevents the stimulation of cancer cell adhesion by increased extracellular pressure. Serial further truncation of the FAK F1 lobe identified shorter regions capable of pulling down Akt1 on a glutathione S-transferase (GST) - conjugated column. Ultimately, we identified a 33 residue segment (residues 94-126) at the C-terminal of the F1 lobe as sufficient to pull down Akt1. These findings raise the possibility of developing a treatment modality around the disruption of the FAK-Akt1 interaction using peptides modeled from FAK.