A Novel Small Molecule Inhibitor of FAK and IGF-1R Protein Interactions Decreases Growth of Human Esophageal Carcinoma

Introduction: Esophageal cancer remains an aggressive disease with poor survival rates. FAK and IGF-1R are two important tyrosine kinases important for cell survival signaling and found to be upregulated in esophageal cancer. Our hypothesis is that a novel small molecule compound that disrupts FAK and IGF-1R protein-protein interactions (PPIs) would decrease the growth of human esophageal cancer. Methods: The compound INT2-31 (NSC344553) was identified from a virtual high throughput screen to bind to FAK and disrupt PPIs. The in vitro effects of this compound, +/- 5-FU chemotherapy, on cell signaling, viability and apoptosis in human esophageal cancer cells (KYSE 70, 140) and a direct esophageal cancer xenograft was evaluated. Results: INT2-31 caused a disruption of PPIs between FAK and IGF-1R starting at a concentration of 1μM. It also caused a dose dependent inhibition of cell viability and induction of apoptosis at low micromolar doses. These effects were associated with decreased AKT and ERK1/ERK2 phosphorylation. INT2-31 treatment, when administered via IP injection, at 50mg/kg, resulted in an in vivo decrease in tumor growth in a direct xenograft. Furthermore, treatment with 5-FU chemotherapy combined with INT2-31 resulted in a synergistic increase in apoptosis and decrease in tumor growth compared to 5-FU or INT2-31 alone. Conclusions: A novel compound that disrupts the PPIs of FAK and IGF-1R results in decreased tumor proliferation and increased apoptosis. These effects appear to be mediated through downregulation of p-AKT and p-ERK. This compound deserves further study as a novel treatment strategy in patients with esophageal cancer.