Data from Breast Cancer–Derived Bone Metastasis Can Be Effectively Reduced through Specific c-MET Inhibitor Tivantinib (ARQ 197) and shRNA c-MET Knockdown

Abstract

<div>Abstract<p>Breast cancer exhibits a propensity to metastasize to bone, resulting in debilitating skeletal complications associated with significant morbidity and poor prognosis. The cross-talk between metastatic cancer cells and bone is critical to the development and progression of bone metastases. We have shown the involvement of the HGF/c-MET system in tumor–bone interaction contributing to human breast cancer metastasis. Therefore, disruption of HGF/c-MET signaling is a potential targeted approach to treating metastatic bone disease. In this study, we evaluated the effects of c-MET inhibition by both an oral, selective, small-molecule c-MET inhibitor, tivantinib, and a specific short hairpin RNA (shRNA) against c-MET in a mouse model of human breast cancer. Tivantinib exhibited dose-dependent antimetastatic activity <i>in vivo</i>, and the 120 mg/kg dose, proven to be suboptimal in reducing subcutaneous tumor growth, induced significant inhibition of metastatic growth of breast cancer cells in bone and a noteworthy reduction of tumor-induced osteolysis. shRNA-mediated c-MET silencing did not affect <i>in vitro</i> proliferation of bone metastatic cells, but significantly reduced their migration, and this effect was further enhanced by tivantinib. Both observations were confirmed <i>in vivo</i>. Indeed, more pronounced tumor growth suppression with concomitant marked decreases of lytic lesions and prolongation of survival were achieved by dual c-MET inhibition using both tivantinib and RNA interference strategies. Overall, our findings highlighted the effectiveness of c-MET inhibition in delaying the onset and progression of bone metastases and strongly suggest that targeting c-MET may have promising therapeutic value in the treatment of bone metastases from breast cancer. <i>Mol Cancer Ther; 11(1); 214–23. ©2011 AACR</i>.</p></div>