Functional and therapeutic relevance of hepatocyte growth factor/c‐MET signaling in synovial sarcoma

Synovial sarcoma (SS) is an aggressive soft tissue sarcoma with a poor prognosis and, thus, novel therapeutic strategies for SS are urgently required. In the present study, we investigated the functional and therapeutic relevance of hepatocyte growth factor (HGF)/c-MET signaling in SS. Both HGF and c-MET were highly expressed in Yamato-SS cells, resulting in activation of c-MET and its downstream AKT and extracellular signal-regulated kinase signaling pathways, whereas c-MET was expressed but not activated in SYO-1 or HS-SY-II cells. c-MET-activated Yamato-SS cells showed higher anchorage-independent growth ability and less sensitivity to chemotherapeutic agents than did c-MET-inactivated SYO-1 or HS-SY-II cells. INC280, a selective c-MET inhibitor, inhibited growth of Yamato-SS cells both in vitro and in vivo but not that of SYO-1 or HS-SY-II cells. INC280 induced cell cycle arrest and apoptosis, and blocked phosphorylation of c-MET and its downstream effectors in Yamato-SS cells. Co-expression of HGF and c-MET in SS clinical samples correlated with a poor prognosis in patients with SS. Taken together, activation of HGF/c-MET signaling in an autocrine fashion leads to an aggressive phenotype in SS and targeting of this signaling exerts superior antitumor effects on c-MET-activated SS. HGF/c-MET expression status is a potential biomarker for identification of SS patients with a worse prognosis who can benefit from c-MET inhibitors.