Two kinds of anti c MET specific siRNAs were transfected into EpS cells, which resulted in significant inhibition of c MET and p MET expression. The silencing of c MET expression decreased selleck chemicals Regorafenib the proliferation and colony formation of EpS cells. These findings suggested that the HGF/c MET signaling pathway affected EpS cell growth. INC280 inhibits EpS cell growth, but the dependency of VAESBJ cells on c MET signaling differs from that of Asra EPS cells A recently developed c MET inhibitor, INC280, has been shown to inhibit c MET dependent cell motility, proliferation, and invasion in several cancer cell lines in vitro and in vivo. First, we tested the antitumor effects of INC280 on the growth of Asra EPS and VAESBJ cells in vitro.

Proliferation of Asra EPS and VAESBJ cells was suppressed in a dose dependent manner by INC280 treatment, albeit with continuous proliferation of SYO 1 or HDF cells. However, its anti proliferative effects were much higher on Asra EPS cells than on VAESBJ cells. Flow cytometry analyses showed that INC280 induced a greater increase in G0/G1 phase population in Asra EPS cells than in VAESBJ cells. Cleavage of caspase 3 was induced after INC280 exposure in a dose dependent manner in Asra EPS cells, but its induction was hardly observed in VAESBJ cells. These data indicated that Asra EPS cells were more sensitive to INC280 than VAESBJ cells because its effects inducing G0/G1 cell cycle arrest and apoptosis were higher on Asra EPS cells than on VAESBJ cells. Second, we examined the efficacy of INC280 on the c MET downstream pathways in Asra EPS and VAESBJ cells.

The PI3K/AKT/mTOR and mitogen activated protein kinase /ERK signaling pathways are downstream of c MET signaling. INC280 strikingly inhibited phosphorylation of c MET and its downstream molecules such as AKT and ERK in Asra EPS cells but did not decrease phosphorylation of AKT or ERK in HDF cells. These results suggested that Asra EPS cells were highly addicted to c MET signaling. By contrast, INC280 remarkably blocked phosphorylation of c MET and ERK in VAESBJ cells, but AKT phosphorylation was incompletely suppressed. These data indicated that compared with Asra EPS cells, VAESBJ cells were less dependent on c MET signaling in vitro, which resulted in sustained AKT activation after INC280 treatment in VAESBJ cells. We then evaluated the antitumor effects of INC280 on progression of VAESBJ xenograft tumors in mice.

An INC280 dose of 10 mg/kg given orally once a day was selected on the basis of the previous observation that this therapeutic dose resulted in inhibition of Dacomitinib c MET phosphorylation in vivo. MG132 The administration of INC280 delayed VAESBJ xenograft tumor growth com pared with that of the vehicle control, whereas INC280 treated tumors grew gradually. Western blot analyses demonstrated a decrease in expression of phosphorylated c MET in INC280 treated tumors.