Radiosensitizing effect of c-Met kinase inhibitor BPI-9016M in esophageal squamous cell carcinoma cells in vitro and in vivo

BACKGROUND: c-Met is the receptor of hepatocyte growth factor (HGF) which plays a key role in inhibiting apoptosis. BPI-9016M is a small-molecule c-Met inhibitor that can promote apoptosis and enhance the cytotoxicity of various DNA-damaging agents. Here, we evaluated the radiosensitizing potential of BPI-9016M in Eca109 human esophageal squamous cell carcinoma (ESCC) cells in vitro and in vivo. METHODS: Cell Counting Kit-8 (CCK-8) assay was used to measure cell viability. Clonogenic survival assay and a murine tumor xenograft in male nude mice were used to evaluate the radiosensitizing effect of BPI-9016M. Apoptosis was determined by the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining and flow cytometry experiment. Apoptosis-related proteins were detected by western blot. By evaluating the activation of the ATR-Chk1/ATM-Chk2 pathway to detect radiation-induced DNA double-strand break and homologous recombination repair. BPI-9016M induced a radiosensitizing effect in Eca109 cells and reduced the survival rate of clone formation in vitro. RESULTS: The combination of BPI-9016M with irradiation (IR) significantly delayed the growth of ESCC tumor xenografts than treatment alone (P<0.05). The radiosensitizing effects of BPI-9016M were due to increased apoptosis, such as the up-regulation of cleaved-caspase 3 and 9, down-regulation of mutant P53 and Bcl-2, the decreased of phosphorylation of ATR and ATM, and the inhibition of γ-H2AX accumulation in vitro and in vivo. CONCLUSIONS: These findings indicated that BPI-9016M exerts a radiosensitizing effect and enhances apoptosis by inhibiting homologous recombination DNA repair in irradiated ESCC cells.