Radiosensitizing effect of ARQ197, a small-molecule tyrosine kinase inhibitor of c-Met, on lung cancer cell line H1299

Abstract

Objective To evaluate the radiosensitizing effect and action mechanism of a tyrosine kinase inhibitor, ARQ197, on lung cancer cell line H1299. Methods H1299 cells were treated with different concentrations of recombinant human hepatocyte growth factor (HGF) and ARQ197, respectively. Colony formation assay was used to investigate the proliferation of H1299 cells, and the optimal concentrations of HGF and ARQ197 were figured out for the radiosensitivity study. H1299 cells were divided into control, HGF-treated, ARQ197-treated, and HGF+ ARQ197-treated groups, and the differences between those groups were evaluated. The impacts of HGF, radiation alone, or HGF+ ARQ197 on the expression and activation of c-Met and the downstream Akt and Erk1/2 were determined by Western blot. Results The colony formation rate of H1299 cells increased with increasing HGF concentration, and decreased with increasing ARQ197 concentration. Using the linear-quadratic model, the cell survival curve showed that the radiation dose enhancement ratios for H1299 cells treated with HGF, HGF+ ARQ197, and ARQ197 were 0.85, 1.20, and 1.27, respectively, when the surviving fraction was 0.1. The expression of pc-Met, p-Akt, and p-Erk1/2 proteins increased in H1299 cells after HGF stimulation. In HGF+ ARQ197-treated cells, the expression of pc-Met, p-Akt, and p-Erk1/2 proteins decreased with increasing ARQ197 concentration. After 2 Gy irradiation, the expression of pc-Met, p-Akt, and p-Erk1/2 proteins increased in HGF-treated cells but substantially decreased in HGF+ ARQ197-treated cells, while there were no significant changes in the expression of total c-Met, Akt, and Erk1/2 proteins. Conclusions ARQ197 has a substantial radiosensitizing effect on lung cancer cell line H1299 in vitro by inhibiting HGF/c-Met and activation of downstream signaling pathways. Key words: H1299 cell line; Radiosensitivity; c-Met tyrosine kinase inhibitor