Apatinib inhibits the growth of small cell lung cancer via a mechanism mediated by VEGF, PI3K/Akt and Ki‐67/CD31

This study aimed to investigate the anti‐tumour effect of apatinib on extensive‐stage small cell lung cancer (SCLC) and elucidate the associated mechanisms. NCI‐H345 cells were selected as model cells because of high expression of vascular endothelial growth factor (VEGF), VEGF receptor 2 (VEGFR2) and phosphorylated‐VEGFR2 (pVEGFR2). Cells were exposed to recombinant human VEGF (rhVEGF) and apatinib. Cells were then divided into eight groups, namely, control, rhVEGF, apatinib, rhVEGF+apatinib, serum‐free medium (SM), SM+rhVEGF, SM+apatinib and SM+rhVEGF+apatinib. In comparison with the control group, cell proliferation in vitro in apatinib, SM, SM+apatinib and SM+rhVEGF+apatinib groups was inhibited, particularly in SM+apatinib group. The effect of apatinib on tumour growth in vivo was investigated using a mouse xenograft tumour model. In comparison with the control group, tumour sizes were reduced in apatinib‐treated group on days 34 and 37. Immunohistochemical and immunofluorescence staining revealed that VEGF, pVEGFR2, PI3K, AKT, p‐ERK1/2, Ki‐67 and CD31 in the tumour cells of apatinib‐treated group were downregulated compared with control group. Haematoxylin and eosin staining revealed that apatinib promoted the necrosis of SCLC cells in vivo. In conclusion, apatinib inhibited the growth of SCLC cells by downregulating the expression of VEGF, pVEGFR2, p‐PI3K, p‐AKT, p‐ERK1/2, Ki‐67 and CD31.