Interleukin-8: A potent promoter of angiogenesis in gastric cancer

Angiogenesis is a critical process in the development of tumor malignancy and occurs at various stages of tumor progression. Interleukin-8 (IL-8) is a pro-angiogenic factor produced by tumor-infiltrating macrophages that has been revealed to facilitate the development of angiogenesis in various cancers. However, whether IL-8 activates angiogenesis in gastric cancer remains unclear. The present study investigated the effect of IL-8 on the migration and canalization capacities of human umbilical vein endothelial cells (HUVECs). In addition, the protein and messenger RNA (mRNA) expression of selected angiogenesis markers, consisting of vascular endothelial growth factor (VEGF)-A, VEGF receptor (VEGFR)-1 and VEGFR-2, were assessed in the HUVECs. The HUVECs were co-cultured with human gastric cancer SGC7901 cells and exposed to various concentrations of IL-8 (0, 0.2, 0.5, 0.8 and 1.0 ng/ml). The migration and canalization abilities of the cells were detected by Transwell chamber and tube formation assays. Protein expression was detected using immunofluorescence and western blot analysis, and mRNA levels were assessed using reverse transcription quantitative polymerase chain reaction. The protein and mRNA levels of VEGF-A, VEGFR-1 and VEGFR-2 were measured in HUVECs cultured for 24 h. IL-8 at concentrations of 0.5, 0.8 and 1.0 ng/ml significantly promoted HUVEC cell migration (P=0.005, P=0.001 and P<0.001, respectively) and tube formation (P=0.039, P=0.003 and P<0.001, respectively). IL-8 at concentrations of 0.2, 0.5, 0.8 and 1.0 ng/ml significantly elevated the protein levels of VEGF-A (P<0.001) and VEGFR-2 (P=0.034, P<0.001, P<0.001 and P<0.001, respectively). IL-8 at concentrations of 0.8 and 1.0 ng/ml significantly elevated the protein levels of VEGF-1 (P=0.037 and P=0.002, respectively). Similarly, IL-8 at concentrations of 0.5, 0.8 and 1.0 ng/ml significantly upregulated the mRNA levels of VEGF-A (P=0.046, P=0.001 and P<0.001, respectively) and VEGFR-1 (P=0.042, P<0.001 and P<0.001, respectively). IL-8 at concentrations of 0.2, 0.5, 0.8 and 1.0 ng/ml significantly upregulated the mRNA levels of VEGFR-2 (P=0.003, P=0.005, P<0.001 and P<0.001, respectively). In conclusion, IL-8 may be a potent promoter of angiogenesis in gastric cancer.