Epidermal growth factor-like domain 7 regulates breast cancer cell proliferation and vascular endothelial growth factor expression via the p38MAPK signaling pathway.

OBJECTIVE

We aimed to investigate the effects of epidermal growth factor-like domain 7 (EGFL7) on breast cancer cell proliferation and angiogenesis and its association with the p38 mitogen-activated protein kinase (p38MAPK) signaling pathway.

METHODS

The vectors for stable overexpression of EGFL7 and the vectors for EGFL7 knockout were constructed. The breast cancer cell line MDA-MB-231 was selected for this study and the cells were divided into four groups: the control group, the empty vector group (transfected with an empty vector), the EGFL7 overexpression group (transfected with the EGFL7 overexpression vector), and the EGFL7 knockout group (transfected with the EGFL7 knockout vector). After 72 h of transfection, the mRNA and protein levels of EGFL7 in the cells were detected by RT-PCR and Western blot, respectively. The cell proliferation rates at 12 h, 24 h, 48 h and 72 h of culture in each group were detected using the MTT method. An tumor angiogenesis model of tumor-endothelial cells co-culture system was established and the angiogenesis ability at 12 h, 24 h, 48 h and 72 h of culture were compared among the groups using an angiogenesis assay. The cells in the EGFL7 overexpression group were further divided into three groups and were treated with p38MAPK inhibitor SB203580 at a dose of 0 μmol/L, 5 μmol/L, and 10 μmol/L, respectively. Afterward, the cells were co-cultured with endothelial cells for 48 h. Western blot was performed to detect the protein levels of vascular endothelial growth factor (VEGF), p38MAPK, and p-p38MAPK.

RESULTS

Compared with the control group, the EGFL7 mRNA level was higher in the EGFL7 overexpression group and lower in the EGFL7 knockout group (both P<0.05). Compared with the control group at 12 h, 24 h, 48 h, and 72 h of culture, the cell proliferation rates were lower in the EGFL knockout group and higher in the EGFL overexpression group, respectively (all P<0.05). Moreover, compared with the control group at these time points, the number of vascular sprouts and the protein levels of VEGF, p38MAPK, and p-p38MAPK were lower in the EGFL7 knockout group and higher in the EGFL7 overexpression group, respectively (all P<0.05). After the cells overexpressing EGFL7 were treated with SB203580, the level of p-p38MAPK was deceased, and the protein expression level of VEGF was inversely related with the SB203580 concentration (F=44.24, P<0.01).

CONCLUSION

EGFL7 can promote the proliferation of breast cancer cells and angiogenesis, and the mechanism may be associated with the activation of p38MAPK signaling pathway and promotion of VEGF expression.