Apoptosis induction in human lung and colon cancer cells via impeding VEGF signaling pathways

There is ample evidence to suggest that vascular endothelial growth factor (VEGF) is a potent mitogen factor in vasculogenesis and angiogenesis and that blockade of VEGF-mediated signals can also prevent tumor growth via enforcing cell apoptosis. In the current study, we assessed the suppressing effect of VGB4, a VEGF antagonist peptide with the binding ability to both VEGF receptor1 and VEGF receptor2, on VEGF-induced proliferation and migration of the human lung adenocarcinoma cell line A549 and the human colon adenocarcinoma cell line HT29 using MTT assay, colony formation assay, and Scratch-wound assay. To evaluate the apoptotic inductive effect of VGB4 on A549 and HT29 cells, apoptosis analysis was carried out by flow cytometry and TUNEL assay. Likewise, p53 and PTEN expression level was examined by immunofluorescence microscopy. In addition, the level of proteins involved in VEGF signaling pathways related to apoptosis was investigated using western blot analysis. Our results indicated that VGB4 markedly inhibited VEGF-induced proliferation and migration, and induced apoptosis of A549 and HT29 cells dose dependently. Encouragingly, significant downregulation of B-cell lymphoma 2 (Bcl2), X-linked inhibitor of apoptosis, Procaspase9, and procaspase3, as well as upregulation of PTEN and P53 tumor suppressors, BCL2 associated X, Cytochrome c, cleaved caspase9, and cleaved caspase3 in VGB4-treated A549 and HT29 cells, further confirmed the profound inductive influence of VGB4 on apoptotic pathways. These findings along with the results from our previous studies show that VGB4 may be considerable for cancer therapy.