BACKGROUNDIt has been known that vascular endothelial growth factor (VEGF) and its receptor (VEGFR2) play important roles in tumor angiogenesis. The aim of this study is to investigate whether an oral DNA vaccine against VEGFR2 has the inhibition effect on tumor growth and angiogenesis, and explore its mechanism in vivo.

METHODSC57BL/6 mice were respectively given the DNA vaccine encoding VEGFR2 (vaccine group), pcDNA3.1 (plasmid group) and saline (saline group). All the mice were then inoculated with Lewis lung carcinoma 3LL cells. Weight, size and microvessel density (MVD) of transplanted tumors were observed. The levels of CD3+ and CD8+ T cells in peripheral blood of mice were detected by flow cytometry.

RESULTSWeight of transplanted tumors in vaccine group was significantly smaller than those in plasmid and saline groups (P < 0.05), and MVD was significantly lower in vaccine group than that in plasmid and saline groups (P < 0.05). After inoculated with 3LL cells, CD3+ and CD8+ T cell levels of vaccine group were markedly higher than those of plasmid and saline groups (P < 0.05).

CONCLUSIONSThe oral DNA vaccine can significantly inhibit angiogenesis and growth of transplanted tumor in mice. It may act through killing endothelial cells of tumor.