OBJECTIVETo investigate the relationship between vascular endothelial growth factor D (VEGF-D) and metastasis of lymphatic vessel in gastric carcinoma.

METHODSThe human VEGF-D cDNA was amplified from total RNA isolated from human normal gastric tissue, then it was inserted into T-A clone plasmid and subcloned into pEGFP eukaryotic expression vector. After the full-length sequence expected was confirmed by enzymatic digestion and sequencing,the human gastric carcinoma cell line SGC7901, which expressed a low level of VEGF-D, was transfected with the pEGFP/VEGF-D expression vector. Stable SGC7901 clones with high expression of VEGF-D were selected in vitro with G418, which were then combined and subcutaneously injected into nude mice to observe the density and morphology of lymphatic vessel. The outcomes were later compared with those of SGC7901 cells transfected with null vector(pEGFP) by immunostaining with a specific antibody LYVE-1.

RESULTSThe average weight of tumors in the pEGFP group (1.13+/-0.40) g at day 35, was significantly lower than that in the pEGFP/VEGF-D group (2.24+/-0.82)g (P<0.05). The lymphatic vessel density (LVD) in the pEGFP group (2.89+/-1.32) was significantly lower than that in the pEGFP/VEGF-D group (5.74+/-1.30)(P<0.01). There were dilated functional lymphatic vessels around the tumor margin.

CONCLUSIONVEGF-D may promote the growth and metastasis of tumor in gastric carcinoma by increasing the growth of lymphatic vessels.