Suppression of VEGFR‐3 signaling inhibits lymph node metastasis in gastric cancer

In gastric cancer, lymph node metastasis is one of the major prognostic factors and forms the basis for surgical removal of local lymph nodes. Recently, several studies have demonstrated that overexpression of lymphangiogenic growth factor VEGF‐C or VEGF‐D induces tumor lymphangiogenesis and promotes lymphatic metastasis in mouse tumor models. We examined whether these processes could be inhibited in naturally metastatic tumors by blocking of their cognate receptor VEGFR‐3 signaling pathway. Using a mouse orthotopic gastric cancer model which has a high frequency of lymph node metastasis, we estimated lymphatic vessels in gastric cancers by immunostaining for VEGFR‐3 and other specific lymphatic markers, LYVE‐1 and prox‐1. Then we systemically administered anti‐VEGFR‐3 blocking antibodies. This treatment resulted in the inhibition of regional lymph node metastasis and reduction of lymphatic vessel density in the primary tumors. In addition, increased density of LYVE‐1‐positive lymphatic vessels of primary tumors was closely correlated with lymph node metastasis in human samples of gastric cancer. Antilymphangiogenesis by inhibiting VEGFR‐3 signaling could provide a potential strategy for the prevention of lymph node metastasis in gastric cancer.