cular Endothelial Growth Factor Receptor-1 Signaling motes Mobilization of Macrophage Lineage Cells from R e Marrow and Stimulates Solid Tumor Growth

nloaded cular endothelial growth factor and its receptors, including Flt-1 and Flk-1, are involved in angiogenesis physiologic and pathologic conditions. Recently, Flt-1–expressing cells were reported to contribute to racranial growth of glioma cells. However, the role of Flt-1 signaling in solid tumor growth in s.c. tissue t been elucidated. To investigate how Flt-1 signaling is involved in the proliferation of solid tumors, we ted tumor cells into wild-type (Wt) and Flt-1 tyrosine kinase (TK)–deficient (Flt-1 TK) mice. Growth L and B16 but not Lewis lung carcinoma cell in s.c. tissue was significantly decreased in Flt-1 TK Angiogenesis in HSML and B16 tumors was remarkably reduced in Flt-1 TK mice. Moreover, the inon of macrophage lineage cells into HSML and B16 tumors was clearly suppressed in Flt-1 TK mice. te marker cells were also reduced in Flt-1 TK mice. However, in the border area of tumor, angiogend the infiltration of macrophage lineage cell were basically similar between Wt and Flt-1 TK mice. In arrow (BM) transplantation experiments, tumor angiogenesis, infiltration of macrophage lineage cells, mor growth were significantly suppressed in Wt/Flt-1 TK mice implanted with Flt-1 TK BM cells red with those implanted with Wt BM cells. We conclude that Flt-1 signaling is involved in the function compa of BM-derived cell, such as the migration of macrophages into cancerous tissues, and significantly contributes to angiogenesis and tumor progression. Cancer Res; 70(20); 8211–21. ©2010 AACR.