Abstract 1295: Inhibition of platelet derived growth factor receptor tyrosine kinase reduces lymphangiogenesis of human gastrointestinal cancer

Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Objective: Vascular endothelial growth factor (VEGF)-C/D induces lymphangiogenesis by activating VEGF receptor (VEGFR)-3, which is expressed on lymphatic endothelial cells. Platelet derived growth factor receptor (PDGF-R) has also been detected on lymphatic endothelial cells and PDGF-BB acts as a lymphangiogenic factor in murine fibrosarcoma. We have previously reported that PDGF-R is expressed by lymphatic endothelial cells in human gastric cancer and its expression levels in tumor tissue correlate with lymph node metastasis. In this study, we examined whether inhibition of PDGF-R tyrosine kinase signaling by imatinib affects lymphangiogenesis and lymph node metastasis of human gastrointestinal cancer cells growing in the orthotopic site of nude mice. Methods: TMK-1 human gastric cancer cells or KM12SM human colon cancer cells were injected into the orthotopic site of nude mice. Groups of mice (n=10) received saline (control), imatinib, the cancer chemotherapeutic irinotecan, or a combination of imatinib and irinotecan. The lymphatic vessels were then stained with antibodies against Lyve 1. Results: Lymphatic endothelial cells as well as activated fibroblasts in the tumor stroma express PDGF-R. Four weeks of treatment with imatinib and irinotecan significantly inhibited lymph node metastasis (relative to control or single-agent therapy). Imatinib alone or in combination with irinotecan significantly decreased number and area of lymphatic vessels in the tumor stroma. Conclusion: Administration of a PDGF-R tyrosine kinase inhibitor in combination with irinotecan inhibits the lymph node metastasis of orthotopically implanted gastrointestinal cancer cells in nude mice by blocking PDGF-R signaling in tumor-associated lymphatic endothelial cells. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1295.