Antiangiogenic Therapy Impedes Infiltration by CD4+ and CD8+ Cells Into an Early Colon Tumor

BACKGROUND: While the majority of angiogenesis studies have focused on the late stages of cancer, the emergence of neovascularization in colon tumorigenesis has been observed an earlier stage than expected. Recent reports implied that early angiogenesis might be a defense mechanism to stimulate the natural clearance of microadenomas during colon tumorigenesis. However, little is known about how early angiogenesis affects the natural clearance of tumors. METHODS: Spontaneous colon tumors were developed in adenomatous polyposis coli conditional knockout mice with Cre recombinase adenovirus administration. Vascular endothelial growth factor (VEGF) antagonist, DC101, was administrated to determine the effect of early angiogenesis and then infiltration of immune cells into tumor and concentration of cytokines were evaluated. RESULTS: The continuous administration of the VEGF receptor 2 antagonist DC101 in the mouse models impeded the infiltration by CD4+ and CD8+ cells into the tumor region. Furthermore, the administration of the VEGF antagonist decreased the amounts of anti-tumoral cytokines such as interleukin (IL)-6 and IL-10. CONCLUSIONS: We revealed that newly formed vessels during tumorigenesis can be channels for particular anti-tumoral immune cells. Our results may confer insight for the clinical development of an efficient antiangiogenic therapeutic manual and a timely chemoprevention to suppress tumor growth.