Gr-1+CD11b+ cells facilitate Lewis lung cancer recurrence by enhancing neovasculature after local irradiation

Studies have shown that bone marrow-derived cells play an important role in tumor recurrence after chemotherapy and radiotherapy. In this study, we examined the relationship between the accumulation of Gr-1+CD11b+ cells and tumor recurrence after irradiation in tumor-bearing mice. By transplanting bone marrow cells into whole body-irradiated mice depleted of bone marrow, we assessed the role of Gr-1+CD11b+ cells in lung carcinoma models after local irradiation (LI). 20 Gy local irradiation could recruit CD11b+CXCR4+ cells into the irradiated tissues, and the recruited CD11b+CXCR4+ cells could promote tumor recurrence. Further 6 Gy whole body irradiation (WBI6Gy) could decrease tumor recurrence by inhibiting the accumulation of Gr-1+CD11b+ cells and then suppressing tumor vasculogenesis and angiogenesis. Our results suggest that the accumulation of CD11b+Gr-1+ cells promote tumor re-growth after local irradiation by enhancing tumor neovascularization, and low dose of whole body irradiation or irradiation of enlarged spleen may provide a new alternative for anti-angiogenesis therapies.