Effect and mechanisms of bevacizumab in breast cancer xenograft radiotherapy model

Objective To observe the radiosensiti.zing activity of bevacizumab on breast cancer xenograft model,and to explore its possible mechanisms.Methods Thirty mice with subcutaneous transplantation tumor were randomly divided into group of bevacizumab in combination with radiotherapy,radiotherapy alone group and normal control group,and the effect of bevacizumab on breast cancer xenograft was studied.By using Western blotting and immunohistochemistry,the expression of hypoxia-inducible factor-1α (HIF-1o),vascular endothelial growth factor (VEGF),proliferating cell nuclear antigen (Ki-67),and platelet and endothelial cell adhesion molecule (CD31) was detected in tumor tissues.Results The subcutaneous xenograft in combination group was decreased significantly as compared with radiotherapy alone group (P ＜ 0.05).Immunohistochemistry revealed that combination group expressed the weakest set of Ki-67,HIF-1 α and CD31 (P ＜ 0.05).Western blotting showed that combination group also had the weakest expression of HIF-1α and VEGF.Conclusion Bevacizumab could play a role of radiosensitization in breast cancer subcutaneous transplantation tumor,which was induced by the inhibition of HIF-1 o,VEGF expression and suppression of tumor cell proliferation and angiogenesis. Key words: Bevacizumab ;  Radiation therapyr;  Xenograft ;  Breast cancer