Objective To investigate the specificity of NRP-1 monoclonal antibody (NRP-1 MAb), and the antitumor effect of NRP-1 MAb at the different doses on nude mice bearing breast cancer xenografts.

Methods The recognition of NRP-1 protein in MCF7 cells by NRP-1 MAb were detected by Western blot and confocal immunofluorescent analysis. BALB/c nude mice were adopted to establish a tumor-bearing model by inoculating subcutaneously MCF7 cells, and then the passage of tumor tissues was carried out. When the tumor grew to 300-500 mm³, the xenografts nude mice were randomly divided into control group, low-dose group, middle-dose group and high-dose group, 6 mice in each group, and 7 doses in full course by subcutaneous injection. Then we observed the general status, tumor size and body weight in the routine. When the trial ended, relevant tumors were striped and weighed, and then we extracted the protein. Western blot was performed to examine the expression of VEGF and NRP-1.

Results NRP-1 MAb could bind the NRP-1 protein in MCF7 cells, and significantly inhibit the growth of breast cancer xenograft in nude mice. The corresponding inhibition ratio reached 47.01%, 65.70% and 69.19% in low-dose group, middle-dose group and high-dose group, respectively.

Conclusion NRP-1 MAb could recognize and bind NRP-1 on the membrane of MCF7 cells and inhibit the growth of the transplanted tumor. The downregulation of VEGF and NRP-1 may play an active role in tumor growth inhibition.