Figure 4. DA inhibits EPC mobilization, which in turn is associated with inhibition of tumor growth and angiogenesis.

(A) Graphical representation of the tumor volume of tumor-bearing S180 plus DA and D₂^(–/–) plus S180 plus DA-treated animals. Significant reduction was observed in the tumor volume of DA-treated S180 tumor-bearing animals. In D₂^(–/–) plus S180 animals, tumor growth was higher than in tumor-bearing controls. However, no effect of DA treatment was observed in D₂^(–/–) plus S180 animals. (B, C, and F) Immunohistochemical staining of CD31 (microvessel density), a specific endothelial cell marker, showed significantly reduced microvessel density in tumor tissues following DA treatment in comparison with the vehicle-treated controls. (B, D, and F) Tumor microvessel density was significantly higher in D₂^(–/–) plus S180 animals (P < 0.05 compared with respective control). (D–F) DA treatment failed to reduce the microvessel density in tumor-bearing D₂^(–/–) animals. Microvessel density was measured by counting the number of microvessels in 10 randomly chosen high-power microscopic fields within the sections. Figures are representative of 4 separate experiments for each group. *P < 0.05. Scale bars: 50 μm.