Figure 6
Mechanism of action of TGF-β antagonists in vivo. Lung metastases from mice treated with LY2109761 and 1D11 were stained for markers of cell proliferation (Ki-67), apoptosis (TUNEL), and microvascular endothelial cells (CD34). At least 600 nuclei were counted in 5 randomly selected high-power (400 ×) fields in areas of viable tumor to determine the proportion of Ki-67-or TUNEL-positive cells. The total number of CD34+ microvessels were counted in 5 randomly selected high-power (400 ×) fields in areas of viable tumor. A. Neither antagonist affected tumor cell proliferation (Ki-67; p = 0.49 for the LY2109761 group and p = 0.12 for the 1D11 group) or B. apoptosis (TUNEL assay; p = 0.12 for the LY2109761 group and p = 0.06 for the 1D11 group). C. However, microvessel density was significantly reduced in tumors of mice treated with LY2109761 and 1D11 compared with their respective controls (p = 0.018 for the LY2109761 group and p = 0.024 for the 1D11 group). D. Histological staining for tartrate resistant acid phosphatase (TRAP) activity (red color) of bone metastases from representative vehicle-(left images) and 1D11-treated (right images) mice. The numbers of TRAP positive cells per mm2 of tumor adjacent to bone in bone metastases from 1D11-treated mice (n = 9 lesions) relative to vehicle-treated mice (n = 17 lesions) are shown. Treatment with 1D11 was associated with a significant reduction in the number of TRAP-positive osteoclasts (p = 0020). Unpaired 2-sided t-test (± Welch correction) was used for comparisons.