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Two vascular growth factor families, VEGF and the angiopoietins, play critical and coordinate roles in tumor progression and metastasis. A single inhibitor targeting both VEGF and angiopoietins is not available. Here, we developed a chimeric decoy receptor, namely double anti-angiogenic protein (DAAP), which can simultaneously bind VEGF-A and angiopoietins, blocking their actions. Compared to VEGF-Trap or Tie2-Fc, which block either VEGF-A or angiopoietins alone, we believe DAAP is a highly effective molecule for regressing tumor angiogenesis and metastasis in implanted and spontaneous solid tumors; it can also effectively reduce ascites formation and vascular leakage in an ovarian carcinoma model. Thus, simultaneous blockade of VEGF-A and angiopoietins with DAAP is an effective therapeutic strategy for blocking tumor angiogenesis, metastasis, and vascular leakage.

Abstract-Vascular enlargement is a characteristic feature of angiopoietin-1 (Ang1)-induced changes in adult blood vessels. However, it is unknown whether tissues having Ang1-mediated vascular enlargement have more blood flow or whether the enlargement is reversible. We have recently created a soluble, stable and potent Ang1 variant, COMP-Ang1.In the present study, we investigated the effects of varied dose and duration of COMP-Ang1 on vascular enlargement and blood flow in the tracheal microvasculature of adult mice and explored a possible mechanism of long-lasting vascular enlargement. We found that COMP-Ang1 administered by adenoviral vector induced long-lasting vascular enlargement and increased tracheal blood flow. In contrast, short-term administration of COMP-Ang1 recombinant protein induced transient vascular enlargement that spontaneously reversed within a month. In both cases, the vascular enlargement resulted from endothelial proliferation. The COMP-Ang1-induced vascular remodeling is mediated mainly through Tie2 activation. Sustained overexpression of Tie2 could participate in the maintenance of vascular changes. Together, our findings indicate that sustained treatment with COMP-Ang1 can produce long-lasting vascular enlargement and increased blood flow. Key Words: angiopoietin-1 Ⅲ COMP-Ang1 Ⅲ vascular enlargement Ⅲ blood flow A ngiopoietin-1 (Ang1) is known to be a ligand to Tie2 tyrosine kinase receptor expressed on endothelial cells. 1 Ang1/Tie2 signaling is thought be involved in branching and remodeling of the primitive vascular network and in the recruitment of mural cells during development. 2,3 Transgenic overexpression of Ang1 using the skin-specific keratin-14 promoter produces leakage-resistant and enlarged vessels with an increased number of endothelial cells in skin. 4,5 Gene transfer of Ang1 into ischemic tissues produces notably enlarged blood vessels. 6,7 Baffert et al recently identified that Ang1-induced vascular enlargement could be the result of endothelial proliferation in trachea mucosa. 8 Thus, a cardinal feature of Ang1-induced vascular remodeling is vascular enlargement resulting from endothelial cell proliferation in adult animals. 4 -8 Given that Ang1-induced therapeutic benefits correlated with vascular enlargement in the ischemic tissues, 6,7,9 enhanced blood flow through blood vessels enlarged by Ang1 treatment could provide a great therapeutic benefit to ischemic peripheral tissues. However, it is not known whether the tissues having Ang1-mediated enlarged vessels have more blood flow. In addition, the effective dose and treatment period of Ang1 for inducing effective vascular enlargement is not known. Moreover, it is not known whether Ang1-mediated vascular enlargement regresses when Ang1 stimulation is withdrawn.We have recently developed a soluble, stable, and potent Ang1 variant, COMP-Ang1. 10 To create this protein, we replaced the amino-terminal portion of Ang1 with the short coiled-coil domain of cartilage oligomeric matrix protein (COMP). COMP-Ang1 is more po...

Materials and Methods Cell Transfections and ImmunoblottingCysteines 65