Anti-CCL-2 / MCP-1 (monocyte chemoattractant protein-1) monoclonal antibodies effectively inhibit tumor angiogenesis and growth of human breast carcinoma

1090 C-C chemokine ligand-2 (CCL-2), otherwise known as monocyte chemoattractant protein-1 (MCP-1) is a potent chemoattractant of monocytes that has recently been indicated to play a pivotal role in tumor angiogenesis and growth. In a number of cancer types, including breast cancer, squamous cell carcinoma of head and neck, gastric carcinoma, and hemangioma, CCL-2 expression levels in the primary tumor correlate with blood vessel density, disease staging and prognosis. It has been postulated that CCL-2 recruits tumor-infiltrating macrophages and activates these infiltrating cells to produce angiogenic growth factors such as vascular endothelial growth factor (VEGF) and interleukin-8. These factors in turn stimulate tumor angiogenesis and contribute to cancer disease progression. We explored the role of CCL-2 in tumor angiogenesis in an in vivo angiogenesis model employing human breast cancer cells expressing different levels of CCL-2. Matrigel plugs containing MDA-MB-435S or MDA-MB-231 human breast cancer cells, which secrete 6000 pg/ml/10E6 cells/24 hr and 30 pg/ml/10E6 cells/24 hr CCL-2 in vitro respectively, were implanted subcutaneously (s.c.) in nude mice. Hemoglobin levels in the Matrigel plugs were measured to determine the degree of angiogenic response elicited by the tumor cells. The potency of angiogenic response induced by the two cancer cell lines correlated well with CCL-2 production levels in these cells, supporting the hypothesis that CCL-2 is an angiogenic mediator. The in vivo angiogenic potential of MDA-MB-435S cells was dose-dependently inhibited by anti-CCL-2 monoclonal antibodies, despite the complexity and redundancy of angiogenic growth factors produced by these tumor cells. Furthermore, we explored the tumor inhibitory effect of blocking CCL-2 bioactivity on xenograft human breast cancer models in nude and SCID mice. Prophylactic and early treatment with anti-human CCL-2 antibody in combination with anti-mouse JE antibody significantly inhibited MDA-MB-435S-GFP xenograft human breast tumor growth in nude and SCID mice. A significant reduction in tumor burden was seen in the anti-CCL-2 treated animals compared to the PBS-treated or control IgG-treated animals (p