Tissue-Infiltrating Neutrophils Constitute the Major In Vivo Source of Angiogenesis-Inducing MMP-9 in the Tumor Microenvironment

• Published in: Neoplasia (New York, N.Y.) N.Y.), 2014-10, Vol.16 (10), p.771-788
• Main Authors: Deryugina, Elena I, Zajac, Ewa, Juncker-Jensen, Anna, Kupriyanova, Tatyana A, Welter, Lisa, Quigley, James P
• Format: Article
• Language: English
• Subjects: Angiogenesis Inducing Agents - metabolism; Animals; Cell Line, Tumor; Humans; Macrophages - enzymology; Macrophages - pathology; Male; Matrix Metalloproteinase 9 - genetics; Matrix Metalloproteinase 9 - metabolism; Mice, Inbred C57BL; Mice, Knockout; Neovascularization, Pathologic; Neutrophils - metabolism; Neutrophils - pathology; Oncology; Prostatic Neoplasms - blood supply; Prostatic Neoplasms - enzymology; Prostatic Neoplasms - pathology; Tissue Inhibitor of Metalloproteinase-1 - metabolism; Tumor Microenvironment - physiology; Xenograft Model Antitumor Assays
• ISSN: 1476-5586; 1522-8002; 1476-5586; 1522-8002
• DOI: 10.1016/j.neo.2014.08.013

Abstract According to established notion, one of the major angiogenesis-inducing factors, pro-matrix metalloproteinase-9 (proMMP-9), is supplied to the tumor microenvironment by tumor-associated macrophages (TAMs). Accumulated evidence, however, indicates that tumor-associated neutrophils (TANs) are also critically important for proMMP-9 delivery, especially at early stages of tumor development. To clarify how much angiogenic proMMP-9 is actually contributed by TAMs and TANs, we quantitatively evaluated TAMs and TANs from different tumor types, including human xenografts and syngeneic murine tumors grown in wild-type and Mmp9 -knockout mice. Whereas host MMP-9 competence was required for full angiogenic potential of both normal and tumor-associated leukocytes, direct comparisons of neutrophils versus macrophages and TANs versus TAMs demonstrated that macrophages and TAMs secrete 40- to 50-fold less proMMP-9 than the same numbers of neutrophils or TANs. Correspondingly, the levels of MMP-9–mediated in vivo angiogenesis induced by neutrophils and TANs substantially exceeded those induced by macrophages and TAMs. MMP-9–delivering TANs were also required for development of metastasis-supporting intratumoral vasculature, characterized by ≥ 11-μm size lumens and partial coverage with stabilizing pericytes. Importantly, MMP-9–producing TAMs exhibit M2-skewed phenotype but do not express tissue inhibitor of metalloproteinases-1 (TIMP-1), a novel characteristic allowing them to secrete TIMP-1–free, neutrophil-like MMP-9 zymogen unencumbered by its natural inhibitor. Together, our findings support the notion whereby TANs, capable of immediate release of their pre-stored cargo, are the major contributors of highly angiogenic MMP-9, whereas tumor-influxing precursors of macrophages require time to differentiate, polarize into M2-skewed TAMs, shut down their TIMP-1 expression, and only then, initiate relatively low-level production of TIMP-free MMP-9 zymogen.