Plasticity in tumor-promoting inflammation: impairment of macrophage recruitment evokes a compensatory neutrophil response

JC Pahler, S Tazzyman, N Erez, YY Chen, C Murdoch… - Neoplasia, 2008 - Elsevier
JC Pahler, S Tazzyman, N Erez, YY Chen, C Murdoch, H Nozawa, CE Lewis, D Hanahan
Neoplasia, 2008Elsevier
Previous studies in the K14-HPV/E 2 mouse model of cervical carcinogenesis demonstrated
that infiltrating macrophages are the major source of matrix metalloproteinase 9 (MMP-9), a
metalloprotease important for tumor angiogenesis and progression. We observed increased
expression of the macrophage chemoattractant, CCL2, and its receptor, CCR2, concomitant
with macrophage influx and MMP-9 expression. To study the role of CCL2-CCR2 signaling
in cervical tumorigenesis, we generated CCR2-deficient K14-HPV/E 2 mice. Cervixes of …
Abstract
Previous studies in the K14-HPV/E2 mouse model of cervical carcinogenesis demonstrated that infiltrating macrophages are the major source of matrix metalloproteinase 9 (MMP-9), a metalloprotease important for tumor angiogenesis and progression. We observed increased expression of the macrophage chemoattractant, CCL2, and its receptor, CCR2, concomitant with macrophage influx and MMP-9 expression. To study the role of CCL2-CCR2 signaling in cervical tumorigenesis, we generated CCR2-deficient K14-HPV/E2 mice. Cervixes of CCR2-null mice contained significantly fewer macrophages. Surprisingly, there was only a modest delay in time to progression from dysplasia to carcinoma in the CCR2-deficient mice, and no difference in end-stage tumor incidence or burden. Moreover, there was an unexpected persistence of MMP-9 activity, associated with increased abundance of MMP-9+ neutrophils in tumors from CCR2-null mice. In vitro bioassays revealed that macrophages produce soluble factor(s) that can suppress neutrophil dynamics, as evidenced by reduced chemotaxis in response to CXCL8, and impaired invasion into three-dimensional tumor masses grown in vitro. Our data suggest a mechanism whereby CCL2 attracts proangiogenic CCR2+ macrophages with the ancillary capability to limit infiltration by neutrophils. If such tumor-promoting macrophages are suppressed, MMP-9+ neutrophils are then recruited, providing alternative paracrine support for tumor angiogenesis and progression.
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