Inhibition of cyclo-oxygenase 2 reduces tumor metastasis and inflammatory signaling during blockade of vascular endothelial growth factor

Jason C Fisher,Paolo Guarnieri,Kathleen O'Toole,Sonia L Hernandez,Yan-Jung Chang,Jianzhong Huang,Darrell J Yamashiro,Mary Haley,Jeffrey W Gander,Tessa B Johung,Jessica J Kandel

doi:10.1186/2045-824x-3-22

Abstract

Vascular endothelial growth factor (VEGF) blockade is an effective therapy for human cancer, yet virtually all neoplasms resume primary tumor growth or metastasize during therapy. Mechanisms of progression have been proposed to include genes that control vascular remodeling and are elicited by hypoperfusion, such as the inducible enzyme cyclooxygenase-2 (COX-2). We have previously shown that COX-2 inhibition by the celecoxib analog SC236 attenuates perivascular stromal cell recruitment and tumor growth. We therefore examined the effect of combined SC236 and VEGF blockade, using the metastasizing orthotopic SKNEP1 model of pediatric cancer. Combined treatment perturbed tumor vessel remodeling and macrophage recruitment, but did not further limit primary tumor growth as compared to VEGF blockade alone. However, combining SC236 and VEGF inhibition significantly reduced the incidence of lung metastasis, suggesting a distinct effect on prometastatic mechanisms. We found that SC236 limited tumor cell viability and migration in vitro, with effects enhanced by hypoxia, but did not change tumor proliferation or matrix metalloproteinase expression in vivo. Gene set expression analysis (GSEA) indicated that the addition of SC236 to VEGF inhibition significantly reduced expression of gene sets linked to macrophage mobilization. Perivascular recruitment of macrophages induced by VEGF blockade was disrupted in tumors treated with combined VEGF- and COX-2-inhibition. Collectively, these findings suggest that during VEGF blockade COX-2 may restrict metastasis by limiting both prometastatic behaviors in individual tumor cells and mobilization of macrophages to the tumor vasculature.

Highlights

Agents that inhibit vascular endothelial growth factor (VEGF) signaling are increasingly incorporated into treatment regimens for metastatic human cancer, yet the overall benefit of this treatment strategy has been relatively modest [ 1, 2]
Our data demonstrates that SC236 when combined with VEGF blockade can markedly reduce distant metastasis, it does not alter primary SKNEP1 tumor size, suggesting a differential effect on this aspect of tumor progression
We asked whether SC236 caused changes in metastasis-related tumor cell behaviors under conditions imposed by VEGF blockade, including proliferation, activation of matrix metalloproteases (MMP) -2 and -9 and ability to invade basement membrane. (A)COX-2 is known to modulate tumor cell proliferation, and we previously found that SC236 decreased tumor proliferation in vivo

Summary

Introduction

Agents that inhibit vascular endothelial growth factor (VEGF) signaling are increasingly incorporated into treatment regimens for metastatic human cancer, yet the overall benefit of this treatment strategy has been relatively modest [ 1, 2]. Both clinical and experimental studies indicate that many or most malignancies will progress if VEGF blockade is sustained, and that progression may involve both progressive primary tumor growth and enhanced metastasis. We previously found that VEGF inhibition significantly reduced primary tumor growth and the incidence of spontaneous lung metastasis in the orthotopic renal SKNEP1 tumor model over a six week treatment period, and regressed established metastases in late-stage tumors [ 3, 4]. Recruitment of COX-2-expressing macrophages can create an inflammatory proangiogenic environment that strongly promotes tumor growth [ 12]

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