Macrophages mediate inflammation-enhanced metastasis of ovarian tumors in mice.
The tumor microenvironment is known to have a profound effect on tumor progression in a highly context-specific manner. We have investigated whether peritoneal inflammation plays a causative role in ovarian tumor metastasis, a poorly understood process. Implantation of human ovarian tumor cells into the ovaries of severe combined immunodeficient mice resulted in peritoneal inflammation that corresponds temporally with tumor cell dissemination from the ovaries. Enhancement of the inflammatory response with thioglycolate accelerated the development of ascites and metastases. Suppression of inflammation with acetyl salicylic acid delayed ascites development and reduced tumor implant formation. A similar prometastatic effect for inflammation was observed when tumor cells were injected directly into the peritoneum of severe combined immunodeficient mice, and in a syngeneic immunocompetent mouse model. Inflammation-modulating treatments did not affect primary tumor development or in vitro tumor cell growth. Depletion of peritoneal macrophages, but not neutrophils or natural killer cells, reduced tumor progression, as assessed by ascites formation and peritoneal metastasis. We conclude that inflammation facilitates ovarian tumor metastasis by a mechanism largely mediated by macrophages, and which may involve stromal vascular endothelial growth factor production. The confirmation of these findings in immunocompetent mice suggests relevance to human disease. Identifying the mechanisms by which macrophages contribute to tumor metastasis may facilitate the development of new therapies specifically targeting immune cell products in the tumor microenvironment.
Robinson-Smith
Toni M
TM
Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, Ohio 45237, USA.
Isaacsohn
Idit
I
Mercer
Carol A
CA
Zhou
Mingfu
M
Van Rooijen
Nico
N
Husseinzadeh
Nader
N
McFarland-Mancini
Molly M
MM
Drew
Angela F
AF
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D045744:Cell Line, Tumor; D018450:Disease Progression; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007249:Inflammation / Q000276:immunology / Q000473:pathology*; D008264:Macrophages / Q000187:drug effects / Q000276:immunology*; D051379:Mice; D016513:Mice, SCID; D009362:Neoplasm Metastasis / Q000276:immunology / Q000473:pathology*; D009368:Neoplasm Transplantation; D010051:Ovarian Neoplasms / Q000276:immunology / Q000473:pathology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
D000893:Anti-Inflammatory Agents; D042461:Vascular Endothelial Growth Factor A