Low levels of tumor necrosis factor alpha increase tumor growth by inducing an endothelial phenotype of monocytes recruited to the tumor site.
Microenvironmental cues instruct infiltrating tumor-associated myeloid cells to drive malignant progression. A subpopulation of tumor-associated myeloid cells coexpressing endothelial and myeloid markers, although rare in peripheral blood, are primarily associated with tumors where they enhance tumor growth and angiogenesis. These biphenotypic vascular leukocytes result from the endothelial differentiation of myeloid progenitors, a process regulated by tumor necrosis factor (TNF)alpha in vitro. An in vivo increase in tumor-derived TNFalpha expression promoted tumor growth and vascularity of mouse melanoma, lung cancer, and mammary tumors. Notably, tumor growth was accompanied by a significant increase in myeloid/endothelial biphenotypic populations. TNFalpha-associated tumor growth, vascularity, and generation of tumor vascular leukocytes in mouse melanoma tumors were dependent on intact host TNFalpha receptors. Importantly, TNFalpha-expressing tumors did not exhibit increased inflammation over control tumors, suggesting a unique action related to myeloid to endothelial differentiation. Our studies suggest that TNFalpha constitutes a tumor microenvironment signal that biases recruited monocytes toward a proangiogenic/provasculogenic myeloid/endothelial phenotype.
Li
Bin
B
The Department of Veterans Affairs Medical Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
Vincent
Alicia
A
Cates
Justin
J
Brantley-Sieders
Dana M
DM
Polk
D Brent
DB
Young
Pampee P
PP
D000818:Animals; D018827:Carcinoma, Lewis Lung / Q000098:blood supply / Q000378:metabolism / Q000473:pathology*; D002454:Cell Differentiation / Q000187:drug effects; D048708:Cell Growth Processes / Q000187:drug effects; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D018950:Lipopolysaccharide Receptors / Q000096:biosynthesis; D008546:Melanoma, Experimental / Q000098:blood supply / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D008822:Mice, Transgenic; D009000:Monocytes / Q000187:drug effects / Q000473:pathology*; D009389:Neovascularization, Pathologic / Q000378:metabolism / Q000473:pathology; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000378:metabolism / Q000494:pharmacology*
D018950:Lipopolysaccharide Receptors; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha