J. Cancer Mol. 2: 155-160, 2006

[Research Paper]

Tumor Necrosis Factor-alpha, Interleukin-8 and Interleukin-6 Are Involved in Vascular Endothelial Cell Capillary Tube and Network Formation Induced by Tumor-Associated Macrophages

Chun-Chung Lee, Ko-Jiunn Liu, Li-Li Chen, Yu-Chen Wu, and Tze-Sing Huang

National Institute of Cancer Research, National Health Research Institutes, Taipei, Taiwan

Abstract:

AIM: The goal of this study is to investigate the involvement of inflammatory cytokines produced by tumor-associated macrophages in promoting tumor angiogenesis.

METHODS: To study the angiogenic effect of tumor-associated macrophages (TAMs), we overlaid human umbilical vein endothelial cells on top of Matrigel containing MCF-7 breast cancer cells with or without macrophages and investigated the outcome of endothelial cell capillary tube and network formation.  We also determined the levels of interleukin (IL)-1beta, IL-6, IL-8, IL-10, IL-12p70, tumor necrosis factor-alpha (TNF-alpha), and vascular endothelial growth factor (VEGF) in the media of MCF-7 breast cancer cells co-cultivated with or without macrophages.  Furthermore, anti-IL-8 receptor antagonizing antibody, IL-6 or TNF-alpha soluble receptor, and inhibitors against NF-kB, MEK, p38^MAPK, and JNK, respectively, were used to determine which signal transduction pathways are involved in TAMs-induced angiogenic activity.

RESULTS: The Matrigel mixed with MCF-7 cells and macrophages was more efficient than 100 ng/ml of VEGF to induce vascular endothelial cell tube and network formation.  The expression of IL-6, IL-8 and TNF-alpha were significantly enhanced by co-cultivation of MCF-7 cells with macrophages.  The promotion of capillary tube and network formation by TAMs was inhibited either with anti-IL-8 receptor antagonizing antibody or with IL-6 or TNF-alpha soluble receptor, suggesting that IL-8, TNF-alpha and IL-6 indeed participated in TAMs-induced angiogenesis.  In addition, TAMs-induced angiogenic activity could also be attenuated by the presence of inhibitors against NF-kB, ERK, and p38^MAPK signaling pathways.

CONCLUSION: IL-8, TNF-alpha and IL-6 were involved in TAMs-associated angiogenesis via NF-kB, ERK, and p38^MAPK-dependent signaling pathways.

Received 7/24/06; Revised 8/10/06; Accepted 8/11/06.

¹Correspondence: Dr. Tze-Sing Huang, National Institute of Cancer Research, National Health Research Institutes, 7F, No. 161, Min-Chuan East Road Section 6, Taipei 114, Taiwan, Republic of China. Phone: 886-2-2653 4401 ext 25138. Fax: 886-2-2792 9654. E-mail: tshuang@nhri.org.tw

²Abbreviation: TAM, tumor-associated macrophages; VEGF, vascular endothelial growth factor; bFGF, basic fibroblast growth factor; TNF-alpha, tumor necrosis factor-alpha; IL, interleukin; TGF-beta, transforming growth factor-beta; MMPs, matrix metalloproteinases; PBMCs, peripheral blood mononuclear cells; HUVECs, human umbilical vein endothelial cells; MCP-1, monocyte chemotactic protein-1; GM-CSF, granulocyte-macrophage colony-stimulating factor.