Regulation of macrophage production of vascular endothelial growth factor (VEGF) by hypoxia and transforming growth factor β-1

• DOI: 10.1007/bf02303785
• Publication Date: 2006-02-14T22:13:01Z
• Authors: Judith H. Harmey; Evdokia Dimitriadis; Elaine Kay; H. Paul Redmond; David Bouchier-Hayes
• Keywords: Vascular Endothelial Growth Factor A; Lymphokines; 0303 health sciences; Vascular Endothelial Growth Factors; Macrophages; Breast Neoplasms; Enzyme-Linked Immunosorbent Assay; Endothelial Growth Factors; Prognosis; Immunohistochemistry; Polymerase Chain Reaction; Cell Hypoxia; Monocytes; 3. Good health; 03 medical and health sciences; Transforming Growth Factor beta; Humans; Female; RNA, Messenger; RNA, Neoplasm

Breast tumors contain high numbers of infiltrating macrophages. The role and function of these cells within the tumor remain unclear, but a number of studies have found an association between poor prognosis and macrophage content in human breast cancer. Both hypoxia and TGFbeta-1 have been shown to regulate VEGF in other cell types. We hypothesized that breast tumor-associated macrophages produce VEGF and that macrophage production of this factor is regulated by both hypoxia and TGFbeta-1.Paraffin-embedded breast tumor sections were stained immunohistochemically with anti-VEGF, anti-CD68, and anti-cytokeratin. Monocytes were matured for 3 days in 20% autologous plasma and activated with 1000 U/mL interferon-gamma for 24 hours. Supernatants were assayed for VEGF protein by ELISA. Total RNA was isolated from cells and reverse transcribed to cDNA, which was used as a template in PCR reactions for VEGF and beta-actin.Both tumor cells and tumor macrophages produce VEGF in human breast tumors. Hypoxia increases VEGF protein and mRNA levels in monocyte-derived macrophages, whereas TGFbeta-1 increases VEGF protein but not mRNA under hypoxic growth conditions.Breast tumor-associated macrophages may contribute to the angiogenic activity of human breast tumors by producing VEGF. Macrophage production of VEGF is upregulated by hypoxia and TGFbeta-1, both of which occur in the tumor environment. Macrophage production of VEGF is regulated at both the mRNA and protein levels.