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


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Harmey
J H
JH
Royal College of Surgeons in Ireland, Department of Surgery, Beaumont Hospital, Dublin.
Dimitriadis
E
E
Kay
E
E
Redmond
H P
HP
Bouchier-Hayes
D
D
D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D015687:Cell Hypoxia / Q000502:physiology*; D016228:Endothelial Growth Factors / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008222:Lymphokines / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism*; D009000:Monocytes; D016133:Polymerase Chain Reaction; D011379:Prognosis; D012333:RNA, Messenger / Q000235:genetics*; D012334:RNA, Neoplasm / Q000235:genetics*; D016212:Transforming Growth Factor beta / Q000502:physiology*; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D016228:Endothelial Growth Factors; D008222:Lymphokines; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D016212:Transforming Growth Factor beta; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors