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Cross‐talk between endothelial and breast cancer cells regulates reciprocal expression of angiogenic factors in vitro
Author(s) -
Buchanan Cara F.,
Szot Christopher S.,
Wilson Tia D.,
Akman Steven,
MethenyBarlow Linda J.,
Robertson John L.,
Freeman Joseph W.,
Rylander Marissa Nichole
Publication year - 2012
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.23447
Subject(s) - angiogenesis , endothelial stem cell , neovascularization , biology , cancer cell , cancer research , tumor microenvironment , in vitro , cell culture , vascular endothelial growth factor a , vascular endothelial growth factor , microbiology and biotechnology , cancer , biochemistry , tumor cells , vegf receptors , genetics
Reciprocal growth factor exchange between endothelial and malignant cells within the tumor microenvironment may directly stimulate neovascularization; however, the role of host vasculature in regulating tumor cell activity is not well understood. While previous studies have examined the angiogenic response of endothelial cells to tumor‐secreted factors, few have explored tumor response to endothelial cells. Using an in vitro co‐culture system, we investigated the influence of endothelial cells on the angiogenic phenotype of breast cancer cells. Specifically, VEGF, ANG1, and ANG2 gene and protein expression were assessed. When co‐cultured with microvascular endothelial cells (HMEC‐1), breast cancer cells (MDA‐MB‐231) significantly increased expression of ANG2 mRNA (20‐fold relative to MDA‐MB‐231 monoculture). Moreover, MDA‐MB‐231/HMEC‐1 co‐cultures produced significantly increased levels of ANG2 (up to 580 pg/ml) and VEGF protein (up to 38,400 pg/ml) while ANG1 protein expression was decreased relative to MDA‐MB‐231 monocultures. Thus, the ratio of ANG1:ANG2 protein, a critical indicator of neovascularization, shifted in favor of ANG2, a phenomenon known to correlate with vessel destabilization and sprouting in vivo. This angiogenic response was not observed in nonmalignant breast epithelial cells (MCF‐10A), where absolute protein levels of MCF‐10A/HMEC‐1 co‐cultures were an order of magnitude less than that of the MDA‐MB‐231/HMEC‐1 co‐cultures. Results were further verified with a functional angiogenesis assay demonstrating well‐defined microvascular endothelial cell (TIME) tube formation when cultured in media collected from MDA‐MB‐231/HMEC‐1 co‐cultures. This study demonstrates that the angiogenic activity of malignant mammary epithelial cells is significantly enhanced by the presence of endothelial cells. J. Cell. Biochem. 113: 1142–1151, 2012. © 2011 Wiley Periodicals, Inc.