A detailed understanding of the assortment of genes that are expressed in
breast tumor vessels is needed to facilitate the development of novel, molecularly targeted anti-angiogenic agents for
breast cancer therapies. Rapid immunohistochemistry using
factor VIII-related
antibodies was performed on sections of frozen human
luminal-A
breast tumors (n = 5) and normal breast (n = 5), followed by
laser capture microdissection of vascular cells.
RNA was extracted and amplified, and fluorescently labeled
cDNA was synthesized and hybridized to 44,000-element long-
oligonucleotide DNA microarrays. Statistical analysis of microarray was used to compare differences in gene expression between
tumor and normal vascular cells, and Expression Analysis Systematic Explorer was used to determine enrichment of gene ontology categories.
Protein expression of select genes was confirmed using immunohistochemistry. Of the 1176 genes that were differentially expressed between
tumor and normal vascular cells, 55 had a greater than fourfold increase in expression level. The extracellular matrix gene ontology category was increased while the ribosome gene ontology category was decreased. Fibroblast activation
protein, secreted
frizzled-related protein 2,
Janus kinase 3, and neutral
sphingomyelinase 2
proteins localized to
breast tumor endothelium as assessed by immunohistochemistry, showing significantly greater staining compared with normal tissue. These
tumor endothelial marker
proteins also exhibited increased expression in
breast tumor vessels compared with that in normal tissues. Therefore, these
genetic markers may serve as potential targets for the development of
angiogenesis inhibitors.