Aim: The purpose of this study was to determine if the in vitro age of endothelial cells alters endothelial response(s) to breast cancer cells.
Method: After characterizing lower passage ("young"; passages 10-16) and higher passage ("old"; passages 30-36) bovine pulmonary artery endothelial cells (BPAECs), fluorescently labeled MCF-7 breast cancer cells were added to confluent monolayers of young and old BPAECs.
Results: Transient gaps that peaked in size by 12 h and closed by 48h occurred between the young BPAECs, while large persistent gaps formed between the old BPAECs. Gap formation did not occur when 184A1 cells, a non-malignant mammary epithelial cell line, were added in place of MCF-7 cells, suggesting that the age-related responses of the endothelial cells to MCF-7 cell addition were specific to the tumor cell addition. Additionally, more MCF-7 cells migrated through old BPAEC monolayers, than young BPAEC monolayers, grown on Matrigel-coated filters. Finally, DNA fragmentation and fluorescent annexin-V binding assays suggested increased MCF-7 cell-induced apoptosis in older BPAECs, though results from a caspase-3 activation assay were equivocal.
Conclusions: In sum, our findings support the notion that aged endothelial cells are more susceptible to breast cancer-induced injury, perhaps due to increased apoptosis.