Abstract
Background The involvement of extracellular vesicles (EVs) in cancer-associated thrombosis (CT)
is unclear. This study aimed to explore the properties of EVs derived from breast
cancer (BC) cells following exposure to high- or low-dose chemotherapeutic agents
and evaluate thrombogenic effects of these EVs on endothelial cells (ECs).
Methods EVs were isolated from BC cell lines (non-metastatic MCF7, high-metastatic MDA-MB-231),
pre-exposed to serum-free medium (control), with or without increasing doses of doxorubicin
or paclitaxel. EV structure and size were studied using electron microscopy and Nano-sight.
Antigen levels were measured by fluorescence-activated cell sorting (FACS). EV effects
on EC thrombogenicity were assessed using FACS, factor Xa chromogenic assay and RT-PCR.
Results Serum-free medium BC cell resulted in EV shedding that additionally increased when
MDA-MB-231 cells were exposed to high doses of both agents. Tissue factor (TF) levels
were similarly low (9–13%) in all EVs compared with the high expression on their parental
MDA-MB-231 cells (76–83%). EVs derived from MDA-MB-231 cells stimulated with high-dose
doxorubicin demonstrated significantly (fivefold; p < 0.001) elevated levels of negatively charged phospholipids, a 97% decrease in TF
pathway inhibitor (TFPI) levels and a sixfold increase (p < 0.001) in procoagulant activity. These EVs also enhanced EC thrombogenicity. Effects
of EVs originating from MCF7 cells were less pronounced.
Conclusion These findings suggest that thrombogenic properties of BC-derived EVs may depend
on the type and dose of the applied chemotherapy agent and may also be affected by
the cell metastatic nature.
Keywords
extracellular vesicles - breast cancer cells - endothelial cells - high-dose chemotherapy
- thrombogenicity
