Endothelial cell colony forming units derived from malignant breast diseases are resistant to tumor necrosis factor-α-induced apoptosis

Mobilisation of endothelial progenitor cells (EPCs) from the bone marrow is a crucial step in the formation of de novo blood vessels, and levels of peripheral blood EPCs have been shown to be elevated in certain malignant states. Using flow cytometry and a Hill-based colony forming unit (CFU) assay, the present study indicated that higher levels of CD34 and vascular endothelial growth factor receptor 2 (VEGFR2) double-positive EPCs, as well as increased formation of endothelial cell colony-forming units (EC-CFUs) are associated with benign and malignant breast diseases, providing possible indicators for breast disease detection. Gene expression profiles revealed a genetic difference between CD34(+) VEGFR2(+) EPCs and EC-CFUs. Decreased expression of tumour necrosis factor receptor 2 (TNFR2) signalling-related genes and inhibition of tumour necrosis factor (TNF)-induced signalling were demonstrated in EC-CFUs derived from patients with malignant breast disease in comparison with those from healthy controls. Interestingly, our data provided the first evidence that EC-CFUs derived from patients with malignant breast disease were resistant to TNF-alpha-induced apoptosis, indicating a plausible target for future therapeutic interventions.