Cyclophosphamide enhances TNF-α-induced apoptotic cell death in murine vascular endothelial cell

Cyclophosphamide (CPA) is one of the therapeutic agents for systemic inflammatory disorders. In murine dermal endothelial cells (F-2), 4-hydroxycyclophosphamide (4-HC), which is active metabolite of CPA, enhanced TNF-α-induced DNA fragmentation. In addition, 4-HC was shown to elevate TNF-α-induced caspase-3 activation. Caspase-8 activation was identified by the treatment of TNF-α, whereas 4-HC was no effect. In contrast, only when treated with 4-HC, caspase-9 activation and the increase in the intracellular expression of Bax were detected. These results suggest that CPA may sensitize endothelial cells to TNF-α-induced apoptosis through a mitochondria-dependent pathway and clinically may contribute to the limitation of inflammatory process.