Bortezomib Effects on Human Microvascular Endothelium in vitro.

Cellular oxidative stress in the endothelium of blood vessels leads to several pathophysiological sequelae, including vascular damage and dysfunction, inflammation and atherosclerosis. Heme oxygenase-1 (HO-1) provides protection against oxidative stress-induced cell death and plays a crucial role in the regulation of cyclooxygenase-2 (COX-2) in endothelial cells. In the present study, we have investigated the effects of bortezomib, a clinically used proteasome inhibitor, on the regulation of HO-1 and COX-2 in cultured human microvascular endothelial cells (HMECs). Bortezomib treatment of HMECS induced dose- and time-dependent expression of HO-1 and COX-2 mRNA and protein, and triggered nuclear translocation of nuclear factor erythroid 2-related transcription factor (Nrf2). These findings suggest that HO-1/COX-2-mediated induction of antioxidant mechanisms via Nrf2 activation may contribute to the cytoprotective effects of bortezomib in microvascular endothelium.