Reactive oxygen species and glutathione level changes by a proteasome inhibitor, MG132, partially affect calf pulmonary arterial endothelial cell death

MG132 as a proteasome inhibitor has been shown to induce apoptotic cell death through the formation of reactive oxygen species (ROS). Here, we evaluated the effects of MG132 on the growth of endothelial cells (ECs), especially calf pulmonary artery endothelial cells (CPAECs), in relation to cell death, ROS, and glutathione (GSH) levels. MG132 dose dependently inhibited the growth of CPAEC and human umbilical vein endothelial cells (HUVECs) at 24 hours. MG132 also induced apoptotic cell death in CPAEC, which were accompanied by the loss of mitochondrial membrane potential (MMP; ΔΨm). MG132 increased ROS levels, including O2^•- in CPAEC, but not in HUVEC. MG132 also dose dependently increased GSH-depleted cells in both ECs. N-acetyl-cysteine (NAC; a well-known antioxidant) reduced ROS levels in MG132-treated CPAEC with the slight prevention of cell death and GSH depletion. Buthionine sulfoximine (BSO; an inhibitor of GSH synthesis) increased ROS levels and decreased GSH levels in MG132-treated CPAEC without the enhancement of cell death. In conclusion, MG132 inhibited the growth of ECs, especially CPAEC. The changes of ROS and GSH levels by MG132 partially affect CPAEC death.