Growth-related oncogene-α induces endothelial dysfunction through oxidative stress and downregulation of eNOS in porcine coronary arteries

Growth-related oncogene-α (GRO-α) is a member of the CXC chemokine family, which is involved in the inflammatory process including atherosclerosis. We hypothesized that GRO-α may affect endothelial functions in both porcine coronary arteries and human coronary artery endothelial cells (HCAECs). Vasomotor function was analyzed in response to thromboxane A2 analog U-46619 for contraction, bradykinin for endothelium-dependent vasorelaxation, and sodium nitroprusside (SNP) for endothelium-independent vasorelaxation. In response to 10^-6 M bradykinin, GRO-α (50 and 100 ng/ml) significantly reduced endothelium-dependent vasorelaxation by 34.73 and 48.8%, respectively, compared with controls (P < 0.05). There were no changes in response to U-46619 or SNP between treated and control groups. With the lucigenin-enhanced chemiluminescence assay, superoxide anion production in GRO-α-treated vessels (50 and 100 ng/ml) was significantly increased by 50 and 86%, respectively, compared with controls (P < 0.05). With real-time PCR analysis, endothelial nitric oxide synthase (eNOS) mRNA levels in porcine coronary arteries and HCAECs after GRO-α treatment were significantly decreased compared with controls (P < 0.05). The eNOS protein levels by both immunohistochemistry and Western blot analyses were also decreased in GRO-α-treated vessels. Antioxidant seleno-L-methionine and anti-GRO-α antibody effectively blocked these effects of GRO-α on both porcine coronary arteries and HCAECs. In addition, GRO-α immunoreactivity was substantially increased in the atherosclerotic regions compared with nonatherosclerotic regions in human coronary arteries. Thus GRO-α impairs endothelium-dependent vasorelaxation in porcine coronary arteries through a mechanism of overproduction of superoxide anion and downregulation of eNOS. GRO-α may contribute to human coronary artery disease.