Background-Multiple pathways contribute to accelerated coronary atherosclerosis in diabetics, including increased oxidative stress and inflammatory burden. Accordingly, the mechanisms of abnormal formation of reactive oxygen species and the changes in inflammatory gene expression were examined in diabetic coronary arteries. Methods and Results-In pigs with streptozotocin-induced diabetes, superoxide formation was augmented in coronary media and adventitia because of increased NAD(P)H oxidase activity (3 months) accompanied by upregulated expression of its cytosolic subunit, p22 phox . Diabetes-induced oxidative stress resulted in the inflammatory response in the adventitia (increased expression of interleukin-6, tumor necrosis factor-␣, monocyte chemotactic protein-1, vascular cell adhesion molecule-1 [VCAM-1]) and in the media (VCAM-1). To examine the mechanisms of these changes, studies with isolated coronary fibroblasts were undertaken. Advanced glycation end products (AGEs), rather than glucose itself, upregulated expression of interleukin-6, VCAM-1, and monocyte chemotactic protein-1 mRNAs. These results were paralleled by increased interleukin-6 secretion (PϽ0.01) and augmented leukocyte adhesion to AGEstimulated coronary cells (PϽ0.001). AGEs increased expression of phosphorylated forms of mitogen-activated protein kinases in coronary cells (ERK1/2 and JNK) and resulted in redox-sensitive expression of inflammatory genes that was inhibited by several inhibitors of oxidative pathways [NAD(P)H oxidase inhibitors, N-acetylcysteine, and pyrrolidine dithiocarbamate]. Conclusions-Diabetes

Silibinin is a natural flavonoid antioxidant with anti-hepatotoxic properties and pleiotropic anticancer capabilities. We tested the hypothesis that silibinin inhibits cellular invasiveness by down-regulating the focal adhesion kinase (FAK) and extracellular signal-regulated protein kinase (ERK)-dependent c-Jun/activator protein-1 (AP-1) induction, which leads to inhibition of urokinase-type plasminogen activator (u-PA) and matrix metalloproteinase-2 (MMP-2) expressions in human osteosarcoma MG-63 cells. We found that silibinin decreased cell adhesion and invasiveness, as well as inhibited u-PA and MMP-2 expressions. Silibinin reduced ERK 1/2 phosphorylation, but had no effects on the phosphorylation of c-Jun N-terminal kinases (JNKs) 1/2, p38 and Akt. Silibinin suppressed AP-1-binding activity and c-Jun levels and its phosphorylation without changes of c-Fos and Ets-1 levels. Silibinin also inhibited interleukin-6-induced ERK 1/2 and c-Jun phosphorylation, and cell invasiveness. Thus, silibinin may possess an anti-metastatic activity in MG-63 cells.