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Background/Aim: The abnormal growth of vascular smooth muscle cells (VSMCs) induced by reactive oxygen species (ROS) is considered a major pathogenic process in vascular diseases. Interleukin (IL)-24 specifically inhibits cancer cell growth through the induction of cell cycle arrest and apoptosis. However, the role of IL-24 in ROS-induced VSMC growth has not yet been investigated. Methods: An MTT assay, gene expression analysis, flow cytometry and a scratch wound healing assay were performed to determine the anti-growth effects of IL-24 in H2O2-treated mouse vascular aortic smooth muscle (MOVAS) cells. To elucidate the effect of IL-24 on ROS-induced signaling, Western blot analysis was employed. Results: IL-24 inhibited the growth of normal MOVAS cells treated with H2O2 by inducing a cell cycle arrest at the G0/G1 phase through the regulation of p21 and cyclin D1. Furthermore, IL-24 suppressed mRNA expression of vascular endothelial growth factor and platelet-derived growth factor and subsequently decreased the level of cell migration in response to H2O2. Interestingly, IL-24 attenuated the H2O2-induced ROS production by reducing the mitochondrial H2O2 production and enhancing the expression of antioxidant enzymes. We also showed that the ability of H2O2 to induce the PI3K/Akt and Erk signaling pathways was blocked by IL-24. Conclusion: These findings suggest a novel mechanism in which IL-24 suppresses the growth of normal VSMCs by inhibiting H2O2-induced ROS production through the regulation of mitochondrial ROS production and expression of antioxidant enzymes. Copyright © 2012 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Vascular calcification plays a role in the pathogenesis of atherosclerosis, diabetes, and chronic kidney disease; however, the role of apurinic/apyrimidinic endonuclease 1/redox factor-1 (APE1/Ref-1) in inorganic phosphate (Pi)-induced vascular smooth muscle cell (VSMC) calcification remains unknown. In this study, we investigated the possible role of APE1/Ref-1 in Pi-induced VSMC calcification. We observed that Pi decreased endogenous APE1/Ref-1 expression and promoter activity in VSMCs, and that adenoviral overexpression of APE1/Ref-1 inhibited Pi-induced calcification in VSMCs and in an ex vivo organ culture of a rat aorta. However, a redox mutant of APE1/Ref-1(C65A/C93A) did not reduce Pi-induced calcification in VSMCs, suggesting APE1/Ref-1-mediated redox function against vascular calcification. Additionally, APE1/Ref-1 overexpression inhibited Pi-induced intracellular and mitochondrial reactive oxygen species production, and APE1/Ref-1 overexpression resulted in decreased Pi-induced lactate dehydrogenase activity, pro-apoptotic Bax levels, and increased anti-apoptotic Bcl-2 protein levels. Furthermore, APE1/Ref-1 inhibited Pi-induced osteoblastic differentiation associated with alkaline phosphatase activity and inhibited Pi-exposure-induced loss of the smooth muscle phenotype. Our findings provided valuable insights into the redox function of APE1/Ref-1 in preventing Pi-induced VSMC calcification by inhibiting oxidative stress and osteoblastic differentiation, resulting in prevention of altered osteoblastic phenotypes in VSMCs., Competing Interests: The authors declare no conflicts of interest.

Enalapril and nifedipine are used as antihypertensive drugs; however, the therapeutic target molecules regulated by enalapril and nifedipine have yet to be fully identified. The aim of this study was to identify novel target genes that are specifically regulated by enalapril and nifedipine in tissues from spontaneously hypertensive rats (SHR) using DNA microarray analysis. We found that administration of SHR with enalapril and nifedipine differentially regulated 33 genes involved in the pathogenesis of cardiovascular diseases. Furthermore, we identified 16 genes that have not previously been implicated in cardiovascular diseases, including interleukin-24 (IL-24). Among them, exogenous administration of IL-24 attenuated the expression of vascular inflammation and hypertension-related genes induced by H2O2 treatment in mouse vascular smooth muscle (MOVAS) cells. This study provides valuable information for the development of novel antihypertensive drugs. In addition, the genes identified may be of use as biomarkers and therapeutic targets for cardiovascular diseases, including hypertension.