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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.

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.

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