H.-S. Kang

Interleukin-24 attenuates β-glycerophosphate-induced calcification of vascular smooth muscle cells by inhibiting apoptosis, the expression of calcification and osteoblastic markers, and the Wnt/β-catenin pathway.

Vascular calcification is a hallmark of cardiovascular disease. Interleukin-24 (IL-24) has been known to suppress tumor progression in a variety of human cancers. However, the role of IL-24 in the pathophysiology of diseases other than cancer is unclear. We investigated the role of IL-24 in vascular calcification. IL-24 was applied to a β-glycerophosphate (β-GP)-induced rat vascular smooth muscle cell (VSMC) calcification model. In this study, IL-24 significantly inhibited β-GP-induced VSMC calcification, as determined by von Kossa staining and calcium content. The inhibitory effect of IL-24 on VSMC calcification was due to the suppression of β-GP-induced apoptosis and expression of calcification and osteoblastic markers. In addition, IL-24 abrogated β-GP-induced activation of the Wnt/β-catenin pathway, which plays a key role in the pathogenesis of vascular calcification. The specificity of IL-24 for the inhibition of VSMC calcification was confirmed by using a neutralizing antibody to IL-24. Our results suggest that IL-24 inhibits β-GP-induced VSMC calcification by inhibiting apoptosis, the expression of calcification and osteoblastic markers, and the Wnt/ β-catenin pathway. Our study may provide a novel mechanism of action of IL-24 in cardiovascular disease and indicates that IL-24 is a potential therapeutic agent in VSMC calcification.

Interleukin-24 suppresses the growth of vascular smooth muscle cells by inhibiting H(2)O(2)-induced reactive oxygen species production.

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.