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 H(2)O(2)-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 H(2)O(2) by inducing a cell cycle arrest at the G(0)/G(1) 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 H(2)O(2). Interestingly, IL-24 attenuated the H(2)O(2)-induced ROS production by reducing the mitochondrial H(2)O(2) production and enhancing the expression of antioxidant enzymes. We also showed that the ability of H(2)O(2) 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 H(2)O(2)-induced ROS production through the regulation of mitochondrial ROS production and expression of antioxidant enzymes.