IOX1, a JMJD2A inhibitor, suppresses the proliferation and migration of vascular smooth muscle cells induced by angiotensin II by regulating the expression of cell cycle-related proteins

The epigenetic modification of vascular smooth muscle cell (VSMC) phenotypic switching, proliferation, migration, Apoptosis and extracellular matrix synthesis is known to occur in atherosclerosis. The aim of the present study was to investigate the effects of IOX1, a Jumonji domain-containing 2A (JMJD2A) inhibitor, on regulation of the cell cycle in angiotensin II (Ang II)-stimulated VSMCs and to elucidate the possible mechanisms involved. The proliferation and migration of the Ang II-stimulated VSMCs in the presence or absence of IOX1 were evaluated in vitro. Flow cytometric analysis was used to determine the effects of IOX1 on cell cycle progression. RT-qPCR and western blot analysis were carried out to measure the expression levels of cell cycle-related genes. The trimethylation of histone H3 lysine 9 (H3K9me3) at the promoters of these genes was detected by chromatin immunoprecipitation (ChIP) assay. We confirmed that the JMJD2A levels were increased, whereas the H3K9me3 levels were decreased in the Ang II-stimulated VSMCs. The inhibition of JMJD2A by IOX1 suppressed the Ang II-induced cell proliferation, migration and cell cycle progression by inhibiting cyclin D1 expression and increasing p21 expression. The underlying mechanisms were related to the restoration of the H3K9me3 levels at the promoters of these genes. In conclusion, the findings of our study indicate that IOX1 exerts its anti-proliferative and anti-migratory effects by regulating the expression of the cell cycle-related proteins, cyclin D1 and p21.