Effects of paricalcitol on hydrogen peroxide-induced oxidative damage in human umbilical vein endothelial cells through vitamin D receptor signaling

Abstract

Oxidative DNA damage is caused by the imbalance betweenreactive oxygen species (ROS) and the antioxidants in cells.Accumulation of DNA damage might lead to a variety of muta-tions and consequently to genomic instability. Paricalcitol is asynthetic vitamin D analog that shows similar physiologicalproperties with vitamin D, but has less hypercalcemic effects.Paricalcitol exerts most of its pleiotropic actions via binding tovitamin D receptor (VDR). The relation between vitamin D andnon-calcemic analogs such as paricalcitol with oxidative DNAdamage is noteworthy due to the high prevalence of vitamin defi-ciency and the importance of genomic instability. The aim of thisstudy is to investigate the dose-dependent effects of paricalcitolon the formation of ROS, levels of oxidatively induced DNAdamage and expressions of DNA repair enzyme APE1 and VDRin a model of hydrogen peroxide (H2O2)-generated oxidativestress in human umbilical vein endothelial cells (HUVEC). Threedoses (0.1–10–100 nM) of paricalcitol and 100 nM of ZK159222antagonist to evaluate the role of VDR were used in the study.The generation of ROS was assessed fluorometrically using theprobe dichlorofluorescein diacetate (DCFH-DA). APE1 andVDR gene expressions were analyzed by qPCR. Treatment of300lMH2O2significantly increased ROS as compared to con-trol (P<0.001). Paricalcitol pretreatments attenuated excessiveROS in HUVECs exposed to H2O2(P<0.05). Moreover, thiseffect was performed by VDR-mediated signaling. Treatment ofHUVEC with H2O2significantly decreased APE1 and VDRmRNA expressions (P<0.05). But, preincubation with differentdoses of paricalcitol did not have a significant effect on theexpressions of the APE1 and VDR. This study demonstrated thatparicalcitol might protect endothelial cells from H2O2-generatedoxidative stress. For further work, the levels of damaged DNAnucleosides will be analyzed using liquid chromatography-tandemmass spectrometry