Andrographolide sodium bisulfate-induced apoptosis and autophagy in human proximal tubular endothelial cells is a ROS-mediated pathway

•We firstly verified that andrographolide sodium bisulfate (ASB) could suppress HK-2 cell growth and proliferation within the concentration ranging from 7 mmol/L to 57 mmol/L.•We firstly found that ASB could induce ROS generation abundantly in HK-2 cells, activate JNK signaling pathway, and further induce cell apoptosis via mitochondria dependent-caspase pathway.•Interestingly, ASB could induce HK-2 cell autophagy as well in the concentration of 14 and 29 mmol/L respectively, which maybe a result of Beclin-1 upregulating.•Our findings provided a novel pathway for the study of mechanism underlying ASB-induced nephrotoxicity.

Background and aimsThe nephrotoxic mechanisms of andrographolide sodium bisulfate (ASB) remain largely unknown. This study attempted to explore the mechanism of ASB-induced nephrotoxicity using human proximal tubular endothelial cells (HK-2).MethodsFor this study HK-2 cells were treated with rising concentrations of ASB. Their survival rate was detected using MTT assay and ultrastructure was observed with electron microscopy. l-Lactate dehydrogenase (LDH) assay was followed by examination of mitochondrial membrane potential (MMP). Reactive oxygen species (ROS) was detected using different methods and apoptosis/autophage related proteins were detected using immunoblotting.ResultsWe found that ASB inhibited HK-2 cell proliferation and decreased cell survival rate in a time and dose-dependent manner (P < 0.05, P < 0.01, respectively). With increasing ASB concentration, cell structure was variably damaged and evidence of apoptosis and autophagy were observed. MMP gradually decreased and ROS was induced. The expression of JNK and Beclin-1 increased and activation of the JNK signaling pathway were seen. Apoptosis was induced via the mitochondrial-dependent caspase-3 and caspase-9 pathway, and autophagy related protein Beclin-1 was enhanced by ASB.ConclusionThe data show that ASB induces high levels of ROS generation in HK-2 cells and activates JNK signaling. Furthermore, ASB induces cell apoptosis via the caspase-dependent mitochondrial pathway, and induces cellular autophagy, in part by enhancing Beclin-1 protein expression.

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