CircHSPG2 absence weakens hypoxia-induced dysfunction in cardiomyocytes by targeting the miR-25-3p/PAWR axis.

Background: Circular RNAs (circRNAs) are important regulators in human cardiovascular diseases. Here, we investigated the role of circRNA heparan sulfate proteoglycan 2 (circHSPG2) in hypoxia-induced myocardial infarction (MI) and its associated mechanism. Methods: Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot assay were conducted to examine RNA and protein expression. Cell viability was analyzed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) assay. Cell proliferation was assessed by 5-Ethynyl-2'-deoxyuridine (EdU) assay and colony formation assay. Flow cytometry (FCM) analysis was carried out to analyze the apoptosis of AC-16 cells. Lactate dehydrogenase (LDH) assay was implemented to assess cell death. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were performed to verify the target relationship between microRNA-25-3p (miR-25-3p) and circHSPG2 or pro-apoptotic WT1 regulator (PAWR). Results: Hypoxia treatment up-regulated the expression of circHSPG2 in AC-16 cells. Hypoxia exposure reduced the viability, suppressed the proliferation and induced the apoptosis of AC-16 cells, and these effects were diminished by the silence of circHSPG2. CircHSPG2 acted as a molecular sponge for miR-25-3p. CircHSPG2 absence-mediated effects on hypoxia-induced AC-16 cells were largely reversed by anti-miR-25-3p. miR-25-3p bound to the 3' untranslated region (3'UTR) of PAWR. PAWR overexpression largely counteracted miR-25-3p-mediated effects on hypoxia-induced AC-16 cells. CircHSPG2 positively regulated the expression of PAWR by acting as miR-25-3p sponge in AC-16 cells. Conclusions: CircHSPG2 silencing protected AC-16 cells against hypoxia-induced dysfunction by targeting miR-25-3p/PAWR axis.