CircFN1 upregulation initiated oxidative stress-induced apoptosis and inhibition of proliferation and migration in trophoblasts via circFN1-miR-19a/b-3p-ATF2 ceRNA network

• CircFN1 was upregulated in PE patients’ serum and was associated with the diagnosis. • CircFN1 positively regulated oxidative stress and apoptosis in HTR-8/SV-neo cells. • Cell proliferation and migration were inhibited in circFN1-upregulated HTR-8/SV-neo cells. • CircFN1 was “miRNA sponge” for miR-19a/b-3p in regulation of ATF2. Recently, the etiopathogenesis of preeclampsia (PE) has been developed from the perspective of circular RNA, microRNA and their crosstalk in placental oxidative stress. Real-time quantitative PCR and western blotting detected expression of circular RNA-fibronectin 1 (circFN1; ID hsa_circ_0058152), microRNA (miR)-19a/b-3p and activating transcription factor 2 (ATF2). Receiver operating characteristic (ROC) curve analyzed the predictive value of circFN1. Oxidative stress, apoptosis, proliferation, and migration were measured using superoxide dismutase (SOD) and malonaldehyde (MDA) assay kits, Annexin V/Prodium iodide and western blotting methods, MTS and EdU assays, and scratch wound assay, respectively. Target relationships were retrieved by miRNA target prediction software and confirmed by dual-luciferase reporter assay, RNA immunoprecipitation and RNA pull-down. Expression of circFN1 was upregulated in the serum of PE pregnancies, and the area under the ROC curve of serum circFN1 was 0.7826 (95% confidence interval: 0.6495–0.9157; sensitivity 86.96%; specificity 56%). Functionally, its upregulation decreased SOD activity, cell viability , EdU incorporation, migration rate, and Bcl-2 expression in human trophoblast HTR-8/SV-neo cells, but meanwhile increased MDA level, apoptosis rate, and Bax and cleaved-caspase3 expression. Moreover, its downregulation played the opposite effects in HTR-8/SV-neo cells. Mechanistically, circFN1 functioned as “miRNA sponge” for miR-19a/b-3p and modulated the latter’s target gene ATF2. There were feedback effects of miR-19a/b-3p restorations and ATF2 depletion on circFN1 actions in HTR-8/SV-neo cells. Oxidative injury-mediated placental trophoblast dysfunction in PE was through competing endogenous RNA (ceRNA) mechanism of CircFN1-miR-19a/b-3p-ATF2 axes.