Circ_HECW2 functions as a miR-30e-5p sponge to regulate LPS-induced endothelial-mesenchymal transition by mediating NEGR1 expression

Endothelial-mesenchymal transition (EndoMT) plays a critical role in the dysfunction of the blood-brain barrier (BBB). Circular RNAs (circRNAs) function as crucial regulatory factors in EndoMT. Nevertheless, the underlying mechanisms of circRNA HECW2 (circ_HECW2, hsa_circ_0057583) in lipopolysaccharide (LPS)-induced EndoMT remain largely unclear. The levels of circ_HECW2, miR-30e-5p and neuronal growth regulator 1 (NEGR1) were detected by quantitative real-time polymerase chain reaction (qRT-PCR) or western blot. Ribonuclease (RNase) R and Actinomycin D assays were performed to validate the stability of circ_HECW2. Cell colony formation, proliferation and apoptosis were tested by a standard colony formation assay, the 3-(4,5-dimethylthiazol-2yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay and flow cytometry, respectively. Targeted relationships among circ_HECW2, miR-30e-5p and NEGR1 were verified by a dual-luciferase reporter assay. Our data indicated that LPS increased circ_HECW2 expression and reduced miR-30e-5p expression in human brain microvascular endothelial cells (HBMECs). Circ_HECW2 silencing promoted cell proliferation and suppressed cell apoptosis and EndoMT in LPS-treated HBMECs. Mechanistically, circ_HECW2 directly interacted with miR-30e-5p by binding to miR-30e-5p. MiR-30e-5p was a functional mediator of circ_HECW2 in regulating LPS-induced cell EndoMT. Furthermore, Circ_HECW2 regulated NEGR1 expression through functioning as a miR-30e-5p sponge. Moreover, miR-30e-5p overexpression repressed the EndoMT of LPS-treated HBMECs by targeting NEGR1. Collectively, our current study demonstrated that circ_HECW2 silencing suppressed LPS-triggered HBMEC EndoMT at least in part through the regulation of the miR-30e-5p/NEGR1 axis, illuminating a promising strategy for EndoMT inhibition.