Circular RNA circFLNA inhibits the development of bladder carcinoma through microRNA miR-216a-3p/BTG2 axis

Abstract

Recent studies have shown that circular RNA circFLNA is abnormally expressed in a variety of malignant tumors, but its role and mechanism in bladder carcinoma (BCa) are still unclear. The present paper aims to contribute to research on the effects and mechanism of circFLNA on the malignant phenotype of BCa. In this study, the expressions of circFLNA, miR-216a-3p and BTG2 in BCa and BCa cells (EJ, T24, 5637, TCC-SUP) were detected by qRT-PCR. EdU staining, colony formation, Transwell assay, wound healing assays, and sphere formation assay were used to measure the cell proliferation, viability, invasion, migration, and cell stemness of BCa cells after circFLNA overexpression. In addition, the correlation existed between miR-216a-3p and circFLNA or BTG2 was confirmed by Dual-Luciferase Reporter assay and RNA pull-down. Western blot was utilized to determine the expression of BTG2, MMP2, epithelial-mesenchymal transition (EMT)-related proteins (vimentin, E-cadherin) and stem cell-specific proteins (CD34, OCT4, SOX2). Our study confirmed that downregulated circFLNA and BTG2 expression and upregulated miR-216a-3p were found in both BCa tissues and cell lines. Meanwhile, upregulated circFLNA inhibited proliferation, invasion and migration, EMT and stemness of BCa cells. MiR-216a-3p was a target gene of circFLNA and could target BTG2. Further analysis finally demonstrated that circFLNA sponged miR-216a-3p and indirectly promoted BTG2 expression, ultimately regulating proliferation, migration, invasion and EMT of BCa cells. In conclusion, circFLNA inhibits the malignant phenotype of BCa cells and their stemness through miR-216a-3p/BTG2, thus suppressing BCa progression.

Impact of SOX2 function and regulation on therapy resistance in bladder cancer

“…Circular RNA (circRNA) contain abundant miRNA binding sites and can act as miRNA sponges to regulate the posttranscriptional levels of their target genes (65) (Figure 2B). Lin et al (66) demonstrated that the expression of circRNA, which is circularized from exons 9-15 of the filament protein A (FLNA) gene (circFLNA), is downregulated in BC. The overexpression of circFLNA resulted in the significant downregulation of SOX2 expression.…”

“…Lin et al. ( 66 ) demonstrated that the expression of circRNA, which is circularized from exons 9–15 of the filament protein A ( FLNA ) gene (circFLNA), is downregulated in BC. The overexpression of circFLNA resulted in the significant downregulation of SOX2 expression.…”

“…The target gene of circFLNA was miR-216a-3p, and the overexpression of miR-216a-3p upregulated the expression of SOX2 . Their studies also revealed that circFLNA served as miRNA sponge and competitively adsorbed miR-216a-3p, thereby upregulating B-cell translocation gene 2 (BTG2) expression ( 66 ) ( Table 1 ). In their publication, SOX2 was positively regulated by miR-216a-3p, but the specific mechanism was not elucidated.…”

Pirfenidone attenuates cardiac hypertrophy against isoproterenol by inhibiting activation of the janus tyrosine kinase-2/signal transducer and activator of transcription 3 (JAK-2/STAT3) signaling pathway

“…The secondary antibody (1:2000, SolelyBio, Beijing, China) was subsequently added to be incubated for 90 min. Finally, the ECL reagent was added to expose the bands, which were further quantified with the Image J software [ 16 ].…”

Molecular mechanisms of microRNA-216a during tumor progression

“…BTG2 negatively mediates CCND1 and reduces the expression level of FoxM1 via suppressing the association of CCNB1/CDKs [ 147 ]. CircFLNA reduced the bladder tumor growth via miR-216a-3p/BTG2 axis [ 148 ].…”