Circular RNA TAF4B Promotes Bladder Cancer Progression by Sponging miR-1298-5p and Regulating TGFA Expression

Abstract Background: Bladder cancer (Bca) is the most common malignant tumor of urinary system. Circular RNAs (circRNAs) have been recognized as a key regulator in tumorigenesis. However, the molecular mechanisms underlying circular RNAs involved in the progression of Bca remain largely unknown. Methods: We detected the expresion level of Circular RNA TAF4B (circTAF4B) by qRT-PCR. Cell proliferative activity was evaluated by CCK-8 and colony formation assays. Wound healing assay and transwell migration assay were performed to measure cell migration capability. Transwell invasion assay was applied to assess cell metastasis. Moreover, we used qRT-PCR and western blotting assay to detect cell EMT ability. In addition, the target microRNA of circ TAF4B and the downstream target gene were predicted by a bioinformatics analysis, and the interactions were verified by RNA pull-down assay, Nuclear/cytoplasmic fractionation and dual-luciferase reporter assays. A mouse xenograft model was developed and used to analyze the effects of circTAF4B in the tumorigenesis of bladder cancer in vivo. Results: Here, we identified a novel circular RNA, circTAF4B, which significantly up-regulated in BC and correlated with the clinical prognosis. And down-regulated circTAF4B abolished the growth, metastasis and epithelial-mesenchymal transition (EMT) in BC cells. Mechanistically, we found that circTAF4B facilitated the expression of TGFA through sponging miR-1298-5p, furthermore enhancing the development of bladder cancer cells. Moreover, circTAF4B enhanced the proliferation and EMT of BC cells in vivo Conclusion: In summary, our study demonstrated that circTAF4B, as a miRNA sponge, played a carcinogenic role in the growth, metastasis, and EMT of BC by regulating the miR-1298-5p/TGFA axis. Thus, circTAF4B may contribute as a diagnostic and therapeutic target for bladder cancer.