BACKGROUND Increasing evidences indicate that circular RNAs exert critical function in regulating bladder cancer progression. However, the expressive patterns and roles of circular RNAs in bladder cancer remain less investigated. METHODS circRIP2 was identified and evaluated by RNA-sequencing and qPCR; in vitro effects of circRIP2 were determined by CCK8, clone forming, wound healing and trans-well assays; while mice subcutaneous tumor model was designed for in vivo analysis. Western blot, RNA pulldown assay, miRNA capture and dual luciferase assessment were applied for mechanistic studies. RESULTS circRIP2 was identified as a conserved and dramatically repressed circular RNA in bladder cancer. Patients that displayed higher circRIP2 expression negatively associate with the grade, stage, metastasis as well as outcome of bladder cancer. In vitro and in vivo studies suggest that circRIP2 enables to promote bladder cancer progression via inducing EMT. Regarding the mechanism, we performed RNA-sequencing analysis, RNA pulldown with biotin-labeled circRIP2-specific probe, dual luciferase reporter assay. It was found that circRIP2 enables to sponge miR-1305 to elevate Tgf-β2 in bladder cancer, and inducing EMT via Tgf-β2/smad3 pathway. Blocking Tgf-β2 in bladder cancer deprives circRIP2 induced cancer progression and EMT. CONCLUSIONS Taken together, our study provides the first evidence that circRIP2 expresses differentially in bladder cancer and negatively along with the cancer progression; effective circRIP2 activity accelerates bladder cancer progression via inducing EMT by activating miR-1305/Tgf-β2/smad3 pathway. The research implies that circRIP2 might be a potential biomarker and therapeutic target for bladder cancer patients.

中文翻译：

---

circRIP2通过miR-1305 /Tgf-β2/ smad3途径加速膀胱癌的进展。

背景技术越来越多的证据表明，环状RNA在调节膀胱癌的进展中起关键作用。但是，环形RNA在膀胱癌中的表达模式和作用仍待研究。方法通过RNA测序和qPCR鉴定和评估circRIP2。通过CCK8，克隆形成，伤口愈合和trans-well测定来确定circRIP2的体外作用。设计小鼠皮下肿瘤模型进行体内分析。蛋白质印迹，RNA下拉测定，miRNA捕获和双重荧光素酶评估被用于机理研究。结果circRIP2被鉴定为膀胱癌中一种保守且显着抑制的环状RNA。显示较高circRIP2表达的患者与膀胱癌的等级，分期，转移和结局负相关。体外和体内研究表明，circRIP2能够通过诱导EMT促进膀胱癌的进展。关于机制，我们进行了RNA测序分析，用生物素标记的circRIP2特异性探针进行RNA下拉，双重荧光素酶报告基因分析。发现circRIP2可使海绵状miR-1305升高膀胱癌中的Tgf-β2，并通过Tgf-β2/ smad3途径诱导EMT。在膀胱癌中阻断Tgf-β2使circRIP2诱导的癌症进展和EMT丧失。结论综上所述，我们的研究提供了第一个证据，证明circRIP2在膀胱癌中差异表达，并且随着癌症的进展而呈阴性表达。有效的circRIP2活性通过激活miR-1305 /Tgf-β2/ smad3途径诱导EMT来加速膀胱癌的发展。