Circular RNAs (circRNAs) have recently emerged as essential regulators in carcinogenesis and cancer progression. Previous studies have shown that Cdr1as functions as a microRNA (miRNA) sponge in various cancer types. However, the role of Cdr1as in cisplatin chemosensitivity in bladder cancer remains unclear. Here, we used real-time PCR to examine miRNA and gene expression in bladder cancer tissues and cell lines. The abilities of Cdr1as and its downstream regulatory molecules to induce apoptosis and promote cisplatin-induced chemosensitivity of bladder cancer cells were determined by flow cytometry and cell counting kit. Bioinformatic analysis was utilized to predict potential miRNA target sites, and biotin-coupled miRNA capture, biotin-coupled probe pull-down assay, and RNA fluorescent in situ hybridization were used to study the interaction between Cdr1as and target miRNAs. Dual-luciferase reporter assay was also used to validate the target genes of miRNAs. The expression level of apoptotic protease-activating factor 1 (APAF1) in bladder cancer cells was identified via western blot. Finally, the sensitivity of Cdr1as to cisplatin chemotherapy in nude mice xenografts was evaluated in terms of the size, volume of tumors, and the survival of mice. We report that Cdr1as induced the apoptosis and enhanced the cisplatin chemosensitivity of bladder cancer cells both in vitro and in vivo. Silencing of APAF1 reduced the sensitivity of bladder cancer cells to cisplatin chemotherapy. Furthermore, Cdr1as could directly sponge miR-1270 and abolish its effect on APAF1. Our study verified that Cdr1as exerts a cisplatin-chemosensitization effect on bladder cancer cells through the Cdr1as/miR-1270/APAF1 axis. This newly identified axis may be a potential therapeutic target for bladder cancer patients.

中文翻译：

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环状RNA Cdr1as通过miR-1270抑制作用上调APAF1表达，从而使膀胱癌对顺铂敏感。

环状RNA（circRNA）最近已成为癌变和癌症进展中的重要调节剂。先前的研究表明，Cdr1as在各种癌症类型中均起着microRNA（miRNA）海绵的作用。但是，尚不清楚Cdr1as在膀胱癌中对顺铂化学敏感性的作用。在这里，我们使用实时PCR检测膀胱癌组织和细胞系中的miRNA和基因表达。通过流式细胞仪和细胞计数试剂盒测定了Cdr1as及其下游调控分子诱导凋亡和促进顺铂诱导的膀胱癌细胞化学敏感性的能力。利用生物信息学分析来预测潜在的miRNA靶位点，并进行生物素偶联的miRNA捕获，生物素偶联的探针下拉测定，用RNA荧光原位杂交技术研究Cdr1as与靶miRNA之间的相互作用。双荧光素酶报告基因测定法也用于验证miRNA的靶基因。通过蛋白质印迹法鉴定了凋亡蛋白酶激活因子1（APAF1）在膀胱癌细胞中的表达水平。最后，根据肿瘤的大小，体积和小鼠的存活率评估了Cdr1as对裸鼠异种移植物中顺铂化疗的敏感性。我们报告Cdr1as诱导凋亡，并在体外和体内增强膀胱癌细胞的顺铂化学敏感性。沉默APAF1可降低膀胱癌细胞对顺铂化疗的敏感性。此外，Cdr1as可以直接使miR-1270海绵化，并取消其对APAF1的作用。我们的研究证实，Cdr1as通过Cdr1as / miR-1270 / APAF1轴对膀胱癌细胞产生顺铂化学增敏作用。这个新确定的轴可能是膀胱癌患者的潜在治疗靶标。