Presentation Authors: Qiang Lu*, Xiao Yang, Wenbo Yuan, Rui Zhou, Jingzi Wang, Jie Han, Hao Yu, Hongcheng Lu, Pengchao Li, Jun Tao, Haiwei Yang, Min Gu, Nanjing, China, People's Republic of
Introduction: Circular RNAs (CircRNAs) have recently emerged as critical regulators of tumorigenesis and progression. Several studies on Cdr1as have demonstrated it to be a miRNA sponge in different tumors. However, the role of Cdr1as in bladder cancer chemosensitivity remains unclear.
Methods: Qualitative reverse transcription polymerase chain reaction was used to detect target 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 the cisplatin chemosensitivity of bladder cancer cells were determined using flow cytometry and a cell counting kit. Bioinformatic analysis was utilized to predict potential miRNA target sites on Cdr1as. Biotin-coupled miRNA capture, biotin-coupled probe pull-down assay, and RNA fluorescent in situ hybridization were performed to determine the interaction between Cdr1as and target miRNAs. Dual-luciferase reporter assay was also conducted to validate the target genes of miRNAs. The expression level of 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 and volume of tumors.
Results: Cdr1as induced the apoptosis and enhanced the cisplatin chemosensitivity of bladder cancer cells in vitro and in vivo. miR-1270 was highly expressed in bladder cancer tissues and cell lines and promoted cell proliferation, inhibited cell apoptosis, and reduced cisplatin chemosensitivity in T24 and EJ cells. 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.
Conclusions: 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 is expected to be a potential therapeutic target for bladder cancer patients.