Comprehensive circular RNA profiling reveals the regulatory role of circ_100242/miR-145 pathway in bladder cancer.

Bladder cancer is a common genitourinary carcinoma with high morbidity and mortality rates. Circular RNAs (circRNAs), which are a type of single-stranded RNAs, have been characterized as stable, conserved and tissue-specific molecules in mammalian cells. The present study explored the circRNA expression profile in four bladder cancer tissues and matched normal samples by using microarray analysis. Furthermore, bioinformatics analyses were performed to investigate the potential function of dysregulated circRNAs in bladder cancer. The results demonstrated that 89 circRNAs were downregulated and 210 circRNAs were upregulated in bladder cancer tissues. The results from RT-qPCR demonstrated that hsa_circ_100241, hsa_circ_100242 and hsa_circ_101303 were markedly upregulated whereas hsa_circ_104510 was significantly downregulated in bladder cancer tissues compared with normal tissue. Following circRNA/microRNA (miRNA) interaction network generation via Cytoscape, it was demonstrated that hsa_circ_100242 contained a miRNA response element for miR-145-5p, which is a tumor suppressor in bladder carcinoma. In addition, results from the Kyoto Encyclopedia of Genes and Genomes analysis showed that the MAPK signaling pathway was the most significant pathway of the differentially expressed circRNAs in bladder cancer tissues. In conclusion, the present study demonstrated that circRNAs were dysregulated in bladder cancer tissues compared with matched normal samples. Pathway analysis was also performed to predict the binding of miRNAs to the dysregulated circRNAs. The results revealed that hsa_circ_100242 may be involved in bladder cancer initiation and progression by sponging miR-145. These findings may provide further insights into the functional and therapeutic roles of circRNAs in bladder cancer.