Analysis of ceRNA network identifies prognostic circRNA biomarkers in bladder cancer

Bladder cancer remains a very challenging disease to treat with the high rates of recurrence and progression associated with current therapies. Although the association between bladder cancer pathology and circRNAs remains undetermined, circRNAs signatures may be useful as prognostic and predictive factors and clinical tools for assessing disease state and outcome. This study investigates if these circRNAs can be used as biomarkers for bladder cancer diagnosis. Differentially expressed RNAs in bladder cancer and normal bladder tissues were screened from GEO databases (GSE37815, GSE39093, GSE97239, and GSE92675) using bioinformatics method. The related volcanic maps and the interaction network maps of differentially expressed RNAs were drawn, and the mRNA-miRNA and miRNA-circRNA interactions were predicted to establish mRNA-miRNA-circRNA competitive endogenous RNA (ceRNA) network. The differential circRNAs related to prognosis of bladder cancer patients were screened based on the influence of miRNA interacting with the circRNA above on survival rate. The expression of miRNA (hsa-mir-214), circRNA (hsa_circ_0076704, hsa_circ_0081963, hsa_circ_0001361) in bladder cancer tissues, adjacent tissues, bladder cancer cells and normal bladder epithelial cells were validated by qRT-PCR. Kaplan Meier curve analysis confirmed the relationship between circRNA (hsa_circ_0076704) and overall survival and prognosis of bladder cancer patients. Through database screening and analysis, we found 19231 differentially expressed genes, 847 differentially expressed miRNAs, 7282 differentially expressed circRNAs. The establishment of ceRNA network consisted of 28 DERNAs (differentially- expressed RNAs), 12 Demi-RNAs and 12 DEcircRNAs. Further prognostic analysis showed that circRNA interacted miRNA hsa-miR-106b, hsa-miR-145 and hsa-miR-214 were associated with overall survival in patients with bladder cancer (p<0.05). Among them, hsa_circ_0076704, hsa_circ_0081963 and hsa_circ_0001361 are potential circRNAs related to the overall survival (OS) in bladder cancer and expressed in bladder cancer. The expression of hsa-mir-214 was contrary. Further Kaplan Meier survival analysis showed that hsa_circ_0076704 had significant prognostic value (p<0.05). In conclusion, hsa_circ_0076704 is independent prognostic factor for bladder cancer.