Microarray expression profile analysis of circular RNAs and their potential regulatory role in bladder carcinoma

Dysregulated circular RNAs (circRNAs) often contribute to the occurrence and development of various tumors; however, the function and mechanism of circRNAs are largely unknown in human bladder cancer (BC). In the present study, dysregulated circRNAs between BC and adjacent non-neoplastic bladder tissues were analyzed by circRNA microarray. We randomly selected 10 upregulated and five downregulated circRNAs for validation by quantitative real-time PCR. Bioinformatics analysis was further conducted to investigate the potential function of these differentially expressed circRNAs, with the differential expression of hsa_circRNA_100876, mir-136-5p, and mRNA-chromobox 4 (CBX4) subsequently verified. A total of 512 differentially expressed circRNAs were identified after scanning and normalization (340 upregulated and 172 downregulated circRNAs), with pathway and Gene Ontology analyses revealing their association with multiple significant cancer pathways. Construction of a circRNA-microRNA-mRNA network suggested additional potential roles of these circRNAs. The expression of hsa_circRNA_100876 and CBX4 was significantly negatively correlated with the expression of miR-136-5p. Additionally, hsa_circRNA_100876 was highly positively correlated with CBX4 expression. The results revealed that hsa_circRNA_100876 inhibition suppressed BC cell proliferation and it was associated with advanced T stage and lymphatic metastasis, and poor overall survival of BC patients. In conclusion, these differentially expressed circRNAs offer novel insights into potential biological markers or new therapeutic targets for the treatment of BC. Furthermore, hsa_circRNA_100876 may increase the expression of CBX4 by competing with miR-136-5p, ultimately promoting the malignant biological behavior of BC. Aberrantly expressed hsa_circRNA_100876 could be used as a potential non-invasive biomarker for the early detection and screening of BC.