Circular RNA profile of breast cancer brain metastasis: identification of potential biomarkers and therapeutic targets.

Aim: To explore the circular RNA (circRNA) profile of breast cancer brain metastasis (BCBM). Materials & methods: RNA-seq was performed to identify the circRNA expression profile of brain metastatic breast cancer cell line 231-BR, in comparison with its parental nonspecific metastatic cell line MDA-MB-231. Results: A total of 215 upregulated and 191 downregulated circRNAs were identified. The expression levels of ten randomly selected majorly altered circRNAs were re-examined by real-time quantitative PCR and agarose gel electrophoresis, and the following alterations were verified: upregulation of hsa_circ_0001944, hsa_circ_0001481, hsa_circ_0000646, hsa_circ_0001006 and hsa_circ_0000732, and down-regulation of hsa_circ_0001910, hsa_circ_0008285 and hsa_circ_0000002. CircRNA/miRNA analysis revealed that hsa_circ_0001944 may be involved in BCBM through sponging up miR-509 and interfering with its binding to the downstream targets. Conclusion: This study provides a leading and fundamental circRNA profile of BCBM.