Downregulation of hsa_circ_0006220 and its correlation with clinicopathological factors in human breast cancer

Background: Circular ribonucleic acids (circRNAs) are highly stable and conserved forms of RNAs present in all eukaryotes. They can modulate the expression of genes by sponging specific micro RNAs (miRNAs), thereby affecting various disease processes. However, their expression pattern in human breast cancer has not been elucidated. Methods: In this study, differentially expressed circRNAs in breast cancer tissues and paired noncancerous tissues were analyzed using an Arraystar Human circRNA Microarray, and hsa_circ_0006220 was selected for its 27-fold downregulation in breast cancer tissues. Its expression was also verified in 50 breast cancer and paired noncancerous tissues using real-time polymerase chain reaction (RT-PCR). An analysis of the expression of hsa_circ_ 0006220 and the clinicopathological factors in breast cancer was conducted. A receiver operating characteristic (ROC) curve of hsa_circ_0006220 was constructed. The interaction between hsa_circ_0006220 and five possible target miRNAs was predicted, and their expression were verified when overexpressing hsa_circ_0006220 by RT-PCR. Results: Hsa_circ_0006220 was found to be significantly downregulated in breast cancer tissues compared to the paired noncancerous tissues by microarray and RT-PCR. The expression of hsa_circ_0006220 was significantly inversely correlated with histological type (P=0.0028) and lymph node metastasis (P=0.0341). The area under the ROC curve (AUC) was 0.706. Five miRNAs that might be sponged by hsa_circ_0006220 were predicted. MiR-197-5p was significantly downregulated after overexpression of hsa_circ_0006220. Conclusions: Our results indicated that hsa_circ_0006220 may play a role in human breast cancer and might be a potential tumor marker for breast cancer screening.