Comprehensive circular RNA profiling reveals the regulatory role of the circRNA-000911/miR-449a pathway in breast carcinogenesis

Circular RNAs (circRNAs) are key regulators in the development and progression of human cancers; however their roles in breast tumorigenesis are not yet well understood. Thus, the present study aimed to investigate the expression profiles and potential modulatory effects of circRNAs on breast carcinogenesis. A human circRNA microarray analysis was performed to screen for abnormally expressed circRNAs in breast cancer tissue and circRNA-000911 was identified as a circRNA which was significantly downregulated in breast cancer cells. Mechanistic investigations suggested that the enhanced expression of circRNA-000911 suppressed cell proliferation, migration and invasion, and promoted the apoptosis of breast cancer cells. By using a biotin-labeled circRNA-000911 probe to perform RNA precipitation in breast cancer cells, we identified miR-449a as the circRNA-000911-associated microRNA. Gain- and loss-of-function assays indicated that miR-449a antagonized circRNA-000911 to regulate breast cancer progression. Subsequently, Notch1 was identified as the functional target of miR-449a, and the overexpression of circRNA-000911 in breast cancer elevated Notch1 expression. Furthermore, Cignal Signal Transduction Reporter Array and western blot analysis identified nuclear factor-B (NF-B) signaling as a functional target of the circRNA-000911/miR-449a pathway. On the whole, our findings indicate that circRNA-000911 plays an anti-oncogenic role in breast cancer and may thus serve as a promising therapeutic target for patients with breast cancer. Therefore, the overexpression of circRNA-000911 may provide a future direction which may aid in the development of a novel treatment strategy for breast cancer.