CircRNA‑CER mediates malignant progression of breast cancer through targeting the miR‑136/MMP13 axis

Abstract

Chondrocyte extracellular matrix-related circular RNAs (circRNA-CER) have been demonstrated to be involved in various diseases. However, its role in the development of human breast cancer is not clearly understood. The aims of the presentstudyweretoassesscircRNA-CERexpressioninpaired cancer tissue and adjacent non-tumor tissue from 24 patients with breast cancer, and to explore the roles and mechanisms by which circRNA-CER mediates the malignant progression of breast cancer cells. The results revealed that circRNA-CER and matrix metalloproteinase 13 (MMP13) were upregulated, whereas miR-136 was downregulated in breast cancer tissues compared with adjacent non-tumor tissues. In vitro silencing of circRNA-CER using small interfering RNA (siRNA) had inhibitory effects on MCF-7 breast cancer cell proliferation and migration, and similar results were obtained following overexpression of microRNA (miR)-136 in MCF-7 cells by transfection with miR-136 mimics. The subsequent mechanistic study revealed that the expression levels of MMP13 were significantly lower in MCF‑7 cells following transfection with miR-136 mimics, and silencing of circRNA-CER enhanced miR-136 and decreased MMP13 expression levels. Furthermore, silencing of miR-136 by transfection with miR-136 inhibitors resulted in an increase in MCF-7 cell proliferation and migration. miR-136 inhibitor-derived biological effects were reversed by co-transfection of cells with miR-136 inhibitors and circRNA-CER siRNA. Taken together, the present results suggested that circRNA-CER may serve an important role in the progression of breast cancer by regulating the activity of the miR-136/MMP13 axis, and may be a potential biomarker for the prediction and treatment of breast cancer.