A Novel Circular RNA circPTCD3 Promotes Breast Cancer Progression Through Sponging miR-198

INTRODUCTION: Circular RNAs (circRNAs), a new type of non-coding RNA, have been demonstrated to play critical roles in the progression of various of malignant cancers. However, the function of circRNAs in breast cancer is not clearly understood. METHODS: qPCR was used to evaluate the gene expression. Function studies including MTT, transwell, wound healing and colony formation assay were performed to evaluate the function of circPTCD3 in breast cancer. Luciferase and RNA pull-down assays were used to verify the interaction between circPTCD3 and miR-198. The xenograft model was established to evaluate the function of circPTCD3 in vivo. RESULTS: In the present study, we identified a novel circRNA termed as circPTCD3 which was indicated to be significantly up-regulated in breast cancer tissues and cell lines. The results revealed that ectopic expression of circPTCD3 promoted the cell proliferation, migration and colony formation ability of breast cancer cells. Constantly, silencing of circPTCD3 inhibited those of breast cancer cells. Furthermore, we identified that circPTCD3 was able to target miR-198 in breast cancer cell. miR-198 has the function of inhibiting proliferation and migration of breast cancer cells which can be reversed by circPTCD3. CONCLUSION: Taken together, our findings for the first time identified a novel circRNA (circPTCD3) and revealed its oncogenic role in breast cancer. Mechanically, we reported that circPTCD3 served as a competing endogenous RNA (ceRNA) to sponge miR-198. These findings provide insights into breast cancer progression and also potential new targets for diagnosis or treatment of breast cancer.