CircRNF13 regulates the invasion and metastasis in lung adenocarcinoma by targeting miR-93-5p

Circular RNAs (circRNAs) are a group of non-protein-coding RNAs that are generated from back-splicing. Recent evidence indicates that circRNAs play important roles in tissue development, gene regulation, and carcinogenesis. It was recently demonstrated that circular RNAs can function as sponges for miRNAs. In our study, the clinical implications of circRNF13 were assessed in 50 pathologically diagnosed lung adenocarcinoma samples and their paired peripheral normal lung tissues by using quantitative polymerase chain reaction. We validated that circRNF13 was almost 2.98-fold down-regulated in cancer tissues. The expression level of circRNF13 was significantly negatively correlated with TNM staging and lymph node metastasis. In vitro experiments indicated that circRNF13 repressed the invasion and metastasis of lung adenocarcinoma cell lines. Cell fraction analyses and fluorescence in situ hybridization detected that circRNF13 was mostly located in the cytoplasm. Bioinformatic analyses and RIP experiments revealed that circRNF13 could interact with Ago2, an RNA binding protein, and could function as sponge for miR-93-5p. Our data suggest that circRNF13 represents a potential novel biomarker and a therapeutic target of lung adenocarcinoma.