CircKEAP1 serves as a ceRNA to suppress lung adenocarcinoma progression by activating KEAP1 signal pathway

Background: Circular RNAs (circRNAs) are widely expressed noncoding RNAs, and plays a key role in the biological function of competitive endogenous RNA (ceRNA) network in various human diseases, especially in cancer. However, the regulatory roles of circRNAs in lung adenocarcinoma (LUAD) remains largely unknown. Methods: The expression profiles of circRNAs in LUAD tissues and adjacent non-tumor tissues were analyzed by Agilent Arraystar Human CircRNA microarray. The level and prognostic values of circKEAP1 in tissues and cancer cell lines were determined by quantitative real-time PCR. Then, the effects of circKEAP1 on tumor growth were investigated by functional experiments in vitro and in vivo . Mechanistically, dual luciferase reporter assay, RNA pull-down and RNA immunoprecipitation experiments were performed to confirm the interaction between circKEAP1 and miR-141-3p in LUAD. Results: We found circKEAP1 was significantly downregulated in LUAD tissues, and repressed tumor growth both in vitro and in vivo . Mechanistically, circKEAP1 competitively binds to miR-141-3p and relive miR-141-3p repression for its target gene KEAP1, which activated the KEAP1/NRF2 signal pathway, and finally suppress the cell proliferation. Conclusions: Our findings suggest that circKEAP1 inhibits LUAD progression through circKEAP1/miR-141-3p/KEAP1 axis and it may serve as a new target for treatment of LUAD patients.