Circular RNA circRHOBTB3 inhibits ovarian cancer progression through PI3K/AKT signaling pathway

BACKGROUND: Circular RNAs (circRNAs) have emerged as significant regulators in human cancers. We aimed to explore the functional role of circular RNA RHOBTB3 (circRHOBTB3) in ovarian cancer. METHODS: The expression of circRHOBTB3 was detected by real-time quantitative PCR (RT-qPCR). Then, the localization of circRHOBTB3 in ovarian cancer cells was identified by cell fractionation assay. Cell proliferation, migration and invasion were measured by cell counting kit -8 (CCK-8), transwell migration and invasion assays, respectively. The protein expression of N-cadherin, vimentin and E-cadherin was measured by western blot. And the glucose consumption and lactate production were detected by a glucose colorimetric assay kit and a lactic acid production detection kit, respectively. The involvement mRNA and protein expression of glucose transporter 1 (GLUT1), hexokinase-2 (HK2) and lactate dehydrogenase A (LDHA) were determined by RT-qPCR and western blot, respectively. Besides, lentivectors for short hairpin RNA (shRNA) against circRHOBTB3 (sh-circRHOBTB3) or pcDNA-circRHOBTB3 were used to downregulate or upregulate circRHOBTB3 expression in an animal tumor model. The protein expression of phosphoinositide 3-kinase (PI3K), phospho-PI3K (p-PI3K), protein kinase B (AKT), phospho-AKT (p-AKT), mammalian target of rapamycin (mTOR) and phospho-mTOR (p-mTOR) was examined by western blot. The activator (740Y -P) and inhibitor (LY294002) of PI3K/AKT pathway were used to evaluate the contribution of PI3K/AKT. CircRHOBTB3 was downregulated in ovarian cancer tissues and cells. RESULTS: Functionally, circRHOBTB3 overexpression could markedly suppress cell proliferation, metastasis, and glycolysis, whereas the opposite results could be observed in the deletion of circRHOBTB3. Additionally, xenograft experiment also identified the above results. Finally, we observed that circRHOBTB3 inhibited the progression of ovarian cancer via inactivating PI3K/AKT signaling pathway. CONCLUSIONS: CircRHOBTB3 exerted a suppressor role and inhibited the tumorigenesis by inactivating PI3K/AKT pathway in ovarian cancer.