Circ_0061140 Contributes to Ovarian Cancer Progression by Targeting miR-761/LETM1 Signaling

Previous studies have suggested that circular RNAs (circRNAs) play important regulatory roles in cancer progression. Previous evidence exhibited the aberrant upregulation of circ_0061140 in ovarian cancer. However, the detailed role of circ_0061140 in ovarian cancer progression and its associated mechanism remain largely unknown and need further exploration. The expression of circ_0061140, microRNA-761 (miR-761) and leucine zipper and EF-hand containing transmembrane protein 1 (LETM1) was checked by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) or western blot. Cell Counting Kit-8 (CCK8), colony formation, 5-Ethynyl-2'-deoxyuridine (EdU), flow cytometry, wound healing, transwell, and tube formation assays were conducted to assess cell functions. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were performed to confirm the interaction between miR-761 and circ_0061140 or LETM1. Xenograft tumor model was established to analyze the role of circ_0061140 in tumor growth in vivo. Circ_0061140 expression was notably up-regulated in ovarian cancer tissues and cell lines. Circ_0061140 knockdown suppressed the proliferation, migration, invasion, and angiogenesis and triggered the apoptosis of ovarian cancer cells. Circ_0061140 directly interacted with miR-761, and circ_0061140 silencing-mediated anti-tumor effects were partly abolished by miR-761 knockdown in ovarian cancer cells. LETM1 was a direct target of miR-761, and LETM1 overexpression partly counteracted miR-761-induced anti-tumor effects. Circ_0061140 could up-regulate LETM1 expression by sponging miR-761. Circ_0061140 knockdown significantly suppressed xenograft tumor growth in vivo. Circ_0061140 aggravated ovarian cancer progression through miR-761-dependent regulation of LETM1.