CircFAM188A Regulates Autophagy via miR-670-3p and ULK1 in Epithelial Ovarian Carcinoma.

CircRNAs and autophagy are closely involved in the physiological and pathological processes of ovarian cancer; however, their exact mechanisms are still undetermined. This investigation aimed to elucidate the function and associated pathways of circFAM188A, which modulates proliferation, autophagy, and invasion in ovarian cancer (EOC). The expression of circFAM188A in the tissues of EOC patients was assessed via RT-PCR. To elucidate proliferation, invasion, and autophagy in the tumor cells, Transwell, 5-ethynyl-2'-deoxyuridine (EdU), and mRFP-GFP-LC3 reporter assays were conducted. The binding sites between circ-FAM188A and the miR-670-3p, miR-670-3p and YY1 were predicted using bioinformatics and verified by dual-luciferase reporter assays. Pulldown assays demonstrated binding between ULK1 and circ-FAM188A. ULK1 was found to be crucial in the initial stage of autophagy. Moreover, an in vivo xenograft model was established by subcutaneous injection of nude mice with EOC cells. Expression of circ-FAM188A was increased in EOC tissues relative to normal ovarian tissues and circ-FAM188A overexpression promoted proliferation, invasion, and autophagy; these effects were reversed by circ-FAM188A silencing. miR-670-3p and circ-FAM188A co-localized in the cytoplasm. circ-FAM188A enhanced YY1 expression by sponging miR-670-3p and was also shown to interact with ULK1. It is thus suggested that circ-FAM188A modulates autophagy by sponging miR-670-3p as well as interacting with ULK1.

Yong M ，Zeng Y ，Yao Y ，Yang M ，Tang F ，Zhu H ，Hu J ... -  《Cancer Reports》

Circ-PGAM1 promotes malignant progression of epithelial ovarian cancer through regulation of the miR-542-3p/CDC5L/PEAK1 pathway.

Epithelial ovarian cancer (EOC) is the most common ovarian malignant cancer. Circular RNA is a type of endogenous noncoding RNA and is considered as a novel regulatory molecule in the development and progression of tumors. This study investigated the expression and functions of a circular RNA, circular-phosphoglycerate mutase 1 (circ-PGAM1), in EOC tissues and cells. The expression of circ-PGAM1 and miR-542-3p in EOC was analyzed using quantitative RT-PCR. Immunohistochemistry and western blot were performed to confirm the localization and expression of cell division cycle 5-like (CDC5L) and pseudopodium enriched atypical kinase 1 (PEAK1) in EOC tissues. Cell lines (CAOV3 and OVCAR3) overexpressing or silencingcirc-PGAM1 and miR-542-3p were established to explore the functions of circ-PGAM1 and miR-542-3p in ovarian cancer cells. Furthermore, dual-luciferase reporter assay was performed to study the interactions between circ-PGAM1 and miR-542-3p and between miR-542-3p and CDC5L. CCK-8, transwell, and flow cytometry were used to study the effect of circ-PGAM1 and miR-542-3p on cell biological behaviors including proliferation, migration, invasion, and apoptosis. The interaction between CDC5L and the PEAK1 gene promoter was confirmed using chromatin immunoprecipitation (ChIP). Circ-PGAM1 was upregulated in EOC tissues, whereas linear PGAM1 was not deregulated in EOC tissues. Silencing of circ-PAGM1 inhibited proliferation, migration, and invasion of ovarian cancer cells and promoted cell apoptosis. MiR-542-3p was downregulated in EOC tissues, and miR-542-3p overexpression inhibited malignant progression of ovarian cancer cells. Circ-PGAM1 directly interacted with miR-542-3p, with mutual negative feedback between them. CDC5L was a direct target of miR-542-3p and played an oncogenic role in ovarian cancer cells. Furthermore, the CDC5L protein binds directly to the PEAK1 promoter to promote its transcription. PEAK1 overexpression activated ERK1/2 and JAK2 signaling pathways and promoted malignant biological behaviors of ovarian cancer cells. Circ-PAGM1 silencing combined with miR-542-3p overexpression played the greatest anticancer role in vivo. The circ-PGAM1/miR-542-3p/CDC5L/PEAK1 pathway played an important role in the progression of ovarian cancer and might be a novel therapeutic target for ovarian cancer.

Zhang C ，Li Y ，Zhao W ，Liu G ，Yang Q ... -  《Cancer Medicine》

RNA-binding protein IGF2BP2 enhances circ_0000745 abundancy and promotes aggressiveness and stemness of ovarian cancer cells via the microRNA-3187-3p/ERBB4/PI3K/AKT axis.

Circular RNAs (circRNAs) are increasingly recognized as important regulators in cancer including ovarian cancer (OC). This work focuses on the effects of circ_0000745 on the OC development of and molecules involved. Expression of circ_0000745 in collected OC tissues and the acquired OC cell lines was examined by RT-qPCR. The stability of circ_0000745 in cells was examined by RNase R treatment. The target transcripts interacted with circ_0000745 were predicted using bioinformatic systems. Gain- and loss-of-function studies of circ_0000745, microRNA (miR)-3187-3p and erb-b2 receptor tyrosine kinase 4 (ERBB4) were conducted to determine their functions on proliferation, migration, invasion and stem cell property of OC cells. Circ_0000745 and ERBB4 were abundantly expressed while miR-3187-3p was poorly expressed in OC tissues and cells. Circ_0000745 sequestered miR-3187-3p and blocked its repressive effect on ERBB4. Downregulation of circ_0000745 reduced proliferation, aggressiveness, epithelial-mesenchymal transition, and stemness of SK-OV-3 cells, but this reduction was blocked upon miR-3187-3p inhibition or ERBB4 upregulation. By contrast, artificial induction of circ_0000745 upregulation, miR-3187-3p upregulation and ERBB4 downregulation led to inverse trends in ES-2 cells. ERBB4 promoted the phosphorylation of the PI3K/AKT signaling pathway. An RNA binding protein IGF2BP2 was found to circ_0000745 bind to and promote its expression and stability. This study demonstrated that circ_0000745 upregulated by IGF2BP2 promotes aggressiveness and stemness of OC cells through a miR-3187-3p/ERBB4/PI3K/AKT axis. Circ_0000745 may serve as a promising target for OC treatment.

Wang S ，Li Z ，Zhu G ，Hong L ，Hu C ，Wang K ，Cui K ，Hao C ... -  《Journal of Ovarian Research》

CircCERS6 Suppresses the Development of Epithelial Ovarian Cancer Through Mediating miR-630/RASSF8.

Accumulating evidence have demonstrated that circular RNAs (circRNAs) exert important roles in tumor initiation and progression. Nevertheless, the role and mechanism of circRNA ceramide synthase 6 (circCERS6) in epithelial ovarian cancer (EOC) remain to be clarified. Using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot assay, we measured RNA and protein expression. We analyzed the effects of circCERS6/microRNA-630 (miR-630)/Ras-association domain family member 8 (RASSF8) axis in cell proliferation, migration, and invasion by 5-Ethynyl-2'-deoxyuridine (EdU) assay, colony formation assay, scratch test, and transwell assay. Using RNA-pull down assay and dual-luciferase reporter assay, the interaction between miR-630 and circCERS6 or RASSF8 was verified. The in vivo role of circCERS6 in tumor growth was analyzed using xenograft mice model. CircCERS6 expression was markedly reduced in EOC tissues and cell lines. CircCERS6 overexpression hampered the proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of EOC cells. CircCERS6 directly interacted with miR-630. miR-630 expression was up-regulated in EOC tissues and cell lines. CircCERS6 overexpression-induced anti-tumor effects in EOC were largely reversed by the overexpression of miR-630. RASSF8 was a direct target of miR-630. RASSF8 level was decreased in EOC tissues and cell lines. CircCERS6 up-regulated RASSF8 expression by acting as a molecular sponge for miR-630 in EOC cells. CircCERS6 overexpression-mediated suppressive effects in EOC cells were largely overturned by the silence of RASSF8. CircCERS6 overexpression blocked tumor growth in vivo. CircCERS6 overexpression hampered the proliferation, migration, invasion, and EMT of EOC cells by up-regulating RASSF8 via sponging miR-630.

Li X ，Jiang X ，Lu J ，Lin Y ，Jiang L ，Li Y ，Wan F ，Wang C ... -  《-》

Silencing of hsa_circ_0101145 reverses the epithelial-mesenchymal transition in hepatocellular carcinoma via regulation of the miR-548c-3p/LAMC2 axis.

Jin J ，Liu H ，Jin M ，Li W ，Xu H ，Wei F ... -  《Aging-US》