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 ... -  《-》

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》

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》

miR-744-5p inhibits cellular proliferation and invasion via targeting ARF1 in epithelial ovarian cancer.

miR-744-5p has been demonstrated to play an important role in cancer progression. However, the functions of miR-744-5p in epithelial ovarian cancer (EOC) are not well clarified. In this study, our aim was to investigate the role of miR-744-5p and its underlying molecular mechanism in cell progression of EOC. EOC clinical tissues and matched adjacent ovarian epithelial tissues were collected from 18 patients. Tissues and cell lines were analyzed by qPCR or Western blot to investigate the expression of miR-744-5p and ARF1 in EOC. Cell proliferative capacity was assessed by CCK8 and colony formation assays. Wound healing and transwell assays were performed to evaluate cell migration and invasion. The potential binding relation between miR-744-5p and IRF1 was demonstrated by dual luciferase report assay. The results showed that expression of miR-744-5p was low in EOC clinical tissues and cells. Overexpression of miR-744-5p inhibited proliferation, migration, and invasion of EOC cells. Further mechanistic study identified that ARF1 is a target of miR-744-5p, which is negatively correlated with the expression of miR-744-5p, and overexpression of ARF1 could reverse the inhibition of miR-744-5p on the proliferation, migration, and invasion of EOC cells. Taken together, our results indicated that miR-744-5p attenuated EOC progression via targeting IRF1, providing potential guidance for the clinical treatment of ovarian cancer.

Zhao LG ，Wang J ，Li J ，Li QF ... -  《-》

MicroRNA-145 targets TRIM2 and exerts tumor-suppressing functions in epithelial ovarian cancer.

Epithelial ovarian cancer (EOC) is one of the most common cancers in women worldwide but relatively little is known about its molecular pathogenesis. MicroRNAs, which regulate gene expression post-transcriptionally, have emerged as key players in tumorigenesis. The present study aims to investigate the dysregulation of miR-145 in EOC. miRNA expression was assessed in EOC tissues and cell lines by quantitative reverse transcription (RT)-PCR. Xenograft mouse model was used for evaluation of the effect of miR-145 on tumor growth. Cell proliferation, colony formation assays, invasion assay, flow cytometry, Western blot and gene expression analysis were used for identification of the functional role of miR-145 in EOC cells. Luciferase reporter assay was used to confirm the interaction between miR-145 and its target mRNA 3'-UTR. miR-145 expression was downregulated in EOC tissues and cell lines as compared with normal ovarian tissues. Transfection of miR-145 agomiR significantly inhibited the proliferation, colony forming ability, invasiveness and in vivo tumorigenicity of EOC cells. Transfection of agomiR-145 into EOC cells also markedly induced apoptosis. Furthermore, computational algorithm combined with luciferase reporter assays identified TRIM2 as the direct target of miR-145 in EOC cells. To this end, agomiR-145 downregulated TRIM2 to derepress Bim (a pro-apoptotic Bcl-2 family member degraded by TRIM2). These data confirmed the tumor-suppressing function of miR-145 in EOC and identified TRIM2 as a new miR-145 target. In vivo delivery of agomiR-145 might be a feasible approach for miRNA-directed cancer therapy.

Chen X ，Dong C ，Law PT ，Chan MT ，Su Z ，Wang S ，Wu WK ，Xu H ... -  《-》