Silencing circular RNA hsa_circABCC1 inhibits osteosarcoma progression through down-regulating HDAC4 via sponging miR-591.

BACKGROUND: Circular RNA (circRNA) has been shown to play an important regulatory role in the development of various cancers, including osteosarcoma (OS). However, the role of circRNA ABCC1 (circABCC1) in OS was still poorly understood. The aim of our study was to investigate the role of circABCC1 in OS progression and its potential molecular mechanisms. METHODS: The expression of circABCC1, microRNA-591 (miR-591) and histone deacetylase 4 (HDAC4) in OS tissues or cells was detected by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot (WB) analyses. In vitro experiments, the viability, proliferation, apoptosis, migration, invasion and autophagy of U2OS and HOS cells were assessed in vitro using cell counting kit-8 (CCK-8) assay, 5-ethynyl-29-deoxyuridine (EdU) assay, flow cytometry (FCM) assay, transwell migration and invasion assays (transwell) and WB assay, respectively. Interactions between circABCC1 and miR-591, miR-591 and HDAC4 were confirmed using a dual luciferase reporter gene assay system. The oncogenic role of circABCC1 in OS in vivo was examined by establishing a tumor xenograft model. RESULTS: CircABCC1 was significantly elevated in OS tissues (about 3.1-folds) and cells (U2OS (about 2.1-folds) and HOS (about 2.8-folds)) compared with the control (p < .05). Silencing of circABCC1 significantly reduced the viability and proliferation, promoted apoptosis, impaired migration and invasion, and increased autophagy of U2OS and HOS cells (p < .05). In addition, miR-591 was confirmed to be a target of circABCC1, exerting an opposite effect to circABCC1 (p < .05). MiR-591 attenuation in U2OS and HOS cells was able to reply to the inhibition of cell proliferation, migration and invasion as well as promotion of cell apoptosis and autophagy mediated by silencing circABCC1 (p < .05). HDAC4 was verified to be the target gene of miR-591 in U2OS and HOS cells and was regulated by the circABCC1/miR-591 axis (p < .05), and restoration of HDAC4 levels in U2OS and HOS cells was able to restore the altered cellular function caused by silencing circABCC1 (p < .05). In addition, knockdown of circABCC1 attenuated tumor growth in vivo (p < .05). CONCLUSION: Silencing of circABCC1 inhibits osteosarcoma progression by attenuating HDAC4 expression through sponging miR-591.

CircABCC1 promotes the development of glioma by sponging miR-591 and modulating high-mobility group A2.

CircABCC1 plays an oncogenic role in diverse malignancies. In this study, we investigated its involvement in glioma. The expression of circABCC1 and miR-591 was detected in glioma tissues and cell lines. Gain- and loss-of-function assays were performed to determine the biological effects of circABCC1, miR-591, and high-mobility group A2 (HMGA2) in glioma cells. The circABCC1-mediated competitive endogenous RNA (ceRNA) regulatory mechanism was explored by bioinformatics and the luciferase reporter assay combined with the biotinylated RNA pulldown assay. The effect of circABCC1 on the tumorigenicity of glioma in vivo was detected by constructing xenografts in nude mice. CircABCC1 was highly expressed, and miR-591 was downregulated in glioma tissues and cells. Suppression of circABCC1 repressed the malignant behaviors of glioma cells and tumor growth. Through the ceRNA mechanism, circABCC1 interacts with miR-591 to regulate the expression of HMGA2. CircABCC1 functions as an oncogene to promote the progression of glioma via the regulation of miR-591/HMGA2 signaling. In summary, as revealed by our study, circABCC1 promotes the expression of HMGA2 via sponging of miR-591, thus affecting glioma progression as an important onco-circRNA.

Knockdown of Circ_SLC39A8 protects against the progression of osteoarthritis by regulating miR-591/IRAK3 axis.

BACKGROUND: The dysregulation of circular RNAs (circRNAs) has been identified in various human diseases, including osteoarthritis (OA). The purpose of this study was to identify the role and mechanism of circ_SLC39A8 in regulating the progression of OA. METHODS: The expression levels of circ_SLC39A8, miR-591, and its potential target gene, interleukin-1-receptor-associated kinase 3 (IRAK3), were identified by quantitative real-time polymerase chain reaction (qRT-PCR). Cell viability and apoptosis were determined by Cell Counting Kit-8 (CCK-8) assay and flow cytometry, respectively. The relationship between miR-591 and circ_SLC39A8 or IRAK3 was predicted by bioinformatics tools and verified by dual-luciferase reporter. RESULTS: Circ_SLC39A8 and IRAK3 were upregulated and miR-591 was downregulated in OA cartilage tissues. Knockdown of circ_SLC39A8 inhibited apoptosis and inflammation in OA chondrocytes, while these effects were reversed by downregulating miR-591. Promotion cell viability effects of miR-591 were partially reversed by IRAK3 overexpression. CONCLUSION: Our findings indicated that knockdown of circ_SLC39A8 delayed the progression of OA via modulating the miR-591-IRAK3 axis, providing new insight into the molecular mechanisms of OA pathogenesis.

Hsa_circ_0069094 accelerates cell malignancy and glycolysis through regulating the miR-591/HK2 axis in breast cancer.

Circular RNAs (circRNAs) are implicated in the initiation and advancement of diverse tumors. CircRNA hsa_circ_0069094 (circ_0069094) has been reported to be upregulated in BC, but the biological role of circ_0069094 in BC is indistinct. Hence, we aimed to survey the biological role of circ_0069094 in BC. In the present study, we verified that circ_0069094 was upregulated in BC tissues and cells. BC patients with high circ_0069094 expression had a poor prognosis. Functional analysis revealed that circ_0069094 silencing induced apoptosis, curbed proliferation, and reduced glycolysis in BC cells in vitro, but circ_0069094 overexpression had an opposing influence. Also, circ_0069094 knockdown reduced BC growth in vivo. Mechanically, circ_0069094 was validated as a decoy for miR-591, which targeted HK2. Importantly, circ_0069094 sponged miR-591 to regulate HK2 expression. Both miR-591 silencing and HK2 overexpression counteracted circ_0069094 inhibition-mediated influence on cell proliferation, apoptosis, and glycolysis in BC cells. In conclusion, these results indicated that circ_0069094 facilitated cell malignancy and glycolysis by upregulating HK2 through adsorbing miR-591, suggesting that circ_0069094 might be a prognostic biomarker and therapeutic target for BC.

Circ_0091581 Promotes the Progression of Hepatocellular Carcinoma Through Targeting miR-591/FOSL2 Axis.

BACKGROUND: Circular RNAs (circRNAs) have shown crucial regulatory roles in cancer biology. We aimed to uncover the role and underlying mechanism of circ_0091581 in hepatocellular carcinoma (HCC) progression. METHODS: The abundance of circ_0091581, microRNA-591 (miR-591) and FOS like 2, AP-1 transcription factor subunit (FOSL2) was measured by quantitative real-time polymerase chain reaction. Cell viability, colony formation ability, and invasion ability were assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, colony formation assay, and transwell invasion assay. The migration ability was analyzed by transwell migration assay and wound healing assay. Flow cytometry was used to evaluate the cell cycle and apoptosis of HCC cells. The interaction between miR-591 and circ_0091581 or FOSL2 was predicted by Circular RNA Interactome database or TargetScan database and confirmed by dual-luciferase reporter assay and RNA immune co-precipitation assay. FOSL2 protein expression was measured by Western blot assay. Xenograft tumor assay was conducted to analyze the role of circ_0091581 in HCC tumor growth in vivo. RESULTS: Circ_0091581 was highly expressed in HCC tissue samples and cell lines in contrast to that in adjacent normal tissue samples and THLE-2 cell line. Circ_0091581 accelerated the viability, colony formation, metastasis, and cell cycle, while it impeded the apoptosis of HCC cells. MiR-591 bound to circ_0091581, and circ_0091581 knockdown-mediated effects in HCC cells were largely overturned by miR-591 silencing. FOSL2 was a target of miR-591, and FOSL2 overexpression largely reversed miR-591 accumulation-induced influences in HCC cells. FOSL2 protein expression was down-regulated by circ_0091581 silencing, and the addition of miR-591 inhibitor partly recovered the expression of FOSL2 in HCC cells. Circ_0091581 interference notably suppressed HCC tumor growth in vivo. CONCLUSION: Circ_0091581 acted as an oncogene to enhance the viability, colony formation, metastasis and cell cycle and inhibit the apoptosis of HCC cells through targeting miR-591/FOSL2 axis.

MiR-591 functions as tumor suppressor in breast cancer by targeting TCF4 and inhibits Hippo-YAP/TAZ signaling pathway.

BACKGROUND: MicroRNAs have been involved in regulating crucial biological function in some tumors. However, the clinical role and functional effects of miR-591 in breast cancer remain unknown. METHODS: The expression of miR-591 was detected in breast cancer tissues and their paired normal tissues by qRT-PCR. Functional assays were performed to confirm the effects of miR-591 on the proliferation and invasion of breast cancer. Bioinformatics analysis, luciferase reporter assays, western blot and in vitro assays were used to confirm that TCF4 was a target gene of miR-591. Western blot analysis was carried out to analyze the relationship between miR-591 expression and YAP1 expression in breast cancer. RESULTS: We found that miR-591 expression levels were significantly downregulated in breast cancer tissues compared to adjacent normal tumor tissues. Lower miR-591 expression notably related to lymph node metastasis and advanced TNM stage in patients with breast cancer. In vitro, cell proliferation and invasion were inhibited by transfection of miR-591 mimic in breast cancer cells, but were promoted by transfection of miR-591 inhibitor, compared to the controls. In vivo, we also found that miR-591 mimic significantly inhibited cell proliferation ability. Moreover, we identified that TCF4 was a direct target of miR-591 in breast cancer. TCF4 mediated the inhibiting effects of miR-591 on cell proliferation and invasion in breast cancer cells. In additional, we revealed that miR-591 overexpression significantly inhibited the Hippo-YAP/TAZ signaling pathway in breast cells by downregulated YAP1 expression in breast cells. CONCLUSION: Together, these results indicated that miR-591 is downregulated in breast cancer and could act as a potential target of breast cancer treatment.

Overexpression of micro ribonucleic acid-591 inhibits cell proliferation and invasion of malignant pleural mesothelioma cells.

BACKGROUND: Malignant pleural mesothelioma (MPM) is an aggressive cancer refractory to current therapies. Reduced expression of micro ribonucleic acid (miR)-591 in a range of cancer types has suggested it is a potent tumor suppressor, and overexpression has been shown to inhibit tumor cell growth. The role of miR-591 in MPM is largely unknown. METHODS: miR-591 was over-expressed in vitro using micro RNA mimics in three MPM cell lines (H513, H2052, H2373), and effects on tumor cell growth, proliferation, invasion, and target gene expression were assessed. RESULTS: miR-591 mimic was introduced into MPM cell lines to overexpress this microRNA. The cellular growth, proliferation, and invasive capability was significantly inhibited after overexpression of miR-591. Growth inhibition caused by miR-591 correlated with upregulation of p21 and Bax. Reduced invasive capability correlated with downregulation of matrix metalloproteinase-2 and transforming growth factor-ß1. CONCLUSION: miR-591 is a potent tumor suppressor in MPM. Overexpression of miR-591 may represent a novel therapeutic approach for MPM.