AUF1-induced circular RNA hsa_circ_0010467 promotes platinum resistance of ovarian cancer through miR-637/LIF/STAT3 axis.

BACKGROUND: Increasing evidences has indicated that primary and acquired resistance of ovarian cancer (OC) to platinum is mediated by multiple molecular and cellular factors. Understanding these mechanisms could promote the therapeutic efficiency for patients with OC. METHODS: Here, we screened the expression pattern of circRNAs in samples derived from platinum-resistant and platinum-sensitive OC patients using RNA-sequencing (RNA-seq). The expression of hsa_circ_0010467 was validated by Sanger sequencing, RT-qPCR, and fluorescence in situ hybridization (FISH) assays. Overexpression and knockdown experiments were performed to explore the function of hsa_circ_0010467. The effects of hsa_circ_0010467 on enhancing platinum treatment were validated in OC cells, mouse model and patient-derived organoid (PDO). RNA pull-down, RNA immunoprecipitation (RIP), and dual-luciferase reporter assays were performed to investigate the interaction between hsa_circ_0010467 and proteins. RESULTS: Increased expression of hsa_circ_0010467 is observed in platinum-resistant OC cells, tissues and serum exosomes, which is positively correlated with advanced tumor stage and poor prognosis of OC patients. Hsa_circ_0010467 is found to maintain the platinum resistance via inducing tumor cell stemness, and silencing hsa_circ_0010467 substantially increases the efficacy of platinum treatment on inhibiting OC cell proliferation. Further investigation reveals that hsa_circ_0010467 acts as a miR-637 sponge to mediate the repressive effect of miR-637 on leukemia inhibitory factor (LIF) and activates the LIF/STAT3 signaling pathway. We further discover that AUF1 could promote the biogenesis of hsa_circ_0010467 in OC. CONCLUSION: Our study uncovers the mechanism that hsa_circ_0010467 mediates the platinum resistance of OC through AUF1/hsa_circ_0010467/miR-637/LIF/STAT3 axis, and provides potential targets for the treatment of platinum-resistant OC patients.

Circ_0000877 accelerates proliferation and immune escape of non-small cell lung cancer cells by regulating microRNA-637/E2F2 axis.

BACKGROUND: Recently, circular RNA (circRNA) has become a vital targeted therapy gene for non-small-cell lung cancer (NSCLC) cells. CircRNA_0000877 (Circ_0000877) has been researched in diffuse large B-cell lymphoma (DLBCL). However, whether circ_0000877 regulated NSCLC cell progression is still poorly investigated. The research attempted to investigate the influence of circ_0000877 in NSCLC. METHODS: Circ_0000877 levels in NSCLC tissues and cell lines were determined applying RT-qPCR. Cell functions were evaluated by CCK-8, EdU, flow cytometry, ELISA, and western blot. Gene interactions were predicted by Cirular RNA interactome database and Target Scan website and certified by dual-luciferase reporter, RIP, and RNA pull-down assays. Finally, mice experimental model was established to explore the effects of circ_0000877 on tumor growth in vivo. RESULTS: The elevated trend of circ_0000877 expression was discovered in NSCLC tissues compared to para-carcinoma tissues. The clinicopathological data uncovered that up-regulated circ_0000877 was linked to tumor size, differentiation, and TNM stages of NSCLC patients. Knockdown of circ_0000877 inhibited the proliferation, triggered apoptosis, and prohibited immune escape in NSCLC cells. It was certified that miR-637 was directly interacted with circ_0000877 and targeted by E2F2. Overexpressed E2F2 strongly overturned the functions of circ_0000877 knockdown in NSCLC cells. Mice experimental data demonstrated that circ_0000877 knockdown suppressed tumor growth in vivo. CONCLUSION: The research demonstrated that circ_0000877 exhibited the promotive effect on NSCLC cells proliferation and immune escape by regulating miR-637/E2F2 axis.

Circ_0007429/miR-637/TRIM71/Ago2 axis participates in the regulation of proliferation, migration, invasion, apoptosis, and aerobic glycolysis of HCC.

CircRNAs play an important role in the progression of hepatocellular carcinoma (HCC), however, the role of circ_0007429 in HCC remains unknown. Using bioinformatics tools, we selected circ_0007429 that was most highly expressed in HCC tissues and investigated its role in HCC progression. Immunohistochemistry, plasmid transfection, real-time quantitative PCR, and western blot analysis were used to identify the relationship between circ_0007429 and its potential target, miR-637, and TRIM71. The regulatory effect of circ_0007429 on miR-637/TRIM71/Ago2 signaling and its key role in HCC progression were studied in vitro. A nude mouse xenograft model was used to examine tumor growth in vivo. Circ_0007429 and TRIM71 expression were upregulated, while miR-637 expression was downregulated in HCC tissues and cells compared with their expression in control groups. Knockdown of circ_0007429 enhanced apoptosis in HCC cells, while impeded proliferation, migration, invasion, and aerobic glycolysis, which were reversed by miR-637 inhibitor. High levels of circ_0007429 correlated with a poor survival rate of HCC patients. Additionally, circ_0007429 interfering inhibited tumor growth in vivo. TRIM71 directly bound to miR-637 and inhibited Ago2 expression. Moreover, circ_0007429 promotes aerobic glycolysis in HCC cells through the miR/TRIM71/Ago2 axis. Circ_0007429 promotes HCC progression by promoting cell proliferation, migration, invasion, and aerobic glycolysis and by inhibiting cell apoptosis through the miR/TRIM71/Ago2 axis. These results provide molecular insights into the mechanism of HCC and suggest that circ_0007429 could be a therapeutic target for HCC.

Circ_0081054 facilitates melanoma development via sponging miR-637 and regulating RAB9A.

BACKGROUND: Accumulating evidence announces that aberrantly expressed circRNAs were closely related to the development of human cancers. However, the role and mechanism of multiple circRNAs remain unclear. Our work aimed to disclose the functional role and mechanism of circ_0081054 in melanoma. METHODS: Quantitative real-time polymerase chain reaction assay was utilized to detect circ_0081054, microRNA-637 (miR-637) and RAB9A (member RAS oncogene family) mRNA expression. Cell proliferative ability was evaluated via Cell Counting Kit-8 and colony formation assay. Cell invasion was assessed by using wound healing assay. RESULTS: The significant upregulation of circ_0081054 was detected in melanoma tissues and cells. The proliferation, migration, glycolytic metabolism, and angiogenesis in melanoma cells were suppressed, while apoptosis was promoted following the silence of circ_0081054. In addition, circ_0081054 could target miR-637, and miR-637 inhibitor could reverse the effects of circ_0081054 deficiency. Furthermore, RAB9A was a target gene for miR-637 and RAB9A overexpression could reverse the effects of miR-637 overexpression. In addition, the deficiency of circ_0081054 hampered tumor growth in vivo. Moreover, circ_0081054 could regulate RAB9A expression by sponging miR-637. CONCLUSION: All results indicated that circ_0081054 promoted the malignant behaviors of melanoma cells partly by regulating the miR-637/RAB9A molecular axis.

miR-637 Prevents Glioblastoma Progression by Interrupting ZEB2/WNT/ß-catenin Cascades.

Glioblastomas (GBMs) are the most frequent primary malignancies in the central nervous system. Aberrant activation of WNT/ß-catenin signaling pathways is critical for GBM malignancy. However, the regulation of WNT/ß-catenin signaling cascades remains unclear. Presently, we observed the increased expression of ZEB2 and the decreased expression of miR-637 in GBM. The expression of miR-637 was negatively correlated with ZEB2 expression. miR-637 overexpression overcame the ZEB2-enhanced cell proliferation and G1/S phase transition. Besides, miR-637 suppressed the canonical WNT/ß-catenin pathways by targeting WNT7A directly. Gain- and loss-of-function experiments with U251 mice demonstrated that miR-637 inhibited cell proliferation and arrested the G1/S phase transition, leading to tumor growth suppression. The collective findings suggest that ZEB2 and WNT/ß-catenin cascades merge at miR-637, and the ectopic expression of miR-637 disturbs ZEB2/WNT/ß-catenin-mediated GBM growth. The findings provide new clues for improving ß-catenin-targeted therapy against GBM.

Circ_0017274 acts on miR-637/CDX2 axis to facilitate cisplatin resistance in gastric cancer.

Currently, a substantial amount of circular RNAs (circRNAs) are closely associated with cancer development and the occurrence of drug resistance, however, circ_0017274 in cisplatin (CDDP) resistance in gastric cancer (GC) has not been addressed. Real-time quantitative polymerase chain reaction (RT-qPCR) and western blot were utilized for circ_0017274, microRNA-637 (miR-637) and caudal-related homeobox transcription factor 2 (CDX2) contents analysis. Analysis of IC50, proliferation, cell cycle, apoptosis, migration and invasion of GC cells using Cell Counting Kit-8 (CCK8), 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry or transwell assays. Interaction between miR-637 and circ_0017274 or CDX2 was validated under the application of luciferase reporter system, RNA immunoprecipitation (RIP) analysis, and pull-down assay. The effect of circ_0017274 on CDDP sensitivity in vivo was tapped by xenograft models. Circ_0017274 and CDX2 had higher content in CDDP-resistant GC tissues and cells, while miR-637 had lower content. CDDP resistance and development of GC cells were arrested when circ_0017274 level was reduced in vitro. MiR-637 acted as a target of circ_0017274, and miR-637 downregulation abated the phenomenon of elevated sensitivity of sh-circ_0017274 to CDDP. MiR-637 was also demonstrated to interact with CDX2 and to co-regulate CDDP sensitivity in GC cells. The xenograft models also established that circ_0017274 downregulation strengthened CDDP sensitivity and thus curtailed tumour growth in vivo. Circ_0017274 downregulation boosted CDDP sensitivity by acting on miR-637/CDX2 in CDDP-resistant GC cells.

Circ_SNX27 regulates hepatocellular carcinoma development via miR-637/FGFR1 axis.

BACKGROUND: Circular RNAs (circRNAs) serve as critical regulatory factors in cancer development. Nonetheless, the potential regulatory mechanism of circRNA sorting nexin 27 (circ_SNX27) in hepatocellular carcinoma (HCC) is still unknown. METHODS: The circ_SNX27, microRNA-637 (miR-637), and fibroblast growth factor receptor 1 (FGFR1) levels were quantified by quantitative real-time polymerase chain reaction and western blot analysis. Next, function experiments were conducted using in vitro assays and in vivo senograft study. The relationship between miR-637 with circ_SNX27 or FGFR1 was uncovered by dual-luciferase reporter and RNA pull-down assays. RESULTS: The circ_SNX27 and FGFR1 levels were up-regulated, but miR-637 content was reduced in HCC. Circ_SNX27 down-regulation inhibited HCC cell proliferation, motility, and invasion and promoted apoptosis in vitro, as well as weakened tumor growth in vivo. Circ_SNX27 served as a sponge of miR-637 to promote FGFR1 expression. MiR-637 reduction abolished the restrained effect of circ_SNX27 absence on HCC cell development. Moreover, miR-637 curbed HCC cell malignant phenotype by regulating FGFR1. CONCLUSION: Circ_SNX27 contributed to HCC development via miR-637/FGFR1 axis, offering a new idea for the treatment of HCC.

Diagnostic value of miR-637 in patients with atherosclerosis and its predictive significance for the future cardiovascular events.

OBJECTIVES: Atherosclerosis is a common vascular disease. MiR-637 has been demonstrated to be low-expressed in hypertensive patients, and atherosclerosis is closely related to hypertension. Therefore, this study speculated that miR-637 may play an important role in the development of atherosclerosis. In brief, this study examined the expression level of miR-637 in patients with atherosclerosis and further analyzed its clinical value in patients with atherosclerosis. METHODS: The expression level of miR-637 was detected in serum from 86 patients with atherosclerosis and 75 healthy controls by using quantitative reverse transcription-polymerase chain reaction. The receiver operating characteristic curve was used to assess the diagnostic value of miR-637 in atherosclerosis. Pearson's correlation analysis was performed to evaluate the relationship between serum miR-637 and different clinical parameters. The prognostic value of miR-637 in atherosclerosis was analyzed by the Kaplan-Meier survival curve and multivariate cox regression analysis. RESULTS: Compared with healthy individuals, miR-637 was downregulated in the serum of atherosclerosis patients. The receiver operating characteristic curve suggested the high diagnostic value of miR-637 for atherosclerosis, with the AUC of 0.853, specificity of 77.9%, and sensitivity of 80.0%. The expression level of miR-637 was negatively correlated with CIMT (r = -0.8101, P < 0.0001) and CRP (r = -0.6154, P < 0.0001), respectively. Survival analysis indicated that miR-637 was also found to be an independent prognostic factor for atherosclerosis. CONCLUSIONS: MiR-637 is a potential noninvasive diagnostic marker of atherosclerosis and has important predictive value for the occurrence of future cardiovascular events.

The circRNA circSEPT9 mediated by E2F1 and EIF4A3 facilitates the carcinogenesis and development of triple-negative breast cancer.

BACKGROUND: Increasing studies have shown that circRNA is closely related to the carcinogenesis and development of many cancers. However, biological functions and the underlying molecular mechanism of circRNAs in triple-negative breast cancer (TNBC) remain largely unclear so far. METHODS: Here, we investigated the expression pattern of circRNAs in four pairs of TNBC tissues and paracancerous normal tissues using RNA-sequencing. The expression and prognostic significance of circSEPT9 were evaluated with qRT-PCR and in situ hybridization in two TNBC cohorts. The survival curves were drawn by the Kaplan-Meier method, and statistical significance was estimated with the log-rank test. A series of in vitro and in vivo functional experiments were executed to investigate the role of circSEPT9 in the carcinogenesis and development of TNBC. Mechanistically, we explored the potential regulatory effects of E2F1 and EIF4A3 on biogenesis of circSEPT9 with chromatin immunoprecipitation (ChIP), luciferase reporter and RNA immunoprecipitation (RIP) assays. Furthermore, fluorescent in situ hybridization (FISH), luciferase reporter and biotin-coupled RNA pull-down assays were implemented to verify the relationship between the circSEPT9 and miR-637 in TNBC. RESULTS: Increased expression of circSEPT9 was found in TNBC tissues, which was positively correlated with advanced clinical stage and poor prognosis. Knockdown of circSEPT9 significantly suppressed the proliferation, migration and invasion of TNBC cells, induced apoptosis and autophagy in TNBC cells as well as inhibited tumor growth and metastasis in vivo. Whereas up-regulation of circSEPT9 exerted opposite effects. Further mechanism research demonstrated that circSEPT9 could regulate the expression of Leukemia Inhibitory Factor (LIF) via sponging miR-637 and activate LIF/Stat3 signaling pathway involved in progression of TNBC. More importantly, we discovered that E2F1 and EIF4A3 might promote the biogenesis of circSEPT9. CONCLUSIONS: Our data reveal that the circSEPT9 mediated by E2F1 and EIF4A3 facilitates the carcinogenesis and development of triple-negative breast cancer through circSEPT9/miR-637/LIF axis. Therefore, circSEPT9 could be used as a potential prognostic marker and therapeutical target for TNBC.

circ-NOTCH1 acts as a sponge of miR-637 and affects the expression of its target gene Apelin to regulate gastric cancer cell growth.

Gastric cancer (GC) is a major cause of cancer-related deaths worldwide, and has a low survival rate, low cure rate, high recurrence rate, and poor prognosis. Recent studies have indicated that circular RNAs (circRNAs) have important functions in the occurrence and progression of GC. Studies on circ-NOTCH1, which was shown to be highly expressed in GC, have indicated that miR-637 binds to circ-NOTCH1 at multiple sites, and a dual-luciferase reporter gene assay further confirmed that miR-637 indeed targeted circ-NOTCH1 and Apelin. Circ-NOTCH1 and Apelin are highly expressed in GC cells and tissues, whereas the expression of miR-637 is reduced. Circ-NOTCH1 and miR-637 do not regulate each other's expression levels, but circ-NOTCH1significantly upregulates the expression of the miR-637 target gene Apelin, whereas miR-637 inhibites the expression of Apelin. Examination of GC cells showed that circ-NOTCH1 enhances cell proliferation and invasiveness, and reduces cell apoptosis; these effects were reversed by miR-637, which could terminate the above effects of circ-NOTCH1. When co-transfected with the circ-NOTCH1 overexpression plasmid and Apelin siRNAs, there were no obvious changes to the levels of cell proliferation, apoptosis, or invasiveness. Therefore, in GC cells, circ-NOTCH1 inhibits the transcriptional activity of miR-637, thereby upregulating the expression of its target gene Apelin and regulating cell proliferation, apoptosis, and invasiveness. This finding provides more experimental evidence for the function of circRNA in GC.

Downregulation of miR-637 promotes vascular smooth muscle cell proliferation and migration via regulation of insulin-like growth factor-2.

BACKGROUND: Dysregulation of the proliferation and migration of vascular smooth muscle cells (VSMCs) is a crucial cause of atherosclerosis. MiR-637 exerts an antiproliferative effect on multiple human cells. Its impact on atherosclerosis remains largely unexplored. METHODS: Real-time PCR was used to determine miR-637 expression in samples from atherosclerosis patients and animal models. Its expression in VSMC dysfunction models (induced by ox-LDL) was also measured. The proliferation and migration of VSMCs were respectively tested using CCK-8 and Transwell assays, and apoptosis was measured using flow cytometry. The Targetscan database was used to predict the target genes of miR-637. Interaction between miR-637 and the potential target gene was validated via real-time PCR, western blotting and a luciferase reporter assay. RESULTS: MiR-637 expression was significantly lower in atherosclerosis patient and animal model samples. It also decreased in a dose- and time-dependent manner in animal models with ox-LDL-induced atherosclerosis. Transfection with miR-637 mimics suppressed the proliferation and migration of VSMCs while promoting apoptosis, while transfection with miR-637 inhibitors had the opposite effects. We also validated that insulin-like growth factor-2 (IGF-2), a crucial factor in the pathogenesis of atherosclerosis, serves as a target gene for miR-637. CONCLUSION: MiR-637 targeting IGF-2 contributes to atherosclerosis inhibition and could be a potential target for this disease.

Upregulation of circular RNA circ-ERBB2 predicts unfavorable prognosis and facilitates the progression of gastric cancer via miR-503/CACUL1 and miR-637/MMP-19 signaling.

Gastric cancer (GC) is one of the most common malignancies of digestive system with aggressive phenotypes. Circular RNAs (circRNAs) play a pivotal function in cancer initiation and development. Nevertheless, the function and mechanism of circRNAs in gastric cancer (GC) is not fully understood. We found circ-ERBB2 was strikingly increased in GC tissues and cells. Noticeably, circ-ERBB2 upregulation in tumorous tissues was linked to patients' tumor size, depth of invasion, and overall survival. A series of gain and loss-of-function assays indicated its oncogenic role in GC cells, including cell proliferation, apoptosis, migration and invasion. We further predicted and identified circ-ERBB2 sponged miR-503 and miR-637 by bioinformatics analysis and luciferase reporter system. CACUL1 and MMP-19 were then predicted and confirmed as the target of miR-503 and miR-637, respectively. Furthermore, rescue assays indicated that circ-ERBB2 promoted tumor growth and invasion via miR-503/CACUL1 and miR-637/MMP-19 pathways, respectively. In summary, these findings demonstrated that circ-ERBB2 functions as an oncogene in GC and might be useful in developing promising therapies for this fatal malignancy.

Primate-specific miRNA-637 inhibited tumorigenesis in human pancreatic ductal adenocarcinoma cells by suppressing Akt1 expression.

As a primate-specific microRNA, miR-637 has been discovered for nearly 10 years. Our previous study demonstrated that miR-637 acted as a suppressor in hepatocellular carcinoma. However, its biomedical significance in pancreatic cancer remains obscure. In the present study, miR-637 was found to be significantly downregulated in pancreatic ductal adenocarcinoma (PDAC) cell lines and most of the PDAC specimens. Furthermore, the enforced overexpression of miR-637 dramatically inhibited cell proliferation and induced apoptosis of PDAC cells. Akt1, as a serine/threonine-protein kinase, has been identified as an oncogene in multiple cancers including pancreatic cancer. Our data confirmed that Akt1 was a novel target for miR-637, and its knockdown also induced cell growth inhibition and apoptosis in PDAC cells. In conclusion, our data indicated that miR-637 acted as a tumor-suppressor in PDAC, and the suppressive effect was mediated, at least partially, by suppressing Akt1 expression.

Up-regulation of circular RNA hsa_circ_0037909 promotes essential hypertension.

AIMS: Essential hypertension (EH) is a high prevalence disease facing a public health challenge. People were little known about the genetics of diagnosing the cause of EH. Circular RNAs that have a continuous cycle of covalent closure, without affected by RNA exonuclease, and are more stable and hard to degrade may involve into the molecule regulation mechanism of EH as an important biomedical. METHODS: qRT-PCR was used to analyze circRNAs in total volume of human blood and the induced human aortic endothelial cells (HAECs) and human umbilical vein endothelial cells (HUVECs). Our case-control study was involved with 48 pairs of case controls with sex and age (±3 years) match. We conducted t test, Pearson's χ2 test, and receiver operating characteristics (ROC) curve analysis for the corresponding analysis. RESULTS: The expression level of hsa_circ_0037909 in EH patients was significantly higher than that in the healthy controls (P = 0.007), and the expression level of hsa-miR-637 in EH patients was significantly lower in than that in the healthy controls (P = 0.039); the same result appears in the HAECs and HUVECs. Hsa-miR-637 (adjusted P = 0.018), hsa_circ_0037909 (adjusted P = 0.005), HDL (adjusted P = 0.024), and serum creatinine (adjusted P = 0.014) were brought into the model which performed logistic regression analysis. The combination of two RNAs was excellent (P < 0.001) through ROC curve analysis. Hsa_circ_0037909 was significantly positively correlated with serum creatinine (P < 0.001) and low-density lipoprotein (LDL) (P = 0.017). CONCLUSIONS: Our findings suggested that the combination of hsa_circ_0037911 and hsa-miR-637 may be a significant important biomarker for early diagnosis of EH. Hsa_circ_0037909 may affect serum creatinine or LDL leading to the formation of EH.

MiR-637 suppresses melanoma progression through directly targeting P-REX2a and inhibiting PTEN/AKT signaling pathway.

MicroRNAs (miRNAs) play important roles in melanoma. Although miR-637 has been suggested to be a tumor suppressor in several cancers, its function in melanoma and the molecular mechanism behind that function remain unclear. In this study, we investigated the role of miR-637 in human melanoma and explored its relevant mechanisms. We found that the expression of miR-637 is significantly downregulated in melanoma tissues and cell lines. While overexpression of miR-637 inhibited melanoma cell proliferation and cell cycle G1-S transition, and induced apoptosis. Inhibition of miR-637 promoted cell proliferation and G1-S transition, and suppressed apoptosis. Subsequent investigation revealed that miR-637 expression was inversely correlated with P-REX2a expression in melanoma tissues. P-REX2a was determined to be a direct target of miR-637 by using a luciferase reporter assay. Overexpression of miR-637 decreased P-REX2a expression at both the mRNA and protein levels, and suppression of miR-637 increased P-REX2a expression. Importantly, silencing P-REX2a recapitulated the cellular and molecular effects seen upon miR-637 overexpression, whereas, overexpression of P-REX2a eliminated the effects of miR-637 overexpression on melanoma cells. Furthermore, both enforced expression of miR-637 or silencing of P-REX2a resulted in activation of PTEN, leading to a decline in AKT phosphorylation. Taken together, our study demonstrates that miR-637 inhibites melanoma cell proliferation by activation of AKT signaling pathway and induces apoptosis through regulation of Bcl-2/Bax expression via targeting P-REX2a. These findings suggest that miR-637 plays a crucial role in melanoma progression, and may serve as a potential novel target for melanoma therapy.

Circ_0003575 knockdown alleviates ox-LDL-induced human aortic endothelial cell dysfunction in atherosclerosis by miR-637/TRAF6 axis.

BACKGROUND: Circular RNAs (circRNAs) are involved in the progression of atherosclerosis (AS). The present study aimed to determine the functions and mechanism of circ_0003575 in AS. METHODS: Oxidized low-density lipoprotein (ox-LDL) was used to induce human aortic endothelial cells (HAECs) to establish an AS cell model. Cell Counting Kit-8 (CCK-8) assay and 5'-ethynyl-2'-deoxyuridine (EdU) assay were conducted to assess cell proliferation. Flow cytometry analysis was utilized to quantify cell apoptosis. Tube formation assay was performed to analyze angiogenesis ability. Enzyme linked immunosorbent assay (ELISA) was used to examine the concentrations of inflammatory factors. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blot were manipulated for the expression of circ_0003575, microRNA-637 (miR-637) and TNF receptor associated factor 6 (TRAF6). Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were adopted to estimate the downstream targets of circ_0003575. RESULTS: Ox-LDL treatment repressed the proliferation and angiogenesis and promoted the apoptosis and inflammation in HAECs. Circ_0003575 knockdown ameliorated ox-LDL-induced injury of HAECs. Circ_0003575 interacted with mi-R-637, which directly targeted TRAF6. Inhibition of miR-637 reversed the impacts of circ_0003575 knockdown on HAEC injury. Moreover, miR-637 overexpression promoted cell proliferation and angiogenesis and inhibited cell apoptosis and inflammation by targeting TRAF6 in ox-LDL-treated HAECs. Further, circ_0003575 silencing inhibited the activation of NF-κB pathway. CONCLUSION: Circ_0003575 knockdown alleviated ox-LDL-induced HAEC damage by regulating miR-637/TRAF6 and NF-κB pathways.

The function of miR-637 in non-small cell lung cancer progression and prognosis.

BACKGROUND: Non-small cell lung cancer (NSCLC) is the most common type of lung cancer with a high mortality rate and poor prognosis. miR-637 has been reported to regulate tumor progression and act as a prognosis biomarker of various cancers. Its functional role in NSCLC was investigated in this study. METHODS: The expression level of miR-637 in NSCLC tissues and adjacent normal tissues of 123 NSCLC patients was analyzed by qRT-PCR. The association between miR-637 and clinical pathological features in the prognosis of patients was analyzed. Cell transfection was performed to overexpress or knockdown miR-637 in H1299 and HCC827. The proliferation, migration, and invasion of H1299 and HCC827 were evaluated by CCK8 and Transwell assay. RESULTS: miR-637 expression was significantly decreased in NSCLC tissues and cell lines relative to normal tissues and cells. The survival rate of NSCLC patients with low miR-637 expression was lower than that of patients with high miR-637 expression. Additionally, miR-637 served as a tumor suppressor that inhibited cell proliferation, migration, and invasion of NSCLC. CONCLUSION: Downregulation of miR-637 in NSCLC was associated with TNM stage and poor prognosis of patients and served as a tumor suppressor in NSCLC. These results provide a potential strategy to control NSCLC.

Circ_0033596 depletion ameliorates oxidized low-density lipoprotein-induced human umbilical vein endothelial cell damage.

BACKGROUND: Previous data have shown that circ_0033596 is involved in the pathogenesis of atherosclerosis (AS). The study aims to reveal the detailed mechanism of circ_0033596 in AS. METHODS: Human umbilical vein endothelial cells (HUVECs) were treated with oxidized low-density lipoprotein (ox-LDL) to establish an AS cell model. Quantitative real-time polymerase chain reaction and western blot were implemented to detect the expression of circ_0033596, miR-637, growth factor receptor bound protein2 (GRB2), BCL2-associated x protein (Bax) and B-cell lymphoma-2 (Bcl-2). Cell viability, proliferation, apoptosis and tube formation were investigated by cell counting kit-8, EdU assay, flow cytometry and tube formation assay, respectively. The production of interleukin (IL-6) and tumor necrosis factor-α (TNF-α) was evaluated by enzyme-linked immunosorbent assay. Oxidative stress was evaluated by lipid peroxidation malondialdehyde assay kit and superoxide dismutase activity assay kit. Dual-luciferase reporter assay, RNA pull-down assay and RIP assay were performed to identify the associations among circ_0033596, miR-637 and GRB2. RESULTS: The expression of circ_0033596 and GRB2 was significantly increased, while miR-637 was decreased in the blood of AS patients and ox-LDL-induced HUVECs compared with controls. Ox-LDL treatment inhibited HUVEC viability, proliferation and angiogenic ability and induced cell apoptosis, inflammation and oxidative stress, while these effects were attenuated after circ_0033596 knockdown. Circ_0033596 interacted with miR-637 and regulated ox-LDL-induced HUVEC damage by targeting miR-637. In addition, GRB2, a target gene of miR-637, participated in ox-LDL-induced HUVEC injury by combining with miR-637. Importantly, circ_0033596 activated GRB2 by interacting with miR-637. CONCLUSION: Circ_0033596 depletion protected against ox-LDL-induced HUVEC injury by miR-637/GRB2 pathway, providing a therapeutic target for AS.

Extracellular vesicle-derived circHIPK3: Novel diagnostic biomarker for lung cancer.

PURPOSE: Lung cancer (LC) is a common malignancy worldwide. A great number of circular RNAs (circRNAs) have been identified that serve crucial roles in cancer development. Extracellular vesicles (EVs) and their contents have been shown to be biomarkers for the diagnosis and prognosis of LC. Thus, we intended to clarify the functional role of EVs-derived circRNA homology domain interacting protein kinase 3 (EVs-circHIPK3) and its underlying mechanism of action. MATERIAL AND METHODS: Bioinformatics analysis was performed to validate the potential of partially circulating HIPK3 in LC diagnosis. EVs were isolated by polyethylene glycol (PEG) precipitation from plasma of 52 LC patients and 30 healthy controls. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was employed to evaluate the expressions of candidate circRNAs (circHIPK3) and microRNA-637 (miR-637, a target of circHIPK3). RESULTS: CircHIPK3 is significantly up-regulated in LC, while miR-637 expression is significantly reduced (p â€‹< â€‹0.05). Receiver operating characteristic (ROC) curve analysis, based on the expression of EVs-circHIPK3, allowed us to distinguish LC from healthy controls (area under the curve, AUC 0.897). CONCLUSIONS: Taken together, our study shows that EV-derived circHIPK3 can serve as a promising biomarker for LC patient diagnosis. However, the downstream mRNA of the circHIPK3/miR-637 axis requires further exploration to enrich our understanding of circHIPK3's mechanism in LC.

Investigation of miR-133a, miR-637 and miR-944 genes expression and their relationship with PI3K/AKT signaling in women with breast cancer.

PURPOSE: MicroRNAs (miRNAs) are regulatory molecules capable of positively or negatively regulating signaling pathways, and are involved in tumorigenesis as well as various aspects of cancer. The purpose of this study was to investigate the expression levels of miR-133a, miR-637, and miR-944 in serum and tumor tissues as well as their relationship with the expression level of phosphatidylinositol-3-kinase (PI3K) and protein kinase-B (AKT) genes and proteins along with their clinical significance in breast cancer. METHODS: The expressions of miR-133a, miR-637, miR-944, PI3K, and AKT genes were examined in the tumor and tumor margin tissues of 40 patients with breast cancer, as well as the serum levels of miR-133a, miR-637, and miR-944 in these patients and 40 healthy groups by quantitative real-time PCR (qRT-PCR). PI3K and AKT proteins expression in tumor and tumor margin tissues were detected using immunohistochemistry (IHC). RESULTS: The expression levels of miR-133a and miR-637 in the tumor tissue and serum of patients were lower than those in the tumor margin tissue and serum of the healthy group, respectively. In addition, the expression level of miR-944 in the tumor tissue was lower than that in the tumor margin tissue, but its expression increased in the serum of cancer patients compared to that in the healthy group. The expression of miR-637 was correlated with tumor location and Her2 receptors, and the expression of miR-944 was correlated with tumor location and family history. PI3K and AKT mRNA and protein levels were higher in the tumor tissues than in the tumor margin tissues (p < 0.05). CONCLUSION: The results of our study revealed that miR-637 has a better diagnostic value in breast cancer than miR-133a and miR-944.