FOXCUT regulates the malignant phenotype of triple-negative breast Cancer via the miR-337-3p/ANP32E Axis.

BACKGROUND: The lack of specific molecular targets and the rapid spread lead to a worse prognosis of triple-negative breast cancer (TNBC). Therefore, identifying new therapeutic and prognostic biomarkers helps to develop effective treatment strategies for TNBC. METHODS: Through preliminary bioinformatics analysis, FOXCUT was found to be significantly overexpressed in breast cancer, especially in TNBC. Tissue samples were collected from 15 TNBC patients, and qRT-PCR was employed to validate the expression of FOXCUT in both TNBC patient tissues and TNBC cell lines. We also carried out the GSEA analysis and KEGG enrichment analysis of FOXCUT. Additionally, the effects of FOXCUT knockdown on TNBC cell malignant behaviors, and aerobic glycolysis were assessed by methods including CCK-8, Transwell, western blot, and Seahorse XF 96 analyses. Moreover, utilizing databases predicting interactions between ceRNAs, corresponding lncRNA-miRNA binding relationships, and miRNA-mRNA interactions were predicted. These predictions were subsequently validated through RNA immunoprecipitation and dual-luciferase reporter assays. RESULTS: FOXCUT exhibited high expression in both TNBC tissues and cell lines, fostering cell malignant behaviors and glycolysis. FOXCUT was found to sponge miR-337-3p, while miR-337-3p negatively regulated the expression of ANP32E. Consequently, FOXCUT ultimately facilitated the malignant phenotype of TNBC by upregulating ANP32E expression. CONCLUSION: This study elucidated the role of FOXCUT in elevating aerobic glycolysis levels in TNBC and driving malignant cancer cell development via the miR-337-3p/ANP32E regulatory axis.

Downregulation of miR-337-3p in hypoxia/reoxygenation neuroblastoma cells increases KCTD11 expression.

Neurodegeneration is linked to the progressive loss of neural function and is associated with several diseases. Hypoxia is a hallmark in many of these diseases, and several therapies have been developed to treat this disease, including gene expression therapies that should be tightly controlled to avoid side effects. Cells experiencing hypoxia undergo a series of physiological responses that are induced by the activation of various transcription factors. Modulation of microRNA (miRNA) expression to alter transcriptional regulation has been demonstrated to be beneficial in treating multiple diseases, and in this study, we therefore explored potential miRNA candidates that could influence hypoxia-induced nerve cell death. Our data suggest that in mouse neuroblasts Neuro-2a cells with hypoxia/reoxygenation (H/R), miR-337-3p is downregulated to increase the expression of Potassium channel tetramerization domain containing 11 (KCTD11) and subsequently promote apoptosis. Here, we demonstrate for the first time that KCTD11 plays a role in the cellular response to hypoxia, and we also provide a possible regulatory mechanism by identifying the axis of miR-337-3p/KCTD11 as a promising candidate modulator of nerve cell survival after H/R exposure.

Exosomes derived from mir-337-3p over-expressing tendon stem cells protect against apoptosis of tenocytes via targeting caspase3.

BACKGROUND: Tendons are important dense fibrous structures connecting muscle to bone, and tendon stem cells (TDSCs) affect their repair and regeneration. The role of TDSC-derived exosomes (TDSC-Exos) is still being unexplored; therefore, this study aimed to investigate the protective effect of TDSC-Exos on tenocytes. METHODS: The TDSCs and tenocytes were all derived from Sprague Dawley (SD) rats. The expression of positive and negative markers of TDSCs were detected by flow cytometry, and the multi-differentiation ability was also detected to identify TDSCs. Exos were derived from TDSCs using ultracentrifugation; furthermore, Exos enriched with microRNA(miR)-377-3p were generated from TDSCs stably overexpressing miR-377-3p after transfection, identified with transmission electron microscopy (TEM), western blot and PKH26 staining assay. Moreover, the cell functions of tenocytes were evaluated by MTT, EdU, transwell, and flow cytometry. Dual luciferase reporter and RNA pull-down assays were used to verify the binding sites of miR-337-3p and caspase3 (CASP3) predicted by Targetscan. RESULTS: Exos (miR-337-3p) were taken up by tenocytes, and promoted the proliferation, migration, and invasion and suppressed the apoptosis of tenocytes in a dose-dependent manner. Bioinformatics analysis showed that CASP3 was a target of miR-377-3p, which was further verified by luciferase and RNA pull-down assays. Moreover, over-expressed CASP3 reversed the effects of Exos (miR-337-3p) on cell functions of tenocytes. CONCLUSIONS: Our findings suggest that Exos derived from miR-337-3p over-expressing TDSCs could potentially protect against tenocyte apoptosis by regulating CASP3. This novel therapeutic approach holds promise for the treatment of tendon injury, offering a glimmer of hope for improved patient outcomes.

MiR-337-3p confers protective effect on facet joint osteoarthritis by targeting SKP2 to inhibit DUSP1 ubiquitination and inactivate MAPK pathway.

OBJECTIVE: To probe the performance of miR-337-3p on the facet joint osteoarthritis (FJOA) and its underlying mechanism. METHODS: qRT-PCR and Western blot were utilized to analyze the levels of miR-337-3p and DUSP1 in the synovial tissues from 36 FJOA patients and 10 healthy controls. The human synovial fibroblasts of FJOA were isolated and cultured followed by cell transfection. Then, cells were exposed to 10 ng/mL of IL-1ß to induce inflammatory response of synovial fibroblasts. The alternation on cell biological function in cell models was determined. The binding of miR-337-3p and SKP2 was predicted by StarBase, TargetScan, DIANA-microT and miRmap, and further verified by RIP assay and dual-luciferase reporter assay. Co-IP experiment and ubiquitination assay were used to display the binding of SKP2 and DUSP1 as well as the ubiquitination and degradation of DUSP1. After that, the FJOA rat model was established and miR-337-3p mimic or negative control was given to rats by tail vein injection. The pathological changes of synovial tissues, synovitis score, and inflammation level in rats were assessed. RESULTS: The low expressions of miR-337-3p and DUSP1 were noticed in the synovial tissues of FJOA patients and in IL-1ß-induced synovial fibroblasts, and highly expressed p-p38 MAPK was noticed. Upregulation of miR-337-3p/DUSP1 or downregulation of SKP2 inhibited IL-1ß-induced proliferation and inflammatory response of synovial fibroblasts. SKP2 was the target gene of miR-337-3p, and SKP2 induced the ubiquitination and degradation of DUSP1. MiR-337-3p exerted a protective effect on FJOA rats by alleviating damage of rat synovial tissues, promoting cell apoptosis and repressing inflammatory response. CONCLUSION: MiR-337-3p plays a protective role in FJOA by negatively targeting SKP2 to suppress DUSP1 ubiquitination and inactivate the p38 MAPK pathway.

hsa_circ_0006916 promotes hepatocellular carcinoma progression by activating the miR-337-3p/STAT3 axis.

BACKGROUND: Circular RNAs (circRNAs) are thought to be involved in the development of various malignancies. The expression and function of hsa_circ_0006916, a newly identified circRNA, in hepatocellular carcinoma remain unclear. METHODS: Quantitative RT-PCR was used to detect hsa_circ_0006916 in hepatocellular carcinoma. In vitro function assays were conducted to explore growth and invasion of hepatocellular carcinoma cells. Next, the mechanism of hsa_circ_0006916 function in hepatocellular carcinoma was determined by luciferase reporter and RIP assays. RESULTS: Hsa_circ_0006916 was substantially overexpressed in hepatocellular carcinoma tissues and cells. High levels of hsa_circ_0006916 in hepatocellular carcinoma patients were associated with advanced clinical characteristics. Down-regulation of hsa_circ_0006916 decreased the growth and invasion of hepatocellular carcinoma cells in vitro. The results suggested that hsa_circ_0006916 acted as a sponge of miR-337-3p and had an important functional use in the regulation of STAT3 levels in hepatocellular carcinoma cells. Moreover, miR-337-3p inhibition or STAT3 overexpression abolished the effect of hsa_circ_0006916 suppression on the progression of hepatocellular carcinoma cells. CONCLUSIONS: Our data suggest a novel hsa_circ_0006916/miR-337-3p/STAT3 axis in hepatocellular carcinoma, and provide a new target for treatment.

Inhibition of miR-337-3p involved in the protection of CoCl2 -induced injury in PC12 cells via activating JAK2/STAT3 signaling pathway.

OBJECTIVE: To investigate the possibility of microRNA (miR)-337-3p in the protection of hypoxia-induced injury in PC12 cells via modulating the JAK2/STAT3 signaling pathway. METHODS: Dual-luciferase reporter assay analyzed the relationship between the miR-337-3p and JAK2. PC12 cells were divided into normal, CoCl2 , CoCl2 + NC, CoCl2 + inhibitors, CoCl2 + JAK2, and CoCl2 + mimics + JAK2 groups. Then, PC12 cell viability and apoptosis were measured by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) and Annexin-V-fluorescein isothiocyanate/propidium iodide methods. Quantitative real-time polymerase chain reaction and Western blot analysis were used to determine expressions. Besides, the intracellular reactive oxygen species (ROS) was examined by dichloro-dihydro-fluorescein diacetate (DCFH-DA) while the mitochondrial membrane potential (MMP) by using JC-1. RESULTS: The negative targeting relationship between miR-337-3p and JAK2 was confirmed. When compared with the normal group, miR-337-3p was increased while JAK2 and STAT3 were decreased in CoCl2 -induced PC12 cells, with decreased cell viability. Moreover, either miR-337-3p inhibitor or JAK2 overexpression could partially reverse CoCl2 -induced decrease in PC12 cell viability. Besides, CoCl2 could also trigger PC12 cell apoptosis by increasing cleaved caspase 3 and Bax but decreasing Bcl-2 and Bcl-XL, which, however, were abolished with the transfection of miR-337-3p inhibitors or lentivirus transfection to activate JAK2. Compared with the CoCl2 group, the average of fluorescent signals of ROS in the CoCl2 + inhibitors group and the CoCl2 + JAK2 group was lower, while the activities of superoxide dismutase, catalase, glutathione peroxidase, and total anti-oxidative capacity were higher, together with an increase in MMP. CONCLUSION: Inhibiting miR-337-3p could activate the JAK2/STAT3 signaling pathway to suppress CoCl 2 -induced cytotoxicity and apoptosis and ameliorate oxidative stress and MMP in PC12 cells.

LncRNA CRNDE promotes hepatocellular carcinoma progression by upregulating SIX1 through modulating miR-337-3p.

BACKGROUND: Long noncoding RNA (lncRNA) is emerging as a vital regulator in various cancers. Recently, it was found that lncRNA colorectal neoplasia differentially expressed (CRNDE) plays an oncogenic role, promoting cell proliferation and migration in hepatocellular carcinoma (HCC). However, the underlying regulatory mechanism of lncRNA CRNDE remains unclear. METHODS: The expression levels of lncRNA CRNDE and miR-337-3p were analyzed by real-time polymerase chain reaction, and sineoculis homeobox homolog 1 (SIX1) expression was determined by Western blot analysis. RNA pull-down, luciferase and Western blot analysis assays were used to examine the target relationship between lncRNA CRNDE and miR-337-3p as well as between miR-337-3p and SIX1. The functional effects of lncRNA CRNDE and miR-337-3p were examined in vitro by using cell viability, colony formation, wound scratch, transwell assays, and in vivo in a xenograft tumor mouse model. RESULTS: LncRNA CRNDE was overexpressed in tumor tissues of patients with HCC. LncRNA CRNDE downregulation significantly suppressed cell proliferation and migration. Mechanistic investigations demonstrated that lncRNA CRNDE interacted with miR-337-3p and decreased its expression, thereby increasing the protein expression of miR-337-3p's target, SIX1. In addition, in vivo experiments using a xenograft tumor mouse model revealed that lncRNA CRNDE served as an oncogene, partly through sponging miR-337-3p and upregulating SIX1 in HCC. CONCLUSIONS: In this study, we report a newly identified regulatory mechanism lncRNA CRNDE/miR-337-3p/SIX1 axis, suggesting a promising therapeutic target in HCC.

Circ_ZNF124 promotes non-small cell lung cancer progression by abolishing miR-337-3p mediated downregulation of JAK2/STAT3 signaling pathway.

BACKGROUND: Previous genome-wide transcriptome profiling found circ_ZNF124 was highly expressed in lung adenocarcinoma, however, the role of circ_ZNF124 in non-small cell lung cancer (NSCLC) is still unknown. The purpose of this study was to investigate the role and molecular mechanism of circ_ZNF124 in NSCLC development. METHODS: The expression of circ_ZNF124, miR-337-3p and JAK2 (Janus Kinase 2) in lung cancer cell lines and normal epithelial cells were detected by qRT-PCR (quantitative real-time PCR). siRNA was used to knockdown circ_ZNF124 expression in cells. The effects of circ_ZNF124 in NSCLC cells were determined by cell growth, cell migration, cell cycle analysis and colony formation. Bioinformatics analysis, RNA immunoprecipitation, luciferase assay and western blots were used to study the molecular mechanism of circ_ZNF124 in NSCLC. RESULTS: The results showed that circ_ZNF124 expression was highly upregulated in NSCLC cells than in normal epithelial cells. Knockdown of circ_ZNF124 by using siRNA significantly decreased cell growth, promoted cell cycle arrested in sub-G1 phase, impaired cell migration and colony formation. Bioinformatic analysis discovered that miR-337-3p was a direct target of circ_ZNF124. In contrast to circ_ZNF124, miR-337-3p expression was significantly downregulated in NSCLC cells. Biotin labeled circ_ZNF124 immunoprecipitation and luciferase assay showed that miR-337-3p could directly bind to and affect circ_ZNF124 activity. The regulation of circ_ZNF124 on miR-337-3p was also investigated. Further analysis showed that despite STAT3 (signal transducer and activator of transcription 3), JAK2 was also a target of miR-337-3p, overexpression of miR-337-3p greatly downregulated JAK2, STAT3 and JAK2/STAT3 downstream regulated oncogenes HIF1a (Hypoxia-inducible factor 1-alpha), BCL2 (B cell lymphoma 2) and c-FOS expression, however, the roles of miR-337-3p in JAK2/STAT3 signaling pathway were greatly inhibited in the presence of circ_ZNF124. CONCLUSION: In NSCLC, highly expressed circ_ZNF124 promoted the activation of JAK2/STAT3 signaling pathway by acting as a sponge of miR-337-3p, thus promoting the occurrence and development of NSCLC. Circ_ZNF124 could be a potential biomarker or target for the treatment of NSCLC patients in the future.

Enhancement of the efficiency of oocyte vitrification through regulation of histone deacetylase 6 expression.

OBJECTIVE: Successful oocyte vitrification (OV) is critical for cryopreservation of the oocytes from female patients with infertility, polycystic ovaries, and gynecologic cancers. Recent evidence suggests that relatively low levels of histone acetylation are critical for maintenance of the maturation capacity of cryopreserved oocytes. However, previous studies have only demonstrated a key role of histone deacetylases (HDAC) 1 and 2 in the cryopreservation of oocytes. METHODS: In this study, we investigated the role of HDAC6 in these settings. We found that mouse oocytes with low HDAC6 levels decreased survival rate, cleavage rate, and blastocyst rate after OV. Bioinformatics analyses were used to predict HDAC6-targeting microRNAs (miRNAs), while the functional binding of miRNAs to HDAC6 mRNA was evaluated by a dual luciferase reporter assay. RESULTS: Among all HDAC6-targeting miRNAs, we detected expression of miR-558, miR-527, and miR-762 in mouse oocytes. Specifically, we found that only miR-762 significantly inhibited protein translation of HDAC6 via binding to the 3'-UTR of the HDAC6 mRNA. Transfection of oocytes with HDAC6 or antisense of miR-762 significantly increased the survival rate, the cleavage rate, and blastocyst rate after OV. CONCLUSION: As a result, our data suggest that induction of HDAC6 levels by miR-762 suppression may improve the current protocol for OV.

MicroRNAs in endometrial cancers from black and white patients.

OBJECTIVE: Previous studies have identified differences in gene mutations among endometrial cancers from whites and blacks suggesting that differences in tumor biology may explain racial disparities in patient outcome. Micro RNAs (miRNAs) have emerged as regulators of transcript expression and their aberrant expression has been discovered in many diseases, including endometrial cancer. We performed quantitative polymerase chain reaction-based analysis in a set of endometrial cancers to identify whether there are racial differences in miRNA expression. STUDY DESIGN: Tumor cells from 50 stage-I endometrioid endometrial cancer specimens from 41 white and 9 black patients were prepared by laser microdissection and miRNA extracts were analyzed using TaqMan (Life Technologies, Carlsbad, CA) low-density arrays. Statistically significant, differentially expressed miRNAs between blacks and whites were identified using multidimensional scaling, Wilcoxon testing, and analysis of variance. RESULTS: There were no global differences in miRNA expression between endometrial cancers from 41 white and 9 black patients. To minimize potential bias introduced by unbalanced sample size, we performed a subset analysis with stage- and histology-matched specimens from 9 whites and 9 blacks that identified 18 differentially abundant miRNAs (>2-fold at P < .005). Quantitative polymerase chain reaction validated miRNA-337-3p in an independent set of endometrial cancer specimens from 23 white and 24 black women. There were no racial differences in hsa-miR-337-3p expression in normal endometrium. CONCLUSION: These data indicate that hsa-mir-337-3p is more frequently down-regulated in endometrial cancers from whites compared to blacks. Future studies are focused on determining the phenotypic impact of miR-337-3p and whether its differential expression is associated with clinical outcome.

A review on expression and regulatory mechanisms of miR-337-3p in cancer.

A group of diseases generally referred to as cancer represents a serious threat to people's health all over the world and has a significant negative influence on every aspect of the lives of patients. The development of cancer is influenced by several environmental, genetic, and epigenetic factors. MicroRNAs (miRNAs), a class of non-coding RNAs, can alter the expression of genes involved in cell proliferation, migration, metastasis, and apoptosis, lead to the pathogenesis of cancer. Additionally, several effectors modify miRNAs directly, including methylation, circular RNAs, and long non-coding RNAs (lncRNAs). In this review, we have explained the role of mir-337-3p in the pathways related to the pathogenesis of different cancers. Studying the functional role of miR-337-3p is necessary for detecting novel molecules as tumor markers and discovering novel targets for cancer treatment.Communicated by Ramaswamy H. Sarma.

Long non-coding RNA HOXA11-AS regulates ischemic neuronal death by targeting miR-337-3p/YBX1 signaling pathway: protective effect of dexmedetomidine.

Cerebral ischemia/reperfusion (I/R) is a common neurological disease. Homeobox A11 antisense RNA (HOXA11-AS), a long non-coding RNA (lncRNA), has been demonstrated as an important regulator in diverse human cancers. However, its function and regulatory mechanism in ischemic stroke remains largely unknown. Dexmedetomidine (Dex) have received wide attraction because of its neuroprotective effects. This study aimed to explore the possible link between Dex and HOXA11-AS in protecting neuronal cells from by ischemia/reperfusion-induced apoptosis. We used oxygen-glucose deprivation and reoxygenation (OGD/R) in mouse neuroblastoma Neuro-2a cells and middle cerebral artery occlusion (MACO) mouse model to test the link. We found that Dex significantly alleviated OGD/R-induced DNA fragmentation, cell viability and apoptosis, and rescued the decreased HOXA11-AS expression after ischemic damage in Neuro-2a cells. Gain-/loss-of-function studies revealed that HOXA11-AS promoted proliferation, inhibited apoptosis in Neuro-2a cells exposed to OGD/R. Knockdown of HOXA11-AS decreased the protective effect of Dex on OGD/R cells. HOXA11-AS was found to transcriptionally regulate microRNA-337-3p (miR-337-3p) expression as evidenced by luciferase reporter assay, while miR-337-3p expression was upregulated following ischemia in vitro and in vivo. Besides, knockdown of miR-337-3p protected OGD/R-induced apoptotic death of Neuro-2a cells. Furthermore, HOXA11-AS functioned as a competing endogenous RNA (ceRNA) and competed with Y box protein 1 (Ybx1) mRNA for directly binding to miR-337-3p, which protected ischemic neuronal death. Dex treatment protected against ischemic damage and improved overall neurological functions in vivo. Our data suggest a novel mechanism of Dex neuroprotection for ischemic stroke through regulating lncRNA HOXA11-AS by targeting the miR-337-3p/Ybx1 signaling pathway, which might help develop new strategies for the therapeutic interventions in cerebral ischemic stroke.

Circ_0000228 Promotes Cervical Cancer Progression via Regulating miR-337-3p /TGFBR1 Axis.

Objective: This study aims to investigate the biological function of circular RNA (circRNA) circ_0000228 in the cervical cancer (CC). Materials and Methods: In this experimental study, the GSE113696 dataset was downloaded from the Gene Expression Omnibus (GEO). GEO2R was employed to obtain differentially expressed circRNA between CC tissues and matched paracancerous tissues. Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot were employed to detect circ_0000228, microRNA-337-3p (miR-337-3p ) and transforming growth factor, beta receptor I (TGFBR1) expression levels in the CC tissues and cells. Following gain-of-function and loss-of-function models establishment, CCK-8 and BrdU tests were conducted to examine cell proliferation. Transwell experiment was executed to examine CC cells migration and invasion. A lung metastasis model was utilized to determine the ability of circ_0000228 on the lung metastasis. Bioinformatics analysis, dual-luciferase reporter experiment and RNA immunoprecipitation (RIP) assay were applied to verify the targeting relationship among miR-337-3p , circ_0000228, and TGFBR1. Results: Circ_0000228 expression in the CC tissues and cells was up-modulated. Circ_0000228 overexpression markedly enhanced cell proliferation, migration, and invasion, while knocking down circ_0000228 remarkably repressed cell proliferation, migration, and invasion. MiR-337-3p could be adsorbed by circ_0000228. TGFBR1 was identified as a target gene of miR-337-3p that indirectly and positively modulated bycirc_0000228 in the CC cells. Conclusion: Circ_0000228 up-modulates TGFBR1 by targeting miR-337-3p to enhance CC cell proliferation, migration and invasion. Also, Circ_0000228 is a promising therapeutic target for the CC.

Circular RNA hsa_circ_0000117 accelerates the proliferation and invasion of gastric cancer cells by regulating the microRNA-337-3p/signal transducer and activator of transcription 3 axis.

Circular RNA hsa_circ_0000117 is reportedly increased in Gastric cancer (GC), however, its role is unexplored. Hsa_circ_0000117 expression and function in GC was investigated using standard cell phenotypic and expression assays. Pull-down and luciferase reporter assays also elucidated hsa_circ_0000117 mechanisms. In the present study, we observed increased hsa_circ_0000117 and signal transducer and activator of transcription 3 (STAT3) expression, while microRNA-337-3p (miR-337-3p) was decreased in GC cells. Depleted hsa_circ_0000117 decreased GC proliferation and invasion. Hsa_circ_0000117 was also identified as a miR-337-3p sponge. Also, STAT3 was identified as a miR-337-3p target. Similarly, rescue assays indicated STAT3 overexpression (or miR-337-3p inhibition) reversed hsa_circ_0000117 effects in GC progression. Thus, our data suggested hsa_circ_0000117 exhibited oncogene properties in combination with the hsa_circ_0000117/miR-337-3p/STAT3 axis in GC, potentially providing a new therapeutic target for GC.Abbreviations GC: gastric cancer; STAT3: Signal transducer and activator of transcription 3; circRNA: Circular RNA; miRNA: microRNA; DMEM: Dulbecco's modified Eagle's medium; FBS: fetal bovine serum; PVDF: polyvinylidene fluoride; CCK-8: Cell counting kit-8; qRT-PCR: Quantitative real-time PCR; SDS-PAGE: sodium dodecyl sulfate polyacrylamide gel electrophoresis; TNM: TNM Classification of Malignant Tumors; mTOR: mechanistic target of rapamycin; ANOVA: one-way analysis of variance.

Circular RNA circVRK1 suppresses the proliferation, migration and invasion of osteosarcoma cells by regulating zinc finger protein ZNF652 expression via microRNA miR-337-3p.

Circular RNA is an innovative kind of endogenous non-coding RNA, which could take part in tumorigenesis. Nonetheless, the potential molecular mechanisms of circVRK1 in the progression of osteosarcoma remain unresolved. In the current study, we initially investigated circVRK1 levels in osteosarcoma clinical samples and cell lines by qRT-PCR analysis and northern blot assay. RNase R treatments, RNA stability assay and nucleoplasmic separation assay were conducted to identify the characteristics of circVRK1. We adopted CCK-8, colony formation, wound-healing, and transwell assays to assess the biological effects of circVRK1 on the proliferation, migration, and invasiveness of osteosarcoma cells in vitro. We then constructed a xenograft model in nude mice to confirm the suppressive role of circVRK1 in vivo. Moreover, dual-luciferase reporter, RNA immunoprecipitation, and RNA pull-down assays were utilized to elucidate the underlying molecular mechanisms mediated by circVRK1. We demonstrated that circVRK1 was a stable circular transcript localized in the cytoplasm of osteosarcoma cells, and the down-regulation of circVRK1 in osteosarcoma tissues was related to poor outcome of patients. Meanwhile, over-expressed circVRK1 obviously restrained the growth, migration, and invasion of osteosarcoma in vitro and in vivo. Mechanistically, circVRK1 was assumed to be a microRNA sponge for miR-337-3p, and ZNF652 was the downstream gene of miR-337-3p. CircVRK1 overexpression or miR-337-3p knockdown accelerated ZNF652 expression, and up-regulated miR-337-3p efficiently abolished the promotion of ZNF652 induced by circVRK1. Moreover, rescue experiments have proved that circVRK1 inhibits the progression of osteosarcoma by modulating the miR-337-3p/ZNF652 axis. Therefore, we conclude that circVRK1 promotes ZNF652 expression by sponging miR-337-3p. CircVRK1 serves as a molecule sponge for miR-337-3p and mediates the ceRNA network to promote the expression of ZNF652, thus suppresses osteosarcoma proliferation, migration and invasion.

Circ_0000388 Exerts Oncogenic Function in Cervical Cancer Cells by Regulating miR-337-3p/TCF12 Axis.

Background: Cervical cancer (CC) is one of the most common cancers among women worldwide. Circular RNAs (circRNAs) are recently identified as important gene regulators with critical roles in cancer biology. In this study, we explored the effects of circ_0000388 on the malignant phenotypes of CC cells and its mechanism. Materials and Methods: Circ_0000388 expression and miR-337-3p expression in CC tissue samples were measured using quantitative real time polymerase chain reaction. CCK-8 was adopted to assess the effect of circ_0000388 on CC cell line proliferation. TUNEL assay was employed to probe the effect of circ_0000388 on apoptosis. Wound healing assay and transwell assay were conducted to detect the effect of circ_0000388 on migration and invasion. Further, interaction among circ_0000388, miR-337-3p, and TCF12 (transcription factor 12) was determined by bioinformatics analysis, RT-PCR, Western blot, RNA immunoprecipitation assay, and luciferase reporter assay. Results: Circ_0000388 expression in CC clinical samples was upregulated and this was correlated with unfavorable pathological indexes. Circ_0000388 remarkably enhanced the proliferation and metastasis of CC cells. Circ_0000388 overexpression dramatically impeded miR-337-3p expression and it was identified as a sponge of miR-337-3p. Furthermore, circ_00003888 also enhanced the TCF12 expression, while the effect could be reversed by co-transfection with miR-377-3p. Conclusions: Circ_0000388 was a novel oncogenic circRNA in CC, and promoted cancer progression via regulating miR-337-3p and TCF12, and could be potentially used as a diagnostic biomarker and therapy target.

MiR-337-3p lowers serum LDL-C level through targeting PCSK9 in hyperlipidemic mice.

BACKGROUND: Reducing serum low-density lipoprotein cholesterol (LDL-C) in hyperlipemia is recognized as an effective strategy to minimize the risk of atherosclerotic cardiovascular disease (ASCVD). MiR-337-3p has already been discovered to play regulatory roles in tumor proliferation and metastasis, adipocyte browning and ischemic brain injury, etc. However, the association between miR-337-3p and LDL-C is unknown. METHODS: Gene Expression Omnibus (GEO) dataset and two hyperlipidemic murine models were used to analyze the potential relationship between miR-337-3p and LDL-C. AAV-mediated liver-directed miRNA overexpression in high fat diet (HFD)-fed mouse model was used to examine the effect of miR-337-3p on LDL-C and WB/RT-PCR/ELISA/luciferase assays were used to investigate the underlying mechanism. RESULTS: The expressions of miR-337-3p were obviously lower in multiple hyperlipidemic mouse models and had a negative correlation with serum LDL-C levels. After confirming the effect of miR-337-3p on the improvement of serum LDL-C in vivo, we discovered PCSK9 might be a possible target of miR-337-3p, which was further proved by in vitro experiments. MiR-337-3p could directly interact with both the PCSK9 3'UTR and promoter to inhibit PCSK9 translation and transcription. Furthermore, the result from DiI-LDL uptake assay under the knockdown of PCSK9 demonstrated that miR-337-3p promoting the absorption of LDL-C in HepG2 cells was dependent on PCSK9, and the result from LDLR-/- mouse model indicated that miR-337-3p regulating LDL-C was dependent on PCSK9/LDLR pathway. CONCLUSION: We discovered a new function of miR-337-3p in regulating PCSK9 expression and LDL-C absorption, suggesting miR-337-3p might be a new therapeutic target for the development of antihyperlipidemic drug.

CircRNA_100565 contributes to cisplatin resistance of NSCLC cells by regulating proliferation, apoptosis and autophagy via miR-337-3p/ADAM28 axis.

Circular RNAs (circRNAs) have been revealed to involve in the chemoresistance of various cancers, including non-small cell lung cancer (NSCLC). Here, we further investigate the role of circRNA_100565 in NSCLC cisplatin (DDP) resistance. The expression of circRNA_100565 and microRNA (miR)-337-3p, and ADAM metallopeptidase domain 28 (ADAM28) mRNA was detected using quantitative real-time polymerase chain reaction. Cell viability and apoptosis were measured by cell counting kit-8 assay and flow cytometry, respectively. Western blot was used to detect the level of ADAM28 and autophagy-related protein. The interaction between miR-337-3p and circRNA_100565 or ADAM28 was confirmed by dual-luciferase reporter assay or pull-down assay. In vivo experiments were conducted via the murine xenograft model. We found CircRNA_100565 was up-regulated in NSCLC DDP-resistant tissues and cell lines, and its high expression was associated with shorter overall survival of NSCLC patients. CircRNA_100565 deletion mitigated DDP resistance, reflected by the suppression of proliferation and autophagy, the reduction of IC50 value, as well as enhancement of apoptosis in DDP-resistant NSCLC cells. MiR-377-3p was confirmed to directly bind to circRNA_100565 or ADAM28 3'-UTR. Moreover, circRNA_100565 indirectly regulated ADAM28 expression by sponging miR-377-3p in NSCLC cells. Additionally, circRNA_100565 deletion-induced sensitivity of NSCLC resistant cells to DDP could be remarkably attenuated by miR-377-3p inhibition or ADAM28 re-expression. Meanwhile, circRNA_100565 knockdown contributed to the anti-tumor effects of DDP on NSCLC in vivo.CONCLUSION: CircRNA_100565 was an independent prognostic factor for NSCLC patient survival, and enhanced the resistance of NSCLC cells to cisplatin by regulating cell proliferation, apoptosis and autophagy via miR-337-3p/ADAM28 axis, shedding light on the development of a novel therapeutic strategy to boost the effectiveness of NSCLC chemotherapy.

CircRNA_0092516 regulates chondrocyte proliferation and apoptosis in osteoarthritis through the miR-337-3p/PTEN axis.

The dysregulation of circular RNAs (circRNAs) has been identified in various human diseases. Here, we probed into the potential mechanism of circRNA_0092516 in osteoarthritis (OA). The expression of circRNA_0092516 was tested by quantitative real-time PCR. MTT, flow cytometry and western blot were applied to confirm the functions of circRNA_0092516 in vitro. Besides, RNA pull-down and dual-luciferase reporter gene experiments were applied to probe into the mechanism. circRNA_0092516 was raised in the tissues of OA patients and chondrocytes stimulated by IL-1ß. The potential mechanism analysis expounded that circRNA_0092516 bound to miR-337-3p, and the interference with circRNA_0092516 boosted chondrocyte proliferation and restrained cell apoptosis through the miR-337-3p/phosphatase and tensin homolog (PTEN) axis, thereby improving OA. In-vivo experiments expounded that circRNA_0092516 regulated cartilage production through miR-337-3p. Overall, our data expounded that the interference with circRNA_0092516 boosted chondrocyte proliferation and restrained cell apoptosis through the miR-337-3p/PTEN axis, eventually slowed down the progress of OA.

MiR-337-3p suppresses migration and invasion of breast cancer cells by downregulating ESRP1.

Breast cancer (BC) is a common malignant tumor in women, and a considerable number of studies show that aberrant expression of miRNA is correlated with BC development. By analyzing TCGA-BRCA database through bioinformatics method, this study disclosed that miR-337-3p was significantly low in BC tissue and might be a cancer inhibitor in BC. To explore the effect and potential mechanism of miR-337-3p in BC, qRT-PCR was used in this study to indicate that the expression of miR-337-3p was downregulated in BC cells. Then, the effects of miR-337-3p on BC cells were detected by western blot, Cell Counting Kit-8 (CCK-8), wound healing and Transwell assays. After upregulating miR-337-3p expression, the cell viability, migration, invasion and epithelial-mesenchymal transition (EMT) of BC cells were markedly inhibited while cell apoptosis remarkably increased. Besides, it was predicted and identified by bioinformatics analysis and dual-luciferase assay that ESRP1 was a target gene of miR-337-3p. Finally, the progression and EMT of BC cells were promoted after upregulating ESRP1 expression level. However, upregulating miR-337-3p as well as ESRP1 reduced the promotion on the malignant phenotype of BC cells. This result revealed that miR-337-3p could inhibit ESRP1 expression to perform its biological functions. In conclusion, it was illustrated in this study that miR-337-3p is a tumor-inhibitor of BC and plays its regulatory role via its downstream gene ESRP1.