Roles of lncLingo2 and its derived miR-876-5p in the acquisition of opioid reinforcement.

Recent studies found that non-coding RNAs (ncRNAs) played crucial roles in drug addiction through epigenetic regulation of gene expression and underlying drug-induced neuroadaptations. In this study, we characterized lncRNA transcriptome profiles in the nucleus accumbens (NAc) of mice exhibiting morphine-conditioned place preference (CPP) and explored the prospective roles of novel differentially expressed lncRNA, lncLingo2 and its derived miR-876-5p in the acquisition of opioids-associated behaviours. We found that the lncLingo2 was downregulated within the NAc core (NAcC) but not in the NAc shell (NAcS). This downregulation was found to be associated with the development of morphine CPP and heroin intravenous self-administration (IVSA). As Mfold software revealed that the secondary structures of lncLingo2 contained the sequence of pre-miR-876, transfection of LV-lncLingo2 into HEK293 cells significantly upregulated miR-876 expression and the changes of mature miR-876 are positively correlated with lncLingo2 expression in NAcC of morphine CPP trained mice. Delivering miR-876-5p mimics into NAcC also inhibited the acquisition of morphine CPP. Furthermore, bioinformatics analysis and dual-luciferase assay confirmed that miR-876-5p binds to its target gene, Kcnn3, selectively and regulates morphine CPP training-induced alteration of Kcnn3 expression. Lastly, the electrophysiological analysis indicated that the currents of small conductance calcium-activated potassium (SK) channel was increased, which led to low neuronal excitability in NAcC after CPP training, and these changes were reversed by lncLingo2 overexpression. Collectively, lncLingo2 may function as a precursor of miR-876-5p in NAcC, hence modulating the development of opioid-associated behaviours in mice, which may serve as an underlying biomarker and therapeutic target of opioid addiction.

Overexpression of circCDR1as drives oral squamous cell carcinoma progression.

BACKGROUND: Circular RNAs (circRNAs) mediate the progression of human cancers, including oral squamous cell carcinoma (OSCC). The aim of this study was to investigate the functions of circRNA CDR1 Antisense RNA (circCDR1as) in OSCC. Moreover, the relationships among circCDR1as, microRNA-876-5p (miR-876-5p) and Solute Carrier Family 7 Member 11 (SLC7A11) in OSCC development were explored. METHODS: Quantitative real-time polymerase chain reaction (qRT-PCR) was conducted to determine the expression of circCDR1as, miR-876-5p, and SLC7A11. Cell Counting kit-8 assay, cell colony formation assay, and 5-ethynyl-2'-deoxyuridine (EDU) assay were used to assess cell proliferation. Transwell assay was adopted for cell migration and invasion. RESULTS: CircCDR1as level was aberrantly elevated in OSCC tissues and cells. Overexpression of circCDR1as promoted autophagy, cell cycle, proliferation, and metastasis and repressed apoptosis in OSCC cells. CircCDR1as directly targeted miR-876-5p and miR-876-5p interacted with SLC7A11. MiR-876-5p overexpression reversed the effects of circCDR1as elevation on OSCC cell autophagy, cell cycle, growth, motility, and apoptosis. Inhibition of miR-876-5p aggravated the malignant behaviors of OSCC cells, while SLC7A11 silencing ameliorated the impacts. In addition, circCDR1as knockdown blocked tumor growth in vivo. CONCLUSION: CircCDR1as acted as an oncogene in OSCC progression through elevating SLC7A11 by targeting miR-876-5p.

A Novel circ_0104345/miR-876-3p/ZBTB20 Axis Regulates the Proliferation, Migration, Invasion, and Apoptosis of Breast Cancer Cells.

Breast cancer (BC) is one of the most common malignant tumors in women. CircRNA/miRNA/mRNA regulatory axes have been shown to be involved in the pathogenesis of BC. Here, we sought to analyze the functional mechanism of circ_0104345 in BC. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to detect the levels of circ_0104345, miR-876-3p and zinc finger and BTB domain containing 20 (ZBTB20) mRNA. Cell Counting Kit-8 (CCK8) and 5-ethynyl-2'-deoxyuridine (EdU) assays were used to test cell viability and proliferation, respectively. Cell migration was tested by wound healing assay, and cell invasion was examined by transwell assay. Tube formation ability was tested by angiogenesis assay. Flow cytometry was applied for cell apoptosis. Western blot assay was utilized to measure the protein expression. The relationship between miR-876-3p and circ_0104345 or ZBTB20 was identified by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. Xenografts in mice were conducted to analyze the effect of sh-circ_0104345 on tumor growth in vivo. Circ_0104345 and ZBTB20 were upregulated and miR-876-3p expression was decreased in BC. Circ_0104345 knockdown inhibited cell proliferation, migration, invasion, and enhanced cell apoptosis. MiR-876-3p was targeted by circ_0104345. MiR-876-3p depletion reversed the effects of circ_0104345 downregulation on the progression of BC cells. ZBTB20 was regulated by circ_0104345 through miR-876-3p. The effects of miR-876-3p on BC cell behaviors were restored by ZBTB20 increase. The results of in vivo experiments indicated that silencing of circ_0104345 blocked the growth of xenograft tumors. In this study, we demonstrated, for the first time, the crucial regulation of the new circ_0104345/miR-876-3p/ZBTB20 axis in the biological phenotypes of BC cells.

Hsa_circ_0097922 promotes tamoxifen resistance and cell malignant behaviour of breast cancer cells by regulating ACTN4 expression via miR-876-3p.

An increasing number of findings have verified the critical roles of circular RNAs (circRNAs) in human cancers, and chemotherapy resistance is a poor prognostic factor for breast cancer (BC). This study is designed to explore the function of hsa_circ_0097922 in the tamoxifen resistance of breast cancer. Hsa_circ_0097922, microRNA-876-3p (miR-876-3p), and alpha-actinin 4 (ACTN4) level were detected by real-time quantitative polymerase chain reaction (RT-qPCR). Cell survival, proliferation, apoptosis, migration and invasion were detected by Cell Counting Kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), and flow cytometry, wound healing and Transwell assays. Protein levels of proliferating cell nuclear antigen (PCNA), B-cell lymphoma-2 (Bcl-2), cleaved caspase 3, matrix metalloproteinase 9 (MMP9), and ACTN4 were determined using western blot assay. Using bioinformatics software, the binding between miR-876-3p and hsa_circ_0097922 or ACTN4 was predicted, followed by confirmation by RNA immunoprecipitation (RIP) and RNA pull-down assays. A xenograft tumour model in vivo analysed the biological role of hsa_circ_0097922 on BC tumour growth and drug resistance. Hsa_circ_0097922 and ACTN4 were increased, and miR-876-3p was decreased in tamoxifen resistance BC cells. Moreover, hsa_circ_0097922 knockdown can block BC cell malignant behaviour and tamoxifen resistance in vitro. Mechanically, hsa_circ_0097922 acted as a sponge of miR-876-3p to regulate ACTN4 expression. Hsa_circ_0097922 silencing increased the drug sensitivity of BC in vivo. Hsa_circ_0097922 might regulate BC cell malignant behaviour and tamoxifen resistance partly by regulating the miR-876-3p/ACTN4 axis, hinting at a promising therapeutic target for the BC treatment.

Hsa_circ_0043949 reinforces temozolomide resistance via upregulating oncogene ITGA1 axis in glioblastoma.

Temozolomide (TMZ) resistance limits its use in glioblastoma (GBM). Exosomes can carry circular RNAs (circRNAs) to regulate chemoresistance. To date, the role of exosomal hsa_circ_0043949 (circ_0043949) in GBM resistance to TMZ is unclear. Relative expression of circ_0043949 in clinical samples, GBM cell lines, and exosomes was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The half-maximal inhibitory concentration (IC50) of TMZ, cell proliferation, apoptosis, invasion, and migration were analyzed via MTT, EdU, flow cytometry, transwell, and wound-healing assays. Relative protein levels were evaluated by western blotting. Target relationship was predicted by bioinformatics analysis and validated by dual-luciferase reporter and RNA pull-down assays. Exosomes were isolated by ultracentrifugation and verified by transmission electron microscopy, nanoparticle tracking analysis (NTA), and western blotting. The effect of exosomal circ_0043949 on TMZ resistance was validated by xenograft assay. Higher expression of circ_0043949 was gained in TMZ-resistant GBM samples and cells. Inhibition of circ_0043949 reduced TMZ resistance via decreasing IC50 of TMZ, repressing proliferation, invasion, migration, and inducing apoptosis in TMZ-resistant GBM cells. Circ_0043949 mediated integrinalpha1 (ITGA1) expression via function as a miR-876-3p sponge. Circ_0043949 was also upregulated in TMZ-resistant GBM cells-derived exosomes, and exosomal circ_0043949 increased the resistance of TMZ-resistant GBM cells to TMZ in xenograft models. TMZ-resistant GBM cells-derived exosomal circ_0043949 promoted TMZ resistance via upregulating ITGA1 expression via sequestering miR-876-3p, offering a potential target for the treatment of TMZ resistance in GBM.

Circ_0016760 Serves as a Cancer Promoter in Non-small Cell Lung Cancer Through miR-876-3p/NOVA2 Axis.

Non-small cell lung cancer (NSCLC) is a serious threaten to human health globally. Circular RNAs (circRNAs) were testified to alter the progression of NSCLC. This work intended to investigate the functional role of circ_0016760 in NSCLC development and the potential mechanism. Expression of circ_0016760, microRNA (miR)-876-3p and NOVA alternative splicing regulator 2 (NOVA2) was determined via quantitative reverse transcription-PCT (qRT-PCR) or western blotting. Cell viability, clonogenicity and apoptosis were assessed by Cell Counting Kit-8 (CCK-8) assay, colony formation assay and flow cytometry, respectively. Transwell assay was performed to examine cell migration and invasion. Western blotting was also conducted to detect the levels of epithelial-to-mesenchymal transition (EMT)-related proteins. Role of circ_0016760 in vivo was evaluated via xenograft model assay. Moreover, the interaction between miR-876-3p and circ_0016760 or NOVA2 was verified by dual-luciferase reporter assay or RNA Immunoprecipitation (RIP) assay. Circ_0016760 and NOVA2 were upregulated, while miR-876-3p expression was decreased in NSCLC tissues and cells. Circ_0016760 depletion suppressed NSCLC cell proliferation and metastasis in vitro, as well as hampered tumor growth in vivo. Circ_0016760 acted as a sponge of miR-876-3p, and miR-876-3p could target NOVA2. Circ_0016760 might play vital roles in NSCLC by regulating miR-876-3p/NOVA2 axis. Circ_0016760 could promote the malignant development of NSCLC through miR-876-3p/NOVA2 axis, at least in part.

Circ_0062558 promotes growth, migration, and glutamine metabolism in triple-negative breast cancer by targeting the miR-876-3p/SLC1A5 axis.

BACKGROUND: Circular RNAs (circRNAs) have been reported to function as vital regulators in cancers, including triple-negative breast cancer (TNBC). This study aimed to explore the role of circ_0062558 in TNBC. METHODS: The real-time quantitative polymerase chain reaction (RT-qPCR) was conducted to quantify the expressions of circ_0062558, microRNA-876-3p (miR-876-3p), and solute carrier family 1 (neutral amino acid transporter), member 5 (SLC1A5) in TNBC tissues and cells. 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyl-2H-tetrazol-3-ium bromide (MTT), thymidine analog 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry, wound healing, and Transwell assays were employed for cell phenotype analyses. Protein expression was tested by western blot analysis. Dual-luciferase reporter was used to confirm the association among circ_0062558, miR-876-3p, and SLC1A5 in TNBC. Xenograft experiments were performed to elucidate the function of circ_0062558 in vivo. RESULTS: TNBC tissues and cells showed the higher level of circ_0062558 when compared with control samples. Downregulation of circ_0062558 inhibited proliferation, migration, invasion, and glutamine metabolism, while enhanced apoptosis of TNBC cells, and silencing of circ_0062558 also inhibited the growth of tumor in vivo. MiR-876-3p was confirmed as a target of circ_0062558, and circ_0062558 knockdown repressed TNBC cell malignant behaviors by increasing miR-876-3p. Furthermore, miR-876-3p inhibited malignant behaviors of TNBC cells by down-regulating SLC1A5, a newly identified target of miR-876-3p. CONCLUSION: Circ_0062558 promoted TNBC progression by enhancing proliferation, survival, migration, invasion, and glutamine metabolism via miR-876-3p/SLC1A5 axis, which was helpful for understanding the carcinogenic roles of circ_0062558.

CircVAPA exerts oncogenic property in non-small cell lung cancer by the miR-876-5p/WNT5A axis.

BACKGROUND: Non-small cell lung cancer (NSCLC) is one of the most fatal malignant tumors. Emerging studies have clarified the crucial roles of circular RNAs (circRNAs) in the tumorigenesis of cancers. CircVAPA was demonstrated to function in some human cancers. The present study aimed to investigate the role of circVAPA in NSCLC. METHODS: A quantitative real-time polymerase chain reaction was used to measure the expression of genes. Actinomycin D and RNase R were employed to examine the stability of circVAPA. Cell-counting kit-8, 5-ethynyl-2'-deoxyuridine, Transwell and sphere formation assays, and well as western blot analysis, were conducted to examine the changes of NSCLC cells in response to circVAPA knockdown. A luciferase reporter assay was conducted for the molecular mechanism. RESULTS: Our findings demonstrated high expression of circVAPA in tissues and cell lines of NSCLC. Knockdown of circVAPA had a suppressive effect on cell proliferation, migration, invasion and stemness, and also inhibited tumor growth in vivo. Mechanistically, circVAPA acted as a competing endogenous RNA to up-regulate WNT5A by sponging miR-876-5p. Moreover, circVAPA activated Wnt/ß-catenin signaling by up-regulation of WNT5A. Rescue assays showed that silencing of miR-876-5p or overexpression of WNT5A reversed the circVAPA knockdown-mediated inhibition on cellular processes in NSCLC. CONCLUSIONS: CircVAPA promotes aggressive phenotypes of NSCLC cells by the miR-876-5p/WNT5A axis activating Wnt/ß-catenin signaling.

miR-876-3p suppresses the progression of colon cancer and correlates the prognosis of patients.

BACKGROUND: miR-876-3p has been identified to be downregulated in colon cancer, implying the potential biological function in the progression and prognosis of colon cancer. The clinical significance and the biological function of miR-876-3p were investigated in this study to assess the potential of miR-876-3p in acting as a novel biomarker of the progression of colon cancer. METHODS: The expression of miR-876-3p in colon cancer was evaluated by RT-qPCR. The clinical significance of miR-876-3p was assessed by associated its expression level with the clinical features and prognosis of patients. The biological function of miR-876-3p was estimated by the CCK8 and Transwell assay in vitro. RESULTS: The significant downregulation of miR-876-3p was observed in colon cancer tissues and cells, which was closely associated with the lymph node metastasis status, TNM stage, and the perineural invasion of patients. miR-876-3p served as an independent indicator that was negatively associated with the prognosis of patients. In colon cancer cells, miR-876-3p showed significant inhibitory effects on cell proliferation, migration, and invasion, indicating its tumor suppressor role in the progression of colon cancer. CONCLUSION: miR-876-3p might be involved in colon cancer development, which provides a potential therapeutic target for colon cancer treatment.

Circ_0093887 upregulates CCND2 and SUCNR1 to inhibit the ox-LDL-induced endothelial dysfunction in atherosclerosis by functioning as a miR-876-3p sponge.

Circular RNAs (circRNAs) are widely expressed in mammals and act as regulatory targets in the atherogenesis. The objective of this study was to research the biological role and molecular mechanism of circ_0093887 in oxidized low-density lipoprotein (ox-LDL)-induced atherosclerosis (AS) of human aortic endothelial cells (HAECs). Cell viability detection was performed by CCK-8 assay. Inflammatory molecules were examined using ELISA. Flow cytometry was used to measure cell-cycle progression and cell apoptotic rate. Caspase 3 activity was determined using caspase 3 activity assay. The expression levels of circ_0093887, miR-876-3p, CCND2 and SUCNR1 were assayed by quantitative real-time polymerase chain reaction (qRT-PCR). Dual-luciferase reporter, RNA immunoprecipitation (RIP) and RNA pull-down assays were used for the target analysis. EdU assay, wound healing assay/transwell assay and tube formation assay were, respectively, used to assess the effects of circ_0093887/miR-876-3p axis on cell proliferation, migration and tube formation. Oxidized low-density lipoprotein inhibited cell viability and cell-cycle progression but induced the inflammatory response and cell apoptosis. Circ_0093887 was downregulated and miR-876-3p was upregulated in AS patients and ox-LDL-treated HAECs. Functionally, the overexpression of circ_0093887 abrogated the cell injury of HAEC exposed to ox-LDL. For the functional mechanism, we found that circ_0093887 was a sponge for miR-876-3p and miR-876 targeted CCND2 or SUCNR1. The reverted experiment indicated that the function of circ_0093887 was achieved by sponging miR-876-3p. Meanwhile, miR-876-3p inhibitor relieved the inhibitory regulation of circ_0093887 knockdown in cell proliferation, migration and tube formation. Downregulation of miR-876-3p also alleviated the ox-LDL-induced cell injury by upregulating the expression of CCND2 or SUCNR1. Furthermore, circ_0093887 was validated to regulate the levels of CCND2 and SUCNR1 via the sponge effect on miR-876-3p. The protective effects of circ_0093887 on HAECs from ox-LDL were also ​alleviated by repressing the CCND2 and SUCNR1 levels. These findings suggested that circ_0093887 protected HAEC against the ox-LDL-induced inflammatory and apoptotic damages by targeting the miR-876-3p/CCND2 or miR-876/SUCNRA axis. Circ_0093887 could act as a potential therapeutic biomarker for AS patients.

Circ-RNF111 aggravates the malignancy of gastric cancer through miR-876-3p-dependent regulation of KLF12.

BACKGROUND: The aberrant expression of circular RNAs (circRNAs) plays vital roles in the advancement of human cancers, including gastric cancer (GC). In this study, the functions of circRNA ring finger protein 111 (circ-RNF111) in GC were investigated. METHODS: Quantitative real-time polymerase chain reaction (qRT-PCR) assay was performed for the levels of circ-RNF111, microRNA-876-3p (miR-876-3p) and krueppel-like factor 12 (KLF12) mRNA. RNase R assay was conducted for the feature of circ-RNF111. Cell Counting Kit-8 (CCK-8) assay, colony formation assay, wound-healing assay, and transwell assay were applied for cell viability, colony formation, migration, and invasion, respectively. Flow cytometry analysis was used to analyze cell apoptosis and cell cycle process. The glycolysis level was examined using specific commercial kits. Western blot assay was carried out to measure the protein levels of hexokinase 2 (HK-2) and KLF12. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were employed to verify the combination between miR-876-3p and circ-RNF111 or KLF12. Murine xenograft model was constructed for the role of circ-RNF111 in vivo. Immunohistochemistry (IHC) was used for KLF12 level. RESULTS: Circ-RNF111 was higher expressed in GC tissues and cells than normal tissues and cells. Silencing of circ-RNF111 restrained cell viability, colony formation, migration, invasion, cell cycle process and glycolysis and induced apoptosis in GC cells in vitro. Circ-RNF111 positively regulated KLF12 expression via absorbing miR-876-3p. MiR-876-3p downregulation reversed the impacts of circ-RNF111 silencing on GC cell malignant phenotypes. MiR-876-3p overexpression repressed GC cell growth, metastasis and glycolysis, inhibited apoptosis and arrested cell cycle, while KLF12 elevation weakened the effects. Besides, circ-RNF111 knockdown inhibited tumor growth in vivo. CONCLUSION: Circ-RNF111 knockdown relieved the development of GC by regulating miR-876-3p/KLF12 axis.

MCM3AP-AS1/miR-876-5p/WNT5A axis regulates the proliferation of prostate cancer cells.

BACKGROUND: Although the fact that long non-coding RNA MCM3AP antisense RNA 1 (MCM3AP-AS1) is oncogenic in several cancers is well documented, very few researchers investigate its expression and function in prostate cancer. METHODS: Paired prostate cancer samples were selected, and expressions of MCM3AP-AS1, miR-876-5p and WNT5A were examined by qRT-PCR. MCM3AP-AS1 shRNA was transfected into LNCaP and PC-3 cell lines, and then the proliferative activity and apoptosis of cancer cells were detected by CCK-8 assay, EdU assay and flow cytometry analysis, respectively. qRT-PCR and Western blot were used to analyze the changes of miR-876-5p and WNT5A. Luciferase reporter gene assay was employed to determine the regulatory relationship between miR-876-5p and MCM3AP-AS1, miR-876-5p and WNT5A. RESULTS: MCM3AP-AS1 was significantly up-regulated in cancerous tissues of prostate cancer samples, positively correlated with the expression of WNT5A, while negatively related with miR-876-5p. After transfection of MCM3AP-AS1 shRNA into prostate cancer cells, the proliferative ability of cancer cells was signally inhibited, but the apoptosis of cancer cells was increased. MCM3AP-AS1 shRNA could reduce the expression of WNT5A on both mRNA and protein levels. Besides, MCM3AP-AS1 was identified as a sponge of miR-876-5p. WNT5A was validated as a target gene of miR- 876-5p. CONCLUSION: MCM3AP-AS1 is abnormally up-regulated in prostate cancer tissues and can modulate the proliferation and apoptosis of prostate cancer cells, which has the potential to be the "ceRNA" to regulate the expression of WNT5A by targeting miR-876-5p.

BRD8, which is negatively regulated by miR-876-3p, promotes the proliferation and apoptosis resistance of hepatocellular carcinoma cells via KAT5.

Bromodomain-containing 8 (BRD8), which belongs to the histone acetyl transferase (HAT) complex, functions as a driver in colorectal cancer. However, the role of BRD8 and its related regulatory mechanisms in hepatocellular carcinoma (HCC) remain unexplored. In this study, we found that the level of BRD8 mRNA in HCC was prominently higher than that in nontumor tissues. Furthermore, immunohistochemistry analysis indicated that BRD8 protein expression was upregulated in HCC compared to noncancerous tissues. The positive expression of BRD8 was closely associated with HBV infection, a tumor size ≥5 cm and an advanced TNM stage. Moreover, HCC patients with an elevated expression of BRD8 had an obvious poorer survival rate. Functionally, BRD8 knockdown markedly reduced the proliferation of Hep3B and Huh7 cells. Depletion of BRD8 obviously induced the apoptosis of HCC cells. Conversely, BRD8 overexpression promoted the proliferation and apoptosis resistance of Huh7 cells. Lysine acetyltransferase 5 (KAT5) expression was significantly upregulated in HCC tissues. In addition, BRD8 knockdown obviously reduced the level of KAT5 protein and the mRNA expression of KAT5-induced genes in both Hep3B and Huh7 cells. KAT5 knockdown showed similar effects as BRD8 silencing on HCC cell proliferation and apoptosis. The expression of miR-876-3p was downregulated and inversely correlated with the BRD8 mRNA level in HCC tissues. The expression of BRD8 protein in HCC cells was reduced by the overexpression of miR-876-3p and enhanced by the knockdown of miR-876-3p. A luciferase reporter assay demonstrated that BRD8 was a direct target of miR-876-3p. Notably, in HCC cells, the ectopic expression of miR-876-3p inhibited proliferation and induced apoptosis. In conclusion, BRD8, which was negatively regulated by miR-876-3p, facilitated proliferation and inhibited apoptosis in HCC cells by modulating KAT5.

SNHG17 drives malignant behaviors in astrocytoma by targeting miR-876-5p/ERLIN2 axis.

BACKGROUND: Astrocytoma is a common tumor type in primary central nervous system and has a high death rate around the world. Aberrant expression of long non-coding RNAs (lncRNAs) has been introduced by emerging studies to result in the development of diverse cancers. METHODS: RT-qPCR examined the expression of SNHG17, miR-876-5p and ERLIN2, and western blot evaluated ERLIN2 protein level. RNA pull down and luciferase reporter assays illustrated the relationships between SNHG17 and its downstream molecules. RESULTS: SNHG17 was up-regulated in astrocytoma cells. Moreover, SNHG17 silence could repress the proliferation, migration and invasion of astrocytoma cells. Besides, miR-876-5p was selected out as a downstream molecule of SNHG17 in astrocytoma. ERLIN2 was determined to be targeted by miR-876-5p. ERLIN2 mRNA and protein levels were lessened by miR-876-5p overexpression and SNHG17 silence. Additionally, miR-876-5p overexpression decelerated the biological processes of astrocytoma cells, so did ERLIN2 knockdown. More importantly, the impacts of SNHG17 down-regulation on the malignant behaviors of astrocytoma cells were counteracted by overexpressed ERLIN2 or inhibited miR-876-5p. CONCLUSIONS: SNHG17 could induce the progression of astrocytoma by sponging miR-876-5p to elevate the expression of ERLIN2. This study indicated that SNHG17 has a high potential to be a therapeutic target for astrocytoma.

Long Non-coding RNA MINCR Regulates miR-876-5p/GSPT1 Axis to Aggravate Glioma Progression.

Emerging evidence underlined the crucial roles played by long non-coding RNAs (lncRNAs) in glioma. MINCR has been reported in multiple malignancies. Here, we studied its function and potential mechanism in glioma, which remain unclear. Gene expressions were analyzed by qRT-PCR assay. Both in vitro and in vivo assays were conducted to evaluate the cellular function of MINCR in glioma. The subcellular situation of MINCR was detected by subcellular fractionation and FISH assays. Luciferase reporter, RNA pull-down and RNA immunoprecipitation (RIP) assays were combined to investigate potential mechanisms of relevant genes. MINCR was up-regulated in glioma. MINCR depletion markedly refrained glioma cell proliferation, migration and invasion via sponging miR-876-5p. MiR-876-5p suppressed the malignant behaviors of glioma via binding to GSPT1. MINCR shared the binding sites with the 3'-untranslated region of GSPT1 and prevented the binding of miR-876-5p to GSPT1 mRNA, thus up-regulating the level of GSPT1. Moreover, miR-876 inhibition and GSPT1 up-regulation counteracted the functional effect induced by silencing MINCR on glioma progression. Our findings uncovered that MINCR might aggravated glioma cell proliferation and migration via acting as competing endogenous RNA (ceRNA), indicating prospective novel therapeutic target for glioma.

MicroRNA-876-5p represses the cell proliferation and invasion of colorectal cancer through suppressing YAP signalling via targeting RASAL2.

Aberrant expression of microRNA-876-5p (miR-876-5p) is implicated in the progression of multiple human cancers. However, the potential role of miR-876-5p in colorectal cancer remains poorly understood. The purpose of the current study was to investigate the potential role of miR-876-5p in colorectal cancer. miR-876-5p expression was significantly downregulated in colorectal cancer tissues and cell lines compared with normal controls. Gain-of-function assays revealed that miR-876-5p overexpression effectively repressed the malignant behaviours of colorectal cancer cells, including cell proliferation, colony formation, and invasion. Bioinformatics analysis predicted that RAS protein activator like 2 (RASAL2), a potential oncogene for colorectal cancer, is a putative miR-876-5p target gene. A luciferase reporter assay confirmed that miR-876-5p directly binds to the 3'-untranslated region (UTR) of RASAL2. Furthermore, both RASAL2 messenger RNA (mRNA) and protein expression were negatively modulated by miR-876-5p in colorectal cancer cells. Notably, there was an inverse correlation between miR-876-5p and RASAL2 expression in colorectal cancer tissue specimens. Moreover, miR-876-5p was involved in regulating the activation of Yes-associated protein (YAP) signalling through inhibiting RASAL2. However, the miR-876-5p-mediated antitumour effect on colorectal cancer cells was partially reversed by restoring RASAL2 expression. Notably, miR-876-5p upregulation impeded the tumour growth of colorectal cancer cells in vivo in nude mice. Overall, these results demonstrated that miR-876-5p exerts an antitumour function in colorectal cancer by targeting RASAL2 to suppress YAP signalling activation. These findings highlight the importance of the miR-876-5p/RASAL2/YAP axis in colorectal cancer progression and suggest that miR-876-5p is a potential therapeutic target for treating colorectal cancer.

MicroRNA-876-5p inhibits cell proliferation, migration and invasion by targeting c-Met in osteosarcoma.

Recently, aberrant expression of miR-876-5p has been reported to participate in the progression of several human cancers. However, the expression and function of miR-876-5p in osteosarcoma (OS) are still unknown. Here, we found that the expression of miR-876-5p was significantly down-regulated in OS tissues compared to para-cancerous tissues. Clinical association analysis indicated that underexpression of miR-876-5p was positively correlated with advanced clinical stage and poor differentiation. More importantly, OS patients with low miR-876-5p level had a significant shorter overall survival compared to miR-876-5p high-expressing patients. In addition, gain- and loss-of-function experiments demonstrated that miR-876-5p restoration suppressed whereas miR-876-5p knockdown promoted cell proliferation, migration and invasion in both U2OS and MG63 cells. In vivo studies revealed that miR-876-5p overexpression inhibited tumour growth of OS in mice. Mechanistically, miR-876-5p reduced c-Met abundance in OS cells and inversely correlated c-Met expression in OS tissues. Herein, c-Met was recognized as a direct target of miR-876-5p using luciferase reporter assay. Notably, c-Met restoration rescued miR-876-5p attenuated the proliferation, migration and invasion of OS cells. In conclusion, these findings indicate that miR-876-5p may be used as a potential therapeutic target and promising biomarker for the diagnosis and prognosis of OS.

MiR-876-3p regulates cisplatin resistance and stem cell-like properties of gastric cancer cells by targeting TMED3.

BACKGROUND AND AIM: Gastric cancer (GC), a prevalent tumor, exerts a major economic burden, and we aimed to explore miR-876-3p's effects on GC and related mechanisms. METHODS: Cell viability was analyzed via CCK-8 and colony formation assay. Stem cell-like properties were examined via spheroid colony formation assay. mRNA abundance of key genes was analyzed via quantitative polymerase chain reaction. Protein level of TMED3 and stem cell markers was examined by western blot. TargetScan, luciferase, and biotin-miRNA pulldown assay were used to identify miR-876-3p's target. RESULTS: MiR-876-3p was downregulated in GC, and its mRNA level had negative relationship with cisplatin resistance of GC. Moreover, decreased miR-876-3p expression level suggested poor prognosis of GC patients. MiR-876-3p inhibited drug resistance of cisplatin-resistant cell line SGC-7901/DDP and MKN-45/DDP, as shown by decreased cell viability, IC50 , and colony formation ability. MiR-876-3p inhibited stem cell-like features and downregulated the expressions of Sox-2, Oct-4, CD133, and CD44 in GC cells. Luciferase and biotin-miRNA pulldown assay confirmed that TMED3 was miR-876-3p's direct target. TMED3 siRNA inhibited miR-876-3p's effects on cisplatin resistance and stem cell-like features of SGC-7901/DDP cells. CONCLUSION: MiR-876-3p enhanced cisplatin sensitivity and restricted stem cell-like features of GC through targeting TMED3.

FBXL19-AS1 promotes cell proliferation and inhibits cell apoptosis via miR-876-5p/FOXM1 axis in breast cancer.

As the most common cancer and one of the leading causes of cancer-associated mortality, breast cancer continues to need more key molecules to regulate its progression. F-box and leucine-rich repeat protein 19 antisense RNA 1 (known as FBXL19-AS1) is a long non-coding RNA (lncRNA) which has been reported as an oncogene in several types of human cancers. However, the specific downstream targets of FBXL19-AS1 remain unknown. In this study, we set out to find more reliable downstream molecules of FBXL19-AS1 in breast cancer. FBXL19-AS1 was expressed at a high level in breast cancer cells. Loss-of-function experiments revealed that silencing FBXL19-AS1 could impair cell proliferation and induce cell apoptosis in breast cancer. In addition, the location of FBXL19-AS1 in the cytoplasm was detected by fluorescent in situ hybridization assay, while FBXL19-AS1 regulated the expression of Forkhead box M1 (FOXM1) by directly absorbing miR-876-5p. Through rescue assays, it was observed that FOXM1 overexpression recovered the inhibited tumor growth caused by FBXL19-AS1 downregulation. We affirmed the function of FBXL19-AS1 in breast cancer and described the mechanism of the FBXL19-AS1/miR-876-5p/FOXM1 axis. The current work presents the molecular mechanism which underlies FBXL19-AS1 in breast cancer and suggests a comprehensive, feasible FBXL19-AS1-mediated therapeutic approach for treating breast cancer.

MiR-876-5p modulates head and neck squamous cell carcinoma metastasis and invasion by targeting vimentin.

BACKGROUND: Local or distant metastasis remains the main course of death in head and neck squamous cell carcinoma (HNSCC) patients. MicroRNAs (miRNAs) have been implicated in metastasis of HNSCC, but the mechanisms of their action are mainly undocumented. Through public head and neck cancer miRNA expression datasets, we found that miR-876-5p was a novel potential tumor suppressor targeting HNSCC metastasis. METHODS: Clinical significance and mechanism of miR-876-5P was systematically analyzed in HNSCC. Quantitative RT-PCR was used to evaluate miR-876-5p levels in HNSCC cell lines and in 20 pairs of HNSCC with associated regional nodal metastases and HNSCC without metastatic primary tumors. Scratch and invasion assays were evaluated to determine the role of miR-876-5p in the regulation of HNSCC cell migration and invasion, respectively. Western blotting was used to investigate the mechanism by which miR-876-5p suppresses HNSCC cell invasion and migration. Luciferase assays were performed to assess miR-876-5p binding to the vimentin gene. The animal model was used to support the in vitro experimental findings. RESULTS: MiR-876-5p mimics inhibited HNSCC cell migration and invasion. Vimentin protein and mRNA levels were decreased in the miR-876-5p mimics group but increased in the miR-876-5p inhibitors group, which demonstrated that miR-876-5p inhibits vimentin expression in HNSCC cells. By directly targeting the vimentin 3'-UTR, we used dual-luciferase reporter assays to verify that vimentin is a functional downstream target of miR-876-5p. Importantly, increased vimentin expression promoted cell migration and invasion, and co-transfection with miR-876-5p mimics and vimentin restored cell aggressiveness to the original level. Moreover, miR-876-5p overexpression significantly downregulated vimentin expression level and inhibited the distal metastasis of HNSCC cells in vivo. CONCLUSIONS: miR-876-5p, which functions as a tumor suppressor in HNSCC, inhibits metastasis by targeting vimentin and provides a novel therapeutic target for HNSCC treatment.