The circular RNA circSLC16A10 alleviates diabetic retinopathy by improving mitochondrial function via the miR-761-5p/MFN2 axis.

It has been demonstrated that circular RNAs (circRNAs) are associated with the development of diabetic retinopathy (DR). Nevertheless, the function of circSLC16A10 in the development of DR remains unclear. In order to investigate the role of circSLC16A10, we employed cell and animal models of DR. An analysis of a public database revealed that hsa_circSLC16A10 was expressed at lower levels in DR patients than in diabetic patients without DR or healthy controls. Additionally, the level of hsa_circSLC16A10 was lower in high glucose (HG)-exposed ARPE-19 cells and diabetic mice. hsa_circSLC16A10 was observed to be mainly distributed in the cytoplasm. Moreover, overexpression of hsa_circSLC16A10 alleviated HG-induced endoplasmic reticulum stress and cell apoptosis in vitro. Furthermore, overexpression of hsa_circSLC16A10 ameliorated HG-induced mitochondrial dysfunction, as evidenced by improvements in mitochondrial structure and function. hsa_circSLC16A10 acted as a hsa-miR-761-5p sponge to increase MFN2 expression. MFN2 knockdown or hsa-miR-761-5p overexpression partially reversed the protective effect of hsa_circSLC16A10 in vitro. The protective effect of mmu_circSLC16A10 against DR was confirmed in an animal model of DR. These findings indicate that circSLC16A10 may regulate DR progression by improving mitochondrial function via the miR-761-5p/MFN2 axis.

miR-761-hepcidin/Gpx4 pathway contribute to unexplained liver dysfunction in polycystic ovary syndrome by regulating liver iron overload and ferroptosis.

Aims: To investigate the underling mechanisms of liver dysfunction in patients with polycystic ovary syndrome (PCOS).Materials and methods: PCOS patients were enrolled according to the Amsterdam criteria while PCOS animal model was established by dihydrotestosterone (DHEA) sustained release tablet implantation on its neck. Further liver damage and iron overload were detected by HE and Prussian blue staining. The liver related enzymes, mRNA and protein levels of hepcidin and GPX4 were tested by ELISA, qRT-PCR and Western blot. RNA interference and miR-761 transfection were routinely performed while the regulation of miR-761 on hepcidin and GPX4 was confirmed by luciferase reporter gene analysis.Results: We found that a part of PCOS patients and animal model had unexplained liver damage, which is independent of nonalcoholic fatty liver disease (NAFLD) and accompanied by increased ferrum (Fe) deposition. Besides, the expression of hepcidin and GPX4 that is important effector proteins for ferroptosis was down regulated in liver, showing the importance of iron metabolism in this unexplained liver damage. Based on the miR-761-hepcidin/GPX4 axis, we systematically studied the effects of miR-761 on ferroptosis and Fe deposition, which further influence the phenotype and liver function of PCOS model. From both in vivo and in vitro levels, changes in PCOS disease phenotype and ferroptosis were observed through hierarchical antagonism or overexpression of miR-761, hepcidin and GPX4.Conclusions: our results provide a novel explanation for unexplained liver damage in PCOS and a potential therapeutic target.

CircDUSP1 regulates tumor growth, metastasis, and paclitaxel sensitivity in triple-negative breast cancer by targeting miR-761/DACT2 signaling axis.

Triple-negative breast cancer TNBC) is a malignant tumor with high incidence and high mortality that threaten the health of women worldwide. Circular RNAs (circRNAs) are a new class of noncoding RNAs that participate in the biological processes of various tumors, but the regulatory roles of circRNAs in TNBC have not been fully elucidated. In this study, the expression and characterization of circDUSP1 was detected via quantitative real-time PCR, nuclear-cytoplasmic fractionation assay, and fluorescence in situ hybridization. Then, in vitro and in vivo functional experiments were performed to evaluate the effects of circDUSP1 in TNBC. The interaction among circDUSP1, miR-761, DACT2 were confirmed by dual luciferase reporter assay, RNA pull-down, and RNA immunoprecipitation experiments. We identified the circRNA named circDUSP1 that was inversely correlated with tumorigenesis and progression in TNBC. Overexpression of circDUSP1 significantly attenuated cell proliferation, migration, invasion, and epithelial-mesenchymal transition, while increased the sensitivity of TNBC cells to paclitaxel. In-depth mechanism analysis indicated that circDUSP1 acts as an endogenous sponge of miR-761 to reduce its suppression on target gene DACT2 expression in TNBC. Upregulation of miR-761 or downregulation of DACT2 partially reversed the biological process of TNBC and the prognosis of paclitaxel affected by circDUSP1. Taken together, our findings revealed a role for the regulation of the miR-761/DACT2 axis by circDUSP1 in the biological process of TNBC. These results provided new insights into the biological mechanism and targeted therapy of TNBC.

Circ_0061140 Contributes to Ovarian Cancer Progression by Targeting miR-761/LETM1 Signaling.

Previous studies have suggested that circular RNAs (circRNAs) play important regulatory roles in cancer progression. Previous evidence exhibited the aberrant upregulation of circ_0061140 in ovarian cancer. However, the detailed role of circ_0061140 in ovarian cancer progression and its associated mechanism remain largely unknown and need further exploration. The expression of circ_0061140, microRNA-761 (miR-761) and leucine zipper and EF-hand containing transmembrane protein 1 (LETM1) was checked by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) or western blot. Cell Counting Kit-8 (CCK8), colony formation, 5-Ethynyl-2'-deoxyuridine (EdU), flow cytometry, wound healing, transwell, and tube formation assays were conducted to assess cell functions. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were performed to confirm the interaction between miR-761 and circ_0061140 or LETM1. Xenograft tumor model was established to analyze the role of circ_0061140 in tumor growth in vivo. Circ_0061140 expression was notably up-regulated in ovarian cancer tissues and cell lines. Circ_0061140 knockdown suppressed the proliferation, migration, invasion, and angiogenesis and triggered the apoptosis of ovarian cancer cells. Circ_0061140 directly interacted with miR-761, and circ_0061140 silencing-mediated anti-tumor effects were partly abolished by miR-761 knockdown in ovarian cancer cells. LETM1 was a direct target of miR-761, and LETM1 overexpression partly counteracted miR-761-induced anti-tumor effects. Circ_0061140 could up-regulate LETM1 expression by sponging miR-761. Circ_0061140 knockdown significantly suppressed xenograft tumor growth in vivo. Circ_0061140 aggravated ovarian cancer progression through miR-761-dependent regulation of LETM1.

circRNA-MSR regulates the expression of FBXO21 to inhibit chondrocyte autophagy by targeting miR-761 in osteoarthritis.

Osteoarthritis (OA) is a chronic degenerative joint disease and is the most prevalent and disabling form of arthritis worldwide. Autophagy plays a vital role in OA. This study aimed to explore whether covalently closed circular RNA MSR (circRNA-MSR) could affect the F-box Only Protein 21 (FBXO21) expression by targeting microRNA-761 (miR-761), thereby affecting the autophagy in OA chondrocytes. Clinical OA tissues were collected, and circRNA-MSR, miR-761, and FBXO21 expressions were detected via quantitative real-time polymerase chain reaction (qRT-PCR). An in vitro OA model was constructed by treating C28/I2 cells with LPS and treating them with overexpression or knockdown vector of circRNA-MSR, miR-761, and FBXO21, and autophagy inhibitor 3-MA. Fluorescence in situ hybridization (FISH) determined the location of circRNA-MSR and miR-761. Dual-luciferase assay assessed circRNA-MSR and miR-761, along with the bindings of miR-761 and FBXO21. Cell viability was detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. LC3 II/I, p62 and beclin 1 expressions were detected via the western blot. circRNA-MSR and FBXO21 levels were elevated in OA, but miR-761 level was inhibited. Suppressing circRNA-MSR promoted the autophagy of LPS-treated cells. circRNA-MSR could bind to miR-761 and inhibit its expression. MiR-761 inhibition reversed the promoted autophagy caused by circRNA-MSR knockdown in LPS-treated C28/I2 cells. Moreover, miR-761 could target FBXO21 and inhibit its expression. FBXO21 overexpression reversed the increased autophagy caused by miR-761 overexpression in LPS-treated C28/I2 cells. circRNA-MSR could affect FBXO21 level via targeting miR-761, thereby repressing autophagy in OA chondrocytes, providing a new target and strategy for OA treatment.

The abnormal expression of circ-ARAP2 promotes ESCC progression through regulating miR-761/FOXM1 axis-mediated stemness and the endothelial-mesenchymal transition.

Circular RNAs (circRNAs) belong to a novel class of noncoding RNA that gained more attention in human cancer pathogenesis. The role of circRNA in esophageal squamous cell carcinoma (ESCC) is largely unclear. Present investigation was to characterize new circRNAs regulating ESCC progression and explore the regulatory mechanisms in ESCC. In this study, circRNAs differentially expressed in ESCC and adjacent normal tissues were characterized via high-throughput sequencing. Then the differentially expressed circRNA between ESCC and adjacent normal tissues were investigated using Rt-qPCR. The role of circ-ARAP2 expression on tumor progression were detected in both in vivo and in vitro. Luciferase reporter assays were used to identify the relationships among circ-ARAP2, microRNA (miR)-761 and the cell cycle regulator Forkhead Box M1 (FOXM1). The result of the expression profile analyses regarding human circRNAs in ESCC demonstrated that circ-ARAP2 was up-regulated significantly in both ESCC tissues and cell lines. Downregulation circ-ARAP2 suppressed ESCC proliferation, tumor growth and metastasis in both in vivo and in vitro. The data also suggested that miR-761 and FOXM1 were circ-ARAP2 downstream targets which were confirmed through luciferase reporter analysis. Overexpression of FOXM1 or inhibiting miR-761 restored ESCC cell proliferation and invasion ability after silencing circ-ARAP2. The study also found that circ-ARAP2 influenced the endothelial-mesenchymal transition (EMT) and cancer stem cells differently by regulating miR-761/FOXM1. In one word, the results demonstrated that abnormal circ-ARAP2 expression promoted ESCC progression by regulating miR-761/FOXM1 axis-mediated stemness and EMT.

Suppression of MIR31HG affects the functional properties of thyroid cancer cells depending on the miR-761/MAPK1 axis.

BACKGROUND: Thyroid cancer is the most prevalent endocrine malignancy. Long non-coding RNA (lncRNA) MIR31HG is abnormally expressed in thyroid cancer tissues. However, the precise, critical role of MIR31HG in thyroid cancer development remains unclear. METHODS: MIR31HG, microRNA (miR)-761 and mitogen-activated protein kinase 1 (MAPK1) were quantified by quantitative real-time PCR (qRT-PCR) and immunoblotting. Cell viability, proliferation, apoptosis, invasion and migration abilities were evaluated by MTS, 5-Ethynyl-2'-Deoxyuridine (EdU), flow cytometry, transwell and wound-healing assays, respectively. Dual-luciferase reporter assays were used to validate the direct relationship between miR-761 and MIR31HG or MAPK1. RESULTS: MIR31HG was overexpressed in human thyroid cancer, and its overexpression predicted poor prognosis. Suppression of MIR31HG impeded cell proliferation, invasion and migration, as well as promoted cell apoptosis in vitro, and diminished the growth of xenograft tumors in vivo. Mechanistically, MIR31HG targeted and regulated miR-761. Moreover, miR-761 was identified as a molecular mediator of MIR30HG function in regulating thyroid cancer cell behaviors. MAPK1 was established as a direct and functional target of miR-761 and MAPK1 knockdown phenocopied miR-761 overexpression in impacting thyroid cancer cell behaviors. Furthermore, MIR31HG modulated MAPK1 expression by competitively binding to miR-761 via the shared binding sequence. CONCLUSION: Our findings demonstrate that MIR31HG targets miR-761 to regulate the functional behaviors of thyroid cancer cells by upregulating MAPK1, highlighting a strong rationale for developing MIR31HG as a novel therapeutic target against thyroid cancer.

Long Non-coding RNA LOXL1-AS1 Facilitates Colorectal Cancer Progression via Regulating miR-1224-5p/miR-761/HK2 Axis.

Colorectal cancer (CRC) is one of the most common cancers worldwide. Long non-coding RNAs (lncRNAs) play crucial roles in the development of malignant tumors. The present study aimed to explore the function and potential mechanism of lncRNA LOXL1 antisense RNA 1 (LOXL1-AS1) in CRC. The abundance of LOXL1-AS1, miR-1224-5p, miR-761, and hexokinase 2 (HK2) was detected by quantitative real-time PCR or western blot assay. Cell proliferation was assessed by Cell Counting Kit-8 and colony formation assays. Cell apoptosis, invasion, and migration were examined by flow cytometry, transwell assay, and wound healing assay. Glycolysis was evaluated by detecting glucose consumption, lactate production, and ATP/ADP ratios. Xenograft assay was used for in vivo tumor growth analysis. LOXL1-AS1 and HK2 levels were increased, while miR-1224-5p and miR-761 levels were reduced in CRC tissues and cells. Knockdown of LOXL1-AS1 suppressed CRC cell proliferation, invasion, migration, and glycolysis, and induced cell apoptosis. Silencing of LOXL1-AS1 blocked tumor growth in vivo. Moreover, LOXL1-AS1 accelerated CRC cell progression by absorbing miR-1224-5p/miR-761. Besides, miR-1224-5p and miR-761 inhibited CRC cell progression via targeting HK2. LOXL1-AS1 contributed to CRC progression via modulating miR-1224-5p/miR-761/HK2 pathway.

Exosomal lncRNA HOTAIR Promotes the Progression and Angiogenesis of Endometriosis via the miR-761/HDAC1 Axis and Activation of STAT3-Mediated Inflammation.

Background: Long non-coding RNA (lncRNA) and exosomes are implicated in endometriosis development. We measured the expression of an exosomal lncRNA, homeobox transcript antisense RNA (HOTAIR), and explored its molecular mechanism in endometriosis progression. Methods: Expression of HOTAIR and microRNA (miR)-761 in different endometrial tissues was measured. Exosomes were isolated from a culture medium of endometrial stromal cells (ESCs). RT-qPCR was used to measure HOTAIR expression in different exosome types. CCK-8, Edu, wound healing, transwell assays, flow cytometry and tube formation were used to detect the role of exosomal HOTAIR on ESCs and human umbilical vein endothelial cells (HUVECs). The relationship among miR-761, HOTAIR, and histone deacetylase 1 (HDAC1) was verified by dual-luciferase reporter assay. ESCs were transfected with miR-761 mimics or HDAC1 small interfering RNA (si-RNA) to ascertain if alterations in expression of miR-761 or HDAC1 could reverse the effect of exosomal HOTAIR. Then, we detected the effect of the HOTAIR/miR-761/HDAC1 axis on signal transducer and activator of transcription 3 (STAT3)-mediated inflammation. In vivo experiments were conducted to verify in vitro results. Results: HOTAIR expression was upregulated and miR-761 expression was downregulated in ectopic endometrium tissues. HOTAIR was packaged into exosomes and transported from ESCs to surrounding cells. Exosomal HOTAIR promoted the proliferation, migration, and invasion, and inhibited the apoptosis of ESCs. Angiogenesis of HUVECs was enhanced after cultured with exosomal HOTAIR. HOTAIR acted as a competing endogenous RNA to downregulate miR-761 and increase HDAC1 expression. miR-761 overexpression or HDAC1 knockdown reversed the role of exosomal HOTAIR on ESCs and HUVECs. The HOTAIR/miR-761/HDAC1 axis could activate STAT3-related proinflammatory cytokines and stattic (inhibitor of phosphorylated-STAT3) could reverse the effect of HOTAIR on ESCs and HUVECs. In vivo experiments suggested that exosomal HOTAIR promoted the growth of endometrial lesions in vivo. Conclusion: Exosomal HOTAIR promoted the progression and angiogenesis of endometriosis by regulating the miR-761/HDAC1 axis and activating STAT3-mediated inflammation in vitro and in vivo, which may provide promising treatment for endometriosis.

Long Noncoding RNA KCNQ1OT1 Confers Gliomas Resistance to Temozolomide and Enhances Cell Growth by Retrieving PIM1 From miR-761.

Many studies have found that the dysregulation of long noncoding RNA (lncRNA) contributed to cancer initiation, progression, and recurrence via multiple signaling pathways. However, the underlying mechanisms of lncRNA in temozolomide (TMZ)-resistant gliomas were not well understood, hindering the improvement of TMZ-based therapies. The present study demonstrated that the lncRNA KCNQ1OT1 increased in TMZ-resistant glioma cells compared to the TMZ-sensitive cells. The introduction of KCNQ1OT1 promoted cell viability, clonogenicity, and rhodamine 123 efflux while hampering TMZ-induced apoptosis. Moreover, KCNQ1OT1 directly sponged miR-761, which decreased in TMZ-resistant sublines. The overexpression of miR-761 attenuated cell viability and clonogenicity, while triggering apoptosis and rhodamine 123 accumulation post-TMZ exposure, leading to a response to TMZ. The interaction between miR-761 and 3'-untranslated region of PIM1 attenuated PIM1-mediated signaling cascades. Furthermore, the knockdown of KCNQ1OT1 augmented the TMZ-induced tumor regression in TMZ-resistant U251 mouse models. Briefly, the present study evaluated that KCNQ1OT1 conferred TMZ resistance by releasing PIM1 expression from miR-761, resulting in the upregulation of PIM-mediated MDR1, c-Myc, and Survivin. The present findings demonstrated that the interplay of KCNQ1OT1: miR-761: PIM1 regulated chemoresistance in gliomas and provided a promising therapeutic target for TMZ-resistant glioma patients.

CircIL4R activates the PI3K/AKT signaling pathway via the miR-761/TRIM29/PHLPP1 axis and promotes proliferation and metastasis in colorectal cancer.

BACKGROUND: Accumulating studies have revealed that aberrant expression of circular RNAs (circRNAs) is widely involved in the tumorigenesis and progression of malignant cancers, including colorectal cancer (CRC). Nevertheless, the clinical significance, levels, features, biological function, and molecular mechanisms of novel circRNAs in CRC remain largely unexplored. METHODS: CRC-related circRNAs were identified through bioinformatics analysis and verified in clinical specimens by qRT-PCR and in situ hybridization (ISH). Then, in vitro and in vivo experiments were performed to determine the clinical significance of, functional roles of, and clinical characteristics associated with circIL4R in CRC specimens and cells. Mechanistically, RNA pull-down, fluorescence in situ hybridization (FISH), luciferase reporter, and ubiquitination assays were performed to confirm the underlying mechanism of circIL4R. RESULTS: CircIL4R was upregulated in CRC cell lines and in sera and tissues from CRC patients and was positively correlated with advanced clinicopathological features and poor prognosis. Functional experiments demonstrated that circIL4R promotes CRC cell proliferation, migration, and invasion via the PI3K/AKT signaling pathway. Mechanistically, circIL4R was regulated by TFAP2C and competitively interacted with miR-761 to enhance the expression of TRIM29, thereby targeting PHLPP1 for ubiquitin-mediated degradation to activate the PI3K/AKT signaling pathway and consequently facilitate CRC progression. CONCLUSIONS: Our findings demonstrate that upregulation of circIL4R plays an oncogenic role in CRC progression and may serve as a promising diagnostic and prognostic biomarker for CRC detection and as a potential therapeutic target for CRC treatment.

LncRNA TPTEP1 inhibited the proliferation and metastasis of non-small cell lung cancer cells by targeting miR-761/LATS2 axis.

OBJECTIVE: Non-small cell lung cancer (NSCLC) is highly metastatic that can lead to high fatality rate. This study aimed at investigating the possible role of LncRNA TPTEP1 (TPTEP1) in NSCLC progression. METHODS: Cell proliferation was determined by MTT and colony formation assays. Transwell and scratch assays were adopted to assess cellular metastasis. RT-qPCR and western blot were used to detect TPTEP1 expression transcriptionally and translationally, respectively. The dual luciferase reporter assay and RNA immunoprecipitation assay were used to identify the specific target relationships. RESULTS: Compared with the normal adjacent tissues, the expressions of TPTEP1 and LATS2 were significantly down-regulated in the NSCLC tissues, while the expression of miR-761 was significantly increased. Overexpression of TPTEP1 exhibited substantial antitumor effects on NSCLC, including inhibition of cell proliferation and metastasis, which was achieved by targeting miR-761 and subsequently attenuated the expression of LATS2. LATS2 was identified as a direct target of miR-761. Overexpression of miR-761 could significantly block the inhibitory effects of TPTEP1 on NSCLC, which clearly indicated that miR-761 played an oncogenic role in promoting proliferation and metastasis, while its downstream factor, LATS2, exerted opposite effects. CONCLUSION: The study showed that TPTEP1 played an inhibitory role in cancer progression of NSCLC cells by regulating miR-761/LATS2 cascade, thereby highlighting the potential therapeutic significance of TPTEP1/miR-761/LATS2 axis.

Long non-coding RNA HOTAIR/microRNA-761 sponge regulates PPME1 and further influences cell biological functions in thyroid carcinoma.

BACKGROUND: Most well-differentiated thyroid carcinomas display good therapeutic outcomes, but there are still some patients who are not sensitive to the general treatments lose their treatment opportunities. Thus, it is important to understand the molecular mechanisms that cause thyroid carcinoma, so as to find effective diagnostic and therapeutic targets. AIM OF THE STUDY: To explore the role of homeobox transcript antisense RNA (HOTAIR) in thyroid carcinoma through protein phosphatase methylesterase 1 (PPME1) by sponging microRNA 761 (miR-761). METHODS: The regulation network amongst HOTAIR, miR-761 and PPME1 was predicted by online sources. RT-PCR was conducted to evaluate the expression of HOTAIR and miR-761 in tumor tissues. Clinical data was collected and analyzed by Chi-square test. Cell apoptosis and proliferation was evaluated using three types of cancer cells (HTh-7, CAL-62, BCPAP) after treated with si-HOTAIR and miR-761inhibitor. The binding site among HOTAIR, miR-761 and PPME1 was verified by dual luciferase reporter assay. PPME1 expression was measured after HOTAIR and miR-761 were suppressed by western blot. Survival time was measured in nude mice using log-rank test. RESULTS: HOTAIR was expressed to a significantly greater extent than miR-761 in thyroid tumor tissues (P < .001). miR-761 and PPME1 were negatively correlated (coef = -1.91, P < .001). HOTAIR competitively binds to miR-761 and miR-761 directly targets PPME1. HOTAIR was highly correlated with TNM (χ 2 = 5.797, P = .016), tumor size (χ 2 = 7.955, P = .005) and lymphatic metastasis (χ 2 = 6.0, P = .014). HOTAIR promoted cell proliferation and inhibited cell apoptosis, whereas miR-761 did not. HOTAIR elevated and miR-761 suppressed PPME1 expression. HOTAIR expression appears to affect the survival time in vivo. CONCLUSION: HOTAIR regulated thyroid cancer cells by binding to miR-761 through PPME1.

Use Chou's 5-steps rule to study how Baicalin suppresses the malignant phenotypes and induces the apoptosis of colorectal cancer cells.

Baicalin is a traditional Chinese herb purified from the root of Scutellaria baicalensis Georgi. In this study, we further analyzed the molecular mechanism behind the anti-tumor activity of Baicalin in colorectal cancer (CRC). The establishment of circular RNA (circRNA)/microRNA (miRNA)/messenger RNA (mRNA) axis was predicted by bioinformatic databases and verified by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. Baicalin dose-dependently reduced the expression of circRNA myosin heavy chain 9 (circMYH9) in CRC cells. Baicalin exposure suppressed the malignant phenotypes of CRC cells, which were largely reversed by the overexpression of circMYH9. CircMYH9 functioned as a molecular sponge for miR-761. CircMYH9 overexpression protected CRC cells from Baicalin-induced injury partly through down-regulating miR-761. MiR-761 interacted with the 3' untranslated region (3' UTR) of hepatoma-derived growth factor (HDGF) mRNA. CircMYH9 up-regulated HDGF expression partly through sponging miR-761 in CRC cells. MiR-761 silencing counteracted the anti-tumor activity of Baicalin partly through up-regulating HDGF in CRC cells. Baicalin suppresses xenograft tumor growth in vivo, and this suppressive effect was partly reversed by the overexpression of circMYH9. In conclusion, Baicalin exhibited an anti-tumor activity in CRC cells partly through down-regulating circMYH9 and HDGF and up-regulating miR-761.

LncRNA LINC01535 promotes colorectal cancer development and chemoresistance by sponging miR-761.

Colorectal cancer (CRC) is one of the most common human cancer types and a leading cause of cancer-related death. Accumulating evidence has confirmed that long non-coding RNAs have crucial roles in CRC progression. In the present study, the biological roles of LINC01535 were investigated and the interaction between long intergenic non-coding RNA (LINC)01535 and microRNA (miR)-761 in CRC was explored. LINC01535 expression was observed to be upregulated in CRC tissues and cell lines. A functional study suggested that LINC01535 silencing inhibited CRC cell proliferation and invasion but enhanced cisplatin sensitivity of CRC cells, while co-transfection with a miR-761 inhibitor reversed these biological effects. A luciferase reporter assay demonstrated that LINC01535 regulated miR-761 directly and RNA-binding protein immunoprecipitation further confirmed that the suppression of LINC01535 by miR-761 was via an RNA-induced silencing complex. Finally, knockdown of LINC01535 inhibited the growth of CRC cells in vivo. Collectively, the results suggested that LINC01535 exerts oncogenic functions in CRC by sponging miR-761. In conclusion, the present study indicated that LINC01535 promoted CRC progression through sponging miR-761, and may serve as a potential diagnostic biomarker and therapeutic target for CRC.

Imbalance of Molecular Module of TINCR-miR-761 Promotes the Metastatic Potential of Early Triple Negative Breast Cancer and Partially Offsets the Anti-Tumor Activity of Luteolin.

BACKGROUND: Triple negative breast cancer (TNBC) poses a great threat to patient prognosis. LncRNA-miRNA is a molecular module formed by a long non-coding RNA (LncRNA) and a microRNA (miRNA) that mediates the metastatic potential of tumours such as TNBC, and luteolin (LU) is a natural compound with anti-TNBC activity. OBJECTIVE: We aim to explore the regulatory mechanism of terminal differentiation-induced non-coding RNA (TINCR)-miR-761 molecular module in early TNBC, as well as its influence on anti-tumor activity of LU. METHODS: The serum was collected from TNBC patients in early stage to detect the expression of TINCR and miR-761 using RT-PCR. Transwell method was applied for the determination of cell migration and invasion, Western blot for epithelial-mesenchymal transition (EMT), flow cytometry (FCM) for cell apoptosis, and dual luciferase reporter and RNA pull-down experiment for the verification of the targeted relationship between TINCR and miR-761. RESULTS: Both TINCR and miR-761 were up-regulated in the serum of patients with early TNBC and the area under the curve (AUC) of the two for distinguishing TNBC from BC was not less than 0.850. In the cell function tests, down-regulation of TINCR or miR-761 notably suppressed the metastatic potentials (cell migration, invasion and EMT) of TNBC cells were remarkably inhibited, while up-regulation of TINCR or miR-761 notably promoted the metastatic potentials. We also confirmed that TINCR acts as the molecular sponge of miR-761, and has positive regulation on it. Besides, LU can significantly down-regulate TINCR and miR-761, and partially offset the anti-TNBC activity of LU when they were abnormally up-regulated, which was mainly reflected in the decrease of anti-proliferation and pro-apoptotic ability of LU against TNBC. CONCLUSION: There is an imbalance of TINCR-miR-761 molecular module in early TNBC, which may be a potential new therapeutic target of TNBC.

Circular RNA profiling identifies circ102049 as a key regulator of colorectal liver metastasis.

Circular RNA (circRNA) plays an essential role in the development and progression of various cancers. However, the functions and mechanisms of circRNA in colorectal liver metastasis have not been fully elucidated. We performed circRNA microarray analysis to screen differentially expressed circRNA in the pathology of colorectal liver metastasis. Quantitative real-time PCR was used to detect the expression of hsa_circ_102049 (circ102049) in colorectal cancer (CRC) samples. CRC cells were transfected with circ102049 overexpression vector or small interfering (si)RNA to assess the effects of circ102049 in vitro. Bioinformatics analysis, fluorescence in situ hybridization, RNA immunoprecipitation, RNA pull-down and luciferase reporter assays were conducted to confirm the relationship of circ102049, miR-761, miR-192-3p and FRAS1. The mechanism by which circ102049 recruits and distributes DGCR8 protein in the cytoplasm was also investigated. We found that circ102049 was highly expressed in primary CRC tumors with liver metastasis and closely correlated with the prognosis of patients with CRC. Circ102049 significantly enhanced the adhesion, migration and invasion abilities of CRC cells, and promoted CRC progression via a micro (mi)R-761/miR-192-3p-FRAS1-dependent mechanism. Notably, due to the distribution of DGCR8 protein, circ102049 may also indirectly reduce the levels of mature miR-761 and miR-192-3p in the cytoplasm. In addition, the role of circ102049 in promoting colorectal liver metastasis was confirmed in vivo. Our findings provide new evidence that circ102049 may be a potential prognostic factor in CRC, and that the circ102049-miR-761/miR-192-3p-FRAS1 axis may be an anti-metastatic target for CRC patients.

MicroRNA-761 suppresses tumor progression in osteosarcoma via negatively regulating ALDH1B1.

AIMS: Our previous study has demonstrated that high expression of ALDH1B1 promoted osteosarcoma tumor progression and was correlated with unfavorable prognosis in osteosarcoma patients. In the current study, we investigated the underlying mechanism and regulation of ALDH1B1 in osteosarcoma. MATERIALS AND METHODS: qRT-PCR assay was applied to detect miR-761 expression. CCK-8, colony formation and EdU assays were conducted to explore the functional role of miR-761/ALDH1B1 axis in osteosarcoma. Bioinformatics analysis and luciferase reporter assay was utilized to assess the regulation between miR-761 and ALDH1B1. Mechanism experiments were implemented to investigate the underlying molecular mechanism of miR-761/ALDH1B1 axis. KEY FINDINGS: ALDH1B1 was negatively regulated by microRNA-761 (miR-761). Functionally, miR-761 suppressed cell growth, migration, and invasion in osteosarcoma via targeting ALDH1B1 in vitro. Xenograft tumor model demonstrated that miR-761 inhibited osteosarcoma tumor development in vivo through regulating ALDH1B1. Consistently, we showed that miR-761 expression was decreased in osteosarcoma patients and low expression of miR-761 was correlated with worse prognosis in osteosarcoma patients. Mechanistically, we revealed that high expression of ALDH1B1 was significantly associated with enhanced TGF-ß signaling, epithelial-mesenchymal transition (EMT), and cell adhesion. Furthermore, miR-761 regulated TGF-ß and EMT/cell adhesion in osteosarcoma via targeting ALDH1B1. SIGNIFICANCE: Taken together, our findings suggest that the oncogenic ALDH1B1 is regulated by miR-761 during osteosarcoma development and progression, which might provide a novel prognostic biomarker and therapeutic strategy for osteosarcoma treatment.

MicroRNA-761 modulates foam cell formation and inflammation through autophagy in the progression of atherosclerosis.

Macrophage-derived foam cells formation is the initial stage of atherosclerosis, and lipid-laden macrophage accumulation is also considered as the symbol of unstable plaque. Autophagy is a subcellular process responsible for the degradation of damaged organelles and aggregated proteins in cells (Grootaert in Oxid Med Cell Longev: 7687083, 2018). Macrophage autophagy plays an important role in atherosclerosis under various stress conditions, and microRNAs are involved in this complicated process. The present study was programmed to explore the effects of microRNA-761 on macrophage-derived foam cell formation, focusing on the role of autophagy in this pathological process. The differentiated human THP-1 macrophages were used in the study. THP-1-derived macrophages were treated with miR-761 mimics or inhibitors and cultured with oxidized low-density lipoprotein to mimic the lipid-rich environment in blood vessel. The expression of miR-761 and mRNA levels of IL-1ß and IL-18 were analyzed by quantitative real-time PCR. The effect of miR-761 on autophagy was evaluated by the protein levels of Beclin1, p62/SQSTM1, microtubule-associated protein light chain 3, mammalian target of rapamycin (mTOR), and unc-51-like autophagy activating kinase 1 (ULK1), determined by immunoblot and autophagic flux detected by fluorescent staining. The secretion of IL-1ß and IL-18 was tested by enzyme-linked immunosorbent reaction kit. Lipid accumulation in foam cells was detected by oil red "O" staining. We demonstrated that miR-761 was able to repress foam cell formation and reduce the production of atherogenic inflammatory cytokines IL-1ß and IL-18 in an autophagy-dependent manner in atherosclerosis, possibly via mTOR-ULK1 signaling pathway. In summary, we described an athero-protective function of miR-761 in macrophages incubated with excess ox-LDL and identified an important novel modulator of mTOR signaling and autophagy in macrophage-derived foam cells. This finding may provide a potential target for the prevention and early treatment in high-risk group of atherosclerosis.

The long noncoding RNA Arrl1 inhibits neurite outgrowth by functioning as a competing endogenous RNA during neuronal regeneration in rats.

The intrinsic regeneration ability of neurons is a pivotal factor in the repair of peripheral nerve injury. Therefore, identifying the key modulators of nerve regeneration may help improve axon regeneration and functional recovery after injury. Unlike for classical transcription factors and regeneration-associated genes, the function of long noncoding RNAs (lncRNAs) in the regulation of neuronal regeneration remains mostly unknown. In this study, we used RNA-Seq-based transcriptome profiling to analyze the expression patterns of lncRNAs and mRNAs in rat dorsal root ganglion (DRG) following sciatic nerve injury. Analyses using the lncRNA-mRNA co-expression network, gene ontology enrichment, and Kyoto Encyclopedia of Genes and Genomes pathway databases indicated that the lncRNA Arrl1 decreases neurite outgrowth after neuronal injury. shRNA-mediated Arrl1 silencing increased axon regeneration both in vitro and in vivo and improved functional recovery of the sciatic nerve. Moreover, inhibiting an identified target gene of Arrl1, cyclin-dependent kinase inhibitor 2B (Cdkn2b), markedly promoted neurite outgrowth of DRG neurons. We also found that Arrl1 acts as a competing endogenous RNA that sponges a Cdkn2b repressor, microRNA-761 (miR-761), and thereby up-regulates Cdkn2b expression during neuron regeneration. We conclude that the lncRNA Arrl1 affects the intrinsic regeneration of DRG neurons by derepressing Cdkn2b expression. Our findings indicate a role for an lncRNA-microRNA-kinase pathway in the regulation of axon regeneration and functional recovery following peripheral nerve injury in rats.