MiR-526b targets lncRNA SLC16A1-AS1 to suppress cell proliferation in triple-negative breast cancer.

The present study investigated the potential interaction between miR-526b and lncRNA SLC16A1-AS1 in triple-negative breast cancer (TNBC). Expression of miR-526b and SLC16A1-AS1 in TNBC tumor tissues and paired nontumor tissues from 60 TNBC patients was detected by real-time polymerase chain reaction (RT-qPCR). The interaction between miR-526b and SLC16A1-AS1 was evaluated with overexpression experiments, followed by RT-qPCR. The proliferation and migration of cells were detected with cell counting kit-8 assay and Transwell assay, respectively. Apoptosis of cells was assessed by cell apoptosis assay. The expression of apoptosis-related proteins was quantified by Western blot analysis. MiR-526b was predicted to bind with SLC16A1-AS1. Overexpression of miR-526b in TNBC cells decreased the expression levels of SLC16A1-AS1, while overexpression of SLC16A1-AS1 did not affect the expression of miR-526b. In TNBC tissues, miR-526b was downregulated in TNBC tissues, while SLC16A1-AS1 was upregulated in TNBC tissues compared to that in nontumor tissues. The expression of SLC16A1-AS1 and miR-526b were inversely correlated. In vitro experiments showed that overexpression of SLC16A1-AS1 promoted cell proliferation and invasion but suppressed cell apoptosis. MiR-526b played an opposite role and suppressed the function of SLC16A1-AS1. MiR-526b is downregulated in TNBC and it targets SLC16A1-AS1 to regulate proliferation, apoptosis, and invasion of TNBC cells.

Silencing CircEIF3I/miR-526b-5p Axis Epigenetically Targets HGF/c-Met Signal to Hinder the Malignant Growth, Metastasis and Angiogenesis of Hepatocellular Carcinoma.

BACKGROUND: Hepatocyte growth factor (HGF)/c-mesenchymal-epithelial transition factor (c-Met) is important for the diagnosis and prognosis of hepatocellular carcinoma (HCC). Circular RNAs (circRNAs) are key regulators of HCC progression, and this study focused on circRNA eukaryotic translation initiation factor 3 subunit I (circEIF3I) with HGF/c-Met in HCC. METHODS: Levels of circEIF3I, microRNA (miR)-526b-5p, HGF, E-cadherin, N-cadherin, and Vimentin were detected by Gene Expression Omnibus database, quantitative PCR and western blotting. Cell functions were measured by detecting cell growth (cell proliferation assay with WST-1 and EdU, colony formation assay, flow cytometry, caspase 3 activity assay, and nude mouse tumorigenicity assay), metastasis (transwell assay and western blotting), angiogenesis (endothelial tube formation assay). Molecular interaction was determined dual-luciferase reporter assay, RNA immunoprecipitation, and Pearson correlation analysis. RESULTS: Expression of circEIF3I was upregulated in HCC tissues. Knockdown of circEIF3I suppressed cell proliferation epithelial-mesenchymal transition, migration, invasion and tube formation ability but promoted apoptosis of HCC cells. CircEIF3I could sponge miR-526b-5pto regulate downstream HGF. Functionally, circEIF3I regulation in HCC cell progression was associated with miR-526b-5p sponging function and HGF upregulation could attenuate tumor-inhibiting roles of miR-526b-5p. HCC tumor growth was delayed by interfering circEIF3I. CONCLUSION: CircEIF3I was an oncogenic circRNA in HCC-, and interfering circEIF3I exhibited anti-HCC activity via circEIF3I-miR-526b-5p-HGF/c-Met pathway.

miR-526b-5p/c-Myc/Foxp1 participates in recurrent spontaneous abortion by regulating the proliferation, migration, and invasion of trophoblasts.

PURPOSE: As a member of the C19MC family, miR-526b-5p is mainly expressed in the placental tissue and is a well-known tumor suppressor microRNA. However, its effect on the function of trophoblasts and its role in the development of recurrent spontaneous abortion (RSA) remains unclear. METHODS: Transcriptome sequencing, quantitative real-time polymerase chain reaction (RT-qPCR), Western blot, 5-ethynyl-2'-deoxyuridine (Edu) proliferation analysis, cell counting kit-8 (CCK8) assay, Transwell assays, and wound healing were used to detect the proliferation, migration, and invasion capacity of trophoblasts. Target genes of miR-526b-5p were obtained by the dual luciferase reporter system. The promoter-reporter system and ChIP-qPCR were used to prove that c-Myc positively regulated the expression of Foxp1 RESULTS: The miR-526b-5p levels were significantly higher in patients with RSA than in controls. High expression of miR-526b-5p inhibited the proliferation, migration, and invasion of trophoblast cell line. By contrast, low expression of miR-526b-5p promoted the proliferation and migration of trophoblast cell line. Target genes of miR-526b-5p were c-Myc and Foxp1. c-Myc positively regulated the expression of Foxp1 by binding to the Foxp1 promoter location -146/-135. Finally, miR-526b-5p impeded the proliferation, migration, and invasion of trophoblasts by negatively regulating c-Myc by rescue experiments. CONCLUSION: Thus, miR-526b-5p affected the proliferation, migration, and invasion of trophoblasts by targeting c-Myc and Foxp1. Low expression of c-Myc further deactivated the positive transcriptional regulation of c-Myc on Foxp1, which may be the mechanism of RSA. This study provides potential therapeutic targets and clues for the diagnosis and treatment of RSA.

The LMCD1-AS1/miR-526b-3p/OSBPL5 axis promotes cell proliferation, migration and invasion in non-small cell lung cancer.

PURPOSE: To explore the specific role and regulatory mechanism of oxysterol binding protein like 5 (OSBPL5) in non-small cell lung cancer (NSCLC). METHODS AND RESULTS: Quantitative real-time polymerase chain reaction (qRT-PCR) analysis demonstrated that OSBPL5 expression was notably elevated in NSCLC tissues and cell lines, and Kaplan-Meier analysis manifested that high OSBPL5 expression was closely related to the poor prognosis of NSCLC patients. Besides, according to the results from western blot analysis, cell counting kit-8, EdU and Transwell assays, knockdown of OSBPL5 suppressed NSCLC cell proliferation, migration, invasion and epithelial-mesenchymal transition (EMT) process. Additionally, by performing qRT-PCR analysis, luciferase reporter and RNA pull-down assays, we verified that OSBPL5 was a downstream target of miR-526b-3p and long noncoding RNA (lncRNA) LMCD1-AS1 served as a sponge for miR-526b-3p. Moreover, from rescue assays, we observed that OSBPL5 overexpression offset LMCD1-AS1 knockdown-mediated inhibition in cell proliferation, migration, invasion and EMT in NSCLC. CONCLUSIONS: This paper was the first to probe the molecular regulatory mechanism of OSBPL5 involving the LMCD1-AS1/miR-526b-3p axis in NSCLC and our results revealed that the LMCD1-AS1/miR-526b-3p/OSBPL5 axis facilitates NSCLC cell proliferation, migration, invasion and EMT, which may offer a novel therapeutic direction for NSCLC.

LncRNA LOXL1-AS1 Facilitates the Oncogenic Character in Cervical Cancer by the miR-526b-5p /LYPLA1 Axis.

Increasing reports demonstrate that long noncoding RNAs participate in the regulation of numerous malignancies, cervical cancer included. Although lncRNA LOXL1 antisense RNA 1 has been commonly accepted to be an oncogene in many cancers. Here, the role of LOXL1-AS1 in CC still need to be explored. In this study, LOXL1-AS1 was found elevated in CC tissues and cells. LOXL1-AS1 depletion restrained CC cell proliferation, migration, invasion, and angiogenesis in vivo. Furthermore, we found that LOXL1-AS1 upregulated Lysophospholipase 1 expression via sequestering miR-526b-5p. Rescue assays revealed that overexpression of LYPLA1 reversed the LOXL1-AS1 silencing-induced inhibitory effects on the malignant phenotypes of CC cells. To conclude, this study showed that LOXL1-AS1 facilitates cellular process in CC via functioning as a miR-526b-5p sponge.

Circ_0002762 Accelerates Glycolysis Metabolism to Promote Cervical Cancer Progression via the miR-526b-5p/HK2 Axis.

OBJECTIVES: The purpose of this study was to investigate the role and mechanism of circ_0002762 in CC. DESIGN: This study was designed for silencing circ_0002762 in CC cells and xenograft tumor models to investigate the role of circ_0002762 in CC in vitro and in vivo. MATERIALS AND METHODS: The relative expression levels of circ_0002762, miR-526b-5p, and hexokinase2 (HK2) in CC tissues and cells were detected by real-time quantitative polymerase chain reaction or Western blot. Glycolysis-related extracellular acidification rate, glucose production, lactic acid consumption, and ATP levels were measured using the appropriate kits. Cell proliferation was assessed by 5-ethynyl-2'-deoxyuridine and colony formation assay. Cell apoptosis was detected by flow cytometry. The binding relationship between miR-526b-5p and circ_0002762 or HK2 was verified by dual-luciferase reporter assay and RNA pull-down assay. Tumor growth in vivo was detected by xenograft tumor model. RESULTS: The expressions of circ_0002762 and HK2 were up-regulated and miR-526b-5p was down-regulated in CC tissues and cells. Circ_0002762 knockdown inhibited glycolysis and proliferation and promoted apoptosis of CC cells. In addition, miR-526b-5p suppression reversed the inhibition of CC development induced by circ_0002762 silencing. HK2 overexpression eliminated the inhibition of miR-526b-5p on CC progression. Moreover, silencing of circ_0002762 inhibited CC tumor growth in vivo. LIMITATIONS: The practical application of circ_0002762 in clinical practice needs further investigation. CONCLUSION: Circ_0002762 knockdown inhibited CC progression by regulating miR-526b-5p/HK2 axis, suggesting that circ_0002762 was a promising therapeutic strategy for CC.

NCK1-AS1 promotes the progression of melanoma by accelerating cell proliferation and migration via targeting miR-526b-5p/ADAM15 axis.

BACKGROUND: Long non-coding RNAs (lncRNAs) are vital regulators of gene expression and cellular processes in multiple cancers, including melanoma. Nevertheless, the function of lncRNA NCK1-antisense 1 (NCK1-AS1) in melanoma remains unknown. METHODS: RT-qPCR was used to analyze the expression of NCK1-AS1, microRNA-526b-5p (miR-526b-5p) and ADAM metallopeptidase domain 15 (ADAM15). Cell proliferation was determined by CCK-8, colony formation and EdU assays. Cell migration was assessed by transwell migration and wound healing assays. Mechanism experiments including luciferase reporter, RIP and RNA pull down assays were conducted to demonstrate the interactions between RNAs. Xenograft model was established to verify the function of NCK1-AS1 and miR-526b-5p in melanoma in vivo. RESULTS: NCK1-AS1 was overexpressed in melanoma cell lines and NCK1-AS1 knockdown hampers the proliferation and migration of melanoma cells. Besides, miR-526b-5p binds to NCK1-AS1 in melanoma and ADAM15 was validated as its downstream target. Further, the inhibitory effects of NCK1-AS1 knockdown on cell proliferation and migration in melanoma were reversed by the depletion of miR-526b-5p and further counteracted by ADAM15 knockdown. The growth of melanoma tumors was hindered by the down-regulation of NCK1-AS1 or up-regulation of miR-526b-5p. CONCLUSION: NCK1-AS1 facilitates cell proliferation and migration in melanoma via targeting miR-526b-5p/ADAM15 axis.

Circ_0062166 aggravates cerebral ischemia-reperfusion injury through targeting miR-526b-5p/BCL2L13 axis.

BACKGROUND: Cerebral ischemia-reperfusion (CIR) injury is a severe disease, which may cause serious dysfunction of the brain. Most circular RNAs (circRNAs) have been demonstrated to play a significant role in CIR injury. However, a novel circRNA, circ_0062166 (circ_BCL2L13) has not been investigated for CIR injury. Hence, we aim to disclose the role of circ_0062166 in CIR injury in this study. METHODS: Firstly, RT-qPCR was applied to examine the expression of circ_0062166 in oxygen-glucose deprivation and reoxygenation (OGD/R) cell model. Functional assays were conducted to detect the role of circ_0062166 in CIR injury. RNA pull down, RIP and luciferase reporter assays were implemented to probe into the regulatory mechanism of circ_0062166. RESULTS: Circ_0062166 was significantly up-regulated in neuro-2A (N2A) neuroblastoma cells following OGD/R. Functionally, the silencing of circ_0062166 inhibited cell proliferation and promoted cell apoptosis under OGD/R condition. From the perspective of mechanism, circ_0062166 functioned as a competing endogenous RNA (ceRNA) for microRNA-526b-5p (miR-526b-5p) and regulated BCL2 like 13 (BCL2L13). Eventually, the promoting role of the circ_0062166/miR-526b-5p/BCL2L13 axis in the CIR injury was verified. CONCLUSION: To sum up, the present study has demonstrated that circ_0062166/miR-526b-5p/BCL2L13 axis accelerated the progression of CIR injury, which might provide effective strategies for CIR injury therapy.

Circular RNA PVT1 promotes metastasis via regulating of miR-526b/FOXC2 signals in OS cells.

As a class of covalently closed non-coding RNAs, circular RNAs (circRNAs) are key regulators in various malignancies including osteosarcoma (OS). In the present study, we found that circular RNA PVT1 (circPVT1) was up-regulated in OS and correlated with poor prognosis of patients with OS. Functionally, we showed that knockdown of circPVT1 suppressed OS cells metastasis. In addition, we found that (forkhead box C2) FOXC2 was a downstream gene in circPVT1-mediated metastasis in OS cells. We demonstrated that circPVT1 promoted OS cells metastasis via post-transcriptionally regulating of FOXC2. Furthermore, we revealed that microRNA 526b (miR-526b) was a key bridge which connected circPVT1 and FOXC2. We showed that miR-526b was down-regulated in OS tissue and cell lines. Through a transwell assay, we found that miR-526b suppressed OS cells metastasis by targeting of FOXC2. We also showed that miR-526b targeted circPVT1 via similar mircoRNA response elements (MREs) as it did for FOXC2. Finally, we proved that circPVT1 decoyed miR-526b to promote FOXC2-mediated metastasis in OS cells. In brief, our current study demonstrated that circPVT1, functioning as an oncogene, promotes OS cells metastasis via regulation of FOXC2 by acting as a ceRNA of miR-526b. CircPVT1/miR-526b/FOXC2 axis might be a novel target in molecular treatment of OS.

Long Noncoding RNA HOXD-AS1 Promotes the Proliferation, Migration, and Invasion of Colorectal Cancer via the miR-526b-3p/CCND1 Axis.

BACKGROUND: Colorectal cancer (CRC) is one of the most common malignancies in the world. It has been reported that the abnormal expression of long noncoding RNA HOXD-AS1 promotes the development of CRC, while the mechanism is still unclear. The aim of this study is to investigate the effects of HOXD-AS1 on proliferation, migration, and invasion in CRC and explore the underlying mechanism. METHODS: Quantitative real-time polymerase chain reaction was used to detect the expression levels of HOXD-AS1, miR-526b-3p, and cyclin D1 (CCND1) in CRC tissues and cells. Dual-luciferase reporter assay was applied to examine the interaction between miR-526b-3p and HOXD-AS1 or CCND1. In addition, cell proliferation ability was assessed by Cell Counting Kit-8 assay. Cell migration and invasion abilities were determined using transwell assay. Furthermore, Western blot assay was conducted to measure the protein expression of CCND1. RESULTS: HOXD-AS1 was highly expressed in CRC, and high expression of HOXD-AS1 was related to the poor prognosis of patients with CRC. MiR-526b-3p could be targeted by HOXD-AS1. Function experiment results revealed that miR-526b-3p inhibitor could reverse the suppressive effect of HOXD-AS1 knockdown on the proliferation, migration, and invasion of CRC cells. Moreover, CCND1 was a target of miR-526b-3p, and its overexpression could reverse the inhibitory effect of miR-526b-3p overexpression on the proliferation, migration, and invasion of CRC cells. In addition, CCND1 overexpression reversed the suppressive effect of HOXD-AS1 knockdown on the proliferation, migration, and invasion of CRC. CONCLUSIONS: HOXD-AS1 upregulated the expression of CCND1 to promote the proliferation, migration, and invasion of CRC through targeting miR-526b-3p. This provided a new theoretical basis for clinical anticancer research of CRC.

Circ_SPECC1 enhances the inhibition of miR-526b on downstream KDM4A/YAP1 pathway to regulate the growth and invasion of gastric cancer cells.

Gastric cancer (GC) is a common malignant tumor, and many studies have shown that circular RNAs (circRNAs) play important roles in the progress of GC. This study showed that circ_SPECC1 was down-regulated in various GC cell lines, significantly inhibited GC cell proliferation and invasion, and promote apoptosis, which might play an anti-oncogene role. Circ_SPECC1 was mainly located in the cytoplasm, and its sequence contained multiple potential binding sites of miR-526b. Pull-down experiments with biotinylated miR-526b mimics and circ_SPECC1 probe showed that they could enrich each other. RIP experiments found hat anti-AGO2 antibody could significantly enrich circ_SPECC1. Further dual luciferase reporter gene assay also confirmed that miR-526b could bind directly to circ_SPECC1. miR-526b was also down-regulated in GC cells, and one of its important target genes was KDM4A. Both circ_SPECC1 and miR-526b inhibited the expression of KDM4A and its downstream effector YAP1, but miR-526b inhibitors terminated the above-mentioned inhibition of circ_SPECC1, and KDM4A overexpression reversed the inhibition of circ_SPECC1 and miR-526b on YAP1 expression. Both miR-526b and KDM4A siRNA inhibited GC cell proliferation and invasion, and promote apoptosis; KDM4A overexpression had the opposite effects, and significantly blocked the regulation of miR-526b on cell growth and invasion. Therefore, circ_SPECC1 can enhance miR-526b inhibitory effect on downstream KDM4A/YAP1 pathway by adsorbing it, thus inhibiting GC cell growth and invasion. These findings enrich the mechanism of circRNAs in GC and will provide more new targets for the prevention and treatment of GC.

By downregulating PBX3, miR-526b suppresses the epithelial-mesenchymal transition process in cervical cancer cells.

Aim: Research on novel mutant genes may develop the treatment of cervical cancer (CC). The role of miRNA-526b in epithelial-mesenchymal transition (EMT) of CC was investigated. Methods: The role and the molecular mechanism of miRNA-526b in CC and its effect on EMT were analyzed in clinical specimens and oncology experiments. Results: miRNA-526b was proved to be decreased in CC and associated with malignant clinicopathological characters. The character of miRNA-526b in EMT was also inspected in CC cells and tumor models. miRNA-526b was found to be able to inhibit the EMT property of CC cells by directly targeting PBX3. Conclusion: miRNA-526b restoration may be deliberated as a new treatment strategy of CC.

miR526b and miR655 Induce Oxidative Stress in Breast Cancer.

In eukaryotes, overproduction of reactive oxygen species (ROS) causes oxidative stress, which contributes to chronic inflammation and cancer. MicroRNAs (miRNAs) are small, endogenously produced RNAs that play a major role in cancer progression. We established that overexpression of miR526b/miR655 promotes aggressive breast cancer phenotypes. Here, we investigated the roles of miR526b/miR655 in oxidative stress in breast cancer using in vitro and in silico assays. miRNA-overexpression in MCF7 cells directly enhances ROS and superoxide (SO) production, detected with fluorescence assays. We found that cell-free conditioned media contain extracellular miR526b/miR655 and treatment with these miRNA-conditioned media causes overproduction of ROS/SO in MCF7 and primary cells (HUVECs). Thioredoxin Reductase 1 (TXNRD1) is an oxidoreductase that maintains ROS/SO concentration. Overexpression of TXNRD1 is associated with breast cancer progression. We observed that miR526b/miR655 overexpression upregulates TXNRD1 expression in MCF7 cells, and treatment with miRNA-conditioned media upregulates TXNRD1 in both MCF7 and HUVECs. Bioinformatic analysis identifies two negative regulators of TXNRD1, TCF21 and PBRM1, as direct targets of miR526b/miR655. We validated that TCF21 and PBRM1 were significantly downregulated with miRNA upregulation, establishing a link between miR526b/miR655 and TXNRD1. Finally, treatments with oxidative stress inducers such as H2O2 or miRNA-conditioned media showed an upregulation of miR526b/miR655 expression in MCF7 cells, indicating that oxidative stress also induces miRNA overexpression. This study establishes the dynamic functions of miR526b/miR655 in oxidative stress induction in breast cancer.

Melatonin-mediated miR-526b-3p and miR-590-5p upregulation promotes chondrogenic differentiation of human mesenchymal stem cells.

Bone marrow-derived mesenchymal stem cells (BMSCs), with inherent chondrogenic differentiation potential appear to be ideally suited for therapeutic use in cartilage regeneration. Accumulating evidence has demonstrated that melatonin can promote chondrogenic differentiation in human BMSCs. However, little is known about the mechanism. MicroRNAs (miRNAs) have been shown to regulate the differentiation of BMSCs, but their roles in melatonin-promoted chondrogenic differentiation have not been characterized. Here, we demonstrate that melatonin promoted chondrogenic differentiation of human BMSCs via upregulation of miR-526b-3p and miR-590-5p. Mechanistically, the elevated miR-526b-3p and miR-590-5p enhanced SMAD1 phosphorylation by targeting SMAD7. Additionally, administration of miR-526b-3p mimics or miR-590-5p mimics successfully promoted the chondrogenic differentiation of human BMSCs. Collectively, our study suggests that modification of BMSCs using melatonin or miRNA transduction could be an effective therapy for cartilage damage and degeneration.

Breast cancer cell secretome analysis to decipher miRNA regulating the tumor microenvironment and discover potential biomarkers.

MicroRNA (miRNA/miR) 526 b- and miR655-overexpressed tumor cell-free secretions regulate the breast cancer tumor microenvironment (TME) by promoting tumor-associated angiogenesis, oxidative stress, and hypoxic responses. Additionally, premature miRNA (pri-miR526b and pri-miR655) are established breast cancer blood biomarkers. However, the mechanisms of how these miRNAs regulate the TME has yet to be investigated. Mass spectrometry analysis of miRNA-overexpressed cell lines MCF7-miR526b, MCF7-miR655, and miRNA-low MCF7-Mock cell-free secretomes identified 34 differentially expressed proteins coded by eight genes. In both miRNA-high cell secretomes, four markers are upregulated: YWHAB, SFN, TXNDC12, and MYL6B, and four are downregulated: PEA15, PRDX4, PSMB6, and FN1. All upregulated marker transcripts are significantly high in both total cellular RNA pool and cell-free secretions of miRNA-high cell lines, validated with quantitative RT-PCR. Bioinformatics tools were used to investigate these markers' roles in breast cancer. These markers' top gene ontology functions are related to apoptosis, oxidative stress, membrane transport, and motility supporting oncogenic miR526b- and miR655-induced functions. Gene transcription factor analysis tools were used to show how these miRNAs regulate the expression of each secretory marker. Data extracted from the Human Protein Atlas showed that YWHAB, SFN, and TXNDC12 expression could distinguish early and late-stage breast cancer in various breast cancer subtypes and are associated with poor patient survival. Additionally, immunohistochemistry analysis showed the expression of each marker in breast tumors. A stronger correlation between miRNA clusters and upregulated secretory markers gene expression was found in the luminal A tumor subtype. YWHAB, SFN, and MYL6B are upregulated in breast cancer patient's blood, showing biomarker potential. Of these identified novel miRNA secretory markers, SFN and YWHAB successfully passed all validations and are the best candidates to further investigate their roles in miRNA associated TME regulation. Also, these markers show the potential to serve as blood-based breast cancer biomarkers, especially for luminal-A subtypes.

Hsa_circ_0119412 is a tumor promoter in hepatocellular carcinoma by inhibiting miR-526b-5p to upregulate STMN1.

Hepatocellular carcinoma (HCC) is always deemed a deadly malignancy worldwide. Non-coding RNAs, including circRNAs, are becoming more widely recognized as essential regulators of the malignant development of HCC. Thus, we elaborated the regulating role of hsa_circ_0119412 in HCC advancement. The qRT-PCR was done to estimate the expressions of hsa_circ_0119412, miR-526b-5p, and Stathmin 1 (STMN1) in HCC (clinical samples and cell lines), and immunoblotting was used to detect STMN1 protein level in HCC cell lines. The stability of the circRNA was checked by processing with ribonuclease R. The proliferative potential of HCC cells was examined via the CCK-8 assay and the migratory potential by the wound healing assay. Immunoblotting was done to examine Bax and Bcl-2 (apoptosis-related proteins). Luciferase and RIP assays were employed to establish the direct interactions among miR-526b-5p and hsa_circ 0119412/STMN1. In vivo tumor growth was measured by doing a xenograft tumor experiment. In the tissues of HCC patients and cell lines derived from HCC cells, hsa_circ_0119412 was distinctly over-expressed. Knocking down hsa_circ_0119412 impeded proliferation and migration while inducing apoptosis in HCC cells. Moreover, silencing hsa_circ_0119412 diminished tumor weight and volume in vivo. Interestingly, miR-526b-5p inhibition partially restored the anti-tumor effects of silencing hsa_circ_0119412. STMN1 expression was also abundant in HCC, suggesting that it play a tumor-promoting role. Mechanistically, hsa_circ_0119412 sponged miR-526b-5p, resulting in STMN1 upregulation and thus facilitating the progression of HCC. In conclusion, this study reveals that hsa_circ_0119412 knockdown attenuates the progression of HCC by targeting miR-526b-5p/STMN1 axis.

Knockdown of long non-coding RNA LINC00941 suppressed cell proliferation, colony-formation, and migration of human glioblastoma cell lines.

INTRODUCTION: Glioblastoma (GBM) represents the most common and lethal type of primary brain tumour in adults, and due to its high invasiveness, treatment of GBM remains challenging. This work is aimed to elucidate the role of LINC00941 in GBM. MATERIAL AND METHODS: Expression of LINC00941 in two GBM cell lines U251 and U87-MG was knocked down using siRNA. Cell proliferation and colony-formation ability of LINC00941 knockdown were examined. Apoptosis of the knockdown was evaluated using flow cytometry, with the levels of Bax, Bcl-2, cleaved caspase-3, and phosphorylation of ERK and Akt to be examined using western blotting. Migration and invasion of the knockdown was studied using transwell assays. RESULTS: Expression of LINC00941 was significantly elevated in GBM compared to non-tumour tissues ( p < 0.01). Statistical analysis on the expression data further revealed the negative correlation between LINC00941 and miR-526b-5p ( r = 0.7494, p < 0.001). LINC00941 was successfully knocked down with RNA interference in U251 and U87-MG. The knockdown significantly suppressed cell proliferation and the ability to form colonies. Percentage of apoptotic cells was elevated by the knockdown in both cell lines as evidenced by flow cytometric analysis, which was accompanied by a significant decrease in Bcl-2 and substantial increases in Bax and cleaved caspase-3. Phosphorylation of ERK and Akt was also enhanced in both cell lines by the knockdown. In addition, knockdown of LINC00941 suppressed migration of both cell lines across transwell membrane and matrigel. CONCLUSIONS: LINC00941 is overexpressed in GBM, exhibiting important roles in cell proliferation and survival, migration and invasion.

MiR-526b-3p enhances sensitivity of head and neck squamous cell carcinoma cells to radiotherapy via suppressing exosomal LAMP3-mediated autophagy.

Lysosomal associated membrane protein 3 (LAMP3) has been reported to be a tumour promoter in multiple cancer types by modulating tumour cell autophagy. However, the potential mechanism of LAMP3 in radio-resistance of head and neck squamous cell carcinoma (HNSCC) remains unknown. Therefore, our current study aims to detect the impacts of LAMP3 on the resistance of HNSCC cells to radiotherapy and meanwhile explore its functional mechanism. Through RT-Qpcr examination, LAMP3 expression was identified to be expressed at a significantly high level in irradiation-resistant HNSCC cell lines compared with irradiation-sensitive HNSCC cell lines. Functional assays including CCK-8, colony formation and Transwell assays demonstrated that LAMP3 enhanced the radio-resistance through inducing autophagy to promote HNSCC cell growth. Furthermore, irradiation-resistant HNSCC cells could transfer exosomal LAMP3 to elevate LAMP3 expression in irradiation-sensitive HNSCC cells. Mechanistically, microRNA (miRNA) miR-526b-3p could inhibit LAMP3 expression so as to strengthen sensitivity of HNSCC cells to radiotherapy. In a word, exosomal LAMP3 expression promoted radioresistance of HNSCC cells via inducing autophagy, while this effect could be suppressed by miR-526b-3p in a targeted manner.

Hsa_circ_0001495 contributes to cervical cancer progression by targeting miR-526b-3p/TMBIM6/mTOR axis.

Cervical cancer (CC) is a common gynecological malignant tumor, causing poor survival rate. Circular RNAs (circRNAs) are abundantly expressed in CC with their stable loop structure. However, the underlying mechanism and biological function of circRNAs remained unclear. Using quantitative real-time polymerase chain reaction (qRT-PCR) or western blot assay, we measured the expression of hsa_circ_0001495, miR-526b-3p, and transmembrane Bax inhibitor motif containing 6 (TMBIM6) in CC tissues and cells. The relationship between miR-526b-3p and hsa_circ_0001495 or TMBIM6 was investigated by bioinformatics analysis, dual-luciferase and RIP analysis. Enzyme linked immunosorbent assay (ELISA) was conducted to evaluate glucose consumption and lactate production. 5-ethynyl-2'-deoxyuridine (EDU) assay were used to test cell proliferation. Cell apoptosis was analyzed by using flow cytometry assay. Transwell and wound-healing assays were used to measure cell invasion and migration. The expression of proteins was examined by western blot. Xenograft assay was applied to detect the effect of hsa_circ_0001495 in vivo. Our finding showed that hsa_circ_0001495 and TMBIM6 expression were upregulated, while miR-526b-3p was downregulated in CC tissues and cell lines. Hsa_circ_0001495 knockdown or TMBIM6 knockdown suppressed cell proliferation, migration, glycolysis, while promoted cell apoptosis in vitro, and hsa_circ_0001495 silence curbed tumor growth in vivo. Beside, hsa_circ_0001495 exerted its function in CC by positively regulating TMBIM6. Furthermore, hsa_circ_0001495 acted as a sponge for miR-526b-3p to regulate TMBIM6 expression. Hsa_circ_0001495/miR-526b-3p/TMBIM6 axis also regulated the phosphorylation of mammalian target of rapamycin (mTOR) in CC cells. In summary, hsa_circ_0001495 regulated the progression of CC by regulating miR-526b-3p/TMBIM6/mTOR pathway.

Circ_0001821 knockdown suppresses growth, metastasis, and TAX resistance of non-small-cell lung cancer cells by regulating the miR-526b-5p/GRK5 axis.

Non-small-cell lung cancer (NSCLC) remains a huge obstacle to human health. Certain circular RNAs endow with crucial regulatory roles in NSCLC progression. Here, we investigated the functional effects of circ_0001821 on cellular behaviors of NSCLC cells and explored the possible mechanism. The expression of circ_0001821, microRNA (miR)-526b-5p, and G protein-coupled receptor kinase 5 (GRK5) was determined by quantitative real-time polymerase chain reaction or Western blot assay. Clonogenicity in NSCLC cells was detected via colony formation assay. Cell migration and invasion were monitored by Transwell assay. Cell sensitivity to paclitaxel (TAX) evaluated by Cell Counting Kit-8 assay. Cell apoptosis was assessed by flow cytometry, caspase-3 activity, and caspase-9 activity. The targeted relationship between miR-526b-5p and circ_0001821 or GRK5 was confirmed by dual-luciferase reporter or RNA pull-down assay. Moreover, the role of circ_0001821 in vivo was examined by xenograft model assay. The results presented that the expression of circ_0001821 and GRK5 was increased, while miR-526b-5p expression was decreased in NSCLC tissues and cells. Circ_0001821 knockdown reduced colony formation ability and metastasis ability but enhanced TAX sensibility and apoptosis of NSCLC cells, which was attenuated by miR-526b-5p inhibition or GRK5 overexpression. Circ_0001821 targeted miR-526b-5p, and miR-526b-5p targeted GRK5. Circ_0001821 could upregulate GRK5 expression by sponging miR-526b-5p. Depletion of circ_0001821 also blocked tumor growth in vivo. In conclusion, the depletion of circ_0001821 inhibited NSCLC progression, at least in part, by modulating the miR-526b-5p/GRK5 axis.