CircPTPRA acts as a tumor suppressor in bladder cancer by sponging miR-636 and upregulating KLF9

Growing evidence suggests that circular RNAs (circRNAs) play pivotal roles in cancer progression. In this study, bioinformatic analysis identified a dysregulated circRNA termed circPTPRA in bladder cancer (BC). By using qRT-PCR analysis, we verified that circPTPRA is down-regulated in clinical BC specimens compared with the matched non-tumor samples, while correlation analyses showed that low circPTPRA expression is associated with poor prognosis, advanced tumor stage and larger tumor size. Based on these findings, we conducted functional assays and revealed that circPTPRA inhibits BC cell proliferation in vitro and tumor growth in vivo. In addition, RNA pull-down, miRNA capture, FISH, and luciferase reporter assays demonstrated that circPTPRA can directly sponge miR-636. Cell transfection experiments showed that miR-636 promotes the proliferation of BC cells by decreasing the expression of Krüppel Like Factor 9 (KLF9) upon binding to the 3’UTR of its mRNA.

Further analysis confirmed that circPTPRA competitively sponges miR-636 to upregulate the KLF9 expression, leading to decreased proliferation of BC cells. Our investigation indicates that circPTPRA acts as a tumor suppressor in BC, and suggests that this circRNA may be a novel prognostic biomarker and therapeutic target in BC.

Downregulation of circRNA_100876 Inhibited Progression of NSCLC In Vitro via Targeting miR-636

BACKGROUND

Non-small cell lung carcinoma (NSCLC) is a common malignant tumor with poor prognosis. CircRNA-100876 has been considered to be involved in NSCLC. However, the mechanism by which circRNA_100876 mediated the progression of NSCLC remains unclear.

METHODS

CCK8 assay and immunofluorescence were used to detect cell proliferation. Flow cytometry and transwell assay were performed to analyze cell apoptosis, migration and invasion, respectively. Verification of possible target for circRNA_100876 and related miR-636 were done using luciferase assay. In addition, western blot was performed to detect the protein expressions in NSCLC cells.

RESULTS

Silencing of circRNA_100876 notably inhibited the proliferation of NSCLC cells. Moreover, downregulation of circRNA_100876 significantly induce the apoptosis of NSCLC cells via mediation of apoptosis-related proteins. In addition, silencing of circRNA_100876 significantly inhibited migration and invasion of NSCLC cells. MiR-636 was the downstream target of circRNA_100876. Meanwhile, RET was the direct target of miR-636. Finally, circRNA_100876 shRNA2 notably suppressed the progression of NSCLC through PI3K/Akt signaling.

CONCLUSION

CircRNA_100876 knockdown notably suppressed the progression of NSCLC through regulation of miR-636/RET axis, which may serve as a potential target for treatment of NSCLC.

circCELF1 Inhibits Myocardial Fibrosis by Regulating the Expression of DKK2 Through FTO/m6A and miR-636

The aim of this study is to explore the role of circCELF1/miR-636/DKK2 pathway in myocardial fibrosis (MF). RT-qPCR and western blot were used to detect the expression of circCELF1, miR-636, and DKK2 in activated cardiac fibroblasts (CFs) and the hearts of acute myocardial infarction (AMI) mice. The m⁶A level of DKK2 was detected by RIP and RT-qPCR. The regulation of circCELF1/miR-636/DKK2 pathway on CF viability, activation, apoptosis, and migration was verified by CCK-8, western blot, flow cytometry, and Transwell. Ang II induced downregulation of circCELF1 expression, while circCELF1 enhanced the expression of DKK2 by adsorbing miR-636. circCELF1 also reduced DKK2 m⁶A level by upregulating FTO expression, thereby inhibiting the binding of miR-636 to DKK2 and promoting DKK2 expression. Ang II promoted CF viability, activation, and migration through the circCELF1/miR-636/DKK2 pathway. Both miR-636 inhibitors and DKK2 effectively reduced MF and improved cardiac function in AMI mice.

miR-636 inhibits EMT, cell proliferation and cell cycle of ovarian cancer by directly targeting transcription factor Gli2 involved in Hedgehog pathway

Background

Hedgehog (Hh) signaling pathway, which is essential for cell proliferation and differentiation, is noted to be aberrantly activated in tumor from increasing studies in recent years. MicroRNAs (miRNAs) as an important non-coding RNA in cells have been proven to possess a regulatory role specific to the Hh signaling pathway. Here, in vitro and in vivo cellular/molecular experiments were adopted to clarify the regulatory mechanism linking miR-636 to the Hh signaling pathway in ovarian cancer (OVC).

Methods

Protein–protein interaction analysis was performed to identify the hub gene in the Hh pathway. TargetScan database was used to predict the potential upstream regulators for Gli2. qRT-PCR was performed to test the expression of miR-636, while Western blot was conducted to detect the expression of proteins related to the Hh pathway and epithelial-mesenchymal transition (EMT). For cell functional experiments, HO-8910PM OVC cell line was used. MTT assay and wound healing assay were used to measure the effect of miR-636 on cell proliferation and migration. Flow cytometry was carried out to examine the effect of miR-636 on cell cycle, and Western blot was used to identify the change in expression of Hh and EMT-related proteins. Dual-luciferase reporter gene assay was implemented to detect the targeting relationship between miR-636 and Gli2. Xenotransplantation models were established for in vivo examination.

Results

Gli2 was identified as the hub gene of the Hh pathway and it was validated to be regulated by miR-636 based on the data from TargetScan and GEO databases. In vitro experiments discovered that miR-636 was significantly lowly expressed in OVC cell lines, and overexpressing miR-636 significantly inhibited HO-8910PM cell proliferation, migration and induced cell cycle arrest in G0/G1 phase, while the inhibition of miR-636 caused opposite results. Dual-luciferase reporter gene assay revealed that Gli2 was the target gene of miR-636 in OVC. Besides, overexpressed miR-636 decreased protein expression of Gli2, and affected the expression of proteins related to the Hh signaling pathway and EMT. Rescue experiments verified that overexpression of Gli2 reversed the inhibitory effect of miR-636 on HO-8910PM cell proliferation and migration, and attenuated the blocking effect of miR-636 on cell cycle. The xenotransplantation experiment suggested that miR-636 inhibited cell growth of OVC by decreasing Gli2 expression. Besides, overexpressing Gli2 potentiated the EMT process of OVC cells via decreasing E-cadherin protein expression and increasing Vimentin protein expression, and it reversed the inhibitory effect of miR-636 on OVC cell proliferation in vivo.

Conclusion

miR-636 mediates the activation of the Hh pathway via binding to Gli2, thus inhibiting EMT, suppressing cell proliferation and migration of OVC.

Trial registration: The experimental protocol was established, according to the ethical guidelines of the Helsinki Declaration and was approved by the Human Ethics Committee of The Second Affiliated hospital of Zhejiang University School of Medicine (IR2019001235). Written informed consent was obtained from individual or guardian participants.

Circ_0010235 facilitates lung cancer development and immune escape by regulating miR-636/PDL1 axis

Background

Circular RNAs (circRNAs) are a class of important regulators in various human cancers, including lung cancer. Here, we aimed to investigate the role of circ_0010235 in lung cancer.

Methods

The expression of circ_0010235, microRNA‐636 (miR‐636) and PDL1 was measured by quantitative real‐time PCR (qRT‐PCR). Cell proliferation was evaluated by CCK‐8, colony formation, and 5‐ethynyl‐2′‐deoxyuridine (EdU) assays. Cell apoptosis was detected by flow cytometry. Cell invasion was assessed by transwell assay. All protein levels were determined by western blot assay. In order to detect the roles of circ_0010235 in immune escape, lung cancer cells were cocultured with peripheral blood mononuclear cells (PBMCs) or cytokine‐induced killer (CIK) cells in vitro. The relationship between miR‐636 and circ_0010235 or PDL1 was verified by dual‐luciferase reporter assay and RNA pulldown assay. Immunohistochemistry (IHC) analysis was used to detect Ki67 and programmed death‐ligand 1 (PDL1) expression. A xenograft tumor model was established to verify the function of circ_0010235 in vivo.

Results

Circ_0010235 was overexpressed in lung cancer. Circ_0010235 knockdown inhibited proliferation, invasion and immune escape and promoted apoptosis of lung cancer cells. MiR‐636 was a target of circ_0010235, and miR‐636 inhibition reversed the effects of circ_0010235 knockdown in lung cancer cells. PDL1 was a direct target of miR‐636, and miR‐636 suppressed the proliferation and invasion and increased apoptosis and antitumor immunity in lung cancer cells by downregulating PDL1. Moreover, circ_0010235 positively regulated PDL1 expression by sponging miR‐636. Additionally, circ_0010235 knockdown hampered tumorigenesis in vivo.

Conclusion

Circ_0010235 knockdown inhibited lung cancer progression and increased antitumor immunity by regulating the miR‐636/PDL1 axis.

Circular RNA circ_0023404 serves as a miR-636 sponge to promote malignant behaviors in cervical cancer cells through upregulation of CYP2S1

Cervical cancer is the most common malignant gynecological tumor. Circular RNA (circRNA) circ_0023404 is reported to be upregulated in cervical cancer cells. This aim is to explore the role and mechanism of circ_0023404 in cervical cancer. circ_0023404, microRNA-636 (miR-636), and cytochrome P450 2S1 (CYP2S1) levels were detected by real-time quantitative polymerase chain reaction (RT-qPCR). Cell proliferation, migration, invasion, and apoptosis were detected by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay, 5-ethynyl-2'-deoxyuridine (EDU) assay, colony formation assay, transwell assay, and cytometry assay. Protein levels of cyclin D1, matrix metallopeptidase 9 (MMP9), Bcl-2-associated X protein (Bax), and CYP2S1 were examined by western blot assay. The binding relationship between miR-636 and circ_0023404 or CYP2S1 was predicted by Circinteractome or targetscan, and then verified by a dual-luciferase reporter assay and RNA pull-down assay. circ_0023404 and CYP2S1 expression were increased, and miR-636 was decreased in cervical cancer tissues and cells. Moreover, circ_0023404 knockdown could repress proliferation, migration, invasion, and promote apoptosis of cervical cancer cells in vitro. Mechanically, circ_0023404 could regulate CYP2S1 expression by sponging miR-636. circ_0023404 silencing could attenuate the progression of cervical cancer cells partly by targeting the miR-636/CYP2S1 axis, hinting at a promising therapeutic target for cervical cancer.

Circ_0005736 promotes tenogenic differentiation of tendon-derived stem cells through the miR-636/MAPK1 axis

BACKGROUND

Tendon-derived stem cells (TDSCs) are one of stem cells characterized by greater clonogenicity, tenogenesis, and proliferation capacity. Circ_0005736 has been shown to be decreased in Rotator cuff tendinopathy. Here, we investigated the function and relationship of circ_0005736 in TDSC tenogenic differentiation.

METHODS

Transforming growth factor β1 (TGF-β1) was used to induce the tenogenic differentiation in TDSC. Cell proliferation, invasion and migration were evaluated by Cell Counting Kit-8, 5-Ethynyl-2'-deoxyuridine, transwell, and wound healing assays, respectively. The detection of the levels of genes and proteins was performed by qRT-PCR and Western blot. The binding between miR-636 and circ_0005736 or MAPK1 (Mitogen-Activated Protein Kinase 1) was verified using dual-luciferase reporter assay and RIP assays.

RESULTS

TGF-β1 induced tenogenic differentiation by enhancing the production of tendon-specific markers and TDSC proliferation, invasion and migration. TGF-β1 treatment promoted circ_0005736 expression, knockdown of circ_0005736 abolished TGF-β1-induced tenogenic differentiation in TDSCs. Mechanistically, circ_0005736 acted as a sponge for miR-636 to up-regulate the expression of MAPK1, which was confirmed to be a target of miR-636 in TDSCs. Further rescue assays showed that inhibition of miR-636 could rescue circ_0005736 knockdown-induced suppression on TGF-β1-caused tenogenic differentiation in TDSCs. Moreover, forced expression of miR-636 abolished TGF-β1-caused tenogenic differentiation in TDSCs, which was rescued by MAPK1 up-regulation.

CONCLUSION

Circ_0005736 enhanced TGF-β1-induced tenogenic differentiation in TDSCs via increasing the production of tendon-specific markers and TDSC proliferation, invasion and migration through miR-636/MAPK1 axis.

IRF4 suppresses osteogenic differentiation of BM-MSCs by transcriptionally activating miR-636/DOCK9 axis

OBJECTIVES

Osteoblasts are derived from Bone Marrow-derived Mesenchymal Stem Cells (BM-MSCs), which play an indispensable role in bone formation. In this study, the authors aim to investigate the role of IRF4 in the osteogenic differentiation of BM-MSCs and its potential molecular mechanism.

METHODS

The authors used lentivirus infection to overexpress IRF4 in BM-MSCs. The expression of IRF4 and osteogenesis-related genes were detected by qRT-PCR and western blot analysis. The osteogenic differentiation of BM-MSCs was evaluated by Alkaline Phosphatase (ALP) activity, Alizarin red staining, and Alkaline Phosphatase (ALP) staining. Chromatin Immunoprecipitation (ChIP), Dual-Luciferase reporter assay and RNA Immunoprecipitation Assay were applied to confirm the regulatory mechanism between IRF4, miR-636 and DOCK9.

RESULTS

The authors found IRF4 was down-regulated during the osteogenic differentiation of BM-MSCs, and IRF4 overexpression could decrease the osteogenic differentiation of BM-MSCs by specifically promoting the reduction of Alkaline Phosphatase (ALP) activity and down-regulating osteogenic indicators, including OCN, OPN, Runx2 and CollA1. Mechanistically, IRF4 activated microRNA-636 (miR-636) expression via binding to its promoter region, and Dedicator of Cytokinesis 9 (DOCK9) was identified as the target of miR-636 in BM-MSCs. Moreover, the damage in the capacity of osteogenic differentiation of BM-MSCs induced by IRF4 overexpression could be rescued by miR-636 inhibition.

CONCLUSIONS

In summary, this paper proposed that IRF4/miR-636/DOCK9 may be considered as targets for the treatment of osteoporosis (OP).

Circ_0025039 acts an oncogenic role in the progression of non-small cell lung cancer through miR-636-dependent regulation of CORO1C

Non-small cell lung cancer remains the leading cause of cancer-related death worldwide. Circular RNA plays vital roles in NSCLC progression. This study is designed to reveal the role of circ_0025039 in NSCLC cell malignancy. The RNA expression of circ_0025039, microRNA-636 (miR-636), and coronin 1C was detected by quantitative real-time polymerase chain reaction. Protein expression was checked by Western blot analysis or immunohistochemistry assay. Cell proliferation, migration, invasion, tube formation ability, sphere formation capacity, and apoptosis were investigated by cell counting kit-8, 5-Ethynyl-29-deoxyuridine, transwell assay, tube formation assay, sphere formation assay, and flow cytometry analysis, respectively. Mouse model assay was conducted to reveal the effect of circ_0025039 silencing on tumor formation in vivo. The interaction between miR-636 and circ_0025039 or CORO1C was identified through dual-luciferase reporter and RNA pull-down assays. The expression of circ_0025039 and CORO1C was significantly increased, while miR-636 was decreased in NSCLC tissues and cells compared with controls. Circ_0025039 depletion repressed NSCLC cell proliferation, migration, invasion, tube-forming capacity, and sphere formation ability, but induced cell apoptosis. The neoplasm formation was repressed after circ_0025039 silencing. Additionally, circ_0025039 acted as a sponge for miR-636, which was found to target CORO1C. Importantly, the contribution of circ_0025039 to NSCLC progression was mediated by miR-636/CORO1C axis. Circ_0025039 silencing repressed NSCLC malignant progression by reducing CORO1C expression through miR-636, showing the possibility of circ_0025039 as a therapeutic target for NSCLC.

Predictive value of miR-636 in patients with acute myocardial infarction undergoing percutaneous coronary intervention and its bioinformatics analysis

BACKGROUND

MicroRNAs (miRNAs) play an important role in the pathogenesis of cardiovascular diseases such as acute myocardial infarction (AMI). Percutaneous coronary intervention (PCI) is currently the most direct and effective procedure to treat AMI, but the occurrence of postoperative cardiovascular events (MACE) affects patients' quality of life. The objective of this study was to identify a new biomarker that could provide a theoretical basis for the prevention of MACE in patients with AMI undergoing PCI.

METHODS

142 AMI patients who underwent PCI and 130 healthy volunteers were selected as study subjects. Detection of miR-636 expression level by fluorescence quantitative PCR. ROC, Kaplan-Meier and Cox regression analyses were applied to evaluate the diagnostic and prognostic value of miR-636 for AMI. The miR-636 target genes were predicted and enriched for GO function and KEGG pathway.

RESULTS

MiR-636 expression levels were elevated in patients with AMI. ROC curve analysis showed that miR-636 had a feasible diagnostic value in distinguishing AMI patients from healthy controls miR-636 expression levels were elevated in patients who developed MACEs. ROC results showed that miR-636 had significant diagnostic value in differentiating AMI patients with and without MACEs after PCI treatment. GO and KEGG enrichment analyses showed that miR-636 may transmit information to vesicles formed by the cell membrane.

CONCLUSIONS

MiR-636 expression serves as a biomarker for diagnosing AMI and predicting the occurrence of MACE after PCI.