Elevated levels of hsa_circ_006100 in gastric cancer promote cell growth and metastasis via miR-195/GPRC5A signalling

GPRC5A promotes paclitaxel resistance and glucose content in NSCLC

Lung cancer is one of the most common and malignant cancers worldwide. Chemotherapy has been widely used in the clinical setting, and paclitaxel is the first-line therapy for lung cancer patients but paclitaxel resistance is the main problem. First, we successfully established paclitaxel-resistant lung cancer cells treated with elevated doses of paclitaxel for 3 months, as confirmed by the CCK-8 assay. Paclitaxel-resistant cancer cells increased glucose content. Second, Gtex, Oncomine, and gene expression omnibus database data mining identified GPRC5A, G protein-coupled receptor, as the most prominent differentially expressed gene in drug-resistant datasets including gemcitabine, paclitaxel, and gefitinib overlapped with the microarray data from cancer cell metabolism. Third, qPCR analysis and western blot technique showed that GPRC5A mRNA and protein levels were significantly enhanced in paclitaxel-resistant lung cancer cells. Fourth, functional analysis was conducted by siRNA-mediated transient knockdown of GPRC5A. Silencing GPRC5A significantly decreased paclitaxel resistance and glucose content. In the end, retinoic acid substantially upregulated GPRC5A proteins and promoted glucose content in two lung cancer cells. Kaplan-Meier plot also confirmed that lung cancer patients with high expression of GPRC5A had a relatively lower survival rate. Our study provided a potential drug target GPRC5A, which may benefit lung cancer patients with acquired paclitaxel resistance in the future and a theoretical basis for future preclinical trials.

GPRC5A promotes gallbladder cancer metastasis by upregulating TNS4 via the JAK2-STAT3 pathway

Aberrant expression of G protein-coupled receptor class C group 5 member A (GPRC5A) has been reported in multiple cancers and is closely related to patient prognosis. However, the mechanistic role of GPRC5A in gallbladder cancer (GBC) remains unclear. Here, we determined tumor expression levels of GPRC5A and the molecular mechanisms by which GPRC5A regulates gallbladder cancer metastasis. We found that GPRC5A was significantly upregulated in GBC, correlating with poorer patient survival. Knocking down GPRC5A inhibited GBC cell metastasis both in vitro and in vivo. GRPRC5A knockdown resulted in downregulation of TNS4 expression through the JAK2-STAT3 axis. Clinically, GPRC5A expression positively correlated with TNS4. Finally, STAT3 bound to TNS4's promoter region, inducing its expression. Overall, GPRC5A showed high expression in GBC tissues, associated with poor patient prognosis. Our findings first demonstrate that the GPRC5A-JAK2-STAT3-TNS4 pathway promotes GBC cell metastasis, suggesting potential therapy targets.

Circ_PABPC1 promotes the malignancy of gastric cancer through interacting with ILK to activate NF-κB pathway

BACKGROUND

Gastric cancer (GC) is a common cancer type with both high incidence and mortality. Recent studies have revealed an important role of circRNA in the development of GC. However, more experiments are needed to reveal the precise molecular mechanisms of circRNA in GC development.

METHODS

Bioinformatics analysis was conducted to predict the potential role of circ_PABPC1 in GC and the target proteins of circ_PABPC1. Quantitative RT-PCR, Western blot and immunohistochemistry assays were conducted to detect the levels of circ_PABPC1, NF-κB p65, NF-κB p65 (Ser536) and ILK. MTT, Edu staining, cell scratch-wound and trans-well assays were carried out to detect cell proliferation, migration and invasion. The interaction between ILK and circ_PABPC1 was confirmed by RNA immunoprecipitation (RIP), RNA pull-down and fluorescence in situ hybridization assays. Genetically modified GC cells were injected into mice to evaluate the tumor growth performance.

RESULTS

This study found that the high expression of circ_PABPC1 was associated with a poor prognosis of GC. The up-regulation of circ_PABPC1 promoted the proliferation, migration and invasion of GC cells. Circ_PABPC1 bound to ILK protein, thereby preventing the degradation of ILK. ILK mediated the effect of circ_PABPC1 on GC cells through activating NF-κB.

CONCLUSION

circ_PABPC1 promotes the malignancy of GC cells through binding to ILK to activate NF-κB signaling pathway.

Circular RNAs in EMT-driven metastasis regulation: modulation of cancer cell plasticity, tumorigenesis and therapy resistance

The non-coding RNAs comprise a large part of human genome lack of capacity in encoding functional proteins. Among various members of non-coding RNAs, the circular RNAs (circRNAs) have been of importance in the pathogenesis of human diseases, especially cancer. The circRNAs have a unique closed loop structure and due to their stability, they are potential diagnostic and prognostic factors in cancer. The increasing evidences have highlighted the role of circRNAs in the modulation of proliferation and metastasis of cancer cells. On the other hand, metastasis has been responsible for up to 90% of cancer-related deaths in patients, requiring more investigation regarding the underlying mechanisms modulating this mechanism. EMT enhances metastasis and invasion of tumor cells, and can trigger resistance to therapy. The cells demonstrate dynamic changes during EMT including transformation from epithelial phenotype into mesenchymal phenotype and increase in N-cadherin and vimentin levels. The process of EMT is reversible and its reprogramming can disrupt the progression of tumor cells. The aim of current review is to understanding the interaction of circRNAs and EMT in human cancers and such interaction is beyond the regulation of cancer metastasis and can affect the response of tumor cells to chemotherapy and radiotherapy. The onco-suppressor circRNAs inhibit EMT, while the tumor-promoting circRNAs mediate EMT for acceleration of carcinogenesis. Moreover, the EMT-inducing transcription factors can be controlled by circRNAs in different human tumors.

CircPRDM5 inhibits the proliferation, migration, invasion, and glucose metabolism of gastric cancer cells by reducing GCNT4 expression in a miR-485-3p-dependent manner

Circular RNA (circRNA) plays a key part in the pathological process of gastric cancer (GC). The study is organized to analyze the function of circPRDM5 in GC cell tumor properties. Expression levels of circPRDM5, miR-485-3p, glucosaminyl (N-acetyl) transferase 4 (GCNT4), ki67, E-cadherin, N-cadherin, and hexokinase 2 (HK2) were analyzed by quantitative real-time polymerase chain reaction (PCR), Western blotting or immunohistochemistry assay. Cell proliferation was assessed by cell colony formation assay and 5-ethynyl-2'-deoxyuridine assay. Cell migration and invasion were investigated by transwell assay. Glycolysis was evaluated by the Seahorse XF Glycolysis Stress Test Kit. Dual-luciferase reporter assay and RNA pull-down assay were performed to identify the associations among circPRDM5, miR-485-3p, and GCNT4. Xenograft mouse model assay was conducted to determine the effects of circPRDM5 on tumor formation in vivo. CircPRDM5 and GCNT4 expression were downregulated, while miR-485-3p expression was upregulated in GC tissues and cells when compared with paracancerous tissues or human gastric epithelial cells. CircPRDM5 overexpression inhibited proliferation, migration, invasion, and glucose metabolism of GC cells; however, circPRDM5 depletion had the opposite effects. CircPRDM5 repressed tumor properties of GC cells in vivo. MiR-485-3p restoration relieved circPRDM5-induced effects in GC cells. GCNT4 overexpression remitted the promoting effects of miR-485-3p mimics on GC cell malignancy. CircPRDM5 acted as a sponge for miR-485-3p, and GCNT4 was identified as a target gene of miR-485-3p. Moreover, circPRDM5 regulated GCNT4 expression by interacting with miR-485-3p.CircPRDM5 acted as a miR-485-3p sponge to inhibit GC progression by increasing GCNT4 expression, proving a potential target for GC therapy.

The G protein-coupled receptor GPRC5A-a phorbol ester and retinoic acid-induced orphan receptor with roles in cancer, inflammation, and immunity

GPRC5A is the first member of a new class of orphan receptors coupled to G proteins, which also includes GPRC5B, GPRC5C, and GPRC5D. Since its cloning and identification in the 1990s, substantial progress has been made in understanding the possible functions of this receptor. GPRC5A has been implicated in a variety of cellular events, such as cytoskeleton reorganization, cell proliferation, cell cycle regulation, migration, and survival. It appears to be a central player in different pathological processes, including tumorigenesis, inflammation, immune response, and tissue damage. The levels of GPRC5A expression differ depending on the type of cancer, with increased expression in colon, pancreas, and prostate cancers; decreased expression in lung cancer; and varied results in breast cancer. In this review, we discuss the early discovery of GPRC5A as a phorbol ester-induced gene and later as a retinoic acid-induced gene, its regulation, and its participation in important canonical pathways related to numerous types of tumors and inflammatory processes. GPRC5A represents a potential new target for cancer, inflammation, and immunity therapies.

miRNA/epithelial-mesenchymal axis (EMT) axis as a key player in cancer progression and metastasis: A focus on gastric and bladder cancers

The metastasis a major hallmark of tumors that its significant is not only related to the basic research, but clinical investigations have revealed that majority of cancer deaths are due to the metastasis. The metastasis of tumor cells is significantly increased due to EMT mechanism and therefore, inhibition of EMT can reduce biological behaviors of tumor cells and improve the survival rate of patients. One of the gaps related to cancer metastasis is lack of specific focus on the EMT regulation in certain types of tumor cells. The gastric and bladder cancers are considered as two main reasons of death among patients in clinical level. Herein, the role of EMT in regulation of their progression is evaluated with a focus on the function of miRNAs. The inhibition/induction of EMT in these cancers and their ability in modulation of EMT-related factors including ZEB1/2 proteins, TGF-β, Snail and cadherin proteins are discussed. Moreover, lncRNAs and circRNAs in crosstalk of miRNA/EMT regulation in these tumors are discussed and final impact on cancer metastasis and response of tumor cells to the chemotherapy is evaluated. Moreover, the impact of miRNAs transferred by exosomes in regulation of EMT in these cancers are discussed.

ATG9A modulated by miR-195-5p can boost the malignant progression of cervical cancer cells

Cervical cancer (CC) is a major public health problem, and its molecular mechanism requires further investigation. The goal of this study was to determine the role of miR-195-5p and the autophagy-related protein ATG9A in tumour metastasis, epithelial - mesenchymal transition (EMT), apoptosis, and autophagy of CC cells. Using bioinformatics analysis, we predicted ATG9A as a downstream target gene of miR-195-5p, an integral membrane protein required for autophagosome formation and involved in tumorigenesis. Next, western blotting and Quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) showed that upregulation of miR-195-5p decreased protein and mRNA expression of ATG9A, and downregulation of miR-195-5p promoted ATG9A protein and mRNA expression. In addition, detection of the dual luciferase reporter gene further indicated ATG9A is a direct downstream target gene of miR-195-5p. Finally, the effects of miR-195-5p and ATG9A on CC cell proliferation, migration, invasion, EMT, autophagy, and apoptosis were evaluated in vitro. Our results showed that upregulation of miR-195-5p not only inhibits proliferation, migration, and the EMT of CC cells, but also induces apoptosis and autophagy. Conversely, downregulation of miR-195-5p increased malignant metastasis and the EMT of CC cells, and inhibited apoptosis as well as autophagy. In addition, miR-195-5p targeted and negatively regulated ATG9A, and rescue experiments suggested that overexpression of ATG9A could partially abolish miR-195-5p-mediated suppression of CC cells. Our findings improve our understanding of the mechanism of action of miR-195-5p in the malignant behaviour of CC. miR-195-5p is likely to be a promising cancer suppressor gene, which provides clinical evidence for targeted therapy of CC.

Dampening HOTAIR sensitizes the gastric cancer cells to oxaliplatin through miR-195-5p and ABCG2 pathway

Long non-coding RNAs (lncRNA) have an extensive role in the progression and chemoresistance of gastric cancer (GC). Deeply study the regulatory role of lncRNAs could provide potential therapeutic targets. The aim of this study is to explore the regulatory role of HOTAIR in the progression and oxaliplatin resistance of GC. The expression of HOTAIR in GC and cell lines were detected by using qRT-PCR. Cell proliferation and apoptosis were analysed by CCK-8, EdU incorporation and flow cytometry. Luciferase reporter assay was used to identify the interaction between HOTAIR and ABCG2 (ATP-binding cassette (ABC) superfamily G member 2, ABCG2) via miR-195-5p. The regulatory functions were verified by using molecular biology experiments. HOTAIR was significantly overexpressed in GC and associated with poor prognosis. Knock-down of HOTAIR inhibited the GC cells proliferation and oxaliplatin resistance, while overexpression of HOTAIR showed opposite functions. Further studies found that HOTAIR acted as a competing endogenous RNA (ceRNA) to absorb miR-195-5p and elevated the expression of ABCG2, which leads to resistance of GC cells to oxaliplatin. Taken together, our findings demonstrated that HOTAIR regulates ABCG2 induced resistance of GC to oxaliplatin through miR-195-5p signalling and illustrate the great potential of developing new therapeutic targets for GC patients.

Linc-ROR Promotes EMT by Targeting miR-204-5p/SMAD4 in Endometriosis

Endometriosis (EMs) is a systemic and chronic disease with cancer-like feature, namely, distant implantation, which caused heavy healthy burden of nearly 200 million females. LncRNAs have been proved as new modulators in epithelial-mesenchymal transition (EMT) and EMs. Quantitative real-time PCR was conducted to measure the expression level of long intergenic non-protein coding RNA, regulator of reprogramming (Linc-ROR), and miR-204-5p in ectopic endometrium (n = 25), eutopic endometrium (n = 20), and natural control endometrium (n = 22). Overexpression of Linc-ROR, knockdown or overexpression of miR-204-5p in End1/E6E7 and Ishikawa cells, was conducted to detect the function of Linc-ROR and miR-204-5p in EMs. Furthermore, luciferase reports were used to confirm the combination of Linc-ROR and miR-204-5p and the combination between miR-204-5p and SMAD4. Cell-Counting Kit-8, EdU assay, transwell assays, and Western blotting were used to detect the function of Linc-ROR and miR-204-5p in EMs cancer-like behaviors and EMT process. Linc-ROR was up-regulated in ectopic endometrium. Overexpressed Linc-ROR promotes cell proliferation, invasion, and EMT process. Linc-ROR regulated the EMT process, cellular proliferation, and invasion of EMs via binding to miR-204-5p. In addition, overexpression of Linc-ROR up-regulated SMAD4, a target protein of miR-204-5p, with which regulated EMT process and cancer-like behaviors in EMs together. Linc-ROR/miR-204-5p/SMAD4 axis plays a vital role in regulation EMT process in EMs, which might become a novel therapeutic targets and powerful biomarkers in EMs therapy.

An epigenetic modulator with promising therapeutic impacts against gastrointestinal cancers: A mechanistic review on microRNA-195

Due to their high prevalence, gastrointestinal cancers are one of the key causes of cancer-related death globally. The development of drug-resistant cancer cell populations is a major factor in the high mortality rate, and it affects about half of all cancer patients. Because of advances in our understanding of cancer molecular biology, non-coding RNAs (ncRNAs) have emerged as critical factors in the initiation and development of gastrointestinal cancers. Gene expression can be controlled in several ways by ncRNAs, including through epigenetic changes, interactions between microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) and proteins, and the function of lncRNAs as miRNA precursors or pseudogenes. As lncRNAs may be detected in the blood, circulating ncRNAs have emerged as a promising new class of non-invasive cancer biomarkers for use in the detection, staging, and prognosis of gastrointestinal cancers, as well as in the prediction of therapy efficacy. In this review, we assessed the role lncRNAs play in the progression, and maintenance of colorectal cancer, and how they might be used as therapeutic targets in the future.

Comparison of Oncogenes, Tumor Suppressors, and MicroRNAs Between Schizophrenia and Glioma: The Balance of Power

The risk of cancer in schizophrenia has been controversial. Confounders of the issue are cigarette smoking in schizophrenia, and antiproliferative effects of antipsychotic medications. The author has previously suggested comparison of a specific cancer like glioma to schizophrenia might help determine a more accurate relationship between cancer and schizophrenia. To accomplish this goal, the author performed three comparisons of data; the first a comparison of conventional tumor suppressors and oncogenes between schizophrenia and cancer including glioma. This comparison determined schizophrenia has both tumor-suppressive and tumor-promoting characteristics. A second, larger comparison between brain-expressed microRNAs in schizophrenia with their expression in glioma was then performed. This identified a core carcinogenic group of miRNAs in schizophrenia offset by a larger group of tumor-suppressive miRNAs. This proposed "balance of power" between oncogenes and tumor suppressors could cause neuroinflammation. This was assessed by a third comparison between schizophrenia, glioma and inflammation in asbestos-related lung cancer and mesothelioma (ALRCM). This revealed that schizophrenia shares more oncogenic similarity to ALRCM than glioma.

Circular RNAs as the pivotal regulators of epithelial-mesenchymal transition in gastrointestinal tumor cells

Gastrointestinal (GI) cancers, as the most common human malignancies are always considered one of the most important health challenges in the world. Late diagnosis in advanced tumor stages is one of the main reasons for the high mortality rate and treatment failure in these patients. Therefore, investigating the molecular pathways involved in GI tumor progression is required to introduce the efficient markers for the early tumor diagnosis. Epithelial-mesenchymal transition (EMT) is one of the main cellular mechanisms involved in the GI tumor metastasis. Non-coding RNAs (ncRNAs) are one of the main regulatory factors in EMT process. Circular RNAs (circRNAs) are a group of covalently closed loop ncRNAs that have higher stability in body fluids compared with other ncRNAs. Considering the importance of circRNAs in regulation of EMT process, in the present review we discussed the role of circRNAs in EMT process during GI tumor invasion. It has been reported that circRNAs mainly affect the EMT process through the regulation of EMT-specific transcription factors and signaling pathways such as WNT, PI3K/AKT, TGF-β, and MAPK. This review can be an effective step in introducing a circRNA/EMT based diagnostic panel marker for the early tumor detection among GI cancer patients.

Circular RNAs: implications of signaling pathways and bioinformatics in human cancer

Circular RNAs (circRNAs) form a class of endogenous single-stranded RNA transcripts that are widely expressed in eukaryotic cells. These RNAs mediate post-transcriptional control of gene expression and have multiple functions in biological processes, such as transcriptional regulation and splicing. They serve predominantly as microRNA sponges, RNA-binding proteins, and templates for translation. More importantly, circRNAs are involved in cancer progression, and may serve as promising biomarkers for tumor diagnosis and therapy. Although traditional experimental methods are usually time-consuming and laborious, substantial progress has been made in exploring potential circRNA-disease associations by using computational models, summarized signaling pathway data, and other databases. Here, we review the biological characteristics and functions of circRNAs, including their roles in cancer. Specifically, we focus on the signaling pathways associated with carcinogenesis, and the status of circRNA-associated bioinformatics databases. Finally, we explore the potential roles of circRNAs as prognostic biomarkers in cancer.

CircRNA PVT1 modulated cell migration and invasion through Epithelial-Mesenchymal Transition (EMT) mediation in gastric cancer through miR-423-5p/Smad3 pathway

Background

Gastric cancer (GC) progression is related with gene regulations.

Objectives

This study explored underlying regulatory axis of circRNA PVT1 (circPVT1) in GC.

Methods

GC cell lines were detected for circPVT1 expression with the normal mucous epithelial cell GES-1 as control. After regulation of circPVT1, miR-423-5p and SMAD3 expression through transfection, CCK8 evaluated the cell viability, Transwell measured the migratory and invasive capability of cells. Luciferase verified the paired bindings between miR-423-5p and CircPVT1 or SMAD3. The functions of CircPVT1/miR-423-5p/SMAD3 were evaluated using RT-PCR, CCK8, Transwell assays. Western blot analyzed EMT-related proteins and phosphorylation of Smad3 in GC cells. Immunofluorescence method was used to evaluate the EMT-related proteins as well.

Results

CircPVT1 displayed higher expression in GC cells and knockdown led to decrease in cell growth, invasion and migration. CircPVT1 was targeted by miR-423-5p as a ceRNA of SMAD3. miR-423-5p upregulation suppressed both cicRNA PVT1 and SMAD3 in GC cells. Decrease in SMAD3 expression suppressed CircPVT1 by releasing miR-423-5p in cells, inhibiting cell growth, invasion and migration and suppressing the EMT process.

Conclusion

CircPVT1 modulated cell growth, invasion and migration through EMT mediation in gastric cancer through miR-423-5p/Smad3 pathway.

Exosomal circ_0001190 Regulates the Progression of Gastric Cancer via miR-586/SOSTDC1 Axis

Gastric cancer (GC) is the fifth most common cancer, which has a significant impact on human health. Recent researches have shown that circular RNAs (circRNAs) could affect the progress of GC, but the mechanism still indistinct. In this work, we explored the roles of circ_0001190 in GC. The levels of circ_0001190, microRNA-586 (miR-586) and sclerostin domain containing 1 (SOSTDC1) were detected by quantitative RT-PCR and western blot in GC. The cell functions were scrutinized by cell counting kit-8 assay, 5-Ethynyl-29-deoxyuridine assay, flow cytometry assay, tube formation assay, transwell assay, and western blot. Furthermore, the relationship between miR-586 and circ_0001190 or SOSTDC1 was identified by dual-luciferase reporter assay. Finally, the xenograft model test was implemented to demonstrate the effect of exosomal circ_0001190 in vivo. The levels of circ_0001190 and SOSTDC1 were downregulated, and the miR-586 level was increased in GC. For functional assay, circ _0001190 overexpression inhibited cell vitality, cell proliferation, angiogenesis, cell migration and invasion, whereas stimulated cell apoptosis in GC cells. Circ _0001190 served as a miR-586 sponge to adjust the expression of SOSTDC1. Additionally, miR-586 could promote the advancement of GC by interfering SOSTDC1. Exosomal circ_0001190 overexpression inhibited the development of GC by miR-586/SOSTDC1 axis, which proposed a potential targeted therapy for GC cure.

Long non-coding RNA SNHG1/microRNA-195-5p/Yes-associated protein axis affects the proliferation and metastasis of gastric cancer via the Hippo signaling pathway

Long non-coding RNA (lncRNA) small nucleolar RNA host gene 1 (SNHG1) has been found to be highly expressed in gastric cancer (GC). However, the study for exploring the effects of SNHG1 and microRNA (miR)-195-5p on GC is limited. This research commits to unravel the regulatory effects of SNHG1, miRNA-195-5p, and Yes-associated protein 1 (YAP1) on GC. SNHG1, miR-195-5p and YAP1 levels in GC tissues and GC cells were detected. The GC cells were treated with various constructs altering SNHG1 or miR-195-5p expression to determine the biological activities of GC cell in vitro. The effect of SNHG1 inhibition on subcutaneous tumorigenesis of GC cells in a nude mouse model in vivo was detected. The binding relation among SNHG1, miR-195-5p, and YAP1 was validated. SNHG1 and YAP1 levels were elevated and miR-195-5p level was reduced in GC. Reduction of SNHG1 or elevation of miR-195-5p retarded GC cell biological activity in vitro. Downregulated SNHG1 suppressed tumor growth in vivo. SNHG1 bound to miR-195-5p, and miR-195-5p directly targeted YAP1. The downregulated SNHG1 hinders the biological behaviors of GC cells via the modulation of the miR-195-5p/YAP1 axis.

Raltitrexed regulates proliferation and apoptosis of HGC-27 cells by upregulating RSK4

Background

Raltitrexed is a specific inhibitor of thymidylate synthase and a potential chemotherapeutic agent for the treatment of advanced gastric cancer. In this study, we investigated the effect of raltitrexed on the proliferation of HGC-27 human gastric cancer cells and its potential underlying molecular mechanism(s).

Methods

RT-qPCR and western blotting were used to quantify RSK4 levels. Colony formation and flow cytometry assays were used to assess HGC-27 cell proliferation, cell cycle progression, mitochondrial membrane potential, and apoptosis. The expression of cell cycle and apoptosis markers were determined by western blotting.

Results

Our results demonstrate that raltitrexed upregulated RSK4 mRNA and protein levels in HGC-27 cells. Moreover, raltitrexed significantly inhibited tumor cell colony formation, arrested the cell cycle, decreased the mitochondrial membrane potential, and induced apoptosis. We observed that raltitrexed was capable of upregulating the expression of Bax, cyclin A1, and CDK3, and downregulating the expression of Bcl-2 and cleaved caspase-3. Importantly, siRNA-mediated RSK4 knockdown significantly reduced the inhibitory effect of raltitrexed on cell proliferation and its promotion of cell apoptosis. Moreover, silencing of RSK4 inhibited the raltitrexed-induced upregulation of cytochrome C. In addition, the changes in molecular markers related to the cell cycle and apoptosis induced by raltitrexed were reduced upon RSK4 depletion.

Conclusion

Our study shows that RSK4 is a key target of raltitrexed in the regulation of gastric cancer cell proliferation, cell cycle progression, and apoptosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40360-022-00605-2.

Circular RNA circ-BNC2 (hsa_circ_0008732) inhibits the progression of ovarian cancer through microRNA-223-3p/ FBXW7 axis

Background

Circular RNAs (circRNAs) are reported to be key regulators in the progression of human cancers. This work focuses on the function and molecular mechanism of circRNA-BNC2 (circ-BNC2) (also known as hsa_circ_0008732) in ovarian cancer (OC).

Methods

Quantitative real-time polymerase chain reaction (qRT-PCR) was conducted to detect circ-BNC2, microRNA-223-3p (miR-223-3p) and F-box and WD repeat domain containing 7 (FBXW7) mRNA expressions in OC tissues and cells. Besides, cell counting kit 8 (CCK-8), transwell assay and cell cycle assays were executed to assess the proliferative, migrative, invasive abilities, and cell cycle progression of OC cells, respectively. Dual-luciferase reporter gene assay and RNA pull-down assay were used to validate the targeting relationships between miR-223-3p and circ-BNC2 or FBXW7. Western blot was adopted to determine FBXW7 protein levels in OC cells.

Results

Circ-BNC2 expression was downregulated in OC tissues and cell lines, which was associated with higher FIGO stage and lymph node metastasis of OC patients. Circ-BNC2 overexpression repressed the proliferation, migration, invasion of OC cells and induced cell cycle arrest, while silencing circ-BNC2 worked oppositely. Mechanistically, circ-BNC2 could upregulate FBXW7 expression in OC cells via sponging miR-223-3p.

Conclusion

Circ-BNC2 suppresses the progression of OC via regulating miR-223-3p / FBXW7 axis. Our findings provided potential biomarker for OC therapy.

Circ_0001955 promotes the progression of non-small cell lung cancer via miR-769-5p/EGFR axis

To elaborate on the role of circular RNA 0001955 (circ_0001955) on the proliferation and apoptosis of non-small cell lung cancer (NSCLC) cells and its underlying mechanism. Circ_0001955 expression in NSCLC was screened out through bioinformatics analysis based on GEO database. Circ_0001955, microRNA-769-5p (miR-769-5p), and epidermal growth factor receptor (EGFR) expression in NSCLC tissues and cell lines was examined using quantitative real-time PCR (qRT-PCR) and Western blot. Cell proliferation and apoptosis were examined using the CCK-8 method, BrdU experiment and flow cytometry analysis, respectively. Bioinformatics prediction, dual-luciferase reporter gene experiment and RNA immunoprecipitation (RIP) experiments were applied to validate the targeting relationship between miR-769-5p and circ_0001955 and the 3' UTR of EGFR. Pearson's correlation analysis was employed to validate the correlations among them. Circ_0001955 expression was up-regulated in NSCLC tissues and cell lines, and its overexpression was strongly associated with increased tumor TNM stage and lymph node metastasis. Circ_0001955 overexpression enhanced the proliferation and restrained the apoptosis in NSCLC cells, whereas knocking down circ_0001955 exerted the opposite effects. Circ_0001955 directly targeted miR-769-5p and negatively regulated its expression. EGFR, a target gene of miR-769-5p, could be indirectly and positively regulated by circ_0001955. Correlation analysis indicated that circ_0001955 was negatively correlated with miR-769-5p expression, while circ_0001955 was positively correlated with EGFR expression. Circ_0001955 facilitates the proliferation and represses the apoptosis of NSCLC cells by modulating miR-769-5p/EGFR axis.

Effects of mir-195 Targeted Regulation of JAK2 on Proliferation, Invasion, and Apoptosis of Gastric Cancer Cells

Background. Overexpression of miR-195 can make gastric cancer cells stay in G1/G2 phase. miR-195 has been shown to inhibit gastric cancer cell replication and accelerate cell death by targeting JAK2. However, the relationship between miR-195, JAK2, and gastric cancer is not clear. Objective. To observe the effect of mir-195 regulated by JAK2 on the growth, invasion, and death of gastric cancer cells. Methods. MGC803 and NCI gastric N87 cells were introduced into the negative control sequences of miR-195 and RNA, respectively. To detect the expression of miR-195 in cells, to detect the effect of miR-195 on mitosis and proliferation of tumor cells, to analyze the effect of miR-195 on cell invasion and metastasis, and to detect the regulation of miR-195 on JAK2 expression. Results. The level of miR-195 in miR-195-MIMICS group was significantly higher than that in miR-NC group. The cell survival rate of miR-195 mimic group was lower than that of miR-NC group ( $P<0.05$ ). Compared with miR-NC group, the number of cells in G1 phase increased, the cells in G2 phase and S phase decreased, and the proportion of cells in G2 and S phase decreased in miR-195 mimic group. The scratch distance of miR-195 simulator group was larger than that of control group. The number of invasive cells in the miR-195 mimic group was significantly lower than that in the control group. The expression of JAK2 protein in miR-195 mimic group was lower than that in miR-NC group. There was a significant negative correlation between the expression level of miR-195 and JAK2 (rhabdomile 0.326 and record 0.00). There are continuous interaction fragments between JAK2 and miR-195. The luciferase activity of miR-195 mimic and wild type JAK2 sequence expression vector was significantly lower than that of wild type JAK2 sequence expression vector. Conclusion. miR-195 may inhibit the occurrence, metastasis, and invasion of gastric tumor by downregulating the expression of JAK2. miR-195/JAK2 may be a new molecular target for the treatment of gastrointestinal tumors.

Circ_0005918 Sponges miR-622 to Aggravate Intervertebral Disc Degeneration

Intervertebral discdegeneration (IDD) is the most common cause of lower back pain, but the exact molecular mechanism of IDD is still unknown. Recently, studies have shown that circular RNAs (circRNAs) regulate diverse biological procedures such as cell metastasis, growth, metabolism, migration, apoptosis, and invasion. We demonstrated that IL-1β and TNF-α induced circ_0005918 expression in the NP cell, and circ_0005918 was overexpressed in the IDD group compared with the control group. Moreover, the upregulated expression of circ_0005918 was associated with disc degeneration degree. The elevated expression of circ_0005918 promoted cell growth and ECM degradation, and it induced secretion of inflammatory cytokines including IL-1β, IL-6, and TNF-α. Moreover, we found that circ_0005918 sponged miR-622 in the NP cell. In addition, the exposure to IL-1β and TNF-α suppressed the expression of miR-622, which was downregulated in the IDD group compared with the control group. Furthermore, the downregulated expression of miR-622 was associated with disc degeneration degree. The expression level of miR-622 was negatively associated with circ_0005918 expression in the IDD group. In conclusion, circ_0005918 regulated cell growth, ECM degradation, and secretion of inflammatory cytokines by regulating miR-622 expression. These data suggested that circ_0005918 played important roles in the development of IDD via sponging miR-622.

Circular RNA circ_0005835 promotes promoted neural stem cells proliferation and differentiate to neuron and inhibits inflammatory cytokines levels through miR-576-3p in Alzheimer's disease

Alzheimer's disease (AD) is the most frequent neurodegenerative disease and it is difficult to have an effective and simple method for AD early diagnosis. CircRNAs (circular RNAs) are novel discovered non-coding endogenous RNAs that affect cell apoptosis, differentiation, growth, metabolism, and metastasis. Recently, it has reported that circ_0005835 was one upregulated circRNA in the AD patients. However, the function role of circ_0005835 remains unknown. In our study, we found that circ_0005835 was upregulated in AD patients and cell models. Knockdown of circ_0005835 could downregulate neuroinflammation in BV2 cells. Moreover, knockdown of circ_0005835 promoted neural stem cells (NSC) proliferation and differentiate to neuron. These data mean that circ_0005835 plays important role in the development of AD. The miR-576-3p expression in serum was downregulated in the AD group compared to the health control group. Consistently, the level of circ_0005835 was overexpressed in the Aβ-treated in both SH-SY5Y and BV2 cells. Moreover, the expression of miR-576-3p was negatively correlated with circ_0005835 in AD patients. In addition, we performed the rescued experiments to show that knockdown of circ_0005835 could downregulate neuroinflammation through sponging miR-576-3p in BV2 cells. Inhibition of circ_0005835 promoted NSC proliferation and differentiate to neuron via sponging miR-576-3p. These data suggested that circ_0005835 promoted AD development through regulating miR-576-3p expression.

Homogenous multifunctional microspheres induce ferroptosis to promote the anti-hepatocarcinoma effect of chemoembolization

Transcatheter arterial chemoembolization (TACE) is one of the main palliative therapies for advanced hepatocellular carcinoma (HCC), which is also regarded as a promising therapeutic strategy for cancer treatment. However, drug-loaded microspheres (DLMs), as commonly used clinical chemoembolization drugs, still have the problems of uneven particle size and unstable therapeutic efficacy. Herein, gelatin was used as the wall material of the microspheres, and homogenous gelatin microspheres co-loaded with adriamycin and Fe₃O₄ nanoparticles (ADM/Fe₃O₄-MS) were further prepared by a high-voltage electrospray technology. The introduction of Fe₃O₄ nanoparticles into DLMs not only provided excellent T2-weighted magnetic resonance imaging (MRI) properties, but also improved the anti-tumor effectiveness under microwave-induced hyperthermia. The results showed that ADM/Fe₃O₄-MS plus microwave irradiation had significantly better antitumor efficacy than the other types of microspheres at both cell and animal levels. Our study further confirmed that ferroptosis was involved in the anti-tumor process of ADM/Fe₃O₄-MS plus microwave irradiation, and ferroptosis marker GPX4 was significantly decreased and ACSL4 was significantly increased, and ferroptosis inhibitors could reverse the tumor cell killing effect caused by ADM/Fe₃O₄-MS to a certain extent. Our results confirmed that microwave mediated hyperthermia could amplify the antitumor efficacy of ADM/Fe₃O₄-MS by activating ferroptosis and the introduction of Fe₃O₄ nanoparticles can significantly improve TACE for HCC. This study confirmed that it was feasible to use uniform-sized gelatin microspheres co-loaded with Fe₃O₄ nanoparticles and adriamycin to enhance the efficacy of TACE for HCC.

Hsa_circ_0134111 promotes intervertebral disc degeneration via sponging miR-578

Intervertebral disc degeneration (IDD) is a chronic degenerative and age-dependent process characterized by aberrant apoptosis, proliferation, synthesis, and catabolism of the extracellular matrix of the nucleus pulposus (NP) cells. Recently, studies showed that circular RNAs play important roles in the development of many diseases. However, the role of circRNAs in IDD development remains unknown. We showed that circ_0134111 level was overexpressed in IDD tissue samples as compar-ed to control tissues. The upregulation of circ_0134111 was more drastic in the moderate and severe IDD cases than in those with mild IDD. In addition, we showed that interleukin-1β and tumor necrosis factor-α exposure significantly enhanced circ_0134111 expression in NP cells. Furthermore, ectopic expression of circ_0134111 induced proliferation, pro-inflammatory cytokine secretion, and ECM degradation in the NP cells. We also showed that circ_0134111 directly interacted with microRNA (miR)-578 in NP cells where elevated expression of circ_0134111 enhanced the ADAMTS-5 and MMP-9 expression. Moreover, miR-578 expression was significantly decreased in IDD patients and the miR-578 expression was negatively correlated with circ_0134111 expression in the IDD samples. Interleukin-1β and tumor necrosis factor-α exposure significantly decreased miR-578 levels in NP cells, in which ectopic miR-578 expression inhibited cell growth, pro-inflammatory cytokine expression, and ECM degradation. Finally, we showed that circ_0134111 overexpression induced the IDD-related phenotypic changes through inhibiting miR-578. These data suggested that circ_0134111 could promote the progression of IDD through enhancing aberrant NP cell growth, inflammation, and ECM degradation partly via regulating miR-578.

Circular RNAs in Intervertebral Disc Degeneration: An Updated Review

Low back pain, a common medical condition, could result in severe disability and inflict huge economical and public health burden. Its pathogenesis is attributed to multiple etiological factors, including intervertebral disc degeneration (IDD). Emerging evidence suggests that circular RNAs (circRNAs), a major type of regulatory non-coding RNA, play critical roles in cellular processes that are pertinent to IDD development, including nucleus pulposus cell proliferation and apoptosis as well as extracellular matrix deposition. Increasing number of translational studies also indicated that circRNAs could serve as novel biomarkers for the diagnosis of IDD and/or predicting its clinical outcomes. Our review aims to discuss the recent progress in the functions and mechanisms of newly discovered IDD-related circRNAs.

Circular RNA circ_0000423 promotes gastric cancer cell proliferation, migration and invasion via the microR-582-3p/Disheveled-Axin domain containing 1 axis

For humans, gastric cancer (GC) is a common malignancy. Multiple circular RNAs (circRNAs) have been confirmed to be important cancer-promoting or tumor-suppressive factors. The present study discusses the roles and mechanisms of circ_0000423 in GC development. In this study, circ_0000423 expression in GC patient tissue samples and cell lines was detected via quantitative real-time polymerase chain reaction. Disheveled-Axin domain containing 1 (DIXDC1) expression in GC cells was examined via Western blot. Besides, cell counting kit-8 was utilized for detecting GC cell viability. GC cell migration and invasion were examined through Transwell assays. Bioinformatics and dual-luciferase reporter gene assays were employed to verify the regulatory relationships between microRNA-582-3p (miR-582-3p) and circ_0000423 or DIXDC1. In the present study, we demonstrated that circ_0000423 was highly expressed in GC. Circ_0000423 knockdown suppressed GC cell viability, migration and invasion. Moreover, miR-582-3p was confirmed as a direct target of circ_0000423, and an upstream regulator of DIXDC1. MiR-582-3p inhibition or DIXDC1 overexpression could reverse the above-mentioned effects of knocking down circ_0000423 on GC cells. In conclusion, circ_0000423 facilitates GC progression by modulating the miR-582-3p/DIXDC1 axis.

circPTEN suppresses colorectal cancer progression through regulating PTEN/AKT pathway

Recently, circular RNAs (circRNAs) have attracted growing attention due to their pivotal roles in the complicated cellular processes of diverse human malignancies, including colorectal cancer (CRC). Phosphatase and tensin homolog (PTEN) is known as a typical tumor-suppressing gene. Nevertheless, limited investigation on the function of circRNAs generated from PTEN has been undertaken. In this research, hsa_circ_0094343 (circPTEN) was found to display low expression in CRC tissues and cells. CircPTEN is characterized with high stability due to its circular structure. Upregulation of circPTEN suppressed CRC cell proliferation, migration, and invasion but facilitated apoptosis. Data from mechanism assays revealed that circPTEN could elevate PTEN expression through sequestering microRNA-4470 (miR-4470) in CRC cells. Further, circPTEN was validated to inhibit K63-linked ubiquitination of protein kinase B (AKT) and AKT phosphorylation at Thr-308 and Ser-473 by competitively binding with tumor necrosis factor (TNF)-receptor-associated factor 6 (TRAF6). Moreover, the results of rescue assays indicated that the suppressive effect of circPTEN on CRC progression could be totally reversed by overexpression of insulin like growth factor 1 (IGF-1) or partially reversed by knockdown of PTEN. To conclude, circPTEN suppresses CRC progression via regulation of PTEN/AKT pathway.

LncRNA UCA1, miR-26a, and miR-195 in coronary heart disease patients: Correlation with stenosis degree, cholesterol levels, inflammatory cytokines, and cell adhesion molecules

Background

Long noncoding RNA urothelial cancer‐associated 1 (lnc‐UCA1) targets microRNA‐26a (miR‐26a) and microRNA‐195 (miR‐195) to participate in coronary heart disease (CHD) progression via regulation of vascular smooth muscle cell and microvascular endothelial cell viability and mobility. Therefore, this study set out to further explore the relationship between lnc‐UCA1 and miR‐26a and miR‐195, along with their roles in the management of patients with CHD.

Methods

One hundred and thirty‐six CHD patients and 70 age‐/gender‐matched controls were recruited in this case‐control study. Their peripheral blood mononuclear cell samples were collected for lnc‐UCA1, miR‐26a, and miR‐195 measurement. Furthermore, serum samples from CHD patients were obtained for inflammatory cytokines and cell adhesion molecules measurement. The Gensini score was used to evaluate the stenosis severity in CHD patients.

Results

Lnc‐UCA1 expression tend to be increased, while miR‐26a and miR‐195 expressions were reduced in patients with CHD compared to that of controls (all p < 0.001). In CHD patients, lnc‐UCA1 was negatively correlated with miR‐26a (p < 0.001) and miR‐195 (p = 0.014). Besides, lnc‐UCA1 was positively correlated with Gensini score (p < 0.001), total cholesterol (p = 0.019), low‐density lipoprotein cholesterol (p = 0.002), and C‐reactive protein (p < 0.001), while miR‐26a (p < 0.001) and miR‐195 (p = 0.002) were negatively correlated with Gensini score. What's more, lnc‐UCA1 was positively correlated with tumor necrosis factor (TNF)‐α (p = 0.004), interleukin (IL)‐1β (p = 0.041), vascular cell adhesion molecule‐1 (VCAM‐1) (p = 0.010), and intercellular adhesion molecule‐1 (ICAM‐1) (p < 0.001). While miR‐26a was negatively correlated with some of the individual inflammatory cytokines and cell adhesion molecules.

Conclusion

Lnc‐UCA1, miR‐26a, and miR‐195 may serve as potential biomarkers for CHD management.

Contribution of circRNAs in gastric cancer

Gastric cancer (GC) is one of the most commonly diagnosed neoplasms in the world. A number of environmental and lifestyle factors, particularly chronic infection with Helicobacter pylori, have been found to partake in the pathogenesis of GC. The advent of high-throughput genome and transcriptome analysis has enhanced the knowledge about molecular mechanisms of the pathogenesis of GC. However, data regarding the expression of several circRNAs, such as circLMTK2, are not consistent. We explain the role of circRNAs in the development of GC. We searched databases for the newest publications using the terms gastric cancer and circRNA. Each circRNA alteration, downstream targets, its impacts on cancer cells, and the prognostic and diagnostic roles of these circRNAs have been discussed. Taken together, circRNAs can be putative biomarkers in GC and potential targets for the treatment of this cancer. Yet, this field is still in its infancy and needs further experiments for reaching the clinical application. As these transcripts are stable in circulation, they can be used in non-invasive methods of cancer detection and patients' follow-up.

Emerging roles of circular RNAs in neuropathic pain

Neuropathic pain is a major type of chronic pain caused by the disease or injury of the somatosensory nervous system. It afflicts about 10% of the general population with a significant proportion of patients’ refractory to conventional medical treatment. This highlights the importance of a better understanding of the molecular pathogenesis of neuropathic pain so as to drive the development of novel mechanism‐driven therapy. Circular RNAs (circRNAs) are a type of non‐coding, regulatory RNAs that exhibit tissue‐ and disease‐specific expression. An increasing number of studies reported that circRNAs may play pivotal roles in the development of neuropathic pain. In this review, we first summarize circRNA expression profiling studies on neuropathic pain. We also highlight the molecular mechanisms of specific circRNAs (circHIPK3, circAnks1a, ciRS‐7, cZRANB1, circZNF609 and circ_0005075) that play key functional roles in the pathogenesis of neuropathic pain and discuss their potential diagnostic, prognostic, and therapeutic utilization in the clinical management of neuropathic pain.

LncRNA DARS-AS1 aggravates the growth and metastasis of hepatocellular carcinoma via regulating the miR-3200-5p-Cytoskeleton associated protein 2 (CKAP2) axis

Accumulating signs have found that long noncoding RNAs (lncRNAs) contribute to hepatocellular carcinoma (HCC). Here, we probed the effect and mechanism of lncRNA DARS-AS1 in HCC. The profiles of DARS-AS1 and Cytoskeleton associated protein 2 (CKAP2) in 50 HCC tissues and non-tumor tissues were examined by real-time quantitative polymerase chain reaction (RT-qPCR). DARS-AS1 and CKAP2 overexpression and/or knockdown cell models were established. The proliferation, apoptosis, invasion and epithelial-mesenchymal transition (EMT) were determined. CKAP2, and focal adhesion kinase (FAK)-extracellular signal-regulated kinase (ERK) was tested by Western blot (WB). The relationship between DARS-AS1 and CKAP2 was predicted by Bioinformatics, and the dual-luciferase reporter assay was applied to verify the targeting association between miR-3200-5p and DARS-AS1 and CKAP2. DARS-AS1 was overexpressed in HCC tissues (vs. that in non-tumor tissues) and was closely correlated with the patients’ tumor stage. DARS-AS1 facilitated HCC cell proliferation and hampered apoptosis. HCC cell migration and EMT were enhanced by DARS-AS1. DARS-AS1 up-regulated CKAP2, which aggravated HCC. Further investigation illustrated that either DARS-AS1 or CKAP2 activated FAK-ERK pathway, and miR-3200-5p was competitively restrained by DARS-AS1. miR-3200-5p exerted tumor-suppressive effects in HCC and inactivated CKAP2 and FAK-ERK pathway. All in all, this study corroborates that DARS-AS1 facilitates HCC proliferation and metastasis by regulating miR-3200-5p-mediated CKAP2, which provides a potential target for HCC diagnosis and treatment.

Abbreviations: CCK-8: cell counting kit-8; CKAP2: Cytoskeleton associated protein 2; cDNA:complementary DNA; DAPI: 4ʹ,6-diamidino-2-phenylindole; DARS-AS1: DARS1 antisense RNA 1; DEPC: diethyl pyrocarbonate; DMEM-F12: Dulbecco’s minimal essential medium/Ham’s-F12; EMT: epithelial-mesenchymal transition; ERK: extracellular signal-regulated kinase; FAK: focal adhesion kinase; FBS: fetal bovine serum; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; HCC: hepatocellular carcinoma; HE: hematoxylin-eosin; IHC: Immunohistochemistry; LIHC: Liver hepatocellular carcinoma; lncRNAs: long noncoding RNAs; MIAT: lncRNA myocardial infarction-related transcripts; MT: Mutant; NC: negative control; PBS: phosphate-buffered saline; PMSF: Phenylmethylsulfonyl fluoride; PVDF: polyvinylidene difluoride; RT: room temperature; RT-qPCR: real-time quantitative polymerase chain reaction; SDS-PAGE: sodium dodecyl sulfate-polyacrylamide gel electrophoresis; SPF: specific pathogen-free; TMAP: tumor-associated microtubule-associated protein; TUNEL: TdT-mediated dUTP nick end labeling; V: volume; WT: wild type.

Circ_0007534 Silencing Inhibits the Proliferation, Migration and Invasion and Induces the Apoptosis of Glioma Cells Partly Through Down-Regulating PROX1 Via Elevating miR-22-3p Level

Glioma is a common malignant brain neoplasm. The role and mechanism of circular RNA 0,007,534 (circ_0007534) in glioma progression were investigated in this study. The expression of circ_0007534, microRNA-22-3p (miR-22-3p) and prospero homeobox protein 1 (PROX1) messenger RNA (mRNA) was determined by quantitative real-time polymerase chain reaction (qRT-PCR). The proliferation, migration and invasion abilities were analyzed by colony formation assay, transwell migration assay and transwell invasion assay. Cell apoptosis was assessed through measuring the activity of Caspase-3 using the Caspase-3 kit and the apoptosis rate using flow cytometry. Dual-luciferase reporter assay was used to confirm the target interaction between miR-22-3p and circ_0007534 or PROX1. The protein level of PROX1 was examined by Western blot assay. Animal studies were conducted to analyze the influence of circ_0007534 interference on xenograft tumor growth in vivo. Circ_0007534 was highly expressed in glioma tissues and cell lines relative to that in normal tissues and NHA cell line. Circ_0007534 knockdown suppressed the proliferation and motility while induced the apoptosis of glioma cells. Circ_0007534 negatively regulated miR-22-3p level through targeting it in glioma cells. Circ_0007534 interference-induced influences in glioma cells were partly overturned by the silencing of miR-22-3p. PROX1 was a target of miR-22-3p, and circ_0007534 interference-mediated effects in glioma cells were largely diminished by the overexpression of PROX1. Circ_0007534 interference restrained glioma development in vivo. Circ_0007534 aggravated glioma progression through elevating PROX1 expression via targeting miR-22-3p, which provided new targets for the diagnosis and treatment of glioma.

Emerging roles of circular RNAs in osteoporosis

Osteoporosis is one bone disease characterized with skeletal impairment, bone strength reduced and fracture risk enhanced. The regulation processes of bone metabolism are associated with several factors such as mechanical stimulation, epigenetic regulation and hormones. However, the mechanism of osteoporosis remains unsatisfactory. Increasing high‐throughput RNA sequencing and circular RNAs (circRNAs) microarray studies indicated that circRNAs are differentially expressed in osteoporosis. Growing functional studies further pinpointed specific deregulated expressed circRNAs (e.g., circ_28313, circ_0016624, circ_0006393, circ_0076906 and circ_0048211) for their functions involved in bone metabolism, including bone marrow stromal cells (BMSCs) differentiation, proliferation and apoptosis. Moreover, CircRNAs (circ_0002060, Circ_0001275 and Circ_0001445) may be acted as diagnostic biomarkers for osteoporosis. This review discussed recent progresses in the circRNAs expression profiling analyses and their potential functions in regulating BMSCs differentiation, proliferation and apoptosis.

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.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-021-02373-5.

Vinclozolin-induced mouse penile malformation and "small testis" via miR132, miR195a together with the Hippo signaling pathway

Vinclozolin (VCZ) is a fungicide with antiandrogen activity. Exposure to VCZ in maternal uterus may cause uterine, ovarian and testicular damage, hypospadias and prostate abnormality in the offspring. Hippo pathway, which is highly conservative and may be activated by miR132 and miR195a, can control organ size and tissue regeneration, and participate in injury and deformity. In the present study, VCZ was found to have caused penile malformation in the male offspring and also induced "small testis" when it was administered to the pregnant mice orally at a dose of 400 mg kg^-1 day^-1 on Days 12-18 of gestation. At 1, 3 and 7 weeks of age, VCZ could increase miR132, Mst1, Sav1, phosphorylated Yes-associated protein (pYap) and pLats, and decrease Yap in offspring penises and testes. Besides, it could also raise miR195a both in the testes of 1, 7-week and in the penises of all the three ages. In addition, we found the levels of some cyclin (Ccn) genes elevated in the testes, the expression of the androgen receptor (Ar) gene dereased and Jnks changed in the penises of offspring aged 1, 3 and 7 weeks. The results suggest that that gestational VCZ exposure could not only increase miR132 and miR195a in penises and testes of the offspring, but also activate Hippo pathway and down-regulate Ar. These may directly inhibit cell proliferation, accelerate cell death by up-regulating the expression of some Ccns, and ultimately lead to penile and testicular damage and malformations in the offspring.

Circular RNA hsa_circ_0110389 promotes gastric cancer progression through upregulating SORT1 via sponging miR-127-5p and miR-136-5p

Increasing studies have found that circular RNAs (circRNAs) are aberrantly expressed and play important roles in the occurrence and development of human cancers. However, the function of circRNAs on environmental carcinogen-induced gastric cancer (GC) progression remains poorly elucidated. In the present study, hsa_circ_0110389 was identified as a novel upregulated circRNA in malignant-transformed GC cells through RNA-seq, and subsequent quantitative real-time PCR verified that hsa_circ_0110389 was significantly increased in GC tissues and cells. High hsa_circ_0110389 expression associates with advanced stages of GC and predicts poor prognosis. Knockdown and overexpression assays demonstrated that hsa_circ_0110389 regulates proliferation, migration, and invasion of GC cells in vitro. In addition, hsa_circ_0110389 was identified to sponge both miR-127-5p and miR-136-5p and SORT1 was validated as a direct target of miR-127-5p and miR-136-5p through multiple mechanism assays; moreover, hsa_circ_0110389 sponged miR-127-5p/miR-136-5p to upregulate SORT1 expression and hsa_circ_0110389 promoted GC progression through the miR-127-5p/miR-136-5p-SORT1 pathway. Finally, hsa_circ_0110389 knockdown suppressed GC growth in vivo. Taken together, our findings firstly identify the role of hsa_circ_0110389 in GC progression, which is through miR-127-5p/miR-136-5p-SORT1 pathway, and our study provides novel insight for the identification of diagnostic/prognostic biomarkers and therapeutic targets for GC.

Circular RNA circAFF2 accelerates gastric cancer development by activating miR-6894-5p and regulating ANTXR 1 expression

BACKGROUND

Circular RNAs (circRNAs) contain a new class of non-coding RNAs that play an important role in adjusting biological function and gene expression. But the function of circRNAs in gastric cancer remains unclear. In the present research, we explored the functions of circular RNA AFF2(circAFF2, hsa_circ_0001947) in gastric cancer cells and an animal model of gastric cancer.

METHODS

The expression of circAFF2, microRNA-6894-5p (miR-6894-5p), and Anthrax toxin receptor 1 (ANTXR 1) were determined by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Cell counting kit 8 (CCK-8) and transwell assays were used to analyze the knockdown effects of circAFF2, miR-6894-5p, and overexpression of ANTXR 1 on cell proliferation, migration, and invasion abilities. Binding interactions between, circAFF2 and miR-6894-5p and between, miR-6894-5p and ANTXR 1 were detected by Dual-luciferase reporter assays. Levels of protein expression were analyzed by Western blotting. Tumor models were established by subcutaneous injection of tumor cells in nude mice.

RESULT

The result showed that circAFF2 expression was significantly increased in gastric cancer cell lines and tissues. The knockdown of circAFF2 dramatically suppressed the cell migration, invasion and proliferation of gastric cancer cells. In vivo studies showed that knockdown of circAFF2 delayed tumor growth. Furthermore, we revealed that circAFF2 functioned as a sponge to absorb miR-6984-5p and elevated the expression of ANTXR 1.

CONCLUSION

CircAFF2 acts as an oncogene in gastric cancer and exerts its effects via miR-6894-5p/ANTXR 1 signaling.

Hsa_circ_0032463 acts as the tumor promoter in osteosarcoma by regulating the miR‑330‑3p/PNN axis

Osteosarcoma (OS), also known as bone cancer, is a threat to the lives of millions of adolescents worldwide. Although dedicated efforts have been invested in reducing the mortality rate of this bone cancer, the research community is yet to find the exact causes of OS. Thus, the present research aimed to study the association between circular RNA circ_0032463 and OS progression. The impact of circ_0032463 on cells with OS was first evaluated using reverse transcription-quantitative PCR. This evaluation was followed by the assessment of cell proliferation, viability, apoptosis, invasion and adhesion using BrdU, Cell Counting Kit-8, flow cytometry, Transwell and cell adhesion assays, respectively. RNA pull-down, RNA immunoprecipitation chip and dual-luciferase reporter systems were utilized to investigate the relationship between circ_0032463, microRNA (miR)-330-3p and Pinin desmosome associated protein (PNN) in OS. The findings indicated that circ_0032463 and PNN were highly expressed in OS tissues and OS cell lines, and that they facilitated cell proliferation, viability, invasion and adhesion, but attenuated cell apoptosis in OS cells. The low expression of miR-330-3p suppressed OS development. It was also noted that circ_0032463 inhibited miR-330-3p to upregulate PNN expression. In conclusion, this study confirmed that by regulating the miR-330-3p/PNN axis, circular RNA circ_0032463 could function as a tumor enhancer in cells with OS.

Circ_0000144 functions as a miR-623 sponge to enhance gastric cancer progression via up-regulating GPRC5A

BACKGROUND

Gastric cancer (GC) remains one of the most common malignancies worldwide. Increasing evidence has demonstrated that circRNAs serve as critical roles in human cancer, including GC. In the present study, we focused on the detailed function and mechanism of circ_0000144 on GC progression.

METHODS

The levels of circ_0000144, miR-623 and G-protein-coupled receptor, family C, group 5, member A (GPRC5A) were determined by quantitative real-time polymerase chain reaction (qRT-PCR). Targeted relationships among circ_0000144, miR-623 and GPRC5A were confirmed using dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. Cell proliferation, colony formation, apoptosis, migration and invasion were evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), colony formation, flow cytometry and transwell assays. Measurement of glutamine and α-ketoglutarate (α-KG) levels was performed using a corresponding assay kit. GPRC5A protein expression was detected using Western blot. In vivo assays were used to explore the impact of circ_0000144 on tumor growth.

RESULTS

Our data indicated that circ_0000144 was up-regulated and miR-623 was down-regulated in GC tissues and cells. Circ_0000144 interacted with miR-623 through directly binding to miR-623. Moreover, the knockdown of circ_0000144 weakened GC cell proliferation, colony formation, migration, invasion and glutaminolysis and accelerated cell apoptosis by up-regulating miR-623. GPRC5A was a direct target of miR-623 and circ_0000144 protected against GPRC5A repression through sponging miR-623. Furthermore, miR-623-mediated regulation on GC cell progression was reversed by the stored expression of GPRC5A. Additionally, circ_0000144 depletion inhibited tumor growth in vivo.

CONCLUSION

Our study indicated that circ-0000144 knockdown repressed GC progression at least partly by regulating GPRC5A expression via sponging miR-623, illumining a novel therapeutic target for GC treatment.

MicroRNA-1249 Targets G Protein Subunit Alpha 11 and Facilitates Gastric Cancer Cell Proliferation, Motility and Represses Cell Apoptosis

Aim

The purpose of our study was to investigate the effects of miR-1249 in gastric cancer.

Methods

By analyzing the data obtained from TCGA database, the expression and prognosis of miR-1249 in gastric cancer patients were analyzed. Then, CCK8, colony forming and transwell assays were used to test cell proliferation and motility. The cell apoptosis was detected by flow cytometry. The Pearson correlation coefficient analyzed was applied to analyze the correlation between GNA11 and miR-1249. qRT-PCR and Western blotting assays were employed to detect the mRNA and protein levels.

Results

We discovered that miR-1249 was highly expressed and was associated with a worse prognosis in gastric cancer patients. Besides, miR-1249 was up-regulated in gastric cancer cell lines (AGS, MKN45 and SNU1). More interestingly, miR-1249 exerted facilitating impacts on gastric cancer cell proliferation and motility, whereas miR-1249 acted as a suppressing effect on gastric cancer apoptosis. G protein subunit alpha 11 (GNA11) was a target gene of miR-1249 and was negatively correlated with miR-1249. Furthermore, GNA11 was negatively regulated by miR-1249. Additionally, GNA11 was lowly expressed in gastric cancer tissues and cell lines, as well as low GNA11 expression, was related to poor overall survival results in gastric cancer patients. The promoting influences of miR-1249 over-expression on AGS cell proliferation and motility was rescued by GNA11 over-expression, which might be achieved by regulating PI3K/AKT/mTOR signalling pathway.

Conclusion

Above all, we concluded that miR-1249 was concerned with the progression of gastric cancer through regulating GNA11, suggesting that miR-1249 and GNA11 might serve as predictive biomarkers for gastric cancer therapy.

Circ_0000527 promotes osteosarcoma cell progression through modulating miR-646/ARL2 axis

Accumulating evidence shows that circRNAs play critical roles in the development of human tumors. We observed that circ_0000527 was overexpressed in osteosarcoma cells (SAOS-2, HOS, MG-63 and U2OS) compared in hFOB1.19 cells. We demonstrated that the circ_0000527 level was higher in osteosarcoma specimens than in non-tumor specimens. The ectopic expression of circ_0000527 was shown to induce cell growth, cell cycle progression and the secretion of inflammatory mediators, including IL-1β, IL-6, IL-8 and TNF-α. We demonstrated that circ_0000527 sponges miR-646 in osteosarcoma cells and that ARL2 is a target gene of miR-646. MiR-646 expression was decreased and ARL2 was overexpressed in osteosarcoma cells (SAOS-2, HOS, MG-63 and U2OS) compared to hFOB1.19 cells. Overexpression of circ_0000527 was demonstrated to induce ARL2 expression in MG-63 cells. We showed that miR-646 was downregulated in osteosarcoma specimens compared to that of non-tumor specimens and that the level of circ_0000527 was negatively correlated with miR-646 expression in osteosarcoma specimens. The elevated expression of circ_0000527 was shown to promote cell growth and cell cycle progression by modulating miR-646 expression. The ectopic expression of circ_0000527 was shown to promote cell growth, cell cycle progression and the secretion of inflammatory mediators by modulating ARL2. The present study suggested that the circ_0000527/miR-646/ARL2 axis may be a potential treatment target for osteosarcoma.

CircAgtpbp1 Acts as a Molecular Sponge of miR-543-5p to Regulate the Secretion of GH in Rat Pituitary Cells

CircRNAs have been identified to be expressed differently and stably in numerous species and tissues, but their functions in growth hormone (GH) secretion are still largely unknown. In summary, we have revealed a circRNA-miRNA-mRNA network that may play a biological role in the rat pituitary gland. First, we verified the chromosome location information of circAgtpbp1 according to sequencing analysis. The circAgtpbp1 characteristics were authenticated through PCR, qRT-PCR, treating with RNase and fluorescent in situ hybridization (FISH). Second, we detected the expression pattern of circAgtpbp1 in the rat anterior pituitary by qRT-PCR. We also designed circAgtpbp1 siRNA and constructed overexpression plasmid to evaluate the effect of circAgtpbp1 function on GH secretion by qRT-PCR, ELISA and Western blot. CircAgtpbp1 is a stable, truly circular molecule. We found that circAgtpbp1 interacted with miR-543-5p and can regulate GH secretion in pituitary cells through a circAgtpbp1-miR-543-5p-GH axis. Overall, the evidence generated by our study suggests that circAgtpbp1 can act as a sponge of miR-543-5p to reduce the inhibitory effect of miR-543-5p on Gh1 and further promote GH secretion. These findings expand our existing knowledge on the mechanisms of hormone regulation in the pituitary gland.

Circ-UBAP2 functions as sponges of miR-1205 and miR-382 to promote glioma progression by modulating STC1 expression

Background

Circular RNAs (circRNAs) exert vital functions in glioma pathogenesis. CircRNA ubiquitin‐associated protein 2 (circ‐UBAP2, hsa_circ_0008344) has been illuminated as a tumor driver in glioma. Nevertheless, the mechanisms underlying the oncogenic regulation of circ‐UBAP2 in glioma are still undefined.

Methods

Circ‐UBAP2, miR‐1205, miR‐382, and GPRC5A were quantified using qRT‐PCR and western blot. Cell viability was detected using a CCK‐8 assay. Cell migration and invasion were measured using the would‐healing and transwell assays. Flow cytometry and colony formation assay were applied to evaluate cell apoptosis and colony formation, respectively. The xenograft model assays were used to examine the impact of circ‐UBAP2 on tumorigenic effect in vivo. Direct relationships among circ‐UBAP2, miR‐1205, miR‐382, and GPRC5A were confirmed using dual‐luciferase reporter assays.

Results

Circ‐UBAP2 expression was upregulated in glioma. The reduced level of circ‐UBAP2 hampered cell proliferation, migration, invasion, and enhanced apoptosis in vitro and weakened tumor growth in vivo. Mechanistically, circ‐UBAP2 directly bound to miR‐1205 and miR‐382. miR‐1205 and miR‐382 mediated the regulation of circ‐UBAP2 silencing on glioma cell behaviors. Moreover, GPRC5A was a functional target of miR‐1205 and miR‐382 in regulating glioma cell behaviors. Furthermore, circ‐UBAP2 mediated GPRC5A expression through miR‐1205 or miR‐382 in glioma cells.

Conclusion

Our current findings identified that circ‐UBAP2 silencing impeded glioma malignant progression partially by downregulating GPRC5A through targeting miR‐1205 and miR‐382.

GPRC5A: An emerging prognostic biomarker for predicting malignancy of Pancreatic Cancer based on bioinformatics analysis

Background: Pancreatic cancer (PaCa) is a highly lethal malignancy. The treatment options for PaCa lack efficacy. The study aimed to explore the molecular biomarkers for predicting survival of PaCa and identify the potential carcinogenic mechanisms of the selected gene.

Methods: Based on public databases of PaCa, differentially expressed genes (DEGs) were identified using Networkanalyst. Survival analyses were exerted on GEPIA. Oncomine and The Human Protein Atlas were used for verifying the expression on mRNA and protein levels. Enrichment analyses were generated on Metascape and gene set enrichment analysis (GSEA). Univariate analyses were performed to determine the clinical factors associated with the expression of GPRC5A.

Results: GPRC5A was identified as the most valuable gene in predicting survival of PaCa patients. Patients with high expression of GPRC5A showed larger tumor size, higher TNM stages, higher tumor grade, and more positive resection margin. In mutant KRAS, TP53, CDKN2A and SMAD4 group, the expression of GPRC5A was higher than non-mutant group. Mechanistically, GPRC5A may promote metastasis of PaCa mainly via regulating epithelial-mesenchymal transition (EMT) and neuroactive ligand-receptor interaction.

Conclusion: GPRC5A may act as an oncogene in the progression of PaCa and could be a prognostic biomarker in predicting survival of PaCa.

Circ_SMAD4 promotes gastric carcinogenesis by activating wnt/β-catenin pathway

Objectives

Circular RNAs (circRNAs) are essential participants in tumour progression. This study focused on investigating the mechanism of a novel functional circRNA in gastric cancer (GC).

Methods

Gene expression was detected by qRT‐PCR or Western blot. Survival curves were generated via Kaplan‐Meier method. In vitro and in vivo assays were used to investigate the impact of circ_SMAD4 on GC cell growth and tumorigenesis. Agarose gel electrophoresis assay, RNase R treatment and Sanger sequencing were utilized for confirming the circular structure of circ_SMAD4. Relationship between molecules was monitored by a series of mechanical experiments, as needed.

Results

Circ_SMAD4 expression was potentiated in GC. Circ_SMAD4 depletion impeded GC cell growth in vitro and restrained tumorigenesis in vivo. Mechanically, nuclear circ_SMAD4 recruited TCF4 to facilitate CTNNB1 transcription, while cytoplasmic circ_SMAD4 sequestered miR‐1276 to prevent the silence of CTNNB1 mRNA, leading to activation of Wnt/β‐catenin pathway. Rescue experiments validated that circ_SMAD4 depended on miR‐1276/TCF4‐regulated CTNNB1 to elicit accelerating effects on GC cell growth.

Conclusion

Circ_SMAD4 facilitated GC tumorigenesis by activating CTNNB1‐dependent Wnt/β‐catenin pathway. Hopefully, the findings could provide new clues for improving GC prognosis and treatment.

MiR-548d-3p Promotes Gastric Cancer by Targeting RSK4

Purpose

Previous studies have demonstrated that RSK4 inhibits the proliferation of gastric cancer cells and the occurrence of tumors. However, to date, studies involving microRNAs (miRNAs) that target RSK4 have rarely been reported. Thus, this study aimed to investigate the miRNAs that target RSK4.

Materials and Methods

We screened miRNAs related to RSK4 in miRDB, microT-CDS, TargetScan, and mirDIP databases and found 18 miRNAs. We chose miR-548d-3p for follow-up research, identified the interaction site in RSK4 by comparing the sequence, and mutated it. Thereafter, we used the dual-luciferase reporter system, real-time PCR (RT-PCR), and Western blotting to assess the effect of miR-548d-3p on RSK4. The proliferation, apoptosis, migration, and invasion of gastric cancer cells were evaluated using MTT assay, propidium iodide (PI), EdU, annexin V-FITC/PI apoptosis detection kit, wound healing assay, and transwell assay after overexpression of miR-548d-3p and RSK4. Finally, a nude mouse tumorigenesis experiment was conducted to explore the role of RSK4-targeting miR-548d-3p in tumorigenesis.

Results

miR-548d-3p negatively regulated the expression of RSK4, resulting in suppressed apoptosis, enhanced proliferation, migration, and invasion of gastric cancer cells, and accelerated tumor growth. In addition, an increase in miR-548d-3p expression enhanced the mRNA levels of CDK2, cyclin A1, cyclin D1, Bax, Bcl-2, N-cadherin, and Vimentin, and decreased E-cadherin mRNA levels by targeting RSK4.

Conclusion

miR-548d-3p promotes gastric cancer by lowering the expression of RSK4.

Circular RNA hsa_circ_0001829 promotes gastric cancer progression through miR-155-5p/SMAD2 axis

Background

Accumulating evidences have shown that circular RNAs (circRNAs) play important roles in regulating the pathogenesis of cancer. However, the role of circRNAs in gastric cancer (GC) remains largely unclear.

Methods

In this study, we identified a novel upregulated circRNA, hsa_circ_0001829, in chemically induced malignant transformed human gastric epithelial cells using RNA-seq. Subsequent qRT-PCR and ISH assays were performed to detect the expression level of hsa_circ_0001829 in GC cell lines and tissues. Functional roles of hsa_circ_0001829 in GC were then explored by loss- and gain-of- function assays. Bioinformatic prediction and luciferase assay were used to investigate potential mechanisms of hsa_circ_0001829. Finally, the mice xenograft and metastasis models were constructed to assess the function of hsa_circ_0001829 in vivo.

Results

We found that hsa_circ_0001829 was significantly upregulated in GC tissues and cell lines. Loss- and gain-of- function assays showed that hsa_circ_0001829 promotes GC cells proliferation, migration and invasion, and the affected cell cycle progression and apoptosis rates may account for the effect of hsa_circ_0001829 on GC proliferation. In addition, bioinformatic prediction and luciferase assay showed that hsa_circ_0001829 acts as a molecular sponge for miR-155-5p and that SMAD2 was a target gene of miR-155-5p; moreover, hsa_circ_0001829 sponges miR-155-5p to regulate SMAD2 expression and hsa_circ_0001829 promotes GC progression through the miR-155-5p–SMAD2 pathway. Finally, suppression of hsa_circ_0001829 expression inhibited tumor growth and aggressiveness in vivo.

Conclusion

Taken together, our findings firstly demonstrated a novel oncogenic role of hsa_circ_0001829 in GC progression through miR-155-5p–SMAD2 axis, and our study may offer novel biomarkers and therapeutic targets for GC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-020-01790-w.