Hsa_circ_0003159 inhibits gastric cancer progression by regulating miR-223-3p/NDRG1 axis

A review on the role of NDRG1 in different cancers

NDRG1 is a member of the α/β hydrolase superfamily that resides in the cytoplasm and participates in the stress responses, hormone response, cell growth, and differentiation. Several studies have pointed to the importance of NDRG1 in the carcinogenesis. This gene has been found to be up-regulated in an array of cancer types such as bladder, esophageal squamous cell carcinoma, endometrial, lung and liver cancers, but being down-regulated in other types of cancers such as colorectal, gastric and ovarian cancers. The current study summarizes the evidence on the role of NDRG1 in the carcinogenic processes in different types of tissues.

Circ_SNX27 regulates hepatocellular carcinoma development via miR-637/FGFR1 axis

BACKGROUND

Circular RNAs (circRNAs) serve as critical regulatory factors in cancer development. Nonetheless, the potential regulatory mechanism of circRNA sorting nexin 27 (circ_SNX27) in hepatocellular carcinoma (HCC) is still unknown.

METHODS

The circ_SNX27, microRNA-637 (miR-637), and fibroblast growth factor receptor 1 (FGFR1) levels were quantified by quantitative real-time polymerase chain reaction and western blot analysis. Next, function experiments were conducted using in vitro assays and in vivo senograft study. The relationship between miR-637 with circ_SNX27 or FGFR1 was uncovered by dual-luciferase reporter and RNA pull-down assays.

RESULTS

The circ_SNX27 and FGFR1 levels were up-regulated, but miR-637 content was reduced in HCC. Circ_SNX27 down-regulation inhibited HCC cell proliferation, motility, and invasion and promoted apoptosis in vitro, as well as weakened tumor growth in vivo. Circ_SNX27 served as a sponge of miR-637 to promote FGFR1 expression. MiR-637 reduction abolished the restrained effect of circ_SNX27 absence on HCC cell development. Moreover, miR-637 curbed HCC cell malignant phenotype by regulating FGFR1.

CONCLUSION

Circ_SNX27 contributed to HCC development via miR-637/FGFR1 axis, offering a new idea for the treatment of HCC.

Functional properties of circular RNAs and research progress in gastric cancer

Circular RNAs (circRNAs) are a class of closed circular non-coding RNAs widely exist in eukaryotes, with high stability and species conservation. A large number of studies have shown that circRNAs are abnormally expressed in various tumor tissues, and are abundant in plasma with long half-life and high specificity, which may be served as potential tumor biomarkers for early diagnosis, treatment and prognosis of malignant tumors. However, the role of circRNAs is still poorly understood in gastric cancer. This article reviews the research progress of circRNAs in gastric cancer in recent years so as to explore the relationship between circRNAs and the occurrence and the development of gastric cancer, and provide new ideas for the diagnosis and treatment of gastric cancer.

Icariin Regulates the hsa_circ_0003159/eIF4A3/bcl-2 Axis to Promote Gastric Cancer Cell Apoptosis

Objective

To clarify the mechanism of icariin (ICA) promoting gastric cancer (GC) cell apoptosis by regulating circ_0003159/eIF4A3/bcl-2 axis.

Methods

The mRNA or protein levels were detected by qRT-PCR or the western blot. The interaction between eIF4A3 protein and circ_0003159 or eIF4A3 protein and bcl-2 mRNA were validated by RNA pull down assays and the RNA immunoprecipitation (RIP) assay. The cell viability was measured by the cell counting kit (CCK)-8 kit. The cell apoptosis was measured by flow cytometry.

Results

Compared with the group Vector, the ratio of cytoplasmic eIF4A3/nuclear eIF4A3 in the cell with circ_0003159 overexpression was significantly higher. RIP and RNA pull down results proved the interaction between eIF4A3 and circ_0003159. The RIP assay further validated the interaction between eIF4A3 and bcl-2. By gain or loss of the functional experiment, hsa_circ_0003159 was proved to recruit eIF4A3 to inhibit bcl-2 expression. Hsa_circ_0003159 regulates eIF4A3/bcl-2 to reduce GC cell viability and increase apoptosis Furthermore, ICA regulates hsa_circ_0003159/eIF4A3/bcl-2 axis to inhibit GC cell activity and induce GC cell apoptosis in vitro.

Conclusion

These data showed that ICA could effectively reduce the GC cell activity and induce GC cell apoptosis via hsa_circ_0003159/eIF4A3/bcl-2 axis, which provides new theoretical evidence for the treatment of GC by ICA.

Circular RNA circPFKP suppresses the proliferation and metastasis of gastric cancer cell via sponging miR-644 and regulating ADAMTSL5 expression

The treatment of gastric cancer (GC) is extremely challenging; however, the specific pathogenesis of GC remains unclear. Circular RNAs (CircRNAs) are non-coding RNAs that can regulate gene expression both transcriptionally and post-transcriptionally. However, little is known about the circRNAs that are important in the progression of GC. This study identified significantly dysregulated circRNAs by analyzing gastric cancer patients and normal control tissues. The target gene was predicted using online bioinformatics tools and verified using RNA pull-down and luciferase reporter assays. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting were used to evaluate gene and protein expression. The malignant behavior of GC cells was determined using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay, wound healing assay, Transwell invasion assay, and flow cytometry. CircPFKP is downregulated in GC tissues, and overexpression of circPFKP inhibits malignant behavior in GC cells. Bioinformatics predicted that circPFKP could bind to miR-644, and miR-644 could target disintegrin-like and metalloprotease domain-containing thrombospondin type 1 motif-like 5 (ADAMTSL5). Overexpression of circPFKP enhances the expression of ADAMTSL5 by decreasing the expression of miR-644 to suppress the growth of xenograft GC tumors in vivo and in vitro. In conclusion, the circPFKP/miR-644/ADAMTSL5 regulatory pathway inhibited the malignant progression of GC. These findings may extend our understanding of the effects of circRNAs on cancer development and provide novel targets for the diagnosis of GC.

Deciphering a Novel Necroptosis-Related miRNA Signature for Predicting the Prognosis of Clear Cell Renal Carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most common histological and devastating subtype of renal cell carcinoma. Necroptosis is a form of programmed cell death that causes prominent inflammatory responses. miRNAs play a significant role in cancer progression through necroptosis. However, the prognostic value of necroptosis-related miRNAs remains ambiguous. In this study, 39 necroptosis-related miRNAs (NRMs) were extracted and 17 differentially expressed NRMs between normal and tumor samples were identified using data form The Cancer Genome Atlas (TCGA). After applying univariate Cox proportional hazard regression analysis and LASSO Cox regression model, six necroptosis-related miRNA signatures were identified in the training cohort and their expression levels were verified by qRT-PCR. Using the expression levels of these miRNAs, all patients were divided into the high- and low-risk groups. Patients in the high-risk group showed poor overall survival (P < 0.0001). Time-dependent ROC curves confirmed the good performance of our signature. The results were verified in the testing cohort and the entire TCGA cohort. Univariate and multivariate Cox regression models demonstrated that the risk score was an independent prognostic factor. Additionally, a predictive nomogram with good performance was constructed to enhance the implementation of the constructed signature in a clinical setting. We then employed miRBD, miRTarBase, and TargetScan to predict the target genes of six necroptosis-related miRNAs. Gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses indicated that 392 potential target genes were enriched in cell proliferation-related biological processes. Six miRNAs and 59 differentially expressed target genes were used to construct an miRNA–mRNA interaction network, and 11 hub genes were selected for survival and tumor infiltration analysis. Drug sensitivity analysis revealed potential drugs that may contribute to cancer management. Hence, necroptosis-related genes play an important role in cancer biology. We developed, for the first time, a necroptosis-related miRNA signature to predict ccRCC prognosis.

miR-223-3p carried by cancer-associated fibroblast microvesicles targets SORBS1 to modulate the progression of gastric cancer

Background

Cancer-associated fibroblasts (CAFs) aggravate gastric cancer (GC) development.

Methods

Combined with bioinformatics analysis and literature review, miR-223-3p had high expression in microvesicles (MVs) derived from GC CAFs, and it could modulate SORBS1. miR-223-3p and SORBS1 mRNA levels were assessed by qRT-PCR. The levels of CAFs markers, MVs markers, epithelial-mesenchymal transition (EMT)-associated proteins, and SORBS1 protein were assessed by western blot. MVs isolated from fibroblasts were observed by transmission electron microscopy. Combined with immunofluorescence and co-culture experiments, GC cells were determined to absorb MVs carrying miR-223-3p. Cell functions were measured using CCK-8, transwell, flow cytometry and colony formation assays. The binding of miR-223-3p and SORBS1 was determined by dual-luciferase assay and RNA immunoprecipitation. The cancer-promoting effect of MVs carrying miR-223-3p on experimental animals was verified in vivo by tumor-bearing experiment in nude mice.

Results

miR-223-3p was upregulated in the MVs secreted by GC CAFs and could be transmitted to GC cells through MVs, to boost the malignant progression of tumor cells. Additionally, it was also revealed that miR-223-3p targeted SORBS1 and accelerated progression along with EMT in GC.

Conclusions

CAFs-derived MVs could carry miR-223-3p to GC cells to target SORBS1, thereby promoting the malignant progression of GC.

SP1-Mediated Upregulation of circFAM126A Promotes Proliferation and Epithelial-Mesenchymal Transition of Oral Squamous Cell Carcinoma via Regulation of RAB41

Background

Accumulating evidence indicates that circular RNAs have major roles in the progression of human cancers. Nevertheless, the molecular mechanism and effects of circFAM126A in oral squamous cell carcinoma (OSCC) remain unclear.

Methods

Quantitative real-time PCR (qRT-PCR) was used to detect expression levels of circFAM126A in OSCC tumor tissues and cell lines; the effects of circFAM126A small hairpin RNA (shRNA) on the proliferation, migration, and invasion of OSCC cells were detected by MTT, colony formation, and transwell assays; xenograft mouse models were used to determine the effects of circFAM126A shRNA on the growth of OSCC tumors in vivo; the expression of miR-186 and RAB41 in OSCC tissues and cells was examined by qRT-PCR; the targeting relationship between circFAM126A and miR-186 was verified by dual-luciferase reporter and RNA pull-down assays; and the relationship between miR-186 and RAB41 was explored.

Results

The expression of circFAM126A was significantly upregulated in OSCC tissues and cells. The transcription factor SP1 transcriptionally activated circFAM126A. However, knockdown of circFAM126A markedly suppressed the proliferation, migration, and invasion of OSCC cells in vitro and inhibited tumor growth and distant metastasis in vivo. Moreover, circFAM126A increased the expression of RAB41 and promoted its mRNA stability via binding to miR-186 and RNA-binding protein FUS. Overexpression of RAB41 antagonized the effects of circFAM126A knockdown and induced an aggressive phenotype of OSCC cells.

Conclusion

SP1 transcriptionally activated circFAM126A modulated the growth, epithelial-mesenchymal transition (EMT) of OSCC cells via targeting the miR-186/FUS/RAB41 axis, suggesting that circFAM126A is a potential biomarker for the treatment of OSCC.

Circ_0003159 upregulates LIFR expression through competitively binding to miR-221-3p/miR-222-3p to block gastric cancer development

Gastric cancer (GC) remains a major cause of cancer-related deaths. Increasing studies suggest that cancer development is accompanied by the deregulation of circular RNAs. We investigated the function of circ_0003159 in GC. The expression levels of circ_0003159, miR-221-3p/miR-222-3p and leukemia inhibitory factor receptor (LIFR) mRNA were measured by real-time quantitative polymerase chain reaction. Cell colony formation ability was assessed by colony formation assay, and cell viability was assessed by cell counting kit-8 assay. Cell apoptosis was assessed by flow cytometry assay and caspase3 activity. Cell migration and invasion were assessed by transwell assay. Glycolysis energy metabolism was assessed by 5'-triphosphate production, glucose uptake and lactate production. The protein levels of related marker proteins and LIFR were detected by western blot. The relationship between circ_0003159 and miR-221-3p/miR-222-3p, or LIFR and miR-221-3p/miR-222-3p was obtained from bioinformatics tools and verified by dual-luciferase reporter assay. A cancer tumorogenicity xenograft experiment in nude mice was conducted to determine the role of circ_0003159 in tumor growth by AGS cells. Our results showed that circ_0003159 expression was decreased in GC tissues and cells. Circ_0003159 overexpression sequestered GC cell viability, migration, invasion and glycolysis and induced cell apoptosis. MiR-221-3p and miR-222-3p were targets of circ_0003159, and the inhibition of miR-221-3p and miR-222-3p also blocked GC cell viability, migration, invasion and glycolysis and promoted cell apoptosis. LIFR was a common target of miR-221-3p and miR-222-3p. Interestingly, LIFR knockdown reversed the effects of circ_0003159 overexpression on GC cell behaviors. Circ_0003159 increased the expression level of LIFR by targeting miR-221-3p and miR-222-3p. The tumorigenicity assay showed that circ_0003159 overexpression inhibited tumor growth in vivo. In conclusion, circ_0003159 inhibited GC development in vitro and in vivo by enriching the level of LIFR via direct binding to miR-221-3p/miR-222-3p.

Icariin inhibits gastric cancer cell growth by regulating the hsa_circ_0003159/miR-223-3p/NLRP3 signaling axis

This study aimed to clarify the expression and role of hsa_circ_0003159 in gastric carcinogenesis, and validate the protective effects of Icariin (ICA) against gastric cancer (GC) cell growth through the in vitro and in vivo experiments. The levels of hsa_circ_0003159, microRNA (miR)-223-3p and NLRP3 were measured by Quantitative real time Polymerase Chain Reaction or western blot. The cell counting kit (CCK)-8 was used to determine cell proliferation. The target relationship of miR-223-3p/hsa_circ_0003159 and miR-223-3p/NLRP3 was predicted by bioinformatics and validated by the dual-luciferase reporter and pull-down assays. Xenograft model was constructed to assess the roles of hsa_circ_0003159 and protective effects of ICA in GC in vivo. Results showed that hsa_circ_0003159 was downregulated in GC cell lines and its overexpression promoted GC cell viability. MiR-223-3p was identified as a target of hsa_circ_0003159. By competitively sponging miR-223-3p, hsa_circ_0003159 positively regulated NLRP3 expression. MiR-223-3p mimics reversed the suppressive effect of hsa_circ_0003159 on GC cell viability and cell pyroptosis. Importantly, ICA inhibited GC cell viability and triggered GC cell pyroptosis by regulating the hsa_circ_0003159/miR-223-3p/NLRP3 axis in vitro and in vivo. In conclusion, this study indicated ICA inhibits GC cell growth by regulating the hsa_circ_0003159/miR-223-3p/NLRP3 signaling axis. This study not only reveals the mechanism of gastric carcinogenesis but also provides potential molecular targets and therapeutic tools for its treatment.

Plasma Exosomal CircNEK9 Accelerates the Progression of Gastric Cancer via miR-409-3p/MAP7 Axis

BACKGROUND

Exosome-mediated transfer of circular RNAs (circRNAs) is related to gastric cancer (GC) development. CircRNA NIMA-related kinase 9 (circNEK9; hsa_circ_0032683) was reported to be up-regulated in GC.

AIMS

The biological role of circNEK9 and its underlying mechanisms in GC progression were explored.

METHODS

The levels of RNAs and proteins were determined by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot assay. Cell proliferation was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, colony formation assay, and flow cytometry. Wound healing assay and transwell assays were conducted to analyze cell motility. Intermolecular interaction was verified by dual-luciferase reporter assay and RNA pull-down assay. Animal experiments were used to evaluate the role of circNEK9 in the growth of xenograft tumors in vivo.

RESULTS

CircNEK9 was up-regulated in GC tissues and cell lines. CircNEK9 interference suppressed the proliferation and motility of GC cells. CircNEK9 silencing enhanced microRNA-409-3p (miR-409-3p) level through direct interaction. CircNEK9 silencing-mediated influences on the proliferation and metastasis of GC cells were partly overturned by the interference of miR-409-3p. MiR-409-3p directly interacted with microtubule-associated protein 7 (MAP7) messenger RNA (mRNA). MiR-409-3p-induced effects in GC cells were largely counteracted by the overexpression of MAP7. CircNEK9 silencing blocked GC tumor growth in vivo. Exosome-mediated transfer of circNEK9 promoted the motility of recipient GC cells.

CONCLUSIONS

CircNEK9 accelerated the proliferation, migration, and invasion of GC cells through targeting miR-409-3p/MAP7 axis. Plasma exosomal circNEK9 promoted the migration and invasion of recipient GC cells.

One stomach, two subtypes of carcinoma—the differences between distal and proximal gastric cancer

Gastric cancer (GC) is one of the most common malignant tumors of the digestive tract, posing a significant risk to human health. Over the past 10 years, the pathological characteristics and the prognosis of GC have been determined based on the locations of the tumors that were then classified into two types—proximal and distal GC. This review focuses on the differences in epidemiology, etiology, cell source, pathological characteristics, gene expression, molecular markers, manifestations, treatment, prognosis, and prevention between proximal and distal GC to provide guidance and a basis for clinical diagnosis and treatment.

DNMT family induces down-regulation of NDRG1 via DNA methylation and clinicopathological significance in gastric cancer

BACKGROUND

Aberrant DNA methylation of tumor suppressor genes is a common event in the development and progression of gastric cancer (GC). Our previous study showed NDRG1, which could suppress cell invasion and migration, was frequently down-regulated by DNA methylation of its promoter in GC.

PURPOSE AND METHODS

To analyze the relationship between the expression and DNA methylation of NDRG1 and DNA methyltransferase (DNMT) family. We performed a comprehensive comparison analysis using 407 patients including sequencing analysis data of GC from TCGA.

RESULTS

NDRG1 was down-regulated in GC, and was negatively correlative to DNMT1 (r = -0.11, p = 0.03), DNMT3A (r = -0.10, p = 0.01), DNMT3B (r = -0.01, p = 0.88), respectively, whereas the DNA methylation of NDRG1 was positively correlative to DNMT family (DNMT1 r = 0.20, p < 0.01; DNMT3A r = 0.26, p < 0.001; DNMT3B r = 0.03, p = 0.57, respectively). NDRG1 expression was significantly inverse correlated with invasion depth (p = 0.023), but DNMT1 was significantly positive correlated with invasion depth (p = 0.049). DNMT3B was significantly correlated with the degree of tumor cell differentiation (p = 0.030). However, there was no association between the expression of DNMT3A and clinicopathological features. The KM plotter showed that NDRG1 (HR = 0.95, 95% CI [0.8-1.12], p = 0.53) and DNMT1 (HR = 1.04, 95% CI [0.88-1.23], p = 0.67) had no association with prognosis of GC patients, while, DNMT3A (p = 0.0064) and DNMT3B (p = 0.00025) displayed significantly association. But the overall survival of high expression of NDRG1 tended to be prolonged.

CONCLUSION

These data suggest that down-regulation of NDRG1expression in GC may be due to its promoter DNA methylation via DNMT family. The demethylating agent maybe a potential target drug for GC patients.

Circular RNA circVRK1 suppresses the proliferation, migration and invasion of osteosarcoma cells by regulating zinc finger protein ZNF652 expression via microRNA miR-337-3p

Circular RNA is an innovative kind of endogenous non-coding RNA, which could take part in tumorigenesis. Nonetheless, the potential molecular mechanisms of circVRK1 in the progression of osteosarcoma remain unresolved. In the current study, we initially investigated circVRK1 levels in osteosarcoma clinical samples and cell lines by qRT-PCR analysis and northern blot assay. RNase R treatments, RNA stability assay and nucleoplasmic separation assay were conducted to identify the characteristics of circVRK1. We adopted CCK-8, colony formation, wound-healing, and transwell assays to assess the biological effects of circVRK1 on the proliferation, migration, and invasiveness of osteosarcoma cells in vitro. We then constructed a xenograft model in nude mice to confirm the suppressive role of circVRK1 in vivo. Moreover, dual-luciferase reporter, RNA immunoprecipitation, and RNA pull-down assays were utilized to elucidate the underlying molecular mechanisms mediated by circVRK1. We demonstrated that circVRK1 was a stable circular transcript localized in the cytoplasm of osteosarcoma cells, and the down-regulation of circVRK1 in osteosarcoma tissues was related to poor outcome of patients. Meanwhile, over-expressed circVRK1 obviously restrained the growth, migration, and invasion of osteosarcoma in vitro and in vivo. Mechanistically, circVRK1 was assumed to be a microRNA sponge for miR-337-3p, and ZNF652 was the downstream gene of miR-337-3p. CircVRK1 overexpression or miR-337-3p knockdown accelerated ZNF652 expression, and up-regulated miR-337-3p efficiently abolished the promotion of ZNF652 induced by circVRK1. Moreover, rescue experiments have proved that circVRK1 inhibits the progression of osteosarcoma by modulating the miR-337-3p/ZNF652 axis. Therefore, we conclude that circVRK1 promotes ZNF652 expression by sponging miR-337-3p. CircVRK1 serves as a molecule sponge for miR-337-3p and mediates the ceRNA network to promote the expression of ZNF652, thus suppresses osteosarcoma proliferation, migration and invasion.

CircTMCO3 Promotes Gastric Cancer Progression by Regulating miR-577/RAB14 Axis

Background

Growing evidence indicated that circRNAs played major roles in the progression of human cancer. Nevertheless, the molecular mechanism and effects of circTMCO3 in GC are still unclear.

Methods

First, qRT-PCR was used to evaluate the levels of circTMCO3 from GC tissues, GC cells, normal tissues and gastric epithelial cells. Then, the GC cells were transfected to analyze the proliferation, migration and invasion of GC cells by MTT, colony formation and transwell assays. Next, the expressions of miR-577 and RAB14 in GC tissues and cells were examined by qRT-PCR following transfection. The target interaction of circTMCO3-miR-577 and miR-577-RAB14 was explored by the dual-luciferase reporter and RNA pull-down assays. In the end, the growth and viability of GC cells were detected by MTT, colony formation and transwell assays, respectively, following the transfection of GC cells.

Results

In this research, we found circTMCO3 expressions are significantly up-regulated in GC tissues and cells compared with the normal tissues and gastric epithelial cells. We discovered that the knockdown of circTMCO3 remarkably inhibits the proliferation, migration and invasion of GC cells. Besides, through the prediction of binding sites between circTMCO3, miR-577 and RAB14, we discovered miR-577 is a target of circTMCO3 while RAB14 is a target gene of miR-577. Finally, the results demonstrate the overexpression of miR-577 and the silence of RAB14 could inhibit the effects of circTMCO3 on proliferation, migration and invasion in GC cells.

Conclusion

circTMCO3 accelerated the growth and migration of GC cells by regulating miR-577/RAB14 axis.

MicroRNAs' role in the environment-related non-communicable diseases and link to multidrug resistance, regulation, or alteration

The discovery of microRNAs (miRNAs) 20 years ago has advocated a new era of "small molecular genetics." About 2000 miRNAs are present that regulate one third of the genome. MiRNA dysregulated expression arising as a response to our environment insult or stress or changes may contribute to several diseases, namely non-communicable diseases, including tumor growth. Their presence in body fluids, reflecting level alteration in various cancers, merit circulating miRNAs as the "next-generation biomarkers" for early-stage tumor diagnosis and/or prognosis. Herein, we performed a comprehensive literature search focusing on the origin, biosynthesis, and role of miRNAs and summarized the foremost studies centering on miR value as non-invasive biomarkers in different environment-related non-communicable diseases, including various cancer types. Moreover, during chemotherapy, many miRNAs were linked to multidrug resistance, via modulating numerous, environment triggered or not, biological processes and/or pathways that will be highlighted as well.

Silencing circPVT1 enhances radiosensitivity in non-small cell lung cancer by sponging microRNA-1208

BACKGROUND

Radiotherapy is one of main useful therapies in non-small cell lung cancer (NSCLC). Nevertheless, the underlying mechanism between NSCLC cell radiosensitivity and effective treatment remains unclear.

OBJECTIVE

The aim is to explore the relationship between circular (circ) RNA and NSCLC cell radiosensitivity.

METHODS

CircRNA plasmacytoma variant translocation 1 (PVT1) and microRNA (miR)-1208 expression in NSCLC cells were assessed using quantitative reverse transcriptase PCR (qRT-PCR). NSCLC cells were transfected with si-PVT1 or miR-1208 inhibitor and then exposed to irradiation. Cellular biology behaviors were detected using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), Terminal deoxynucleotidyl transferase dUTP Nick-End Labeling (TUNEL), colony formation, invasion and western blot. Additionally, binding between circPVT1 and miR-1208 was testified by dual-luciferase reporter and RIP assay.

RESULTS

CircPVT1 was upregulated in NSCLC cells after irradiation treatment. Silencing circPVT1 induced inhibition of NSCLC cell growth and invasion, accompanied by cell apoptosis and γ-H2AX expression. Moreover, NSCLC cell proliferation and invasion was further inhibited by irradiation treatment in circPVT1-silenced cells, indicating a strong radiosensitivity of NSCLC cells. CircPVT1 functions as a competing endogenous RNA of miR-1208. Silencing miR-1208 reversed NSCLC cell sensitivity response to irradiation and activated PI3K/AKT/mTOR pathway in circPVT1-silenced cells.

CONCLUSIONS

Silencing circPVT1 enhanced radiosensitivity of NSCLC cells by sponging miR-1208.

Histone deacetylase 10 exerts antitumor effects on cervical cancer via a novel microRNA-223/TXNIP/Wnt/β-catenin pathway

Dysfunction of histone deacetylase 10 (HDAC10) has been suggested in the carcinogenesis of cervical cancer (CC). However, its association with microRNAs (miRNAs) in CC remains exclusive. Hence, this study aims to probe the role of HDAC10 in regulating CC cell proliferation, migration, and invasion and its correlation with the screened-out miRNA target. Microarray analysis and RT-qPCR revealed that HDAC10 expressed poorly in CC cells relative to human immortalized endocervical cells (End1/E6E7). Moreover, HDAC10 downregulation predicted poor survival for patients with CC. Overexpression of HDAC10 reduced CC cell biological activities in vitro and tumor growth and lung metastases in vivo. miR-223, upregulated in CC, was regulated by HDAC10 through histone acetylation, while miR-223 inhibited the effects of HDAC10 overexpression in CC. miR-223 targeted the 3'-UTR of thioredoxin interacting protein (TXNIP) and suppressed its expression, leading to increased CC development in vitro and in vivo. TXNIP overexpression impaired Wnt/β-catenin pathway activity in CC cells.

Circ_002059 suppresses cell proliferation and migration of gastric cancer via miR-182/MTSS1 axis

Circular RNAs (circRNAs) play either oncogenic or tumor suppressive roles in gastric cancer (GC). A previous study demonstrated that circ_002059, a typical circRNA, was downregulated in GC tissues. However, the role and mechanism of circ_002059 in GC development are still unknown. In this study, the levels of circ_002059, miR-182, and metastasis suppressor-1 (MTSS1) were examined by real-time quantitative polymerase chain reaction and western blot analysis. Cell proliferation and migration were evaluated by MTT assay and Transwell migration assay, respectively. The interactions between miR-182 and circ_002059 or MTSS1 were analyzed by dual-luciferase reporter assay. A GC xenograft model was established to validate the role of circ_002059 in GC progression in vivo. Overexpression of circ_002059 significantly inhibited, whereas knockdown of circ_002059 notably facilitated, cell proliferation and migration in GC cells. MTSS1 was found to be a direct target of miR-182 and circ_002059 upregulated MTSS1 expression by competitively sponging miR-182. Transfection with miR-182 mimic and MTSS1 silencing abated the inhibitory effect of circ_002059 on GC progression. Circ_002059 inhibited GC cell xenograft tumor growth by regulating miR-182 and MTSS1 expression. Collectively, Circ_002059 inhibited GC cell proliferation and migration in vitro and xenograft tumor growth in mice, by regulating the miR-182/MTSS1 axis.

CircRNAs: a new target for the diagnosis and treatment of digestive system neoplasms

A circRNA is a type of endogenous noncoding RNA that consists of a closed circular RNA molecule formed by reverse splicing; these RNAs are widely distributed in a variety of biological cells. In contrast to linear RNAs, circRNAs have no 5′ cap or 3′ poly(A) tail. They have a stable structure, a high degree of conservation, and high stability, and they are richly and specifically expressed in certain tissues and developmental stages. CircRNAs play a very important role in the occurrence and progression of malignant tumors. According to their origins, circRNAs can be divided into four types: exon-derived circRNAs (ecRNAs), intron-derived circRNAs (ciRNAs), circRNAs containing both exons and introns (EIciRNAs) and intergenic circRNAs. A large number of studies have shown that circRNAs have a variety of biological functions, participate in the regulation of gene expression and play an important role in the occurrence and progression of tumors. In this paper, the structure and function of circRNAs are reviewed, along with their biological role in malignant tumors of the digestive tract, in order to provide a reference for the diagnosis and treatment of digestive system neoplasms.

High miR-324-5p expression predicts unfavorable prognosis of gastric cancer and facilitates tumor progression in tumor cells

Background

Gastric cancer (GCa) is one of the six major malignancies in the world with low survival rate. Although there are advances in therapeutic approaches, the prognosis of patients with GCa remains not optimistic. Therefore, this study aimed to evaluate the prognostic value of miR-324-5p, as well as its functional role in GCa progression.

Methods

The expression of miR-324-5p in tumor tissues and cell lines was examined using real-time quantitative PCR. The prognostic value of miR-324-5p in patients with GCa was evaluated by Kaplan-Meier survival curve and Cox regression analysis. Gain- and loss-of-function experiments were performed to evaluate the biological function of miR-324-5p during the progression of GCa, and a target gene of miR-324-5p was proposed.

Results

The expression of miR-324-5p was up-regulated in GCa tissues and cell lines. Patients with high expression of miR-324-5p had more cases with positive lymph node metastasis, advanced TNM stage, and worse overall survival compared with patients with low expression. The elevated miR-324-5p was an independent prognostic indicator of GCa. In addition, the inhibition of miR-324-5p could suppress GCa cell proliferation, migration and invasion and promote cell apoptosis, and PTEN was demonstrated to serve as a direct target of miR-324-5p in GCa progression.

Conclusion

The present study indicates that miR-324-5p overexpression predicts poor prognosis in GCa patients, and the reduction of miR-324-5p can inhibit GCa biological processes. PTEN is a target gene of GCa, which may mediate the biological function of miR-324-5p in GCa progression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13000-020-01063-2.

Circular RNAs in gastrointestinal cancer: Current knowledge, biomarkers and targeted therapy (Review)

Circular RNAs (circRNAs) are a type of endogenous non‑coding RNAs that are connected at the 3' and 5' ends by exon or intron cyclization, which forms a covalently closed loop. They are stable, well conserved, exhibit specific expression in mammalian cells and can function as microRNA (miRNA or miR) sponges to regulate the target genes of miRNAs, which influences biological processes. Such as tumor proliferation, invasion, metastasis, apoptosis and tumor stage. circRNAs represent promising candidates for clinical diagnosis and treatment. In the present review, the biogenesis, classification and functions of circRNAs in tumors are briefly summarized and discussed. In addition, the participation of circRNAs in signal transduction pathways regulating gastrointestinal cancer cellular functions is highlighted.

Non-coding RNAs in gastric cancer

Non-coding RNAs (ncRNAs) are functional RNA molecules that play crucial regulatory roles in many fundamental biological processes. The dysregulation of ncRNAs is significantly associated with the progression of human cancers, including gastric cancer. In this review, we have summarized the oncogenic or tumor-suppressive roles and the regulatory mechanisms of lncRNAs, miRNAs, circRNAs and piRNAs, and have discussed their potential as biomarkers or therapeutic targets in gastric cancer.

Circular RNAs in Sepsis: Biogenesis, Function, and Clinical Significance

Sepsis is a life-threatening condition that occurs when the body responds to an infection that damages it is own tissues. The major problem in sepsis is rapid, vital status deterioration in patients, which can progress to septic shock with multiple organ failure if not properly treated. As there are no specific treatments, early diagnosis is mandatory to reduce high mortality. Despite more than 170 different biomarkers being postulated, early sepsis diagnosis and prognosis remain a challenge for clinicians. Recent findings propose that circular RNAs (circRNAs) may play a prominent role in regulating the patients’ immune system against different pathogens, including bacteria and viruses. Mounting evidence also suggests that the misregulation of circRNAs is an early event in a wide range of diseases, including sepsis. Despite circRNA levels being altered in sepsis, the specific mechanisms controlling the dysregulation of these noncoding RNAs are not completely elucidated, although many factors are known to affect circRNA biogenesis. Therefore, there is a need to explore the molecular pathways that lead to this disorder. This review describes the role of this new class of regulatory RNAs in sepsis and the feasibility of using circRNAs as diagnostic biomarkers for sepsis, opening up new avenues for circRNA-based medicine.

miR-874 inhibits gastric cancer cell proliferation by targeting SPAG9

Background

microRNAs (miRNAs) play essential roles in the development and progression of gastric cancer (GC). Although aberrant miR-874 expression has been reported in various human cancers, its role in GC remains obscure.

Methods

miR-874 expression was assessed by real-time quantitative polymerase chain reaction (RT-qPCR) in 62 matched GC and adjacent normal tissues, as well as in GC cell lines and immortalized human gastric epithelial cells. CCK8 assay, colony formation assay, and flow cytometry were used to assess the role of miR-874 in GC cell proliferation and apoptosis in vitro. Additionally, to determine the effects of miR-874 on GC cell proliferation and apoptosis in vivo, BALB/c nude mice were injected with GC cells transfected with a miR-874 mimic. The role of miR-874 in SPAG9 expression was assessed by luciferase assay, Western blotting, and RT-qPCR.

Results

miR-874 was downregulated in GC cell lines and tissues. miR-874 overexpression in GC cells led to inhibition of cell proliferation and induction of apoptosis. Moreover, SPAG9 was identified as a direct miR-874 target, the expression of which was suppressed by miR-874. SPAG9 overexpression markedly promoted GC cell proliferation.

Conclusions

miR-874 inhibited cell proliferation and induced apoptosis in GC cells. SPAG9 downregulation was crucial for the tumor-suppressive effects of miR-874. Hence, the miR-874/SPAG9 axis could serve as a novel therapeutic target in GC.