Role of CircRNAs_100395 in Proliferation and Metastases of Liver Cancer

Ruangan Lidan decoction inhibits the growth and metastasis of liver cancer by downregulating miR-9-5p and upregulating PDK4

A growing number of studies have suggested that traditional Chinese medicine (TCM) plays an essential role in the development and occurrence of liver cancer. However, the function of Ruangan Lidan decoction (RLD) in liver cancer are not yet adequately identified and manifested, which attracted our attention. The key genes related to liver cancer and RLD and the upstream miRNAs of PDK4 were obtained based on bioinformatics analysis, followed by verification of the targeting relationship between miR-9-5p and PDK4. Next, Huh7 cells were treated with RLD to detect cell proliferation, colony formation, migration, invasion, and apoptosis by multiple assays with gain- and loss-of-function experiments. Moreover, subcutaneous transplanted tumor model and lung metastasis model of liver cancer in nude mice were established to further verify the functional role of RLD in liver cancer growth and metastasis via miR-9-5p/PDK4 axis. Bioinformatics analysis found that PDK4 and miR-9-5p were related to liver cancer, and PDK4 may be a downstream regulator of RLD. miR-9-5p could target and inhibit PDK4. In vitro cell experiments demonstrated that RLD suppressed liver cancer cell proliferation, invasion and migration, and promoted apoptosis by inhibiting miR-9-5p expression and promoting PDK4 expression. In vivo animal experiments further confirmed that RLD inhibited liver cancer growth and metastasis via upregulation of miR-9-5p-dependent PDK4. RLD downregulated miR-9-5p and upregulated PDK4 to inhibit the proliferation, migration, invasion, and induce apoptosis, thereby suppressing the growth and metastasis of liver cancer, highlighting a potential novel target for treatment of liver cancer.

CircUSP10 promotes liver cancer progression by regulating miR-211-5p/TCF12/EMT signaling pathway

There is no precise diagnosis or prognosis for liver cancer (LC) using a single biomarker. Circular RNAs (circRNAs) contribute to the pathogenesis of different cancers, but their role in LC is not entirely understood. In this study, circUSP10, an aberrantly expressed circRNA in LC, was screened using the Gene Expression Omnibus database, and its tissue-specific expression was verified using qRT-PCR. In vitro, functional assays and nude mouse tumorigenesis models were used to investigate circUSP10 role in LC. RNA immunoprecipitation and dual-luciferase reporter assays were performed to study the mechanistic relationship between circUSP10, miR-211-5p, and transcription factor 12 (TCF12). We found that circUSP10 expression was upregulated in LC tissues and cells. CircUSP10 expression was linked to tumor size and tumor node metastasis stage and negatively correlated with LC prognosis. In vitro assays confirmed circUSP10-mediated proliferation, migration, and invasion of LC cells and their association with the epithelial-mesenchymal transition (EMT) pathway. Mechanistically, circUSP10 adsorbed miR-211-5p, which regulated TCF12 and promoted tumorigenesis via the EMT signaling pathway. Therefore, our results suggest that circUSP10 may promote LC progression by modulating the miR-211-5p/TCF12/EMT signaling cascade and may serve as a potential biomarker for LC diagnosis and prognosis.

Screening differential circular RNA expression profiles and the potential role of hsa_circ_0085465 in liver cancer

Aims

This study aimed to screen the circular RNAs (circRNAs) that are differentially expressed between liver cancer and paired paracarcinoma tissues and then elucidate their role in cancer progression.

Materials and Methods

High-throughput sequencing of cancer and paired paracarcinoma tissues was followed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses of the parental genes of the differentially expressed circRNAs, which were also verified via real-time quantitative polymerase chain reaction analysis of the tissues. In addition, the function of selected circRNAs was determined using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4- sulfophenyl)-2H-tetrazolium (MTS) and transwell assays.

Results

Total 218 and 121 circRNAs were differentially upregulated and downregulated, respectively; these were mainly enriched with GO and KEGG terms related to biological functions. From five representatives of the differentially expressed circRNAs, we selected hsa_circ_0085465 for further analysis, discovering that its overexpression promoted the proliferation, migration, and invasion of 97 L cells.

Conclusion

Taken together, our results suggest that hsa_circ_0085465 is relevant to liver cancer progression.

Fuzheng Xiaozheng prescription exerts anti-hepatocellular carcinoma effects by improving lipid and glucose metabolisms via regulating circRNA-miRNA-mRNA networks

BACKGROUND

Hepatocellular carcinoma (HCC) is a major threat to human health due to its high lethality. Our previous studies suggested that Fuzheng Xiaozheng prescription (FZXZP), an effective Chinese medicine, demonstrated significant suppressive effects on HCC. However, its underlying mechanism remains largely unclear.

PURPOSE

This study aimed to investigate the anti-HCC mechanisms of FZXZP from transcriptomic sequencing based on a holistic perspective.

METHODS

Rat HCC model was induced by diethylnitrosamine, and then the model was administered with two doses of FZXZP, high and low. Sodium demethylcantharidate was used as a positive control. Subsequently, microarrays of circRNA, miRNA and mRNA were performed on the blank, model, high and low dose groups, respectively, and the competitive binding mechanisms among them were further analyzed by bioinformatics. Then, the circRNA-miRNA-mRNA networks were constructed to mine the targeted-RNAs of FZXZP in HCC, as well as to explore their potential regulatory mechanisms. Finally, functions and pathways of the FZXZP targeted genes in rat HCC were annotated with GO and KEGG, and qRT-PCR was performed to validate the accuracy of the above analyses in this study.

RESULTS

The results showed that FZXZP significantly inhibited the development and progression of HCC in rats, improved the pathological conditions and suppressed the proliferation of HCC cells. Subsequently, after a series of screening, the competing endogenous RNA networks (circRNA-miRNA-mRNA), consisting of 2 circRNAs, 7 miRNAs and 104 mRNAs, were finally established. KEGG and GO analyses of the networks revealed that lipid metabolism related pathways, such as fatty acid metabolism, bile secretion and PPAR pathway, were significantly enriched. In the further hubgene network analysis, in addition to lipid metabolism, aberrant glucose metabolism was found to be ameliorated by G6pc and Pklr in hubgenes. Finally, the qRT-PCR analyses confirmed that the expression tendencies of the above targeted genes were correct and believable in transcriptomic sequencings, and qRT-PCR results of the genes closely related to proliferation, invasion and apoptosis of HCC also indicated the inhibitory effects of FZXZP on HCC obviously.

CONCLUSION

FZXZP demonstrated significant anti-HCC effects through improving lipid and glucose metabolism, restoring the metabolic homeostasis of the liver via circRNA-miRNA-mRNA networks.

CircFMN2 Boosts Sorafenib Resistance in Hepatocellular Carcinoma Cells via Upregulating CNBP by Restraining Ubiquitination

Purpose

Noncoding RNAs exert critical biological effects in hepatocellular carcinoma (HCC). The role of circFMN2, a newly discovered functional RNA in prostate cancer and colorectal cancer, was investigated for the first time in sorafenib-resistance HCC cells.

Methods

The level of circFMN2 was assessed via quantitative real-time PCR (qRT-PCR). Cell proliferation was detected via CCK-8 and colony formation assay. Cell apoptosis was measured via the TUNEL assay and flow cytometry analysis. A Western blot assay was conducted to detect the CCHC-type zinc finger nucleic acid binding protein (CNBP) level and ubiquitination. RNA pull-down assay and RNA immunoprecipitation were carried out to explore the interaction between circFMN2 and CNBP.

Results

CircFMN2 was highly expressed in multidrug-resistant (MDR) cells. CircFMN2 overexpression exerted pro-proliferation effects in sorafenib-treated HCC cells, while depletion of circFMN2 displayed negative effect on sorafenib-treated MDR cells. Moreover, CNBP was verified as the binding protein of circFMN2. CNBP was upregulated in MDR cells, which was achieved by inhibition of ubiquitination by circFMN2. Besides, CNBP overexpression was found to boost sorafenib resistance in HCC cells.

Conclusions

CircFMN2 is aberrantly expressed in sorafenib-resistant HCC cells and contributes to sorafenib resistance in HCC cells via upregulation of CNBP by restraining ubiquitination.

Circular RNAs in hepatocellular carcinoma: Recent advances

Circular RNAs (circRNAs) have covalently closed loop structures at both ends, exhibiting characteristics dissimilar to those of linear RNAs. Emerging evidence suggests that aberrantly expressed circRNAs play crucial roles in hepatocellular carcinoma (HCC) by affecting the proliferation, apoptosis and invasive capacity of HCC cells. Certain circRNAs may be used as biomarkers to diagnose and predict the prognosis of HCC. Therefore, circRNAs are expected to become novel biomarkers and therapeutic targets for HCC. Herein, we briefly review the characteristics and biological functions of circRNAs, focusing on their roles in HCC to provide new insights for the early diagnosis and targeted therapy of HCC.

Circ_0041732 regulates tumor properties of triple-negative breast cancer cells by the miR-149-5p/FGF5 pathway

BACKGROUND

Triple-negative breast cancer (TNBC) is a subtype of breast cancers with a high recurrence and mortality. The important factors promoting the TNBC process have not been fully identified. In this research, the role of a TNBC-related circular RNA (circRNA), circ_0041732, was revealed in TNBC cell tumor properties.

METHODS

The expression levels of circ_0041732, microRNA-149-5p (miR-149-5p) and fibroblast growth factor 5 (FGF5) were detected by quantitative real-time polymerase chain reaction. The protein expression was determined by Western blot analysis or immunohistochemistry assay. Cell proliferation was detected by cell counting kit-8 and cell colony formation assays. Cell apoptosis was analyzed by flow cytometry and caspase-3 activity assays. Cell migration and invasion were evaluated by wound-healing and transwell invasion assays. Cell angiogenic capacity was investigated by a tube formation assay. The targeting relationship between miR-149-5p and circ_0041732 or FGF5 was identified by dual-luciferase reporter and RNA immunoprecipitation assays. The impacts of circ_0041732 knockdown on tumor formation were determined by an in vivo assay.

RESULTS

Circ_0041732 and FGF5 expression were significantly upregulated, whereas miR-149-5p was downregulated in TNBC tissues and cells compared with normal breast tissues and cells, respectively. Circ_0041732 silencing inhibited TNBC cell proliferation, migration, invasion, and tube formation, but induced apoptosis. Additionally, circ_0041732 regulated TNBC cell tumor properties by binding to miR-149-5p. MiR-149-5p also modulated TNBC cell tumor properties by targeting FGF5. Furthermore, circ_0041732 knockdown hindered tumor formation in vivo.

CONCLUSION

Circ_0041732 silencing suppressed TNBC cell tumor properties by decreasing FGF5 expression through miR-149-5p. This finding demonstrated that circ_0041732 had the potential as a therapeutic target for TNBC.

Circ_0000212 affects proliferation, migration, invasion, apoptosis, and paclitaxel sensitivity of liver cancer cells by targeting miR-139-5p

BACKGROUND

Circ_0000212 is a newly discovered non-coding RNA whose high expression promotes the progression of colorectal cancer. However, the expression patterns and roles of circ_0000212 in liver cancer remain unknown.

AIM

To investigate the effect of circ_0000212 targeting miR-139-5p on cell proliferation, migration, invasion, apoptosis, and paclitaxel sensitivity in liver cancer.

METHODS

RT-qPCR was applied to detect the expression of circ_0000212 and miR-139-5p in liver cancer tissues and adjacent tissues. Pearson correlation analysis was performed to determine the relationship between circ_0000212 and miR-139-5p expression in liver cancer tissues. Dual luciferase reporter assay was used to verify the targeting relationship between circ_0000212 and miR-139-5p. Liver cancer HCC9204 cells were divided into a control group, circ_0000212 interference group, circ_0000212 interference + miR-139-5p inhibitor group, paclitaxel group, paclitaxel + circ_0000212 interference group, and paclitaxel + circ_0000212 interference + miR-139-5p inhibitor group. The rate of inhibited HCC9204 cells was detected using CCK-8 method; the number of clones formed by HCC9204 cells was calculated using colony formation assay; the apoptotic rate of HCC9204 cells was evaluated by flow cytometry; and the migration and invasion of HCC9204 cells were detected by Transwell assay.

RESULTS

Compared with adjacent tissue, the expression level of circ_0000212 in liver cancer tissue was significantly increased (P < 0.05), while the expression level of miR-139-5p was significantly decreased (P < 0.05). There was a negative correlation between the expression of circ_0000212 and miR-139-5p in liver cancer tissues. Circ_0000212 directly interacted with miR-139-5p. Compared with the control group, circ_0000212 expression in HCC9204 cells in the paclitaxel group was significantly reduced (P < 0.05), while miR-139-5p expression was significantly increased (P < 0.05). Compared with the control group, the numbers of clones formed and migrating and invading HCC9204 cells in the interference circ_0000212 group and paclitaxel group were significantly reduced (P < 0.05), and the inhibition rate and apoptosis rate were significantly increased (P < 0.05). Compared with the circ_0000212 interference group, the numbers of clone formed and migrating and invading HCC9204 cells in the interference circ_0000212+miR-139-5p inhibitor group were significantly increased (P < 0.05), and the inhibition rate and apoptosis rate were significantly reduced (P < 0.05). Compared with the paclitaxel group, the numbers of clones formed and migrating and invading HCC9204 cells in the paclitaxel + circ_0000212 interference group were significantly reduced (P < 0.05), and the inhibition rate and apoptosis rate were significantly increased (P < 0.05). Compared with the paclitaxel + circ_0000212 interference group, the numbers of clones formed and migrating and invading HCC9204 cells in the paclitaxel + circ_0000212 interference + miR-139-5p inhibitor group were significantly increased (P < 0.05), and the inhibition rate and apoptosis rate were significantly reduced (P < 0.05).

CONCLUSION

Interfering with circ_0000212 can inhibit cell proliferation, migration, and invasion, induce cell apoptosis, and increase its sensitivity to paclitaxel in liver cancer cells by targeting and up-regulating miR-139-5p.

Circular RNA hsa_circ_0026552 inhibits the proliferation, migration and invasion of trophoblast cells via the miR‑331‑3p/TGF‑βR1 axis in pre‑eclampsia

Globally, pre-eclampsia (PE) is a gestational disorder that causes increased morbidity of the fetus and mortality induced by pregnancy. Despite various studies, the understanding of the causes or mechanism of the development of PE remains elusive. Thus, the present study aimed to investigate the role of circular (circ)RNA hsa_circ_0026552 (hsa_circ_0026552) in the development of PE and its mechanism of regulation. hsa_circ_0026552 differential expression in PE tissue data and clinical samples were analyzed and it was observed that hsa_circ_0026552 is highly upregulated in PE samples. Furthermore, miR-331-3p was detected as an hsa_circ_0026552 target miRNA and TGF-βR1 gene as a target of miR-331-3p. These results were confirmed using various assays, including dual-luciferase reporter, reverse transcription-quantitative PCR and RNA pull-down assay. It was observed that miR-331-3p expression was negatively correlated to hsa_circ_0026552 relative expression, while TGF-βR1 expression was positively correlated to hsa_circ_0026552 expression evaluated by Pearson's correlation test. The functional experiments, including Cell Counting Kit-8, colony formation and Transwell assay, showed that silencing hsa_circ_0026552 could significantly strengthen the proliferation, migration and invasion of the trophoblastic HTR-8/SVneo cells, but the subsequent overexpression of hsa_circ_0026552 reversed this. Mechanistically, it was concluded that hsa_circ_0026552 acts as a miR-331-3p sponge to upregulate TGF-βR1 expression in trophoblasts and is involved significantly in PE development and progression in pregnant women. The circRNA hsa_circ_0026552 could be a novel therapeutic target and prognostic biomarker for PE.

Silencing of circ_0000517 suppresses proliferation, glycolysis, and glutamine decomposition of non-small cell lung cancer by modulating miR-330-5p/YY1 signal pathway

In recent years, circular RNA (circRNA) has been found to be involved in a variety of cancer processes. More and more attention has been paid to the research of circRNA in lung cancer. This study aims to investigate whether circ_0000517 affected the physiology of non-small cell lung cancer (NSCLC) and the underlying mechanism. The results demonstrated that circ_0000517 was highly expressed in lung cancer tissues and cells, and overexpression of circ_0000517 was negatively correlated with the prognosis of NSCLC patients. Silencing of circ_0000517 significantly inhibited the proliferation, glycolysis, and glutamine decomposition of NSCLC cells in vitro and repressed the growth of xenografted tumors in vivo. Moreover, knockdown of circ_0000517 attenuated the expression of PCNA, HK2, LDHA, ASCT2, and GLS1. Further study found that circ_0000517 targeted miR-330-5p and miR-330-5p targeted YY1. In addition, miR-330-5p inhibitor reversed inhibition of cancer cell proliferation, glycolysis, and glutamine decomposition induced by si-circ_0000517. In conclusion, our study revealed that silencing of circ_0000517 improved the progression of NSCLC through regulating miR-330-5p/YY1 axis.

Inhibitory role of circRNA_100395 in the proliferation and metastasis of prostate cancer cells

OBJECTIVE

Circular RNAs (circRNAs) are non-coding RNAs with high cancer-specific expression and the potential for regulating tumorigenesis. CircRNA_100395 is expressed at low levels in many cancers and is involved in the regulation of tumor cell proliferation and metastasis. However, its expression and function in prostate cancer remain unclear.

METHODS

Endogenous expression levels of circRNA_100395 and microRNA-1228 (miR-1228) in prostate cancer tissue samples and cell lines were detected by quantitative reverse transcription-polymerase chain reaction. Cell proliferation, invasion, and migration, cell cycle distribution, and epithelial-mesenchymal transition (EMT) were analyzed in circRNA_100395-overexpressing prostate cancer cells by Cell Counting Kit-8, flow cytometry, Transwell assay, and western blotting, respectively.

RESULTS

CircRNA_100395 expression was downregulated in cancerous prostate tissues relative to adjacent normal tissues. CircRNA_100395 expression was negatively correlated with tumor size, Gleason score, tumor stage, and lymph node metastasis. Moreover, circRNA_100395 overexpression inhibited cell proliferation, altered cell cycle distribution, reduced cell migration and invasion abilities, and suppressed EMT in prostate cancer cells. Moreover, miR-1228 was a direct downstream target of circRNA_100395, and the anti-tumor ability of circRNA_100395 was significantly reversed by miR-1228.

CONCLUSION

This study identified circRNA_100395 as an anti-tumor circRNA and a potential therapeutic target for prostate cancer.

Upregulation of circRNA_100395 sponges miR-142-3p to inhibit gastric cancer progression by targeting the PI3K/AKT axis

Gastric cancer (GC) has a high morbidity and mortality, hence it is very important to elucidate the molecular pathogenesis mechanism of GC progression in order to find new treatment strategies. The present study aimed to explore the biological function of circular RNA_100395 (circRNA_100395) in GC. The expression level of circRNA_100395 in GC tissues, as well as normal epithelial cells and various gastric cancer cell lines, was detected using reverse transcription-quantitative PCR. Cell Counting Kit-8, EdU assay, flow cytometry and Transwell assays were performed to investigate cell proliferation, apoptosis, migration and invasion, respectively. A dual-luciferase reporter assay was performed to detect the correlation between circRNA_100395 and micro (mi)RNA-142-3p. Western blotting was performed to elucidate the potential regulatory mechanism. circRNA_100395 expression was found to be increased in GC tissues and cell lines. However, miR-142-3p expression was significantly reduced. Besides, low expression levels of circRNA_100395 were associated with poor tumor differentiation, advanced Tumor-Node-Metastasis stage, lymph node metastasis and shorter overall survival time. Moreover, overexpression of circRNA_100395 suppressed cell proliferation, increased the apoptosis rate and suppressed cell invasion and migration by inhibiting the PI3K/AKT signaling pathway. These findings also showed that miRNA-142-3p rescued the antitumor effects induced by circRNA_100395-overexpression. cirRNA_100395-overexpression had antitumor effects via regulating the miR-142-3p signaling pathway, which might be a promising treatment target for GC.

CircRNA_100395 Carried by Exosomes From Adipose-Derived Mesenchymal Stem Cells Inhibits the Malignant Transformation of Non-Small Cell Lung Carcinoma Through the miR-141-3p-LATS2 Axis

OBJECTIVE

The specific purpose of this study is to investigate the impact exosomes from adipose-derived mesenchymal stem cell (AMSC) has on non-small cell lung carcinoma (NSCLC) and the relative applications.

METHODS

circ_100395, miR-141-3p, and LATS2 were expressed and detected in NSCLC and paracancerous tissues as well as NSCLC cell lines. Pearson correlation analysis, Dual-Luciferase Reporter Assay and RNA pull-down assay were used to validate their expression and interaction, respectively. After isolation and culture of AMSCs, exosomes were extracted and identified. EdU, epithelial-mesenchymal transition (EMT), and cell colony formation assay were used to distinguish the biological activity of the cells. Expression Hippo/YAP signalling pathway-related proteins were measured by western blotting. Subsequently, tumour volume and weight were confirmed based on xenograft nude mice models, Ki-67 and LATS2 expression was observed by immunohistochemistry.

RESULTS

circ_100395 was lowly expressed in NSCLC tissues or cells. The negative correlations and interactions were confirmed between circ_100395 and miR-141-3p, miR-141-3p, and LATS2. AMSC-derived exosomes with overexpression of circ_100395 (exo-circ_100395) significantly inhibited the biological activity as well as EMT of H1650 cells and Hippo/YAP signalling pathway activity. In addition, exo-circ_100395 markedly reduced tumour volume and weight as well as Ki-67 and LASP1 expression in vivo. However, overexpressed miR-141-3p or knocked down LATS2 alleviated the above effects.

CONCLUSION

Exo-circ_100395 can increase LATS2 expression by sponging miR-141-3p to regulate Hippo/YAP signalling pathway, thereby inhibiting NSCLC malignant transformation.

Circular RNA_0074027 participates in cell proliferation, apoptosis and metastasis of colorectal cancer cells through regulation of miR‑525‑3p

The present study aimed to elucidate the biological function of circular RNAs (circRNA) 0074027 in colorectal cancer (CRC). The expression of circRNA‑0074027 in CRC tissues and cells was determined by reverse transcription‑quantitative PCR. The in vitro experiments, including Cell Counting Kit‑8 (CCK‑8) assay, 5‑Ethynyl‑2'‑deoxyuridine assay, flow cytometry and Transwell assay, were applied to evaluate cell proliferation, apoptosis and metastasis ability respectively following downregulation of circRNA‑0074027. The correlation between circRNA‑0074027 and micro (mi)RNA‑525‑3p was determined via dual‑luciferase reporter assay. Finally, western blotting was used to explore the possible regulatory mechanism. CircRNA‑0074027 was upregulated in CRC tissues, while miR‑525‑3p expression was reduced. In addition, patients with CRC and circRNA‑0074027 overexpression were more likely to have low tumor differentiation, lymph node metastasis and advanced TMN stage. Deletion of circRNA‑0074027 could suppress cell proliferation and metastasis through up-regulating p53 expression and forbidding epithelial‑mesenchymal transition signaling pathway. The addition of miRNA‑525‑3p inhibitors could reverse the anti‑tumor effects induced by the deletion of circRNA‑0074027. The downregulation of cirRNA_0074027 inhibited tumor progression via sponging miR‑525‑3p, which could be a promising treatment bio‑marker for CRC.

Biological roles and potential clinical values of circular RNAs in gastrointestinal malignancies

Circular RNAs (circRNAs), a class of endogenous RNA molecules, are produced by alternative splicing of precursor RNA and are covalently linked at the 5' and 3' ends. Recent studies have revealed that dysregulated circRNAs are closely related to the occurrence and progression of gastrointestinal malignancies. Accumulating evidence indicates that circRNAs, including circPVT1, circLARP4, circ-SFMBT2, cir-ITCH, circRNA_100782, circ_100395, circ-DONSON, hsa_circ_0001368, circNRIP1, circFAT1(e2), circCCDC66, circSMARCA5, circ-ZNF652, and circ_0030235 play important roles in the proliferation, differentiation, invasion, and metastasis of cancer cells through a variety of mechanisms, such as acting as microRNA sponges, interacting with RNA-binding proteins, regulating gene transcription and alternative splicing, and being translated into proteins. With the characteristics of high abundance, high stability, extensive functions, and certain tissue-, time- and disease-specific expressions, circRNAs are expected to provide novel perspectives for the diagnoses and treatments of gastrointestinal malignancies.

circ_NOTCH3 Functions as a Protooncogene Competing With miR-205-5p, Modulating KLF12 Expression and Promoting the Development and Progression of Basal-Like Breast Carcinoma

Breast cancer is the most common type of cancer diagnosed among women, and basal-like breast carcinoma (BLBC) has been associated with a more aggressive histology, poorer prognosis, and non-responsiveness to hormone therapy. In the present study, the role and molecular mechanism of circular (circ)_NOTCH3 in the development and progression for BLBC was identified. circ_RNAs array was used to screen the ectopic expression of hsa_circ_0109177 (circ_NOTCH3) in BLBC. RT-qPCR was conducted to evaluate the circ_NOTCH3 expression in BLBC tissues and paired normal tissues, as well as related cell lines. Cell function changes were analyzed following circ_NOTCH3 or micro (mi)RNA overexpression or co-expression. Bioinformatics analysis and dual-luciferase reporter assay were performed to predict and verify the binding sites between circ_NOTCH3 and miRNAs. Gene expression changes were assessed using western blotting. circ_NOTCH3 had a significantly higher expression in BLBC tissues and cell lines. The upregulation of circ_NOTCH3 promoted the proliferation, migration, invasion and inhibited the apoptosis for BLBC cells. The opposite results were observed following miR-205-5p overexpression. However, the co-expression of circ_NOTCH3 and miR-205-5p resulted in those restoration. circ_NOTCH3 is capable of binding to miR-205-5p, and upregulating its target gene KLF12, which can be downregulated by miR-205-5p overexpression and restored by the co-expression of circ_NOTCH3 and miR205-5p. circ_NOTCH3, being an protooncogene and a powerful biomarker, can function as a sponge, compete with miR-205-5p, modulate KLF12 expression, and promote the development and progression of BLBC.

Comprehensive Analysis of Differentially Expressed circRNAs Reveals a Colorectal Cancer-Related ceRNA Network

The morbidity and mortality of colorectal cancer (CRC) remained to be very high worldwide. Recently, circRNAs had been revealed to have a crucial role in cancer prognosis and progression. Numerous researches have shown that RNA sequencing technology and in silico method were widely used to identify pathogenic mechanisms and uncover promising targets for diagnosis and therapy. In this study, these methods were analyzed to obtain differentially expressed circRNAs (DECs). We identified upregulated 316 circRNAs and reduced 76 circRNAs in CRC samples, in comparison with those in normal tissues. In addition, a competitive endogenous network of circRNA-miRNA-mRNA was established to predict the mechanisms of circRNAs. Bioinformatics analysis revealed that these circRNAs participated in metabolism regulation and cell cycle progression. Of note, we observed the hub genes and miRNAs in this ceRNA network were associated with the survival time in CRC. We think this study could provide potential prognostic biomarkers and targets for CRC.

Circular RNA is a popular molecule in tumors of the digestive system (Review)

Most tumors of the digestive system, including esophageal, gastric, liver and colorectal cancer, are malignant tumors that are associated with rates of high morbidity and mortality. The lack of effective methods for early diagnosis is an important cause of poor prognosis for these malignancies. Circular RNAs (circRNAs) belong to a family of endogenous, covalently closed non‑coding RNAs that are characterized as having no 5' cap structures or 3' poly‑A tails. Shortly following discovery, circRNAs were considered to be a product of mis‑splicing and have no significant biological function. However, in recent years, accumulating evidence is demonstrating that they serve key roles in tumorigenesis and have the potential to serve as diagnostic markers. The present article summarizes the biogenesis and function of circRNAs and reviews their role in seven common types of tumor of the digestive system whilst exploring their potential as tumor markers and the significant roles they can serve in the digestive system, in addition to providing a referencing point for future studies of digestive system malignancies.

circ_ARF3 regulates the pathogenesis of osteosarcoma by sponging miR-1299 to maintain CDK6 expression

Increasing evidence suggests that circular RNAs are emerging biomarkers or targets for early cancer diagnosis and treatment. However, the studies of circular RNA in osteosarcoma (OS) are limited. In this study we found that circ_ARF3 were highly expressed in osteosarcoma cell lines and tumor tissues. Knocking down circ_ARF3 greatly ceased OS cell growth, impaired cell colony formation and halted cell cycle transition from G1 to S phase. Bioinformatic analysis suggested that miR-1299 is the target of circ_ARF3. Luciferase assay and biotin labeled circ_ARF3 pull down assay confirmed their interactions in OS cells. The regulatory roles of circ_ARF3 on miR-1299 was also investigated. Further bioinformatic analysis showed that CDK6 is the target of miR-1299. Overexpressing miR-1299 in OS cells decreased CDK6 expression and arrested OS cell growth and cell cycle progression. However, the roles of miR-1299 in regulating CDK6 expression, OS cell growth and cell cycle progression were greatly impaired in the presence of circ_ARF3. In general, our study demonstrated that in the OS, highly expressed circ_ARF3 acts as a sponge of miR-1299 to inhibit miR-1299 mediated CDK6 downregulation which further promoted OS pathogenesis. circ_ARF3 could be a potential target for OS treatment in the future.

Identification and integrated analysis of hepatocellular carcinoma-related circular RNA signature

Background

Circular RNAs (circRNAs), a novel type of non-coding RNA, play a vital role in the pathogenesis and development of cancer. CircRNAs signatures may be useful as prognostic and predictive factors as well as clinical tools for evaluating disease status and prognosis. This study was carried out to explore novel circRNA signatures in hepatocellular carcinoma (HCC).

Methods

The expression profiles of circRNAs were retrieved from the Gene Expression Omnibus (GEO). The expression profiles of miRNAs and mRNAs were obtained from The Cancer Genome Atlas (TCGA) and the Genotype-Tissue Expression (GTEx) database. The results of the microarray were validated by quantitative real-time RCR (qPCR). Based on circRNA-miRNA pairs and miRNA-mRNA pairs, a competitive endogenous RNA (ceRNA) network was constructed. Functional analysis was performed via Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), gene set enrichment analysis (GSEA), and gene set variation analysis (GSVA). Furthermore, survival analysis was carried out using the Kaplan-Meier curve and the log-rank test.

Results

Differentially expressed circRNAs in HCC from GEO databases (GSE94508 and GSE97332) were screened and analyzed using the bioinformatics method. We detected a total of 26 differentially expressed circRNAs by qPCR and then selected 6 circRNAs to construct the circRNA-miRNA-mRNA networks. Through prognostic analysis, 3 target hub genes (AURKA, KIF5B, and RHOA) of circRNAs were discovered. Moreover, GSEA and GSVA were used to reveal the functions of AURKA, KIF5B, and RHOA in HCC.

Conclusions

We identified three hub genes, and our results suggest that the circHMGCS1/miR-581/AURKA, circHMGCS1/miR-892a/KIF5B, and circTMCO3/miR-577/RHOA axes may play a vital role in HCC progression.

Identification of downregulated circRNAs from tissue and plasma of patients with gastric cancer and construction of a circRNA-miRNA-mRNA network

The connection between circular RNAs (circRNAs) and gastric cancer has been reported widely in recent years. However, previous studies have focused mainly on circRNAs from gastric cancer tissue. The objectives of the present study were to detect dysregulated circRNAs from both tissue and plasma of patients with gastric cancer and to explore their potential roles in the pathogenesis of gastric cancer. Expression profiles of circRNAs were obtained from the Gene Expression Omnibus (GEO) and analyzed using the GEO2R tool to identify differential expressed circRNAs. The significance threshold was set as |log2 (fold change)| > 2 and adjusted P < .05. The microRNA (miRNA) binding sites of the differentially expressed circRNAs were predicted using the Circular RNA Interactome web tool. TargetScan and the miRNet database were used to predict the miRNA target genes. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses were performed using Database for Annotation Visualization and Integrated Discovery. Hub genes were identified and a network was constructed with Cytoscape. The overall survival rates for the selected miRNAs and messenger RNAs were evaluated by Kaplan-Meier Plotter. A total of three downregulated circRNAs (hsa_circ_0001190, hsa_circ_0036287, and hsa_circ_0048607) were identified in this study. Six miRNAs and eight hub genes met the significance criteria and were selected for further analysis. A circRNA-miRNA-hub gene network was constructed based on three circRNAs, six miRNAs, and eight hub genes. Evaluation of overall survival rates for the hub genes showed that low expression levels of GADD45A, PPP1CB, PJA2, and KLF2 were associated with poor overall survival. This study identified potential novel plasma circRNA biomarkers and provides insights into the underlying mechanisms of gastric cancer pathogenesis.