CircRNA-0008717 promotes cell proliferation, migration, and invasion by regulating miR-203/Slug in esophageal cancer cells

MicroRNAs: A novel signature in the metastasis of esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is a malignant epithelial tumor, characterized by squamous cell differentiation, it is the sixth leading cause of cancer-related deaths globally. The increased mortality rate of ESCC patients is predominantly due to the advanced stage of the disease when discovered, coupled with higher risk of metastasis, which is an exceedingly malignant characteristic of cancer, frequently leading to a high mortality rate. Unfortunately, there is currently no specific and effective marker to predict and treat metastasis in ESCC. MicroRNAs (miRNAs) are a class of small non-coding RNA molecules, approximately 22 nucleotides in length. miRNAs are vital in modulating gene expression and serve pivotal regulatory roles in the occurrence, progression, and prognosis of cancer. Here, we have examined the literature to highlight the intimate correlations between miRNAs and ESCC metastasis, and show that ESCC metastasis is predominantly regulated or regulated by genetic and epigenetic factors. This review proposes a potential role for miRNAs as diagnostic and therapeutic biomarkers for metastasis in ESCC metastasis, with the ultimate aim of reducing the mortality rate among patients with ESCC.

Association of miR-203 Expression with Prognostic Value in Patients with Esophageal Cancer: A Systematic Review and Meta-Analysis

OBJECTIVE

This study aims to investigate the association between miR-203 expression and the prognostic value in patients with esophageal cancer by the method of systematic review and meta-analysis.

METHODS

We searched PubMed, Web of Science, Embase, and Cochrane Library to collect studies on the relationship between miR-203 expression and the prognostic value of esophageal cancer up to July 2023. Stata 15.0 statistical software was used for data analysis. Hazard ratio (HR) and 95% confidence interval (CI) were used as effect sizes.

RESULTS

A total of 6 studies were included in this review, including 476 patients with esophageal cancer. The results showed that miR-203 low expression was associated with worse overall survival (OS) in patients with esophageal cancer compared with miR-203 high expression (HR = 2.80, 95%CI: 1.99 ∼ 3.93, p < 0.001). The results of Egger's (p = 0.154) and Begg's Tests (p = 0.221) indicated no obvious publication bias. Sensitivity analysis verified the robustness of the results obtained in this study.

CONCLUSION

The expression of miR-203 is significantly correlated with the prognostic value in patients with esophageal cancer. Esophageal cancer patients with high expression of miR-203 had better prognosis than those with low expression of miR-203. Due to the limited studies included in this meta-analysis, more trials are needed to confirm the conclusions of this study in the future.

circMSH3 is a potential biomarker for the diagnosis of colorectal cancer and affects the distant metastasis of colorectal cancer

Objectives

To identify the most significantly differentially expressed circular RNAs (circRNAs) in colorectal cancer (CRC) tissues in terms of their expression levels and circularity, and to analyze the relationship between their expression levels and the clinical characteristics of patients.

Methods

circRNA RNA-seq technology was used to screen differentially expressed circRNAs in CRC. Sanger sequencing was used to identify circRNA back-splice junction sites. The relative expression levels of hsa_circ_0003761 (circMSH3) in CRC tissues and cell lines were detected by quantitative real-time fluorescence PCR technology. An RNA-protein pull-down assay was used to detect protein binding to circRNAs. Dual-luciferase reporter gene vectors were constructed to verify that circRNAs bind to microRNAs.

Results

Four hundred twenty circRNAs were found to be upregulated, and 616 circRNAs were downregulated. circMSH3 was derived from the MutS homolog 3 (MSH3) gene and was formed by a loop of exons 9, 10, 11, and 12. In 110 pairs of CRC and adjacent tissues, circMSH3 expression was 4.487-fold higher in CRC tissues. circMSH3 was also highly expressed in the HT-29 and LOVO CRC cell lines. The expression level of circMSH3 was associated with distant metastasis in CRC patients (P = 0.043); the area under the curve (AUC) of circMSH3 for CRC diagnosis was 0.75, with a sensitivity and specificity of 70.9% and 66.4%, respectively. circMSH3 could bind to a variety of proteins, mainly those involved in RNA transcription, splicing, cell cycle, and cell junctions. Furthermore, circMSH3 could bind to miR-1276, miR-942-5p, and miR-409-3p.

Conclusion

circMSH3 is a potential biomarker for the diagnosis of CRC and affects the distant metastasis of CRC. Multiple RNA-binding protein binds to circMSH3, and circMSH3 binds to miR-1276, miR-942-5p, and miR-409-3p, thereby affecting the expression of circMSH3.

The Emerging Roles of Circ-ABCB10 in Cancer

Circular RNAs (circRNAs) are non-coding RNAs (ncRNAs) without 5′ caps and 3′ tails, which are formed from precursor mRNAs (pre-mRNAs) that are inversely back-spliced by exons. CircRNAs are characterized by a covalently closed circular structure and are abundantly expressed in eukaryotic cells. With the development of RNA-sequencing, it was discovered that circRNAs play important roles in the regulation of numerous human genes and are related to the occurrence, development, and prognosis of diseases. Studies in various cancers have revealed that circRNAs have both positive and negative effects on the occurrence and development of tumors. Circ-ABCB10, a circular RNA originating from exons of ABCB10 located on chromosome 1q42, has been proven to play an important role in different types of cancers. Here, we report the primary findings of recent research studies by many contributors about the roles of circ-ABCB10 in cancer and clearly formulate its influence and functions in different aspects of cancer biology, which gives us a broad picture of circ-ABCB10. Thus, this study aimed to generalize the roles of circ-ABCB10 in the diagnosis and treatment of different types of tumors and its related miRNA genes. In this way, we wish to provide a sufficient understanding and assess the future development direction of the research on circ-ABCB10.

Integral Analyses of Competing Endogenous RNA Mechanisms and DNA Methylation Reveal Regulatory Mechanisms in Osteosarcoma

Background: Osteosarcoma (OS) is the most common primary malignant bone tumour in children and adolescents, with rapid growth, frequent metastasis, and a poor prognosis, but its pathogenesis has not been fully elucidated. Exploring the pathogenesis of OS is of great significance for improving diagnoses and finding new therapeutic targets.

Methods: Differentially expressed circRNAs (DECs), miRNAs (DEMs), methylated DNA sites (DMSs), and mRNAs (DEGs) were identified between OS and control cell lines. GSEA of DEGs and functional enrichment analysis of methylated DEGs were carried out to further identify potential biological processes. Online tools were used to predict the miRNA binding sites of DECs and the mRNA binding sites of DEMs, and then construct a circRNA-miRNA-mRNA network. Next, an analysis of the interaction between methylated DEGs was performed with a protein-protein interaction (PPI) network, and hub gene identification and survival analysis were carried out. The expression pattern of circRNA-miRNA-mRNA was validated by real-time PCR.

Results: GSEA and functional enrichment analysis indicated that DEGs and methylated DEGs are involved in important biological processes in cancer. Hsa_circ_0001753/has_miR_760/CD74 network was constructed and validated in cell lines. Low expression levels of CD74 are associated with poor overall survival times and show good diagnostic ability.

Conclusion: Methylated DEGs may be involved in the development of OS, and the hsa_circ_0001753/has_miR_760/CD74 network may serve as a target for the early diagnosis of and targeted therapy for OS.

A Novel Age-Related Circular RNA Circ-ATXN2 Inhibits Proliferation, Promotes Cell Death and Adipogenesis in Rat Adipose Tissue-Derived Stromal Cells

Adipose tissue-derived stromal cells are promising candidates investigating the stem cell-related treatment. However, their proportion and utility in the human body decline with time, rendering stem cells incompetent to complete repair processes in vivo. The involvement of circRNAs in the aging process is poorly understood. Rat subcutaneous adipose tissue from 10-week-old and 27-month-old rats were used for hematoxylin and eosin (H and E) staining, TUNEL staining, and circRNA sequencing. Rat adipose tissue-derived stromal cells were cultured and overexpressed with circ-ATXN2. Proliferation was examined using xCELLigence real-time cell analysis, EdU staining, and cell cycle assay. Apoptosis was induced by CoCl2 and examined using flow cytometry. RT-PCR assay and Oil Red O staining were used to measure adipogenesis at 48 h and 14 days, respectively. H and E staining showed that the diameter of adipocytes increased; however, the number of cells decreased in old rats. TUNEL staining showed that the proportion of apoptotic cells was increased in old rats. A total of 4,860 and 4,952 circRNAs was detected in young and old rats, respectively. Among them, 67 circRNAs exhibited divergent expression between the two groups (fold change ≥2, p ≤ 0.05), of which 33 were upregulated (49.3%) and 34 were downregulated (50.7%). The proliferation of circ-ATXN2-overexpressing cells decreased significantly in vitro, which was further validated by xCELLigence real-time cell analysis, EdU staining, and cell cycle assay. Overexpression of circ-ATXN2 significantly increased the total apoptotic rate from 5.78 ± 0.46% to 11.97 ± 1.61%, early apoptotic rate from 1.76 ± 0.22% to 5.50 ± 0.66%, and late apoptosis rate from 4.02 ± 0.25% to 6.47 ± 1.06% in adipose tissue-derived stromal cells. Furthermore, in circ-ATXN2-overexpressing cells, RT-PCR assay revealed that the expression levels of adipose differentiation-related genes PPARγ and CEBP/α were increased and the Oil Red O staining assay showed more lipid droplets. Our study revealed the expression profile of circRNAs in the adipose tissue of old rats. We found a novel age-related circular RNA—circ-ATXN2—that inhibits proliferation and promotes cell death and adipogenesis in rat adipose tissue-derived stromal cells.

Circ-SFMBT2 drives the malignant phenotypes of esophageal cancer by the miR-107-dependent regulation of SLC1A5

Background

Increasing studies focused on the regulatory roles of circular RNAs (circRNAs) in diverse cancers. This study was to evaluate the function and mechanism of circRNA Scm-like with four malignant brain tumor domains 2 (circ-SFMBT2) in esophageal cancer (EC).

Methods

The circ-SFMBT2, microRNA-107 (miR-107) and solute-linked carrier family A1 member 5 (SLC1A5) levels were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). Cell proliferation was evaluated by 3-(4, 5-dimethylthiazol-2-y1)-2, 5-diphenyl tetrazolium bromide (MTT) assay, colony formation assay and EdU assay. Cell apoptosis and invasion were detected by flow cytometry and transwell assay. Glutamine metabolism was assessed by the corresponding kits for glutamine consumption, α-ketoglutarate production and glutamate production. Western blot was used for protein quantification. The binding analysis was performed using dual-luciferase reporter assay, RNA immunoprecipitation (RIP) and pull-down assays. The functional research of circ-SFMBT2 in vivo was performed by xenograft tumor assay. Exosomes were identified by morphological observation and protein detection.

Results

Circ-SFMBT2 was overexpressed in EC samples and cells. Circ-SFMBT2 downregulation inhibited EC cell proliferation, invasion and glutamine metabolism. Circ-SFMBT2 targeted miR-107 and the regulation of circ-SFMBT2 was achieved by sponging miR-107. SLC1A5 was a target of miR-107, and it worked as an oncogene in EC cells. MiR-107 retarded the EC progression by downregulating SLC1A5. Circ-SFMBT2 could affect the SLC1A5 expression by targeting miR-107. Circ-SFMBT2 regulated EC progression in vivo by miR-107/SLC1A5 axis. Circ-SFMBT2 was transferred by exosomes in EC cells.

Conclusion

These results suggested that circ-SFMBT2 upregulated the SLC1A5 expression to promote the malignant development of EC by serving as a miR-107 sponge.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02156-8.

Circular RNA hsa_circ_0000277 sequesters miR-4766-5p to upregulate LAMA1 and promote esophageal carcinoma progression

Growing evidence has indicated that circular RNAs (circRNAs) play a pivotal role as functional RNAs in diverse cancers. However, most circRNAs involved in esophageal squamous cell carcinoma (ESCC) remain undefined, and the underlying molecular mechanisms mediated by circRNAs are largely unclear. Here, we screened human circRNA expression profiles in ESCC tissues and found significantly increased expression of hsa_circ_0000277 (termed circPDE3B) in ESCC tissues and cell lines compared to the normal controls. Moreover, higher circPDE3B expression in patients with ESCC was correlated with advanced tumor-node-metastasis (TNM) stage and dismal prognosis. Functional experiments demonstrated that circPDE3B promoted the tumorigenesis and metastasis of ESCC cells in vitro and in vivo. Mechanistically, bioinformatics analysis, a dual-luciferase reporter assay, and anti-AGO2 RNA immunoprecipitation showed that circPDE3B could act as a competing endogenous RNA (ceRNA) by harboring miR-4766-5p to eliminate the inhibitory effect on the target gene laminin α1 (LAMA1). In addition, LAMA1 was significantly upregulated in ESCC tissues and was positively associated with the aggressive oncogenic phenotype. More importantly, rescue experiments revealed that the oncogenic role of circPDE3B in ESCC is partly dependent on the miR-4766-5p/LAMA1 axis. Furthermore, bioinformatics analysis combined with validation experiments showed that epithelial-mesenchymal transition (EMT) activation was involved in the oncogenic functions of the circPDE3B-miR-4766-5p/LAMA1 axis in ESCC. Taken together, we demonstrate for the first time that the circPDE3B/miR-4766-5p/LAMA1 axis functions as an oncogenic factor in promoting ESCC cell proliferation, migration, and invasion by inducing EMT, implying its potential prognostic and therapeutic significance in ESCC.

Circular RNA circ_ABCB10 in cancer

Circular RNA (circRNA), a newly discovered type of endogenous noncoding RNA, has become a focus and hotspot in biological research in recent years. It exists widely and possesses a stable structure, is highly conserved and has cell-specific expression. circRNA is associated with disease occurence in general and cancer specifically due to its role in cell differentiation, proliferation, invasion and metastasis. Recently, circ_ABCB10, an increasingly studied member of the annular RNA family, has attracted considerable attention due to the fact that its expression is upregulated in various tumors, ie, esophageal cancer, breast cancer, lung cancer, and glioma, and may be of prognostic value. Molecular regulation and mechanism of circ_ABCB10 action in cancer are reviewed and its potential as a molecular marker and novel target for diagnosis and treatment are explored..