Circular RNA expression profiling identifies specific circular RNAs in tongue squamous cell carcinoma

Hsa_circRNA_0084043 promoting tumorigenesis in glioma through miR-577 sponging

Circular RNAs (circRNAs) are important non-coding RNAs (ncRNAs) involved in the development of multiple human diseases, especially cancers. circRNA_0084043 is significantly involved in the progression of melanoma. However, whether circRNA_0084043 is associated with glioma remains unknown. In this study, the upregulation of circRNA_0084043 in glioma and the association between circRNA_0084043 and glioma grade were identified. Our results showed that circRNA_0084043 is significantly involved in the proliferative, migratory, and invasive capacities of glioma cells. The results obtained from starBase, luciferase reporter assays, RNA immunoprecipitation assays, and RNA pull-down assays demonstrated that circRNA_0084043 acts as a direct sponge for miR-577. TargetScan algorithm was used to identify potential miR-577 targets, it was found that sorting nexin 5 (SNX5) is a candidate bound to miR-577. Finally, cell experiments testified that circRNA_0084043 enhanced growth, migration and invasion of glioma through the regulation of miR-577-mediated SNX5. Taken together, we concluded that circRNA_0084043 in the miR-577/SNX5 axis can be used as a candidate target for glioma therapy.

Noncoding RNAs in oral cancer

Oral cancer (OC) is the most prevalent subtype of cancer arising in the head and neck region. OC risk is mainly attributed to behavioral risk factors such as exposure to tobacco and excessive alcohol consumption, and a lesser extent to viral infections such as human papillomaviruses and Epstein-Barr viruses. In addition to these acquired risk factors, heritable genetic factors have shown to be associated with OC risk. Despite the high incidence, biomarkers for OC diagnosis are lacking and consequently, patients are often diagnosed in advanced stages. This delay in diagnosis is reflected by poor overall outcomes of OC patients, where 5-year overall survival is around 50%. Among the biomarkers proposed for cancer detection, noncoding RNA (ncRNA) can be considered as one of the most promising categories of biomarkers due to their role in virtually all cellular processes. Similar to other cancer types, changes in expressions of ncRNAs have been reported in OC and a number of ncRNAs have diagnostic, prognostic, and therapeutic potential. Moreover, some ncRNAs are capable of regulating gene expression by various mechanisms. Therefore, elucidating the current literature on the four main types of ncRNAs namely, microRNA, lncRNA, snoRNA, piwi-RNA, and circular RNA in the context of OC pathogenesis is timely and would enable further improvements and innovations in diagnosis, prognosis, and treatment of OC. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA in Disease and Development > RNA in Development.

Hsa_circ_0081069 facilitates tongue squamous cell carcinoma progression by modulating MAP2K4 expression via miR-634

It has been demonstrated that circular RNA (circRNA) is involved in the progression of tongue squamous cell carcinoma (TSCC). The aim of this study was to investigate the intrinsic mechanism of circ_0081069 in TSCC progression. The expression levels of circ_00081069, miR-634, and mitogen-activated protein kinase kinase 4 (MAP2K4) in TSCC tissues and cells were detected by quantitative real-time PCR (qRT-PCR). Cell counting kit 8 assay, Edu assay, and flow cytometry assay were used to detect cell proliferation and cell cycle distribution. Transwell assay was used to detect cell migration and invasion abilities. Western blot analysis was performed to detect the protein expression. Dual-luciferase reporter assay was used to detect the targeting relationships of circ_0081069, miR-634 and MAP2K4. Immunohistochemical staining was used to measure MAP2K4-positive cells in tissues. The effect of circ_0081069 silencing on tumor formation in TSCC in vivo was explored by xenograft tumor assay. Circ_0081069 was highly expressed in TSCC tissues and cells. Silencing of circ_0081069 inhibited cell proliferation, cell cycle progress, cell migration and invasion in vitro, as well as hindered tumor growth in vivo. Mechanistically, circ_0081069 targeted miR-634 to negatively regulate miR-634 expression, and inhibition of miR-634 was able to weaken the inhibitory effect of circ_0081069 knockdown on proliferation, migration, and invasion of TSCC cells. MiR-634 targeted MAP2K4 and negatively regulated MAP2K4 expression, and overexpression of miR-634 inhibited TSCC cell proliferation, migration, and invasion, while co-overexpression of MAP2K4 was able to reverse the effects of miR-634 in TSCC cells. Circ_0081069 is involved in the regulation of proliferation, cycle progress, migration, and invasion of TSCC cells through the miR-634/MAP2K4 axis and has the potential to serve as a diagnostic biomarker and therapeutic target.

Expression profile and bioinformatics analysis of circular RNAs in tongue squamous cell carcinoma

OBJECTIVE

This study was designed to identify the role of circRNAs in tongue squamous cell carcinoma (TSCC) and discover novel circRNAs as potential diagnostic or therapeutic targets for TSCC.

RESULTS

The circRNA expression profiles in TSCC were evaluated by high-throughput sequencing in 6 TSCC patients. Our data showed that 69 circRNAs were downregulated and 208 were upregulated significantly (fold change ≥2.0; p < 0.05). GO and KEGG analysis demonstrated that the parental genes of differentially expressed circRNAs were potentially implicated in TSCC pathogenesis. After bioinformatics analysis, 4 circRNAs (hsa_circ_0005035, hsa_circ_0002360, hsa_circ_0066251, and hsa_circ_0003161) were selected and successfully validated by quantitative reverse-transcription polymerase chain reaction (qRT-PCR) in 40 patients and 3 TSCC cell lines. The establishment and analysis of the circRNA-miRNA-mRNA network revealed the potential function and mechanism of these candidate circRNAs.

CONCLUSION

Our study provided a comprehensive circRNAs expression profile of TSCC by RNA-seq and discovered 4 novel circRNAs with potential great diagnostic and therapeutic value. These findings provide new insights into the development of potential biomarkers and targets for TSCC treatment.

Circ_0044556 Promotes the Progression of Colorectal Cancer via the miR-665-Dependent Expression Regulation of Diaphanous Homolog 1

BACKGROUND

Cancer progression can be regulated by noncoding circular RNAs. A recent study has indicated that circ_0044556 facilitated the progression of colorectal cancer.

AIM

This research was performed to explore the regulatory mechanism of circ_0044556 in CRC.

METHODS

Circ_0044556, miR-665 and Diaphanous Homolog 1 levels were detected by the quantitative real-time polymerase chain reaction. Cell proliferation analysis was performed by cell counting kit-8 assay and Edu assay. Cell cycle progression was assessed using flow cytometry. The protein examination was conducted using western blot. Transwell assay was used to analyze cell migration and invasion. Dual-luciferase reporter assay was performed to validate the interaction between targets. In vivo research was implemented by xenograft tumor assay.

RESULTS

Circ_0044556 was upregulated in colorectal cancer samples and cells. Silencing circ_0044556 inhibited cell proliferation, cell cycle progression, migration, invasion, and epithelial-mesenchymal transition in CRC cells. Circ_0044556 could directly target miR-665 and the function of circ_0044556 was associated with the regulation of miR-665. In addition, Diaphanous Homolog 1 was a target gene for miR-665 and the anti-tumor role of miR-665 in colorectal cancer was dependent on the downregulation of Diaphanous Homolog 1. Diaphanous Homolog 1 level was regulated by circ_0044556 via sponging miR-665 in CRC cells. In vivo assay suggested that circ_0044556 promoted CRC tumor growth by regulating the miR-665 and Diaphanous Homolog 1 levels.

CONCLUSION

Our findings manifested that circ_0044556 functioned as an oncogenic circRNA in colorectal cancer by mediating the miR-665/Diaphanous Homolog 1 axis, elucidating the molecular mechanism of circ_0044556 in CRC progression.

CircCOL1A2 Sponges MiR-1286 to Promote Cell Invasion and Migration of Gastric Cancer by Elevating Expression of USP10 to Downregulate RFC2 Ubiquitination Level

Gastric cancers (GC) are generally malignant tumors, occurring with high incidence and threatening public health around the world. Circular RNAs (circRNAs) play crucial roles in modulating various cancers, including GC. However, the functions of circRNAs and their regulatory mechanism in colorectal cancer (CRC) remain largely unknown. This study focuses on both the role of circCOL1A2 in CRC progression as well as its downstream molecular mechanism. Quantitative polymerase chain reaction (qPCR) and western blot were adopted for gene expression analysis. Functional experiments were performed to study the biological functions. Fluorescence in situ hybridization (FISH) and subcellular fraction assays were employed to detect the subcellular distribution. Luciferase reporter, RNA-binding protein immunoprecipitation (RIP), co-immunoprecipitation (Co-IP), RNA pull-down, and immunofluorescence (IF) and immunoprecipitation (IP) assays were used to explore the underlying mechanisms. Our results found circCOL1A2 to be not only upregulated in GC cells, but that it also propels the migration and invasion of GC cells. CircCOL1A2 functions as a competing endogenous RNA (ceRNA) by sequestering microRNA-1286 (miR-1286) to modulate ubiquitin-specific peptidase 10 (USP10), which in turn spurs the migration and invasion of GC cells by regulating RFC2. In sum, CircCOL1A2 sponges miR-1286 to promote cell invasion and migration of GC by elevating the expression of USP10 to downregulate the level of RFC2 ubiquitination. Our study offers a potential novel target for the early diagnosis and treatment of GC.

Identification of circRNA-miRNA-Immune-Related mRNA Regulatory Network in Gastric Cancer

The pathogenesis of gastric cancer (GC) is still not fully understood. We aimed to find the potential regulatory network for ceRNA (circRNA–miRNA–immune-related mRNA) to uncover the pathological molecular mechanisms of GC. The expression profiles of circRNA, miRNA, and mRNA in gastric tissue from GC patients were downloaded from the Gene Expression Omnibus (GEO) datasets. Differentially expressed circRNAs, miRNAs, and immune-related mRNAs were filtered, followed by the construction of the ceRNA (circRNA–miRNA–immune-related mRNA) network. Functional annotation and protein–protein interaction (PPI) analysis of immune-related mRNAs in the network were performed. Expression validation of circRNAs and immune-related mRNAs was performed in the new GEO and TCGA datasets and in-vitro experiment. A total of 144 differentially expressed circRNAs, 216 differentially expressed miRNAs, and 2,392 differentially expressed mRNAs were identified in GC. Some regulatory pairs of circRNA–miRNA–immune-related mRNA were obtained, including hsa_circ_0050102–hsa-miR-4537–NRAS–Tgd cells, hsa_circ_0001013–hsa-miR-485-3p–MAP2K1–Tgd cells, hsa_circ_0003763–hsa-miR-145-5p–FGF10–StromaScore, hsa_circ_0001789–hsa-miR-1269b–MET–adipocytes, hsa_circ_0040573–hsa-miR-3686–RAC1–Tgd cells, and hsa_circ_0006089–hsa-miR-5584-3p–LYN–neurons. Interestingly, FGF10, MET, NRAS, RAC1, MAP2K1, and LYN had potential diagnostic value for GC patients. In the KEGG analysis, some signaling pathways were identified, such as Rap1 and Ras signaling pathways (involved NRAS and FGF10), Fc gamma R-mediated phagocytosis and cAMP signaling pathway (involved RAC1), proteoglycans in cancer (involved MET), T-cell receptor signaling pathway (involved MAP2K1), and chemokine signaling pathway (involved LYN). The expression validation of hsa_circ_0003763, hsa_circ_0004928, hsa_circ_0040573, FGF10, MET, NRAS, RAC1, MAP2K1, and LYN was consistent with the integrated analysis. In conclusion, the identified ceRNA (circRNA–miRNA–immune-related mRNA) regulatory network may be associated with the development of GC.

Oncogenic circDHTKD1 promotes tumor growth and metastasis of oral squamous cell carcinoma in vitro and in vivo via upregulating miR-326-mediated GAB1

Circular RNAs (circRNAs) have been extensively elucidated with regard to their significant implications in oral squamous cell carcinoma (OSCC). This study performed the functional investigation of circRNA dehydrogenase E1 and transketolase domain containing 1 (circDHTKD1) in OSCC. RNA expression levels of different molecules were measured via quantitative real-time polymerase chain reaction (qRT-PCR). Cellular behaviors were detected by 3-(4, 5-dimethylthiazol-2-y1)-2,5-diphenyl tetrazolium bromide (MTT) for cell viability, colony formation assay for clonal capacity, flow cytometry for cell apoptosis, wound healing assay for migration, and transwell assay for migration/invasion. Western blot was used for analyzing protein expression. RNA pull-down and dual-luciferase reporter assays were applied to assess the binding between targets. A xenograft tumor model was established in nude mice for in vivo experiments. Our expression analysis revealed that circDHTKD1 was upregulated in OSCC tissues and cells. circDHTKD1 knockdown was shown to impede OSCC cell growth and metastasis but motivate apoptosis. Additionally, circDHTKD1 served as a microRNA-326 (miR-326) sponge and the function of circDHTKD1 was achieved by sponging miR-326 in OSCC cells. Also, miR-326 inhibited OSCC development via targeting GRB2-associated-binding protein 1 (GAB1). circDHTKD1 could sponge miR-326 to alter GAB1 expression. Furthermore, circDHTKD1 contributed to OSCC progression in vivo via the miR-326/GAB1 axis. These data disclosed a specific circDHTKD1/miR-326/GAB1 signal axis in governing the malignant progression of OSCC, showing the considerable possibility of circDHTKD1 as a predictive and therapeutic target for clinical diagnosis and treatment of OSCC.

LncRNA NOP14-AS1 Promotes Tongue Squamous Cell Carcinoma Progression by Targeting MicroRNA-665/HMGB3 Axis

Purpose

The expression profile, clinical effects, and detailed roles of NOP14 antisense RNA 1 (NOP14-AS1) in tongue squamous cell carcinoma (TSCC) remain ambiguous and need to be further explored. Thus, this work was initiated to offer further solid evidence regarding the expression and roles of NOP14-AS1 in TSCC. Furthermore, additional efforts were exerted to reveal the molecular events by which NOP14-AS1 affects the malignant behaviours of TSCC.

Methods

NOP14-AS1 expression was detected in TSCC tissues and cell lines using quantitative reverse transcription-polymerase chain reaction. Cell Counting Kit-8 assay, flow cytometric analysis, Transwell migration and invasion assays, and xenograft tumor model analysis were performed to assess the malignant biological behaviors of TSCC cells after NOP14-AS1 depletion. Mechanistic studies were performed using bioinformatics analysis, luciferase reporter assay, RNA immunoprecipitation, and rescue experiments.

Results

NOP14-AS1 upregulation was identified in TSCC tissues and cell lines. Patients with TSCC exhibiting a high NOP14-AS1 expression faced shorter overall survival than those with a low NOP14-AS1 expression. Functionally, NOP14-AS1 depletion facilitated apoptosis and impeded cell proliferation, migration, and invasion in TSCC. In vivo, the growth of TSCC cells was hindered by NOP14-AS1 depletion. Mechanically, NOP14-AS1 functioned as a competing endogenous RNA by sponging microRNA-665 (miR-665), thereby overexpressing the target high mobility group box 3 (HMGB3) of miR-665. Lastly, rescue experiments confirmed that the introduction of HMGB3 overexpression plasmid or miR-665 inhibitor could abrogate the inhibition of aggressive phenotypes triggered by NOP14-AS1 knockdown.

Conclusion

NOP14-AS1 executed pro-oncogenic activities in TSCC cells by targeting the miR-665/HMGB3 axis. The NOP14-AS1/miR-665/HMGB pathway may be a valuable prognostic indicator and therapeutic target for preventing TSCC.

The Role of circRNAs in Human Papillomavirus (HPV)-Associated Cancers

Circular RNAs (circRNAs) are a new class of "non-coding RNAs" that originate from non-sequential back-splicing of exons and/or introns of precursor messenger RNAs (pre-mRNAs). These molecules are generally produced at low levels in a cell-type-specific manner in mammalian tissues, but due to their circular conformation they are unaffected by the cell mRNA decay machinery. circRNAs can sponge multiple microRNAs or RNA-binding proteins and play a crucial role in the regulation of gene expression and protein translation. Many circRNAs have been shown to be aberrantly expressed in several cancer types, and to sustain specific oncogenic processes. Particularly, in virus-associated malignancies such as human papillomavirus (HPV)-associated anogenital carcinoma and oropharyngeal and oral cancers, circRNAs have been shown to be involved in tumorigenesis and cancer progression, as well as in drug resistance, and some are useful diagnostic and prognostic markers. HPV-derived circRNAs, encompassing the HPV E7 oncogene, have been shown to be expressed and to serve as transcript for synthesis of the E7 oncoprotein, thus reinforcing the virus oncogenic activity in HPV-associated cancers. In this review, we summarize research advances in the biogenesis of cell and viral circRNAs, their features and functions in the pathophysiology of HPV-associated tumors, and their importance as diagnostic, prognostic, and therapeutic targets in anogenital and oropharyngeal and oral cancers.

Circ_0000003 regulates glutamine metabolism and tumor progression of tongue squamous cell carcinoma via the miR‑330‑3p/GLS axis

Various circular RNAs (circRNAs) have been shown to exert vital functions in tongue squamous cell carcinoma (TSCC). However, their roles in TSCC progression remain to be elucidated. This research aimed to investigate the role and mechanism of hsa_circ_0000003 (circ_0000003) in TSCC progression. Here, we found that circ_0000003 expression was upregulated in TSCC tissues and cell lines, and high circ_0000003 expression was correlated with advanced TNM stage, increased tumor size and poor patient survival. Circ_0000003 was revealed to facilitate cell proliferation, migration and invasion of TSCC cells. Mechanistically, we found that circ_0000003 acted as a competing endogenous RNA (ceRNA) that sponged miR‑330‑3p, thereby elevating glutaminase (GLS) expression. Accordingly, cell invasion, migration, glutamine consumption, α‑ketoglutarate (α‑KG) production and ATP production were significantly decreased by circ_0000003 knockdown in TSCC cells, and these effects were reversed by miR‑330‑3p inhibition. In conclusion, circ_0000003 facilitates TSCC cell proliferation, migration, invasion and glutamine catabolism by regulating the miR‑330‑3p/GLS pathway.

Hsa_circ_0043265 Restrains Cell Proliferation, Migration and Invasion of Tongue Squamous Cell Carcinoma via Targeting the miR-1243/SALL1 Axis

Increasing evidence has displayed critical roles of circular RNAs (circRNAs) in tongue squamous cell carcinoma (TSCC). Hsa_circ_0043265 (circ_0043265) has been identified as a tumor suppressor in various tumors. Nevertheless, the critical roles of circ_0043265 in the initiation and progression of TSCC are yet to be fully elucidated. In our study, RNA and protein expressions were detected via qRT-PCR and Western blot. Cell proliferation, migration and invasion were evaluated via CCK-8 and transwell assays. The interactions between circ_0043265, miR-1243 and SALL1 were analyzed via bioinformatics analyses, RNA pull-down and luciferase assays, respectively. The current study demonstrated that circ_0043265 expression was downmodulated in TSCC tissues and cell lines (SCC25, SCC15, SCC9 and Cal27). Functionally, circ_0043265 overexpression led to an attenuation of cell proliferation, migration and invasion of SCC25 and Cal27 cells. Mechanistically, circ_0043265 acted as a competing endogenous RNA (ceRNA) via competitively sponging miR-1243, and restoration of miR-1243 rescued the inhibitory effects of circ_0043265 on cell proliferation, migration and invasion of SCC25 and Cal27 cells. Finally, it was observed that spalt like transcription factor 1 (SALL1), a potential target of miR-1243, was positively modulated via circ_0043265 in SCC25 and Cal27 cells, and SALL1 knockdown reversed the inhibitory effects of circ_0043265 on SCC25 and Cal27 cells. Collectively, the current study demonstrated that circ_0043265 was downmodulated in TSCC and was identified as a ceRNA that restrained the cell proliferation, migration and invasion of SCC25 and Cal27 cells via modulating the miR-1243/SALL1 axis.

Exosomal cargoes in OSCC: current findings and potential functions

Oral squamous cell carcinoma (OSCC) is the most prevalent malignancy in head and neck cancer, with high recurrence and mortality. Early diagnosis and efficient therapeutic strategies are vital for the treatment of OSCC patients. Exosomes can be isolated from a broad range of different cell types, implicating them as important factors in the regulation of human physiological and pathological processes. Due to their abundant cargo including proteins, lipids, and nucleic acids, exosomes have played a valuable diagnostic and therapeutic role across multiple diseases, including cancer. In this review, we summarize recent findings concerning the content within and participation of exosomes relating to OSCC and their roles in tumorigenesis, proliferation, migration, invasion, metastasis, and chemoresistance. We conclude this review by looking ahead to their potential utility in providing new methods for treating OSCC to inspire further research in this field.