Circular RNA circMDM2 accelerates the glycolysis of oral squamous cell carcinoma by targeting miR-532-3p/HK2

The potential role of circular RNAs in regulating p53 in different types of cancers

P53 tumor suppressor is a major regulator of various cellular processes and functions. It has been reported that mutation or inactivation of p53 plays a crucial role in tumorigenesis in different types of cancers. Circular RNAs (circRNAs) are single-stranded non-coding RNAs that have significant post-transcriptional effects on the regulation of gene expression in various ways. These molecules can alter the expression and function of multiple genes and proteins. In the present study, we aimed to review circRNAs that regulate the expression, function, and stability of p53 and the possible interactions between these molecules and p53. Considering the importance of p53 in cancer and the network between p53 and circRNAs, future clinical trials targeting these circRNAs as therapeutic agents deserve worthy of attention.

MicroRNA-532 as a probable diagnostic and therapeutic marker in cancer patients

The high mortality rate in cancer patients is always one of the main challenges of the health systems globally. Several factors are involved in the high rate of cancer related mortality, including late diagnosis and drug resistance. Cancer is mainly diagnosed in the advanced stages of tumor progression that causes the failure of therapeutic strategies and increases the death rate in these patients. Therefore, assessment of the molecular mechanisms associated with the occurrence of cancer can be effective to introduce early tumor diagnostic markers. MicroRNAs (miRNAs) as the stable non-coding RNAs in the biological body fluids are involved in regulation of cell proliferation, migration, and apoptosis. MiR-532 deregulation has been reported in different tumor types. Therefore, in the present review we discussed the role of miR-532 during tumor growth. It has been shown that miR-532 has mainly a tumor suppressor role through the regulation of transcription factors, chemokines, and signaling pathways such as NF-kB, MAPK, PI3K/AKT, and WNT. In addition to the independent role of miR-532 in regulation of cellular processes, it also functions as a mediator of lncRNAs and circRNAs. Therefore, miR-532 can be considered as a non-invasive diagnostic/prognostic marker as well as a therapeutic target in cancer patients.

AKR1B10 accelerates glycolysis through binding HK2 to promote the malignant progression of oral squamous cell carcinoma

BACKGROUND

Oral squamous cell carcinoma (OSCC) remains a rampant oral cavity neoplasm with high degree of aggressiveness. Aldo-keto reductase 1B10 (AKR1B10) that is an oxidoreductase dependent on nicotinamide adenine dinucleotide phosphate (NADPH) has been introduced to possess prognostic potential in OSCC. The present work was focused on specifying the involvement of AKR1B10 in the process of OSCC and its latent functional mechanism.

METHODS

AKR1B10 expression in OSCC tissues and cells were detected by RT-qPCR and Western blot analysis. CCK-8 method, EdU staining, wound healing and transwell assays respectively assayed cell viability, proliferation, migration and invasion. Immunofluorescence staining and Western blot evaluated epithelial mesenchymal transition (EMT). Adenosine triphosphate (ATP) contents, glucose consumption and extracellular acidification rate (ECAR) were measured by relevant commercially available kits and Seahorse XF96 Glycolysis Analyzer, severally. The expressions of proteins associated with metastasis and glycolysis were examined with Western blot. Co-IP assay confirmed the binding between AKR1B10 and hexokinase 2 (HK2).

RESULTS

It was observed that AKR1B10 expression was increased in OSCC tissues and cells. After AKR1B10 was knocked down, the proliferation, migration, invasion and EMT of OSCC cells were all hampered. Additionally, AKR1B10 silencing suppressed glycolysis and bound to HK2 in OSCC cells. Up-regulation of HK2 partially abolished the hampered glycolysis, proliferation, migration, invasion and EMT of AKR1B10-silenced OSCC cells.

CONCLUSION

To sum up, AKR1B10 could bind to HK2 to accelerate glycolysis, thereby facilitating the proliferation, migration, invasion and EMT of OSCC cells.

RNA-Based Liquid Biopsy in Head and Neck Cancer

Head and neck cancer (HNC) is a prevalent and diverse group of malignancies with substantial morbidity and mortality rates. Early detection and monitoring of HNC are crucial for improving patient outcomes. Liquid biopsy, a non-invasive diagnostic approach, has emerged as a promising tool for cancer detection and monitoring. In this article, we review the application of RNA-based liquid biopsy in HNC. Various types of RNA, including messenger RNA (mRNA), microRNA (miRNA), long non-coding RNA (lncRNA), small nuclear RNA (snRNA), small nucleolar RNA (snoRNA), circular RNA (circRNA) and PIWI-interacting RNA (piRNA), are explored as potential biomarkers in HNC liquid-based diagnostics. The roles of RNAs in HNC diagnosis, metastasis, tumor resistance to radio and chemotherapy, and overall prognosis are discussed. RNA-based liquid biopsy holds great promise for the early detection, prognosis, and personalized treatment of HNC. Further research and validation are necessary to translate these findings into clinical practice and improve patient outcomes.

Circular RNA Expression Signatures Provide Promising Diagnostic and Therapeutic Biomarkers for Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL) is a known hematologic malignancy associated with a growing incidence and post-treatment relapse. Hence, finding a reliable diagnostic biomarker for CLL is crucial. Circular RNAs (circRNAs) represent a new class of RNA involved in many biological processes and diseases. This study aimed to define a circRNA-based panel for the early diagnosis of CLL. To this point, the list of the most deregulated circRNAs in CLL cell models was retrieved using bioinformatic algorithms and applied to the verified CLL patients' online datasets as the training cohort (n = 100). The diagnostic performance of potential biomarkers represented in individual and discriminating panels, was then analyzed between CLL Binet stages and validated in individual sample sets I (n = 220) and II (n = 251). We also estimated the 5-year overall survival (OS), introduced the cancer-related signaling pathways regulated by the announced circRNAs, and provided a list of possible therapeutic compounds to control the CLL. These findings show that the detected circRNA biomarkers exhibit better predictive performance compared to current validated clinical risk scales, and are applicable for the early detection and treatment of CLL.

Circular hsa_circ_0020377 regulates KLF7 by targeting miR-194-5p to facilitate tumor cell malignant behaviors and glycolysis in oral squamous cell carcinoma progression

Oral squamous cell carcinoma (OSCC) is a common malignant tumor with high recurrence, metastasis rates, and poor prognosis. Numerous studies discover that circular RNA (circRNA) is closely associated with OSCC progression. Hsa_circ_0020377 has been aberrantly expressed in OSCC, but its role in tumor growth and metastasis remains largely unclear. Hsa_circ_0020377, microRNA-194-5p (miR-194-5p), and Krüppel-like factor 7 (KLF7) contents were determined by real-time quantitative polymerase chain reaction (RT-qPCR). Cell proliferative, cycle progression migration, and invasion were measured using 5-ethynyl-2'-deoxyuridine (EdU), Cell Counting Kit-8 (CCK-8), flow cytometry, wound healing, and Transwell assays. The glycolysis level was detected via specific kits. Cyclin D1, E-cadherin, hexokinase 2 (HK2), and KLF7 protein levels were detected via western blot. Using predicting bioinformatics software, the binding between miR-194-5p and hsa_circ_0020377 or KLF7 was verified using a dual-luciferase reporter and RNA Immunoprecipitation (RIP). Beyond that, a xenograft tumor model was used to analyze the role of hsa_circ_0020377 on tumor cell growth in vivo. Increased hsa_circ_0020377 and KLF7 and reduced miR-194-5p were found in OSCC tissues and cell lines. Loss-of-function experiments proved that hsa_circ_0020377 depletion might block OSCC cell proliferation, cycle progression, migration, invasion, and glycolysis in vitro. In xenograft mouse models, hsa_circ_0020377 silencing might suppress tumor growth. In addition, mechanism research suggested that hsa_circ_0020377 could bind with miR-194-5p and enhance its target gene (KLF7), thereby affecting OSCC development. These results broaden our insights regarding the regulation of OSCC progression via circRNA and act as a reference for future clinical studies in OSCC diagnosis and treatment.

CircMAT2B Induced by TEAD1 Aggravates the Warburg Effect and Tumorigenesis of Oral Squamous Cell Carcinoma through the miR-942-5p/HSPD1 Axis

Oral squamous cell carcinoma (OSCC) is one of the most lethal cancers worldwide. The high morbidity and mortality of OSCC are a great burden to global health-care systems. Therefore it is important to understand the underlying molecular mechanisms of OSCC initiation and progression. This study aimed to investigate the role of circMAT2B in OSCC progression and its molecular mechanisms. First, the expression and circularization of circMAT2B in OSCC cells were verified. Subsequently, knockdown of circMAT2B was shown to inhibit OSCC cell proliferation, migration, invasion, and the Warburg effect. Bioinformatics prediction, RNA-pull down, and luciferase reporter gene assays led to the identification of a novel TEAD1/circMAT2B/miR-942-5p/HSPD1 axis in OSCC progression. In conclusion, the novel TEAD1/circMAT2B/miR-942-5p/HSPD1 axis is a potential target for OSCC.

Comprehensive Analysis of the Significance of Ferroptosis-Related Genes in the Prognosis and Immunotherapy of Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is a life-threatening disease, associated with poor prognosis and the absence of specific biomarkers. Studies have shown that the ferroptosis-related genes (FRGs) can be used as tumor prognostic markers. However, FRGs’ prognostic value in OSCC needs further exploration. In our study, gene expression profile and clinical data of OSCC patients were collected from a public domain. We performed univariate and multivariate Cox regression analyses to construct a multigene signature. The Kaplan-Meier and receiver operating characteristic (ROC) methods were used to test the effectiveness of the signature, followed by the expression analysis of human leukocyte antigen (HLA) and immune checkpoints. The Cox regression analysis identified 4 hubs from 103 FRGs expressed in OSCC that were associated with overall survival (OS). A risk model based on the 4 FRGs was established to classify patients into high-risk and low-risk groups. Compared with the low-risk group, the survival time of the high-risk group was significantly reduced. According to the multivariate Cox regression analysis, the risk score acted as an independent predictor for OS. The accuracy of the 4 FRGs risk predictive model was confirmed by ROC curve analysis. Moreover, the low-risk group had the characteristics of higher expression of HLA and immune checkpoints, a lower tumor purity, and a higher immune infiltration, indicating a more sensitive response to immunotherapy. The novel FRGs-OSCC risk score system can be used to predict the prognosis of OSCC patients and their response to immunotherapy.

miR-532-3p suppresses proliferation and invasion of ovarian cancer cells via GPNMB/HIF-1α/HK2 axis

OBJECTIVE

Identifying a new target of miR-532-3p and studying its functional mechanism to explore the detailed anti-tumor mechanism of miR-532-3p in ovarian cancer.

METHODS

Biological and molecular methods including real-time quantitative PCR (RT-qPCR), Western blotting, colony formation, in vitro migration and invasion assays, glucose consumption and lactate production assays, RNA interference and tumor xenograft mouse models were used to study the role of miR-532-3p and its target in ovarian cancer. mRNA sequencing, dual-luciferase reporter assay and immunohistochemistry (IHC) were used to identify miR-532-3p target. STRING dataset analysis, qPCR and Western blotting were used to investigate the downstream pathway of the target of miR-532-3p.

RESULTS

Forced expression of miR-532-3p inhibited the proliferation, migration and invasion of ovarian cancer cells in vitro and the tumor growth in nude mice. RNA sequencing found 299 mRNAs were downregulated in miR-532-3p-overexpressed ovarian cancer cells, and bioinformatic analysis indicated Glycoprotein Nonmetastatic Melanoma Protein B (GPNMB), a type I membrane glycoprotein, was the potential target of miR-532-3p. GPNMB was reduced at both RNA and protein levels in miR-532-3p-overexpressed ovarian cancer cells. Dual-luciferase reporter assay determined GPNMB as the target of miR-532-3p. Interference of GPNMB inhibited the proliferation, migration, invasion, glucose consumption and lactate production of ovarian cancer cells. Knocking down of GPNMB reduced the protein level of HIF-1α without affecting HIF-1α mRNA level. Overexpression of GPNMB reversed the antitumor effect of miR-532-3p.

CONCLUSION

miR-532-3p exerted the anti-cancer effect by targeting GPNMB/ HIF-1α/ HK2 pathway to inhibit aerobic glycolysis in ovarian cancer.

Hsa_circ_0060927 Is a Novel Tumor Biomarker by Sponging miR-195-5p in the Malignant Transformation of OLK to OSCC

OBJECTIVE

To investigate the clinical significance of differentially expressed circRNAs and candidate circRNAs in the transformation of oral leukoplakia (OLK) to oral squamous cell carcinoma (OSCC).

METHODS

We performed high-throughput circRNA sequencing in six cases of normal oral mucosal (NOM) tissues, six cases of OLK tissues, and six cases of OSCC tissues. Ten circRNAs with significant differential expression were verified by qRT-PCR. Enzyme tolerance assay and Sanger sequencing were performed on the screened target circRNA hsa_circ_0060927, and a qRT-PCR assay of hsa_circ_0060927 was performed in three tissues (24 cases in each group); this was followed by an ROC analysis. The ceRNA network was predicted using TargetScan and miRanda. MiR-195-5p and TRIM14 were selected as the downstream research objects of hsa_circ_0060927. The sponge mechanism of hsa_circ_0060927 was detected by AGO2 RIP. The interaction between hsa_circ_0060927 and miR-195-5p was verified by RNA pull-down assay and dual luciferase reporter gene assay. The expressions of hsa_circ_0060927, miR-195-5p, and TRIM14 were verified by normal oral epithelial primary cells and cell lines of LEUK1, SCC9, and SCC25. The hsa_circ_0060927 overexpressed plasmid and miR-195-5p mimics were constructed to transfection LEUK1 to detect the changes in cell proliferation, apoptosis, and migration.

RESULTS

The results of qRT-PCR validation were consistent with the sequencing results. Hsa_circ_0060927 is a true circRNA with trans-splicing sites. The expression of hsa_circ_0060927 increased in NOM, OLK, and OSCC. Overexpression of hsa_circ_0060927 enhanced the ability of cell proliferation and migration, and decreased cell apoptosis capacity. The prediction of ceRNA network suggested that hsa_circ_0060927 could regulate the target gene TRIM14 through sponging miR-195-5p. AGO2 RIP indicated that hsa_circ_0060927 had a sponge mechanism. RNA pull-down and dual luciferase reporter gene assay suggested that hsa_circ_0060927 interacted with miR-195-5p. Hsa_circ_0060927 was positively correlated with the expression of TRIM14, and could relieve the inhibition of miR-195-5p on TRIM14 to regulate cell proliferation, apoptosis, and migration of LEUK1 cells.

CONCLUSION

Hsa_circ_0060927 acted as a potential key ceRNA to sponge downstream miR-195-5p and promote OLK carcinogenesis by upregulating TRIM14. Hsa_circ_0060927 was expected to be a molecular marker for the prevention and treatment of OLK carcinogenesis through the hsa_circ_0060927/miR-195-5p/TRIM14 axis.

Regulatory Mechanisms of LncRNAs in Cancer Glycolysis: Facts and Perspectives

Cancer cells exhibit distinct metabolic characteristics that employ glycolysis to provide energy and intermediary metabolites. This aberrant metabolic phenotype favors cancer progression. LncRNAs are transcripts longer than 200 nucleotides that do not encode proteins. LncRNAs contribute to cancer progression and therapeutic resistance and affect aerobic glycolysis via multiple mechanisms, including modulating glycolytic transporters and enzymes. Further, dysregulated signaling pathways are vital for glycolysis. In this review, we highlight regulatory mechanisms for lncRNAs in aerobic glycolysis that provide novel insights into cancer development. Moreover, a comprehensive understanding of the regulatory mechanisms of lncRNAs in aerobic glycolysis can provide new strategies for clinical cancer management.

Circular RNAs Regulate Glucose Metabolism in Cancer Cells

Circular RNAs (circRNAs) were originally thought to result from RNA splicing errors. However, it has been shown that circRNAs can regulate cancer onset and progression in various ways. They can regulate cancer cell proliferation, differentiation, invasion, and metastasis. Moreover, they modulate glucose metabolism in cancer cells through different mechanisms such as directly regulating glycolytic enzymes and glucose transporter (GLUT) or indirectly regulating signal transduction pathways. In this review, we elucidate on the role of circRNAs in regulating glucose metabolism in cancer cells, which partly explains the pathogenesis of malignant tumors, and provides new therapeutic targets or new diagnostic and prognostic markers for human cancers.

Circ-EGFR Functions as an Inhibitory Factor in the Malignant Progression of Glioma by Regulating the miR-183-5p/TUSC2 Axis

Circular RNAs (circRNAs) have pivotal functions in regulating diverse biological processes of human tumors, including glioma. Herein, a novel circRNA epidermal growth factor receptor (circ-EGFR, hsa_circ_0080223) was researched in glioma. The molecular expression levels were analyzed via quantitative real-time polymerase chain reaction (qRT-PCR). Cell Counting Kit-8 (CCK-8) and colony formation assays were conducted to assess cell proliferation. Apoptosis was analyzed using flow cytometry. Cell migration and invasion were examined via transwell assay. Interaction relations between targets were verified using dual-luciferase reporter assay. Tumor Suppressor Candidate 2 (TUSC2) protein expression was examined by Western blot. In vivo experiment was performed by establishing xenograft model in mice. The qRT-PCR showed the downregulation of circ-EGFR and TUSC2 but the upregulation of microRNA-183-5p (miR-183-5p) in glioma samples. In vitro assays revealed that circ-EGFR overexpression induced the repression of cell proliferation, migration, and invasion but the promotion of apoptosis. Circ-EGFR was identified as a sponge of miR-183-5p and circ-EGFR-mediated glioma progression inhibition was abolished by miR-183-5p downregulation. Additionally, miR-183-5p targeted TUSC2 and miR-183-5p inhibitor impeded the development of glioma by upregulating the expression of TUSC2. Furthermore, circ-EGFR could regulate the TUSC2 level by sponging miR-183-5p. Glioma growth in vivo was also reduced by circ-EGFR via targeting the miR-183-5p/TUSC2 axis. Altogether, our results suggested that circ-EGFR inhibited the malignant progression of glioma by regulating the levels of miR-183-5p and TUSC2. Circ-EGFR may be a useful therapeutic target to antagonize the glioma progression.

Research Progress of circRNAs in Head and Neck Cancers

Circular RNAs (circRNAs) are a novel type of non-coding RNAs. Because of their characteristics of a closed loop structure, disease- and tissue-specificity, and high conservation and stability, circRNAs have the potential to be biomarkers for disease diagnosis. Head and neck cancers are one of the most common malignant tumors with high incidence rates globally. Affected patients are often diagnosed at the advanced stage with poor prognosis, owing to the concealment of anatomic sites. The characteristics, functions, and specific mechanisms of circRNAs in head and neck cancers are increasingly being discovered, and they have important clinical significance for the early diagnosis, treatment, and prognosis evaluation of patients with cancer. In this study, the generation, characteristics, and functions of circRNAs, along with their regulatory mechanisms in head and neck cancers have been summarized. We report that circRNAs interact with molecules such as transcription and growth factors to influence specific pathways involved in tumorigenesis. We conclude that circRNAs have an important role to play in the proliferation, invasion, metastasis, energy and substance metabolism, and treatment resistance in cancers.

Down-regulating circular RNA_0004674 delays the progression of oral squamous cell carcinoma through microRNA-377-3p/THBS1 axis

OBJECTIVE

Circular RNAs (CircRNAs) are of great significance in oral squamous cell carcinoma (OSCC) cell progression. Insufficiently, the performance of Circ_0004674 has not been specified in the disease, which alighted our desire to unmask its actions in OSCC cell progression with microRNA (miR)-377-3p and thrombospondin-1 (THBS1).

METHODS

OSCC expression chip were collected through GEO database and analyzed. The upstream mechanism of THBS1 was predicted through databases. OSCC cancer tissues and normal tissues were resected, in which Circ_0004674, miR-377-3p and THBS1 expression were examined. The relationship of Circ_0004674, miR-377-3p and THBS1 was identified. Circ_0004674- and/or miR-377-3p-related oligonucleotides were transfected into CAL27 cells for detecting cell biological behaviors. Tumors in mice were implanted to monitor the tumor-forming ability of cells.

RESULTS

THBS1 showed high expression in the three OSCC chips, and it was enriched in PI3K-AKT signaling pathway. The upstream mechanism of THBS1 predicted that Circ_0004674 regulated THBS1 through miR-377-3p. Circ_0004674 and THBS1 levels were enhanced while miR-377-3p level was reduced in OSCC. Down-regulating Circ_0004674 restricted the growth of CAL27 cells in vivo and in vitro. Restoring miR-377-3p, the target gene of Circ_0004674, destroyed CAL27 cell progression and tumor growth. miR-377-3p suppression rescued the effects of down-regulated Circ_0004674 on OSCC. THBS1 was negatively mediated by miR-377-3p.

CONCLUSION

It is clarified that depleting Circ_0004674 mediates miR-377-3p to restrain THBS1, after which OSCC cell progression can be suppressed. It widens the way to control OSCC from a novel perspective.

The Circular RNA-miRNA Axis: A Special RNA Signature Regulatory Transcriptome as a Potential Biomarker for OSCC

Oral squamous cell carcinoma (OSCC) is a highly recurrent form of cancer arising from the oral epithelium, which is the result of mutational change due to etiological factors such as tobacco, smoking, chewing of areca nuts, and alcohol consumption. OSCC occurrence has been observed to be prevalent in different regions of Pacific countries and in most Asian countries. Despite the accessibility of the oral cavity, OSCC is diagnosed at an extremely late stage of pathogenic tumor node metastasis pTNM (III–IV), resulting in a poor prognosis for the individual. Therefore, it is important to make definitive, early, and efficient diagnoses. Owing to the development of omic-natured studies, the presence of proteins, transcribed elements, metabolic products, and even microflora detected in saliva helps us to select biomarkers, which is an especially exciting potential because of the availability and the non-invasive nature of sample collection. Since the discovery of circular RNA (circRNA) by Sanger sequencing, it has been reported to play a pivotal role in several human diseases, including cancer. circRNA functions as a microRNA (miRNA) sponge in the regulation of mRNA expression, forming the circRNA-miRNA regulatory axis. In the case of OSCC, overexpression of different circRNAs exhibits both tumor-progressive and tumor-suppressive effects.

Circular RNA circMDM2 accelerates the glycolysis of oral squamous cell carcinoma by targeting miR-532-3p/HK2

Circular RNAs (circRNAs) function as an essential regulator in the progression of oral squamous cell carcinoma (OSCC). However, the potential roles and mechanism of circRNAs in OSCC are still elusive. Here, this research investigates the roles and molecular mechanism of novel circRNA (circMDM2) in OSCC progression. Clinically, circMDM2 was overexpressed in OSCC tissue and cells, and the overexpression served as a poor prognostic factor for OSCC patients. Functionally, cellular experiments confirmed that circMDM2 accelerated OSCC cell proliferation and glycolysis in vitro and circMDM2 knockdown repressed the tumour growth in vivo. Mechanistically, circMDM2 sponged miR‐532‐3p to promote the hexokinase 2 (HK2), forming the circMDM2/miR‐532‐3p/HK2 axis. In conclusion, these findings demonstrated that circMDM2/miR‐532‐3p/HK2 axis promotes the proliferation and glycolysis of OSCC, rendering a potential diagnostic biomarker and prospective therapeutic target for OSCC.