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

Study on the synthesis, characterization, and antitumor mechanism investigation of QZQ-01115 via targeting sphingosine kinase 2

Sphingosine kinase 2 (SphK2) is an oncogenic enzyme that plays an essential role in the development of oral squamous cell carcinoma (OSCC). Therefore, development of SphK2 inhibitors is of great significance for the treatment of OSCC. In this study, we synthesized a series of thiazolidinediones and screened compounds with good inhibitory activity against CAL-27 using cytotoxicity assay. The compounds were further investigated in vitro using a series of in vitro experiments such as Western blot and qPCR were used to investigate the in vivo anti-tumor mechanisms, and in vivo investigation was applied by using a nude mouse ectopic tumor model. The results showed that four new compounds were successfully synthesized, and among which the compound named QZQ-01115 showed the best inhibitory activity against CAL-27 at the concentration of 5.84 ± 0.042 μM. Further mechanistic studies showed that QZQ-01115 could inhibit the proliferation, migration and invasion of CAL-27 cells at a concentration of 4 μM-6 μM. QZQ-01115 affected the PI3K/AKT signaling pathway by influencing the levels of S1P and ceramides in CAL-27, which in turn affected the mTOR/p70S6K, resulting in the blockage of protein synthesis and the blockage of cell cycle at the G0/G0 level. Apoptosis was promoted by down-regulating Bcl-2 and up-regulating Bax. The in vivo results showed that QZQ-01115 reduced the volume and weight of xenograft tumors in nude mice. The induction of apoptosis by QZQ-01115 was further determined by HE staining and immunohistochemical analysis. These results suggest that QZQ-01115 may be a potential candidate for the treatment of OSCC.

Decoding Salivary ncRNAomes as Novel Biomarkers for Oral Cancer Detection and Prognosis

Oral cancer (OC) ranks among the most prevalent head and neck cancers, becoming the eleventh most common cancer worldwide with ~350,000 new cases and 177,000 fatalities annually. The rising trend in the occurrence of OC among young individuals and women who do not have tobacco habits is escalating rapidly. Surgical procedures, radiation therapy, and chemotherapy are among the most prevalent treatment options for oral cancer. To achieve better therapy and an early detection of the cancer, it is essential to understand the disease's etiology at the molecular level. Saliva, the most prevalent body fluid obtained non-invasively, holds a collection of distinct non-coding RNA pools (ncRNAomes) that can be assessed as biomarkers for identifying oral cancer. Non-coding signatures, which are transcripts lacking a protein-coding function, have been identified as significant in the progression of various cancers, including oral cancer. This review aims to examine the role of various salivary ncRNAs (microRNA, circular RNA, and lncRNA) associated with disease progression and to explore their functions as potential biomarkers for early disease identification to ensure better survival outcomes for oral cancer patients.

Non-coding RNAs: emerging biomarkers and therapeutic targets in cancer and inflammatory diseases

Non-coding RNAs (ncRNAs) have a significant role in gene regulation, especially in cancer and inflammatory diseases. ncRNAs, such as microRNA, long non-coding RNAs, and circular RNAs, alter the transcriptional, post-transcriptional, and epigenetic gene expression levels. These molecules act as biomarkers and possible therapeutic targets because aberrant ncRNA expression has been directly connected to tumor progression, metastasis, and response to therapy in cancer research. ncRNAs' interactions with multiple cellular pathways, including MAPK, Wnt, and PI3K/AKT/mTOR, impact cellular processes like proliferation, apoptosis, and immune responses. The potential of RNA-based therapeutics, such as anti-microRNA and microRNA mimics, to restore normal gene expression is being actively studied. Additionally, the tissue-specific expression patterns of ncRNAs offer unique opportunities for targeted therapy. Specificity, stability, and immune responses are obstacles to the therapeutic use of ncRNAs; however, novel strategies, such as modified oligonucleotides and targeted delivery systems, are being developed. ncRNA profiling may result in more individualized and successful treatments as precision medicine advances, improving patient outcomes and creating early diagnosis and monitoring opportunities. The current review aims to investigate the roles of ncRNAs as potential biomarkers and therapeutic targets in cancer and inflammatory diseases, focusing on their mechanisms in gene regulation and their implications for non-invasive diagnostics and targeted therapies. A comprehensive literature review was conducted using PubMed and Google Scholar, focusing on research published between 2014 and 2025. Studies were selected based on rigorous inclusion criteria, including peer-reviewed status and relevance to ncRNA roles in cancer and inflammatory diseases. Non-English, non-peer-reviewed, and inconclusive studies were excluded. This approach ensures that the findings presented are based on high-quality and relevant sources.

Upregulation of circGDI2 inhibits tumorigenesis by stabilizing the expression of RNA m6A demethylase FTO in oral squamous cell carcinoma

Background

Oral squamous cell carcinoma (OSCC) is a malignant tumour that is difficult to identify and prone to metastasis and invasion. Circular RNAs (circRNAs) are important cancer regulators and can be used as potential biomarkers. However, OSCC-related circRNAs need to be further explored. We investigated the role of circGDI2 in OSCC and explored its downstream regulatory mechanisms.

Methods

Quantitative real-time PCR was used to detect the expression levels of circGDI2 and fat mass and obesity-associated protein (FTO) in cells. Lentiviral transfection was used to construct stable circGDI2 overexpressing cells for subsequent cell function tests. RNA pull-down, RNA Immunoprecipitation (RIP), western blotting, and protein stability assays were conducted to detect circGDI2 binding proteins and their functions. CCK8, Transwell, and wound healing assays were used to verify cell functions after overexpressing circGDI2 or suppressing FTO expression. Animal experiments were performed to verify the results in vivo.

Results

The expression of circGDI2 was markedly decreased in both OSCC cell lines and patient tissues. Overexpression of circGDI2 in OSCC cell lines led to decreased proliferation, migration, and invasion abilities. Knockdown of circGDI2 showed the opposite trend. CircGDI2 has been validated to interact with the FTO protein within cells, as evidenced by mass spectrometry and RIP assays. This interaction was found to prevent the degradation of the FTO protein. Dot blot analysis showed a reduction in N6-methyladenosine (m6A) modification after circGDI2 overexpression. Reduced FTO levels reversed the inhibitory effects of circGDI2 overexpression on cell proliferation, migration, and invasion in vitro and on tumorigenesis in vivo.

Conclusions

CircGDI2 functions as a tumour suppressor by binding to the FTO protein to reduce RNA m6A modification levels and ultimately inhibit proliferation and migration in OSCC cells. This study indicates the potential use of circGDI2 as a new target for the prevention and treatment of OSCC.

The oncogenic potential of salivary microRNA-93 and microRNA-412-3p in oral lichen planus: a case-control study

BACKGROUND

Oral Lichen Planus is one of the most popular chronic mucocutaneous diseases. It is classified as potentially malignant lesions. Many microRNAs can be used as biological markers for the disease and for its malignant transformation. The aim of the study to measure the expression of microRNA-93 and microRNA-412-3p in Oral Lichen Planus patients, patients diagnosed as Oral Squamous Cell Carcinoma and healthy controls.

METHODOLOGY

A total of 60 patients were divided into 3 groups; each group contains 20 patients. Group I for Oral Lichen Planus patients, group II for healthy controls and group III for Oral Squamous cell carcinoma patients. All of these patients were chosen from those attending Kasr Al-Einy hospital, Cairo University. After full diagnosis and matching of our eligibility criteria, saliva sample was taken from each patient to measure the concentration of microRNA-93 and microRNA-412-3p.

RESULTS

Both microRNA-93 and miceoRNA-412-3p were upregulated in Oral Squamous cell carcinoma patients than Oral Lichen patients than controls and both of them had great sensitivity, specificity and diagnostic accuracy for both Oral Lichen Planus and Oral Squamous cell carcinoma.

CONCLUSION

MicroRNA-93 and micriRNA-412-3p can be used as diagnostic markers and for the oncogenic potential of Oral Lichen Planus.

circAGO3 facilitates NF-κB pathway-mediated inflammatory atrophy in chicken skeletal muscle via the miR-34b-5p/TRAF3 axis

Circular RNAs have emerged as critical regulators of gene expression across various biological systems. In this study, circAGO3, originating from exons 5, 6, 7, and 8 of the AGO3 gene in chickens, is characterized for its stability and differential expression during both embryonic and post-hatch stages. Overexpression of circAGO3 in chicken skeletal muscle markedly disrupts myogenesis by downregulating muscle differentiation markers and upregulating genes associated with muscle atrophy. RNA sequencing and functional analyses further delineate circAGO3's involvement in modulating inflammatory responses through the NF-κB signaling pathway, mediated by its interaction with miR-34b-5p. These findings highlight circAGO3's potential importance in poultry production by uncovering its regulatory roles in skeletal muscle development and inflammation, positioning it as a promising target for enhancing muscle growth and health in poultry farming.

Circ_0002722-induced regulation of YAP promotes platinum resistance in oral squamous cell carcinoma: Implications for verteporfin therapy

Oral squamous cell carcinoma (OSCC) poses a significant public health burden due to its high prevalence and poor prognosis. Platinum resistance is one of the major challenges in OSCC treatment. Yes-associated protein (YAP) has been identified as a pivotal player in OSCC tumorigenesis and progression. Circular RNA (circRNA) has been implicated in chemoresistance in various cancers by regulation the function of microRNA. Nevertheless, the specific mechanisms linking circRNA to YAP expression in OSCC remain poorly understood. In this study, we detected the YAP and circRNA hsa_circ_0002722 (circ_0002722) expression by western blot (WB) and quantitative polymerase chain reaction (qPCR). We found that YAP and circ_0002722 were up-regulated in platinum resistance in OSCC tissues. Furthermore, transfection of circ_0002722 siRNA into platinum-resistant cells revealed that circ_0002722 acted as a regulator of miR-1305, which influenced YAP expression and thereby affected platinum sensitivity. In vivo experiments corroborated the synergistic effects of cisplatin and verteporfin (a YAP inhibitor) in combating platinum resistance. Targeting YAP emerges as a promising therapeutic strategy for addressing platinum resistance in OSCC, with circ_0002722 serving as a potential therapy target and valuable diagnostic marker. These findings shed light on the underlying mechanisms of platinum resistance, paving the way for the development of effective treatment approaches.

Identification of Stage-Specific microRNAs that Govern the Early Stages of Sequential Oral Oncogenesis by Strategically Bridging Human Genetics with Epigenetics and Utilizing an Animal Model

Oral squamous cell carcinoma (OSCC) is a highly prevalent and aggressive malignancy, with mortality rates reaching 60%, mainly due to its excessive diagnostic delay. MiRNAs, a class of crucial epigenetic gene-expression regulators, have emerged as potential diagnostic biomarkers, with >200 molecules exhibiting expressional dysregulation in OSCC. We had previously established an in silico methodology for the identification of the most disease-specific molecules by bridging genetics and epigenetics. Here, we identified the stage-specific miRNAs that govern the asymptomatic early stages of oral tumorigenesis by exploiting seed-matching and the reverse interplay between miRNA levels and their target genes' expression. Incorporating gene-expression data from our group's experimental hamster model of sequential oral oncogenesis, we bioinformatically detected the miRNAs that simultaneously target/regulate >75% of the genes that are characteristically upregulated or downregulated in the consecutive stages of hyperplasia, dysplasia, and early invasion, while exhibiting the opposite expressional dysregulation in OSCC-derived tissue and/or saliva specimens. We found that all stages share the downregulation of miR-34a-5p, miR124-3p, and miR-125b-5p, while miR-1-3p is under-expressed in dysplasia and early invasion. The malignant early-invasion stage is distinguished by the downregulation of miR-147a and the overexpression of miR-155-5p, miR-423-3p, and miR-34a-5p. The identification of stage-specific miRNAs may facilitate their utilization as biomarkers for presymptomatic OSCC diagnosis.

Cisplatin-based miRNA delivery strategy inspired by the circCPNE1/miR-330-3p pathway for oral squamous cell carcinoma

Circular RNAs (circRNAs) are ideal biomarkers of oral squamous cell carcinoma (OSCC) because of their highly stable closed-loop structure, and they can act as microRNA (miRNA) sponges to regulate OSCC progression. By analyzing clinical samples, we identified circCPNE1, a dysregulated circRNA in OSCC, and its expression level was negatively correlated with the clinical stage of OSCC patients. Gain-of-function assays revealed the tumor-suppressive effect of circCPNE1, which was then identified as a miR-330-3p sponge. MiR-330-3p was recognized as a tumor promoter in multiple studies, consistent with our finding that it could promote the proliferation, migration, and invasion of OSCC cells. These results indicated that selective inhibition of miR-330-3p could be an effective strategy to inhibit OSCC progression. Therefore, we designed cationic polylysine-cisplatin prodrugs to deliver antagomiR-330-3p (a miRNA inhibitory analog) via electrostatic interactions to form PP@miR nanoparticles (NPs). Paratumoral administration results revealed that PP@miR NPs effectively inhibited subcutaneous tumor progression and achieved partial tumor elimination (2/5), which confirmed the critical role of miR-330-3p in OSCC development. These findings provide a new perspective for the development of OSCC treatments.

Circular RNAs: a small piece in the heart failure puzzle

Cardiovascular disease, specifically heart failure (HF), remains a significant concern in the realm of healthcare, necessitating the development of new treatments and biomarkers. The RNA family consists of various subgroups, including microRNAs, PIWI-interacting RNAs (piRAN) and long non-coding RNAs, which have shown potential in advancing personalized healthcare for HF patients. Recent research suggests that circular RNAs, a lesser-known subgroup of RNAs, may offer a novel set of targets and biomarkers for HF. This review will discuss the biogenesis of circular RNAs, their unique characteristics relevant to HF, their role in heart function, and their potential use as biomarkers in the bloodstream. Furthermore, future research directions in this field will be outlined. The stability of exosomal circRNAs makes them suitable as biomarkers, pathogenic regulators, and potential treatments for cardiovascular diseases such as atherosclerosis, acute coronary syndrome, ischemia/reperfusion injury, HF, and peripheral artery disease. Herein, we summarized the role of circular RNAs and their exosomal forms in HF diseases.

Exosomal circRNAs: Novel biomarkers and therapeutic targets for urinary tumors

Exosomal circRNAs have emerged as promising biomarkers and therapeutic targets for urinary tumors. In this review, we explored the intricate role of exosomal circRNAs in urological cancers, focusing on their biological functions, dysregulation in tumors, and potential clinical applications. The review delves into the mechanisms by which exosomal circRNAs contribute to tumor progression and highlights their diagnostic and therapeutic implications. By synthesizing current research findings, we present a compelling case for the significance of exosomal circRNAs in the context of urinary tumors. Furthermore, the review discusses the challenges and opportunities associated with utilizing exosomal circRNAs as diagnostic tools and targeted therapeutic agents. There is a need for further research to elucidate the specific mechanisms of exosomal circRNA secretion and delivery, as well as to enhance the detection methods for clinical translational applications. Overall, this comprehensive review underscores the pivotal role of exosomal circRNAs in urinary tumors and underscores their potential as valuable biomarkers and therapeutic tools in the management of urological cancers.

Circular RNA-Mediated Regulation of Oral Tissue-Derived Stem Cell Differentiation: Implications for Oral Medicine and Orthodontic Applications

Circular RNAs (circRNAs) are a novel class of endogenous non-coding RNAs (ncRNAs) which unlike linear RNAs, have a covalently closed continuous loop structure. circRNAs are found abundantly in human cells and their biology is complex. They feature unique expression to different types of cells, tissues, and developmental stages. To the present, the functional roles of circular RNAs are not fully understood. They reportedly act as microRNA (miRNA) sponges, therefore having key regulatory functions in diverse physiological and pathological processes. As for dentistry field, lines of evidence indicate that circRNAs play vital roles in the odontogenic and osteogenic differentiation of dental pulp stem cells (DPSCs) and periodontal ligament stem cells (PDLSCs). Abnormal expression of circRNAs have been found in other areas of pathology frequently reflected also in the oral environment, such as inflammation or bone and soft tissue loss. Therefore, circRNAs could be of significant importance in various fields in dentistry, especially in bone and soft tissue engineering and regeneration. Understanding the molecular mechanisms occurring during the regulation of oral biological and tissue remodeling processes could augment the discovery of novel diagnostic biomarkers and therapeutic strategies that will improve orthodontic and other oral therapeutic protocols.

Circ_ST6GAL1-mediated competing endogenous RNA network regulates TGF-β1-stimulated matrix Metalloproteinase-13 expression via Runx2 acetylation in osteoblasts

Transforming growth factor-beta1 (TGF-β1) stimulates matrix metalloproteinase-13 (MMP-13, a bone-remodeling gene) expression, and this effect requires p300-mediated Runx2 (Runt-related transcription factor 2) acetylation in osteoblasts. p300 and Runx2 are transcriptional coactivator and bone transcription factor, respectively, which play key roles in the regulation of bone-remodeling genes. Non-coding ribonucleic acids (ncRNAs), such as long ncRNAs (lncRNAs) and microRNAs (miRNAs), have been linked to both physiological and pathological bone states. In this study, we proposed that TGF-β1-mediated stimulation of MMP-13 expression is due to the downregulation of p300 targeting miRNAs in osteoblasts. We identified miR-130b-5p as one of the miRNAs downregulated by TGF-β1 in osteoblasts. Forced expression of miR-130b-5p decreased p300 expression, Runx2 acetylation, and MMP-13 expression in these cells. Furthermore, TGF-β1 upregulated circ_ST6GAL1, (a circular lncRNA) in osteoblasts; circRNA directly targeted miR-130b-5p. Antisense-mediated knockdown of circ_ST6GAL1 restored the function of miR-130b-5p, resulting in downregulation of p300, Runx2, and MMP-13 in these cells. Hence, our results suggest that TGF-β1 influences circ_ST6GAL1 to sponge and degrade miR-130b-5p, thereby promoting p300-mediated Runx2 acetylation for MMP-13 expression in osteoblasts. Thus, the circ_ST6GAL1/miR-130b-5p/p300 axis has potential significance in the treatment of bone and bone-related disorders.

Biolinguistic graph fusion model for circRNA-miRNA association prediction

Emerging clinical evidence suggests that sophisticated associations with circular ribonucleic acids (RNAs) (circRNAs) and microRNAs (miRNAs) are a critical regulatory factor of various pathological processes and play a critical role in most intricate human diseases. Nonetheless, the above correlations via wet experiments are error-prone and labor-intensive, and the underlying novel circRNA-miRNA association (CMA) has been validated by numerous existing computational methods that rely only on single correlation data. Considering the inadequacy of existing machine learning models, we propose a new model named BGF-CMAP, which combines the gradient boosting decision tree with natural language processing and graph embedding methods to infer associations between circRNAs and miRNAs. Specifically, BGF-CMAP extracts sequence attribute features and interaction behavior features by Word2vec and two homogeneous graph embedding algorithms, large-scale information network embedding and graph factorization, respectively. Multitudinous comprehensive experimental analysis revealed that BGF-CMAP successfully predicted the complex relationship between circRNAs and miRNAs with an accuracy of 82.90% and an area under receiver operating characteristic of 0.9075. Furthermore, 23 of the top 30 miRNA-associated circRNAs of the studies on data were confirmed in relevant experiences, showing that the BGF-CMAP model is superior to others. BGF-CMAP can serve as a helpful model to provide a scientific theoretical basis for the study of CMA prediction.

Circ-ILF2 in oral squamous cell carcinoma promotes cisplatin resistance and induces M2 polarization of macrophages

Cisplatin (CDDP) chemoresistance is one of the predominant factors in oral squamous cell carcinoma (OSCC) treatment failure. Uncovering the mechanisms underlying CDDP resistance is of great importance in OSCC therapy. Circular RNAs (circRNAs) are a newly discovered class of noncoding RNAs, which are reported to participate in the progression of various diseases, including cancer. However, the function of circRNAs in CDDP resistance in OSCC remains unclear. Quantitative reverse transcription PCR was used to search for different circRNAs between OSCC cell lines and CDDP-resistant cell lines. The results showed that circ-ILF2 expression was higher in CDDP-resistant OSCC cell lines. The stability of circ-ILF2 was also confirmed using RNase R and actinomycin D assays. Functional experiments, including cytotoxicity, apoptosis and growth rate assays, showed that upregulation of circ-ILF2 contributes to CDDP resistance. Luciferase reporter-gene, RNA pull-down and quantitative real-time PCR (RT-qPCR) assays showed that circ-ILF2 functions as a microRNA sponge for miR-1252. Luciferase reporter assays, RNA pull-down, RT-qPCR and Western blotting showed that miR-1252 directly targeted and regulated the expression of KLF8. Circ-ILF2 plays an important role in CDDP resistance in OSCC. Circ-ILF2 exerts its function through the miR-1252/KLF8 pathway. In addition, tumour-associated macrophages (TAM) play important roles in cancer progressions, our results showed that circ-ILF2 in OSCC cells induced the M2 polarization of macrophages which provided new thoughts on immunotherapy. Our results suggest that circ-ILF2 may represent a potential therapeutic target in CDDP-resistant OSCC.

Research Progress of Metformin in the Treatment of Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is one of the most common malignancies and has a high mortality, posing a great threat to both human physical and mental health. With the advancement of scientific research, a variety of cancer therapies have been used for OSCC treatment. However, the prognosis of OSCC shows no significant improvement. Metformin has been recognized as the first-line drug for the treatment of diabetes, and recent studies have shown that metformin has a remarkable suppressive effect on tumor progression. Metformin can not only affect the energy metabolism of tumor cells but also play an antitumor role by modulating the tumor microenvironment and cancer stem cells. In this review, the molecular mechanism of metformin and its anticancer mechanism in OSCC are summarized. In addition, this article summarizes the side effects of metformin and the future prospects of its application in the treatment of OSCC.

Extracellular vesicles in gastric cancer: role of exosomal lncRNA and microRNA as diagnostic and therapeutic targets

Extracellular vesicles (EVs), including exosomes, play a crucial role in intercellular communication and have emerged as important mediators in the development and progression of gastric cancer. This review discusses the current understanding of the role of EVs, particularly exosomal lncRNA and microRNA, in gastric cancer and their potential as diagnostic and therapeutic targets. Exosomes are small membrane-bound particles secreted by both cancer cells and stromal cells within the tumor microenvironment. They contain various ncRNA and biomolecules, which can be transferred to recipient cells to promote tumor growth and metastasis. In this review, we highlighted the importance of exosomal lncRNA and microRNA in gastric cancer. Exosomal lncRNAs have been shown to regulate gene expression by interacting with transcription factors or chromatin-modifying enzymes, which regulate gene expression by binding to target mRNAs. We also discuss the potential use of exosomal lncRNAs and microRNAs as diagnostic biomarkers for gastric cancer. Exosomes can be isolated from various bodily fluids, including blood, urine, and saliva. They contain specific molecules that reflect the molecular characteristics of the tumor, making them promising candidates for non-invasive diagnostic tests. Finally, the potential of targeting exosomal lncRNAs and microRNAs as a therapeutic strategy for gastric cancer were reviewed as wee. Inhibition of specific molecules within exosomes has been shown to suppress tumor growth and metastasis in preclinical models. In conclusion, this review article provides an overview of the current understanding of the role of exosomal lncRNA and microRNA in gastric cancer. We suggest that further research into these molecules could lead to new diagnostic tools and therapeutic strategies for this deadly disease.

Computational insights of excited state intramolecular proton transfer (ESIPT) based fluorescent detection and imaging of γ-glutamytranspeptidase activity

γ-Glutamytranspeptidase (GGT) is an important tumor biomarker that widely appears in the tumor cells. Therefore, accurate imaging and detection of GGT activity in live cells, serum and pathological cells grasp great importance for the diagnosis, management, and treatment of cancer. Herein, 2-(2-hydroxyl-phenyl)-6-chloro-4-(3H)-quinazolinone (HPQ) is considered as the fluorophore probe for the detection of GGT activity, which is known for the typical mechanism of excited-state intramolecular proton transfer (ESIPT). All the simulations adopted to evaluate the sensing mechanism were carried out via DFT and TDDFT calculations at CAM-B3LYP/TZVP level of theory. The emission properties of HPQ and HPQ-TD are thoroughly studied to understand the photoinduced electron transfer (PET) and excited state intramolecular proton transfer (ESIPT) process. The results reveal that the fluorescence quenching of HPQ (enol form) is assigned to the PET process, whereas the large Stokes shift in fluorescence emission of HPQ (keto form) is related with ESIPT mechanism. The obtained results are further cross validated by frontier molecular orbital (FMO) analysis, geometric analysis, and potential energy curve (PEC) scanning. Our calculations provide powerful evidence for the ESIPT based sensing mechanism of HPQ (keto-enol form) for GGT activity.

circFANCA accelerates the malignant process of OSCC by modulating miR-34a/PA28γ signaling

OBJECTIVES

To investigate the upstream regulatory molecules of proteasomal activator 28γ (PA28γ), and explore its specific regulatory mechanism and potential clinical significance in OSCC.

MATERIALS AND METHODS

qPCR was used to examine miR-34a, circFANCA and PSME3 expression. Western blotting was adopted to detect PA28γ expression. Transwell experiments were conducted to evaluate OSCC cell migration and invasion ability. FISH was used to evaluate the subcellular localization of circFANCA and miR-34a, and RNA pull-down verified the interaction between them. The expression of circFANCA and miR-34a in clinical cohorts was assessed by ISH, and the results were subjected to survival analysis using Kaplan-Meier analysis.

RESULTS

Here, we proved that miR-34a expression is lower in highly aggressive OSCC tissues and cell lines. Notably, miR-34a can downregulate PA28γ expression and inhibit OSCC invasion and migration. Next, we confirmed that circFANCA promoted OSCC cell metastatic ability by sponging miR-34a. Importantly, interfering with miR-34a rescued the malignant progression of OSCC induced by silencing circFANCA. Finally, clinical data showed lower miR-34a expression and higher circFANCA expression were associated with poor prognosis in OSCC patients.

CONCLUSION

The circFANCA/miR-34a/PA28γ axis facilitates the metastasis of OSCC, and circFANCA and miR-34a have potential to serve as prognostic markers for OSCC patients.

Association of genetic variants of CircCHST15 with oral squamous cell carcinoma in the Chinese Han population

BACKGROUND

Oral squamous cell carcinoma (OSCC) is the most common cancer in the oral cavity. The relationship between the genetic susceptibility of circCHST15 and OSCC remains unclear.

METHODS

Genetic variants of circCHST15 were screened using a genotyping analysis from 1044 patients with OSCC and 3199 healthy participants. The circCHST15 expression was detected in 32 pairs of OSCC tissues. The circular RNA quantitative trait locus analysis and the reporter gene assay were performed for verification.

RESULTS

The circCHST15 expression was upregulated in OSCC (Wilcoxon p < 1e-3). The genotyping analysis screened out 61 loci in circCHST15 associated with the risk of OSCC. After adjustment and annotation, rs28707473 (A > C, odds ratio = 1.21, 95% CI: 1.076-1.361, p = 1.453e-3) was selected. This genetic variation could elevate the circCHST15 expression level possibly by altering the structure of circular RNAs and affecting transcription factor binding.

CONCLUSIONS

The results of this study suggested that genetic variants of circCHST15 may contribute to OSCC susceptibility.

Relevance of micro-RNAs and their targets as a diagnostic and prognostic marker in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) ranks sixth among all cancers in the world, affecting various sites of the oral cavity with associated several risk factors. High mortality has been associated with the presence of metastasis during the time of diagnosis and an increase in therapeutic relapses. Micro-RNAs (miRNAs) are a group of small non-coding RNAs with salient roles in the initiation and progression of cancer. The tumorigenesis of OSCC is associated with the dysregulation of several miRNAs. MicroRNAs are an area of recent interest, and numerous studies have been reported and are being undertaken to identify their role in diagnostic and prognostic value for oral cancers. Most of the miRNA processing machinery is considered to be either up-/down-regulated in OSCC, but the underlying mechanism of miRNA dysregulation and their activity as either a tumour suppressor or an oncogene in oral carcinogenesis is not yet clear. The article presents a concise review of the available current literature regarding the various miRNAs' signatures in OSCC and their role as diagnostic/prognostic biomarkers.

Exosomal circular RNAs: A chief culprit in cancer chemotherapy resistance

Chemotherapy is one of the primary treatments for malignant tumors. However, the acquired drug resistance hinders clinical efficacy and leads to treatment failure in most patients. Exosomes are cell-derived vesicles with a diameter of 30-150 nm carrying and delivering substances such as DNAs, RNAs, lipids, and proteins for cellular communication in tumor development. Circular RNAs (circRNAs) present covalently closed-loop RNA structures, which regulate tumor cell proliferation, apoptosis, and metastasis by controlling different genes and signaling pathways. CircRNAs are abundant and stably expressed in exosomes. Recent studies have shown that they play critical roles in chemotherapy resistance in various cancers. In this review, we summarized the origin of exosomes and discussed the regulation mechanism of exosomal circRNAs in cancer drug resistance.

Regulation of mRNA stability contributes to the function of innate lymphoid cells in various diseases

Innate lymphoid cells (ILCs) are important subsets of innate immune cells that regulate mucosal immunity. ILCs include natural killer cells, innate lymphoid cells-1 (ILC1s), ILC2s, and ILC3s, which have extremely important roles in the immune system. In this review, we summarize the regulation of mRNA stability mediated through various factors in ILCs (e.g., cytokines, RNA-binding proteins, non-coding RNAs) and their roles in mediating functions in different ILC subsets. In addition, we discuss potential therapeutic targets for diseases such as chronic obstructive pulmonary disease, cancer, and pulmonary fibrosis by regulation of mRNA stability in ILCs, which may provide novel directions for future clinical research.

Circular RNA in Retina: A Potential Biomarker and Therapeutic Target

Circular RNA (circRNA) is a newly discovered noncoding RNA, which forms a closed ring with more than 200 bases in length. CircRNA is formed by back splicing of precursor RNA, and its expression abundance in body fluid is up to 10 times that of homologous linear transcripts. Recently, novel activities for circRNA in various diseases have emerged, ranging from cancer therapy and neurodegenerative diseases. Here, we reviewed the literature on the biogenesis of circRNA and its relationship with retinal diseases in recent years. We first described the mechanism, existing form and main function of circRNA. Next, we also pinpoint that circRNA has great value in the diagnosis and treatment of retinal diseases represented by retinoblastoma, retinal degeneration, and diabetic retinopathy. By this review, we hope to explore more possibilities of circRNA in clinical diagnosis and treatment.

Circ_CUX1/miR-130b-5p/p300 axis for parathyroid hormone-stimulation of Runx2 activity in rat osteoblasts: A combined bioinformatic and experimental approach

Parathyroid hormone (PTH) regulates the expression of bone remodeling genes by enhancing the activity of Runx2 in osteoblasts. p300, a histone acetyltransferase, acetylated Runx2 to activate the expression of its target genes. PTH stimulated the expression of p300 in rat osteoblastic cells. Increasing studies suggested the potential of non-coding RNAs (ncRNAs), such as microRNAs (miRNAs) and circular RNAs (circRNAs), in regulating gene expression under both physiological and pathological conditions. In this study, we hypothesized that PTH regulates Runx2 activity via ncRNAs-mediated p300 expression in rat osteoblastic cells. Bioinformatics and experimental approaches identified PTH-upregulation of miR-130b-5p and circ_CUX1 that putatively target p300 and miR-130b-5p, respectively. An antisense-mediated knockdown of circ_CUX1 was performed to determine the sponging activity of circ_CUX1. Knockdown of circ_CUX1 promoted miR-130b-5p activity and reduced p300 expression, resulting in decreased Runx2 acetylation in rat osteoblastic cells. Further, bioinformatics analysis identified the possible signaling pathways that regulate Runx2 activity and osteoblast differentiation via circ_CUX1/miR-130b-5p/p300 axis. The predicted circ_CUX1/miR-130b-5p/p300 axis might pave the way for better diagnostic and therapeutic approaches for bone-related diseases.

Construction and validation of a metabolic-related genes prognostic model for oral squamous cell carcinoma based on bioinformatics

BACKGROUND

Oral squamous cell carcinoma (OSCC) accounts for a frequently-occurring head and neck cancer, which is characterized by high rates of morbidity and mortality. Metabolism-related genes (MRGs) show close association with OSCC development, metastasis and progression, so we constructed an MRGs-based OSCC prognosis model for evaluating OSCC prognostic outcome.

METHODS

This work obtained gene expression profile as well as the relevant clinical information from the The Cancer Genome Atlas (TCGA) database, determined the MRGs related to OSCC by difference analysis, screened the prognosis-related MRGs by performing univariate Cox analysis, and used such identified MRGs for constructing the OSCC prognosis prediction model through Lasso-Cox regression. Besides, we validated the model with the GSE41613 dataset based on Gene Expression Omnibus (GEO) database.

RESULTS

The present work screened 317 differentially expressed MRGs from the database, identified 12 OSCC prognostic MRGs through univariate Cox regression, and then established a clinical prognostic model composed of 11 MRGs by Lasso-Cox analysis. Based on the optimal risk score threshold, cases were classified as low- or high-risk group. As suggested by Kaplan-Meier (KM) analysis, survival rate was obviously different between the two groups in the TCGA training set (P < 0.001). According to subsequent univariate and multivariate Cox regression, risk score served as the factor to predict prognosis relative to additional clinical features (P < 0.001). Besides, area under ROC curve (AUC) values for patient survival at 1, 3 and 5 years were determined as 0.63, 0.70, and 0.76, separately, indicating that the prognostic model has good predictive accuracy. Then, we validated this clinical prognostic model using GSE41613. To enhance our model prediction accuracy, age, gender, risk score together with TNM stage were incorporated in a nomogram. As indicated by results of ROC curve and calibration curve analyses, the as-constructed nomogram had enhanced prediction accuracy compared with clinicopathological features alone, besides, combining clinicopathological characteristics with risk score contributed to predicting patient prognosis and guiding clinical decision-making.

CONCLUSION

In this study, 11 MRGs prognostic models based on TCGA database showed superior predictive performance and had a certain clinical application prospect in guiding individualized.

circ-Ncam2 (mmu_circ_0006413) Participates in LPS-Induced Microglia Activation and Neuronal Apoptosis via the TLR4/NF-κB Pathway

Spinal cord injury (SCI) can cause permanent neurological deficits. Circular RNA Ncam2 (circ-Ncam2 also termed mmu_circ_0006413) has been reported to be overexpressed in SCI mouse models. However, the function of circ-Ncam2 in SCI has not been validated. Lipopolysaccharide (LPS) was used to activate mouse microglia (BV2 cells). Expression levels of circ-Ncam2 were determined by RT-qPCR. Relative protein levels were evaluated by western blotting. Cytokines were determined by ELISA. The regulatory mechanism of circ-Ncam2 was validated by dual-luciferase reporter and RNA pull-down assays. Effects of LPS-induced BV2 cells on mouse neuronal (HT22 cells) viability, proliferation, and apoptosis were analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium Bromide (MTT), 5-ethynyl-2'-deoxyuridine (EdU), and flow cytometry assays. LPS stimulation promoted circ-Ncam2 expression in BV2 cells. Inhibition of circ-Ncam2 mitigated LPS-induced BV2 cell activation and inflammation. Mechanically, circ-Ncam2 adsorbed miR-544-3p to regulate TLR4 expression. Also, either miR-544-3p inhibition or TLR4 overexpression weakened circ-Ncam2 silencing-mediated effects on LPS-induced BV2 cell activation and inflammation. Furthermore, LPS-induced BV2 cells suppressed HT22 cell proliferation and promoted HT22 cell apoptosis through the circ-Ncam2/miR-544-3p axis. Importantly, circ-Ncam2 activated the NF-κB signaling via the miR-544-3p/TLR4axis. circ-Ncam2 silencing lowered LPS-induced microglia activation and neuronal apoptosis via blocking the TLR4/NF-κB pathway through acting as a miR-544-3p sponge, suggesting that circ-Ncam2 may be involved in secondary SCI.

Circular GOLPH3 RNA exerts oncogenic effects in vitro by regulating the miRNA-1299/LIF axis in oral squamous cell carcinoma

Circular RNAs, which are a novel subclass of noncoding RNAs, are reported to be involved in various biological processes. Aberrant expression of circular RNAs may promote cancer progression. The function of circular GOLPH3 RNA (circGOLPH3) in oral squamous cell carcinoma (OSCC) is unclear. In this study, the circGOLPH3 levels in OSCC cell lines were determined using quantitative real-time polymerase chain reaction (qRT-PCR). Gain-of-function and loss-of-function experiments were performed to evaluate the roles of circGOLPH3 in OSCC. Cell counting kit 8, migration, and invasion assays were performed to determine the functions of circGOLPH3. The mechanism of circGOLPH3 in OSCC was investigated using qRT-PCR, western blotting, luciferase activity, and RNA pull-down analyses. Furthermore, the function of circGOLPH3 in vivo was evaluated. circGOLPH3 derived from GOLPH3 was mainly localized to the cytoplasm and exhibited high stability. The expression of circGOLPH3 was upregulated in OSCC cells. circGOLPH3 promoted the growth of OSCC in vitro and in vivo. Additionally, circGOLPH3 upregulated OSCC cell migration and invasion. Mechanistically, circGOLPH3 functioned as a microRNA sponge and downregulated miR-1299 expression. miR-1299 downregulated the expression of LIF by targeting its 3’-untranslated region. Inhibition of the circGOLPH3/miR-1299/LIF axis suppressed the growth, migration, and invasion of OSCC cells. These findings indicate that the circGOLPH3/miR-1299/LIF axis promotes OSCC cell growth, migration, and invasion and that this axis is a potential therapeutic target for OSCC.

Downregulation of circLPAR3 inhibits tumor progression and glycolysis by liberating miR‐144‐3p and upregulating LPCAT1 in oral squamous cell carcinoma

Background

Increasing evidence demonstrated the important roles of circular RNAs (circRNAs) in human cancer progression, including oral squamous cell carcinoma (OSCC). The study intentions were to explore the role and molecular mechanism of hsa_circ_0004390 (circLPAR3) in OSCC progression.

Methods

Expression of circLPAR3 in collected samples and cultured cell lines was detected with real‐time quantitative reverse transcription‐polymerase chain reaction (RT‐qPCR). Loss‐of‐function experiments were performed to determine the effect of circLPAR3 silencing on OSCC cell proliferation, migration, invasion, apoptosis, angiopoiesis, and glycolysis. The sponge function of circLPAR3 was predicted by bioinformatics analysis and validated by the dual‐luciferase reporter and RNA pull‐down assays. In vivo experiments were conducted to validate the function of circLPAR3.

Results

A marked increase in circLPAR3 expression was observed in OSCC samples and cell lines. Furthermore, circLPAR3 could distinguish OSCC samples from paired non‐tumor samples, and patients with high circLPAR3 expression had a poor prognosis. Furthermore, circLPAR3 inhibition decreased OSCC growth in xenograft mouse models. Moreover, circLPAR3 silencing repressed cell proliferation, migration, invasion, angiopoiesis, glycolysis, and induced cell apoptosis in OSCC cells in vitro. Mechanically, circLPAR3 sponged miR‐144‐3p to prohibit the inhibiting effect of miR‐144‐3p on LPCAT1, thus promoting OSCC progression.

Conclusion

CircLPAR3 exerted a tumor‐promoting effect on OSCC growth through elevating LPCAT1 expression via functioning as a miR‐144‐3p sponge. This study supports the possible role of circLPAR3 in the diagnosis, prognosis, and treatment of OSCC.

hnRNP L-activated circANKRD42 Reverse Splicing and the circANKRD42-mediated Crosstalk between Mechanical Stiffness and Biochemical Signals to Drive Pulmonary Fibrogenesis

Increasing circular RNAs (circRNAs) are involved in the progression of idiopathic pulmonary fibrosis (IPF). However, circRNA biogenesis and circRNA-mediated crosstalk between mechanical stiffness and biochemical signals in IPF remain obscure. In this study, a novel circRNA-ANKRD42 from peripheral blood of patients with IPF, which participated in pulmonary fibrosis through the close communication of mechanical stiffness and biochemical signals, was identified. Mechanistic studies revealed that the heterogeneous nuclear ribonucleoprotein L (hnRNP L) activated the circANKRD42 reverse splicing biogenesis. The biogenetic circANKRD42 sponged miR-324-5p to promote the AJUBA expression, which blocked the binding between phosphorylated yes-associated protein 1 (YAP1) and large tumor suppressor kinase 1/2 (LATS1/2), leading to increased YAP1 entering the nucleus. circANKRD42 also sponged miR-136-5p to promote the YAP1 translation. Accumulating YAP1 in nucleus bound to TEAD, which initiated the transcription of genes related to mechanical stiffness. Finally, the therapeutic effect of circANKRD42 was evaluated in mice and the association between circANKRD42 and clinicopathological features was analyzed in IPF patients. Our findings supported that circANKRD42 is a promising biomarker and a potential therapeutic target related to cytoskeleton tension for IPF treatment.

Analyses of circRNA and mRNA Profiles in Vogt-Koyanagi-Harada Disease

Recent studies revealed that circular RNAs (circRNAs) are important in numerous biological process and involved in autoimmune diseases. However, their role in Vogt-Koyanagi-Harada (VKH) disease, a classical autoimmune disease, is not yet known. This research aimed to study the expression profile of mRNAs, microRNAs (miRNAs) and circRNAs and investigate the influence of circRNAs on the pathogenesis of VKH disease. We identified circRNAs, miRNAs, and mRNAs expression profiles in CD4⁺ T cells between 4 VKH patients and 3 healthy controls using the whole-transcriptome sequencing (RNA-seq) technique. We discovered that a total of 5088 mRNAs, 451 circRNAs and 433 miRNAs were differently expressed. The GO and KEGG pathway enrichment analyses were performed for significantly differentially expressed circRNAs and mRNAs. GSEA was conducted for all mRNAs. The functional enrichment suggested that the inflammatory response, the adaptive immune response, NF-kappa B signaling pathway, Th17 cell differentiation, Th1 and Th2 cell differentiation and T cell receptor signaling pathway were associated with VKH disease. In addition, based on the immune-related genes we screened, the circRNA-miRNA-mRNA ceRNA network was analyzed and constructed. Ten differently expressed mRNAs (LAT, ZAP70, ITK, ICOS, RASGRP1, PAG1, PLCG1, PRKCQ, LCK, CARD11) and 5 differently expressed circRNAs (hsa_circ_0033144, hsa_circ_0000233, hsa_circ_0000396, hsa_circ_0001924, hsa_circ_0001320) were selected to be validated by Real-time qPCR (RT-qPCR). The results of RT-qPCR turned out to be consistent with RNA-seq data. Further analysis showed that hsa_circ_0001320 and hsa_circ_0001924 may serve as crucial candidate marker genes of VKH disease. These results reveal that circRNAs may have a crucial immunomodulatory function in the pathophysiological process of VKH disease.

Identifying a novel IRF3/circUHRF1/miR-1306-5p/ARL4C axis in pancreatic ductal adenocarcinoma progression

Pancreatic ductal adenocarcinoma (PDAC) is considered one most aggressive and lethal cancer types worldwide. While its underlying mechanisms are still poorly understood. CircRNAs play essential roles in various biological progression, including PDAC. Here, our results found that circUHRF1 was highly expressed in PDAC tumor tissues compared with normal tissues. Next, Cell or animal models were constructed, CCK-8, cell colony, EdU, flow cytometry assay, transwell migration, and Western blot assays were applied. CircUHRF1 knockdown influenced PDAC cell proliferation, apoptosis, migration and EMT level in vitro, and tumor growth in vivo. Subsequently, bioinformatics analysis, AGO2-RIP, RNA pull-down, and dual-luciferase reporter assays were used to explore the downstream targets in PDAC progression. Our findings suggest that circUHRF1 regulated ARL4C expression to promote PDAC progression through sponging miR-1306-5p. The role of miR-1306-5p in PDAC cellular progression has been elucidated, and the expression association between miR-1306-5p and circUHRF1 or ARL4C in PDAC tissues was analyzed. Furthermore, circUHRF1 expression in PDAC cells could be transcriptionally regulated by IRF3. Collectively, our study demonstrated the role of IRF3/circUHRF1/miR-1306-5p/ARL4C axis in PDAC progression. Our results suggest that circUHRF1 is one promising diagnosis or therapeutic target for PDAC management.Abbreviations : CircRNA; Circular RNAPDAC; pancreatic ductal adenocarcinomaUHRF1; Ubiquitin-like with PHD and RING finger domain 1ARL4C; ADP Ribosylation Factor Like GTPase 4CRIP; RNA immunoprecipitationEDU; 5-Ethynyl-2'-deoxyuridineEMT; epithelial to mesenchymal transitionAGO2; Argonaute RISC Catalytic Component 2CCK8; Cell counting Kit-8IRF3; Interferon Regulatory Factor 3.

Circ_LPAR3 promotes the progression of oral squamous cell carcinoma (OSCC)

BACKGROUND

circ_LPAR3 is an oncogene in esophageal squamous cell carcinoma. However, its role in oral squamous cell carcinoma (OSCC) is unknown.

PURPOSE

To reveal the functions of circ_LPAR3 in OSCC.

METHODS

Online bioinformatic analysis was performed to disclose the differential expression of circ_LPAR3, VEGFC, AKT1 in OSCC and also the target predictions of miR-513b-5p. Transfection was applied in OSCC cells. RT-qPCR was used to detect the RNA expression and western blot to measure the proteins, VEGFC and phosphor-AKT1 (ser473, p-AKT1). CCK8 kit was used for viability detection and Flow cytometry for apoptosis evaluation. RNA pull-down and luciferase reporter methods were used to validate the binding sites to miR-513b-5p on circ_LPAR3, VEGFC and AKT1. OSCC mice models were established to further unveil the functions of circ_LPAR3 in OSCC in vivo. H&E staining and immunohistochemistry (CD34, VEGFC and p-AKT1) were further applied to analyze the pathological changes in association with circ_LPAR3 downregulation.

RESULTS

circ_LPAR3 was upregulated in OSCC. Its knockdown in cells could decrease cell survival and mobility and in mice model, could inhibit the tumor growth and angiogenesis. Circ_LPAR3 promoted VEGFC and AKT1 activity by sponging miR-513b-5p in OSCC cells.

CONCLUSION

Knockdown of circ_LPAR3 could inhibit the OSCC progression by sponging miR-513b-5p and activating VEGFC and AKT1.

Novel circular RNA circATRNL1 accelerates the osteosarcoma aerobic glycolysis through targeting miR-409-3p/LDHA

In recent researches, circular RNAs (circRNAs) have been shown to exert critical functions in osteosarcoma biology. Nevertheless, the contribution of circRNAs to osteosarcoma remains largely unclear. Results indicated that expression of circATRNL1 was higher in osteosarcoma tissues and cells. The high-expression of circATRNL1 was significantly correlated with aggressive features and acted as an independent risk factor for osteosarcoma patients' overall survival. Functionally, our findings demonstrate that circATRNL1 promotes the osteosarcoma aerobic glycolysis in vitro. Mechanistically, circATRNL1 up-regulated the expression level of LDHA, which was also targeted by miR-409-3p. Therefore, circATRNL1 exerted the accelerative roles of osteosarcoma aerobic glycolysis through miR-409-3p/LDHA axis. In conclusion, circATRNL1 promoted osteosarcoma progression by enhancing glycolysis via circATRNL1/miR-409-3p/LDHA axis, which may inspire a novel therapeutic target for osteosarcoma.

Circular RNA Mitochondrial Translation Optimization 1 homologue (CircMTO1) induced by Zinc Finger Protein 460 (ZNF460) promotes oral squamous cell carcinoma progression through the microRNA miR-320a / Alpha Thalassemia/Mental Retardation, X-linked (ATRX) axis

Oral squamous cell carcinoma (OSCC) is one of the most common cancer types of head and neck cancer, accounting for 95% of all cases. However, the mechanisms underlying the pathogenesis of OSCC remain unclear. Circular RNA (CircRNA) has been extensively studied in the past decades and is a promising direction for the development of OSCC therapeutic targets. In this study, we aimed to investigate the role of circMTO1 in OSCC progression. First, we validated the characterization and expression of circMTO1 in OSCC. It was found that circMTO1 was upregulated in OSCC tumor tissues and cells. Subsequently, we conducted biological experiments. It was found that circMTO1 knockdown inhibited OSCC cell proliferation, migration, and invasion. Furthermore, we conducted a series of experiments to elucidate the underlying mechanisms. A novel circMTO1/miR-320a/ATRX axis was identified. Our results suggest that circMTO1 modulates ATRX expression to accelerate OSCC progression by sponging miR-320a. Moreover, we found that circMTO1 expression in OSCC was transcriptionally regulated by Zinc Finger Protein 460 (ZNF460). Our study showed a novel ZNF460/circMTO1/miR-320a/ATRX signaling in OSCC development.

Suppression of circ_0008932 inhibits tumor growth and metastasis in osteosarcoma by targeting miR-145-5p

Osteosarcoma (OS) is a common type of primary malignant tumor. Although the pathogenesis of OS has been extensively studied, the underlying molecular mechanisms have remained to be fully elucidated. Accumulating evidence has revealed that dysregulation of various circular RNAs (circRNAs) is associated with tumorigenesis and recent studies have indicated that circRNA circ_0008932 is aberrantly expressed in tumors. In the present study, the expression and detailed function of circ_0008932 in OS were elucidated. The levels of circ_0008932 in OS samples and cell lines were examined using reverse transcription-quantitative PCR. A cell model with circ_0008932 knockdown was generated using specific small interfering RNA (si-circ_0008932). Cell viability was determined by a Cell Counting Kit-8 assay, the cell migratory/invasive capacity was evaluated using Transwell assays and cell apoptosis was assessed by flow cytometry. The results suggested that circ_0008932 was upregulated in most primary OS tumors, suggesting that circ_0008932 is associated with the development of OS. In the in vitro assays, si-circ_0008932 inhibited the proliferation, migration and invasion of OS cells, while apoptosis was promoted. A luciferase reporter assay revealed that circ_0008932 may downregulate microRNA (miR)-145-5p through direct binding. Furthermore, the expression of miR-145-5p was negatively correlated with circ_0008932 levels in OS specimens. In addition, further functional studies indicated that miR-145-5p inhibitors eliminated the effects caused by si-circ_0008932 in OS cells. In comparison, the changes in the biological behavior of OS cells transfected with si-circ_0008932 were enhanced by miR-145-5p. In summary, circ_0008932 may be a novel oncogenic factor during the progression and development of OS by targeting miR-145-5p; more importantly, circ_0008932 may be a potential therapeutic target for OS.

The power and the promise of circRNAs for cancer precision medicine with functional diagnostics and prognostic prediction

Circular RNA (circRNA) is a large class of covalently closed circular RNA. As a member of competitive endogenous RNA (ceRNA), it participates in the regulation of circRNA-miRNA-mRNA network and plays an important role in the regulation of physiology and pathology. CircRNA is produced by the reverse splicing of exon, intron or both, forming exon or intron circRNA. Studies have shown that circRNA is a ubiquitous molecule, which exceeds the linear mRNA distributed in human cells. Because of its covalent closed-loop structure, circRNA is resistant to RNase R, which is more stable than linear mRNA; circRNA is highly conserved in different species. It was found that circRNA competitively adsorbs miRNA, as a miRNA sponge, to involve in the expression regulation of a variety of genes and plays an important role in tumor development, invasion, metastasis and other processes. These molecules offer new potential opportunities for therapeutic intervention and serve as biomarkers for diagnosis. In this paper, the origin, characteristics and functions of circRNA and its role in tumor development, invasion and metastasis, diagnosis and prognosis are reviewed.

Knockdown of lncRNA DLEU1 inhibits the tumorigenesis of oral squamous cell carcinoma via regulation of miR‑149‑5p/CDK6 axis

Oral squamous cell carcinoma (OSCC) is a frequent malignant tumor worldwide. Long non-coding RNAs (lncRNAs) are known to play key roles in different types of cancer, including OSCC. It was previously reported that lncRNA deleted in lymphocytic leukemia 1 (DLEU1) is notably upregulated in OSCC; however, the role of DLEU1 in OSCC remains unclear. Gene and protein expression levels in OSCC cells were detected by reverse transcription-quantitative PCR and western blotting, respectively, in the present study. A Transwell assay was performed to measure cell migration and invasion. Flow cytometry was used to detect cell apoptosis, and the dual-luciferase reporter assay was applied to confirm the interaction between DLEU1, microRNA (miR)-149-5p and CDK6 in OSCC cells. DLEU1 expression was negatively associated with the survival rate of patients with OSCC. In addition, silencing of DLEU1 notably inhibited the proliferation of OSCC cells by inducing apoptosis. Meanwhile, DLEU1 directly bound to miR-149-5p, and CDK6 was found to be the direct target of miR-149-5p. Furthermore, DLEU1 knockdown-induced inhibition of OSCC cell proliferation was significantly reversed by the miR-149-5p antagomir. Knockdown of lncRNA DLEU1 reversed the proliferation of OSCC cells via regulation of the miR-149-5p/CDK6 axis. Thus, DLEU1 may serve as a novel target for treating OSCC.