CiRS-7 targeting miR-7 modulates the progression of non-small cell lung cancer in a manner dependent on NF-κB signalling

Epigenetic modifications in early stage lung cancer: pathogenesis, biomarkers, and early diagnosis

The integration of liquid biopsy with epigenetic markers offers significant potential for early lung cancer detection and personalized treatment. Epigenetic alterations, including DNA methylation, histone modifications, and noncoding RNA changes, often precede genetic mutations and are critical in cancer progression. In this study, we explore how liquid biopsy, combined with epigenetic markers, can provide early detection of lung cancer, potentially predicting onset up to 4 years before clinical diagnosis. We discuss the challenges of targeting epigenetic regulators, which could disrupt cellular balance if overexploited, and the need for maintaining key gene expressions in therapeutic applications. This review highlights the promise and challenges of using liquid biopsy and epigenetic markers for early-stage lung cancer diagnosis, with a focus on optimizing treatment strategies for personalized and precision medicine.

Circular RNAs as key regulators in cancer hallmarks: New progress and therapeutic opportunities

Circular RNAs (circRNAs) have emerged as critical regulators in cancer biology, contributing to various cancer hallmarks, including cell proliferation, apoptosis, metastasis, and drug resistance. Defined by their covalently closed loop structure, circRNAs possess unique characteristics like high stability, abundance, and tissue-specific expression. These non-coding RNAs function through mechanisms such as miRNA sponging, interactions with RNA-binding proteins (RBPs), and modulating transcription and splicing. Advances in RNA sequencing and bioinformatics tools have enabled the identification and functional annotation of circRNAs across different cancer types. Clinically, circRNAs demonstrate high specificity and sensitivity in samples, offering potential as diagnostic and prognostic biomarkers. Additionally, therapeutic strategies involving circRNA mimics, inhibitors, and delivery systems are under investigation. However, their precise mechanisms remain unclear, and more clinical evidence is needed regarding their roles in cancer hallmarks. Understanding circRNAs will pave the way for novel diagnostic and therapeutic approaches, potentially improving patient outcomes.

Molecular mechanism of Gancao Xiexin Decoction regulating EMT and suppressing hepatic metastasis of gastric cancer via the TGF-β1/SMAD pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Gastric cancer (GC) is a highly malignant tumor of the digestive tract, posing a significant menace to human health. Gancao Xiexin Decoction (GCXXD), being a traditional Chinese medicine (TCM), has a good effect on inhibiting the proliferation and metastasis of GC. However, its mechanisms still need further investigation.

AIM OF STUDY

To investigate the mechanism by which GCXXD inhibits GC metastasis through network pharmacology, and to verify through in vivo and in vitro experiments.

MATERIALS AND METHODS

The TCMSP and GEO databases, in combination with UPLC-MS/MS techniques, were employed to identify the hub genes, active ingredients, and critical pathways of GCXXD in the treatment of GC. Subsequently, molecular docking was conducted on both the hub genes and the core components. Finally, based on the results of the bioinformatics analysis, the role of GCXXD in inhibiting liver metastasis of GC was elucidated through in vivo and in vitro experiments, including scratch assays, Transwell assays, HE staining, immunohistochemistry, in vivo live imaging, qRT-PCR, and Western blotting.

RESULTS

Utilizing UPLC-MS/MS and network pharmacology, we identified 20 active ingredients and 5 hub targets in the treatment of GC by GCXXD. Through KEGG analyses, GCXXD treatment of GC could through the TGF-beta pathway. In vivo and in vitro experiments, GCXXD downregulated the mRNA and protein expression level of hub genes involved in the TGF-β1/SMAD pathway and the EMT process. Additionally, GCXXD significantly reduced the incidence of liver metastases in GC.

CONCLUSION

GCXXD inhibited EMT via blocking the TGF-β1/SMAD pathway, which suppressed GC cell growth and liver metastasis. This study provides data to support the treatment of liver metastasis in GC with TCM and holds significant importance for the research and development of new anticancer drugs.

The prognosis of ciRS-7 and circHIPK3 in pan-cancer: a mini-review and meta-analysis

BACKGROUND

Circular RNAs (circRNAs) are increasingly recognized for their potential as cancer biomarkers. Although various studies have investigated the biological function of ciRS-7 and circHIPK3 in malignant tumors, their prognostic value in pan-cancer has not been systematically analyzed.

METHODS

We systematically searched the PubMed, Web of Science, and Cochrane Library databases from January 1, 1990, to October 14, 2024. The impact of ciRS-7 or circHIPK3 on prognostic outcomes, including overall survival (OS) and disease-free survival (DFS), was assessed by pooled hazard ratios (HR). The association between CiRS-7 or circHIPK3 and clinical features was evaluated using odds ratios (OR). The Data analysis was conducted using Review Manager 5.4.

RESULTS

For most cancers, our meta-analysis of 14 studies (N = 2140) and 15 studies (N = 1045) showed that high ciRS-7 and circHIPK3 were associated with worse OS. Pooled analysis of 5 studies (N = 421) and 2 studies (N = 248) indicated that high ciRS-7 and circHIPK3 were also associated with shorter DFS. Additionally, high ciRS-7 and circHIPK3 expression were associated with worse histological grade, higher TNM stage, larger tumor size, more lymph node and distant metastasis.

CONCLUSION

High ciRS-7 and circHIPK3 were significantly associated with poor prognosis and advanced clinical features in most cancers, suggesting their potential as prognostic biomarkers.

Circular RNAs: Novel Players in Cancer Mechanisms and Therapeutic Strategies

Circular RNAs (circRNAs) are a novel class of noncoding RNAs that have emerged as pivotal players in gene regulation. Our understanding of circRNAs has greatly expanded over the last decade, with studies elucidating their biology and exploring their therapeutic applications. In this review, we provide an overview of the current understanding of circRNA biogenesis, outline their mechanisms of action in cancer, and assess their clinical potential as biomarkers. Furthermore, we discuss circRNAs as a potential therapeutic strategy, including recent advances in circRNA production and translation, along with proof-of-concept preclinical studies of cancer vaccines.

Circular RNA: The evolving potential in the disease world

Circular RNAs (circRNAs), a new star of noncoding RNAs, are a group of endogenous RNAs that form a covalently closed circle and occur widely in the mammalian genome. Most circRNAs are conserved throughout species and frequently show stage-specific expression during various stages of tissue development. CircRNAs were a mystery discovery, as they were initially believed to be a product of splicing errors; however, subsequent research has shown that circRNAs can perform various functions and help in the regulation of splicing and transcription, including playing a role as microRNA (miRNA) sponges. With the application of high throughput next-generation technologies, circRNA hotspots were discovered. There are emerging indications that explain the association of circRNAs with human diseases, like cancers, developmental disorders, and inflammation, and circRNAs may be a new potential biomarker for the diagnosis and treatment outcome of various diseases, including cancer. After the discoveries of miRNAs and long noncoding RNAs, circRNAs are now acting as a novel research entity of interest in the field of RNA disease biology. In this review, we aim to focus on major updates on the biogeny and metabolism of circRNAs, along with their possible/established roles in major human diseases.

The role of circular RNAs (circRNAs) as a prognostic factor in lung cancer: a meta-analysis

BACKGROUND

Lung cancer is a leading cause of cancer-related death worldwide. Among various histological types of lung cancer, majority are non-small cell lung cancer (NSCLC) which account for > 80%. Circular RNAs (circRNAs) are widely expressed in various cancers including lung cancer and implicated in tumourigenesis and cancer progression. This study aimed to systematically evaluate the prognostic values of circRNAs in lung cancer.

METHODS

A systematic literature search was done in PubMed, Embase, and MEDLINE databases to select the eligible studies which reported the association between the expression of circRNAs and overall survival (OS) or disease-free survival (DFS) in histopathologically diagnosed lung cancer patients. The pooled hazard ratio (HR) and 95% confidence interval (CI) were assessed to determine the prognostic significance of circRNAs.

RESULTS

A total of 43 studies were eligible for this meta-analysis (MA). 39 different types of circRNAs were reported: 28 showing upregulating and 11 showing downregulating action in lung cancer. High expression of circRNAs with upregulating action in lung cancer was associated with worse prognosis and poor OS (HR 1.93, 95% CI [1.61-2.33], p < 0.00001). High expression of circRNAs with downregulating action in lung cancer was associated with favorable OS and prognosis (HR 0.73, 95% CI [0.58-0.94], p = 0.01). However, there was no statistically significant association between high and low expression of both upregulating and downregulating circRNAs and DFS (HR 1.44, 95% CI [0.92-2.24], p = 0.11).

CONCLUSIONS

This MA confirmed the pivotal role of circRNAs as important prognostic biomarkers for lung cancer, especially NSCLC. High expression of upregulating circRNAs is associated with poor prognosis; however, high expression of downregulating circRNAs is associated with favorable prognosis. Therefore, downregulatory action of circRNAs should be considered a promising treatment in the management of lung cancer, especially NSCLC.

ciRS-7 circular RNA overexpression in plasma cells is a promising molecular biomarker of unfavorable prognosis in multiple myeloma

Several non-coding RNAs are known to be associated with the pathobiology and progression of multiple myeloma (MM). ciRS-7 (also known as CDR1-AS), a key oncogenic circular RNA (circRNA) that sponges miR-7-5p and other cancer-related microRNAs, was recently found to be downregulated in malignant plasma cells resistant to immunomodulatory drugs. Considering that various circRNAs have a strong potential as molecular biomarkers, we aimed to investigate the expression of ciRS-7 in plasma cell disorders, assess its prognostic importance in MM, and compare these findings with those of individuals with smoldering MM (SMM) and monoclonal gammopathy of unknown significance (MGUS). This study included 171 patients (110 newly diagnosed MM, 34 SMM, and 27 MGUS cases), from which bone marrow aspirate samples were collected for CD138+ plasma cell selection. Total RNA was reversely transcribed using random hexamer primers, and the expression levels of ciRS-7 were quantified using an in-house-developed protocol that includes pre-amplification and real-time quantitative polymerase chain reaction. ciRS-7 levels were found to significantly differ among CD138+ plasma cells of MM, SMM, and MGUS patients. ROC analysis indicated that ciRS-7 expression effectively distinguishes between MM and SMM patients. Moreover, high levels of ciRS-7 were associated with unfavorable prognosis in MM, independently of MM patients' age and Revised International Staging System stage. Additionally, in silico analysis predicted the binding of 85 microRNAs to ciRS-7. In conclusion, this study provides novel insights into the role of ciRS-7 as a promising molecular marker able to distinguish MM from SMM and predict prognosis in MM.

Circular RNAs in tuberculosis and lung cancer

This review signifies the role of circular RNAs (circRNAs) in tuberculosis (TB) and lung cancer (LC), focusing on pathogenesis, diagnosis, and treatment. CircRNAs, a newly discovered type of non-coding RNA, have emerged as key regulators of gene expression and promising biomarkers in various bodily fluids due to their stability. The current review discusses circRNA biogenesis, highlighting their RNase-R resistance due to their loop forming structure, making them effective biomarkers. It details their roles in gene regulation, including splicing, transcription control, and miRNA interactions, and their impact on cellular processes and diseases. For LC, the review identifies circRNA dysregulation affecting cell growth, motility, and survival, and their potential as therapeutic targets and biomarkers. In TB, it addresses circRNAs' influence on host anti-TB immune responses, proposing their use as early diagnostic markers. The paper also explores the interplay between TB and LC, emphasizing circRNAs as dual biosignatures, and the necessity for differential diagnosis. It concludes that no single circRNA biomarker is universally applicable for both TB and LC. Ultimately, the review highlights the pivotal role of circRNAs in TB and LC, encouraging further research in biomarker identification and therapeutic development concomitant for both diseases.

Non-coding RNAs as therapeutic targets in cancer and its clinical application

Cancer genomics has led to the discovery of numerous oncogenes and tumor suppressor genes that play critical roles in cancer development and progression. Oncogenes promote cell growth and proliferation, whereas tumor suppressor genes inhibit cell growth and division. The dysregulation of these genes can lead to the development of cancer. Recent studies have focused on non-coding RNAs (ncRNAs), including circular RNA (circRNA), long non-coding RNA (lncRNA), and microRNA (miRNA), as therapeutic targets for cancer. In this article, we discuss the oncogenes and tumor suppressor genes of ncRNAs associated with different types of cancer and their potential as therapeutic targets. Here, we highlight the mechanisms of action of these genes and their clinical applications in cancer treatment. Understanding the molecular mechanisms underlying cancer development and identifying specific therapeutic targets are essential steps towards the development of effective cancer treatments.

Promoter A1312C mutation leads to microRNA-7 downregulation in human non-small cell lung cancer

MicroRNA-7 (miRNA-7, miR-7) is a unique class of tumor suppressors, plays an important role in various physiological and pathological processes including human non-small cell lung cancer (NSCLC). In previous works, we revealed that miR-7 could regulate the growth and metastasis of human NSCLC cells. However, the mechanism of dysregulated miR-7 expression in NSCLC remains to be further elucidated. In this study, based on clinical sample analysis, we found that the downregulated expression of miR-7 was dominantly attributed to the decreased level of pri-miR-7-2 in human NSCLC. Furthermore, there were four site mutations in the miR-7-2 promoter sequence. Notably, among these four sites, mutation at -1312 locus (A → C, termed as A1312C mutation) was dominate, and A1312C mutation further led to decreased expression of miR-7 in human NSCLC cells, accompanied with elevated transduction of NDUFA4/ERK/AKT signaling pathway. Mechanistically, homeobox A5 (HOXA5) is the key transcription factors regulating miR-7 expression in NSCLC. A1312C mutation impairs HOXA5 binding, thereby reducing the transcriptional activity of miR-7-2 promoter, resulting in downregulation of miR-7 expression. Together, these data may provide new insights into the dysregulation of specific miRNA expression in NSCLC and ultimately prove to be helpful in the diagnostic, prognostic, and therapeutic strategies against NSCLC.

Emerging roles of circular RNAs in the invasion and metastasis of head and neck cancer: Possible functions and mechanisms

Head and neck cancer (HNC) is the seventh most prevalent malignancy worldwide in 2020. Cancer metastasis is the main cause of poor prognosis in HNC patients. Recently, circular RNAs (circRNAs), initially thought to have no biological function, are attracting increasing attention, and their crucial roles in mediating HNC metastasis are being extensively investigated. Existing studies have shown that circRNAs primarily function through miRNA sponges, transcriptional regulation, interacting with RNA-binding proteins (RBPs) and as translation templates. Among these functions, the function of miRNA sponge is the most prominent. In this review, we summarized the reported circRNAs involved in HNC metastasis, aiming to elucidate the regulatory relationship between circRNAs and HNC metastasis. Furthermore, we summarized the latest advances in the epidemiological information of HNC metastasis and the tumor metastasis theories, the biogenesis, characterization and functional mechanisms of circRNAs, and their potential clinical applications. Although the research on circRNAs is still in its infancy, circRNAs are expected to serve as prognostic markers and effective therapeutic targets to inhibit HNC metastasis and significantly improve the prognosis of HNC patients.

The role of CDR1as/ciRS-7 in cardio-cerebrovascular diseases

Cerebellar degeneration-related protein 1 antisense RNA (CDR1as), also known as ciRS-7, is a circular natural antisense transcript of CDR1. It is a widely studied and powerful representative of circular RNAs. Based on its widely reported role in cancer, CDR1as is considered one of the most promising biomarkers for diagnosing and treating tumours. However, some recent studies have extensively focused on its regulatory role in cardio-cerebrovascular diseases instead of in tumours. Studies have shown that CDR1as plays a unique role in the occurrence of cardio-cerebrovascular diseases; thus, it may be a potential target for preventing and treating cardio-cerebrovascular diseases. Furthermore, CDR1as has also been found to be related to signal transduction pathways related to inflammatory response, oxidative stress, etc., which may reveal its potential mechanism in cardio-cerebrovascular diseases. However, there is no literature to summarize the role and possible mechanism of CDR1as in cardio-cerebrovascular diseases. Therefore, in the present review, we have comprehensively summarised the latest progress in the biological characteristics, development processes, regulatory mechanisms, and roles of CDR1as in cardio-cerebrovascular diseases, aiming to provide a reference and guidance for future studies.

miR-124 as a Liquid Biopsy Prognostic Biomarker in Small Extracellular Vesicles from NSCLC Patients

Despite advances in non-small cell lung cancer (NSCLC) research, this is still the most common cancer type that has been diagnosed up to date. microRNAs have emerged as useful clinical biomarkers in both tissue and liquid biopsy. However, there are no reliable predictive biomarkers for clinical use. We evaluated the preclinical use of seven candidate miRNAs previously identified by our group. We collected a total of 120 prospective samples from 88 NSCLC patients. miRNA levels were analyzed via qRT-PCR from tissue and blood samples. miR-124 gene target prediction was performed using RNA sequencing data from our group and interrogating data from 2952 NSCLC patients from two public databases. We found higher levels of all seven miRNAs in tissue compared to plasma samples, except for miR-124. Our findings indicate that levels of miR-124, both free-circulating and within exosomes, are increased throughout the progression of the disease, suggesting its potential as a marker of disease progression in both advanced and early stages. Our bioinformatics approach identified KPNA4 and SPOCK1 as potential miR-124 targets in NSCLC. miR-124 levels can be used to identify early-stage NSCLC patients at higher risk of relapse.

CircRNA CDR1as：a novel diagnostic and prognostic biomarker for gastric cancer

BACKGROUND

Circular RNA (circRNA) CDR1as is emerging as a vital tumor regulator. This study aimed to investigate its diagnostic and prognostic value and molecular mechanisms for gastric cancer (GC).

METHODS

CDR1as expression in GC and adjacent normal tissues (n = 82), paired plasma (n = 65) and plasma exosome samples (n = 68) from GC patients and healthy controls were determined by reverse transcription quantitative polymerase chain reaction (RT-qPCR). Correlations between CDR1as level and clinicopathological factors of GC patients were analyzed. Its diagnostic and prognostic value was evaluated by receiver operating characteristic (ROC) curves and Cox regression analysis combined with Kaplan-Meier plots. CDR1as-regulated proteins and signaling pathways were identified by quantitative proteomics and bioinformatic analysis.

RESULTS

CDR1as was downregulated in GC tissues and associated with tumor size and neural invasion. Plasma- and exosome-derived CDR1as was upregulated in GC patients while plasma-derived CDR1as level was related to lymphatic metastasis. Area under ROC curve (AUC) of tissue-, plasma- and exosome-derived CDR1as was 0.782, 0.641, 0.536 while combination of plasma CDR1as, serum CEA and CA19-9 increased AUC to 0.786. Distal metastasis, TNM stage and tissue-derived CDR1as level were independent predictors for overall survival (OS) of patients. MiRNA signaling networks and glycine, serine and threonine metabolism were regulated by CDR1as and HSPE1 might be a key protein.

CONCLUSIONS

CDR1as is a crucial regulator and promising biomarker for GC diagnosis and prognosis.Clinical significanceCDR1as level in tumor tissues and plasma of GC patients was associated with tumor progression. The findings indicate that CDR1as is involved in GC progression and is a potential diagnostic and prognostic biomarker.

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

Aims

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

Materials and Methods

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

Results

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

Conclusion

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

TGF-β signaling promotes cervical cancer metastasis via CDR1as

BACKGROUND

Due to the lack of effective treatment, metastasis is the main cause of cancer related deaths. TGF-β pathway has been reported related to cervical cancer metastasis. However, mechanism is still unclear.

METHODS

After agonist of TGF-β treatment, RNA sequencing revealed the expression profiles of circRNA in cervical cancer. In situ hybridization was used to analysis relationship between CDR1as and prognosis. Real-time PCR, Western blot, RNA interference, Transwell assay, Wound healing assay, RNA pulldown assay and RIP assays were performed in vitro. And in vivo cervical cancer model (including foot pad model and subcutaneous tumor formation) was also performed.

RESULTS

CDR1as was found upregulated obviously following TGF-β activation. In situ hybridization showed CDR1as was positively correlated with lymph node metastasis and shortened survival length. Simultaneously, overexpression of CDR1as promoted cervical cancer metastasis in vitro and in vivo. It was also found that CDR1as could facilitate the orchestration of IGF2BP1 on the mRNA of SLUG and stabilize it from degradation. Silencing IGF2BP1 hampers CDR1as related metastasis in cervical cancer. Additionally, effective CDR1as has been proven to activate TGF-β signaling factors known to promote EMT, including P-Smad2 and P-Smad3.

CONCLUSIONS

Our study proved TGF-β signaling may promote cervical cancer metastasis via CDR1as.

Breviscapine Combined with BMSCs Reduces Aβ Deposition in Rat with Alzheimer's Disease by Regulating Circular RNA ciRS-7

AIMS

This study aimed to clarify that breviscapine combined with bone marrow mesenchymal stem cells (BMSCs) treatment can reduce Aβ deposition in Alzheimer's disease (AD) patients.

BACKGROUND

AD is a common degenerative disease of the central nervous system. Aβ protein deposition in the cerebral cortex and hippocampus causes neuronal peroxidation damage, synaptic dysfunction, neuroinflammation, and nerve cell apoptosis, and ultimately leads to AD.

OBJECTIVE

To investigate whether breviscapine combined with BMSCs treatment can reduce Aβ deposition in AD.

METHODS

The AD rat model was successfully induced by Aβ1-42. The expression of protein and mRNA was detected by western blot and reverse transcription-quantitative PCR (RT-qPCR), respectively.

RESULTS

In AD rat brain tissue, the expression of circular RNA ciRS-7 (ciRS-7), ubiquitin carboxyl-terminal hydrolase L1 (UCHL1), and NF-kappaB p65 was significantly downregulated, and the expression of β-amyloid precursor protein (APP), β-site APPcleaving enzyme 1 (BAEC1), and Aβ was upregulated. The expression of ciRS-7, UCHL1, and p65 was significantly upregulated after breviscapine or BMSCs treatment, and there was increased APP and BAEC1 degradation. Notably, breviscapine combined with BMSCs treatment was more effective than either treatment alone. In SH-SY5Y cells, overexpression of ciRS-7 reduced Aβ deposition by upregulating UCHL1 to degrade APP and BAEC1, but these effects were reversed with inhibition of NF-kB signaling. Finally, knockdown of ciRS-7 elevated Aβ, APP, and BAEC1 expression in each group of rats compared with the control.

CONCLUSION

Breviscapine combined with BMSCs treatment can reduce Aβ deposition in AD rats and promote the degradation of APP and BAEC1 by activating NF-kB to promote UCHL1 expression.

Circular RNA ciRS-7 promotes laryngeal squamous cell carcinoma development by inducing TGM3 hypermethylation via miR-432-5p/DNMT3B axis

OBJECTIVE

This work is to explore the mechanism by which circular RNA ciRS-7 affects laryngeal squamous cell carcinoma (LSCC).

METHODS

ciRS-7 expression in LSCC tissues was detected by qRT-PCR, and the association between ciRS-7 with clinicopathological features of LSCC patients was evaluated. HN-4 and UM-SCC-10A cells were transfected or cotransfected with si-ciRS-7, miR-432-5p inhibitor, LV-DNMT3B or si-TGM3. Then, the viability and aggressive nature of the cells were tested. The binding site between ciRS-7 and miR-432-5p or between miR-432-5p and DNMT3B was predicted and the targeting relationship was identified. The specific binding between ciRS-7 and miR-432-5p was further verified by AGO2 RIP assay. HN-4 cells transfected with si-ciRS-7 was injected into nude mice to induce xenograft tumors.

RESULTS

Higher ciRS-7 expression in LSCC tissues was closely associated with higher clinical stage, and exacerbated infiltration and lymph node metastasis in LSCC patients. Silencing ciRS-7 inhibited LSCC cell viability, epithelial-mesenchymal transition (EMT), and promoted the apoptosis. When miR-432-5p was inhibited or DNMT3B was overexpressed, the growth and EMT of LSCC cells were stimulated despite ciRS-7 silencing. Downregulation of ciRS-7 restrained the growth of xenograft tumors in vivo.

CONCLUSION

ciRS-7 promotes the progression of LSCC through increasing TGM3 methylation via miR-432-5p/DNMT3B axis.

CircRNA has_circ_0017109 promotes lung tumor progression via activation of Wnt/β-catenin signaling due to modulating miR-671-5p/FZD4 axis

INTRODUCTION

Accumulating evidence highlights the critical roles of circular RNAs (circRNAs) in the malignant progression of cancers. In this study, we investigated the expression pattern of a newly identified circRNA (hsa_circ_0017109) in non-small cell lung cancer (NSCLC), and examined its downstream molecular targets.

METHODS

Quantitative real-time PCR (qRT-PCR) and Western blotting (WB) were conducted to quantify gene and protein expression. In vitro functional assays such as colony formation assay, cell counting kit-8 (CCK-8) and flow cytometry were used to study cell proliferation and apoptosis. RNA pull-down assay, luciferase reporter assay and RNA immunoprecipitation were performed to validate molecular interaction. Mouse xenograft model of NSCLC cells was used to assess the role of circ_0017109 in tumorigenesis.

RESULTS

Circ_0017109 was upregulated in NSCLC tumor samples and cells. Silencing circ_0017109 impaired cell proliferation and promoted apoptosis in NSCLC cells, and circ_0017109 knockdown suppressed in vivo tumorigenesis of NSCLC cells in mouse xenograft model. MiR-671-5p was identified as a target of circ_0017109, and circ_0017109 negatively impacted on miR-671-5p expression. MiR-671-5p downregulated FZD4 and dampened the activity of Wnt/β-catenin signaling pathway. Circ_0017109 modulated FZD4 expression by suppressing miR-671-5p activity.

CONCLUSIONS

Elevated circ_0017109 expression promotes tumor progression of NSCLC by modulating miR-671-5p/FZD4/β-catenin axis.

The function and clinical implication of circular RNAs in lung cancer

Lung cancer is the leading cause of cancer-related deaths worldwide. Despite the recent advent of promising new targeted therapies, lung cancer diagnostic strategies still have difficulty in identifying the disease at an early stage. Therefore, the characterizations of more sensible and specific cancer biomarkers have become an important goal for clinicians. Circular RNAs are covalently close, endogenous RNAs without 5' end caps or 3'poly (A) tails and have been characterized by high stability, abundance, and conservation as well as display cell/tissue/developmental stage-specific expressions. Numerous studies have confirmed that circRNAs act as microRNA (miRNA) sponges, RNA-binding protein, and transcriptional regulators; some circRNAs even act as translation templates that participate in multiple pathophysiological processes. Growing evidence have confirmed that circRNAs are involved in the pathogenesis of lung cancers through the regulation of proliferation and invasion, cell cycle, autophagy, apoptosis, stemness, tumor microenvironment, and chemotherapy resistance. Moreover, circRNAs have emerged as potential biomarkers for lung cancer diagnosis and prognosis and targets for developing new treatments. In this review, we will summarize recent progresses in identifying the biogenesis, biological functions, potential mechanisms, and clinical applications of these molecules for lung cancer diagnosis, prognosis, and targeted therapy.

Circular RNAs play roles in regulatory networks of cell signaling pathways in human cancers

AIMS

Circular RNAs (circRNAs) are endogenous covalently closed non-coding RNAs produced by reverse splicing of linear RNA. These molecules are highly expressed in mammalian cells and show cell/tissue-specific expression patterns. They are also significantly dysregulated in various cancers and function as oncogenes or tumor suppressors. Emerging evidence reveals that circRNAs contribute to cancer progression via modulating different cell signaling pathways. Nevertheless, the functional significance of circRNAs in cell signaling pathways regulation is still largely elusive. Considering this, shedding light on the multi-pathway effects of circRNAs may improve our understanding of targeted cancer therapy. Here, we discuss how circRNAs regulate the major cell signaling pathways in human cancers.

MATERIALS AND METHODS

We adopted a systematic search in PubMed using the following MeSH terms: circRNAs, non-coding RNAs, lncRNAs, exosomal circRNAs, cancer, and cell signaling.

KEY FINDINGS

We discussed different roles of circRNAs during tumorigenesis in which circRNAs affect tumor development through activating or inactivating certain cell signaling pathways via molecular interactions using various signaling pathways. We also discussed how crosstalk between circRNAs and lncRNAs modulate tumorigenesis and provides a resource for the identification of cancer therapeutic targets.

SIGNIFICANCE

We here elucidated how circRNAs can modulate different cell signaling pathways and play roles in cancer. This can broaden our horizons toward introducing promising prognostic, diagnostic, and therapeutic targets.

CircLONP2 Accelerates Esophageal Squamous Cell Carcinoma Progression via Direct MiR-27b-3p-ZEB1 Axis

Circular RNAs (circRNAs) are important mediators in esophageal squamous cell carcinoma (ESCC) carcinogenesis. We aim to explore the functions and mechanisms of circLONP2 in ESCC progression. The circLONP2 level was evaluated in ESCC samples and cell lines. The role and mechanisms of circLONP2 in ESCC proliferation and migration were demonstrated in vitro. We found that circLONP2 was upregulated in human ESCC and predicts poor overall survival (OS) and disease-free survival (DFS). CircLONP2 promotes ESCC aggressiveness by directly interacting with miR-27b-3p, thus upregulating the expression levels of its target gene ZEB1 by suppressing miR-27b-3p activity. Therefore, we demonstrated that circLONP2/miR-27b-3p/ZEB1 axis promotes ESCC metastasis via regulating epithelial-to-mesenchymal transition (EMT)-related proteins. CircLONP2 may serve as an oncogenic circRNA and as a prognostic biomarker in ESCC progression.

Circulating ciRS-7 as a potential non-invasive biomarker for epithelial ovarian cancer: An investigative study

Background

Ovarian cancer (OC) is the most common malignant neoplasm of the female reproductive system in developed countries. Early detection, diagnosis and prognosis are particularly important to OC. The potential of circulating circular RNAs (circRNAs) as non-invasive biomarkers of various tumors has been especially described in recent years. The aim of this study was to explore the diagnostic and prognostic value of circulating cirRS-7 in patients with epithelial ovarian cancer (EOC).

Methods

Pre- and postoperative plasma samples from 111 EOC patients (47 cases with FIGO stage IA-IIB and 64 cases with FIGO stage IIB-IV) and healthy female volunteers was collected. Circulating ciRS-7 and hsa-miR-7-5p was analyzed using reverse transcription polymerase chain reaction (qRT-PCR). The diagnostic and prognostic value of circulating cirRS-7 as biomarker was estimated by the Receiver Operating Characteristic (ROC) curve and the area under the curve (AUC) and Kaplan–Meier analysis.

Results

The preoperative expression levels of circulating ciRS-7 were increased in plasma of EOC FIGO stage I-IV patients than in the healthy controls (p < 0.001). However, the expression levels of ciRS-7 in the postoperative period were significantly lower in EOC FIGO stage IIA-IIA patients than healthy controls and EOC FIGO stage IIB-IV patients (p < 0.05, p < 0.001). The AUC of ciRS-7 for diagnosing EOC FIGO stage I-IV patients in pre-and postoperative periods was 0.90, 0.92, 0.84, 0.88, 0.58 and 0.86, respectively. Higher circulating ciRS-7 expression is associated with lymph node invasion, FIGO stage, distant metastasis, and worse overall survival (OS) of patients. Moreover, multivariate Cox analysis showed that higher circulating ciRS-7 was an independent predictor of OS in EOC FIGO stage IIB-IV patients. In addition, in plasma of EOC patients, ciRS-7 negatively correlated with has-miR-7-5p in pre-and postoperative periods (p < 0.001).

Conclusions

Circulating ciRS-7 levels in plasma can be considered a potential candidate biomarker for diagnosing EOC patients. Dysregulation of ciRS-7 may participate in the molecular mechanism of EOC through hsa-miR-7-5p sponging.

CircRNAs in lung cancer- role and clinical application

Lung cancer holds the highest mortality rate among malignancies worldwide. Nevertheless, the potential molecular mechanisms of its tumorigenesis and evolution remain obscure. Circular RNAs (circRNAs), a broad category of covalently closed molecules, follow a malignancy-restricted expression pattern. Leading-edge studies have demonstrated the clinical application prospects of circRNAs in lung cancer. Herein, this review elucidates the biogenesis, biological functions, and pathophysiology of circRNAs. Furthermore, we underscore the forefront of the diagnostic, prognostic, and therapeutic potential of circRNAs in lung cancer as well as discuss the bottleneck that needs to be overcome to translate the basic advances of circRNAs into clinical practice.

Examples of Inverse Comorbidity between Cancer and Neurodegenerative Diseases: A Possible Role for Noncoding RNA

Cancer is one of the most common causes of death; in parallel, the incidence and prevalence of central nervous system diseases are equally high. Among neurodegenerative diseases, Alzheimer's dementia is the most common, while Parkinson's disease (PD) is the second most frequent neurodegenerative disease. There is a significant amount of evidence on the complex biological connection between cancer and neurodegeneration. Noncoding RNAs (ncRNAs) are defined as transcribed nucleotides that perform a variety of regulatory functions. The mechanisms by which ncRNAs exert their functions are numerous and involve every aspect of cellular life. The same ncRNA can act in multiple ways, leading to different outcomes; in fact, a single ncRNA can participate in the pathogenesis of more than one disease-even if these seem very different, as cancer and neurodegenerative disorders are. The ncRNA activates specific pathways leading to one or the other clinical phenotype, sometimes with obvious mechanisms of inverse comorbidity. We aimed to collect from the existing literature examples of inverse comorbidity in which ncRNAs seem to play a key role. We also investigated the example of mir-519a-3p, and one of its target genes Poly (ADP-ribose) polymerase 1, for the inverse comorbidity mechanism between some cancers and PD. We believe it is very important to study the inverse comorbidity relationship between cancer and neurodegenerative diseases because it will help us to better assess these two major areas of human disease.

Circular RNAs in hepatocellular carcinoma: Recent advances

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

The role of lncRNA-mediated ceRNA regulatory networks in pancreatic cancer

Non-coding RNAs (ncRNAs), which occupy the vast majority of human transcripts are known for their inability to encode proteins. NcRNAs consist of a diverse range of RNA species, including long non-coding RNAs (lncRNAs), which have significant meaning for epigenetic modification, post-transcriptional regulation of target genes, molecular interference, etc. The dysregulation of ncRNAs will mediate the pathogenesis of diverse human diseases, like cancer. Pancreatic cancer, as one of the most lethal malignancies in the digestive system that is hard to make a definite diagnosis at an early clinicopathological stage with a miserable prognosis. Therefore, the identification of potential and clinically applicable biomarker is momentous to improve the overall survival rate and positively ameliorate the prognosis of patients with pancreatic carcinoma. LncRNAs as one kind of ncRNAs exert multitudinous biological functions, and act as molecular sponges, relying on microRNA response elements (MREs) to competitively target microRNAs (miRNAs), thereby attenuating the degradation or inhibition of miRNAs to their own downstream protein-coding target genes, also thus regulating the initiation and progression of neoplasms. LncRNAs, which emerge aforementioned function are called competing endogenous RNAs (ceRNAs). Consequently, abundant research of lncRNAs as potential biomarkers is of critical significance for the molecular diagnosis, targeted therapy, as well as prognosis monitoring of pancreatic cancer.

Circ_CDR1as: A circular RNA with roles in the carcinogenesis

Circular RNAs are a group of ancient but recently appreciated transcripts that affect carcinogenesis. An example of cancer-related circular RNAs is circ_CDR1as. It is mostly regarded as an oncogenic circular RNA, yet in bladder cancer and glioma it has the opposite effect. In gastric and ovarian cancer, both roles have been reported for this circular RNA. Circ_CDR1as has regulatory effects on miR-1270/AFP, miR-1287/Raf1, miR-7-5p/KLF4, miR-641/HOXA9, miR-219a-5p/SOX5, miR-7/HOXB13 and miR-876-5p/MAGE-A molecular axes. miR-7 is the most appreciated interacting miRNA with circ_CDR1as, since its interaction with circ_CDR1as has been validated in liver cancer, lung cancer, colorectal cancer, esophageal carcinoma, gastric cancer, pancreatic cancer, thyroid cancer, oral squamous cell carcinoma, nasopharyngeal carcinoma and osteosarcoma. The present article aims at summarization of the role of circ_CDR1as in neoplasms and its application as a biomarker in human cancers.

Biogenesis, functions, and clinical implications of circular RNAs in non-small cell lung cancer

Lung cancer (LC) is the leading cause of cancer-related deaths worldwide, with high morbidity and mortality. Non-small cell lung cancer (NSCLC) is a major pathological type of LC and accounts for more than 80% of all cases. Circular RNAs (circRNAs) are a large class of non-coding RNAs (ncRNAs) with covalently closed-loop structures, a high abundance, and tissue-specific expression patterns. They participate in various pathophysiological processes by regulating complex gene networks involved in proliferation, apoptosis, migration, and epithelial-to-mesenchymal transition (EMT), as well as metastasis. A growing number of studies have revealed that the dysregulation of circRNAs contributes to many aspects of cancer progression, such as its occurrence, metastasis, and recurrence, suggesting their great potential as efficient and specific biomarkers in the diagnosis, prognosis, and therapeutic targeting of NSCLC. In this review, we systematically elucidate the characteristics, biogenesis, and functions of circRNAs and focus on their molecular mechanisms in NSCLC progression. Moreover, we highlight their clinical implications in NSCLC treatment.

Circular RNAs Modulate Cancer Hallmark and Molecular Pathways to Support Cancer Progression and Metastasis

Simple Summary

Circular RNAs (circRNA) are a type of RNA molecule of circular shape that are now being extensively studied due to the important roles they play in different biological processes. In addition, they were also shown to be implicated in disease such as cancer. Cancer is a complex process which is often defined by a combination of specific processes called cancer hallmarks. In this review, we summarize the literature on circRNAs in cancer and classify them as being implicated in specific cancer hallmarks.

Abstract

Circular RNAs (circRNAs) are noncoding products of backsplicing of pre-mRNAs which have been established to possess potent biological functions. Dysregulated circRNA expression has been linked to diseases including different types of cancer. Cancer progression is known to result from the dysregulation of several molecular mechanisms responsible for the maintenance of cellular and tissue homeostasis. The dysregulation of these processes is defined as cancer hallmarks, and the molecular pathways implicated in them are regarded as the targets of therapeutic interference. In this review, we summarize the literature on the investigation of circRNAs implicated in cancer hallmark molecular signaling. First, we present general information on the properties of circRNAs, such as their biogenesis and degradation mechanisms, as well as their basic molecular functions. Subsequently, we summarize the roles of circRNAs in the framework of each cancer hallmark and finally discuss the potential as therapeutic targets.

The Emerging Roles of Circular RNAs in the Chemoresistance of Gastrointestinal Cancer

Gastrointestinal (GI) cancer represents a major global health problem due to its aggressive characteristics and poor prognosis. Despite the progress achieved in the development of treatment regimens, the clinical outcomes and therapeutic responses of patients with GI cancer remain unsatisfactory. Chemoresistance arising throughout the clinical intervention is undoubtedly a critical barrier for the successful treatment of GI cancer. However, the precise mechanisms associated with chemoresistance in GI cancer remain unclear. In the past decade, accumulating evidence has indicated that circular RNAs (circRNAs) play a key role in regulating cancer progression and chemoresistance. Notably, circRNAs function as molecular sponges that sequester microRNAs (miRNAs) and/or proteins, and thus indirectly control the expression of specific genes, which eventually promote or suppress drug resistance in GI cancer. Therefore, circRNAs may represent potential therapeutic targets for overcoming drug resistance in patients with GI cancer. This review comprehensively summarizes the regulatory roles of circRNAs in the development of chemoresistance in different GI cancers, including colorectal cancer, gastric cancer and esophageal cancer, as well as deciphers the underlying mechanisms and key molecules involved. Increasing knowledge of the important functions of circRNAs underlying drug resistance will provide new opportunities for developing efficacious therapeutic strategies against GI cancer.

Emerging noncoding RNAs contained in extracellular vesicles: rising stars as biomarkers in lung cancer liquid biopsy

Lung cancer has a high morbidity and mortality rate, and affected patients have a poor prognosis and low survival. The therapeutic approaches for lung cancer treatment, including surgery, radiotherapy, and chemotherapy, are not completely effective, due to late diagnosis. Although the identification of genetic drivers has contributed to the improvement of lung cancer clinical management, the discovery of new diagnostic and prognostic tools remains a critical issue. Liquid biopsy (LB) represents a minimally invasive approach and practical alternative source to investigate tumor-derived alterations and to facilitate the selection of targeted therapies. LB allows for the testing of different analytes such as circulating tumor cells, extracellular vesicles (EVs), tumor-educated platelets, and cell-free nucleic acids including DNAs, RNAs, and noncoding RNAs (ncRNAs). Several regulatory factors control the key cellular oncogenic pathways involved in cancers. ncRNAs have a wide range of regulatory effects in lung cancers. This review focuses on emerging regulatory ncRNAs, freely circulating in body fluids or shuttled by EVs, such as circular-RNAs, small nucleolar-RNAs, small nuclear-RNAs, and piwi-RNAs, as new biomarkers for early detection, prognosis, and monitoring of therapeutic strategy of lung cancer treatment.

CiRS-7/CDR1as; An oncogenic circular RNA as a potential cancer biomarker

Circular RNAs (circRNAs) as a new class of non-coding RNAs (ncRNAs) play role in gene regulation in multicellular organisms via various interactions with nucleic acids, proteins and particularly microRNAs. They have been found to be involved in a number of biological functions particularly in regulation of cell cycle, and extracellular interactions. Thus, dysregulation of circRNAs is found to be associated with several human diseases and especially numerous types of cancers. ciRS-7 is an example of circRNAs which have been studied in a number of human diseases like neurological diseases, diabetes mellitus, and importantly different malignancies. It has been found to regulate cell proliferation and malignant features in cancer cells. CiRS-7 is upregulated in several cancers and its overexpression promoted malignant phenotype of cancer cells via enhancing cell proliferation, migration, and invasion in vitro and in vivo. As a competing endogenous RNA (ceRNA), ciRS-7 is found to sponge miR-7 as the most common miRNA target in interaction together. Functional analyses show role of ciRS-7 in downregulation of miR-7 and involvement of a series of signaling pathways in turn through them it is believed that ciRS-7 regulates malignant behaviors of cancer cells. Clinical studies demonstrate upregulation of ciRS-7 in cancer tissues compared to their non-cancerous adjacent tissues, correlation with worse clinicopathological features in cancerous patients and an independent prognostic factor. In this review, we have an overview to the role of ciRS-7 in development and progression of cancer and also assess its potentials as a diagnostic and prognostic biomarker in human cancers.

Emerging roles of circular RNAs in neuropathic pain

Neuropathic pain is a major type of chronic pain caused by the disease or injury of the somatosensory nervous system. It afflicts about 10% of the general population with a significant proportion of patients’ refractory to conventional medical treatment. This highlights the importance of a better understanding of the molecular pathogenesis of neuropathic pain so as to drive the development of novel mechanism‐driven therapy. Circular RNAs (circRNAs) are a type of non‐coding, regulatory RNAs that exhibit tissue‐ and disease‐specific expression. An increasing number of studies reported that circRNAs may play pivotal roles in the development of neuropathic pain. In this review, we first summarize circRNA expression profiling studies on neuropathic pain. We also highlight the molecular mechanisms of specific circRNAs (circHIPK3, circAnks1a, ciRS‐7, cZRANB1, circZNF609 and circ_0005075) that play key functional roles in the pathogenesis of neuropathic pain and discuss their potential diagnostic, prognostic, and therapeutic utilization in the clinical management of neuropathic pain.

CircRNAs: a family number of miRNA regulatory transcriptome in laryngeal carcinoma

Laryngeal carcinoma (LC) is a common head and neck cancer, which is the result of mutational changes due to gene dysregulation and etiological factors such as tobacco and smoking. A large number of patients received a poor prognosis due to diagnosis at an advanced stage. This highlights the need for definitive, early, and efficient diagnoses. With rapid development of high‐throughput sequencing, circular RNA (circRNA) has been reported to play a pivotal role in cancer. CircRNA functions as a microRNA (miRNA) sponge in the regulation of mRNA expression, forming circRNA‐miRNA regulatory axis. In this review, we described the axis in LC. The result indicated that CDR1as, hsa_circ_0042823, hsa_circ_0023028, circPARD3, hsa_circ_103862, hsa_circ_0000218, circMYLK, circCORO1C, hsa_circ_100290, circ‐CCND1, hsa_circ_0057481, circFLAN, and circRASSF2 expressed higher in LC, whereas, hsa_circ_0036722 and hsa_circ_0042666 expressed lower. The circRNAs regulated the target genes by sponging miRNAs and contributed to the pathogenesis of LC.

Plasma circRNAs as Biomarkers in Cancer

The incidence and mortality of cancer are increasing each year. At present, the sensitivity and specificity of the blood biomarkers that were used in clinical practice are low, which make the detection rate of cancer decrease. With advances in bioinformatics and technology, some non-coding RNA as biomarkers can be easily detected through some traditional and new technologies. Circular RNAs (circRNAs) are non-coding RNAs, that is, they do not encode proteins, and have important regulatory functions. CircRNAs can remain stable in bodily fluids, such as in saliva, blood, urine, and especially plasma. The difference in the expression of plasma circRNAs between cancer patients and normal people may suggest that plasma circRNAs may play an important role in the occurrence and development of cancer. In this review, we summarized the clinical effect of plasma circRNAs in several high-incidence cancers. CircRNAs may be effective biomarkers for tumour diagnosis, treatment selection and prognosis evaluation.

The Use of circRNAs as Biomarkers of Cancer

CircRNAs are a subclass of lncRNAs that have been found to be abundantly present in a wide range of species, including humans. CircRNAs are generally produced by a noncanonical splicing event called backsplicing that is dependent on the canonical splicing machinery, giving rise to circRNAs classified into three main categories: exonic circRNA, circular intronic RNA, and exon-intron circular RNA. Notably, circRNAs possess functional importance and display their functions through different mechanisms of action including sponging miRNAs, or even being translated into functional proteins. In addition, circRNAs also have great potential as biomarkers, particularly in cancer, thanks to their high stability, tissue type and developmental stage specificity, and their presence in biological fluids, which make them promising candidates as noninvasive biomarkers. In this chapter, we describe the most commonly used techniques for the study of circRNAs as cancer biomarkers, including high-throughput techniques such as RNA-Seq and microarrays, and other methods to analyze the presence of specific circRNAs in patient samples.

Melatonin as a promising modulator of aging related neurodegenerative disorders: Role of microRNAs

One of the host risk factors involved in aging-related diseases is coupled with the reduction of endogenous melatonin (MLT) synthesis in the pineal gland. MLT is considered a well-known pleiotropic regulatory hormone to modulate a multitude of biological processes such as the regulation of circadian rhythm attended by potent anti-oxidant, anti-inflammatory, and anti-cancer properties. It has also been established that the microRNAs family, as non-coding mRNAs regulating post-transcriptional processes, also serve a crucial role to promote MLT-related advantageous effects in both experimental and clinical settings. Moreover, the anti-aging impact of MLT and miRNAs participation jointly are of particular interest, recently. In this review, we aimed to scrutinize recent advances concerning the therapeutic implications of MLT, particularly in the brain tissue in the face of aging. We also assessed the possible interplay between microRNAs and MLT, which could be considered a therapeutic strategy to slow down the aging process in the nervous system.

Downregulated hsa_circ_0036988 promotes proliferation and metastasis in oral squamous cell carcinoma

BACKGROUND

As a novel class of endogenous ncRNAs, Circular RNAs (circRNAs) have been verified to be involved in the carcinogenesis and tumor progression.

OBJECTIVE

This study aimed to investigate the potential function of a candidate circRNA hsa_circ_0036988 in oral squamous cell carcinoma (OSCC).

METHODS

The altered expression of hsa_circ_0036988 was validated by quantitative real-time polymerase chain reaction (qRT-PCR) in OSCC samples and OSCC cell lines. The associations between the levels of hsa_circ_0036988 and the clinicopathological features were statistically analysed. The function of hsa_circ_0036988 in OSCC were evaluated via a series of in vitro experiments by using constructed plasmids or siRNA. Western blotting assays were conducted to evaluate changes in protein expression levels.

RESULTS

Hsa_circ_0036988 was significantly downregulated in OSCC tissues compared with adjacent normal tissues. While low expression of hsa_circ_0036988 was highly correlated with lymph nodes metastasis. Overexpression or knockdown of hsa_circ_0036988 significantly affected the proliferation, migration and invasion of OSCC cells. Furthermore, the altered expression of hsa_circ_0036988 have an impact on the epithelial-to-mesenchymal transition (EMT)-related protein expression levels.

CONCLUSIONS

Our findings indicated that hsa_circ_0036988 may affect cell proliferation, migration and invasion by regulating EMT progress, which might provide a therapeutic strategy for the treatment of OSCC.

Circular RNAs regulate cancer-related signaling pathways and serve as potential diagnostic biomarkers for human cancers

Circular RNAs (circRNAs) are RNAs that have an important role in various pathological processes, including cancer. After the usage of high-throughput RNA sequencing, many circRNAs were found to be differentially expressed in various cancer cell lines and regulate cell signaling pathways by modulating particular gene expressions. Understanding their role in these pathways and what cancers they are found in can set the stage for identifying diagnostic and prognostic biomarkers and therapeutic targets of cancer. This paper will discuss which circRNAs are found in different cancers and what mechanisms they use to upregulate or downregulate certain cellular components.

Circular RNA CDR1as Inhibits the Metastasis of Gastric Cancer through Targeting miR-876-5p/GNG7 Axis

Circular RNA CDR1as has been demonstrated to participate in various cancer progressions as miRNA sponges. The exact underlying mechanisms of CDR1as on gastric cancer (GC) metastasis remain unknown. Here, we found that CDR1as knockdown facilitated GC cell migration and invasion while its overexpression inhibited the migration and invasion abilities of GC cells in vitro and in vivo. Moreover, epithelial-mesenchymal transition- (EMT-) associated proteins and MMP2 and MMP9 were downregulated by CDR1as. Bioinformatics analysis combined with dual-luciferase reporter gene assays, western blot, RT-qPCR analysis, and functional rescue experiments demonstrated that CDR1as served as a miR-876-5p sponge and upregulated the target gene GNG7 expression to suppress GC metastasis. In summary, our findings indicate that CDR1as suppresses GC metastasis through the CDR1as/miR-876-5p/GNG7 axis.

Emerging role of circular RNAs in the pathobiology of lung cancer

Lung cancer is among the leading causes of cancer mortality and incidence in both sexes. Different classes of transcripts have been proposed as molecular markers in this type of cancer. Circular RNAs (circRNAs) are a group of transcripts with circular enclosed and stable configuration. These transcripts are stable in the blood, thus can be used as markers for detection of disorders. Moreover, dysregulation of circRNAs in the affected tissues of patients with different cancers shows their possible roles in the carcinogenesis. Several circRNAs including circPRKC1, circFGFR1, hsa-circ-0020123 and circTP63 have been found to be up-regulated in lung cancer samples. Meanwhile, cir-ITCH, hsa_circ_100395, hsa_circ_0033155, circRNF13, circNOL10, circ-UBR5, circPTK2 and circCRIM1 have been shown to be down-regulated in lung cancer tissues compared with noncancerous counterparts. Finally, prognostic values of circPRKC1, circFGFR1, has-circ-00120123, circTP63, circ_0067934, CDR1as, hsa_circRN_103809 and some other circRNAs have been appraised in lung cancer. In the current manuscript, we describe the impact and utility of circRNAs in the pathology of lung cancer.

Targeting Epigenetics in Lung Cancer

The epigenetic landscape, which in part includes DNA methylation, chromatin organization, histone modifications, and noncoding RNA regulation, greatly contributes to the heterogeneity that makes developing effective therapies for lung cancer challenging. This review will provide an overview of the epigenetic alterations that have been implicated in all aspects of cancer pathogenesis and progression as well as summarize clinical applications for targeting epigenetics in the treatment of lung cancer.

Circular RNAs in Hepatocellular Carcinoma: Emerging Functions to Clinical Significances

Hepatocellular carcinoma (HCC) is the most common primary cancer of the liver and carries high morbidity and mortality. Diagnosing HCC at an early stage is challenging. Therefore, finding new, highly sensitive and specific diagnostic biomarkers for the diagnosis and prognosis of HCC patients is extremely important. Circular RNAs (circRNAs) are a class of non-coding RNAs with covalently closed loop structures. They are characterized by remarkable stability, long half-life, abundance and evolutionary conservation. Recent studies have shown that many circRNAs are expressed aberrantly in HCC tissues and have important regulatory roles during the development and progression of HCC. Hence, circRNAs are promising biomarkers for the diagnosis and prognosis of HCC. This review: (i) summarizes the biogenesis, categories, and functions of circRNAs; (ii) focuses on current progress of dysregulated expression of circRNAs in HCC with regard to regulation of the tumor hallmarks, “stemness” of cancer cells, and immunotherapy; (iii) highlights circRNAs as potential biomarkers and therapeutic targets for HCC; and (iv) discusses some of the challenges, questions and future perspectives of circRNAs research in HCC.

Effect of ciRS-7 expression on clear cell renal cell carcinoma progression

Background

Circular RNA ciRS-7 has been reported to be involved in the progression of various cancers. However, ciRS-7 expression and its role in clear cell renal cell carcinoma (ccRCC) progression remains unclear. This study aimed to investigate the effect of ciRS-7 expression on ccRCC and the related signaling pathway.

Methods

ciRS-7 expression was analyzed using quantitative reverse transcription polymerase chain reaction in 87 pairs of ccRCC and matched adjacent normal tissues. The role of ciRS-7 in ccRCC cell proliferation and invasion was determined using the cell counting kit-8 and invasion assays, respectively. Potential mechanisms underlying the role of ciRS-7 in promoting ccRCC progression were explored by Western blotting. The relationship between the expression of ciRS-7 and features of ccRCC was analyzed by the Chi-square test and progression-free survival was determined using a Kaplan-Meier plot.

Results

ciRS-7 was overexpressed in ccRCC tissues compared with that in matched adjacent normal tissues. In addition, ciRS-7 up-regulation was closely associated with tumor diameter (P = 0.050), clinical stage (P = 0.009), and distant metastasis (P = 0.007). ciRS-7 knockdown in 786O and 769P cells markedly inhibited their proliferative and invasive abilities. In addition, ciRS-7 inhibition reduced phosphorylated epidermal growth factor receptor (p-EGFR) and phosphorylated serine/threonine kinase (p-Akt) levels.

Conclusions

ciRS-7 up-regulation could promote ccRCC cell proliferation and invasion, which may be related with the EGFR/Akt signaling pathway. ciRS-7 might be a potential ccRCC therapeutic target.

Clinicopathological and prognostic significance of circRNAs in lung cancer: A systematic review and meta-analysis

BACKGROUND

Circular RNAs (circRNAs) regulate multiple pathways during lung cancer pathogenesis. Apart from functional significance, many circRNAs have been shown to be associated with clinicopathological characteristics and predict lung cancer prognosis. Our aim is to summarize the expanding knowledge of clinical roles of circRNAs in lung cancer.

METHODS

A thorough search of literature was conducted to identify articles about the correlation between circRNA expression and its prognostic and clinicopathological values. Biological mechanisms were summarized.

RESULTS

This study included 35 original articles and 32 circRNAs with prognostic roles for lung cancer. Increased expression of 25 circRNAs and decreased expression of 7 circRNAs predicted poor prognosis. For non-small cell lung cancer, changes of circRNAs were correlated with tumor size, lymph node metastasis, distant metastasis, tumor node metastasis (TNM) stage, and differentiation, indicating the major function of circRNAs is to promote lung cancer invasion and migration. Particularly, meta-analysis of ciRS-7, hsa_circ_0020123, hsa_circ_0067934 showed increase of the 3 circRNAs was associated with positive lymph node metastasis. Increase of ciRS-7 and hsa_circ_0067934 was also related with advanced TNM stage. The biological effects depend on the general function of circRNA as microRNA sponge.

CONCLUSIONS

CircRNAs have the potential to function as prognostic markers and are associated with lung cancer progression and metastasis.

Regulation of Nuclear Factor-KappaB (NF-κB) signaling pathway by non-coding RNAs in cancer: Inhibiting or promoting carcinogenesis?

The nuclear factor-kappaB (NF-κB) signaling pathway is considered as a potential therapeutic target in cancer therapy. It has been well established that transcription factor NF-κB is involved in regulating physiological and pathological events including inflammation, immune response and differentiation. Increasing evidences suggest that deregulated NF-κB signaling can enhance cancer cell proliferation, metastasis and also mediate radio-as well as chemo-resistance. On the contrary, non-coding RNAs (ncRNAs) have been found to modulate NF-κB signaling pathway under different settings. MicroRNAs (miRNAs) can dually inhibit/induce NF-κB signaling thereby affecting the growth and migration of cancer cells. Furthermore, the response of cancer cells to radiotherapy and chemotherapy may also be regulated by miRNAs. Regulation of NF-κB by miRNAs may be mediated via binding to 3^/-UTR region. Interestingly, anti-tumor compounds can increase the expression of tumor-suppressor miRNAs in inhibiting NF-κB activation and the progression of cancers. Long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) can also effectively modulate NF-κB signaling thus affecting tumorigenesis. It is noteworthy that several studies have demonstrated that lncRNAs and circRNAs can affect miRNAs in targeting NF-κB activation. They can act as competing endogenous RNA (ceRNA) thereby reducing miRNA expression to induce NF-κB activation that can in turn promote cancer progression and malignancy.

Emerging roles of circular RNAs in non‑small cell lung cancer (Review)

Circular RNAs (circRNAs) are a class of novel endogenous transcripts with limited protein‑coding abilities. CircRNAs have been demonstrated to function as critical regulators of tumor development and distant metastasis through binding to microRNAs (miRNAs) and interacting with RNA‑binding proteins, thereby regulating transcription and translation. Emerging evidence has illustrated that certain circRNAs can serve as biomarkers for diagnosis and prognosis of cancer, and/or serve as potential therapeutic targets. Expression of functional circRNAs is commonly dysregulated in cancer and this is correlated with advanced Tumor‑Node‑Metastasis stage, lymph node status, distant metastasis, poor differentiation and shorter overall survival of cancer patients. Recently, an increasing number of studies have shown that circRNAs are closely associated with NSCLC. Functional experiments have revealed that circRNAs are intricately associated with the pathological progression of NSCLC. The present review provides an overview of the regulatory effect of circRNAs in the development and progression of NSCLC, taking into consideration various physiological and pathological processes, such as proliferation, apoptosis, invasion and migration, and their potential value as biomarkers and therapeutic targets.