circEIF4G2 modulates the malignant features of cervical cancer via the miR‑218/HOXA1 pathway

Allicin inhibits the biological activities of cervical cancer cells by suppressing circEIF4G2

Allicin is a safe herbal extract believed to have antitumor effects, which, however, remain unclear. The aim of the present work was to discuss Allicin antitumor effects on cervical cancer using cell experiments. Using Hela and Siha to our research objectives in our study, first step, difference concentration of Allicin (20, 40, and 80 μM) treated Hela and Siha cell lines, and next step, discuss circEIF4G2 effects in Allicin antitumor effects in Hela and Siha cell lines; the cell proliferation and EdU-positive cell number by CCK-8 and EdU staining; cell apoptosis rate by flow cytometry; invasion cell number by transwell assay; wound healing rate by wound healing assay; and relative mRNA and protein levels using qRT-PCR and WB assay. With Allicin supplement, the cell proliferation and EdU-positive cell number were significantly depressed with cell apoptosis rate significantly increasing; invasion cell number and wound healing rate significantly suppressed with circEIF4G2 mRNA expression significantly down-regulation (p < .05, respectively). However, there was no significant difference among Allicin, si-circEIF4G2, and Allicin+si-circEIF4G2 in cell biological activities including cell proliferation, apoptosis, invasion and migration, and relative gene and protein expression. Allicin depresses biological activities of cervical cancer cells through down-regulating circEIF4G2/HOXA1/AKT/mTOR.

Role of HOXA1-4 in the development of genetic and malignant diseases

The HOXA genes, belonging to the HOX family, encompass 11 members (HOXA1-11) and exert critical functions in early embryonic development, as well as various adult processes. Furthermore, dysregulation of HOXA genes is implicated in genetic diseases, heart disease, and various cancers. In this comprehensive overview, we primarily focused on the HOXA1-4 genes and their associated functions and diseases. Emphasis was placed on elucidating the impact of abnormal expression of these genes and highlighting their significance in maintaining optimal health and their involvement in the development of genetic and malignant diseases. Furthermore, we delved into their regulatory mechanisms, functional roles, and underlying biology and explored the therapeutic potential of targeting HOXA1-4 genes for the treatment of malignancies. Additionally, we explored the utility of HOXA1-4 genes as biomarkers for monitoring cancer recurrence and metastasis.

MicroRNA therapeutic targets in neonatal hypoxic-ischemic brain injury: a narrative review

Neonatal hypoxic-ischemic brain injury (HIBI) is a devastating injury resulting from impaired blood flow and oxygen delivery to the brain at or around the time of birth. Despite the use of therapeutic hypothermia, more than one in four survivors suffer from major developmental disabilities-an indication of the critical need for more effective therapies. MicroRNAs (miRNA) have the potential to act as biomarkers and/or therapeutic targets in neonatal HIBI as a step toward improving outcomes in this high-risk population. This review summarizes the current literature around the use of cord blood and postnatal circulating blood miRNA expression for diagnosis or prognosis in human infants with hypoxic-ischemic encephalopathy, as well as animal studies assessing endogenous brain miRNA expression and potential for therapeutic targeting of miRNA expression for neuroprotection. Ultimately, the lack of knowledge regarding brain specificity of circulating miRNAs and the temporal variability in expression currently limit the use of miRNAs as biomarkers. However, given their broad effect profile, ease of administration, and small size allowing for effective blood-brain barrier crossing, miRNAs represent promising therapeutic targets for improving brain injury and reducing developmental impairments in neonates after HIBI. IMPACT: The high morbidity and mortality of neonatal hypoxic-ischemic brain injury (HIBI) despite current therapies demonstrates a need for developing more sensitive biomarkers and superior therapeutic options. MicroRNAs have been evaluated both as biomarkers and therapeutic options after neonatal HIBI. The limited knowledge regarding brain specificity of circulating microRNAs and temporal variability in expression currently limit the use of microRNAs as biomarkers. Future studies comparing the neuroprotective effects of modulating microRNA expression must consider temporal changes in the endogenous expression to determine appropriate timing of therapy, while also optimizing techniques for delivery.

CircEIF4G2 promotes proliferation, migration, and invasion of colon cancer LoVo cells by targeting miR-144-3p

BACKGROUND

Many circular RNAs (circRNAs) are abnormally expressed in colorectal cancer, and they can regulate the expression of their target genes by acting as a miRNA sponge molecule, thereby regulating the biological behavior of colorectal cancer cells; however, the role of circEIF4G2/miR-144-3p in the occurrence and development of colorectal cancer and the underlying mechanism are not yet clear.

AIM

To investigate the effect of circEIF4G2/miR-144-3p on the proliferation, migration, and invasion of colorectal cancer LoVo cells.

METHODS

Reverse transcription-quantitative polymerase chain reaction was used to detect the expression of circEIF4G2 and miR-144-3p in colorectal cancer tissues. LoVo cells were divided into four groups and transfected with si-NC, si-circEIF4G2, si-circEIF4G2 + anti-miR-NC, and si-circEIF4G2 + anti-miR-144-3p, respectively. Dual luciferase reporter assay was performed to analyze the targeting relationship between circEIF4G2 and miR-144-3p. CCK-8 assay and clone formation assay were utilized to monitor the proliferation inhibition rate and clone formation in the four groups, respectively. Transwell assay was used to detect cell migration and invasion, and Western blot analysis was performed to determine E-cadherin and N-cadherin protein expression.

RESULTS

The expression of circEIF4G2 in 51 cases of colorectal cancer tissues increased by ~2.38 times compared with tumor adjacent tissues, and the expression of miR-144-3p decreased by about 0.54 times compared with tumor adjacent tissues (P < 0.05 for both). CircEIF4G2 targets and regulates the expression of miR-144-3p. The proliferation inhibition rate and E-cadherin protein expression in the si-circEIF4G2 group increased compared with those in the si-NC group, while the number of clones, migration, invasion, and the expression level of N-cadherin protein were lower than those of the si-NC group (P < 0.05 for all). The proliferation inhibition rate and E-cadherin protein expression in the si-circEIF4G2 + anti-miR-144-3p group were lower than those of the si-circEIF4G2 + anti-miR-NC group, while the number of clones, migration, invasion, and the expression of N-cadherin protein were higher than those of the si-circEIF4G2+anti-miR-NC group (P < 0.05 for all).

CONCLUSION

Knockdown of circEIF4G2 inhibits cell proliferation, migration, and invasion by targeting miR-144-3p in colorectal cancer LoVo cells.

Competing Endogenous RNA (ceRNA) Networks and Splicing Switches in Cervical Cancer: HPV Oncogenesis, Clinical Significance and Therapeutic Opportunities

Cervical cancer (CC) is the primary cause of female cancer fatalities in low-middle-income countries (LMICs). Persistent infections from the human papillomavirus (HPV) can result in cervical cancer. However, numerous different factors influence the development and progression of cervical cancer. Transcriptomic knowledge of the mechanisms with which HPV causes cervical cancer pathogenesis is growing. Nonetheless, there is an existing gap hindering the development of therapeutic approaches and the improvement of patient outcomes. Alternative splicing allows for the production of numerous RNA transcripts and protein isoforms from a single gene, increasing the transcriptome and protein diversity in eukaryotes. Cancer cells exhibit astounding transcriptome modifications by expressing cancer-specific splicing isoforms. High-risk HPV uses cellular alternative splicing events to produce viral and host splice variants and proteins that drive cancer progression or contribute to distinct cancer hallmarks. Understanding how viruses utilize alternative splicing to drive pathogenesis and tumorigenesis is essential. Although research into the role of miRNAs in tumorigenesis is advancing, the function of other non-coding RNAs, including lncRNA and circRNA, has been understudied. Through their interaction with mRNA, non-coding RNAs form a network of competing endogenous RNAs (ceRNAs), which regulate gene expression and promote cervical cancer development and advancement. The dysregulated expression of non-coding RNAs is an understudied and tangled process that promotes cervical cancer development. This review will present the role of aberrant alternative splicing and immunosuppression events in HPV-mediated cervical tumorigenesis, and ceRNA network regulation in cervical cancer pathogenesis will also be discussed. Furthermore, the therapeutic potential of splicing disruptor drugs in cervical cancer will be deliberated.

Novel Insight of CircRNAs in Cervical Cancer: Potential Biomarkers and Therapeutic Target

Cervical cancer (CC) is a prominent cancer around the globe, with a high incidence, and fatality rate. Numerous recent investigations have shown that various non-coding RNAs are associated with the progression of CC. Circular RNAs, a novel class of non-coding RNAs, have a single chain covalent closed-loop structure and are involved in cell growth and other physiological processes. These dysregulated circRNAs seem to have environment-specific functions. They have been demonstrated in certain studies to have a dual involvement in oncogene production and tumor inhibition in different cell settings. Simultaneously, some evidence indicates that circRNAs are abnormally expressed in CC and contributes to its progression. Thus, the distinctive expression profile of circRNAs is associated with the diagnosis, prognosis, and treatment outcomes of CC. We summarized numerous CC-specific circles and their function in revealing the molecular processes of carcinogenesis and progression in CC in this review. Taken together, these data suggest that circRNA may be used as an early detection biomarker and potential therapeutic target in patients with CC.

Dissecting the Role of Circular RNAs in Sarcomas with Emphasis on Osteosarcomas

Circular RNAs (circRNAs) are single-stranded RNAs generated from exons back-splicing from a single pre-mRNA, forming covalently closed loop structures which lack 5'-3'-polarity or polyadenylated tail. Ongoing research depicts that circRNAs play a pivotal role in tumorigenesis, tumor progression, metastatic potential and chemoresistance by regulating transcription, microRNA (miRNA) sponging, RNA-binding protein interactions, alternative splicing and to a lesser degree, protein coding. Sarcomas are rare malignant tumors stemming from mesenchymal cells. Due to their clinically insidious onset, they often present at advanced stage and their treatment may require aggressive chemotherapeutic or surgical options. This review is mainly focused on the regulatory functions of circRNAs on osteosarcoma progression and their potential role as biomarkers, an area which has prompted lately extensive research. The attributed oncogenic role of circRNAs on other mesenchymal tumors such as Kaposi Sarcoma (KS), Rhabdomyosarcoma (RMS) or Gastrointestinal Stromal Tumors (GISTs) is also described. The involvement of circRNAs on sarcoma oncogenesis and relevant emerging diagnostic, prognostic and therapeutic applications are expected to gain more research interest in the future.

A Comprehensive Overview of circRNAs: Emerging Biomarkers and Potential Therapeutics in Gynecological Cancers

Circular RNA (circRNA) is a highly conserved, stable and abundant non-coding RNA (ncRNA). Also, some circRNAs play an essential part in the progression of human cancers. CircRNA is different from traditional linear RNA. CircRNA has a closed circular structure, so it is resistant to exonuclease-mediated degradation and is more stable than linear RNA. Numerous studies have found that many circRNAs can act as a microRNA (miRNA) sponge, interact with RNA-binding proteins, regulate gene transcription, affect alternative splicing and be translated into proteins. Recently, some studies have also indicated that circRNA participates in the progression of gynecological cancers. In addition, circRNA can act as a promising biomarker for the diagnosis of gynecological tumors. Additionally, they can also play a key role in the prognosis of gynecological tumors. Furthermore, to our delight, circRNA may be a potential therapeutic target in gynecological cancers and widely used in clinical practice. This article reviews the functions and related molecular mechanisms of circRNAs in gynecological tumors, and discusses their potential as biomarkers for diagnostic and prognostic and therapeutic targets for gynecological cancers.

hsa_circ_0101119 facilitates the progression of cervical cancer via an interaction with EIF4A3 to inhibit TCEAL6 expression

Recently, circular RNAs (circRNAs/circs) have attracted increased attention due to their regulatory role in a variety of cancer types. However, the role and molecular mechanisms of circRNAs in cervical cancer (CC) remain unknown. The present study aimed to investigate the function of hsa_ circ_0101119 on CC and its potential mechanisms. The differentially expressed circRNAs associated with CC were screened out using R software, according to the database of Gene Expression Omnibus (GEO). The expression levels of hsa_circ_0101119, eukaryotic initiation factor 4A‑3 (EIF4A3) and transcription elongation factor A‑like 6 (TCEAL6) in CC cells were detected via reverse transcription‑quantitative (RT‑q)PCR, and their expression levels in CC tissues were analyzed based on the database of GEO and the Cancer Genome Atlas. Moreover, the accurate functions of hsa_circ_0101119 and TCEAL6 on the proliferation, apoptosis, migration and invasion of SiHa and HeLa cells was examined using colony formation assay, 5‑ethynyl‑20‑deoxyuridine incorporation assay, flow cytometry and Transwell assay. Next, the underlying mechanisms of hsa_circ_0101119 on CC progression were determined via bioinformatics analysis, RNA immunoprecipitation assay, RNA pull down assay, RT‑qPCR and western blotting. It was found that hsa_circ_0101119 was highly expressed in CC tissues and cells, while TCEAL6 was lowly expressed. Knockdown of hsa_circ_0101119 or TCEAL6 overexpression significantly inhibited the proliferation, migration and invasion of SiHa and HeLa cells, but facilitated apoptosis. It was also demonstrated that hsa_circ_0101119 could recruit EIF4A3 to inhibit TCEAL6 expression in CC. Furthermore, knockdown of TCEAL6 could reverse the effects of silencing hsa_circ_0101119 on the proliferation, apoptosis, migration and invasion of HeLa cells. In conclusion, the present study revealed that hsa_circ_0101119 could facilitate cell proliferation, migration and invasion, and suppress apoptosis in CC via an interaction with EIF4A3 to inhibit TCEAL6 expression, which may provide a potential therapeutic target for CC treatment.

circPTPN22 as a novel biomarker and ceRNA in peripheral blood mononuclear cells of rheumatoid arthritis

The role of circular RNAs (circRNAs) in rheumatoid arthritis (RA) remains to be elucidated. To determine the expression of circRNAs in peripheral blood mononuclear cells (PBMCs) and to identify novel biomarkers for RA and explore their potential effects in RA, the present study conducted high-throughput RNA sequencing to analyze circRNA expression profiles in PBMCs from 4 RA patients and 3 healthy controls (HCs). Reverse transcription-quantitative PCR was used to verify the expression of circPTPN22 in 42 RA patients, 44 HCs and 45 systemic lupus erythematosus (SLE) patients. In addition, bioinformatics analysis and Pearson's correlation test were conducted to assess the correlation of the relationships between circPTPN22 and RA progression. A receiver operating characteristic curve was calculated to evaluate the diagnostic value. Multilevel integrated analysis identified 41 upregulated and 30 downregulated circRNAs in RA patients compared with HCs. circPTPN22 was confirmed to be a common differentially expressed gene in RA and SLE compared with HCs. Area under the curve analysis suggested the diagnostic value of circPTPN22 expression to distinguish RA patients from both HCs and SLE patients. In addition, circPTPN22 levels in RA PBMCs were correlated with RA-IgG, RA-IgM, RA-IgA, anti-cyclic citrullinated peptide (anti-CCP), rheumatoid factor and C reactive protein levels. A total of four putative microRNAs (miRNAs or miRs), namely, hsa-miR-3074-5p, hsa-miR-373-3p, hsa-miR-766-3p and hsa-miR-34c-5p, were screened to be sponged by circPTPN22 via bioinformatics analysis and then experimentally verified to be upregulated in RA PBMCs compared with controls. The data suggested that circPTPN22 might be a novel biomarker for the diagnosis of RA and participate in RA pathogenesis through a sponge mechanism.

The Potential of circRNA as a Novel Diagnostic Biomarker in Cervical Cancer

Cervical cancer is the fourth most common cancer among females worldwide. In spite of advances in detection and treatment, it is still one of the most dangerous gynecological malignancies in the world, especially in developing countries, and seriously threatens human health. Circular RNA (circRNA) is a special new type of endogenous noncoding RNA discovered recently. They form a covalently closed continuous loop and are specifically expressed in the eukaryotic transcriptome. With further understanding of circular RNA, a large number of studies have determined the key regulatory role of circRNA in a variety of diseases, especially cancer (including cervical cancer, liver cancer, and lung cancer). In addition, it has also been found that the abnormal expression of circRNA is related to its pathological characteristics in cervical cancer tissue, which can be used as a potential indicator for early screening and diagnosis of cervical cancer, targeted therapy, and prognosis prediction. This article summarizes the recent research achievements of circRNAs in cervical cancer. We briefly described the abnormal expression of circRNA in cervical cancer and discussed the involvement of circRNA in the occurrence process of cervical cancer by regulating cell proliferation, migration, invasion, and apoptosis. We believe that circRNA has potential value as a biomarker in the diagnosis and prognosis of cervical cancer.

Investigating the Underlying Mechanisms of Circular RNAs and Their Application in Clinical Research of Cervical Cancer

Circular RNAs (circRNAs) are non-coding RNA molecules, and these are differentially expressed in various diseases, including cancer, suggesting that circRNAs can regulate certain diseases. CircRNAs can act as miRNAs sponges, RNA-binding protein (RBP) sponges, and translation regulators, and they can become an important part of the regulation of gene expression. Furthermore, because of their biomedical features in body fluids, such as high abundance, conservation, and stability, circRNAs are seen as potential biomarkers for various cancers. Cervical cancer (CC) is one of the main causes of cancer-related death in women, and there have been a large number of studies that analyze circRNAs as a new object to be evaluated in CC. Therefore, this review, by understanding the role of circRNAs in CC, may create innovative strategies in the future clinical diagnosis, treatment, and prognosis of CC and promote the development of personalized and highly accurate cancer therapy.

The regulation of protein translation and its implications for cancer

In addition to the deregulation of gene transcriptions and post-translational protein modifications, the aberrant translation from mRNAs to proteins plays an important role in the pathogenesis of various cancers. Targeting mRNA translation are expected to become potential approaches for anticancer treatments. Protein translation is affected by many factors including translation initiation factors and RNA-binding proteins. Recently, modifications of mRNAs mainly N6-methyladenine (m⁶A) modification and noncoding RNAs, such as microRNAs and long noncoding RNAs are involved. In this review, we generally summarized the recent advances on the regulation of protein translation by the interplay between mRNA modifications and ncRNAs. By doing so, we hope this review could offer some hints for the development of novel approaches in precision therapy of human cancers.

Circular RNAs: Emerging Role in Cancer Diagnostics and Therapeutics

Circular RNAs (circRNAs) are rapidly coming to the fore as major regulators of gene expression and cellular functions. They elicit their influence via a plethora of diverse molecular mechanisms. It is not surprising that aberrant circRNA expression is common in cancers and they have been implicated in multiple aspects of cancer pathophysiology such as apoptosis, invasion, migration, and proliferation. We summarize the emerging role of circRNAs as biomarkers and therapeutic targets in cancer.

The biological and diagnostic roles of MicroRNAs in meningiomas

MicroRNAs (miRNAs) refer to a class of small endogenous non-coding RNAs that regulate gene expression at the post-transcriptional level. Emerging studies have shown that miRNAs play critical roles in tumorigenesis and cancer progression. However, roles and mechanisms of miRNA dysregulation in the pathogenesis of meningioma are not fully understood. Here, we first reviewed existing research of aberrantly expressed miRNAs identified by high throughput microarray profiling in meningioma. We also explored the potential of miRNA as biomarkers and therapeutic targets for novel treatment paradigms of meningiomas. In addition, we summarized recent researches that focused on the possible mechanisms involved in miRNA-mediate meningioma occurrence and progression. This review provides an overview of miRNA deregulation in meningioma and indicates the potential of miRNAs to be used as biomarkers or novel therapeutic targets.

Elevation in the Expression of circ_0079586 Predicts Poor Prognosis and Accelerates Progression in Glioma via Interactions with the miR-183-5p/MDM4 Signaling Pathway

Purpose

Glioma (GM) usually presents with an aggressive behavior and has a poor survival outcome. The abnormal expression of circular RNAs (circRNAs) has already been detected in GM, and circ_0079586 was found to have an increased expression in GM tumors.

Patients and Methods

We assessed the differences in the expression of circ_0079586 in GM tissues (N=60) and cell lines (N=5) using qRT-PCR. The clinical value of circ_0079586 was measured by Fisher’s exact test and Kaplan–Meier and Cox regression analyses. Circ_0079586 siRNA and vector were transfected into LN229 and U251 cells, respectively, and the transfection was verified by qRT-PCR. Cell growth was evaluated by cell counting kit-8 (CCK-8). Cell apoptosis was measured using flow cytometric assay. Cell metastatic properties were measured by wound scratch and transwell experiments. Subcellular fractionation was used to identify the location of circ_0079586. Dual-luciferase reporter test was utilized to confirm the interaction between miR-183-5p and circ_0079586/MDM4 3ʹ-UTR.

Results

The expression of circ_0079586 was elevated in GM samples and cells and correlated with the clinical severity and unfavorable prognosis of the patients. The elevated expression of circ_0079586 led to an increase in cell growth, migration and invasion but inhibited apoptosis in U251 cells, whereas its down-regulation reversed these effects in the LN229 cells. Mechanistically, we found circ_0079586 to be primarily located in the cytoplasm of GM cells. Furthermore, circ_0079586 could act as a sponge for miR-183-5p and elevate MDM4 expression at the posttranscriptional level.

Conclusion

In summary, circ_0079586 was found to be up-regulated in GM that increased the proliferation, migration and invasion in GM cells via interaction with the miR-183-5p/MDM4 axis. We anticipate that our study would provide newer insights into the mechanism and treatment of GM.

The Expression, Functions and Mechanisms of Circular RNAs in Gynecological Cancers

Circular RNAs (circRNAs) are covalently closed, endogenous non-coding RNAs and certain circRNAs are linked to human tumors. Owing to their circular form, circRNAs are protected from degradation by exonucleases, and therefore, they are more stable than linear RNAs. Many circRNAs have been shown to sponge microRNAs, interact with RNA-binding proteins, regulate gene transcription, and be translated into proteins. Mounting evidence suggests that circRNAs are dysregulated in cancer tissues and can mediate various signaling pathways, thus affecting tumorigenesis, metastasis, and remodeling of the tumor microenvironment. First, we review the characteristics, biogenesis, and biological functions of circRNAs, and describe various mechanistic models of circRNAs. Then, we provide a systematic overview of the functional roles of circRNAs in gynecological cancers. Finally, we describe the potential future applications of circRNAs as biomarkers for prognostic stratification and as therapeutic targets in gynecological cancers. Although the function of most circRNAs remains elusive, some individual circRNAs have biologically relevant functions in cervical cancer, ovarian cancer, and endometrial cancer. Certain circRNAs have the potential to serve as biomarkers and therapeutic targets in gynecological cancers.

Recent advances in the contribution of noncoding RNAs to cisplatin resistance in cervical cancer

Cervical cancer (CC) remains a major disease burden on the female population worldwide. Chemotherapy with cisplatin (cis-diamminedichloroplatinum (II); CDDP) and related drugs are the main treatment option for CC; however, their efficacy is limited by the development of drug resistance. Noncoding RNAs (ncRNAs) have been found to play critical roles in numerous physiological and pathological cellular processes, including drug resistance of cancer cells. In this review, we describe some of the ncRNAs, including miRNAs, lncRNAs and circRNAs, that are involved in the sensitivity/resistance of CC to CDDP-based chemotherapy and discuss their mechanisms of action. We also describe some ncRNAs that could be therapeutic targets to improve the sensitivity of CC to CDDP-based chemotherapy.

hsa_circ_0008285 Facilitates the Progression of Cervical Cancer by Targeting miR-211-5p/SOX4 Axis

Introduction

Emerging evidence has demonstrated that circRNAs are implicated in the progression of cervical cancer (CC). However, the roles and underlying mechanisms of circRNAs remain unclear in CC.

Methods

QRT-PCR was performed to detect hsa_circ_0008285 expression in CC tissues and cell lines. The roles of hsa_circ_0008285 on CC progression were explored by function assays. Next, the underlying mechanisms of hsa_circ_0008285 in CC progression were determined by bioinformatics analysis, dual-luciferase reporter and RIP assays.

Results

In the present study, we identified a new circRNA hsa_circ_0008285, which was significantly up-regulated in CC tissues and cell lines. Loss-of-function assays showed that hsa_circ_0008285 suppression reduced the proliferation and invasion of CC cells in vitro and reduced tumor growth in vivo. In mechanism, bioinformatics analysis, dual-luciferase reporter and RIP assays showed that hsa_circ_0008285 served as a sponge for miR-211-5p in CC. Next, we confirmed that SOX4 served as a target gene for miR-211-5p in CC. Additionally, we revealed that miR-211-5p inhibitors abolished the effects of hsa_circ_0008285 on SOX4 expression in CC cells.

Conclusion

Therefore, our research highlighted that hsa_circ_0008285 promoted CC progression via serving as a ceRNA of miR-211-5p to release SOX4, which might provide a potential therapeutic target for tumor treatment.

CircEIF4G2 Promotes Tumorigenesis and Progression of Osteosarcoma by Sponging miR-218

Circular RNAs (circRNAs) play a key role in regulating the tumorigenesis and development of human cancers, including osteosarcoma (OS). Of note, the molecular mechanism underlying the progression of OS has remained largely unclear. The present study identified that a novel circRNA circEIF4G2 was upregulated in OS tissues and cells. Moreover, we constructed a circEIF4G2-mediated ceRNA network and revealed that circEIF4G2 was involved in regulating multiple cancer pathways, such as the EGFR signaling pathway, the PI3K-Akt signaling pathway, and the ErbB signaling pathway. Loss-of-function assays showed that circEIF4G2 knockdown significantly suppressed OS cell proliferation, migration, and invasion. Mechanically, we found that circEIF4G2 could directly bind to miR-218, and miR-218 mediated the effect of circEIF4G2 knockdown on OS progression. In conclusion, the present study showed that circEIF4G2 could be a potential biomarker for OS.

A potential disease monitoring and prognostic biomarker in cervical cancer patients: The clinical application of circular RNA_0018289

OBJECTIVE

This study aimed to investigate the tumor circular RNA_0018289 (circ_0018289) expression and its correlation with clinical characteristics as well as survival profiles in cervical cancer patients.

METHODS

A hundred and ninety-two cervical cancer patients who received surgical resection were recruited in this prospective study. Tumor tissue and paired adjacent tissue were obtained during the surgery, in which circ_0018289 expression was detected by reverse transcription quantitative polymerase chain reaction. Disease-free survival (DFS) and overall survival (OS) were recorded.

RESULTS

Circ_0018289 expression was upregulated in tumor tissue compared with paired adjacent tissue (P < .001), and receiver operative characteristic curve disclosed its good value for separating tumor tissue from adjacent tissue with an area under curve of 0.907 (95% CI: 0.879-0.935). Additionally, tumor circ_0018289 expression was positively associated with tumor size (P = .009), lymph node metastasis (P = .005) and Federation International of Gynecology and Obstetrics stage (P = .005). The DFS (P = .005) and OS (P = .015) were both worse in patients with circ_0018289 high expression compared to patients with circ_0018289 low expression. Meanwhile, in patients with circ_0018289 high expression, DFS and OS were the longest in patients with high+ expression followed by patients with high++ expression, and the shortest in patients with high+++ expression. Moreover, circ_0018289 high expression could independently predict worse DFS in the total cervical cancer patients (P = .042).

CONCLUSION

Circ_0018289 could serve as a potential disease monitoring and prognostic biomarker in cervical cancer patients.

A New World of Biomarkers and Therapeutics for Female Reproductive System and Breast Cancers: Circular RNAs

As one of the most recently (re)discovered types of non-coding RNAs (ncRNA), circular RNAs (circRNAs) differentiate from other ncRNAs by a specific biogenesis, high stability, and distinct functions. The biogenesis of circRNAs can be categorized into three mechanisms that permit the back-splicing reaction: exon-skipping, pairing of neighboring introns, and dimerization of RNA-binding proteins. Regarding their stability, circRNAs have no free ends, specific to linear RNA molecules, prompting a longer half-life and resistance to exonuclease-mediated activity by RNase R, bypassing the common RNA turnover process. Regarding their functions, circular transcripts can be categorized into four broad roles: miRNA sponging, protein binding, regulation of transcription, and coding for proteins and peptides. Female reproductive system (including mainly ovarian, corpus, and cervix uteri cancers) and breast cancers are the primary causes of death in women worldwide, accounting for over 1,212,772 deaths in 2018. We consider that a better understanding of the molecular pathophysiology through the study of coding and non-coding RNA regulators could improve the diagnosis and therapeutics of these cancers. Developments in the field of circRNA in regard to breast or gynecological cancers are recent, with most circRNA-related discoveries having been made in the last 2 years. Therefore, in this review we summarize the newly detected roles of circRNAs in female reproductive system (cervical cancer, ovarian cancer, and endometrial cancer) and breast cancers. We argue that circRNAs can become essential elements of the diagnostic and therapeutic tools for female reproductive system cancers in the future.

The Role of microRNAs, Long Non-coding RNAs, and Circular RNAs in Cervical Cancer

Prolonged infection of uterine cervix epithelium with human papillomavirus (HPV) and constitutive expression of viral oncogenes have been recognized as the main cause of the complex molecular changes leading to transformation of cervical epithelial cells. Deregulated expression of microRNAs (miRNA), long non-coding RNAs (lncRNA), and circular RNAs (circRNA) is involved in the initiation and promotion processes of cervical cancer development. Expression profiling of small RNAs in cervical neoplasia revealed up-regulated “oncogenic” miRNAs, such as miR-10a, miR-21, miR-19, and miR-146a, and down regulated “tumor suppressive” miRNAs, including miR-29a, miR-372, miR-214, and miR-218, associated with cell growth, malignant transformation, cell migration, and invasion. Also several lncRNAs, comprising among others HOTAIR, MALAT1, GAS5, and MEG3, have shown to be associated with various pathogenic processes such as tumor progression, invasion as well as therapeutic resistance and emerged as new diagnostic and prognostic biomarkers in cervical cancer. Moreover, human genes encoded circular RNAs, such as has_circ-0018289, have shown to sponge specific miRNAs and to concur to the deregulation of target genes. Viral encoded circE7 has also demonstrated to overexpress E7 oncoprotein thus contributing to cell transformation. In this review, we summarize current literature on the complex interplay between miRNAs, lncRNAs, and circRNAs and their role in cervical neoplasia.

circ-MYBL2 Serves As A Sponge For miR-361-3p Promoting Cervical Cancer Cells Proliferation And Invasion

Background

Circular RNAs (circRNAs) have been considered as a key regulator in tumor carcinogenesis. However, the roles and underlying mechanisms of circRNAs in cervical cancer (CC) remain largely unknown. In this study, we explored the effects of circ-MYBL2 (hsa_circ_0060467) on CC progression.

Methods

Levels of circ-MYBL2 and miR-361-3p were examined by qRT-PCR. CCK-8 assay, colony formation assay and transwell invasion assay were used to determine the roles of circ-MYBL2 in CC. Dual-luciferase reporter and RNA pull down assays were employed to verify the relationship between circ-MYBL2 and miR-361-3p.

Results

We showed that the expression of circ-MYBL2 was significantly upregulated and positively associated with advanced FIGO stage, larger tumor size, lymph node metastasis, and poor prognosis in CC patients. Function assays revealed that circ-MYBL2 inhibition suppressed CC cells’ proliferation, invasion and epithelial–mesenchymal transition (EMT) processes. In mechanism, miR-361-3p was identified as a direct target of circ-MYBL2, rescue assays showed that miR-361-3p suppression reversed the effects of si-circ-MYBL2 on CC cells’ progression.

Conclusion

Our findings suggested that circ-MYBL2 promoted CC progression by regulating miR-361-3p expression, which provided a novel therapeutic target for the treatment of CC patients.

Star Circular RNAs In Human Cancer: Progress And Perspectives

Circular RNAs (circRNAs) are a recently discovered subclass of non-coding RNAs (ncRNAs) characterized by a covalently closed loop structure created by reverse splicing. Because they do not have a 5' cap structure and a 3' poly A tail, circRNAs have higher stability, abundance and evolutionary conservation than linear RNA between species. These features produce various potential biological functions of circRNAs, such as miRNA sponges, RNA-binding proteins that form RNA protein complexes. In recent years, more and more studies have shown that circRNAs play a vital role in the occurrence and development of human diseases. At the same time, their enormous potential as a biomarker and therapeutic target is also evolving. The purpose of this review is to summarize existing cancer-associated circRNAs and to try to find circRNAs that are abnormally expressed in many cancers. Therefore, we reviewed previous circRNAs studies related to cancer and selected them by statistics. The eight circRNAs that have the highest frequency in different cancers or involve key pathways are called star circRNAs. Here, we review the classification, features, and functions of emerging star circRNAs, with particular attention to the role of circRNAs in various cancers.