Serum Circular FoxO3a Serves as a Novel Prognostic Biomarker in Squamous Cervical Cancer

Circular RNAs and cervical cancer: friends or foes? A landscape on circRNA-mediated regulation of key signaling pathways involved in the onset and progression of HPV-related cervical neoplasms

Cervical cancer (CC) is a common gynecologic malignancy, accounting for a significant proportion of women death worldwide. Human papillomavirus (HPV) infection is one of the major etiological causes leading to CC onset; however, genetic, and epigenetic factors are also responsible for disease expansion. Circular RNAs (circRNAs), which are known as a particular subset of non-coding RNA (ncRNA) superfamily, with covalently closed loop structures, have been reported to be involved in the progression of diverse diseases, especially neoplasms. In this framework, abnormally expressed circRNAs are in strong correlation with CC pathogenesis through regulating substantial signaling pathways. Also, these RNA molecules can be considered as promising biomarkers and therapeutic targets for CC diagnosis/prognosis and treatment, respectively. Herein, we first review key molecular mechanisms, including Wnt/β-catenin, MAPK, and PI3K/Akt/mTOR signaling pathways, as well as angiogenesis and metastasis, by which circRNAs interfere with CC development. Then, diagnostic, prognostic, and therapeutic potentials of these ncRNA molecules will be highlighted in depth.

Foxo3a-Mediated DNMT3B Impedes Cervical Cancer Cell Proliferation and Migration Capacities through Suppressing PTEN Promoter Methylation

OBJECTIVE

Cervical cancer is linked with the constitutive activation of growth factors and gene mutations-induced pro-survival signaling pathways. Herein, we purposed to explore the possible molecular mechanism of Foxo3a-mediated DNMT3B in the proliferation and migration of cervical cancer cells via mediating the PTEN promoter methylation.

METHODS

Foxo3a expression in cervical cancer was tested by qRT-PCR and western blot experiments. The cervical cancer cell biological functions with overexpression of Foxo3a were evaluated by CCK-8 assay, Transwell experiment, and flow cytometry, respectively. MS-PCR was utilized for testing the PTEN methylation levels, and ChIP experiment was implemented for evaluating the enrichment of DNMT3B in the PTEN promoter region and the binding of Foxo3a and DNMT3B. The PTEN methylation and interference with Foxo3a expression were performed in cervical cancer cells, and then their impacts on cervical cancer cell biological functions were observed.

RESULTS

FOXO3a was expressed at a low level in cervical cancer, and its overexpression contributed to a reduction in cell proliferative, migratory and invasive capabilities, and an elevation in apoptosis rate. Foxo3a blocked its methylation with the PTEN promoter by repressing DNMT3B activity. Upon treatment with methyltransferase inhibitor (5-aza-dc), the malignant phenotypes of cervical cancer cells were diminished. 5-aza-dc neutralized the impacts of silencing Foxo3a on malignant phenotypes.

CONCLUSION

This research underlines that Foxo3a blocks its methylation with the PTEN promoter by inhibiting DNMT3B activity, which subsequently impedes cervical cancer cell progression.

Sodium selenite inhibits cervical cancer growth via ROS mediated AMPK/FOXO3a /GADD45a axis

Selenium is a trace element that has been shown to inhibit the growth of various cancer cell types. However, its role in cervical cancer and its underlying mechanisms remains largely unknown. Herein, we explored the anti-cervical cancer effect of selenium and its potential mechanisms through xenograft and in vitro experiments. HeLa cell xenografts in female nude mice showed tumor growth retardation, with no obvious liver and kidney toxicity, after being intraperitoneally injected with 3 mg/kg sodium selenite (SS) for 14 days. Compared to the control group, selenium levels in the tumor tissue increased significantly after SS treatment. In vitro experiments, SS inhibited the viability of HeLa and SiHa cells, blocked the cell cycle at the S phase, and enhanced apoptosis. RNA-sequencing, Kyoto encyclopedia of genes and genomes pathway analysis showed that forkhead box protein O (FOXO) was a key regulatory signaling pathway for SS to exhibit anticancer effects. Gene Ontology analysis filtered multiple terms associated with apoptosis, anti-proliferation, and cell cycle arrest. Further research revealed that SS increased intracellular reactive oxygen species (ROS) and impaired mitochondrial function, which activated adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) via phosphorylation at Thr172, resulting in activation of FOXO3a and its downstream growth arrest and DNA damage-inducible alpha (GADD45a). In summary, SS exhibited anti-cervical cancer effects, and their mechanisms may be that SS is involved in inducing cell cycle arrest and potentiating cell apoptosis caused by ROS-dependent activation of the AMPK/FOXO3a/GADD45a axis.

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.

Plasma circRNA microarray profiling identifies novel circRNA biomarkers for the diagnosis of ovarian cancer

Background

Circular RNA (circRNA), a class of RNA with a covalent closed circular structure that widely existed in serum and plasma, has been considered an ideal liquid biopsy marker in many diseases. In this study, we employed microarray and qRT-PCR to evaluate the potential circulating circRNAs with diagnostic efficacy in ovarian cancer.

Methods

We used microarray to explore the circRNA expression profile in ovarian cancer patients’ plasma and quantitative real-time (qRT)-PCR approach to assessing the candidate circRNA’s expression. Then the receiver operating characteristic (ROC) curve was employed to analyze the diagnostic values of candidate circRNAs. The diagnostic model circCOMBO was a combination of hsa_circ_0003972 and hsa_circ_0007288 built by binary logistic regression. Then bioinformatic tools were used to predict their potential mechanisms.

Results

Hsa_circ_0003972 and hsa_circ_0007288 were downregulated in ovarian cancer patients’ plasma, tissues, and cell lines, comparing with the controls. Hsa_circ_0003972 and hsa_circ_0007288 exhibited diagnostic values with the Area Under Curve (AUC) of 0.724 and 0.790, respectively. circCOMBO showed a better diagnostic utility (AUC: 0.781), while the combination of circCOMBO and carbohydrate antigen 125 (CA125) showed the highest diagnostic value (AUC: 0.923). Furthermore, the higher expression level of hsa_circ_0007288 in both plasma and ovarian cancer tissues was associated with lower lymph node metastasis potential in ovarian cancer.

Conclusions

Our results revealed that hsa_circ_0003972 and hsa_circ_0007288 may serve as novel circulating biomarkers for ovarian cancer diagnosis.

Supplementary information

The online version contains supplementary material available at 10.1186/s13048-022-00988-0.

Circular RNAs as emerging players in cervical cancer tumorigenesis; A review to roles and biomarker potentials

Cervical cancer is the most lethal gynecological cancer among women worldwide. Most of the patients are diagnosed at the advanced stages due to late diagnosis and lack of accessible and valuable approaches for early detection of the disease. Circular RNAs (circRNAs) are a distinguishable class of non-coding RNAs with characteristic loop structures. Although their function has not been completely elucidated; however, recent evidence has suggested regulatory functions for circRNAs on gene expression controlling various biological functions like cell growth and apoptosis, development, embryogenesis, and pathogenesis of human diseases particularly cancers. Studies show the role of dysregulated circRNAs in biological processes including cell proliferation, migration, invasion, apoptosis, angiogenesis, and chemoresistance contributing to affect tumorigenesis in ovarian cancer cells, animal, and clinical studies. These effects can be defined as consistent with several tumorigenesis characteristics, which are defined as "hallmarks of cancer". Additionally, dysregulated circRNAs exhibit prognostic, and diagnostic potentials both in the prediction of prognosis in ovarian cancer patients, and also their discrimination from healthy individuals. Furthermore, targeting circRNAs has shown positive results in the suppression of malignant features of cancer cells, and also in overcoming chemoresistance. In this review, I have gathered the majority of studies evaluating the role of circRNAs in the development, and progression of cervical cancer, and also have discussed prognostic, diagnostic, and therapeutic potentials of circRNAs for clinical applications in cervical cancer patients.

Tumor-Derived circRNAs as Circulating Biomarkers for Breast Cancer

Early diagnosis is the key to improving the prognosis of breast cancer (BC) patients; however, there are currently no circulating biomarkers that demonstrate good sensitivity and specificity. This study applied circular RNA (circRNA) microarray analysis, screening, and verification in BC plasma samples to identify three tumor-derived differentially expressed circRNAs: hsa_circ_0000091, hsa_circ_0067772, and hsa_circ_0000512. We constructed a diagnostic model using logistic regression analysis in the training set and established an optimal diagnostic model based on the three circRNAs, which showed sensitivity, specificity, and area under the curve (AUC) values of .971, .902, and .974, respectively. We then verified the diagnostic model in the test set which showed satisfactory stability for BC diagnosis. Additionally, the expression of hsa_circ_0000091 in plasma correlated with axillary lymph node (ALN) metastasis, TNM stage, and prognosis of BC patients. Furthermore, hsa_circ_0000091 combined with ultrasound showed predictive ability for ALN metastasis, with an AUC of .808. These findings suggested that the three identified circRNAs can be used as circulating biomarkers for BC diagnosis, with hsa_circ_0000091 potentially representing a prognostic biomarker for BC and novel approach for predicting ALN metastasis.

The potential of using blood circular RNA as liquid biopsy biomarker for human diseases

Circular RNA (circRNA) is a novel class of single-stranded RNAs with a closed loop structure. The majority of circRNAs are formed by a back-splicing process in pre-mRNA splicing. Their expression is dynamically regulated and shows spatiotemporal patterns among cell types, tissues and developmental stages. CircRNAs have important biological functions in many physiological processes, and their aberrant expression is implicated in many human diseases. Due to their high stability, circRNAs are becoming promising biomarkers in many human diseases, such as cardiovascular diseases, autoimmune diseases and human cancers. In this review, we focus on the translational potential of using human blood circRNAs as liquid biopsy biomarkers for human diseases. We highlight their abundant expression, essential biological functions and significant correlations to human diseases in various components of peripheral blood, including whole blood, blood cells and extracellular vesicles. In addition, we summarize the current knowledge of blood circRNA biomarkers for disease diagnosis or prognosis.

Hsa_circ_0069094 knockdown inhibits cell proliferation, migration, invasion and glycolysis, while induces cell apoptosis by miR-661/HMGA1 axis in breast cancer

Circular RNAs (circRNAs) are revealed to regulate breast cancer progression. This study aimed to investigate hsa_circ_0069094-mediated effects on breast cancer cell malignancy. Quantitative real time PCR was employed to evaluate the expressions of hsa_circ_0069094, miR-661 and high mobility group A1 (HMGA1). Western blot was performed to determine the protein expression of HMGA1 and proliferating cell nuclear antigen. Breast cancer malignant progressions were explained by cell counting kit-8 proliferation, cell colony formation, flow cytometry analysis, wound-healing and transwell assays. Cell glycolysis was assessed by detecting glucose take, lactate production and hexokinase 2 (HK2) protein level. The target relationship between miR-661 and hsa_circ_0069094 or HMGA1 was predicted by circular RNA interactome and targetscan online databases, and identified by dual-luciferase reporter and RNA immunoprecipitation assay. The effects of hsa_circ_0069094 knockdown on breast cancer growth in vivo were elucidated by in vivo tumor formation assay. Hsa_circ_0069094 and HMGA1 expression were significantly upregulated, while miR-661 expression level was downregulated in breast cancer tissues and cells relative to adjacent normal breast tissues or MCF-10A cells. Functionally, hsa_circ_0069094 knockdown inhibited cell glycolysis, proliferation, migration and invasion, whereas induced cell apoptosis in breast cancer, which was decreased by miR-661 inhibitor. Mechanistically, hsa_circ_0069094 regulated HMGA1 by sponging miR-661. Furthermore, hsa_circ_0069094 knockdown repressed tumor formation in vivo. Collectively, hsa_circ_0069094 knockdown repressed breast cancer cell carcinogenesis and cell glycolysis by regulating HMGA1 through sponging miR-661, which provided a new insight for studying the mechanism of hsa_circ_0069094 in modulating breast cancer development.

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.

Diagnostic and Prognostic Value of Circulating CircRNAs in Cancer

Cancer has been regarded as one of the leading causes of mortality worldwide. Diagnostic and prognostic biomarkers with high sensitivity and specificity for cancer play a crucial role in preventing or treating cancer. Circular RNAs (circRNAs), which hold great potential for the management of cancer patients due to their abundance, stable property, and high specificity in serum, plasma, and other body fluids, can be used as non-invasive and blood-based biomarkers in cancer diagnosis and prognosis. There are four types of circRNAs including exonic circRNAs (ecircRNA), intronic circRNAs, exon-intron circRNAs (EIciRNA), and intergenic circRNAs. CircRNAs can act as miRNA sponges, affect protein translation, interplay with RNA binding proteins, regulate protein recruitment, and modulate protein scaffolding and assembly. Therefore, the multifunctionalities of circRNAs make them ideal for detecting and predicting cancer. Indeed, circRNAs manifest high sensitivity and specificity in more than ten types of cancer. This review aims to consolidate the types and functions of circRNAs, as well as discuss the diagnostic and prognostic value of circulating circRNAs in cancer.

A novel prognostic nomogram utilizing the 2018 FIGO staging system for cervical cancer: A large multicenter study

OBJECTIVE

To evaluate the prognostic performance of the revised 2018 FIGO staging system for cervical cancer.

METHODS

This retrospective multicenter study enrolled cervical cancer patients with 2009 FIGO Stage IA1-IIA2 who underwent surgeries between January 2006 and December 2017 in four tertiary hospitals. Patients were restaged according to the 2018 FIGO staging system by reviewing their medical data.

RESULTS

Of 3238 cervical cancer patients included, 1841 (56.9%) patients were restaged: 641 (34.9%) due to tumor size, 544 (29.5%) due to lymph node metastasis, 614 (33.4%) due to the inconsistency between pre- and postoperative assessments, and 42 due to the cancellation of invasion width in Stage IA. After restaging, a clear tendency of decreased recurrence-free survival (RFS) and overall survival (OS) with increasing stage was observed. Multivariate Cox analysis showed that 2018 FIGO stage, parametrial involvement, and histology were independent prognostic factors for both OS and RFS (P < 0.05). Based on these factors, we established predictive nomograms with c-indexes of 0.735 and 0.721, showing good predictive ability for cervical cancer.

CONCLUSION

The revised 2018 FIGO staging system can better reflect the survival of cervical cancer patients. Based on it, we established a nomogram that can predict the prognosis of cervical cancer patients more precisely.

Circular RNAs in body fluids as cancer biomarkers: the new frontier of liquid biopsies

Cancer is a leading cause of death worldwide, particularly because of its high mortality rate in patients who are diagnosed at late stages. Conventional biomarkers originating from blood are widely used for cancer diagnosis, but their low sensitivity and specificity limit their widespread application in cancer screening among the general population. Currently, emerging studies are exploiting novel, highly-accurate biomarkers in human body fluids that are obtainable through minimally invasive techniques, which is defined as liquid biopsy. Circular RNAs (circRNAs) are a newly discovered class of noncoding RNAs generated mainly by pre-mRNA splicing. Following the rapid development of high-throughput transcriptome analysis techniques, numerous circRNAs have been recognized to exist stably and at high levels in body fluids, including plasma, serum, exosomes, and urine. CircRNA expression patterns exhibit distinctly differences between patients with cancer and healthy controls, suggesting that circRNAs in body fluids potentially represent novel biomarkers for monitoring cancer development and progression. In this study, we summarized the expression of circRNAs in body fluids in a pan-cancer dataset and characterized their clinical applications in liquid biopsy for cancer diagnosis and prognosis. In addition, a user-friendly web interface was developed to visualize each circRNA in fluids (https://mulongdu.shinyapps.io/circrnas_in_fluids/).

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.

Comprehensive Assessment of Plasma Circ_0004771 as a Novel Diagnostic and Dynamic Monitoring Biomarker in Gastric Cancer

Purpose

Due to the lack of specific and sensitive detection indicators, most patients with GC are already in the advanced stage at the time of diagnosis. Therefore, it is urgent to search for effective diagnostic biomarkers that can be applied in clinic.

Materials and Methods

We screened out circ_0004771 through circRNA sequencing. Exonuclease digestion assay, agarose gel electrophoresis (AGE) and Sanger sequencing verified the potential of circ_0004771 being a biomarker. Additionally, we established quantitative real-time fluorescent polymerase chain reaction (qRT-PCR) to detect the expression level of circ_0004771 and evaluated the methodology. What's more, we collected plasma samples from 120 GC patients, 40 superficial gastritis patients, 20 postoperative GC patients, 20 postoperative recurrence patients and 120 healthy donors. We constructed the receiver operating characteristic curve (ROC) to appraise its diagnostic efficacy.

Results

The expression level of circ_0004771 is up-regulated in GC tissues, which is consistent with circRNA sequencing result (P=0.0001). Circ_0004771 can serve as a promising biomarker because of its stable structure and longer half-life. Plasma circ_0004771 expression is markedly richer in GC patients than that in normal people (P<0.0001), and the area under the ROC (AUC) is 0.831 (95% CI: 0.779–0.883). The diagnostic efficacy of circ_0004771 is higher than that of CEA (AUC=0.747, 95% CI: 0.686–0.808) and CA199 (AUC=0.508, 95% CI: 0.433–0.583). Higher diagnostic efficacy can be achieved by combination diagnosis for distinguishing GC patients from normal people (AUC=0.864). Besides, the expression level of circ_0004771 can distinguish GC patients from gastritis patients (AUC=0.845, 95% CI: 0.772–0.917). The plasma circ_0004771 expression in GC patients decreased to normal after surgery (P<0.0001). In addition, plasma circ_0004771 expression increased again in patients with postoperative recurrence.

Conclusion

Plasma circ_0004771 is differentially expressed in GC patients, postoperative GC patients and patients with recurrence, suggesting that plasma circ_0004771 can be used as a novel diagnostic and dynamic monitoring biomarker in GC.