Circular RNA: A potential diagnostic, prognostic, and therapeutic biomarker for human triple-negative breast cancer

Circ_0081723 enhances cervical cancer progression and modulates CREBRF via sponging miR-545-3p

Circular RNAs (circRNAs) have been confirmed to be an important modulator and therapeutic target of cervical cancer (CC). The aim of this study is to explore the role and mechanism of circ_0081723 in CC progression. Circ_0081723, microRNA-545-3p (miR-545-3p), and CREB3 regulatory factor (CREBRF) levels were detected using quantitative real-time PCR (qRT-PCR) assay. CREBRF, ki-67, Bcl-2 related X protein (Bax), and E-cadherin expression levels were determined using western blot (WB) and immunohistochemistry (IHC) assays. Cell proliferation was assessed using Cell Counting Kit-8 (CCK-8), cell colony formation, and 5-ethynyl-2'-deoxyuridine (EdU) assays. Flow cytometry was used to measure cell apoptosis.  Cell migration and invasion were examined using Transwell assay. Interaction between miR-545-3p and circ_0081723 or CREBRF was verified using dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assays. The biological role of circ_0081723 on CC growth was examined using the xenograft tumor model in vivo. Circ_0081723 and CREBRF were increased, and miR-545-3p was decreased in CC tissues and cells. Circ_0081723 silencing suppressed CC cell growth and motility whereas boosted CC cell apoptosis. Besides, circ_0081723 acted as a molecular sponge for miR-545-3p, and circ_0081723 knockdown-induced effects were largely reversed by miR-545-3p downregulation in CC cells. Moreover, miR-545-3p repressed CC progression by targeting CREBRF.  Circ_0081723 absence blocked xenograft tumor growth in vivo. Circ_0081723 stimulated CC cell malignant behaviors by regulating the miR-545-3p/CREBRF pathway, providing a possible circRNA-targeted therapy for CC.

Inhibition of breast cancer cell growth and migration through siRNA-mediated modulation of circ_0009910/miR-145-5p/MUC1 axis

Circular RNAs (circRNAs) characterize a novel kind of regulatory RNAs distinguished by great evolutionary conservation and constancy. Although their exact role in malignancies is not fully understood, they mainly work through specific axes. Circular RNA/miRNA/mRNA axes affect the pathogenesis of human cancers including breast cancer. We assessed the expression and function of circ_0009910/miR-145-5p/MUC1 axis in Breast Cancer tissues and MCF-7 cells. Expression levels of circ_0009910 and MUC1 were notably increased in breast cancer tissues compared with control tissues, parallel with the down-regulation of miR-145-5p. Clinicopathological analysis indicated that up-regulation of circ_0009910 in breast tumors is related to invasion of the tumor to lymph node (P value = 0.011). Also, the downregulation of miR-145-5p was significantly correlated with tumor invasion to lymph nodes (P value = 0.04) and HER2-negative tumors (P value = 0.037). Finally, overexpression of MUC1 was correlated with age under 45 years (P value = 0.002). More importantly, circ_0009910-siRNA decreased the proliferation and migration ability of breast cancer cells, enhanced expression of miR-145-5p, and decreased levels of MUC1. Taken together, the circ_0009910/miR-145-5p/MUC1 axis has been demonstrated to affect the pathogenesis of breast cancer and might provide a target for breast cancer treatment.

CircSEPT9 promotes breast cancer progression by regulating PTBP3 expression via sponging miR-625-5p

BACKGROUND

Breast cancer (BC) is a common malignancy which threatens the health of women. Circular RNAs (circRNAs) are critical factors in multiple cancers, including BC. The aim of this experiment was to investigate the molecular mechanisms of circRNA Septin 9 (circSEPT9) in the progression of BC.

METHODS

CircSEPT9, microRNA-625-5p (miR-625-5p) and polypyrimidine tract-binding protein 3 (PTBP3) levels were determined by quantitative real-time polymerase chain reaction (qRT-PCR). Western blot was performed to detect the protein levels of PTBP3, E-cadherin and vimentin. Cell counting kit-8 assay (CCK8) and thymidine analog 5-ethynyl-2'-deoxyuridine (EDU) was utilized for proliferation examination. Flow cytometry was conducted to measure apoptosis. Transwell assay and wound healing assay to investigate the migration of BC cells. Glucose uptake and lactate production were determined by specific kits. Additionally, dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were utilized to verify the interaction. A murine xenograft model was established to investigate the function of circSEPT9 in BC in vivo.

RESULTS

Overexpression of circSEPT9 was found in BC tissues and cells. Silencing circSEPT9 impeded BC cell proliferation, migration, epithelial-mesenchymal transition (EMT) and glycolytic metabolism but facilitated cell apoptosis in vitro. Meanwhile, circSEPT9 knockdown constrained tumor growth in vivo. MiR-625-5p was targeted by circSEPT9. The influence of silencing circSEPT9 on BC cell function was regained by miR-625-5p inhibitor. Furthermore, miR-625-5p regulated BC cell malignant phenotypes via downregulating PTBP3.

CONCLUSION

circSEPT9 contributed to the malignant progression of BC by up-regulating PTBP3 via sponging miR-625-5p.

Genomic Alterations Affecting Competitive Endogenous RNAs (ceRNAs) and Regulatory Networks (ceRNETs) with Clinical Implications in Triple-Negative Breast Cancer (TNBC)

The concept of competitive endogenous RNA regulation has brought on a change in the way we think about transcriptional regulation by miRNA-mRNA interactions. Rather than the relatively simple idea of miRNAs negatively regulating mRNA transcripts, mRNAs and other non-coding RNAs can regulate miRNAs and, therefore, broad networks of gene products through competitive interactions. While this concept is not new, its significant roles in and implications on cancer have just recently come to light. The field is now ripe for the extrapolation of technologies with a substantial clinical impact on cancer. With the majority of the genome consisting of non-coding regions encoding regulatory RNAs, genomic alterations in cancer have considerable effects on these networks that have been previously unappreciated. Triple-negative breast cancer (TNBC) is characterized by high mutational burden, genomic instability and heterogeneity, making this aggressive breast cancer subtype particularly relevant to these changes. In the past few years, much has been learned about the roles of competitive endogenous RNA network regulation in tumorigenesis, disease progression and drug response in triple-negative breast cancer. In this review, we present a comprehensive view of the new knowledge and future perspectives on competitive endogenous RNA networks affected by genomic alterations in triple-negative breast cancer. An overview of the competitive endogenous RNA (ceRNA) hypothesis and its bearing on cellular function and disease is provided, followed by a thorough review of the literature surrounding key competitive endogenous RNAs in triple-negative breast cancer, the genomic alterations affecting them, key disease-relevant molecular and functional pathways regulated by them and the clinical implications and significance of their dysregulation. New knowledge of the roles of these regulatory mechanisms and the current acceleration of research in the field promises to generate insights into the diagnosis, classification and treatment of triple-negative breast cancer through the elucidation of new molecular mechanisms, therapeutic targets and biomarkers.

circ_0058063 promotes breast cancer progression by upregulating DLGAP5 via sponging miR-557

OBJECTIVE

Accumulating evidence indicates that circular RNAs (circRNAs) contribute to breast cancer (BC) development and progression. However, the role of circ_0058063 in BC and its underlying molecular processes remain unclear.

METHODS

The expression of circ_0058063, miR-557, and DLGAP5 in BC tissues and cells was determined using real time quantitative PCR or western blotting. The functions of circ_0058063 in BC cells were detected using CCK-8, Transwell, caspase-3 activity, and xenograft tumor assays. The specific binding of circ_0058063/miR-557 and DLGAP5/miR-557 was verified using RNA immunoprecipitation (RIP) and dual-luciferase reporter assays.

RESULTS

circ_0058063 expression was upregulated in BC tissues and cells. circ_0058063 knockdown inhibited proliferation and migration but promoted apoptosis in MCF-7 and MDA-MB-231 cells in vitro. In vivo studies further validated that the knockdown of circ_0058063 repressed tumor growth. Mechanistically, circ_0058063 directly sponged miR-557 and negatively regulated its expression. Additionally, miR-557 inhibition reversed the tumor-suppressive effects of the circ_0058063 knockdown on the survival of MDA-MB-231 and MCF-7 cells. Moreover, miR-557 directly targeted DLGAP5. DLGAP5 knockdown suppressed MCF-7 and MDA-MB-231 cell growth, and these effects were reversed by miR-557 downregulation.

CONCLUSION

Our findings verify that circ_0058063 acts as a sponge for miR-557 to upregulate DLGAP5 expression. These findings suggest that the circ_0058063/miR-557/DLGAP5 axis is an important regulator of oncogenic function and may be a promising therapeutic target for BC.

CircTMEM87A promotes the tumorigenesis of gastric cancer by regulating the miR-1276/SLC7A11 axis

BACKGROUND

Gastric cancer (GC) is a common malignancy with high incidence and mortality, and its pathogenesis involves the regulation of circular RNAs (circRNAs). However, the molecular mechanism of circTMEM87A in GC malignant progression is uncertain.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to detect the expressions of circTMEM87A, miR-1276, and solute carrier family 7 membrane 11 (SLC7A11). Western blot was applied to detect protein expression levels of EMT-related proteins (vimentin and E-cadherin) and SLC7A11. Cell counting kit-8 assay (CCK8) and thymidine analog 5-ethynyl-2'-deoxyuridine (EdU) were performed to assess cell proliferation. Apoptosis was investigated using flow cytometry. Transwell assay and wound healing assay were carried out to examine the migration of MKN-7 and AGS cells. The Cellular ROS Assay Kit, Iron Assay Kit, and GSH/GSSG Ratio Detection Assay Kit were utilized to monitor lipid ROS level, iron level, and GSH/GSSG ratio, respectively. The interaction between miR-1276 and circTMEM87A or SLC7A11 was investigated using dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. A xenograft mouse model was constructed to explore the function of circTMEM87A in tumor formation in vivo.

RESULTS

CircTMEM87A and SLC7A11 were upregulated, while miR-1276 was downregulated in GC tissues and cells. Knockdown of circTMEM87A suppressed the proliferation and migration and promoted apoptosis and ferroptosis of GC cells. CircTMEM87A served as a sponge for miR-1276, and miR-1276 inhibitor relieved the circTMEM87A knockdown-induced effects on GC cell phenotypes. Similarly, SLC7A11, a downstream gene of miR-1276, rescued miR-1276 overexpression-induced effects on GC cell function. Furthermore, circTMEM87A knockdown inhibited GC cell tumor phenotypes in vivo.

CONCLUSION

CircTMEM87A promoted the proliferation and migration and inhibited apoptosis and ferroptosis of GC cells by increasing SLC7A11 expression through binding to miR-1276.

WASF3 overexpression affects the expression of circular RNA hsa-circ-0100153, which promotes breast cancer progression by sponging hsa-miR-31, hsa-miR-767-3p, and hsa-miR-935

Background

The WASF3 gene has been linked to promoting metastasis in breast cancer (BC) cells, and low expression reduces invasion potential. Circular RNAs (circRNAs) function as microRNA (miRNA) modulators and are involved in cancer progression, but the relationship between these factors remains unclear.

Methods

This study used bioinformatics methods and a computational approach to investigate the role of circRNAs and miRNAs in the context of WASF3 overexpression. Differentially expressed mRNAs, circRNAs, and miRNAs were identified using Gene Expression Omnibus (GEO) datasets. A competing endogenous RNA (ceRNA) network was constructed based on circRNA-miRNA pairs and miRNA-mRNA pairs. Functional and pathway enrichment analyses were predicted using a circRNA-miRNA-mRNA network.

Results

RNA expression patterns were significantly different between normal and tumor samples. A total of 190 circRNAs, 76 miRNAs, and 678 mRNAs were differentially expressed. The analysis of the circRNA-miRNA-mRNA regulatory network revealed interactions between hsa-circ-0100153, hsa-miR-31, hsa-miR-767-3p, and hsa-miR-935 with WASF3 in cancer. These interactions primarily function in DNA replication and the cell cycle.

Conclusions

This study reveals a mechanism by which WASF3 overexpression affects the expression of circRNAs hsa-circ-0100153, promoting BC progression by sponging hsa-miR-31/hsa-miR-767-3p /hsa-miR-935. This mechanism may increase the invasive potential of cancers, in addition to other reported molecular mechanisms involving the WASF3 gene.

Circular RNAs in the chemoresistance of triple-negative breast cancer: A systematic review

This study aims to assess studies on circular RNAs (circRNAs) in the chemoresistance of triple-negative breast cancer (TNBC) and provide relevant references for the development of new TNBC chemotherapy sensitivity biomarkers and therapeutic targets. The PubMed, Embase, Web of Knowledge, Cochrane Library, and four Chinese databases were searched up to January 27, 2023, and studies related to TNBC chemoresistance were included. The basic characteristics of the studies and the mechanisms of circRNAs in regulating TNBC chemoresistance were analyzed. A total of 28 studies published between 2018 and 2023 were included, and the chemotherapeutics included adriamycin, paclitaxel, docetaxel, 5-fluorouracil, lapatinib, and so forth. A total of 30 circRNAs were identified, 86.67% (n = 26) of these circRNAs were reported to act as microRNA (miRNA) sponges to regulate chemotherapy sensitivity, while only two circRNAs (circRNA-MTO1 and circRNA-CREIT) interacted with proteins. A total of 14, 12, and 2 circRNAs were reported to be associated with chemoresistance to adriamycin, taxanes, and 5-fluorouracil, respectively. Six circRNAs were found to act as miRNA sponges that promote chemotherapy resistance by regulating the PI3K/Akt signalling pathway. CircRNAs participate in the regulation of TNBC chemoresistance and can be used as biomarkers and therapeutic targets for improving chemotherapy sensitivity. However, further studies are needed to confirm the role of circRNAs in TNBC chemoresistance.

circGFRA1: A circular RNA with important roles in human carcinogenesis

Circular RNAs (circRNAs) are a type of covalently closed RNA molecules, which are mainly formed by back splicing of a precursor mRNA upstream exon into a downstream exon. Abnormally expressed circRNAs can modulate gene transcription by indirectly interacting with microRNAs (miRNAs). According to the current studies, circGFRA1 has been suggested to be upregulated in various cancers. circGFRA1 (hsa_circ_005239) is a type of cancer-related circRNA, which is predicted to be originated from the GFRA1 on chromosome 10. circGFRA1 can act as a sponge for several miRNAs, including miR-34a, miR-1228, miR-361-5p, miR-149, miR-498, miR-188-3p, miR-3064-5p, miR-449a. Additionally, it can regulate signaling pathways such as TGF-β and PI3K/ AKT. circGFRA1 upregulation has been correlated with patients' poor overall survival in diverse cancers. In the present review, we have summarized the oncogenic effect of circGFRA1 in various cancers according to the adopted criteria from in vitro, in vivo, and clinical research. Moreover, functional enrichment analysis was performed on the circGFRA1 host gene and its protein interaction network to detect gene ontology and related pathways.

CircNCOR1 regulates breast cancer radiotherapy efficacy by regulating CDK2 via hsa-miR-638 binding

BACKGROUND

Despite aggressive local and regional therapy, triple-negative breast cancer (TNBC) is characterized by an increased risk of locoregional recurrence. RNA-sequencing data has identified a large number of circRNAs in primary breast cancers, but the role of specific circRNAs in regulating the radiosensitivity of TNBC is not fully understood. This research aimed to investigate the function of circNCOR1 in the radiosensitivity of TNBC.

METHODS

CircRNA high-throughput sequencing was conducted on two breast cancer MDA-MB-231 and BT549 cell lines after 6 Gy radiation. The relationship between circNCOR1, hsa-miR-638, and CDK2 was determined by RNA immunoprecipitation (RIP), FISH and luciferase assays. The proliferation and apoptosis of breast cancer cells were measured by CCK8, flow cytometry, colony formation assays, and western blot.

RESULTS

Differential expression of circRNAs was closely related to the proliferation of breast cancer cells after irradiation. Overexpression of circNCOR1 facilitated the proliferation of MDA-MB-231 and BT549 cells and impaired the radiosensitivity of breast cancer cells. Additionally, circNCOR1 acted as a sponge for hsa-miR-638 to regulate the downstream target protein CDK2. Overexpression of hsa-miR-638 promoted apoptosis of breast cancer cells, while overexpression of CDK2 alleviated apoptosis and increased proliferation and clonogenicity. In vivo, overexpression of circNCOR1 partially reversed radiation-induced loosening of tumor structures and enhanced tumor cell proliferation.

CONCLUSION

Our results demonstrated that circNCOR1 bounds to hsa-miR-638 and targets CDK2, thereby regulating the radiosensitivity of TNBC.

CircEGFR reduces the sensitivity of pirarubicin and regulates the malignant progression of triple-negative breast cancer via the miR-1299/EGFR axis

Circular RNAs (circRNAs) have been found to be involved in cancer progression and chemotherapy sensitivity. However, the biological function of circRNAs in triple-negative breast cancer (TNBC) and its effect on the sensitivity to pirarubicin (THP) chemotherapy are still unclear. CircEGFR (hsa_circ_0080220) was screened and verified by bioinformatics analysis, proving it was highly expressed in TNBC cell lines, patient tissues, and plasma exosomes, and was associated with poor prognosis of patients. The expression level of circEGFR in patient tissue has potential diagnostic value to distinguish TNBC tissue from normal breast tissue. In vitro studies confirmed that overexpression of circEGFR promoted the proliferation, migration, invasion, and EMT of TNBC cells and decreased the sensitivity of THP treatment while silencing circEGFR showed the opposite effect. The circEGFR/miR-1299/EGFR pathway was cascaded and verified. CircEGFR regulated malignant progression of TNBC by regulating EGFR via sponging miR-1299. THP can inhibit the malignant phenotype of MDA-MB-231 cells by downregulating the expression of circEGFR. In vivo studies confirmed that overexpression of circEGFR can promote tumor growth and EMT and reduce tumor sensitivity to THP treatment. Silencing circEGFR inhibited the malignant progression of the tumor. These results revealed circEGFR is a promising biomarker for TNBC diagnosis, therapeutic and prognosis.

Inverse Impact of Cancer Drugs on Circular and Linear RNAs in Breast Cancer Cell Lines

Altered expression of circular RNAs (circRNAs) has previously been investigated in breast cancer. However, little is known about the effects of drugs on their regulation and relationship with the cognate linear transcript (linRNA). We analyzed the dysregulation of both 12 cancer-related circRNAs and their linRNAs in two breast cancer cell lines undergoing various treatments. We selected 14 well-known anticancer agents affecting different cellular pathways and examined their impact. Upon drug exposure circRNA/linRNA expression ratios increased, as a result of the downregulation of linRNA and upregulation of circRNA within the same gene. In this study, we highlighted the relevance of identifying the drug-regulated circ/linRNAs according to their oncogenic or anticancer role. Interestingly, VRK1 and MAN1A2 were increased by several drugs in both cell lines. However, they display opposite effects, circ/linVRK1 favors apoptosis whereas circ/linMAN1A2 stimulates cell migration, and only XL765 did not alter the ratio of other dangerous circ/linRNAs in MCF-7. In MDA-MB-231 cells, AMG511 and GSK1070916 decreased circGFRA1, as a good response to drugs. Furthermore, some circRNAs might be associated with specific mutated pathways, such as the PI3K/AKT in MCF-7 cells with circ/linHIPK3 correlating to cancer progression and drug-resistance, or NHEJ DNA repair pathway in TP-53 mutated MDA-MB-231 cells.

Hsa_circ_0060467 promotes breast cancer liver metastasis by complexing with eIF4A3 and sponging miR-1205

Breast cancer (BC) is the most common cancer and the top cause of female mortality worldwide. The prognosis for patients with breast cancer liver metastasis (BCLM) remains poor. Emerging studies suggest that circular RNAs (circRNAs) are associated with the progression of BC. Exploration of circRNAs presents a promising avenue for identifying metastasis-targeting agents and improving the prognosis of patients with BCLM. Microarray and bioinformatic analyses were used to analyze differentially expressed circRNAs between three pairs of BCLM and primary BC. The roles of hsa_circ_0060467 (circMYBL2) and its target gene E2F1 in BC cells were explored by multiple functional experiments. And xenograft mouse models and hepatic metastases of BC hemi-spleen models were used to illustrate the function of circMYBL2 in vivo. The intrinsic molecular mechanism involving circMYBL2 was confirmed by bioinformatics analyses, RIP assays, CHIRP assays, luciferase reporter assays, and rescue experiments. CircMYBL2 was overexpressed in BCLM tissues and BC cells. Functionally, circMYBL2 can facilitate the proliferation and liver metastasis of BC. Mechanistically, circMYBL2 upregulated the transcription factor E2F1 by sponging miR-1205 and complexing with eukaryotic translation initiation factor 4A3 (eIF4A3) and then facilitated the epithelial-mesenchymal transition (EMT) process in BC cells. Our findings showed that circMYBL2 promoted the tumorigenesis and aggressiveness of BC through the circMYBL2/miR-1205/E2F1 and circMYBL2/eIF4A3/E2F1 axes, which may provide a novel targeted therapy for patients with BCLM.

Exosomal circular RNAs: A chief culprit in cancer chemotherapy resistance

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

CRISPR/Cas genome editing in triple negative breast cancer: Current situation and future directions

Triple negative breast cancer (TNBC) has been well-known to be closely associated with the abnormal expression of both oncogenes and tumor suppressors. Although several pathogenic mutations in TNBC have been identified, the current therapeutic strategy is usually aimed at symptom relief rather than correcting mutations in the DNA sequence. Of note, clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) has been gradually regarded as a breakthrough gene-editing tool with potential therapeutic applications in human cancers, including TNBC. Thus, in this review, we focus on summarizing the molecular subtypes of TNBC, as well as the CRISPR system and its potential applications in TNBC treatment. Moreover, we further discuss several emerging strategies for utilizing the CRISPR/Cas system to aid in the precise diagnosis of TNBC, as well as the limitations of the CRISPR/Cas system. Taken together, these findings would demonstrate that CRISPR/Cas system is not only an effective genome editing tool in TNBC, but a promising strategy for the future therapeutic purposes.

New progress in the role of microRNAs in the diagnosis and prognosis of triple negative breast cancer

Triple negative breast cancer is distinguished by its high malignancy, aggressive invasion, rapid progression, easy recurrence, and distant metastases. Additionally, it has a poor prognosis, a high mortality, and is unresponsive to conventional endocrine and targeted therapy, making it a challenging problem for breast cancer treatment and a hotspot for scientific research. Recent research has revealed that certain miRNA can directly or indirectly affect the occurrence, progress and recurrence of TNBC. Their expression levels have a significant impact on TNBC diagnosis, treatment and prognosis. Some miRNAs can serve as biomarkers for TNBC diagnosis and prognosis. This article summarizes the progress of miRNA research in TNBC, discusses their roles in the occurrence, invasion, metastasis, prognosis, and chemotherapy of TNBC, and proposes a treatment strategy for TNBC by interfering with miRNA expression levels.

RNA therapeutics: updates and future potential

Recent advancements in the production, modification, and cellular delivery of RNA molecules facilitated the expansion of RNA-based therapeutics. The increasing understanding of RNA biology initiated a corresponding growth in RNA therapeutics. In this review, the general concepts of five classes of RNA-based therapeutics, including RNA interference-based therapies, antisense oligonucleotides, small activating RNA therapies, circular RNA therapies, and messenger RNA-based therapeutics, will be discussed. Moreover, we also provide an overview of RNA-based therapeutics that have already received regulatory approval or are currently being evaluated in clinical trials, along with challenges faced by these technologies. RNA-based drugs demonstrated positive clinical trial results and have the ability to address previously "undruggable" targets, which delivers great promise as a disruptive therapeutic technology to fulfill its full clinical potentiality.

Current evidence on circRNAs as potential theranostic markers for detecting chemoresistance in breast cancer: a systematic review and meta‑analysis

This study assessed the value of circRNAs (circular RNAs) as prognostic markers in BC (breast cancer). We searched pertinent studies on the PubMed, Embase, and Web of Science online databases published according to PRISMA guidelines. A random-effects model for meta-analysis was used to assess the combined effect size of the HRs (hazard ratios) of the included studies. The heterogeneity test used Cochran's Q-test and I² statistics. Thirty of the 520 trials retrieved were included in the systematic review. A total of 11 chemotherapeutic agents were used in the included studies. A total of 30 studies on 30 circRNAs were included in the systematic review. Of the 30 relevant circRNAs, 28 were upregulated and two were downregulated in breast cancer versus normal samples, and both were associated with increased drug resistance. Nine of 30 studies were used for the meta-analysis. The results of the meta-analysis showed that the groups with circRNA upregulation and circRNA downregulation showed the same prognostic risk (HR = 1.37, 95% Cl: 0.80-2.36, I² = 63.7%). The results of subgroup analysis showed that both upregulated circRNAs (HR = 2.24, 95% Cl: 1.34-3.75, I² = 0%) and downregulated circRNAs (HR = 0.61, 95% Cl: 0.45-0.83, I² = 0%) were associated with poor BC prognosis. Collectively, the results of all relevant articles collected indicated that circRNAs showed good potential as possible clinical biomarkers of chemoresistance in BC patients.

Circular RNAs as prognostic and diagnostic biomarkers in renal cell carcinoma

Background

Circular RNAs (circRNAs) play pivotal roles in proliferation, apoptosis, migration, and invasion of renal cell carcinoma (RCC) cells. This study is aimed to systematically summarize the current evidence regarding the clinical implications of circRNAs in RCC patients.

Methods

A systematic search in PubMed, Embase, and Web of Science was performed until January 1, 2022. The correlation between the expression of circRNAs and clinicopathological, prognostic, and diagnostic features of RCC was evaluated using the meta‐analysis.

Results

Ultimately, 41 studies with 3485 RCC patients were included in this study: 26 studies for clinicopathological features, 31 studies for prognosis, and eight studies for diagnosis. Altered expression of circRNAs was significantly associated with clinicopathological characteristics of RCC, including tumor size, tumor stage, lymph node metastasis, distant metastasis, and TNM stage. The tumor promoter circRNAs were associated with reduced overall survival (OS) (Hazard Ratio (HR) = 1.98, 95% confidence interval [CI] 1.68–2.34) and disease/progression/recurrence‐free survival (DFS/PFS/RFS) (HR = 2.34, 95% CI 1.85–2.97). Contrarily, the tumor suppressor circRNAs were linked with better OS (HR = 0.49, 95% CI 0.40–0.60) and DFS/PFS/RFS (HR = 0.40, 95% CI 0.28–0.59). The pooled sensitivity and specificity of circRNAs for RCC diagnosis in tissue samples were both 0.84. These results in fluid samples (serum and urine) were 0.78 and 0.69, respectively.

Conclusion

CircRNAs can serve as promising diagnostic and prognostic biomarkers for RCC.

The function and regulatory mechanism of RNA-binding proteins in breast cancer and their future clinical treatment prospects

Breast cancer is the most common female malignancy, but the mechanisms regulating gene expression leading to its development are complex. In recent years, as epigenetic research has intensified, RNA-binding proteins (RBPs) have been identified as a class of posttranscriptional regulators that can participate in regulating gene expression through the regulation of RNA stabilization and degradation, intracellular localization, alternative splicing and alternative polyadenylation, and translational control. RBPs play an important role in the development of normal mammary glands and breast cancer. Functional inactivation or abnormal expression of RBPs may be closely associated with breast cancer development. In this review, we focus on the function and regulatory mechanisms of RBPs in breast cancer, as well as the advantages and challenges of RBPs as potential diagnostic and therapeutic targets in breast cancer, and discuss the potential of RBPs in clinical treatment.

Non-coding RNAs in skin cancers:Biological roles and molecular mechanisms

Cutaneous malignancies, including basal cell carcinoma, cutaneous squamous cell carcinoma, and cutaneous melanoma, are common human tumors. The incidence of cutaneous malignancies is increasing worldwide, and the leading cause of death is malignant invasion and metastasis. The molecular biology of oncogenes has drawn researchers’ attention because of the potential for targeted therapies. Noncoding RNAs, including microRNAs, long noncoding RNAs, and circular RNAs, have been studied extensively in recent years. This review summarizes the aspects of noncoding RNAs related to the metastasis mechanism of skin malignancies. Continuous research may facilitate the identification of new therapeutic targets and help elucidate the mechanism of tumor metastasis, thus providing new opportunities to improve the survival rate of patients with skin malignancies.

Target-Initiated Cascade Signal Amplification Lights up a G-Quadruplex for a Label-Free Detection of Circular Ribonucleic Acids

Circular ribonucleic acids (circRNAs) are a type of RNA that originates through back-splicing events from linear primary transcripts. CircRNAs display high structural resistance and tissue specificity. Accurate quantification of the circRNA expression level is of vital importance to disease diagnosis. Herein, we construct a label-free fluorescent biosensor for ultrasensitive analysis of circRNAs based on the integration of target-initiated cascade signal amplification strategy with a light-up G-quadruplex. This assay involves only one assistant probe that targets the circRNA-specific back-splice junction. When circRNA is present, it hybridizes with the assistant probe to initiate the duplex-specific nuclease (DSN)-catalyzed cyclic cleavage reaction, producing abundant triggers with 3'OH termini. Then, terminal deoxynucleotidyl transferase (TdT) catalyzes the addition of dGTP and dATP at the 3'-OH termini of the resultant triggers to obtain abundant long G-rich DNA sequences that can form efficient G-quadruplex products. The addition of Thioflavin T (ThT) can light up G-quadruplex, generating an enhanced fluorescence. This assay may be performed isothermally without the involvement of any nucleic acid templates, exogenous primers, and specific labeled probes. Importantly, this biosensor can discriminate target circRNA from one-base mismatched circRNA and exhibits good performance in human serum. Moreover, it can accurately detect circRNA in cancer cells at a single-cell level and even differentiate the circRNA levels in the tissues of healthy persons and nonsmall cell lung cancer (NSCLC) patients, with promising applications in circRNA-related cancer diagnosis and therapeutics.

CircHGF suppressed cell proliferation and osteogenic differentiation of BMSCs in ONFH via inhibiting miR-25-3p binding to SMAD7

Steroid-induced osteonecrosis of the femoral head (ONFH) is a common and devastating bone disorder, which often results in progressive collapse of the femoral head and subsequent osteoarthritis. The proliferation ability and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) play critical roles in maintaining the structural and functional integrity of the femoral head to prevent ONFH. Until now, little has been known about the underlying mechanism of BMSCs differentiation disorder during ONFH progression. Circular RNAs (circRNAs) are considered to be vital non-coding RNAs functionally involved in various human diseases. However, whether and how circRNA regulates the proliferation and osteogenic differentiation of BMSCs in ONFH remain unclear. In this study, we analyzed the circRNA expression profile of five samples of BMSCs in ONFH and five samples of control by using circRNA microarray assays. We identified 182 differentially expressed circRNAs, among which 108 circRNAs were upregulated. We further investigated the effects of a significantly upregulated circRNA, circHGF, on the proliferation and osteogenic differentiation of BMSCs in vitro. Results showed that circHGF suppressed the proliferation and osteogenic differentiation of BMSCs in ONFH by targeting miR-25-3p/SMAD7 axis. Our findings provided a potential diagnostic and therapeutic strategy for ONFH.

Cost-Effective Transcriptome-Wide Profiling of Circular RNAs by the Improved-tdMDA-NGS Method

Covalently closed circular RNAs are neoteric to the eukaryotic family of long non-coding RNAs emerging as a result of 5′–3′ backsplicing from exonic, intronic, or intergenic regions spanning the parental gene. Owing to their unique structure and stability, circular RNAs have a multitude of functional properties such as micro-RNA and protein sponges, direct and indirect modulators of gene expression, protein translation, and many unproven activities apart from being potential biomarkers. However, due to their low abundance, most of the global circular RNA identification is carried out by high-throughput NGS-based approaches requiring millions of sequencing reads. This lag in methodological advancements demands for newer, more refined, and efficient identification techniques. Here, we aim to show an improved version of our previously reported template-dependent multiple displacement amplification (tdMDA)-NGS method by superimposing the ribosomal depletion step and use of H minus reverse transcriptase and RNase H. Implication of tdMDA using highly replicative Phi29 DNA polymerase after minimizing the linear and ribosomal RNA content further intensifies its detection limit toward even the abysmally expressing circular RNA at a low NGS depth, thereby decreasing the cost of identifying a single circular RNA. A >11-fold and >6-fold increase in total circular RNA was identified from the improved-tdMDA-NGS method over the traditional method of circRNA sequencing using DCC and CIRI2 pipelines, respectively, from Oryza sativa subsp. Indica. Furthermore, the reliability of the improved-tdMDA-NGS method was also asserted in HeLa cell lines, showing a significant fold difference in comparison with the existing traditional method of circRNA sequencing. Among the identified circular RNAs, a significant percentage from both rice (∼58%) and HeLa cell lines (∼84%) is found to be matched with the previously reported circular RNAs, suggesting that the improved-tdMDA-NGS method can be adapted to detect and characterize the circular RNAs from different biological systems.

Circular RNAs as Potential Biomarkers in Breast Cancer

Due to the high heterogeneity and initially asymptomatic nature of breast cancer (BC), the management of this disease depends on imaging together with immunohistochemical and molecular evaluations. These tests allow early detection of BC and patient stratification as they guide clinicians in prognostication and treatment decision-making. Circular RNAs (circRNAs) represent a class of newly identified long non-coding RNAs. These molecules have been described as key regulators of breast carcinogenesis and progression. Moreover, circRNAs play a role in drug resistance and are associated with clinicopathological features in BC. Accumulating evidence reveals a clinical interest in deregulated circRNAs as diagnostic, prognostic and predictive biomarkers. Furthermore, due to their covalently closed structure, circRNAs are highly stable and easily detectable in body fluids, making them ideal candidates for use as non-invasive biomarkers. Herein, we provide an overview of the biogenesis and pleiotropic functions of circRNAs, and report on their clinical relevance in BC.

Emerging Role and Mechanism of circRNAs in Pediatric Malignant Solid Tumors

Circular RNAs (circRNAs) are non-coding RNAs with covalent closed-loop structures and are widely distributed in eukaryotes, conserved and stable as well as tissue-specific. Malignant solid tumors pose a serious health risk to children and are one of the leading causes of pediatric mortality. Studies have shown that circRNAs play an important regulatory role in the development of childhood malignant solid tumors, hence are potential biomarkers and therapeutic targets for tumors. This paper reviews the biological characteristics and functions of circRNAs as well as the research progress related to childhood malignant solid tumors.

circular RNAs 0000515 and 0011385 as potential biomarkers for disease monitoring and determining prognosis in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is extremely fatal and potential biomarkers for precision medicine of patients with PDAC are yet to be elucidated. Moreover, the clinical values of circular RNAs (circRNAs) in PDAC management are yet to be investigated. The aim of the present study was to perform a secondary analysis of two PDAC public datasets (GSE69362 and GSE79634), to identify the candidate circRNAs, to validate the expression of these circRNAs, and to determine their association with the clinicopathological characteristics and survival of patients with PDAC. A total of 60 patients with PDAC were retrospectively reviewed in the present study. The expression levels of these candidate circRNAs were detected in PDAC tissues and paired adjacent normal tissues via reverse transcription-quantitative PCR analysis. In addition, the clinicopathological characteristics and overall survival (OS) of patients with PDAC were recorded. Bioinformatics analysis identified 22 overlapping differentially expressed (DE) circRNAs between the GSE69362 and GSE79634 datasets, among which nine DEcircRNAs with accordant expression trends (the DEcircRNAs that were upregulated or downregulated in tumor tissues compared with paired adjacent normal tissues in both datasets) were selected as candidate circRNAs, including circ_0000515, circ_0000517, circ_0000520, circ_0000514, circ_0011385, circ_0055033, circ_0072088, circ_0003528 and circ_0008514. In the 60 patients with PDAC, the expression levels of circ_0000515, circ_0000517, circ_0000520, circ_0000514, circ_0011385, circ_0055033, circ_0072088 and circ_0003528 were notably upregulated in PDAC tissues compared with paired adjacent normal tissues. Furthermore, circ_0000515, circ_0000520, circ_0000514, circ_0011385 and circ_0072088 were positively associated with T stage, N stage and/or TNM stage in patients with PDAC. Notably, circ_0000515 and circ_0011385 were negatively associated with OS in patients with PDAC. Taken together, the results of the present study suggest that circ_0000515 and circ_0011385 may serve as prognostic biomarkers for patients with PDAC.

Recent advances of nanotechnology in the diagnosis and therapy of triple-negative breast cancer (TNBC)

BACKGROUND

The development of advanced treatment of triple-negative breast cancer (TNBC) is the utmost need of an era. TNBC is recognized as the most aggressive, metastatic cancer and the leading cause of mortality in females worldwide. The lack of expression of triple receptors namely, estrogen, progesterone, and human epidermal receptor2 defined TNBC.

OBJECTIVE

The current review introduced the novel biomarkers such as miRNA and family, PD1, EGFR, VEGF, TILs, P53, AR and PI3K, etc. contributed significantly to the prognosis and diagnosis of TNBC. Once diagnosed the utilization advanced approaches available for TNBC because of the limitations of chemotherapy. Novel approaches include lipid-based (liposomes, SLN, NLC, and SNEDDS), polymer-based (micelle, nanoparticles, dendrimers, and quantum dots), advanced nanocarriers such as (exosomes, antibody and peptide-drug conjugates), carbon-based nanocarriers (Carbon nanotubes, and graphene oxide). Lipid-based delivery is used for excellent carriers for hydrophobic drugs, biocompatibility, and lesser systemic toxicities than chemotherapeutic agents. Polymer-based approaches are preferred over lipids for providing longer circulation time, nanosize, high loading efficiency, high linking; avoiding the expulsion of drugs, targeted action, diagnostic and biosensing abilities. Advanced approaches like exosomes, conjugated moieties are preferred over polymeric for possessing potency, high penetrability, biomarkers, and avoiding the toxicity of tissues. Carbon-based gained wide applicability for their unique properties like a versatile carrier, prognostic, diagnostic, sensing, photodynamic, and photothermal characteristics.

CONCLUSION

The survival rate can be increased by utilizing several kinds of biomarkers. The advanced approaches can also be significantly useful in the prognosis and theranostic of triple-negative breast cancer. One of the biggest successes in treating with nanotechnology-based approaches is the marked reduction of systemic toxicity with high therapeutic effectiveness compared with chemotherapy, surgery, etc. The requirements such as prompt diagnosis, longer circulation time, high efficiency, and high potency, can be fulfilled with these nanocarriers.

Exosomes in triple negative breast cancer: From bench to bedside

Exosomes are lipid bilayer extracellular vesicles with a size of 30-150 nm, which can be released by various types of cells including breast cancer cells. Exosomes are enriched with multiple nucleic acids, lipids, proteins and play critical biological roles by binding to recipient cells and transmitting various biological cargos. Studies have reported that tumor-derived exosomes are involved in cancer initiation and progression, such as promoting cancer invasion and metastasis, accelerating angiogenesis, contributing to epithelial-mesenchymal transition, and enhancing drug resistance in tumors. Recently the dysregulating of exosomes has been found in triple-negative breast cancer (TNBC), relating to the clinicopathological characteristics and prognosis of TNBC patients. Considering the poor prognosis and lack of adequate response to conventional therapy of TNBC, the discovery of certain exosomes as a new target for diagnosis and treatment of TNBC may be a good choice that provides new opportunities for the early diagnosis, clinical treatment of TNBC. Here, we first discuss the innovative prognostic and predictive effects of exosomes on TNBC, as well as the practical clinical problems. Secondly, we focus on the new therapeutic areas represented by exosomes, especially the impact of introducing exosomes in TNBC treatment in the future.

Research Progress of circRNAs in Glioblastoma

Circular RNAs (circRNAs) are a class of single-stranded covalently closed non-coding RNAs without a 5' cap structure or 3' terminal poly (A) tail, which are expressed in a variety of tissues and cells with conserved, stable and specific characteristics. Glioblastoma (GBM) is the most aggressive and lethal tumor in the central nervous system, characterized by high recurrence and mortality rates. The specific expression of circRNAs in GBM has demonstrated their potential to become new biomarkers for the development of GBM. The specific expression of circRNAs in GBM has shown their potential as new biomarkers for GBM cell proliferation, apoptosis, migration and invasion, which provides new ideas for GBM treatment. In this paper, we will review the biological properties and functions of circRNAs and their biological roles and clinical applications in GBM.

Human disease biomarker panels through systems biology

As more uses for biomarkers are sought after for an increasing number of disease targets, single-target biomarkers are slowly giving way for biomarker panels. These panels incorporate various sources of biomolecular and clinical data to guarantee a higher robustness and power of separation for a clinical test. Multifactorial diseases such as psychiatric disorders show great potential for clinical use, assisting medical professionals during the analysis of risk and predisposition, disease diagnosis and prognosis, and treatment applicability and efficacy. More specific tests are also being developed to assist in ruling out, distinguishing between, and confirming suspicions of multifactorial diseases, as well as to predict which therapy option may be the best option for a given patient's biochemical profile. As more complex datasets are entering the field, involving multi-omic approaches, systems biology has stepped in to facilitate the discovery and validation steps during biomarker panel generation. Filtering biomolecules and clinical data, pre-validating and cross-validating potential biomarkers, generating final biomarker panels, and testing the robustness and applicability of those panels are all beginning to rely on machine learning and systems biology and research in this area will only benefit from advances in these approaches.