Expression profiles, biological functions and clinical significance of circRNAs in bladder cancer

A dual-signal biosensor based on surface-enhanced Raman spectroscopy for high-sensitivity quantitative detection and imaging of circRNA in living cells

Circular RNAs (circRNAs) are non-coding RNAs that play key roles in the development and progression of cancer through various mechanisms of action, making them promising biomarkers for cancer diagnosis, prognosis, and treatment. In the present study, a biosensor based on surface-enhanced Raman spectroscopy (SERS) was developed for rapid, simple, and sensitive quantitative detection of intracellular circRNAs for the first time. A dual-signal SERS nanoprobe with a 4MBN and ROX signal molecule was fabricated, and the ROX signal intensity was used to determine the concentration of target circSATB2. 4MBN was used as an internal standard to calibrate the ROX signal, thereby achieving highly sensitive and reliable detection of the target circRNA with a limit of detection of 0.043 pM. Furthermore, the relatively high expression of circSATB2 in lung cancer cells compared to that in normal lung epithelial cells was successfully characterized by the proposed SERS imaging method, which is consistent with the results of standard reverse transcription-polymerase chain reaction (RT-PCR). Monitoring of specific circRNAs using this SERS-based biosensor is a promising method for cancer diagnosis and gene therapy.

circICMT upregulates and suppresses the malignant behavior of bladder cancer

BACKGROUND

Circular RNA (circRNA) is a new type of endogenous single-stranded RNA with a covalently closed circular structure. Increasing evidence shows that circRNA plays an important role in regulating gene expression in tumors. circICMT is a circular RNA produced by the ICMT gene. Currently, the molecular function of circICMT in bladder cancer remains unclear.

METHOD

Differentially expressed circRNAs were identified from RNA sequencing data and circICMT was identified as a new candidate circRNA. qRT-PCR and sanger sequencing were used to detect the expression of circICMT in bladder cancer tissue specimens. Stable cell lines overexpressing and knocking down circICMT were constructed to explore the effect of circICMT on bladder cancer cells. Its biological effects were detected through wound healing experiments, colony formation experiments, CCK-8 experiments and xenogeneic tumorigenesis experiments.

RESULT

This study found that circICMT was significantly upregulated in bladder cancer tissue specimens. Overexpression of circICMT can inhibit cell migration, proliferation and colony formation ability, while knockdown of circICMT promotes the malignant phenotype of bladder cancer cells. Bioinformatics predictions have found that circICMT can bind to a variety of miRNAs and RBPs and may form a complex regulatory network to regulate the progression of bladder cancer.

CONCLUSION

circICMT is significantly highly expressed in bladder cancer, and intervening circICMT expression affects the malignant phenotype of bladder cancer cells in vivo and in vitro, which may provide potential biomarkers and therapeutic targets for the management of bladder cancer.

Noncoding RNA, friend or foe for nephrolithiasis?

Nephrolithiasis is one of the most common diseases in urology, characterized by notable incidence and recurrence rates, leading to significant morbidity and financial burden. Despite its prevalence, the precise mechanisms underlying stone formation remain incompletely understood, thus hindering significant advancements in kidney stone management over the past three decades. Investigating the pivotal biological molecules that govern stone formation has consistently been a challenging and high-priority task. A significant portion of mammalian genomes are transcribed into noncoding RNAs (ncRNAs), which have the ability to modulate gene expression and disease progression. They are thus emerging as a novel target class for diagnostics and pharmaceutical exploration. In recent years, the role of ncRNAs in stone formation has attracted burgeoning attention. They have been found to influence stone formation by regulating ion transportation, oxidative stress injury, inflammation, osteoblastic transformation, autophagy, and pyroptosis. These findings contributes new perspectives on the pathogenesis of nephrolithiasis. To enhance our understanding of the diagnostic and therapeutic potential of nephrolithiasis-associated ncRNAs, we summarized the expression profiles, biological functions, and clinical significance of these ncRNAs in the current review.

Role of non-coding RNA in lineage plasticity of prostate cancer

The treatment of prostate cancer (PCa) has made great progress in recent years, but treatment resistance always develops and can even lead to fatal disease. Exploring the mechanism of drug resistance is of great significance for improving treatment outcomes and developing biomarkers with predictive value. It is increasingly recognized that mechanism of drug resistance in advanced PCa is related to lineage plasticity and tissue differentiation. Specifically, one of the mechanisms by which castration-resistant prostate cancer (CRPC) cells acquire drug resistance and transform into neuroendocrine prostate cancer (NEPC) cells is lineage plasticity. NEPC is a subtype of PCa that is highly aggressive and lethal, with a median survival of only 7 months. With the development of high-throughput RNA sequencing technology, more and more non-coding RNAs have been identified, which play important roles in different diseases through different mechanisms. Several ncRNAs have shown great potential in PCa lineage plasticity and as biomarkers. In the review, the role of ncRNA in PCa lineage plasticity and its use as biomarkers were reviewed.

Circular RNA TAF4B targeting MFN2 accelerates cell growth in bladder cancer through p27 depression and AKT activation

Introduction

Bladder cancer (BCa) is a common malignancy in the urinary tract. It has high recurrence rates and often requires microscopic examination, which presents significant challenges in clinical treatment. Previous research has shown that circular TAF4B (circTAF4B) is significantly upregulated in BCa and is associated with a poor prognosis. However, the specific targets and molecular mechanisms by which circTAF4B functions in BCa are still not well - understood.

Methods

In this study, an RNA pull - down assay and mass spectrometry were utilized to identify MFN2 as a binding protein of circTAF4B. Additionally, siRNA was used to silence MFN2 to observe the amplification of the inhibitory effects of circTAF4B overexpression on cell growth and migration in BCa cells. Moreover, circTAF4B shRNA lentiviral particles were employed to study their impact on BCa progression by examining the regulation of p27 and the blocking of AKT signaling.

Results

It was found that MFN2 is a binding protein of circTAF4B. Silencing MFN2 with siRNA enhanced the inhibitory effects of circTAF4B overexpression on cell growth and migration in BCa cells. Also, circTAF4B shRNA lentiviral particles inhibited BCa progression by upregulating p27 and blocking AKT signaling.

Discussion

In conclusion, the physical binding of circTAF4B to MFN2 is a crucial process in the tumorigenesis and progression of BCa. Targeting circTAF4B or its complexes may have potential as a therapeutic strategy for BCa diagnosis and treatment.

Therapeutic importance and diagnostic function of circRNAs in urological cancers: from metastasis to drug resistance

Circular RNAs (circRNAs) are a member of non-coding RNAs with no ability in encoding proteins and their aberrant dysregulation is observed in cancers. Their closed-loop structure has increased their stability, and they are reliable biomarkers for cancer diagnosis. Urological cancers have been responsible for high mortality and morbidity worldwide, and developing new strategies in their treatment, especially based on gene therapy, is of importance since these malignant diseases do not respond to conventional therapies. In the current review, three important aims are followed. At the first step, the role of circRNAs in increasing or decreasing the progression of urological cancers is discussed, and the double-edged sword function of them is also highlighted. At the second step, the interaction of circRNAs with molecular targets responsible for urological cancer progression is discussed, and their impact on molecular processes such as apoptosis, autophagy, EMT, and MMPs is highlighted. Finally, the use of circRNAs as biomarkers in the diagnosis and prognosis of urological cancer patients is discussed to translate current findings in the clinic for better treatment of patients. Furthermore, since circRNAs can be transferred to tumor via exosomes and the interactions in tumor microenvironment provided by exosomes such as between macrophages and cancer cells is of importance in cancer progression, a separate section has been devoted to the role of exosomal circRNAs in urological tumors.

The role of circular RNA during the urological cancer metastasis: exploring regulatory mechanisms and potential therapeutic targets

Metastasis is a major contributor to treatment failure and death in urological cancers, representing an important biomedical challenge at present. Metastases form as a result of cancer cells leaving the primary site, entering the vasculature and lymphatic vessels, and colonizing clones elsewhere in the body. However, the specific regulatory mechanisms of action underlying the metastatic process of urological cancers remain incompletely elucidated. With the deepening of research, circular RNAs (circRNAs) have been found to not only play a significant role in tumor progression and prognosis but also show aberrant expression in various tumor metastases, consequently impacting tumor metastasis through multiple pathways. Therefore, circRNAs are emerging as potential tumor markers and treatment targets. This review summarizes the research progress on elucidating how circRNAs regulate the urological cancer invasion-metastasis cascade response and related processes, as well as their role in immune microenvironment remodeling and circRNA vaccines. This body of work highlights circRNA regulation as an emerging therapeutic target for urological cancers, which should motivate further specific research in this regard.

CircPGM5 regulates Foxo3a phosphorylation via MiR-21-5p/MAPK10 axis to inhibit bladder cancer progression

Bladder cancer (BC) is one of the most prevalent malignant tumors worldwide, and the incidence is especially higher in males. Extensive evidence has demonstrated the pivotal role of circular RNAs (circRNAs) in BC progression. However, the exact regulatory mechanism of circRNAs in BC remains incompletely elucidated and warrants further exploration. This study screened a novel circRNA-circPGM5 from thousands of circRNAs by high-throughput sequencing. We found that circPGM5, originating from the PGM5 gene, was significantly lower expressed in BC tissues. Quantitative real-time PCR (qRT-PCR) verified that circPGM5 showed relatively low expression in 50 pairs of BC tissues and EJ and T24 cells. Notably, circPGM5 expression was correlated with stage, grade, and lymphatic metastasis of BC. Through RNA-FISH assay, we confirmed that circPGM5 predominantly localized in the cytoplasm. Functionally, overexpression of circPGM5 inhibited the proliferation, migration, and invasion of BC cells in vitro. Remarkably, circPGM5 demonstrated markedly significant tumor growth and metastasis suppression in vivo. Mechanistically, we discovered that circPGM5 upregulated the mitogen-activated protein kinase 10 (MAPK10) expression by influencing the oncogenic miR-21-5p activity through miR-21-5p absorption. This modulation of MAPK10 impacted the phosphorylation of the tumor suppressor Foxo3a in BC. In conclusion, our findings uncovered the tumor-suppressing role of circPGM5 in BC via the miR-21-5p/MAPK10/Foxo3a axis.

IGF2BP2-modified circular RNA circCHD7 promotes endometrial cancer progression via stabilizing PDGFRB and activating JAK/STAT signaling pathway

Circular RNAs (circRNAs) represent a class of covalently closed, single-stranded RNAs and have been linked to cancer progression. N6-methyladenosine (m6A) methylation is a ubiquitous RNA modification in cancer cells. Increasing evidence suggests that m6A can mediate the effects of circRNAs in cancer biology. In contrast, the post-transcriptional systems of m6A and circRNA in the progression of endometrial cancer (EC) remain obscure. The current study identified a novel circRNA with m6A modification, hsa_circ_0084582 (circCHD7), which was upregulated in EC tissues. Functionally, circCHD7 was found to promote the proliferation of EC cells. Mechanistically, circCHD7 interacted with insulin-like growth factor 2 mRNA-binding protein (IGF2BP2) to amplify its enrichment. Moreover, circCHD7 increased the mRNA stability of platelet-derived growth factor receptor beta (PDGFRB) in an m6A-dependent manner, thereby enhancing its expression. In addition, the circCHD7/IGF2BP2/PDGFRB axis activated the JAK/STAT signaling pathway and promoted EC cell proliferation. In conclusion, these findings provide new insights into the regulation of circRNA-mediated m6A modification, and the new "circCHD7-PDGFRB" model of regulation offers new perspectives on circCHD7 as a potential target for EC therapy.

Non-coding RNA in exosomes: Regulating bone metastasis of lung cancer and its clinical application prospect

Lung cancer is a highly prevalent malignancy with poor prognosis and rapid progression. It most frequently metastasizes to the bone, where it can pose a severe threat to the patient's survival. Once metastasized, the disease is often incurable and can result in severe complications such as hypercalcemia, bone pain, fractures, spinal cord compression, and subsequent paralysis. Exosomes are bilayer vesicle nanoparticles secreted by most of the extracellular vesicles, which can be found in almost all organisms and play an essential role in intercellular communication. Through their ability to regulate related bone cells, exosomes carry bioactive molecules, including proteins, lipids, and non-coding RNAs (ncRNAs), that can be extremely important in bone remodeling. Studies have been conducted on the role play by proteins, lncRNA, and microRNA-all ncRNAs-carried by exosomes in the bone metastases of lung cancer. In this review, the latest progress of the regulatory mechanism of ncRNAs carried by exosomes in lung cancer bone metastasis has been reviewed. The clinical use of exosomes as a promising biomarker, drug transporter, and therapeutic target was highlighted to offer a novel diagnostic and treatment approach for patients with lung cancer bone metastases.

The Traces of Dysregulated lncRNAs-Associated ceRNA Axes in Retinoblastoma: A Systematic Scope Review

PURPOSE

Long non-coding RNAs are an essential component of competing endogenous RNA regulatory axes and play their role by sponging microRNAs and interfering with the regulation of gene expression. Because of the broadness of competing endogenous RNA interaction networks, they may help investigate treatment targets in complicated disorders.

METHODS

This study performed a systematic scoping review to assess verified loops of competing endogenous RNAs in retinoblastoma, emphasizing the competing endogenous RNAs axis related to long non-coding RNAs. We used a six-stage approach framework and the PRISMA guidelines. A systematic search of seven databases was done to locate suitable papers published before February 2022. Two reviewers worked independently to screen articles and collect data.

RESULTS

Out of 363 records, fifty-one articles met the inclusion criteria, and sixty-three axes were identified in desired articles. The majority of the research reported several long non-coding RNAs that were experimentally verified to act as competing endogenous RNAs in retinoblastoma: XIST/NEAT1/MALAT1/SNHG16/KCNQ1OT1, respectively. At the same time, around half of the studies investigated unique long non-coding RNAs.

CONCLUSIONS

Understanding the many features of this regulatory system may aid in elucidating the unknown etiology of Retinoblastoma and providing novel molecular targets for therapeutic and clinical applications.

A meta-analysis of UCA1 accuracy in the detection of bladder cancer

INTRODUCTION

Bladder cancer (BCa) exhibits a relatively high prevalence, yet convenient tools for its early detection are lacking. Our study aims to assess the diagnostic value of Urothelial Carcinoma-Associated 1 (UCA1) in the early detection of BCa.

METHODS

Systematic searches were performed in electronic databases (PubMed, Web of Science, Science Direct, CNKI, Wanfang, and VIP) until 20 July 2023. QUADAS-2 was used for quality assessment, while Meta-DiSc 1.4 and STATA 14.0 were employed for statistical analysis.

RESULTS

A total of 1252 BCa patients and 779 controls, from 12 identified articles, were included. UCA1 showed strong discriminatory ability in BCa detection, with an overall sensitivity of 0.84 specificity of 0.91, and a 0.91 area under the curve (AUC). Strikingly, UCA1 expressed in urine and tissue exhibited higher diagnostic value (0.92 AUC) compared to that in blood (0.86 AUC). Furthermore, urine UCA1 demonstrated remarkable diagnostic performance with 91% sensitivity and 98% specificity. Deeks' funnel plot detected no substantial publication bias.

CONCLUSION

UCA1 could serve as a potential biomarker for BCa detection with good diagnostic performance. Besides, compared to UCA1 in blood, urine and tissue UCA1 exhibited higher diagnostic value. Further prospective clinical research is needed to corroborate the conclusion.

PROSPERO REGISTRATION

CRD42023463210.

Non‑coding RNA: A promising diagnostic biomarker and therapeutic target for esophageal squamous cell carcinoma (Review)

Esophageal cancer (EC) is a common form of malignant tumor in the digestive system that is classified into two types: Esophageal squamous cell carcinomas (ESCC) and esophageal adenocarcinoma. ESCC is known for its early onset of symptoms, which can be difficult to identify, as well as its rapid progression and tendency to develop drug resistance to chemotherapy and radiotherapy. These factors contribute to the high incidence of disease and low cure rate. Therefore, a diagnostic biomarker and therapeutic target need to be identified for ESCC. Non-coding RNAs (ncRNAs) are a class of molecules that are transcribed from DNA but do not encode proteins. Initially, ncRNAs were considered to be non-functional segments generated during transcription. However, with advancements in high-throughput sequencing technologies in recent years, ncRNAs have been associated with poor prognosis, drug resistance and progression of ESCC. The present study provides a comprehensive overview of the biogenesis, characteristics and functions of ncRNAs, particularly focusing on microRNA, long ncRNAs and circular RNAs. Furthermore, the ncRNAs that could potentially be used as diagnostic biomarkers and therapeutic targets for ESCC are summarized to highlight their application value and prospects in ESCC.

Riddle of the Sphinx: Emerging role of circular RNAs in cervical cancer

Cervical cancer is a prominent cause of cancer-related mortality among women, with recent attention directed toward exploring the involvement of circular RNAs (circRNAs) in this particular cancer. CircRNAs, characterized by a covalently closed loop structure, belong to a class of single-stranded non-coding RNA (ncRNA) molecules that play crucial roles in cancer development and progression through diverse mechanisms. The abnormal expression of circRNAs in vivo is significantly associated with the development of cervical cancer. Notably, circRNAs actively interact with miRNAs in cervical cancer, leading to the regulation of diverse signaling pathways, and they can contribute to cancer hallmarks such as self-sufficiency in growth signals, insensitivity to antigrowth signals, limitless proliferation, evading apoptosis, tissue invasion and metastasis, and sustained angiogenesis. Moreover, the distinctive biomedical attributes exhibited by circRNAs, including their abundance, conservation, and stability in body fluids, position them as promising biomarkers for various cancers. In this review, we elucidate the tremendous potential of circRNAs as diagnostic markers or therapeutic targets in cervical cancer by expounding upon their biogenesis, characteristics, functions, and databases, highlighting the novel advances in the signaling pathways associated with circRNAs in cervical cancer.

Role of circular RNA as competing endogenous RNA in ovarian cancer (Review)

Circular RNA (circRNA), a type of non‑coding RNA, plays a regulatory role in biological processes. The special loop structure of circRNA makes it highly stable and specific in diseased tissues and cells, especially in tumors. Competing endogenous RNAs (ceRNAs) compete for the binding of microRNA (miRNA) at specific binding sites and thus regulate gene expression. ceRNAs play an important role in various diseases and are currently recognized as the most prominent mechanism of action of circRNAs. circRNAs can modulate the proliferation, migration, invasion and apoptosis of tumor cells through the ceRNA mechanism. With further research, circRNAs may serve as novel markers and therapeutic targets for ovarian cancer (OC). In the present review, the research progress of circRNAs as ceRNAs in OC was summarized, focusing on the effects of the circRNA/miRNA/mRNA axis on the biological functions of OC cells through mediating pivotal signaling pathways. The role of circRNAs in the diagnosis, prognostic assessment and treatment of OC was also discussed in the present review.

Whole transcriptome sequencing identifies a competitive endogenous RNA network that regulates the immunity of bladder cancer

Several types of non-coding RNAs such as circRNAs, lncRNAs, and miRNAs have been identified to regulate mRNAs through the mechanism known as the competitive endogenous RNA (ceRNA) network. To explore the role of the ceRNA regulatory network in the immune microenvironment of bladder cancer, whole-transcriptome sequencing of bladder tumor and its peritumoral tissues from 38 bladder cancer patients, with a total of 63 samples, was performed to screen differentially expressed circ-, lnc-, mi-, and mRNAs to construct a circ/lnc-mi-mRNA regulatory network with pruning algorithms. We excavated a key immune-related gene BDNF to build the final ceRNA network as hsa-miR-107 sponged by hsa-circ-000211, AC108488.1, and LINC00163. Finally, a meta-analysis of 7 public datasets demonstrated that low expression of BDNF and high expression of hsa-miR-107 were associated with longer survival. Our study identified a ceRNA regulatory network as a potentially new prognostic marker and molecular therapeutic target of bladder cancer.

CircUBE3A(2,3,4,5) promotes adenylate-uridylate-rich binding factor 1 nuclear translocation to suppress prostate cancer metastasis

Metastatic progression is the primary cause of mortality in prostate cancer (PCa) patients. Although circular RNAs (circRNAs) have been implicated in cancer progression and metastasis, our current understanding of their role in PCa metastasis remains limited. In this study, we identified that circUBE3A(2,3,4,5), which originated from exons 2, 3, 4 and 5 of the human ubiquitin-protein ligase E3A (UBE3A) gene, was specifically downregulated in PCa tissues and correlated with the Gleason score, bone metastasis, and D'Amico risk classification. Through the in vitro and in vivo experiments, we demonstrated that overexpression of circUBE3A(2,3,4,5) inhibited PCa cell migration, invasion, metastasis, and proliferation. Mechanistically, circUBE3A(2,3,4,5) was found to bind to adenylate-uridylate-rich binding factor 1 (AUF1), promoting the translocation of AUF1 into the nucleus. This led to decreased AUF1 in the cytoplasm, resulting in methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) mRNA instability and a subsequent reduction at the protein level. The downregulation of MTHFD2 further inhibited vimentin expression, thereby suppressing PCa cell epithelial-mesenchymal transition. Additionally, two pairs of the short-inverted repeats (TSIRs) in flanking introns were identified to synergistically facilitate the generation of circUBE3A(2,3,4,5) and other circRNAs. In summary, TSIRs-induced circUBE3A(2,3,4,5) acts as a suppressor of PCa metastasis by enhancing AUF1 nuclear translocation, reducing MTHFD2, and subsequently inhibiting vimentin expression. This study characterizes circUBE3A(2,3,4,5) as a functional circRNA and proposes it as a highly promising target for preventing PCa metastasis.

Identification of Plasma hsa_circ_0001230 and hsa_circ_0023879 as Potential Novel Biomarkers for Focal Segmental Glomerulosclerosis and circRNA-miRNA-mRNA Network Analysis

INTRODUCTION

Focal segmental glomerulosclerosis (FSGS) is a common glomerulopathy with an unclear mechanism. The demand for FSGS clinical diagnostic biomarkers has not yet been met. Circular RNA (circRNA) is a novel non-coding RNA with multiple functions, but its diagnostic value for FSGS remains unexplored. This study aimed to identify circRNAs that could aid in early clinical diagnosis and to investigate their mechanisms in podocyte injury.

METHODS

The signature of plasma circRNAs for FSGS was identified by circRNA microarray. The existence of circRNAs was confirmed by quantitative real-time polymerase chain reaction (qRT-PCR), RNase R assay, and DNA sequencing. Plasma levels of circRNAs were evaluated by qRT-PCR. The diagnostic value was appraised by the receiver operating characteristic curve. The circRNA-miRNA-mRNA network was built with Cytoscape 7.3.2. Statistically significant differences were calculated by the Mann-Whitney U test.

RESULTS

A total of 493 circRNAs (165 upregulated, 328 downregulated) were differentially expressed in the plasma of FSGS patients (n = 3) and normal controls (n = 3). Eight candidate circRNAs were demonstrated to be circular and stable transcripts. Among them, hsa_circ_0001230 and hsa_circ_0023879 were significantly upregulated in FSGS patients (n = 29) compared to normal controls (n = 51). The areas under the curve value of hsa_circ_0001230 and hsa_circ_0023879 were 0.668 and 0.753, respectively, while that of the two-circRNA panel was 0.763. The RNA pull-down analysis revealed that hsa_circ_0001230 and hsa_circ_0023879 could sponge hsa-miR-106a. Additionally, hsa_circ_0001230 and hsa_circ_0023879 positively regulated hsa-miR-106a target genes phosphatase and tensin homolog (PTEN) and Bcl-2-like protein 11 (BCL2L11) in podocytes.

CONCLUSION

hsa_circ_0001230 and hsa_circ_0023879 are novel blood biomarkers for FSGS. They may regulate podocyte apoptosis by competitively binding to hsa-miR-106a.

CircRAPGEF5 sponges miR-582-3p and targets KIF3A to regulate bladder cancer cell proliferation, migration and invasion

BACKGROUND

Bladder cancer (BCa) is a common malignant disease with high recurrence and poor prognosis. Several circular RNAs (circRNAs) have been found to be associated with the malignant progression of bladder cancer (BCa). Here, the aim of this study was to investigate the expression, role and mechanism of circRAPGEF5 in BCa progression.

METHODS

Quantitative real-time PCR (qRT-PCR) and immunoblotting were used to detect gene and protein expression levels. In vitro functional studies were performed using CCK-8, colony formation, wound healing and Transwell assays, respectively, and a mouse xenograft tumor model was established to perform in vivo experiments. Bioinformatic predictions as well as luciferase reporter assays and RNA pull-down assays were used to probe circRAPGEF5-mediated competitive endogenous RNA (ceRNA) network.

RESULTS

CircRAPGEF5 was significantly overexpressed in BCa patients (p < 0.05), indicating a potential unsatisfactory prognosis. Functionally, knockdown of circRAPGEF5 inhibited the growth, migration and invasion of BCa cells in vitro (p < 0.05), as well as BCa growth in vivo (p < 0.05). Mechanistically, circRAPGEF5 acted as a sponge for miR-582-3p and targeted kinesin family member 3A (KIF3A). In addition, rescue experiments showed that inhibition of miR-582-3p or overexpression of KIF3A reversed the anticancer effects of circRAPGEF5 knockdown on BCa cells (p < 0.05).

CONCLUSION

Silencing circRAPGEF5 inhibits BCa proliferation, migration and invasion via the miR-582-3p/KIF3A axis, demonstrating a promising target for BCa-targeted therapy.

circKDM1A suppresses bladder cancer progression by sponging miR-889-3p/CPEB3 and stabilizing p53 mRNA

Circular RNAs (circRNAs) play crucial biological functions in various tumors, including bladder cancer (BCa). However, the roles and underlying molecular mechanisms of circRNAs in the malignant proliferation of BCa are yet unknown. CircKDM1A was observed to be downregulated in BCa tissues and cells. Knockdown of circKDM1A promoted the proliferation of BCa cells and bladder xenograft growth, while the overexpression of circKDM1A exerts the opposite effect. The dual-luciferase reporter assay revealed that circKDM1A was directly bound to miR-889-3p, acting as its molecular sponge to downregulate CPEB3. In turn, the CPEB3 was bound to the CPE signal in p53 mRNA 3'UTR to stabilize its expression. Thus, circKDM1A-mediated CPEB3 downregulation inhibits the stability of p53 mRNA and promotes BCa malignant progression. In conclusion, circKDM1A functions as a tumor suppressor in the malignant proliferation of BCa via the miR-889-3p/CPEB3/p53 axis. CircKDM1A may be a potential prognostic biomarker and therapeutic target of BCa.

circTADA2A inhibited SLC38A1 expression and suppresses melanoma progression through the prevention of CNBP trans-activation

BACKGROUND

CircTADA2A has been demonstrated to play critical roles in the occurrence and development of human cancer. However, the expression pattern and biological mechanisms of circTADA2A in melanoma remains largely unknown.

METHODS

CircTADA2A were detected by quantitative real-time RT-PCR (qRT-PCR) and validated by Sanger sequencing. Function of circTADA2A and its protein partner in melanoma cells was investigated using RNA interference and overexpression assays. Interaction of circTADA2A, CCHC-type zinc finger nucleic acid binding protein (CNBP) and solute carrier family 38 member 1 (SLC38A1) was confirmed by RNA immunoprecipitation, RNA pull-down, and dual-luciferase reporter assay. The expression of genes and proteins were detected by qRT-PCR and western blot assays.

RESULTS

Data from the investigation showed that a novel circRNA (circTADA2A, hsa_circ_0043278) was markedly downregulated in melanoma cells. Functionally, circTADA2A repressed cell proliferation, migration, invasion in melanoma cells. Mechanistically, circTADA2A interacted with CNBP, acting to suppress the binding of CNBP to the SLC38A1 promoter and subsequently restrained SLC38A1 transcription, which resulting in repression of melanoma progression.

CONCLUSIONS

CircTADA2A suppresses melanoma progression by regulating CNBP/SLC38A1 axis, indicating a potential therapeutic target in melanoma.

circRNA TATA-box binding protein associated factor 15 acts as an oncogene to facilitate bladder cancer progression through targeting miR-502-5p/high mobility group box 3

Circular RNAs (circRNAs) are key in regulating bladder cancer progression. This study explored the effects of circRNA TATA-box binding protein associated factor 15 (circTAF15) on bladder cancer progression. We enrolled 80 bladder cancer patients to examine the relationship between circTAF15 expression and clinical features. The function of circTAF15 on bladder cancer cell viability, proliferation, migration, invasion, and glycolysis was monitored by cell counting kit-8 assay, 5-Ethynyl-2'-deoxyuridine experiment, Transwell experiment, and glycolysis analysis. Dual luciferase reporter gene assay, RNA pull-down assay, and RNA immunoprecipitation assay were used to verify the binding between circTAF15 and miR-502-5p or between miR-502-5p and high mobility group box 3 (HMGB3). circTAF15 effect on in vivo growth of bladder cancer was investigated by xenograft tumor experiment. Quantitative real-time polymerase chain reaction, Western blot, and immunohistochemistry were implemented to investigate the expression levels of genes. circTAF15 was upregulated in bladder cancer patients, associated with unfavorable outcomes. circTAF15 knockdown attenuated bladder cancer cell viability, proliferation, migration, invasion, epithelial-mesenchymal transition, and glycolysis. circTAF15 suppressed miR-502-5p expression, and miR-502-5p inhibited HMGB3 expression. Low miR-502-5p expression was associated with unfavorable outcomes in bladder cancer patients. miR-502-5p silencing and HMGB3 overexpression counteracted the inhibition of circTAF15 knockdown on the malignant phenotype of bladder cancer cells. circTAF15 knockdown attenuated the in vivo growth of bladder cancer cells. circTAF15 enhanced the progression of bladder cancer through upregulating HMGB3 via suppressing miR-502-5p. circTAF15 may be a novel target to treat bladder cancer in the future.

Effects of silencing hsa_circ_0015326 on proliferation, migration, invasion, and apoptosis of epithelial ovarian cancer cells

Although the treatment of ovarian cancer has made great progress, there are still many patients who are not timely detected and given targeted therapy due to unknown pathogenesis. Recent studies have found that hsa_circ_0015326 is upregulated in ovarian cancer and is involved in the proliferation, invasion, and migration of ovarian cancer cells. However, whether hsa_circ_0015326 can be used as a new target of ovarian cancer needs further investigation. Therefore, the effect of hsa_circ_0015326 on epithelial ovarian cancer was investigated in this study. At first, si-hsa_circ_0015326 lentivirus was transfected into epithelial ovarian cancer cells. Then real-time fluorescence quantitative PCR (qRT-PCR) was used to detect hsa_circ_0015326 level. The proliferation of ovarian cancer cells was detected by CCK-8 assay. The horizontal and vertical migration abilities of the cells were detected by wound-healing assay and Transwell assay, respectively. Transwell assay was also used to determine the invasion rate. As for the apoptosis rate, it was assessed by flow cytometry. As a result, the expression level of hsa_circ_0015326 in A2780 and SKOV3 was found to be higher than that in IOSE-80. However, after transfecting si-hsa_circ_0015326 and si-NC into the cells, the proliferation, migration, and invasion abilities of A2780 and SKOV3 cells in the si-hsa_circ_0015326 group were significantly reduced in comparison to those in the si-NC and mock groups, while their apoptosis rates were elevated. Collectively, silencing hsa_circ_0015326 bears the capability of inhibiting the proliferation, migration, and invasion of ovarian cancer cells while increasing apoptosis rate. It can be concluded that hsa_circ_0015326 promotes the malignant biological activities of epithelial ovarian cancer cells.

CircITGA7 regulates malignant phenotypes in bladder cancer cells via targeting miR-330-3p/KLF10 axis

Bladder cancer (BCa) is one of the common malignancies. Circular RNAs (circRNAs) play regulatory roles in cancer progression. CircITGA7 is a circRNA generated from several exons of ITGA7. The potential role of circITGA7 in BCa remains unknown and needs to be explored. Quantitative real time polymerase chain reaction (qRT-PCR) was used to assess circITGA7 and miR-330-3p expression in BCa tissues and cell lines. Kaplan-Meier analysis was used to evaluate the overall survival of these BCa patients. The biological function of circITGA7 was examined by overexpression of circITGA7 using CCK-8, EdU, wound-healing, and Transwell assays. Xenograft assay was performed to further validate the in vitro results. To explore the mechanism of circITGA7, luciferase reporter, RNA pull-down, fluorescence in situ hybridization (FISH) assays were employed to examine the binding interaction among circITGA7, miR-330-3p and kruppel-like factor 10 (KLF10). Western blot was used to study the protein levels of KLF10.CircITGA7 was downregulated in BCa tissues and cell lines and indicated longer overall survival. Moreover, circITGA7 restricted cell proliferation, migration and invasion of BCa through negatively regulating miR-330-3p. The in vivo model showed that circITGA7 influenced the tumor growth. Besides, the overexpression of miR-330-3p promoted cell progression by directly targeting KLF10. Mechanistically, circITGA7 inhibited BCa progression by activating KLF10 via targeting miR-330-3p.CircITGA7 alleviates BCa cell progression via circITGA7/hsa-miR-330-3p/KLF10 axis, which may provide novel therapeutic targets for BCa.

SP2-induced circPUM1 modulates chemoresistance and nature killer cell toxicity in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a type of tumour found in the cavity that is characterized by differentiation and metastasis to the lymph nodes. Although diagnosis strategy and clinical treatment have recently improved, the outcomes for OSCC patients remain unsatisfactory. This study verified the characteristics of circPUM1 in OSCC cells, subsequently generating dysregulated circPUM1 cell models, showing that circPUM1 promoted chemoresistance and natural killer (NK) cell toxicity. Furthermore, the transcription factor SP2 regulated the expression of circPUM1 in OSCC cells, circPUM1 acted as a molecular sponge for miR-770-5p. Moreover, Nucleosome Assembly Protein 1 Like 1 (NAP1L1) is a downstream target for miR-770-5p and essential for circPUM1-mediated cisplatin resistance and NK cell cytotoxicity in OSCC cells. The network composed of SP2, circPUM1, miR-770-5p and NAP1L1 in OSCC appears to be a promising avenue for the development of novel targets for diagnosing or treating OSCC.

New Perspectives on the Role of Liquid Biopsy in Bladder Cancer: Applicability to Precision Medicine

Bladder cancer (BC) is one of the most common tumors in the world. Cystoscopy and tissue biopsy are the standard methods in screening and early diagnosis of suspicious bladder lesions. However, they are invasive procedures that may cause pain and infectious complications. Considering the limitations of both procedures, and the recurrence and resistance to BC treatment, it is necessary to develop a new non-invasive methodology for early diagnosis and multiple evaluations in patients under follow-up for bladder cancer. In recent years, liquid biopsy has proven to be a very useful diagnostic tool for the detection of tumor biomarkers. This non-invasive technique makes it possible to analyze single tumor components released into the peripheral circulation and to monitor tumor progression. Numerous biomarkers are being studied and interesting clinical applications for these in BC are being presented, with promising results in early diagnosis, detection of microscopic disease, and prediction of recurrence and response to treatment.

Exosome-transported of circ_0081069 induces SPIN1 production by binding to miR-195-5p to inhibit radiosensitivity in esophageal squamous cell carcinoma

Circ_0081069 plays a key role in tumor growth; however, its effect on radiosensitivity in esophageal squamous cell carcinoma (ESCC) remains unknown. The study is performed to reveal the association of circ_0081069 expression and radiosensitivity in ESCC and the underlying mechanism. Circ_0081069, miR-195-5p, and spindlin 1 (SPIN1) RNA expression were detected by quantitative real-time polymerase chain reaction. Protein expression was checked by Western blot analysis or immunohistochemistry assay. Cell viability, proliferation, cell apoptosis, migration, and invasion were investigated by cell counting kit-8, 5-Ethynyl-29-deoxyuridine, flow cytometry analysis, scratch test, and transwell assays, respectively. The sensitivity of ESCC cells to radiation was investigated by cell colony formation assay. The interactions among circ_0081069, miR-195-5p, and SPIN1 were identified by dual-luciferase reporter assay and RNA Immunoprecipitation assay. Xenograft mouse model assay was performed to determine the effect of circ_0007841 on radiosensitivity in vivo. Circ_0081069 and SPIN1 expression were upregulated, whereas miR-195-5p was downregulated in ESCC tissues, ESCC cells, and radiation-stimulated ESCC cells. Circ_0081069 silencing inhibited ESCC cell proliferation, invasion, and migration but improved cell apoptosis. In addition, circ_0081069 knockdown enhanced ESCC cell radiosensitivity in vitro and in vivo. Circ_0081069 bound to miR-195-5p and regulated radiosensitivity by binding to miR-195-5p in ESCC cells. Moreover, SPIN1, a target of miR-195-5p, rescued miR-195-5p-mediated effects in ESCC cells. Circ_0081069 was secreted from ESCC cells by being packaged into exosomes. Further, circ_0081069-Exo inhibited radiosensitivity in ESCC cells. Exosome-mediated transfer of circ_0081069 induced SPIN1 production by binding to miR-195-5p, further inhibiting radiosensitivity in ESCC.

CircFSCN1 induces tumor progression and triggers epithelial-mesenchymal transition in bladder cancer through augmentation of MDM2-mediated p53 silencing

BACKGROUND

Compelling evidences indicated that circular RNA (circRNA) was a novel class of non-coding RNA that played critical and distinct roles in various human cancers. Their roles and underlying mechanisms, however, in bladder cancer (BC) remained largely unknown.

METHODS

A novel circRNA derived from oncogene FSCN1, namely circFSCN1, was selected from a microarray analysis. The phenotypic alterations were assessed with functional experiments in vitro and in vivo. RNA immunoprecipitation, RNA pull-down, luciferase reporter assay, and rescue experiments were sequentially proceeded to clarify the interactions among circFSCN1, miR-145-5p, MDM2, and p53.

RESULTS

We observed that the expression of circFSCN1 was elevated in BC cell lines and tissues. Next, we validated the fundamental properties of circFSCN1. In the meanwhile, we noticed that elevated circFSCN1 level, pathological T stage, and tumor grade were identified as independent factors associated with cancer-specific survivals of patients with BC，as determined by univariate and multivariable COX regression analyses. Phenotype studies demonstrated the promoting effects of circFSCN1 on the proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of BC cells. Mechanistically, we elucidated that circFSCN1, primarily localized in the cytoplasm, upregulated the expression of MDM2, a well-known inhibitor of p53, by directly binding to miR-145-5p.

CONCLUSIONS

Elevated circFSCN1 induces tumor progression and EMT in BC via enhancing MDM2-mediated silencing of p53 by sponging miR-145-5p. Targeting circFSCN1, a novel identified target, may be conducive in impeding BC progression and providing survival benefits for patients with BC.

CircPPAP2B controls metastasis of clear cell renal cell carcinoma via HNRNPC-dependent alternative splicing and targeting the miR-182-5p/CYP1B1 axis

BACKGROUND

Renal cell carcinoma (RCC) is one of the most common malignant tumor worldwide. Metastasis is a leading case of cancer-related deaths of RCC. Circular RNAs (circRNAs), a class of noncoding RNAs, have emerged as important regulators in cancer metastasis. However, the functional effects and regulatory mechanisms of circRNAs on RCC metastasis remain largely unknown.

METHODS

High-throughput RNA sequencing techniques were performed to analyze the expression profiles of circRNAs and mRNAs in highly and poorly invasive clear cell renal cell carcinoma (ccRCC) cell lines. Functional experiments were performed to unveil the regulatory role of circPPAP2B in the proliferation and metastatic capabilities of ccRCC cells. RNA pulldown, Mass spectrometry analysis, RNA methylation immunoprecipitation (MeRIP), RNA immunoprecipitation (RIP), co-immunoprecipitation (CoIP), next-generation RNA-sequencing and double luciferase experiments were employed to clarify the molecular mechanisms by which circPPAP2B promotes ccRCC metastasis.

RESULTS

In this study, we describe a newly identified circular RNA called circPPAP2B, which is overexpressed in highly invasive ccRCC cells, as determined through advanced high-throughput RNA sequencing techniques. Furthermore, we observed elevated circPPAP2B in ccRCC tissues, particularly in metastatic ccRCC tissues, and found it to be associated with poor prognosis. Functional experiments unveiled that circPPAP2B actively stimulates the proliferation and metastatic capabilities of ccRCC cells. Mechanistically, circPPAP2B interacts with HNRNPC in a m6A-dependent manner to facilitate HNRNPC nuclear translocation. Subcellular relocalization was dependent upon nondegradable ubiquitination of HNRNPC and stabilization of an HNRNPC/Vimentin/Importin α7 ternary complex. Moreover, we found that circPPAP2B modulates the interaction between HNRNPC and splicing factors, PTBP1 and HNPNPK, and regulates pre-mRNA alternative splicing. Finally, our studies demonstrate that circPPAP2B functions as a miRNA sponge to directly bind to miR-182-5p and increase CYP1B1 expression in ccRCC.

CONCLUSIONS

Collectively, our study provides comprehensive evidence that circPPAP2B promotes proliferation and metastasis of ccRCC via HNRNPC-dependent alternative splicing and miR-182-5p/CYP1B1 axis and highlights circPPAP2B as a potential therapeutic target for ccRCC intervention.

Molecular mechanism of microRNAs, long noncoding RNAs, and circular RNAs regulating lymphatic metastasis of bladder cancer

Bladder cancer (BC), a malignancy originating in the epithelial tissue in the inner wall of the bladder, is a common urological cancer type. BC spreads through 3 main pathways: direct infiltration, lymphatic metastasis, and hematogenous metastasis. Lymphatic metastasis is considered a poor prognostic factor for BC and is often associated with lower survival rates. The treatment of BC after lymphatic metastasis is complex and challenging. A deeper understanding of the molecular mechanisms underlying lymphatic metastasis of BC may yield potential targets for its treatment. Here, we summarize the current knowledge on epigenetic factors-including miRNAs, lncRNAs, and circRNAs-associated with lymphatic metastasis in BC. These factors are strongly associated with lymphangiogenesis, cancer cell proliferation and migration, and epithelial-mesenchymal transition processes, providing new insights to develop newer BC treatment strategies.

Circular RNAs: Emerging Modulators in the Pathophysiology of Polycystic Ovary Syndrome and their Clinical Implications

Polycystic ovary syndrome (PCOS) is a prevalent endocrine/metabolic disorder in women of reproductive age. PCOS is characterized by hyperandrogenism, polycystic ovary morphology, and ovulatory dysfunction/anovulation. It involves multiple effects in patients, including granulosa/theca cell hyperplasia, menstrual disturbances, infertility, acne, obesity, insulin resistance, and cardiovascular disorders. Biochemical analyses and the results of RNA sequencing studies in recent years have shown a type of non-coding RNAs as a splicing product known as circular RNAs (circRNAs). Several biological functions have been identified in relation to circRNAs, including a role in miRNA sponge, protein sequestration, increased parental gene expression, and translation leading to polypeptides. These circular molecules are more plentiful and specialized than other types of RNAs. For this reason, they are referred to as potential biomarkers in different diseases. Evidence suggests that circRNAs may have regulatory potentials through different signaling pathways, such as the miRNA network. Probably most experts in the field of obstetricians are not aware of circRNAs as a useful biomarker. Therefore, this review focused on the researches that have been done on the involvement of circRNAs in PCOS and summarized recent supportive evidence, and evaluated the circRNA association and mechanisms involved in PCOS.

Identification of Differential Circular RNA Expression Profiles and Functional Networks in Human Macrophages Induced by Virulent and Avirulent Mycobacterium tuberculosis Strains

Circular RNAs (circRNAs) are noncoding RNAs with diverse functions. However, most Mycobacterium tuberculosis (M.tb)-related circRNAs remain undiscovered. In this study, we infected THP-1 cells with virulent and avirulent M.tb strains and then sequenced the cellular circRNAs. Bioinformatic analysis predicted 58,009 circRNAs in all the cells. In total, 2035 differentially expressed circRNAs were identified between the M.tb-infected and uninfected THP-1 cells and 1258 circRNAs were identified in the virulent and avirulent M.tb strains. Further, the top 10 circRNAs were confirmed by Sanger sequencing, among which four circRNAs, namely circSOD2, circCHSY1, circTNFRSF21, and circDHTKD1, which were highly differentially expressed in infected cells compared with those in uninfected cells, were further confirmed by ring formation, specific primers, and RNase R digestion. Next, circRNA-miRNA-mRNA subnetworks were constructed, such as circDHTKD1/miR-660-3p/IL-12B axis. Some of the individual downstream genes, such as miR-660-3p and IL-12B, were previously reported to be associated with cellular defense against pathological processes induced by M.tb infection. Because macrophages are important immune cells and the major host cells of M.tb, these findings provide novel ideas for exploring the M.tb pathogenesis and host defense by focusing on the regulation of circRNAs during M.tb infection.

NR1H4-mediated circRHOBTB3 modulates the proliferation, metastasis, and Warburg effects of cervical cancer through interacting with IGF2BP3

Globally, cervical cancer (CC) ranks as the fourth most common cancer and the most lethal malignancy among females of reproductive age. The incidence of CC is increasing in low-income countries, with unsatisfactory outcomes and long-term survival for CC patients. Circular RNAs (CircRNAs) are promising therapeutics that target multiple cancers. In this study, we investigated the tumorigenic role of circRHOBTB3 in CC, showing that circRHOBTB3 is highly expressed in CC cells and circRHOBTB3 knockdown also repressed CC proliferation, migration, invasion, and the Warburg effects. CircRHOBTB3 interacted with the RNA-binding protein, IGF2BP3, to stabilize its expression in CC cells and is putatively transcriptionally regulated by NR1H4. In conclusion, this novel NR1H4/circRHOBTB3/IGF2BP3 axis may provide new insights into CC pathogenesis.

A circRNA-based ceRNA network shows its diagnostic value in non-small-cell lung cancer

BACKGROUND

Numerous studies have reported the vital roles of circular RNA (circRNA)-based competitive endogenous RNA (ceRNA) regulatory networks in cancers. Here, we established a non-small-cell lung cancer (NSCLC)-related circRNA-miRNA-mRNA axis and estimated its diagnostic value in NSCLC.

METHODS

The circ_0061235-miR-3180-5p-PPM1L axis was constructed by small RNA deep sequencing, bioinformatics databases, and preliminary testing. The serum levels of the selected circ_0061235, miR-3180-5p, and PPM1L were quantified using quantitative polymerase chain reaction. Receiver operating characteristic analyses were conducted to evaluate the diagnostic power.

RESULTS

The levels of circ_0061235, miR-3180-5p, and PPM1L showed close correlations according to the ceRNA regulation rule. They were significantly dysregulated in NSCLC and showed the diagnostic ability to discriminate between healthy and NSCLC, and remarkably, between benign lung tumors and NSCLC. Additionally, the down-regulated levels of hsa_circ_0061235, the up-regulated levels of miR-3180-5p, and the decreased levels of PPM1L were correlated to more aggressive features of NSCLC, such as lymph node metastasis, distant metastasis, and higher stages. Intriguingly, compared to the single circ_0061235, miR-3180-5p, PPM1L, and traditional tumor markers, the diverse combinations of circ_0061235, miR-3180-5p, and PPM1L showed much higher sensitivity and specificity to differentiate greater or lesser severity of NSCLC. GO annotation and KEGG pathway analyses revealed the underlying role of the circ_0061235-miR-3180-5p-PPM1L axis in NSCLC.

CONCLUSIONS

We established a specific circRNA-miRNA-mRNA network with higher sensitivity and specificity to diagnose NSCLC, particularly more aggressive NSCLC, providing a new strategy for further developing tumor biomarkers.

Urine biomarkers in bladder cancer - current status and future perspectives

Urine markers to detect bladder cancer have been the subject of research for decades. The idea that urine - being in continuous contact with tumour tissue - should provide a vector of tumour information remains an attractive concept. Research on this topic has resulted in a complex landscape of many different urine markers with varying degrees of clinical validation. These markers range from cell-based assays to proteins, transcriptomic markers and genomic signatures, with a clear trend towards multiplex assays. Unfortunately, the number of different urine markers and the efforts in research and development of clinical grade assays are not reflected in the use of these markers in clinical practice, which is currently limited. Numerous prospective trials are in progress with the aim of increasing the quality of evidence about urinary biomarkers in bladder cancer to achieve guideline implementation. The current research landscape suggests a division of testing approaches. Some efforts are directed towards addressing the limitations of current assays to improve the performance of urine markers for a straightforward detection of bladder cancer. Additionally, comprehensive genetic analyses are emerging based on advances in next-generation sequencing and are expected to substantially affect the potential application of urine markers in bladder cancer.

LncRNA LINC00592 mediates the promoter methylation of WIF1 to promote the development of bladder cancer

Epigenetic alteration is a key feature that contributes to the progression of bladder cancer (BC) and long non-coding RNAs serve crucial role in the epigenetic modulation. This study was designed to explore the epigenetic regulation of LINC00592 in BC. LINC00592 expression in BC was examined. Then, LINC00592 was silenced in BC cell followed by cell behavior analyses using CCK-8, transwell, western blot, or flow cytometry. Potential downstream target of LINC00592 was explored using RNA pull-down assay and methylation of WIF1 was determined using methylated-specific PCR. In addition, WIF1 or/and LINC00592 were silenced in BC cells followed by cell behavior analyses to explore the regulation between them. Upregulation of LINC00592 was significantly detected in BC tissues and cells. In BC cells silencing LINC00592 suppressed the proliferation, migration, and epithelial-mesenchymal transitions (EMT), but enhanced apoptosis. Moreover, LINC00592 recruited DNMT1, DNMT3A, and DNMT3B to enhance WIF1 promoter methylation. In addition, WIF1 overexpression suppressed the proliferation, migration, as well as EMT, but enhanced apoptosis. Silencing WIF1 significantly attenuated the role of silencing LINC00592 in suppressing the proliferative, migratory, and EMT ability of BC cells, and increasing the apoptosis. LINC00592 promoted the growth and metastasis of BC via enhancing the promoter methylation of WIF1 and decreasing WIF1 transcription.

EIF4A3-regulated hsa_circ_0001445 can inhibit the progression of laryngeal squamous cell carcinoma via hsa-miR-432-5p-dependent up-regulation of RGMA expression

Laryngeal squamous cell carcinoma (LSCC) is a common malignant tumor in the head and neck, the 5-year relative survival rate of patients diagnosed with laryngeal cancer was estimated to be 61% from 2012 to 2018. An increasing number of studies have shown that circular RNAs (circRNAs) play a key role in the occurrence and development of cancer and may function as cancer biomarkers and new therapeutic targets. At present, the research on the relationship between circRNAs and LSCC is still in its infancy and needs further exploration. In this study, we found a circRNA (hsa_circ_0001445) associated with LSCC based on bioinformatics analysis. Quantitative real-time polymerase chain reaction (qRT-PCR) assay indicated that the expression of hsa_circ_0001445 was down-regulated in LSCC tissues and cell lines. Notably, the expression of hsa_circ_0001445 was negatively correlated with aggressive clinicopathological features and poor prognosis. Then, functional experiments found that overexpression of hsa_circ_0001445 inhibited the proliferation, migration and invasion of LSCC cells and tumor growth in vivo. Mechanistically, RNA immunoprecipitation (RIP), biotin-labeled probe pull-down, luciferase reporter assay and western blot experiments were employed and found that EIF4A3 reduced the expression of hsa_circ_0001445, and the direct binding of hsa_circ_0001445 to hsa-miR-432-5p attenuated the inhibitory effect of hsa-miR-432-5p on RGMA. In summary, our research suggests that hsa_circ_0001445 may be used as a potential prognostic biomarker and therapeutic target for LSCC.

Hsa_circ_0003098 promotes bladder cancer progression via miR-377-5p/ACAT2 axis

Accumulating evidence has proven that circRNAs play vital roles in tumor progression. Nevertheless, the mechanisms underlying circRNAs in bladder cancer (BCa) remain largely unknown. The purpose of this study was to identify the role and investigate the potential molecular mechanisms of hsa_circ_0003098 in BCa. We confirmed that hsa_circ_0003098 expression was significantly upregulated in BCa tissues, of which expression was remarkably associated with poor prognosis. Functionally, overexpression of hsa_circ_0003098 promoted BCa cell proliferation, migration, and invasion in vitro as well as tumor growth in vivo. Mechanistically, hsa_circ_0003098 promoted upregulation of ACAT2 expression and induced cholesteryl ester accumulation via acting as a sponge for miR-377-5p. Thus, hsa_circ_0003098 plays an oncogenic role in BCa and may serve as a potential biomarker and therapeutic target for BCa.

Construction of a cuproptosis-associated lncRNA prognostic signature for bladder cancer and experimental validation of cuproptosis-related lncRNA UBE2Q1-AS1

Introduction

Bladder cancer (BLCA) is the ninth most common malignancy worldwide and the fourth most common cancer in men. Copper levels are significantly altered in patients with thyroid, breast, lung, cervical, ovarian, pancreatic, oral, gastric, bladder, and prostate cancers. Outcomes can be predicted by constructing signatures using lncRNA-related genes associated with outcomes.

Methods

We identified lncRNAs related to outcomes, those differentially expressed in bladder cancer, and cuproptosis-related lncRNAs from TCGA. We identified the intersection to obtain 12 genes and established a prognostic risk signature consisting of eight genes using LASSO-penalized multivariate Cox analysis. We constructed a training set, performed survival analysis on the high-and low-risk groups, and performed validation in the test and full sets. There existed a substantial contrast in the likelihood of survival among the cohorts of high and low risk. An in-depth analysis of the gene mutations associated with tumors was conducted to evaluate the risk of developing cancer. We also performed gene analysis on neoadjuvant chemotherapy. We conducted experimental validation on the key gene UBE2Q1-AS1 in our prognostic signature.

Results

The risk signature we constructed shows significant differences between the high-risk group and the low-risk group. Univariate survival analysis of the eight genes in our signature showed that each gene distinguished between high- and low-risk groups. Sub-group analysis revealed that our risk score differed significantly in tumor stage, age, and gender. The analysis results of the tumor mutation burden (TMB) showed a significant difference in the TMB between the low- and high-risk groups, which had a direct impact on the outcomes. These findings highlight the importance of TMB as a potential prognostic marker in cancer detection and prevention. We analyzed the immune microenvironment and found significant differences in immune function, validation responses, immunotherapy-related positive markers, and critical steps in the tumor immunity cycle between the high- and low-risk groups. We found that the effect of anti-CTLA4 and PD-1 was higher in the high-risk group than in the low-risk group.Gene analysis of neoadjuvant chemotherapy revealed that the treatment effect in the high-risk group was better than in the low-risk group. The key gene UBE2Q1-AS1 in our prognostic signature can significantly influence the cell viability, migration, and proliferation of cancer cells.

Discussion

We established a signature consisting of eight genes constructed from cuproptosis-related lncRNAs that have potential clinical applications for outcomes prediction, diagnosis, and treatment.

A novel CD8+ T cell-related gene signature for predicting the prognosis and immunotherapy efficacy in bladder cancer

OBJECTIVE

To identify CD8+ T cell-related molecular clusters and establish a novel gene signature for predicting the prognosis and efficacy of immunotherapy in bladder cancer (BCa).

METHODS

Transcriptome and clinical data of BCa samples were obtained from the Cancer Genome Atlas (TCGA) and GEO databases. The CD8+ T cell-related genes were screened through the CIBERSORT algorithm and correlation analysis. Consensus clustering analysis was utilized to identified CD8+ T cell-related molecular clusters. A novel CD8+ T cell-related prognostic model was developed using univariate Cox regression analysis and Lasso regression analysis. Internal and external validations were performed and the validity of the model was validated in a real-world cohort. Finally, preliminary experimental verifications were carried out to verify the biological functions of SH2D2A in bladder cancer.

RESULTS

A total of 52 CD8+ T cell-related prognostic genes were screened and two molecular clusters with notably diverse immune cell infiltration, prognosis and clinical features were developed. Then, a novel CD8+ T cell-related prognostic model was constructed. The patients with high-risk scores exhibited a significantly worse overall survival in training, test, whole TCGA and validating cohort. The AUC was 0.766, 0.725, 0.739 and 0.658 in the four cohorts sequentially. Subgroup analysis suggested that the novel prognostic model has a robust clinical application for selecting high-risk patients. Finally, we confirmed that patients in the low-risk group might benefit more from immunotherapy or chemotherapy, and validated the prognostic model in a real-world immunotherapy cohort. Preliminary experiment showed that SH2D2A was capable of attenuating proliferation, migration and invasion of BCa cells.

CONCLUSIONS

CD8+ T cell-related molecular clusters were successfully identified. Besides, a novel CD8+ T cell-related prognostic model with an excellent predictive performance in predicting survival rates and immunotherapy efficacy of BCa was developed.

Circular RNAs in hepatocellular carcinoma: biogenesis, function, and pathology

Hepatocellular carcinoma (HCC) is one of the most common causes of cancer-related death worldwide. Both genetic and environmental factors through a multitude of underlying molecular mechanisms participate in the pathogenesis of HCC. Recently, numerous studies have shown that circular RNAs (circRNAs), an emerging class of non-coding RNAs characterized by the presence of covalent bonds linking 3' and 5' ends, play an important role in the initiation and progression of cancers, including HCC. In this review, we outline the current status of the field of circRNAs, with an emphasis on the functions and mechanisms of circRNAs in HCC and its microenvironment. We also summarize and discuss recent advances of circRNAs as biomarkers and therapeutic targets. These efforts are anticipated to throw new insights into future perspectives about circRNAs in basic, translational and clinical research, eventually advancing the diagnosis, prevention and treatment of HCC.

CircGNB1 facilitates the malignant phenotype of GSCs by regulating miR-515-5p/miR-582-3p-XPR1 axis

Glioma is the most common and aggressive primary malignant brain tumor. Circular RNAs (circRNAs) and RNA-binding proteins (RBPs) have been verified to mediate diverse biological behaviors in various human cancers. Therefore, the aim of this study was to explore a novel circRNA termed circGNB1 and elucidate relative molecular mechanism in functional phenotypes, which might be a potential prognostic biomarker and therapeutic approach for glioma. CircGNB1 was upregulated in glioma and closely associated with the low poor prognosis. Functional assays demonstrated that circGNB1 overexpression promoted glioma stem cells (GSCs) viability proliferation, invasion, and neurosphere formation. Mechanistically, circGNB1 upregulated the expression of oncogene XPR1 via sponging miR-515-5p and miR-582-3p. The following experiments proved XPR1 could promote the malignant phenotype of GSCs via upregulating IL6 expression and activating JAK2/STAT3 signaling. Moreover, the RNA binding protein IGF2BP3 could bind to and maintain the stability of circGNB1, thus promoting the effects of circGNB1 on GSCs. Our study reveals that circGNB1 plays a crucial role in promoting tumorigenesis and malignant progression in glioma, which provides a promising cancer biomarker.

An Overview of Angiogenesis in Bladder Cancer

PURPOSE OF THE REVIEW

Angiogenesis plays a key role in bladder cancer (BC) pathogenesis. In the last two decades, an increasing number of publications depicting a multitude of novel angiogenic molecules and pathways have emerged. The growing complexity necessitates an evaluation of the breadth of current knowledge to highlight key findings and guide future research.

RECENT FINDINGS

Angiogenesis is a dynamic biologic process that is inherently difficult to assess. Clinical assessment of angiogenesis in BCs is advancing with the integration of image analysis systems and dynamic contrast-enhanced and magnetic resonance imaging (DCE-MRI). Tumour-associated macrophages (TAMs) significantly influence the angiogenic process, and further research is needed to assess their potential as therapeutic targets. A rapidly growing list of non-coding RNAs affect angiogenesis in BCs, partly through modulation of vascular endothelial growth factor (VEGF) activity. Vascular mimicry (VM) has been repeatedly associated with increased tumour aggressiveness in BCs. Standardised assays are needed for appropriate identification and quantification of VM channels. This article demonstrates the dynamic and complex nature of the angiogenic process and asserts the need for further studies to deepen our understanding.

Off the fog to find the optimal choice: Research advances in biomarkers for early diagnosis and recurrence monitoring of bladder cancer

Bladder cancer (BC) has high morbidity and mortality rates owing to challenges in clinical diagnosis and treatment. Advanced BC is prone to recurrence after surgery, necessitating early diagnosis and recurrence monitoring to improve the prognosis of patients. Traditional detection methods for BC include cystoscopy, cytology, and imaging; however, these methods have drawbacks such as invasiveness, lack of sensitivity, and high costs. Existing reviews on BC focus on treatment and management and lack a comprehensive assessment of biomarkers. Our article reviews various biomarkers for the early diagnosis and recurrence monitoring of BC and outlines the existing challenges associated with their application and possible solutions. Furthermore, this study highlights the potential application of urine biomarkers as a non-invasive, inexpensive adjunctive test for screening high-risk populations or evaluating patients with suspected BC symptoms, thereby alleviating the discomfort and financial burden associated with cystoscopy and improving patient survival.

CircRNAs in colorectal cancer: potential biomarkers and therapeutic targets

Globally, colorectal cancer (CRC) is the third most prevalent cancer and the second leading cause of cancer-related deaths. Circular RNAs (circRNAs) are single-stranded RNA with covalently closed-loop structures and are highly stable, conserved, and abundantly expressed in various organs and tissues. Recent research found abnormal circRNA expression in CRC patients' blood/serum, cells, CRC tissues, and exosomes. Furthermore, mounting data demonstrated that circRNAs are crucial to the development of CRC. CircRNAs have been shown to exert biological functions by acting as microRNA sponges, RNA-binding protein sponges, regulators of gene splicing and transcription, and protein/peptide translators. These characteristics make circRNAs potential markers for CRC diagnosis and prognosis, potential therapeutic targets, and circRNA-based therapies. However, further studies are still necessary to improve the understanding of the roles and biological mechanisms of circRNAs in the development of CRC. In this review, up-to-date research on the role of circRNAs in CRC was examined, focusing on their potential application in CRC diagnosis and targeted therapy, which would advance the knowledge of the functions of circRNAs in the development and progression of CRC.

The short inverted repeats-induced circEXOC6B inhibits prostate cancer metastasis by enhancing the binding of RBMS1 and HuR

Circular RNAs (circRNAs) are a novel class of endogenous RNAs with a covalently closed loop structure. Many circRNAs have been found to participate in cancer progression. However, the detailed generation process, functions, and related mechanisms of circRNAs in prostate cancer (PCa) remain largely unknown. In the present study, we identified circEXOC6B, a novel suppressor in the metastasis of PCa. Functionally, circEXOC6B, originating from the exocyst complex component 6B (EXOC6B) gene, inhibited migration and invasion of PCa in vitro and in vivo. Mechanistically, by acting as a protein scaffold, circEXOC6B enhanced the binding of human RNA binding motif single strand interacting protein 1 (RBMS1) and human antigen R (HuR) and further increased A-kinase anchoring protein 12 (AKAP12) expression to inhibit PCa metastasis. Unlike previous studies, we found that one pair of short inverted repeats in flanking introns at least partly promoted the circularization of circEXOC6B. Our study presents a novel mechanism for the inhibitory role of circEXOC6B in PCa metastasis and provides new insight into the molecular process of circRNA generation.

Single-cell RNA sequencing reveals sexual diversity in the human bladder and its prospective impacts on bladder cancer and urinary tract infection

BACKGROUND

Some bladder-related diseases, such as bladder urinary tract infection (UTI) and bladder cancer (BCa), have significant six differences in incidence and prognosis. However, the molecular mechanisms underlying these sex differences are still not fully understood. Understanding the sex-biased differences in gene expression in normal bladder cells can help resolve these problems.

METHODS

We first collected published single-cell RNA sequencing (scRNA-seq) data of normal human bladders from females and males to map the bladder transcriptomic landscape. Then, Gene Ontology (GO) analysis and gene set enrichment analysis (GSEA) were used to determine the significant pathways that changed in the specific cell populations. The Monocle2 package was performed to reconstruct the differentiation trajectories of fibroblasts. In addition, the scMetabolism package was used to analyze the metabolic activity at the single-cell level, and the SCENIC package was used to analyze the regulatory network.

RESULTS

In total, 27,437 cells passed stringent quality control, and eight main cell types in human bladder were identified according to classical markers. Sex-based differential gene expression profiles were mainly observed in human bladder urothelial cells, fibroblasts, B cells, and T cells. We found that urothelial cells in males demonstrated a higher growth rate. Moreover, female fibroblasts produced more extracellular matrix, including seven collagen genes that may mediate BCa progression. Furthermore, the results showed that B cells in female bladders exhibited more B-cell activated signals and a higher expression of immunoglobulin genes. We also found that T cells in female bladders exhibited more T-cell activated signals. These different biological functions and properties of these cell populations may correlate with sex differences in UTI and BCa, and result in different disease processes and outcomes.

CONCLUSIONS

Our study provides reasonable insights for further studies of sex-based physiological and pathological disparities in the human bladder, which will contribute to the understanding of epidemiological differences in UTI and BCa.

CircHIPK3 negatively regulates autophagy by blocking VCP binding to the Beclin 1 complex in bladder cancer

Circular RNA HIPK3 (circHIPK3) mediates the progression of multiple cancers, including bladder cancer, by regulating cell migration, autophagy and epithelial mesenchymal transition. However, the mechanism by which circHIPK3 regulates autophagy in bladder cancer cells remains unclear. Autophagy is a common self-protection mechanism in eukaryotic cells and is essential for cell survival and death regulation. However, it is unclear whether circHIPK3 affects the level of autophagy in bladder cancer through binding proteins, and the potential regulatory mechanism is unknown. Here, we found that circHIPK3 levels were significantly lower and autophagy-related proteins were significantly upregulated in bladder cancer cells and tissues compared to normal controls. CircHIPK3 downregulation promoted bladder cancer cell proliferation, while circHIPK3 overexpression inhibited proliferation. CircHIPK3 overexpression significantly suppressed autophagy in bladder cancer cells. Overexpression of circHIPK3 did not affect VCP protein expression but inhibited the VCP/Beclin 1 interaction. VCP also stabilized Beclin 1 and promoted autophagy in bladder cancer cells by downregulating ataxin-3. Thus, circHIPK3 may play an important role in bladder cancer by inhibiting VCP-mediated autophagy.

[Read-through circular RNA rt-circ-HS promotes hypoxia inducible factor 1α expression and renal carcinoma cell proliferation, migration and invasiveness]

OBJECTIVE

To identify and characterize read-through RNAs and read-through circular RNAs (rt-circ-HS) derived from transcriptional read-through hypoxia inducible factor 1α (HIF1α) and small nuclear RNA activating complex polypeptide 1 (SNAPC1) the two adjacent genes located on chromosome 14q23, in renal carcinoma cells and renal carcinoma tissues, and to study the effects of rt-circ-HS on biological behavior of renal carcinoma cells and on regulation of HIF1α.

METHODS

Reverse transcription-polymerase chain reaction (RT-PCR) and Sanger sequencing were used to examine expression of read-through RNAs HIF1α-SNAPC1 and rt-circ-HS in different tumor cells. Tissue microarrays of 437 different types of renal cell carcinoma (RCC) were constructed, and chromogenic in situ hybridization (ISH) was used to investigate expression of rt-circ-HS in different RCC types. Small interference RNA (siRNA) and artificial overexpression plasmids were designed to examine the effects of rt-circ-HS on 786-O and A498 renal carcinoma cell proliferation, migration and invasiveness by cell counting kit 8 (CCK8), EdU incorporation and Transwell cell migration and invasion assays. RT-PCR and Western blot were used to exa-mine expression of HIF1α and SNAPC1 RNA and proteins after interference of rt-circ-HS with siRNA, respectively. The binding of rt-circ-HS with microRNA 539 (miR-539), and miR-539 with HIF1α 3' untranslated region (3' UTR), and the effects of these interactions were investigated by dual luciferase reporter gene assays.

RESULTS

We discovered a novel 1 144 nt rt-circ-HS, which was derived from read-through RNA HIF1α-SNAPC1 and consisted of HIF1α exon 2-6 and SNAPC1 exon 2-4. Expression of rt-circ-HS was significantly upregulated in 786-O renal carcinoma cells. ISH showed that the overall positive expression rate of rt-circ-HS in RCC tissue samples was 67.5% (295/437), and the expression was different in different types of RCCs. Mechanistically, rt-circ-HS promoted renal carcinoma cell proliferation, migration and invasiveness by functioning as a competitive endogenous inhibitor of miR-539, which we found to be a potent post-transcriptional suppressor of HIF1α, thus promoting expression of HIF1α.

CONCLUSION

The novel rt-circ-HS is highly expressed in different types of RCCs and acts as a competitive endogenous inhibitor of miR-539 to promote expression of its parental gene HIF1α and thus the proliferation, migration and invasion of renal cancer cells.

CircHGS enhances the progression of bladder cancer by regulating the miR-513a-5p/VEGFC axis and activating the AKT/mTOR signaling pathway

Bladder cancer (BCa) is a malignant tumor that occurs in the bladder mucosa with high mortality. Circular RNAs (circRNAs), as newly discovered noncoding RNAs, are associated with the occurrence and development of BCa. However, the effects of circRNAs in BCa have not been fully elucidated. Through the GEO (Gene Expression Omnibus) database, an abnormally expressed circular RNA, circHGS (hsa_circ_0004721), was first identified in BCa. qRT - PCR was performed to measure the expression of circHGS in BCa tissues and cells. The intracellular localization of circHGS was detected by nucleocytoplasmic separation experiment and fluorescence in situ hybridization assay. In vitro experiments were conducted to detect the effects of circHGS on cell cycle, proliferation, migration and invasion. The correlations between miR-513a-5p and circHGS or VEGFC were confirmed by dual-luciferase reporter assay, qRT - PCR and western blot. The role of circHGS in vivo was verified by xenograft tumor mice model. In this study, we clarified the roles and potential mechanism of circHGS in BCa. CircHGS, originating from the HGS gene, is upregulated in BCa tissues compared to normal tissues. Moreover, the expression of circHGS in BCa was positively associated with tumor grade and pathological T stage. Functionally, silencing of circHGS apparently suppressed cell cycle, proliferation, migration and invasion, but circHGS overexpression showed the opposite result. In vivo experiments also suggested that knockdown of circHGS suppressed tumor growth. Mechanistically, circHGS functions as a sponge of miR-513a-5p to elevate VEGFC expression and activate the AKT/mTOR signaling pathway, ultimately promoting BCa progression. Our findings indicated that circHGS promotes BCa progression via the miR-513a-5p/VEGFC/AKT/mTOR pathway and can be a promising therapeutic target of BCa.