Low Expression of hsa_circ_0018069 in Human Bladder Cancer and Its Clinical Significance

Circular RNA CCT3 is a unique molecular marker in bladder cancer

This study surveyed circular RNA CCT3 in bladder cancer (BCa). We recruited 85 BCa patients and 40 normal controls (Normal) and collected clinical specimens for analysis. circRNA CCT3 expression was analyzed by RT-qPCR, diagnostic accuracy was calculated by ROC curves, and survival outcomes were evaluated by survival curves. CircRNA CCT3 was overexpressed or knocked down in cells, thereafter to observe the changes in cell malignant phenotypes. The downstream molecules of circRNA CCT3 were detected. Our data suggest that circRNA CCT3 was upregulated in human BCa and was associated with poor survival outcomes of BCa patients. In cell experiments, overexpressing circRNA CCT3 promoted BCa cell malignancy, whereas silencing circRNA CCT3 did the opposite. In addition, circRNA CCT3 modulated PP2A expression by miR-135a-5p. This study demonstrates that circRNA CCT3 is a diagnostic and prognostic biomarker in BCa patients and is a tumor promoter in BCa.

[SLC12A8 promotes proliferation, invasiveness, migration and epithelial-mesenchymal transition of bladder cancer cells by activating JAK/STAT singaling]

OBJECTIVE

To investigate the role of solute carrier family 12 member A8 (SLC12A8) in regulation of biological behaviors of bladder cancer and the mechanism mediating its effect.

METHODS

The TCGA database was used to analyze SLC12A8 expression in bladder cancer and is correlation with prognosis and clinicopathological characteristics of the patients. In different bladder cancer cell lines, the effects of transient transfection with SLC12A8 siRNA on cell proliferation, invasion and migration ability were examined using CCK-8 assay, Transwell assay and scratch experiment. Gene set enrichment analysis (GSEA) was carried out to analyze pathway enrichment. The correlation of SLC12A8 with the expressions of epithelial-mesenchymal transition (EMT) markers was analyzed using Western blotting. The effect of colivelin on biological behaviors of the cells with SLC12A8 knockdown was assessed using CCK-8 and Transwell assays.

RESULTS

SLC12A8 was highly expressed in bladder cancer (P<0.05) and associated with a poor prognosis and advanced pathological stages of the patients (P<0.05), and could serve as an independent prognostic factor. The bladder cancer cell lines with SLC12A8 knockdown showed significantly attenuated proliferation, invasion and migration capacities (P<0.05). GSEA identified significant gene enrichment in the JAK/STAT signaling pathway (P=0.008). Correlation analysis showed that SLC12A8 expression was negatively correlated with E- cadherin expression (r=-0.167, P<0.001) but positively with N-cadherin (r=0.306, P<0.001) and vimentin (r=0.358, P<0.001) expressions. The bladder cancer cells with SLC12A8 knockdown showed significantly decreased expressions of p-Jak2, p-Stat3, N-cadherin and vimentin proteins with an increased expression of E-cadherin. Treatment with colivelin effectively enhanced proliferation, invasion and migration capacities of the bladder cancer cells with SLC12A8 knockdown (P<0.05).

CONCLUSION

SLC12A8 promotes bladder cancer progression by activating the JAK/STAT signaling pathway and its high expression is closely associated with a poor prognosis of the patients.

The potential role and mechanism of circRNA/miRNA axis in cholesterol synthesis

Cholesterol levels are an initiating risk factor for atherosclerosis. Many genes play a central role in cholesterol synthesis, including HMGCR, SQLE, HMGCS1, FDFT1, LSS, MVK, PMK, MVD, FDPS, CYP51, TM7SF2, LBR, MSMO1, NSDHL, HSD17B7, DHCR24, EBP, SC5D, DHCR7, IDI1/2. Especially, HMGCR, SQLE, FDFT1, LSS, FDPS, CYP51, and EBP are promising therapeutic targets for drug development due to many drugs have been approved and entered into clinical research by targeting these genes. However, new targets and drugs still need to be discovered. Interestingly, many small nucleic acid drugs and vaccines were approved for the market, including Inclisiran, Patisiran, Inotersen, Givosiran, Lumasiran, Nusinersen, Volanesorsen, Eteplirsen, Golodirsen, Viltolarsen, Casimersen, Elasomeran, Tozinameran. However, these agents are all linear RNA agents. Circular RNAs (circRNAs) may have longer half-lives, higher stability, lower immunogenicity, lower production costs, and higher delivery efficiency than these agents due to their covalently closed structures. CircRNA agents are developed by several companies, including Orna Therapeutics, Laronde, and CirCode, Therorna. Many studies have shown that circRNAs regulate cholesterol synthesis by regulating HMGCR, SQLE, HMGCS1, ACS, YWHAG, PTEN, DHCR24, SREBP-2, and PMK expression. MiRNAs are essential for circRNA-mediated cholesterol biosynthesis. Notable, the phase II trial for inhibiting miR-122 with nucleic acid drugs has been completed. Suppressing HMGCR, SQLE, and miR-122 with circRNA_ABCA1, circ-PRKCH, circEZH2, circRNA-SCAP, and circFOXO3 are the promising therapeutic target for drug development, specifically the circFOXO3. This review focuses on the role and mechanism of the circRNA/miRNA axis in cholesterol synthesis in the hope of providing knowledge to identify new targets.

The feedback loop of METTL14 and USP38 regulates cell migration, invasion and EMT as well as metastasis in bladder cancer

Background

Bladder cancer (BCa) is one of the most prevalent malignancies globally. Previous study has reported the inhibitory effect of methyltransferase-like 14 (METTL14) on BCa tumorigenesis, but its role in the cell migration, invasion and epithelial–mesenchymal transition (EMT) in BCa remains unknown.

Materials and methods

Quantitative real-time PCR (RT-qPCR) and western blot were applied to measure RNA and protein expression respectively. Cell migration, invasion and EMT were evaluated by wound healing, Transwell, and immunofluorescence (IF) assays as well as western blot of EMT-related proteins. In vivo experiments were performed to analyze metastasis of BCa. Mechanism investigation was also conducted to study METTL14-mediated regulation of BCa progression.

Results

METTL14 overexpression prohibits BCa cell migration, invasion in vitro and tumor metastasis in vivo. METTL14 stabilizes USP38 mRNA by inducing N6-methyladenosine (m6A) modification and enhances USP38 mRNA stability in YTHDF2-dependent manner. METTL14 represses BCa cell migration, invasion and EMT via USP38. Additionally, miR-3165 inhibits METTL14 expression to promote BCa progression.

Conclusions

Our study demonstrated that METTL14 suppresses BCa progression and forms a feedback loop with USP38. In addition, miR-3165 down-regulates METTL14 expression to promote BCa progression. The findings may provide novel insight into the underlying mechanism of METTL14 in BCa progression.

Bladder cancer (BCa) is a common type of cancer that begins in the cells of the bladder and poses a significant threat to human health worldwide. In order to improve the diagnosis and treatment of BCa, molecular mechanisms associated with BCa tumorigenesis and tumor progression needs to be clarified. Currently, long non-coding RNAs (lncRNAs) have been suggested to act as regulators of cancer progression. Here, we identified lncRNA methyltransferase-like 14 (METTL14) as a tumor-suppressor gene in BCa, acting to inhibit cell migration, invasion and epithelial–mesenchymal transition (EMT) as well as tumor metastasis. We also found that METTL14 forms a feedback loop with ubiquitin specific peptidase 38 (USP38) in BCa. In addition, microRNA-3165 (miR-3165) was verified as an upstream regulator of METTL14 and was elucidated to downregulate METTL14 expression, contributing to the malignancy of BCa. Given that the therapeutic potential of some miRNAs have been identified in a number of diseases, targeting miR-3165 may be a potential therapeutic strategy in BCa treatment. Our study provides new insights into the understanding of molecular mechanism by which METTL14 regulates BCa progression and offer novel and potential targets for BCa treatment.

The Role of Circular RNAs in the Carcinogenesis of Bladder Cancer

Circular RNAs (circRNAs) are a group of transcripts with enclosed configurations which can regulate gene expression. These transcripts have important roles in normal development and in the pathogenesis of disorders. Recent evidence has supported involvement of circRNAs in the development of bladder cancer. Several circRNAs such as circ_0058063, hsa-circRNA-403658, circPDSS1, circCASC15, circRNA-MYLK, and circRNA_103809 have been upregulated in bladder cancer samples. On the other hand, hsa_circ_0137606, BCRC-3, circFUT8, hsa_circ_001598, circSLC8A1, hsa_circ_0077837, hsa_circ_0004826, and circACVR2A are among downregulated circRNAs in bladder cancer. Numerous circRNAs have diagnostic or prognostic value in bladder cancer. In this review, we aim to outline the latest findings about the role of circRNAs in bladder cancer and introduce circRNAs for further investigations as therapeutic targets.

The profile analysis of circular RNAs in cervical cancer

Cervical cancer (CC) is the third most common cancer among women and has a high mortality rate at the advanced stage. The mechanisms underlying the development and progression of CC are still elusive. Circular RNAs (circRNAs) play an important role in various physiological and pathological processes. The aim of this study was to identify the circRNAs significantly associated with cervical squamous cell carcinoma (CSCC), in order to discover novel diagnostic markers and elucidate their mechanistic basis.The circRNA expression profiles of CSCC and paired para-cancerous cervical tissues was downloaded from the Gene Expression Omnibus. Bioinformatics analysis were used to screen for the differentially expressed circRNAs (DECRs). The expression levels of hsa_circ_0000745, hsa_circ_0084927, hsa_circ_0002762, hsa_circ_0075341, hsa_circ_0007905, hsa_circ_0031027, hsa_circ_0065898, hsa_circ_0070190, and hsa_circ_0078383 were verified in CC and normal cervical tissues by quantitative real-time PCR.A total of 197 DECRs were identified between the CSCC and normal tissues, including 87 upregulated and 110 downregulated circRNAs. In addition, 37 miRNAs were predicted for the upregulated circRNAs and 39 for the downregulated circRNAs. Functional analysis showed that the DECRs were associated with positive regulation of substrate adhesion-dependent cell spreading, metabolism, positive regulation of GTPase activity, protein regulation, and intercellular adhesion. The MAPK signaling pathway that plays a significant role in the progression of CC, was also enriched. Consistent with the in-silico analysis, hsa_circ_0000745, hsa_circ_0084927, hsa_circ_0002762, hsa_circ_0007905 were upregulated and hsa_circ_0078383 was downregulated in CC tissues (P < .001), whereas hsa_circ_0075341 (P < .001) and hsa_circ_0031027 (P = .001) showed opposite trends.We identified novel diagnostic and therapeutic biomarkers of CSCC along with the mechanistic basis.

The Emerging Functions of Circular RNAs in Bladder Cancer

Simple Summary

The role of circular RNAs has made breakthroughs in understanding the mechanisms of tumor development. Bladder cancer has an increasing incidence, high recurrence rate, high metastatic potential, poor prognosis, and susceptibility to chemotherapy resistance. Thus, it is essential to identify molecules related to the tumorigenesis of bladder cancer. In this review, we summarize current knowledge about the expression of circular RNAs in bladder cancer and their implications in vesical carcinogenesis. We further discuss the limitations of existing studies and provide an outlook for future studies in the hopes of better revealing the association between circular RNAs and bladder cancer.

Abstract

Bladder cancer (BC) is among the top ten most common cancer types worldwide and is a serious threat to human health. Circular RNAs (circRNAs) are a new class of non-coding RNAs generated by covalently closed loops through back-splicing. As an emerging research hotspot, circRNAs have attracted considerable attention due to their high conservation, stability, abundance, and specificity of tissue development. Accumulating evidence has revealed different form of circRNAs are closely related to the malignant phenotype, prognosis and chemotherapy resistance of BC, suggesting that different circRNAs may be promising biomarkers and have therapeutic significance in BC. The intention of this review is to summarize the mechanisms of circRNA-mediated BC progression and their diagnostic and prognostic value as biomarkers, as well as to further explore their roles in chemotherapy resistance.

The Roles of CircRNAs in Bladder Cancer: Biomarkers, Tumorigenesis Drivers, and Therapeutic Targets

Bladder cancer (BCa) is the most prevalent malignancy of the urinary system. Circular RNAs (circRNAs), a novel subtype of non-coding RNAs, play a crucial role in physiological and developmental processes. CircRNAs mainly function as regulators of splicing process and transcription, microRNA sponges, and protein brackets. Recent advances in understanding the pathogenesis of BCa have led to the identification of an abundance of dysregulated circRNAs associated with BCa. These aberrantly expressed circRNAs eventually lead to abnormalities in biological, genetic, and epigenetic information. In this review, we introduce the potential of circRNAs as biomarkers for BCa diagnosis and prognosis. Notably, diverse mechanisms have been proposed for circRNAs driving carcinogenesis, including increasing cell proliferation, promoting invasive and migratory capacity, enhancing endothelial–mesenchymal transition, sustaining stemness, and enabling resistance to chemotherapy. Importantly, a full understanding of circRNA mechanisms is needed to mine promising therapeutic approaches for targeting BCa. In this paper, we present the latest advances in circRNAs and systemically summarize the characteristics and mechanisms of circRNAs in BCa, providing potential perspectives for BCa treatment.

CircRNAs: Emerging Bladder Cancer Biomarkers and Targets

Circular RNAs (circRNAs) are newly discovered intriguing RNAs due to the covalently closed loop structure, high stability, tissue specificity, and functional diversity. In recent years, a large number of circRNAs have been identified through high-throughput sequencing technology and bioinformatics methods, the abnormal expression of circRNAs are closely related to many diseases including bladder cancer (BC). CircRNAs have been proven to have several functions, such as acting as a regulator of parental gene transcription, miRNA sponge and interacting with proteins to regulate its expression. In addition, some circRNAs have been identified to encode proteins. CircRNAs have the characteristics of high abundance, high stability, wide distribution in body fluids, tissue specificity, and developmental stage specificity, which determine that circRNAs has great potential to be utilized as biomarkers for BC. Herein, we briefly summarize the biogenesis, functions and roles, and the current research progress of circRNAs in BC with a focus on the potential application for BC diagnosis, treatment, and prognosis.

Cancer-related circular RNA: diverse biological functions

Noncoding RNAs, including long noncoding RNAs (lncRNAs), microRNAs (miRNAs) and circular RNAs (circRNAs), are involved in regulating biological functions. In recent decades, miRNAs and lncRNAs have both inspired a wave of research, but the study of circRNA functions is still in its infancy. Studies have found that circRNAs actively participate in the occurrence and development of various diseases, which emphasizes the importance of circRNAs. Here, we review the features and classification of circRNAs and summarize their functions. Then, we briefly describe how to analyze circRNAs by bioinformatics procedures. In addition, the relationship between circRNAs and cancers is discussed with an emphasis on proving whether circRNAs can be potential biomarkers for the prognosis and diagnosis of cancer.

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

Circular RNAs (circRNAs), which are single-stranded closed-loop RNA molecules lacking terminal 5′ caps and 3′ poly(A) tails, are attracting increasing scientific attention for their crucial regulatory roles in the occurrence and development of various diseases. With the rapid development of high-throughput sequencing technologies, increasing numbers of differentially expressed circRNAs have been identified in bladder cancer (BCa) via exploration of the expression profiles of BCa and normal tissues and cell lines. CircRNAs are critically involved in BCa biological behaviours, including cell proliferation, tumour growth suppression, cell cycle arrest, apoptosis, invasion, migration, metastasis, angiogenesis, and cisplatin chemoresistance. Most of the studied circRNAs in BCa regulate cancer biological behaviours via miRNA sponging regulatory mechanisms. CircRNAs have been reported to be significantly associated with many clinicopathologic characteristics of BCa, including tumour size, grade, differentiation, and stage; lymph node metastasis; tumour numbers; distant metastasis; invasion; and recurrence. Moreover, circRNA expression levels can be used to predict BCa patients’ survival parameters, such as overall survival (OS), disease-free survival (DFS), and progression-free survival (PFS). The abundance, conservation, stability, specificity and detectability of circRNAs render them potential diagnostic and prognostic biomarkers for BCa. Additionally, circRNAs play crucial regulatory roles upstream of various signalling pathways related to BCa carcinogenesis and progression, reflecting their potential as therapeutic targets for BCa. Herein, we briefly summarize the expression profiles, biological functions and mechanisms of circRNAs and the potential clinical applications of these molecules for BCa diagnosis, prognosis, and targeted therapy.

SLC12A8 plays a key role in bladder cancer progression and EMT

Bladder cancer is the most common malignant tumor of the urinary system. The intention of the present research is to explore the prognostic value and biological function of solute carrier family 12 member 8 (SLC12A8) in bladder cancer. The analysis based on the TCGA and ONCOMINE database revealed that the expression of SLC12A8 in bladder cancer was notably increased compared with the normal group. SLC12A8 expression was notably correlated with the age, pathological stage, T-stage, and lymph node metastasis of bladder cancer patients. Moreover, the patients’ overall survival was notably shorter in the high SLC12A8 group. Compared with the control, SLC12A8 upregulation enhanced the proliferative, invasive, and migratory capacities of bladder cancer cells and promoted the expression of epithelial–mesenchymal transition (EMT) protein markers including β-catenin, vimentin, snail, and slug, while reduced the expression of E-cadherin. In the case of downregulated SLC12A8 expression, the proliferative, invasive, and migratory capacities of bladder cancer cells and the expression of EMT protein markers presented the opposite trend. This study demonstrated that SLC12A8 was highly correlated with oncogenesis and progression of bladder cancer, indicating that SLC12A8 may be a meaningful biomarker for initial diagnosis and early treatment of bladder cancer.

Circular RNAs and Bladder Cancer

Bladder cancer (BC) is the most common urinary system malignancy and is a serious threat to human health. Circular RNAs (circRNAs) are members of a newly defined class of noncoding RNAs (ncRNAs) that can regulate gene expression at the transcriptional or posttranscriptional level. Studies have shown that circRNAs are related to the clinicopathological characteristics, prognosis, and chemosensitivity of BC, and basic research has further confirmed that changes in the expression of circRNAs in BC are closely related to various tumor biological functions. CircRNAs promote tumor development by interacting with miRNAs to regulate transcription factors and both classical and nonclassical tumor signaling pathways. The nonclassical signaling pathways are related to cell cycle progression, epithelial–mesenchymal transition (EMT), extracellular matrix maintenance, and tumor stem cell maintenance. In this article, the relationships between circRNAs and the clinical characteristics of BC are reviewed, and the molecular mechanisms by which circRNAs promote tumor development are explored.

MiR-362-5p, Which Is Regulated by Long Non-Coding RNA MBNL1-AS1, Promotes the Cell Proliferation and Tumor Growth of Bladder Cancer by Targeting QKI

In this study, we found miR-362-5p was upregulated in bladder cancer tissues and we predicted that QKI is potential a target of miR-362-5p and MBNL1-AS1 might be able to directly target to miR-362-5p. We attempted to evaluate whether miR-362-5p could play its roles in bladder cancer through regulating QKI (quaking) and whether the expression and function of miR-362-5p could be mediated by lncRNA MBNL1-AS1. We performed the gain- and loss-function experiments to explore the association between miR-362-5p expression and bladder cancer proliferation. In vivo, the nude mice were injected with miR-362-5p knockdown SW780 cells to assess the effects of miR-362-5p on tumor growth. The results showed upregulation of miR-362-5p promoted cell proliferation of bladder cancer cells. MBNL1-AS1 and QKI could directly bind with miR-362-5p, and knockdown of MBNL1-AS1 or QKI could abrogate the regulatory effects of miR-362-5p on bladder cancer cell proliferation. Furthermore, downregulation of miR-362-5p inhibited bladder tumor growth and increased QKI expression. Our data unveiled that miR-362-5p may play an oncogenic role in bladder cancer through QKI and MBNL1-AS1 might function as a sponge to mediate the miR-362-5p expression and function.

Circ_0006332 promotes growth and progression of bladder cancer by modulating MYBL2 expression via miR-143

In this study, we analyzed the role of circular RNAs in the growth and progression of bladder cancer. Direct Sanger sequencing and quantitative RT-PCR analysis showed that circ_0006332 was significantly upregulated in bladder cancer tissues. Sequencing analysis showed that circ_0006332 is generated from splicing of exons 8 and 9 of the MYBL2 transcript. Fluorescence in situ hybridization analysis showed that circ_0006332 was localized to the cytoplasm of bladder cancer cells. Dual luciferase reporter assays showed that miR-143 specifically bound to circ_0006332 and the 3’UTR of MYBL2. High expression of circ_006332 correlated with tumor-node-metastasis stages and muscular invasion in bladder cancer patients. Knockdown of circ_0006332 in bladder cancer cells decreased proliferation, colony formation and invasiveness. Circ_0006332 knockdown increased E-cadherin levels and decreased Vimentin, CCNB1 and P21 protein expression. This suggests that circ_0006332 promotes epithelial–mesenchymal transition and cell cycle progression. In vivo experiments in nude mice showed that circ_0006332 knockdown bladder cancer cells form significantly smaller tumors than the controls. Our study demonstrates that circ_0006332 promotes the growth and progression of bladder cancer by modulating MYBL2 expression by acting as a sponge for miR-143. Circ_0006332 is thus a potential early diagnostic marker of bladder cancer.