Down-Regulation of Circular RNA_000926 Attenuates Renal Cell Carcinoma Progression through miRNA-411-Dependent CDH2 Inhibition

Genome-wide association study of therapeutic response to statin drugs in cardiovascular disease

Cardiovascular disease (CVD) is one of the main causes of death in the world. The increased level of blood cholesterol is significantly correlated to CVD incidents. Statins are a group of drugs that decrease the synthesis of cholesterol in the liver by inhibiting the final enzyme of the pathway named HMG-CoA reductase. Several investigations showed that different patients give different responses to the administration of statin drugs according to their genetic background. In this research study, using Genome-Wide Association Studies (GWAS) data analysis methods, such as the SimpleM statistical approach and genomic connection matrix, we tried to discover the novel candidate SNPs that were involved in response to statin drugs. The investigation was carried out using 3,221 cardiovascular patients' data about genotypes and phenotypes of two important parameters including total cholesterol, and LDL level, in response to statin administration. Functional annotation of nearest genes to candidate SNPs was also carried out by using comprehensive databases and tools such as BioMart-Ensembl, UCSC, NCBI, and WebGestalt software. Our results represented eight novel SNPs (rs10820084, rs4803750, rs10989887, rs1966503, rs17502794, rs10785232, rs484071, rs4785621) significantly associated with statin response in different individual cardiovascular patients for the first time. In addition, the groups of genes that are close to the SNPs were also represented and evaluated in detail. Our results illustrated that some of the genes such as BAAT, BCL3, and CMTM6 have a direct functional impact on cholesterol level or LDL biosynthesis which confirmed the effects of neighbor SNPs on the response to statin drugs. Today, finding the loci, genes, and molecular mechanisms involved in the response to drugs is of great importance in pharmacogenomics and personalized medicine.

CircPRELID2 functions as a promoter of renal cell carcinoma through the miR-22-3p/ETV1 cascade

BACKGROUND

Emerging evidence has indicated that a number of circular RNAs (circRNAs) participate in renal cell carcinoma (RCC) carcinogenesis. Nevertheless, the activity and molecular process of circPRELID2 (hsa_circ_0006528) in RCC progression remain unknown.

METHODS

CircPRELID2, miR-22-3p and ETS variant 1 (ETV1) levels were gauged by qRT-PCR. Effect of the circPRELID2/miR-22-3p/ETV1 axis was evaluated by detecting cell growth, motility, and invasion. Immunoblotting assessed related protein levels. The relationships of circPRELID2/miR-22-3p and miR-22-3p/ETV1 were confirmed by RNA immunoprecipitation (RIP), luciferase reporter or RNA pull-down assay.

RESULTS

CircPRELID2 was up-regulated in RCC. CircPRELID2 silencing suppressed RCC cell growth, motility and invasion. Moreover, circPRELID2 silencing weakened M2-type macrophage polarization in THP1-induced macrophage cells. CircPRELID2 sequestered miR-22-3p, and circPRELID2 increased ETV1 expression through miR-22-3p. Moreover, the inhibitory impact of circPRELID2 silencing on RCC cell malignant behaviors was mediated by the miR-22-3p/ETV1 axis. Furthermore, circPRELID2 knockdown in vivo hampered growth of xenograft tumors.

CONCLUSION

Our study demonstrates that circPRELID2 silencing can mitigate RCC malignant development through the circPRELID2/miR-22-3p/ETV1 axis, highlighting new therapeutic targets for RCC treatment.

Exosomes in renal cell carcinoma: challenges and opportunities

Renal cell carcinoma (RCC) is the most common type of kidney cancer that accounts for approximately 2-3% of adult malignancies. Among the primary treatment methods for this type of cancer are surgery and targeted treatment. Still, due to less than optimal effectiveness, there are problems such as advanced distant metastasis, delayed diagnosis, and drug resistance that continue to plague patients. In recent years, therapeutic advances have increased life expectancy and effective treatment in renal cell carcinoma patients. One of these methods is the use of stem cells. Although the therapeutic effects of stem cells, especially mesenchymal stem cells, are still impressive, today, extracellular vesicles (EVs) as carrying molecules and various mediators in intercellular communications, having a central role in tumorigenesis, metastasis, immune evasion, and drug response, and on the other hand, due to its low immunogenicity and strong regulatory properties of the immune system, has received much attention from researchers and doctors. Despite the increasing interest in exosomes as the most versatile type of EVs, the heterogeneity of their efficacy presents challenges and, on the other hand, exciting opportunities for diagnostic and clinical interventions.In the upcoming article, we will review the various aspects of exosomes' effects in the prevention, treatment, and progress of renal cell carcinoma and also ways to optimize them to strengthen their positive sides.

Circular RNAs in renal cell carcinoma: from mechanistic to clinical perspective

CircRNAs, a special type of noncoding RNAs characterized by their stable structure and unique abilities to form backsplicing loops, have recently attracted the interest of scientists. These RNAs are abundant throughout the body and play important roles such as microRNA sponges, templates for transcription, and regulation of protein translation and RNA-binding proteins. Renal cancer development is highly correlated with abnormal circRNA expression in vivo. CircRNAs are currently considered promising targets for novel therapeutic approaches as well as possible biomarkers for prognosis and diagnosis of various malignancies. Despite our growing understanding of circRNA, numerous questions remain unanswered. Here, we address the characteristics of circRNAs and their function, focusing in particular on their impact on drug resistance, metabolic processes, metastasis, cell growth, and programmed cell death in renal cancer. In addition, the application of circRNAs as prognostic and diagnostic biomarkers will be discussed.

HBx promotes hepatocellular carcinoma progression by repressing the transcription level of miR-187-5p

HBV-associated hepatitis B virus x protein (HBx) plays multiple roles in the development of hepatocellular carcinoma. In our prior study, we discovered that miR-187-5p expression was inhibited by HBx. To investigate the underlying molecular mechanism of HBx-mediated miR-187-5p downregulation in hepatocellular carcinoma cells, effects of HBx and miR-187-5p on hepatoma carcinoma cell were observed, as well as their interactions. Through in vitro and in vivo experiments, we demonstrated that overexpression of miR-187-5p inhibited proliferation, migration, and invasion. Simultaneously, we observed a dysregulation in the expression of miR-187-5p in liver cancer cell lines, which may be attributed to transcriptional inhibition through the E2F1/FoxP3 axis. Additionally, we noted that HBx protein is capable of enhancing the expression of E2F1, a transcription factor that promotes the expression of FoxP3. In conclusion, our results suggest that the inhibitory effect of HBx on miR-187-5p is mediated through the E2F1/FoxP3 axis. As shown in this work, HBx promotes hepatoma carcinoma cell proliferation, migration, and invasion through the E2F1/FoxP3/miR-187 axis. It provides a theoretical basis for finding therapeutic targets that will help clinic treatment for HCC.

The function and mechanisms of action of circular RNAs in Urologic Cancer

Kidney, bladder, and prostate cancer are the three major tumor types of the urologic system that seriously threaten human health. Circular RNAs (CircRNAs), special non-coding RNAs with a stabile structure and a unique back-splicing loop-forming ability, have received recent scientific attention. CircRNAs are widely distributed within the body, with important biologic functions such as sponges for microRNAs, as RNA binding proteins, and as templates for regulation of transcription and protein translation. The abnormal expression of circRNAs in vivo is significantly associated with the development of urologic tumors. CircRNAs have now emerged as potential biomarkers for the diagnosis and prognosis of urologic tumors, as well as targets for the development of new therapies. Although we have gained a better understanding of circRNA, there are still many questions to be answered. In this review, we summarize the properties of circRNAs and detail their function, focusing on the effects of circRNA on proliferation, metastasis, apoptosis, metabolism, and drug resistance in kidney, bladder, and prostate cancers.

Emerging roles of circular RNAs in cancer therapy-induced cardiotoxicity

Cancer therapy-induced cardiotoxicity (CTIC) is an important cause of death in cancer survivors which often results in the withdrawal or discontinuation of drugs. The underlying mechanisms of CTIC remain unclear. Circular RNAs (circRNAs) are a class of non-coding regulatory RNA molecules which have emerged in recent years. They are generated by back splicing and have powerful biological functions, including transcription and splicing, isolating or building macromolecular scaffolds to interfere with microRNA activity and signaling pathways, and acting as templates for translation. Moreover, circRNAs demonstrate high abundance and significant stability. CircRNAs can be used as novel biomarkers because they often function in a cell-type and tissue-specific manner. CircRNAs have attracted increasing attention in cardiovascular disease research, and recent studies exploring the role of circRNAs in CTIC have had promising results. This review will summarize the current understanding of circRNAs' biogenesis, regulation and function. Their clinical potential as biomarkers, therapeutic agents and drug targets will also be explored.

Circular RNA circMTO1 suppressed the progression of renal cell carcinoma progression by sponging miR-211 and miR-204

Despite considerable improvements in renal cell carcinoma (RCC) diagnostic and therapeutic strategy, the clinical prognosis of patients is far from satisfactory due to its recurrence and metastasis. Here, we attempted to explore the role of circMTO1 in RCC progression, and the underlying mechanism was further elucidated. We first detected the expression of circMTO1 in 90 pairs of RCC tissues and adjacent normal tissues using qRT-PCR. Besides, circMTO1, miR-211, miR-204 and KLF6 expression levels in RCC cells were also measured using qRT-PCR. MTT assay, cell migration, flow cytometry analysis, qRT-PCR and western blotting analysis were applied to evaluating the effect of circMTO1 in RCC cells. The bioinformatics analysis and the rescue experiment were devoted to the underlying mechanism. The results demonstrated CircMTO1 expression was significantly down-regulated in RCC tissues and cell lines. Besides, CircMTO1 inhibited cell proliferation, migration and invasion, induced apoptosis in RCC cells. In addition, CircMTO1 serves as a sponge for miR-211 and miR-204, KLF6 is a direct target of miR-211 and miR-204. Furthermore, circMTO1 and KLF6 overexpression rescued the suppression of miR-211/204 in RCC cell proliferation. In short, circMTO1 repressed RCC progression by regulating KLF6 via sponging miR-211 and miR-204, which may provide new idea of diagnosis and treatment in renal cell carcinoma.

Circ_000829 Plays an Anticancer Role in Renal Cell Carcinoma by Suppressing SRSF1-Mediated Alternative Splicing of SLC39A14

Background

Covalently closed circular RNAs (circRNAs) play critical oncogenic or anticancer roles in various cancers including renal cell carcinoma (RCC), pointing to their regulation as a promising strategy against development of RCC. We, thus, studied the tumor-suppressive role of circ_000829 in RCC through in vitro and in vivo experiments.

Methods

The expression of circ_000829 was validated in clinical RCC tissues and RCC cell lines. Based on ectopic expression and knockdown experiments, we examined the interactions among circ_000829, serine and arginine rich splicing factor 1 (SRSF1), and solute carrier family 39 member 14 (SLC39A14, zinc transporter). Then, the effects of circ_000829, SRSF1, and SLC39A14 on cell cycle distribution and proliferation in vitro and on tumor growth in vivo were evaluated in RCC cells.

Results

Circ_000829 was poorly expressed in RCC tissues and cells, while SRSF1 was highly expressed. Restoration of circ_000829 reduced the levels of SRSF1 and SLC39A14B, thereby repressing the RCC cell proliferation in vitro and tumor growth in vivo. Meanwhile, overexpression of SRSF1 and SLC39A14B promoted the proliferation and cell cycle entry of RCC cells. Mechanistically, circ_000829 directly bound to SRSF1, and SRSF1 enhanced the expression of SLC39A14B by mediating the alternative splicing of SLC39A14. SLC39A14B upregulation negated the effect of SLC39A14 knockdown on RCC cell proliferation.

Conclusion

Hence, this study suggests the antiproliferative role of circ_000829 in RCC growth and further elucidates the underlying mechanism involving the inhibited SRSF1-mediated alternative splicing of SLC39A14 mRNA.

Use of Circular RNAs in Diagnosis, Prognosis and Therapeutics of Renal Cell Carcinoma

Renal cell carcinoma is the most common type of kidney cancer, representing 90% of kidney cancer diagnoses, and the deadliest urological cancer. While the incidence and mortality rates by renal cell carcinoma are higher in men compared to women, in both sexes the clinical characteristics are the same, and usually unspecific, thereby hindering and delaying the diagnostic process and increasing the metastatic potential. Regarding treatment, surgical resection remains the main therapeutic strategy. However, even after radical nephrectomy, metastasis may still occur in some patients, with most metastatic renal cell carcinomas being resistant to chemotherapy and radiotherapy. Therefore, the identification of new biomarkers to help clinicians in the early detection, and treatment of renal cell carcinoma is essential. In this review, we describe circRNAs related to renal cell carcinoma processes reported to date and propose the use of some in therapeutic strategies for renal cell carcinoma treatment.

The functions, oncogenic roles, and clinical significance of circular RNAs in renal cell carcinoma

Renal cell carcinoma (RCC) is the most common form of malignancy affecting the kidneys. Circular RNAs (circRNAs) are non-coding RNAs that are derived from exonic or intronic sequences through a selective shearing process. There is growing evidence that these circRNAs can influence a range of biological pathways by serving as protein decoys, microRNA sponges, regulators of transcriptional activity, or templates for protein translation. The dysregulation of circRNA expression patterns is a hallmark of RCC and other cancer types, and there is strong evidence that these RNA species can play central roles in the onset and progression of RCC tumors. In the present review, we summarized recent findings on the functional roles and clinical impacts of circRNAs in RCC. Further, we discussed their potential utility as diagnostic biomarkers or targets for therapeutic intervention.

Dysregulation of miR-411 in cancer: Causative factor for pathogenesis, diagnosis and prognosis

MiRNA accounts for 1-3% of genes but regulates more than 30% of gene expression in humans. This article analyzes the current deficiencies and challenges of miR-411 research and looks forward to the prospects of miR-411 in cancer. MiR-411 is a non-coding RNA located on chromosome 14. MiR-411 is abnormally expressed in a variety of cancers. The dysregulation of miR-411 can affect cancer cell proliferation, invasion, migration, apoptosis, colony formation, etc. miR-411 can be regulated by different lncRNAs and circRNAs. By targeting multiple genes, miR-411 participates in the activation of the MAPK signaling pathway, PI3K/AKT/mTOR signaling pathway, p53 signaling pathway, Ras signaling pathway, NF-κB signaling pathway, and Wnt/β-catenin signaling pathway. The expression of miR-411 is related to the diagnosis, prognosis, and sensitivity of drugs in cancer patients. In conclusion, this work outlines the molecular mechanisms and cellular functions of aberrant expression of miR-411 and its target genes in cancer to reveal its potential value in diagnosis, prognosis, and drug sensitivity.

hsa_circ_0000285 facilitates thyroid cancer progression by regulating miR-127-5p/CDH2

Thyroid cancer (THCA) is a leading endocrine cancer and becomes the fifth most commonly diagnosed malignancy in females. It is confirmed that circular RNAs (circRNAs) perform regulatory potencies in the pathological progress of THCA. Our purpose was to certify the trait of hsa_circ_0000285 (circ_0000285) and investigate its modulatory mechanism in THCA progression. We identified the expression profile of hsa_circ_0000285 in THCA by conducting qRT-PCR assay. Therewith, the potential of hsa_circ_0000285 in THCA development was determined with a set of functional experiments, including CCK-8, wound healing assay, Western blot, and xenograft model. The molecular mechanism underlying hsa_circ_0000285 was investigated with bioinformatic analysis, RIP and dual-luciferase reporter experiments. As opposed to normal samples and cells, hsa_circ_0000285 level was overtly increased in THCA specimens and cells. The downregulation of hsa_circ_0000285 weakened the proliferative and migratory capacity of THCA cells and promoted cell apoptosis. In addition, hsa_circ_0000285 silence suppressed the tumor growth of xenograft model mice in vivo. Notably, we demonstrated that hsa_circ_0000285 might target miR-127-5p/CDH2 axis in THCA. Afterward, our findings manifested that miR-127-5p attenuation blocked the function of hsa_circ_0000285 depletion in THCA cells. In the final step, CDH2 was proven to mediate the repressive potency of miR-127-5p in the malignant behaviors of THCA. Mechanistically, hsa_circ_0000285 induced the development of THCA via functioning as a competing endogenous RNA (ceRNA) of miR-127-5p to enhance CDH2 expression, which provided a new perspective for THCA therapy.

CircRNAs as Novel Biomarkers and Therapeutic Targets in Renal Cell Carcinoma

Circular RNAs (circRNAs) are a type of long non-coding RNA with covalently closed loops that are naturally resistant to exoribonuclease. With the rapid development of high-throughput sequencing technologies and bioinformatics, increasing data suggest that circRNAs are abnormally expressed in renal cell carcinoma (RCC) and act as important regulators of RCC carcinogenesis and progression. CircRNAs play important biological roles in modulating cell proliferation, migration, invasion, apoptosis, and gemcitabine chemoresistance in RCC. Most of the circRNAs studied in RCC have been reported to be significantly associated with many clinicopathologic characteristics and survival parameters of RCC. The stability and specificity of circRNAs enable them potential molecular markers for RCC diagnosis and prognosis. Moreover, circRNAs have emerged as targets for developing new therapies, because they can regulate various signaling pathways associated with RCC initiation and progression. In this review, we briefly summarize the biogenesis, degradation, and biological functions of circRNAs as well as the potential clinical applications of these molecules for RCC diagnosis, prognosis, and targeted therapy.

Identification and verification of the molecular mechanisms and prognostic values of the cadherin gene family in gastric cancer

While cadherin (CDH) genes are aberrantly expressed in cancers, the functions of CDH genes in gastric cancer (GC) remain poorly understood. The clinical significance and molecular mechanisms of CDH genes in GC were assessed in this study. Data from a total of 1226 GC patients included in The Cancer Genome Atlas (TCGA) and Kaplan–Meier plotter database were used to independently explore the value of CDH genes in clinical application. The TCGA RNA sequencing dataset was used to explore the molecular mechanisms of CDH genes in GC. Using enrichment analysis tools, CDH genes were found to be related to cell adhesion and calcium ion binding in function. In TCGA cohort, 12 genes were found to be differentially expressed between GC para-carcinoma and tumor tissue. By analyzing GC patients in two independent cohorts, we identified and verified that CDH2, CDH6, CDH7 and CDH10 were significantly associated with a poor GC prognosis. In addition, CDH2 and CDH6 were used to construct a GC risk score signature that can significantly improve the accuracy of predicting the 5-year survival of GC patients. The GSEA approach was used to explore the functional mechanisms of the four prognostic CDH genes and their associated risk scores. It was found that these genes may be involved in multiple classic cancer-related signaling pathways, such as the Wnt and phosphoinositide 3-kinase signaling pathways in GC. In the subsequent CMap analysis, three small molecule compounds (anisomycin, nystatin and bumetanide) that may be the target molecules that determine the risk score in GC, were initially screened. In conclusion, our current study suggests that four CDH genes can be used as potential biomarkers for GC prognosis. In addition, a prognostic signature based on the CDH2 and CDH6 genes was constructed, and their potential functional mechanisms and drug interactions explored.

Diverse Roles and Therapeutic Potentials of Circular RNAs in Urological Cancers

Circular RNAs (circRNAs) are a novel class of noncoding RNAs, which are mainly formed as a loop structure at the exons caused by noncanonical splicing; they are much more stable than linear transcripts; recent reports have suggested that the dysregulation of circRNAs is associated with the occurrence and development of diseases, especially various human malignancies. Emerging evidence demonstrated that a large number of circRNAs play a vital role in a series of biological processes such as tumor cell proliferation, migration, drug resistance, and immune escape. Additionally, circRNAs were also reported to be potential prognostic and diagnostic biomarkers in cancers. In this work, we systematically summarize the biogenesis and characteristics of circRNAs, paying special attention to potential mechanisms and clinical applications of circRNAs in urological cancers, which may help develop potential therapy targets for urological cancers in the future.

Circular RNAs in kidney disease and cancer

Circular RNAs (circRNAs) are a class of endogenously expressed regulatory RNAs with a single-stranded circular structure. They are generated by back splicing and their expression can be tightly regulated by RNA binding proteins. Cytoplasmic circRNAs can function as molecular sponges that inhibit microRNA-target interactions and protein function or as templates for the efficient generation of peptides via rolling circle amplification. They can also act as molecular scaffolds that enhance the reaction kinetics of enzyme-substrate interactions. In the nucleus, circRNAs might facilitate chromatin modifications and promote gene expression. CircRNAs are resistant to degradation and can be packaged in extracellular vesicles and transported in the circulation. Initial studies suggest that circRNAs have roles in kidney disease and associated cardiovascular complications. They have been implicated in hypertensive nephropathy, diabetic kidney disease, glomerular disease, acute kidney injury and kidney allograft rejection, as well as in microvascular and macrovascular complications of chronic kidney disease, including atherosclerotic vascular disease. In addition, several circRNAs have been reported to have oncogenic or tumour suppressor roles or to regulate drug resistance in kidney cancer. The available data suggest that circRNAs could be promising diagnostic and/or prognostic biomarkers and potential therapeutic targets for kidney disease, cardiovascular disease and kidney cancer.

Circular RNAs in renal cell carcinoma: Functions in tumorigenesis and diagnostic and prognostic potentials

Circular RNAs (circRNAs) are non-coding RNAs with closed ends which makes them resistant to degrading enzyme RNAse R. These RNA molecules show cell, tissue or organ specific expression. Regulatory functions have been reported for a number of circRNAs. Particularly, they have been found to affect cell cycle and control cell proliferation. CircRNAs are involved in physiological processes like natural organ development. Their dysregulation in high-throughput technologies have been shown in a growing number of diseases especially many types of cancers such as renal cell carcinoma (RCC). Differentially expressed circRNAs in RCC tissues compared to normal tissues may affect carcinogenesis process. Overexpressed circRNAs promote tumorigenic functions of RCC cell lines while down-regulated transcripts repress them. Both dysregulated circRNAs are correlated with clinicopathological features, prognosis and survival in RCC patients which along with their acceptable diagnostic values suggest them as potential biomarkers in diagnosis or prediction of prognosis of RCC patients. In this review, we have assessed tumorigenic or tumor-suppressing effects of circRNAs and also their diagnostic and prognostic potentials in RCC.

MicroRNA-411-3p inhibits bleomycin-induced skin fibrosis by regulating transforming growth factor-β/Smad ubiquitin regulatory factor-2 signalling

Skin fibrosis, which is characterized by fibroblast proliferation and increased extracellular matrix, has no effective treatment. An increasing number of studies have shown that microRNAs (miRNAs/miRs) participate in the mechanism of skin fibrosis, such as in limited cutaneous systemic sclerosis and pathological scarring. The objective of the present study was to determine the role of miR‐411‐3p in bleomycin (BLM)‐induced skin fibrosis and skin fibroblast transformation. Using Western blot analysis and real‐time quantitative polymerase chain reaction assess the expression levels of miR‐411‐3p, collagen (COLI) and transforming growth factor (TGF)‐β/Smad ubiquitin regulatory factor (Smurf)‐2/Smad signalling factors both in vitro and in vivo with or without BLM. To explore the regulatory relationship between miR‐411‐3p and Smurf2, we used the luciferase reporter assay. Furthermore, miR‐411‐3p overexpression was identified in vitro and in vivo via transfection with Lipofectamine 2000 reagent and injection. Finally, we tested the dermal layer of the skin using haematoxylin and eosin and Van Gieson's staining. We found that miR‐411‐3p expression was decreased in bleomycin (BLM)‐induced skin fibrosis and fibroblasts. However, BLM accelerated transforming growth factor (TGF)‐β signalling and collagen production. Overexpression of miR‐411‐3p inhibited the expression of collagen, F‐actin and the TGF‐β/Smad signalling pathway factors in BLM‐induced skin fibrosis and fibroblasts. In addition, miR‐411‐3p inhibited the target Smad ubiquitin regulatory factor (Smurf)‐2. Furthermore, Smurf2 was silenced, which attenuated the expression of collagen via suppression of the TGF‐β/Smad signalling pathway. We demonstrated that miR‐411‐3p exerts antifibrotic effects by inhibiting the TGF‐β/Smad signalling pathway via targeting of Smurf2 in skin fibrosis.

Circular RNAs as Novel Diagnostic Biomarkers and Therapeutic Targets in Kidney Disease

Circular RNAs (circRNAs) are a novel type of non-coding RNAs that have aroused growing attention in this decade. They are widely expressed in eukaryotes and generally have high stability owing to their special closed-loop structure. Many circRNAs are abundant, evolutionarily conserved, and exhibit cell-type-specific and tissue-specific expression patterns. Mounting evidence suggests that circRNAs have regulatory potency for gene expression by acting as microRNA sponges, interacting with proteins, regulating transcription, or directly undergoing translation. Dysregulated expression of circRNAs were found in many pathological conditions and contribute to the pathogenesis and progression of various disorders, including renal diseases. Recent studies have revealed that circRNAs may serve as novel reliable biomarkers for the diagnosis and prognosis prediction of multiple kidney diseases, such as renal cell carcinoma (RCC), acute kidney injury (AKI), diabetic kidney disease (DKD), and other glomerular diseases. Furthermore, circRNAs expressed by intrinsic kidney cells are shown to play a substantial role in kidney injury, mostly reported in DKD and RCC. Herein, we review the biogenesis and biological functions of circRNAs, and summarize their roles as promising biomarkers and therapeutic targets in common kidney diseases.

Circular RNAs and their role in renal cell carcinoma: a current perspective

Circular RNAs (circRNAs) are a new class of long non-coding RNAs, that results from a special type of alternative splicing referred to as back-splicing. They are widely distributed in eukaryotic cells and demonstrate tissue-specific expression patterns in humans. CircRNAs actively participate in various important biological activities like gene transcription, pre-mRNA splicing, translation, sponging miRNA and proteins, etc. With such diverse biological functions, circRNAs not only play a crucial role in normal human physiology, as well as in multiple diseases, including cancer. In this review, we summarized our current understanding of circRNAs and their role in renal cell carcinoma (RCC), the most common cancer of kidneys. Studies have shown that the expression level of several circRNAs are considerably varied in RCC samples and RCC cell lines suggesting the potential role of these circRNAs in RCC progression. Several circRNAs promote RCC development and progression mostly via the miRNA/target gene axis making them ideal candidates for novel anti-cancer therapy. Apart from these, there are a few circRNAs that are significantly downregulated in RCC and overexpression of these circRNAs leads to suppression of RCC growth. Differential expression patterns and novel functions of circRNAs in RCC suggest that circRNAs can be utilized as potential biomarkers and therapeutic targets for RCC therapy. However, our current understanding of the role of circRNA in RCC is still in its infancy and much comprehensive research is needed to achieve clinical translation of circRNAs as biomarkers and therapeutic targets in developing effective treatment options for RCC.

MiR-145 suppresses the motility of prostate cancer cells by targeting cadherin-2

Metastasis is the main cause of poor prognosis in the advanced prostate cancer in clinic. Accumulating evidences have proposed that cell motility greatly contributes to the multiple steps of the metastatic process. MicroRNA-145 (miR-145) has been found to be downregulated in prostate cancer and serve as a putative tumor suppressor via decrease of cell growth and augmentation of cell death; however, the effects and the underlying mechanisms of miR-145 in prostate cancer cell motility have not been completely clarified. In the current study, we first demonstrated that miR-145 exerted inhibitory effects on the aggressive phenotype of the prostate cancer cells. Based on the bioinformatics analysis of the putative target genes of miR-145, we further experimentally identified a novel mechanism of miR-145 suppressing the aggressive phenotype of prostate cancer cells via directly targeting cadherin-2 (CDH2) protein translation. Re-expression of CDH2 could rescue miR-145-triggered cell migration and invasion defects. Our results suggested that miR-145 suppressed the motility of prostate cancer cells via post-transcriptional downregulation of CDH2 expression, and miR-145-CDH2 pair might serve as a potential target for intervention of prostate cancer metastasis.

CircEHD2, CircNETO2 and CircEGLN3 as Diagnostic and Prognostic Biomarkers for Patients with Renal Cell Carcinoma

Simple Summary

Circular RNA (circRNA) plays an important role in cancer, but little is known about its role in clear cell renal cell carcinoma (ccRCC). The study was designed to analyze the role of circRNAs in ccRCC. We show that circEHD2, circENGLN3, and circNETO2 are upregulated in ccRCC compared with non-malignant renal tissue. Increased circEHD2 levels were significant and independent predictors of progression-free and cancer-specific survival of ccRCC patients. Thus, the analysis of circRNAs may be of diagnostic and prognostic relevance in patients with ccRCC.

Abstract

Background: Circular RNA (circRNA) plays an important role in the carcinogenesis of various tumors. It is assumed that circRNAs have a high tissue and tumor specificity, thus they are discussed as cancer biomarkers. The knowledge about circRNAs in clear cell renal carcinoma (ccRCC) is limited so far, and thus we studied the expression profile of seven circRNAs (circCOL5A1, circEHD2, circEDEM2, circEGNL3, circNETO2, circSCARB1, circSOD2) in a cohort of ccRCC patients. Methods: Fresh-frozen normal and cancerous tissues were prospectively collected from patients with ccRCC undergoing partial/radical nephrectomy. Total RNA was isolated from 121 ccRCC and 91 normal renal tissues, and the circRNA expression profile was determined using quantitative real-time PCR. Results: circEHD2, circENGLN3, and circNETO2 were upregulated in ccRCC compared with non-malignant renal tissue. circENGLN3 expression was highly discriminative between normal and cancerous tissue. None of the circRNAs was correlated with clinicopathological parameters. High circEHD2 and low circNETO2 levels were an independent predictor of a shortened progression-free survival, cancer-specific survival, and overall survival in patients with ccRCC undergoing nephrectomy. Conclusions: The analysis of circRNAs may provide diagnostic and prognostic information. Thus, circRNAs could help to optimize the individual treatment and ultimately improve ccRCC patients’ survival.

Circular RNA ITCH Is a Tumor Suppressor in Clear Cell Renal Cell Carcinoma Metastasis through miR-106b-5p/PDCD4 Axis

High metastasis of clear cell renal cell carcinoma (ccRCC) significantly influenced survival rate of ccRCC patients. Here, we intended to investigate the impacts of circular RNA ITCH (circ-ITCH) on the metastasis of ccRCC. The expression of circ-ITCH in ccRCC tissues and cells was evaluated utilizing qRT-PCR. Transwell assay and wound healing were applied to investigate migration and invasion of ccRCC cells. Target gene prediction and screening and luciferase reporter gene assays were utilized to assess downstream target genes of circ-ITCH. Western blot was utilized to detect metastasis-related protein expression. A xenograft tumor model was established to evaluate the role of circ-ITCH in vivo. Results showed that circ-ITCH was low expressed in ccRCC tissues and cells. Downregulation circ-ITCH promoted cell migration, but overexpressing circ-ITCH inhibited cell migration and invasion in OSRC-2 and SW839 cells. Mechanism investigations claimed that circ-ITCH exerted its metastasis-inhibitory activity via sponging miR-106b-5p and regulating the expression of PDCD4. Conclusively, circ-ITCH suppresses ccRCC metastasis by enforcing PDCD4 expression through binding miR-106b-5p. circ-ITCH may function as a novel diagnostic target to suppress ccRCC metastasis.

Role of Circular RNA in Kidney-Related Diseases

The kidney is vital in maintaining fluid, electrolyte, and acid–base balance. Kidney-related diseases, which are an increasing public health issue, can happen to people of any age and at any time. Circular RNAs (circRNAs) are endogenous RNA that are produced by selective RNA splicing and are involved in progression of various diseases. Studies have shown that various kidney diseases, including renal cell carcinoma, acute kidney injury, and chronic kidney disease, are linked to circRNAs. This review outlines the characteristics and biological functions of circRNAs and discusses specific studies that provide insights into the function and potential of circRNAs for application in the diagnosis and treatment of kidney-related diseases.

Circ_0082182 promotes oncogenesis and metastasis of colorectal cancer in vitro and in vivo by sponging miR-411 and miR-1205 to activate the Wnt/β-catenin pathway

BACKGROUND

Circular RNAs (circRNAs) are a class of endogenous single-strand RNA transcripts with crucial regulation in human cancers. The objective of this study is to investigate the role of circ_0082182 in CRC and its specific functional mechanism.

METHODS

The quantitative real-time polymerase chain reaction (qRT-PCR) was performed to measure the levels of circ_0082182, microRNA-411 (miR-411) and microRNA-1205 (miR-1205). Cell proliferation was detected by Cell counting Kit-8 (CCK-8) and colony formation assays. Flow cytometry was used for determining cell cycle and cell apoptosis. Cell apoptosis was also assessed by caspase3 and caspase9 activities. Cell migration and invasion were examined using scratch assay and transwell assay. The interaction between circ_0082182 and miRNA was validated by the dual-luciferase reporter and biotinylated RNA pull-down assays. Wnt/β-catenin pathway and epithelial-mesenchymal transition (EMT)-associated proteins were quantified by Western blot. Xenograft model was established for the research of circ_0082182 in vivo.

RESULTS

Circ_0082182 was upregulated in CRC and could predict the poor prognosis of CRC patients. Functionally, circ_0082182 promoted CRC cell proliferation, cell cycle progression, and metastasis while inhibited apoptosis. Subsequently, circ_0082182 was shown to act as the sponges of miR-411 and miR-1205. MiR-411 and miR-1205 were identified as tumor inhibitors in CRC. Furthermore, circ_0082182 promoted the CRC progression via sponging miR-411 and miR-1205. Moreover, circ_0082182 facilitated the Wnt/β-catenin pathway and EMT process by targeting miR-411 and miR-1205. In vivo, circ_0082182 accelerated the CRC tumorigenesis and EMT process by activating the Wnt/β-catenin pathway by downregulating the expression of miR-411 or miR-1205.

CONCLUSION

This study showed that circ_0082182 functioned as an oncogene in the developing process of CRC by sponging miR-411 or miR-1205 to activate the Wnt/β-catenin pathway. Circ_0082182 might be a molecular target in the diagnosis and treatment of CRC.

Circ_0035483 Functions as a Tumor Promoter in Renal Cell Carcinoma via the miR-31-5p-Mediated HMGA1 Upregulation

Background

Renal cell carcinoma (RCC) that originates from the proximal renal tubules is the most common cancer of the human kidney. Increasing circRNA/miRNA/mRNA networks have been found in RCC regulation. This study will explore the regulatory relation of circular RNA (circRNA) circ_0035483, microRNA-31-5p (miR-31-5p) and high mobility group A1 (HMGA1).

Methods

The levels of circ_0035483, miR-31-5p and HMGA1 were measured by real-time polymerase chain reaction (qRT-PCR) or Western blot. Cell proliferation was determined using Cell Counting Kit-8 (CCK-8) and colony formation assays. Cell migration and invasion were assessed by transwell assay. HMGA1 and epithelial–mesenchymal transition (EMT)-related protein levels were quantified using Western blot. Glycolytic metabolism was evaluated by glucose consumption and lactate production. The interaction between targets was confirmed via dual-luciferase reporter, RNA immunoprecipitation (RIP) and RNA pull-down assays. In vivo experiment was performed through the establishment of xenograft models in mice.

Results

Circ_0035483 expression was upregulated in RCC tissues and cells. The inhibitory effects on RCC cell proliferation, migration, invasion, EMT and glycolysis were induced after circ_0035483 was downregulated. MiR-31-5p was identified as a target of circ_0035483 and miR-31-5p upregulation was related to the function of circ_0035483 knockdown in RCC cells. Additionally, miR-31-5p targeted HMGA1 and inhibited the malignant behaviors of RCC cells by negatively regulating HMGA1. Moreover, HMGA1 expression was regulated by circ_0035483 via targeting miR-31-5p. Circ_0035483 also affected tumor growth in vivo by relying on the miR-31-5p/HMGA1 axis.

Conclusion

These findings clarified that the tumor-promoting function of circ_0035483 in RCC was partly achieved by regulating the miR-31-5p/HMGA1 axis.

Heterogeneous miRNA-mRNA Regulatory Networks of Visceral and Subcutaneous Adipose Tissue in the Relationship Between Obesity and Renal Clear Cell Carcinoma

BACKGROUND

Clear cell renal cell carcinoma (ccRCC) is one of the most lethal urologic cancer. Associations of both visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) with ccRCC have been reported, and underlying mechanisms of VAT perhaps distinguished from SAT, considering their different structures and functions. We performed this study to disclose different miRNA-mRNA networks of obesity-related ccRCC in VAT and SAT using datasets from Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA); and find out different RNAs correlated with the prognosis of ccRCC in VAT and SAT.

METHODS

We screened out different expressed (DE) mRNAs and miRNAs of obesity, in both VAT and SAT from GEO datasets, and constructed miRNA-mRNA networks of obesity-related ccRCC. To evaluate the sensitivity and specificity of RNAs in networks of obesity-related ccRCC in both VAT and SAT, Receiver Operating Characteristic (ROC) analyses were conducted using TCGA datasets. Spearman correlation analyses were then performed to find out RNA pairs with inverse correlations. We also performed Cox regression analyses to estimate the association of all DE RNAs of obesity with the overall survival.

RESULTS

136 and 185 DE mRNAs of obesity in VAT and SAT were found out. Combined with selected DE miRNAs, miRNA-mRNA networks of obesity-related ccRCC were constructed. By performing ROC analyses, RNAs with same trend as shown in networks and statistically significant ORs were selected to be paired. Three pairs were finally remained in Spearman correlation analyses, including hsa-miR-182&ATP2B2, hsa-miR-532&CDH2 in VAT, and hsa-miR-425&TFAP2B in SAT. Multivariable Cox regression analyses showed that several RNAs with statistically significant adjusted HRs remained consistent trends as shown in DE analyses of obesity. Risk score analyses using selected RNAs showed that the overall survival time of patients in the low-risk group was significantly longer than that in the high-risk group regardless of risk score models.

CONCLUSIONS

We found out different miRNA-mRNA regulatory networks of obesity-related ccRCC for both VAT and SAT; and several DE RNAs of obesity-related ccRCC were found to remain consistent performance in terms of ccRCC prognosis. Our findings could provide valuable evidence on the targeted therapy of obesity-related ccRCC.

Circ_101341 Deteriorates the Progression of Clear Cell Renal Cell Carcinoma Through the miR- 411/EGLN3 Axis

Background

Clear cell renal cell carcinoma (ccRCC) is one of the main subtypes of renal cell carcinoma, with intense aggressiveness. The involvement of circular RNAs (circRNAs) in human cancers attracts much concern. The intention of this study was to investigate the expression of circ_101341 and explore its function in ccRCC.

Materials and Methods

The expression of circ_101341, miR-411 and Egl nine homolog 3 (EGLN3) was measured using quantitative real-time polymerase chain reaction (qRT-PCR). Cell proliferation was assessed by cell counting kit-8 (CCK-8) assay and colony formation assay. Cell migration and invasion were monitored by transwell assay. Xenograft model was established to explore the role of circ_101341 in vivo. The protein levels of E-cadherin (E-cad), N-cadherin (N-cad), matrix metalloprotein-9 (MMP9) and EGLN3 were detected by Western blot. Bioinformatic analysis was conducted using Circinteractome and starBase. The targeted relationship was verified using dual-luciferase reporter assay, RNA-binding protein immunoprecipitation (RIP) assay and RNA pull-down assay.

Results

The expression of circ_101341 was elevated in ccRCC tissues and cells. Functionally, circ_101341 knockdown depleted proliferation, migration and invasion of ccRCC cells in vitro and restricted tumor growth in vivo. Circ_101341 directly targeted miR-411, and miR-411 inhibition revised the inhibitory effects of circ_101341 knockdown on proliferation, migration and invasion in ccRCC cells. Moreover, miR-411 directly bound to EGLN3, and EGLN3 overexpression also rescued the effects of circ_101341 knockdown.

Conclusion

Circ_101341 functioned as a tumor promoter to strengthen proliferation, migration and invasion by regulating EGLN3 via sponging miR-411, indicating that circ_101341 was a potential diagnostic and therapeutic biomarker of ccRCC.

Upregulated circPDK1 Promotes RCC Cell Migration and Invasion by Regulating the miR-377-3P-NOTCH1 Axis in Renal Cell Carcinoma

Background

Circular RNAs (circRNAs) are novel clusters of endogenous noncoding RNAs (ncRNAs) that are involved in the regulation of multiple biological processes in diverse types of cancers. However, the roles and precise mechanisms of circRNAs in renal cell carcinoma (RCC) occurrence and progression have not been clearly elucidated.

Methods

We identified the aberrantly expressed circRNAs in RCC by high-throughput RNA-seq assay and used qRT-PCR to test the expression level of circRNAs in RCC tissues. Loss-of-function experiments were executed to detect the biological roles of circPDK1 in the RCC cells both in vivo and in vitro. RNA Fish, luciferase reporter assays and Western blotting were used to explore the molecular mechanism of circPDK1 function. All data were expressed as the means ± standard error of the mean (SEM). Student’s t-test, one-way ANOVA, Cox regression, an LSD-t-test, Pearson’s chi-squared test, a Log-rank test, and linear regression analyses were used to evaluate the group differences. P < 0.05 was considered significant.

Results

CircPDK1 was overexpressed in RCC tissues and positively associated with patient tumor metastasis and renal cell invasion. The in vivo functional assays also revealed that circPDK1 drove RCC xenograft metastasis. CircPDK1 was mainly located in the cytoplasm, serving as a sponge of miR-377-3P to regulate RCC invasion and metastasis through NOTCH1 (Notch Homolog 1). Ectopic express of NOTCH1 in RCC cell lines will block the metastasis inhibition effect after circPDK1 knockdown.

Conclusion

CircPDK1 is aberrantly expressed in RCC and promotes the metastasis of RCC cells mainly through sponging miR-377-3P and reducing its negative regulation of NOTCH1. Thus, circPDK1 may act as a therapeutic target and biomarker for RCC.

Circular RNAs in renal cell carcinoma: implications for tumorigenesis, diagnosis, and therapy

Renal cell carcinoma (RCC) is the most common malignant kidney tumor and has a high incidence rate. Circular RNAs (circRNAs) are noncoding RNAs with widespread distribution and diverse cellular functions. They are highly stable and have organ- and tissue-specific expression patterns. CircRNAs have essential functions as microRNA sponges, RNA-binding protein- and transcriptional regulators, and protein translation templates. Recent reports have shown that circRNAs are abnormally expressed in RCC and act as important regulators of RCC carcinogenesis and progression. Moreover, circRNAs have emerged as potential biomarkers for RCC diagnosis and prognosis and targets for developing new treatments. However, further studies are needed to better understand the functions of circRNAs in RCC. In this review, we summarize and discuss the recent research progress on RCC-associated circRNAs, with a focus on their potential for RCC diagnosis and targeted therapy.

Comprehensive analysis of competitive endogenous RNAs network reveals potential prognostic lncRNAs in gastric cancer

Long non-coding RNAs (lncRNAs) are key regulators of a range of human diseases, including various cancers, with multiple previous studies having explored lncRNA dysregulation in the context of gastric cancer (GC). The present study sought to expand upon these previous results by downloading lncRNA, mRNA, and microRNA (miRNA) expression profiles derived from 180 GC tissues and 24 normal control tissues within the Cancer Genome Atlas (TCGA) database. These datasets were then interrogated to identify GC-related differentially expressed (DE) RNAs (|fold change| ≥ 2, FDR< 0.01), leading to the identification of 1946 DE lncRNAs, 123 DE miRNAs, and 3159 DE mRNAs. These results were then used to generate a putative GC-related competitive endogenous RNA (ceRNA) network composed of 131 lncRNAs, 9 miRNAs, and 78 mRNAs. Subsequent survival analyses based upon this network revealed 17 of these lncRNAs to be significantly associated with GC patient survival (P < 0.05). Further multivariable Cox regression and lasso analyses allowed for the construction of an 8-lncRNA risk score that was able to effectively predict GC patient survival with good discriminative ability. The Kaplan-Meier Plotter database further confirmed that network hub genes that were related to these 8 lncRNAs were associated with GC patient prognosis (P < 0.05). As the ceRNA network in the present study was constructed with a focus on both disease stage and differential gene expression, it represents a key resource that will offer valuable insights into the mechanistic roles of ceRNA pathways in GC development and progression.