Construction and analysis of circular RNA molecular regulatory networks in clear cell renal cell carcinoma

Six MicroRNA Prognostic Models for Overall Survival of Lung Adenocarcinoma

Objective

The purpose of this study is to screen for microRNAs (miRNAs) associated with the prognosis of lung adenocarcinoma (LUAD) and to explore its prognosis and effects on the tumor microenvironment in patients with LUAD.

Methods

Gene expression data, miRNA expression data, and clinical data for two different databases, TCGA-LUAD and CPTAC-3 LUAD, were downloaded from the GDC database. The miRNA prognosis of LUAD was filtered by the Cox proportional hazard model and the Least Absolute Shrinkage and Selection Operator (LASSO) regression model. The performance of the model was validated by time-dependent receiver operating characteristics (ROC) curves. Possible biological processes associated with the miRNAs target gene were analyzed through Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Finally, the prognostic model was scored by risk, divided into high- and low-risk groups by median, and the differences in the immersion level of 21 immune cells in the high- and low-risk groups were assessed. To gain a deeper understanding of the underlying mechanism behind the model, the two most important miRNAs in the model, miR-195-3p and miR-5571-5p, were selected for HPA database validation and ceRNA network construction.

Results

Of the 209 variance expressions identified in the screening analysis, 145 were upregulated and 64 were downregulated by miRNAs. The prognostic models of six miRNA genes were obtained: miR-195-3p, miR-5571-5p, miR-584-3p, miR-494-3p, miR-4664-3p, and miR-1293. These six genes were significantly associated with survival rates in LUAD patients. In particular, miR-1293, miR-195-3p, and miR-5571-5p are highly correlated with OS. The higher expression of miR-195-3p and miR-5571-5p, the better survival of LUAD OS is, and these two miRNA expressions contribute the most to the model. Finally, after sorting the risk scores calculated from low to high using the prognostic model, the patients with higher scores had shorter survival time and higher frequency of death, and there were significant differences in the immersion levels of 21 immune cells in the high- and low-risk groups. ceRNA network analysis found that TM9SF3 was regulated by miR-195-3p and was highly expressed in the tissues of LUAD patients, and the prognosis of the patients was poor.

Conclusions

miR-195-3p, miR-5571-5p, miR-584-3p, miR-494-3p, miR-4664-3p, and miR-1293 may be used as new biomarkers for prognosis prediction of LUAD. Our results also identified a lncRNA MEG3/miR-195-3p/RAB1A/TM9SF3 regulatory axis, which may also play an important role in the progression of LUAD. Further study needs to be conducted to verify this result.

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.

Propofol Disrupts Clear Cell Renal Cell Carcinoma Tumorigenesis by Regulating circFBXW7/miR-942 Axis

<b><i>Background:</i></b> Propofol is a commonly used intravenous anesthetic and has been found to perform anticancer effects in many cancers. However, the effects and mechanisms of propofol in clear cell renal cell carcinoma (ccRCC) remain largely undefined. <b><i>Methods:</i></b> The expression of circular RNA FBXW7 (circFBXW7) and miR-942 was detected by qRT-PCR. Cell proliferation, apoptosis, migration, and invasion capacities were analyzed using cell counting kit-8, colony formation, flow cytometry, and transwell assays, respectively. Western blot was used to detect the expression levels of PCNA, Cleaved-caspase 3 and MMP protein. The bindings between miR-942 and circFBXW7 were verified using RNA pull-down, dual-luciferase reporter, and RIP assays. Xenograft tumor analysis was employed to detect tumorigenesis in vivo. <b><i>Results:</i></b> Propofol alleviated cell proliferation, migration, invasion, and induced apoptosis in vitro and impeded tumor growth in vivo in ccRCC. Propofol elevated the level of circFBXW7, which knockdown reversed the anticancer effects of propofol on ccRCC cell tumorigenesis. CircFBXW7 directly bound to miR-942, and suppressed ccRCC cell malignant biological behaviors via targeting miR-942. Besides that, propofol decreased miR-942 expression, and miR-942 overexpression attenuated the effects of propofol on ccRCC cells. Moreover, propofol could regulate miR-942 expression through circFBXW7. <b><i>Conclusion:</i></b> Propofol suppressed the growth, migration, and invasion of ccRCC cells by regulating circFBXW7/miR-942 axis, suggesting a potential therapeutic strategy for the intervention of human ccRCC development.

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.

Investigating Urinary Circular RNA Biomarkers for Improved Detection of Renal Cell Carcinoma

Renal cell carcinomas (RCC) are usually asymptomatic until late stages, posing several challenges for early detection of malignant disease. Non-invasive liquid biopsy biomarkers are emerging as an important diagnostic tool which could aid with routine screening of RCCs. Circular RNAs (circRNAs) are novel non-coding RNAs that play diverse roles in carcinogenesis. They are promising biomarkers due to their stability and ease of detection in small quantities from non-invasive sources such as urine. In this study, we analyzed the expression of various circRNAs that were previously identified in RCC tumors (circEGLN3, circABCB10, circSOD2 and circACAD11) in urinary sediment samples from non-neoplastic controls, patients with benign renal tumors, and clear cell RCC (ccRCC) patients. We observed significantly reduced levels of circEGLN3 and circSOD2 in urine from ccRCC patients compared to healthy controls. We also assessed the linear variant of EGLN3 and found differential expression between patients with benign tumors compared to ccRCC patients. These findings highlight the potential of circRNA markers as non-invasive diagnostic tools to detect malignant RCC.

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.

Circ_RPL23A acts as a miR-1233 sponge to suppress the progression of clear cell renal cell carcinoma by promoting ACAT2

Clear cell renal cell carcinoma (ccRCC) is a prevalent urological carcinoma with high metastatic risk. Circular RNAs (circRNAs) have been identified as effective diagnostic and therapeutic biomarkers for ccRCC. This research aims to disclose the effect and regulatory mechanism of circRNA ribosomal protein L23a (circ_RPL23A) in ccRCC. We performed quantitative real-time polymerase chain reaction (qRT-PCR) to examine circ_RPL23A, microRNA-1233 (miR-1233) and acetyl-coenzyme A acetyltransferase 2 (ACAT2). Cell cycle progression, apoptosis, cell viability, invasion and migration, which were respectively conducted by using flow cytometry, 3-(4, 5-dimethylthiazol-2-y1)-2, 5-diphenyl tetrazolium bromide (MTT), transwell assays. The levels of ACAT2 protein and cell cycle proteins, proliferation-associated protein, and epithelial-mesenchymal transition (EMT) associated proteins were measured by western blot. Target relationship was analyzed via dual-luciferase reporter assay and RNA pull down assay. The animal model was used to study how circ_RPL23A affects in vivo. Circ_RPL23A was lower expressed in ccRCC tissues and cells. The elevated circ_RPL23A suppressed cell cycle progression, proliferation, migration and invasion but promoted apoptosis in ccRCC cells. MiR-1233 was a target of circ_RPL23A and direct targeted to ACAT2. Besides, circ_RPL23A exerted its anti-tumor effect by sponging miR-1233, and then relieved the inhibition effect of miR-1233 on ACAT2. Overexpression of circ_RPL23A also curbed ccRCC tumor growth in vivo. Circ_RPL23A inhibited ccRCC progression by upregulating ACAT2 expression by competitively binding miR-1233, which might provide an in-depth cognition for ccRCC pathogenesis and circ_RPL23A might be a promising biomarker in ccRCC diagnosis and treatment.

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.

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.

CircHIPK3 Promotes Clear Cell Renal Cell Carcinoma (ccRCC) Cells Proliferation and Metastasis via Altering of miR-508-3p/CXCL13 Signal

Introduction

Accumulating evidence has demonstrated that circular RNAs (circRNAs) play a key role in the tumorigenesis of various types of cancers, including clear cell renal cell carcinoma (ccRCC).

Materials and Methods

Reverse transcription-quantitative polymerase chain reaction was used to detect the expression of circRNA homeodomain interacting protein kinase 3 (circHIPK3) and microRNAs (miRNAs), including miR-508-3p. The clinical measurement of circHIPK3 was evaluated by Kaplan-Meier survival analysis and receiver operating characteristic analysis. Cell Counting Kit-8 and Transwell chamber assays were performed to determine the changes in the proliferative and metastatic ability of A498 and 786-O cells. C-X-C motif chemokine ligand 13 (CXCL13) protein expression was detected by Western blot analysis. The targeted binding effect between miR-508-3p and circHIPK3 or CXCL13 was confirmed by constructed luciferase and RNA immunoprecipitation (RIP) assays, respectively. Fluorescence in situ hybridization (FISH) assay was used to measure the subcellular localization of circHIPK3 and miR-508-3p.

Results

It was found that circHIPK3 was markedly upregulated in ccRCC tissue and cell lines, and circHIPK3-upregulation was closely correlated with poor clinicopathological features in patients with ccRCC. It was found that both miR-508-3p and circHIPK3 were localized in the cytoplasm of ccRCC cells. The up- and downregulation of circHIPK3 positively regulated ccRCC cell proliferation and metastasis, and this regulatory effect was reversed by miR-508-3p. Through luciferase and RIP assays, it was confirmed that circHIPK3 could interacted with miR-508-3p. Furthermore, it was revealed that CXCL13, which was negatively correlated with miR-508-3p, was upregulated in ccRCC. It was also shown that CXCL13 was a downstream target of miR-508-3p. miR-508-3p suppressed ccRCC cell proliferation and metastasis by targeting CXCL13. Lastly, it was demonstrated that circHIPK3 promoted CXCL13 to facilitate ccRCC cell proliferation and metastasis by decoying miR-508-3p.

Conclusion

In brief, the results of the present study showed that circHIPK3 promoted ccRCC cell proliferation and metastasis by altering miR-5083p/CXCL13 signaling. The present findings might provide a novel target for the molecular treatment of ccRCC.

Hsa_circ_0085576 promotes clear cell renal cell carcinoma tumorigenesis and metastasis through the miR-498/YAP1 axis

There is emerging evidence that circular RNAs (circRNAs) act as important regulators in various cancers. It is less clear, however, what role circRNA plays in the tumorigenesis and metastasis of clear cell renal cell carcinoma (ccRCC). In this study, using bioinformatics analysis and a series of experimental analysis, we characterized a novel circRNA, hsa_circ_0085576 was up-regulated in ccRCC tissues and cell lines. High hsa_circ_0085576 expression was significantly correlated with tumor size, clinical stage, and metastasis status and poorer survival. Knockdown of hsa_circ_0085576 notably inhibited cell proliferation, migration, invasion, whereas enhanced cell apoptosis of ccRCC cells, in vitro. In contrast, overexpression of hsa_circ_0085576 had the opposite effects. Moreover, hsa_circ_0085576 silencing significantly suppressed tumor growth and metastasis, whereas overexpression of hsa_circ_0085576 had the opposite effects, in vivo, Our results further showed that hsa_circ_0085576 acted as a competitive endogenous RNAs to interact with microRNA-498, to attenuate its repressive effect on target gene Yes-associated protein 1 (YAP1). Finally, functional studies revealed that inhibition of hsa_circ_0085576 suppressed cell growth and metastasis by regulating miR-498/YAP1 signaling, in ccRCC cells. Based on these findings, hsa_circ_0085576 may represent a valuable prognostic biomarker and a potential therapeutic target to curb the tumorigenesis and metastasis of ccRCC.

Circular RNA in renal diseases

Circular RNA (circRNA) is a newly described type of non-coding RNA. Active research is greatly enriching the current understanding of the expression and role of circRNA, and a large amount of evidence has implicated circRNA in the pathogenesis of certain renal diseases, such as renal cell carcinoma, acute kidney injury, diabetic nephropathy and lupus nephritis. Studies have found evidence that circRNAs regulate programmed cell death, invasion, and metastasis and serve as biomarkers in renal diseases. Recently, circRNAs were identified in exosomes secreted by the kidneys. Nevertheless, the function of circRNA in renal diseases remains ambiguous. Given that circRNAs are regulators of gene expression, they may be involved in the pathology of multiple renal diseases. Additionally, emerging evidence is showing that circulating circRNAs may serve as novel biomarkers for renal disease. In this review, we have summarized the identification, biogenesis, degradation, and functions of circRNA and have evaluated the roles of circRNA in renal diseases.

Circ-APBB1IP as a Prognostic Biomarker Promotes Clear Cell Renal Cell Carcinoma Progression Through The ERK1/2 Signaling Pathway

Circular RNA (circRNA), a member of non-coding RNA, plays an essential regulatory role in many human physiological and pathological processes; however, its role in clear cell renal cell carcinoma (ccRCC) still unclear. This study aims to investigate the effect and mechanisms of circRNA on ccRCC progression. A human circRNA microarray was used to discover differential expression circRNA, and a quantitative real-time polymerase chain reaction (qRT-PCR) was performed to verify the expression of circRNA. The function and mechanism of circRNA were explored by cell transfection, cell counting kit-8, fluorescein isothiocyanate (FITC) Annexin V apoptosis detection, wound healing, transwell, and western blot. The result indicated that circ-APBB1IP was significantly up-regulated in ccRCC. In vitro, knockdown of circ-APBB1IP by siRNA suppressed the proliferation, migration, and invasion and increased the apoptosis of ccRCC cells. Further study found that knockdown of circ-APBB1IP up-regulated protein expression of cleaved caspase-3, cleaved caspase-7, cleaved caspase-8, cleaved caspase-9, Bax, Bad, Bak, E-cadherin and down-regulated expression of Bcl-2, N-cadherin, MMP-2, MMP-9, p-ERK1/2. Our result indicates that circ-APBB1IP has a vital function in ccRCC tumorigenesis. These findings suggest that circ-APBB1IP represents a novel potential biomarker and therapeutic target of ccRCC.