Hsa_circ_0046264 up-regulated BRCA2 to suppress lung cancer through targeting hsa-miR-1245

The multifaceted roles of circular RNAs in cancer hallmarks: From mechanisms to clinical implications

Circular RNAs (circRNAs) represent a distinct class of covalently closed RNA species lacking conventional 5' to 3' polarity. Derived predominantly from pre-mRNA transcripts of protein-coding genes, circRNAs arise through back-splicing events of exon-exon or exon-intron junctions. They exhibit tissue- and cell-specific expression patterns and play crucial roles in regulating fundamental cellular processes such as cell cycle dynamics, proliferation, apoptosis, and differentiation. CircRNAs modulate gene expression through a plethora of mechanisms at epigenetic, transcriptional, and post-transcriptional levels, and some can even undergo translation into functional proteins. Recently, aberrant expression of circRNAs has emerged as a significant molecular aberration within the intricate regulatory networks governing hallmarks of cancer. The tumor-specific expression patterns and remarkable stability of circRNAs have profound implications for cancer diagnosis, prognosis, and therapy. This review comprehensively explores the multifaceted roles of circRNAs across cancer hallmarks in various tumor types, underscoring their growing significance in cancer diagnosis and therapeutic interventions. It also details strategies for leveraging circRNA-based therapies and discusses the challenges in using circRNAs for cancer management, emphasizing the need for further research to overcome these obstacles.

Circular RNAs in lung cancer: implications for preventing therapeutic resistance

LC is one of the most common malignant tumours that often presents with no distinct symptoms in the early stages, leading to late diagnoses when patients are at an advanced stage and no longer suitable for surgical treatment. Although adjuvant treatments are available, patients frequently develop tolerance to these treatments over time, resulting in poor prognoses for patients with advanced LC. Recently, circular RNAs (circRNAs), a type of non-coding RNA, have gained significant attention in LC research. Owing to their unique circular structure, circRNAs are highly stable within cells. This review systematically summarises the expression, characteristics, biological functions, and molecular regulatory mechanisms of circRNAs involved in therapy resistance as well as the potential applications in early diagnosis and gene targeting therapy in LC.

The role of circular RNAs (circRNAs) as a prognostic factor in lung cancer: a meta-analysis

BACKGROUND

Lung cancer is a leading cause of cancer-related death worldwide. Among various histological types of lung cancer, majority are non-small cell lung cancer (NSCLC) which account for > 80%. Circular RNAs (circRNAs) are widely expressed in various cancers including lung cancer and implicated in tumourigenesis and cancer progression. This study aimed to systematically evaluate the prognostic values of circRNAs in lung cancer.

METHODS

A systematic literature search was done in PubMed, Embase, and MEDLINE databases to select the eligible studies which reported the association between the expression of circRNAs and overall survival (OS) or disease-free survival (DFS) in histopathologically diagnosed lung cancer patients. The pooled hazard ratio (HR) and 95% confidence interval (CI) were assessed to determine the prognostic significance of circRNAs.

RESULTS

A total of 43 studies were eligible for this meta-analysis (MA). 39 different types of circRNAs were reported: 28 showing upregulating and 11 showing downregulating action in lung cancer. High expression of circRNAs with upregulating action in lung cancer was associated with worse prognosis and poor OS (HR 1.93, 95% CI [1.61-2.33], p < 0.00001). High expression of circRNAs with downregulating action in lung cancer was associated with favorable OS and prognosis (HR 0.73, 95% CI [0.58-0.94], p = 0.01). However, there was no statistically significant association between high and low expression of both upregulating and downregulating circRNAs and DFS (HR 1.44, 95% CI [0.92-2.24], p = 0.11).

CONCLUSIONS

This MA confirmed the pivotal role of circRNAs as important prognostic biomarkers for lung cancer, especially NSCLC. High expression of upregulating circRNAs is associated with poor prognosis; however, high expression of downregulating circRNAs is associated with favorable prognosis. Therefore, downregulatory action of circRNAs should be considered a promising treatment in the management of lung cancer, especially NSCLC.

Osteosarcoma in a ceRNET perspective

Osteosarcoma (OS) is the most prevalent and fatal type of bone tumor. It is characterized by great heterogeneity of genomic aberrations, mutated genes, and cell types contribution, making therapy and patients management particularly challenging. A unifying picture of molecular mechanisms underlying the disease could help to transform those challenges into opportunities.This review deeply explores the occurrence in OS of large-scale RNA regulatory networks, denominated "competing endogenous RNA network" (ceRNET), wherein different RNA biotypes, such as long non-coding RNAs, circular RNAs and mRNAs can functionally interact each other by competitively binding to shared microRNAs. Here, we discuss how the unbalancing of any network component can derail the entire circuit, driving OS onset and progression by impacting on cell proliferation, migration, invasion, tumor growth and metastasis, and even chemotherapeutic resistance, as distilled from many studies. Intriguingly, the aberrant expression of the networks components in OS cells can be triggered also by the surroundings, through cytokines and vesicles, with their bioactive cargo of proteins and non-coding RNAs, highlighting the relevance of tumor microenvironment. A comprehensive picture of RNA regulatory networks underlying OS could pave the way for the development of innovative RNA-targeted and RNA-based therapies and new diagnostic tools, also in the perspective of precision oncology.

The functional significance of circRNA/miRNA/mRNA interactions as a regulatory network in lung cancer biology

Lung cancer, the leading cause of cancer-related deaths, presents significant challenges to patients due to its poor prognosis. Recent research has increasingly implicated circular RNAs in the development and progression of lung cancer. These circular RNAs have been found to impact various aspects of tumor behavior, including proliferation, metastasis, cell cycle regulation, apoptosis, cancer stem cells, therapy response, and the tumor microenvironment. One of the key mechanisms by which circular RNAs exert their influence is through their ability to act as miRNA sponges, sequestering microRNAs and preventing them from targeting other RNA molecules. Accumulating evidence suggests that circular RNAs can function as competing endogenous RNAs, affecting the expression of target mRNAs by sequestering microRNAs. Dysregulation of competing endogenous RNAs networks involving circular RNAs, microRNAs, and mRNAs leads to the aberrant expression of oncogenes and tumor suppressors involved in lung cancer pathogenesis. Understanding the dynamic interplay and molecular mechanisms among circular RNAs, microRNAs, and mRNAs holds great promise for advancing early diagnosis, personalized therapeutic interventions, and improved patient outcomes in lung cancer. Therefore, this study aims to provide an in-depth exploration of the executive roles of circular RNAs/microRNAs/ mRNAs interactions in lung cancer pathogenesis and their potential utility for diagnosing lung cancer, predicting patient prognosis, and guiding targeted therapies. By offering a comprehensive overview of the dysregulation of the axes as driving factors in lung cancer, we aim to pave the way for their translation into clinical practice in the future.

Deregulation of miR-1245b-5p and miR-92a-3p and their potential target gene, GATA3, in epithelial-mesenchymal transition pathway in breast cancer

BACKGROUND

MicroRNAs (miRNAs) are small molecules that have prominent roles in tumor development and metastasis and can be used for diagnostic and therapeutic purposes. This study evaluated the expression of miR-92a-3p and miR-1245b-5p and their potential target gene, GATA3 in patients with breast cancer (BC).

MATERIALS AND METHODS

In the search for BC-related microRNAs, miR-124b-5p and miR-92a-3p were selected using Medline through PubMed, miR2disease, miRcancer and miRTarBase. Moreover, target gene GATA3 and their possible interaction in the regulating epithelial-mesenchymal transition (EMT) and invasion was evaluated using in silico tools including miRTarBase, TargetScan, STRING-db, and Cytoscape. The expression level of miR-92a-3p, miR1245b-5p, and GATA3 were assessed on extracted RNAs of tumor and nontumor tissues from 36 patients with BC using qPCR. Additionally, clinical-pathologic characteristics, such as tumor grade, tumor stage, lymph node were taken into consideration and the diagnostic power of these miRNAs and GATA3 was evaluated using the ROC curve analysis.

RESULTS

In silico evaluation of miR-92a-3p and miR-1245b-5p supports their potential association with EMT and invasion signaling pathways in BC pathogenesis. Comparing tumor tissues to nontumor tissues, we found a significant downregulation of miR-1245b-5p and miR-92a-3p and upregulation of GATA3. Patients with BC who had decreased miR-92a-3p expression also had higher rates of advanced stage/grade and ER expression, whereas decreased miR-1245b-5p expression was only linked to ER expression and was not associated with lymph node metastasis. The AUC of miR-1245b-5p, miR-92a-3p, and GATA3 using ROC curve was determined 0.6449 (p = .0239), 0.5980 (p = .1526), and 0.7415 (p < .0001), respectively, which showed a significant diagnostic accuracy of miR-1245b-5p and GATA3 between the BC patients and healthy individuals.

CONCLUSION

MiR-1245b-5p, miR-92a-3p, and GATA3 gene contribute to BC pathogenesis and they may be having potential regulatory roles in signaling pathways involved in invasion and EMT pathways in BC pathogenesis, as a result of these findings. More research is needed to determine the regulatory mechanisms that they control.

The Tumorigenic Role of Circular RNA-MicroRNA Axis in Cancer

Circular RNAs (circRNAs) are a class of endogenous RNAs that control gene expression at the transcriptional and post-transcriptional levels. Recent studies have increasingly demonstrated that circRNAs act as novel diagnostic biomarkers and promising therapeutic targets for numerous cancer types by interacting with other non-coding RNAs such as microRNAs (miRNAs). The miRNAs are presented as crucial risk factors and regulatory elements in cancer by regulating the expression of their target genes. Some miRNAs are derived from transposable elements (MDTEs) that can transfer their location to another region of the genome. Genetic interactions between miRNAs and circular RNAs can form complex regulatory networks with various carcinogenic processes that play critical roles in tumorigenesis and cancer progression. This review focuses on the biological regulation of the correlative axis among circular RNAs, miRNAs, and their target genes in various cancer types and suggests the biological importance of MDTEs interacting with oncogenic or tumor-suppressive circRNAs in tumor progression.

Hsa_circ_0000520 Promotes Non-Small Cell Lung Cancer Progression through the miR-1258/AKT3 Axis

Background

There are several previous studies suggesting that circular RNAs (circRNAs) are involved in tumorigenesis of non-small cell lung cancer (NSCLC). Nevertheless, the role of circRNA_0000520 (circ_0000520) in this disease has not yet been studied.

Methods

circ_0000520, microRNA (miR)-1258, and AKT serine/threonine kinase 3 (AKT3) mRNA expression levels were detected by qPCR. CCK-8, EdU, and Transwell assays were utilized to detect NSCLC cells' malignant biological behaviors. The targeted relationship between miR-1258 and AKT3 3'-UTR or circ_0000520 was verified through the dual-luciferase reporter gene assay. Western blotting was utilized to measure the AKT3 expression after circ_0000520 and miR-1258 were selectively regulated.

Results

circ_0000520 was upregulated in NSCLC. Highly expressed circ_0000520 is linked to the NSCLC patient's advanced TNM stage and lymph node metastasis. circ_0000520 overexpression facilitated NSCLC cell growth, migration, and invasion. miR-1258 was identified as the downstream target of circ_0000520. miR-1258 overexpression weakened the effect of circ_0000520 overexpression on NSCLC cells. miR-1258 targeted and inhibited AKT3. circ_0000520 positively regulated the AKT3 expression in NSCLC cells by sponging miR-1258.

Conclusion

circ_0000520 upregulates AKT3 by competitively binding with miR-1258 to facilitate NSCLC progression.

Circ-GSK3B up-regulates GSK3B to suppress the progression of lung adenocarcinoma

GSK3B is the mRNA form of glycogen synthase kinase 3 beta (GSK-3β), which is a critical repressor of Wnt/β-catenin signaling pathway and generally inhibited in cancer cells. Plenty of researches have disclosed that circular RNAs, namely circRNAs exert important functions in the progression of various human malignancies including lung adenocarcinoma (LUAD). Therefore, we attempted to explore whether there existed certain circRNAs that could mediate LUAD development by regulating GSK3B expression and Wnt/β-catenin pathway. In the present research, circ-GSK3B (hsa_circ_0066903) was found to be significantly down-regulated in LUAD tissues and cells and it suppressed the proliferation, migration and stemness of LUAD cells. Furthermore, it was discovered that circ-GSK3B competitively sponged miR-3681-3p and miR-3909 to elevate GSK3B expression. Circ-GSK3B could impair the binding ability of FKBP51 to GSK-3β to inhibit the phosphorylation of GSK-3β^S9, resulting in the inactivation of Wnt/β-catenin signaling. In addition, the regulatory effect of circ-GSK3B on LUAD tumorigenesis and cell progression was testified through in vitro and in vivo rescue experiments. In conclusion, circ-GSK3B suppressed LUAD development through up-regulating and activating GSK3B.

The function and clinical implication of circular RNAs in lung cancer

Lung cancer is the leading cause of cancer-related deaths worldwide. Despite the recent advent of promising new targeted therapies, lung cancer diagnostic strategies still have difficulty in identifying the disease at an early stage. Therefore, the characterizations of more sensible and specific cancer biomarkers have become an important goal for clinicians. Circular RNAs are covalently close, endogenous RNAs without 5' end caps or 3'poly (A) tails and have been characterized by high stability, abundance, and conservation as well as display cell/tissue/developmental stage-specific expressions. Numerous studies have confirmed that circRNAs act as microRNA (miRNA) sponges, RNA-binding protein, and transcriptional regulators; some circRNAs even act as translation templates that participate in multiple pathophysiological processes. Growing evidence have confirmed that circRNAs are involved in the pathogenesis of lung cancers through the regulation of proliferation and invasion, cell cycle, autophagy, apoptosis, stemness, tumor microenvironment, and chemotherapy resistance. Moreover, circRNAs have emerged as potential biomarkers for lung cancer diagnosis and prognosis and targets for developing new treatments. In this review, we will summarize recent progresses in identifying the biogenesis, biological functions, potential mechanisms, and clinical applications of these molecules for lung cancer diagnosis, prognosis, and targeted therapy.

Hsa_circRNA_0017620 regulated cell progression of non-small-cell lung cancer via miR-520a-5p/KRT5 axis

Background

CircRNA is a very important functional RNA that plays an important role in the development and metabolism of cancer. However, the study of circRNA in NSCLC has not been fully elucidated.

Methods

The expression of hsa_circ_0017620, SFMBT2, miR‐520a‐5p, and KRT5 was determined using qRT‐PCR. KRT5, Twist1, E‐cadherin, and Ki67 protein expression were measured with western blot. The positive expression rates of Ki67 and Vimentin were determined by immunohistochemistry assay. 5‐Ethynyl‐2’‐deoxyuridine (EdU), colony formation, and MTT assays were used to assess cell proliferation. Transwell migration and invasion assay were applied to determine cell migration and invasion. Dual‐luciferase reporter and RNA immunoprecipitation assays were used to verify the relationship among hsa_circ_0017620, miR‐520a‐5p, and KRT5. The animal experiment was used to ensure the effects of hsa_circ_0017620 on tumor growth in vivo.

Results

Hsa_circ_0017620 was upregulated in NSCLC cells and tissues. MiR‐520a‐5p had been verified to be a target miRNA of hsa_circ_0017620 and KRT5 had been verified to be a target mRNA of miR‐520a‐5p in NSCLC cells. Knockdown of hsa_circ_0017620 inhibited cell proliferation, migration, and invasion in NSCLC cells, which was reversed by downregulating miR‐520a‐5p or upregulating KRT5 in NSCLC. Overexpression of hsa_circ_0017620 had opposite effects in NSCLC. Moreover, hsa_circ_0017620 silencing inhibited tumor growth in vivo of NSCLC.

Conclusion

In this study, we found that hsa_circ_0017620 played an important role in NSCLC progression. Hsa_circ_0017620 regulated cell proliferation, invasion, and migration through targeting miR‐520a‐5p/KRT5 axis in NSCLC, providing a potential new target for the treatment and diagnosis of NSCLC.

Hsa_circ_0006677 regulates special AT-rich binding protein-2-mediated tumor-suppressive effect via functioning as a miR-1245a sponge in non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is still one of the most challenging malignant tumors. Deregulation of circular RNAs (circRNAs) is associated with NSCLC progression. However, the regulatory mechanism of circRNAs in NSCLC still needs to be studied. We selected a differentially expressed hsa_circ_0006677 (circ_0006677) in NSCLC through analyzing the GSE158695 and GSE112214 datasets. Expression of circ_0006677 was evaluated by real-time quantitative polymerase-chain reaction (RT-qPCR). Effects of circ_0006677 overexpression on NSCLC cell proliferation, apoptosis, migration, invasion, and stemness were determined by clonogenic, 5-ethynyl-2’-deoxyuridine (EdU), flow cytometry, transwell, and sphere formation assays. The regulatory mechanism of circ_0006677 was predicted by bioinformatics analysis and verified by dual-luciferase reporter and RIP assays. Animal experiments were carried out to validate the function of circ_0006677 in vivo. We observed the downregulation of circ_0006677 in NSCLC samples and cells. Functionally, circ_0006677 overexpression decreased xenograft tumor growth and restrained NSCLC cell proliferation, invasion, migration, stemness, and induced NSCLC cell apoptosis in vitro. Molecular mechanism experiments exhibited that circ_0006677 functioned as a miR-1245a sponge and mediated SATB2 expression through adsorbing miR-1245a. Either miR-1245a overexpression or SATB2 knockdown weakened circ_0006677 overexpression-mediated repression on proliferation, invasion, migration, and stemness. In conclusion, circ_0006677 regulated SATB2-mediated tumor-suppressive effect via acting as a miR-1245a sponge in NSCLC, providing a new mechanism for understanding the progression of NSCLC.

circPTEN suppresses colorectal cancer progression through regulating PTEN/AKT pathway

Recently, circular RNAs (circRNAs) have attracted growing attention due to their pivotal roles in the complicated cellular processes of diverse human malignancies, including colorectal cancer (CRC). Phosphatase and tensin homolog (PTEN) is known as a typical tumor-suppressing gene. Nevertheless, limited investigation on the function of circRNAs generated from PTEN has been undertaken. In this research, hsa_circ_0094343 (circPTEN) was found to display low expression in CRC tissues and cells. CircPTEN is characterized with high stability due to its circular structure. Upregulation of circPTEN suppressed CRC cell proliferation, migration, and invasion but facilitated apoptosis. Data from mechanism assays revealed that circPTEN could elevate PTEN expression through sequestering microRNA-4470 (miR-4470) in CRC cells. Further, circPTEN was validated to inhibit K63-linked ubiquitination of protein kinase B (AKT) and AKT phosphorylation at Thr-308 and Ser-473 by competitively binding with tumor necrosis factor (TNF)-receptor-associated factor 6 (TRAF6). Moreover, the results of rescue assays indicated that the suppressive effect of circPTEN on CRC progression could be totally reversed by overexpression of insulin like growth factor 1 (IGF-1) or partially reversed by knockdown of PTEN. To conclude, circPTEN suppresses CRC progression via regulation of PTEN/AKT pathway.

Dissecting the Role of Circular RNAs in Sarcomas with Emphasis on Osteosarcomas

Circular RNAs (circRNAs) are single-stranded RNAs generated from exons back-splicing from a single pre-mRNA, forming covalently closed loop structures which lack 5'-3'-polarity or polyadenylated tail. Ongoing research depicts that circRNAs play a pivotal role in tumorigenesis, tumor progression, metastatic potential and chemoresistance by regulating transcription, microRNA (miRNA) sponging, RNA-binding protein interactions, alternative splicing and to a lesser degree, protein coding. Sarcomas are rare malignant tumors stemming from mesenchymal cells. Due to their clinically insidious onset, they often present at advanced stage and their treatment may require aggressive chemotherapeutic or surgical options. This review is mainly focused on the regulatory functions of circRNAs on osteosarcoma progression and their potential role as biomarkers, an area which has prompted lately extensive research. The attributed oncogenic role of circRNAs on other mesenchymal tumors such as Kaposi Sarcoma (KS), Rhabdomyosarcoma (RMS) or Gastrointestinal Stromal Tumors (GISTs) is also described. The involvement of circRNAs on sarcoma oncogenesis and relevant emerging diagnostic, prognostic and therapeutic applications are expected to gain more research interest in the future.

Doxorubicin inhibits osteosarcoma progression by regulating circ_0000006/miR-646/ BDNF axis

Background

Osteosarcoma (OS) is the most common aggressive bone tumor in children and teenagers. Doxorubicin (DOX) is a chemotherapeutic drug for OS. This study aims to reveal the effects and underneath mechanism of DOX treatment in OS progression.

Methods

The expression of circular_0000006 (circ_0000006), microRNA-646 (miR-646) and brain-derived neurotrophic factor (BDNF) was detected by quantitative real-time polymerase chain reaction (qRT-PCR). BDNF protein expression was determined by western blot. Cell proliferation was illustrated by cell counting kit-8 (CCK-8) and cell colony formation assays. Cell migration and invasion were revealed by transwell migration and wound-healing assays and transwell invasion assay, respectively. Cell apoptosis was demonstrated by flow cytometry analysis. The binding relationship of miR-646 and circ_0000006 or BDNF was predicted by circRNA interactome and targetscan online database, respectively, and verified by dual-luciferase reporter assay. The effects of circ_0000006 knockdown on tumor growth in vivo were manifested by in vivo tumor formation assay.

Results

Circ_0000006 expression and the mRNA and protein levels of BDNF were dramatically upregulated, and miR-646 expression was effectively downregulated in OS tissues or cells compared with control groups. Circ_0000006 expression and BDNF protein expression were lower, and miR-646 expression was higher in DOX treatment groups than in control groups in OS cells. Circ_0000006 knockdown repressed cell proliferation, migration and invasion, whereas promoted cell apoptosis under DOX treatment in OS cells; however, these effects were attenuated by miR-646 inhibitor. Additionally, circ_0000006 sponged miR-646 to bind to BDNF. Circ_0000006 silencing suppressed tumor growth in vivo.

Conclusion

Circ_0000006 knockdown promoted DOX-mediated effects on OS development by miR-646/BDNF pathway, which provided a theoretical basis in treating OS with DOX.

Circular RNA Circ_0000677 promotes cell proliferation by regulating microRNA-106b-5p/CCND1 in non-small cell lung cancer

Recently, circular RNAs (circRNAs) have become an intense focus of research and large numbers of circRNAs have been identified, awaiting functional elucidation. Thus, the present study aims to examine the regulation of circRNAs and its molecular mechanism in lung cancer growth. Here, we show that circular RNA circ_0000677 was overexpressed and correlated with poor prognosis in non‐small cell lung cancer (NSCLC) patients. Functionally, circ_0000677 knockdown markedly inhibited proliferation of NSCLC cells by observing of immunofluorescence staining of Ki67, clone formation assay, and xenograft experiments. In mechanism, circ_0000677 acted as a sponge of microRNA-106b and further regulated CCDND1 gene expression in NSCLC cells by dual luciferase activity assay and their expression examination. Taken together, these findings suggest a role for circ_0000677/miR-106b/CCND1 regulation axis in promoting NSCLC growth and progression.

Prognostic Nomogram Based on Circular RNA-Associated Competing Endogenous RNA Network for Patients with Lung Adenocarcinoma

Evidence is increasingly indicating that circular RNAs (circRNAs) are closely involved in tumorigenesis and cancer progression. However, the function and application of circRNAs in lung adenocarcinoma (LUAD) are still unknown. In this study, we constructed a circRNA-associated competitive endogenous RNA (ceRNA) network to investigate the regulatory mechanism of LUAD procession and further constructed a prognostic signature to predict overall survival for LUAD patients. Differentially expressed circRNAs (DEcircRNAs), differentially expressed miRNAs (DEmiRNAs), and differentially expressed mRNAs (DEmRNAs) were selected to construct the ceRNA network. Based on the TargetScan prediction tool and Pearson correlation coefficient, we constructed a circRNA-associated ceRNA network including 11 DEcircRNAs, 8 DEmiRNAs, and 49 DEmRNAs. GO and KEGG enrichment indicated that the ceRNA network might be involved in the regulation of GTPase activity and endothelial cell differentiation. After removing the discrete points, a PPI network containing 12 DEmRNAs was constructed. Univariate Cox regression analysis showed that three DEmRNAs were significantly associated with overall survival. Therefore, we constructed a three-gene prognostic signature for LUAD patients using the LASSO method in the TCGA-LUAD training cohort. By applying the signature, patients could be categorized into the high-risk or low-risk subgroups with significant survival differences (HR: 1.62, 95% CI: 1.12-2.35, log-rank p = 0.009). The prognostic performance was confirmed in an independent GEO cohort (GSE42127, HR: 2.59, 95% CI: 1.32-5.10, log-rank p = 0.004). Multivariate Cox regression analysis proved that the three-gene signature was an independent prognostic factor. Combining the three-gene signature with clinical characters, a nomogram was constructed. The primary and external verification C-indexes were 0.717 and 0.716, respectively. The calibration curves for the probability of 3- and 5-year OS showed significant agreement between nomogram predictions and actual observations. Our findings provided a deeper understanding of the circRNA-associated ceRNA regulatory mechanism in LUAD pathogenesis and further constructed a useful prognostic signature to guide personalized treatment of LUAD patients.

Circular RNA hsa_circ_0081343 promotes trophoblast cell migration and invasion and inhibits trophoblast apoptosis by regulating miR-210-5p/DLX3 axis

BACKGROUND

Various circular RNAs (circRNAs) are dysregulated in the placenta of fetal growth restriction (FGR) fetuses, but their roles and regulatory mechanisms have not been fully elucidated. Herein, we aimed to elucidate the role of hsa_circ_0081343 in regulating the migration, invasion, and apoptosis of human extravillous trophoblast HTR-8 cells.

METHODS

CircRNA and miRNA levels were examined by quantitative reverse transcription PCR (qRT-PCR). Overexpression plasmid constructs and siRNAs were used to overexpress and knockdown hsa_circ_0081343, respectively. Transwell assays and flow cytometry analyses were performed to evaluate the effects of hsa_circ_0081343 or miR-210-5p on migration, invasion, and apoptosis. Protein levels were analyzed by western blotting. Dual luciferase activity and anti-AGO2 RNA immunoprecipitation (RIP) assays were performed to identify the relationship between miR-210-5p and hsa_circ_0081343.

RESULTS

Hsa_circ_0081343 expression was significantly downregulated in 37 FGR placental tissues compared to healthy placental control tissues. Hsa_circ_0081343 overexpression may inhibit apoptosis by downregulating the expression of cleaved caspase 3 and caspase 9 and alleviating the migration and invasion of HTR-8 cells by inducing the expression of MMP2 and MMP9. The dual luciferase activity and anti-AGO2 RIP assay results showed that hsa_circ_0081343 binds to miR-210-5p. miR-210-5p overexpression eliminated the effect of hsa_circ_0081343 overexpression in HTR-8 cells. Finally, DLX3 was identified as a direct target of miR-210-5p.

CONCLUSIONS

hsa_circ_0081343 expression levels are significantly downregulated in FGR placental tissues. Hsa_circ_0081343 regulates the migration, invasion, and apoptosis of HTR-8 cells via the hsa-miR-210-5p/DLX3 axis.

Circular RNAs in Lung Cancer: Recent Advances and Future Perspectives

Globally, lung cancer is the most commonly diagnosed cancer and carries with it the greatest mortality rate, with 5-year survival rates varying from 4–17% depending on stage and geographical differences. For decades, researchers have studied disease mechanisms, occurrence rates and disease development, however, the mechanisms underlying disease progression are not yet fully elucidated, thus an increased understanding of disease pathogenesis is key to developing new strategies towards specific disease diagnoses and targeted treatments. Circular RNAs (circRNAs) are a class of non-coding RNA widely expressed in eukaryotic cells, and participate in various biological processes implicated in human disease. Recent studies have indicated that circRNAs both positively and negatively regulate lung cancer cell proliferation, migration, invasion and apoptosis. Additionally, circRNAs could be promising biomarkers and targets for lung cancer therapies. This review systematically highlights recent advances in circRNA regulatory roles in lung cancer, and sheds light on their use as potential biomarkers and treatment targets for this disease.

Construction of a circRNA-miRNA-mRNA Regulatory Network Reveals Potential Mechanism and Treatment Options for Osteosarcoma

Background

Osteosarcoma is a common malignant primary bone tumor in adolescents and children. Numerous studies have shown that circRNAs were involved in the proliferation and invasion of various tumors. However, the role of circRNAs in osteosarcoma remains unclear. Here, we aimed to explore the regulatory network among circRNA-miRNA-mRNA in osteosarcoma.

Methods

The circRNA (GSE140256), microRNA (GSE28423), and mRNA (GSE99671) expression profiles of osteosarcoma were collected from the Gene Expression Omnibus (GEO) database. Differentially expressed circRNAs, miRNAs and mRNAs were identified. CircRNA-miRNA interactions and miRNA-mRNA interactions were determined by Circular RNA Interactome (CircInteractome) database and microRNA Data Integration Portal (mirDIP) database, respectively. Then, we constructed a regulatory network. Function enrichment analysis of miRNA and mRNA was performed by DIANA-miRPath v3.0 and Metascape database, respectively. mRNAs with significant prognostic value were identified based on expression profiles from The Cancer Genome Atlas (TCGA) database, and we constructed a subnetwork for them. To make the most of the network, we used the CLUE database to predict potential drugs for the treatment of osteosarcoma based on mRNA expression in the network. And we used the STITCH database to analyze and validate the interactions among these drugs and mRNAs, and to further screen for potential drugs.

Results

A total of 9 circRNAs, 19 miRNAs, 67 mRNAs, 54 pairs of circRNA-miRNA interactions and 110 pairs of miRNA-mRNA interactions were identified. A circRNA-miRNA-mRNA network was constructed. Function enrichment analysis indicated that these miRNAs and mRNAs in the network were involved in the process of tumorigenesis and immune response. Among these mRNAs, STC2 and RASGRP2 with significantly prognostic value were identified, and we constructed a subnetwork for them. Based on mRNA expression in the network, three potential drugs, quinacridine, thalidomide and zonisamide, were screened for the treatment of osteosarcoma. Among them, quinacridine and thalidomide have been proved to have anti-tumor effects in previous studies, while zonisamide has not been reported. And a corresponding drug-protein interaction network was constructed.

Conclusion

Overall, we constructed a circRNA-miRNA-mRNA regulatory network to investigate the possible mechanism in osteosarcoma, and predicted that quinacridine, thalidomide and zonisamide could be potential drugs for the treatment of osteosarcoma.

Clinicopathological and prognostic significance of circRNAs in lung cancer: A systematic review and meta-analysis

BACKGROUND

Circular RNAs (circRNAs) regulate multiple pathways during lung cancer pathogenesis. Apart from functional significance, many circRNAs have been shown to be associated with clinicopathological characteristics and predict lung cancer prognosis. Our aim is to summarize the expanding knowledge of clinical roles of circRNAs in lung cancer.

METHODS

A thorough search of literature was conducted to identify articles about the correlation between circRNA expression and its prognostic and clinicopathological values. Biological mechanisms were summarized.

RESULTS

This study included 35 original articles and 32 circRNAs with prognostic roles for lung cancer. Increased expression of 25 circRNAs and decreased expression of 7 circRNAs predicted poor prognosis. For non-small cell lung cancer, changes of circRNAs were correlated with tumor size, lymph node metastasis, distant metastasis, tumor node metastasis (TNM) stage, and differentiation, indicating the major function of circRNAs is to promote lung cancer invasion and migration. Particularly, meta-analysis of ciRS-7, hsa_circ_0020123, hsa_circ_0067934 showed increase of the 3 circRNAs was associated with positive lymph node metastasis. Increase of ciRS-7 and hsa_circ_0067934 was also related with advanced TNM stage. The biological effects depend on the general function of circRNA as microRNA sponge.

CONCLUSIONS

CircRNAs have the potential to function as prognostic markers and are associated with lung cancer progression and metastasis.

Screening of MicroRNA Biomarkers Related to the Progression of Bladder Cancer

Objective: This study aimed to identify the novel microRNAs (miRNAs) for early diagnosis of bladder cancer. Materials and Methods: Differentially expressed miRNAs between early and advanced bladder cancer were identified by differential expression analysis, using miRNA-seq data from The Cancer Genome Atlas (TCGA). The optimal subset of feature miRNAs for pathologic stage prediction was acquired by Random Forest algorithm and was used to construct a support vector machine (SVM) classifier. The performance of the SVM classifier in predicting the progression of bladder cancer samples was validated using an independent validating dataset. An miRNA-regulated target gene network was finally constructed and functional annotation were performed for the target genes. Results: A total of 52 significantly differentially expressed miRNAs were identified between early and advanced bladder cancer samples and 17 of these miRNAs were identified to be feature miRNAs. The 17 feature miRNAs were used to construct an SVM classifier, which showed a high performance in pathologic stage prediction for both training and validating dataset. Besides, our functional annotation analysis showed that the feature miRNAs were significantly involved in biological processes and pathways related to extracellular matrix process and PI3K/Akt signaling. Conclusions: The optimal subset of miRNAs may act as potential therapeutic targets and diagnostic markers of bladder cancer.

Molecular Classification and Tumor Microenvironment Characterization of Gallbladder Cancer by Comprehensive Genomic and Transcriptomic Analysis

Simple Summary

Gallbladder cancer (GBC) is a rare but lethal cancer. Molecular characterization of GBC is insufficient so far, and a comprehensive molecular portrait is warranted to uncover new targets and classify GBC. Clustering analysis of RNA expression revealed two subclasses of 36 GBCs, which reflects the status of the tumor microenvironment (TME) and poor prognosis of GBC, including epithelial–mesenchymal transition (EMT), immune suppression, and the TGF-β signaling pathway. The knockout of miR125B1 in GBC cell lines decreased its invasion ability and altered the EMT pathway. Mutations of the genes related to the TGF-β signaling pathway were enriched in the poor-prognosis/TME-rich cluster of GBCs. This comprehensive molecular analysis provides a new classification of GBCs based on the TME activity, which is involved with EMT and immune suppression for poor prognosis of GBC. This information may be useful for GBC prognosis and therapeutic decision-making.

Abstract

Gallbladder cancer (GBC), a rare but lethal disease, is often diagnosed at advanced stages. So far, molecular characterization of GBC is insufficient, and a comprehensive molecular portrait is warranted to uncover new targets and classify GBC. We performed a transcriptome analysis of both coding and non-coding RNAs from 36 GBC fresh-frozen samples. The results were integrated with those of comprehensive mutation profiling based on whole-genome or exome sequencing. The clustering analysis of RNA-seq data facilitated the classification of GBCs into two subclasses, characterized by high or low expression levels of TME (tumor microenvironment) genes. A correlation was observed between gene expression and pathological immunostaining. TME-rich tumors showed significantly poor prognosis and higher recurrence rate than TME-poor tumors. TME-rich tumors showed overexpression of genes involved in epithelial-to-mesenchymal transition (EMT) and inflammation or immune suppression, which was validated by immunostaining. One non-coding RNA, miR125B1, exhibited elevated expression in stroma-rich tumors, and miR125B1 knockout in GBC cell lines decreased its invasion ability and altered the EMT pathway. Mutation profiles revealed TP53 (47%) as the most commonly mutated gene, followed by ELF3 (13%) and ARID1A (11%). Mutations of ARID1A, ERBB3, and the genes related to the TGF-β signaling pathway were enriched in TME-rich tumors. This comprehensive analysis demonstrated that TME, EMT, and TGF-β pathway alterations are the main drivers of GBC and provides a new classification of GBCs that may be useful for therapeutic decision-making.

Bufalin inhibits the malignant development of non-small cell lung cancer by mediating the circ_0046264/miR-522-3p axis

BACKGROUND

Bufalin is an active component of the traditional Chinese medicine "Chan Su" and is reported to play anti-tumor roles in cancer development, but its functional mechanism is largely unclear. This study intends to explore a potential action mode of bufalin in NSCLC.

MATERIALS AND METHODS

The malignant properties of NSCLC, including cell viability, proliferation, adhesion capacity, migration and invasion, were monitored by cell counting kit-8 (CCK-8), adhesion assay and transwell assay, respectively. The expression of circ_0046264 and miR-522-3p was detected by quantitative real-time polymerase chain reaction (qRT-PCR). The expression of proliferation- and migration-related markers was examined by western blot. The putative relationship between circ_0046264 and miR-522-3p was verified by dual-luciferase reporter assay, RIP assay and RNA pull-down assay. Animal experiments in nude mice were performed to investigate the role of bufalin in vivo.

RESULTS

Bufalin treatment inhibited cell viability, colony formation, cell adhesion capacity, migration and invasion in NSCLC cells. Bufalin facilitated the expression of circ_0046264, and circ_0046264 overexpression also inhibited NSCLC cell viability, colony formation, cell adhesion capacity, migration and invasion. Besides, circ_0046264 knockdown partially counteracted the effects of bufalin. Further, miR-522-3p was identified as a target of circ_0046264, and its deficiency reversed the effects of circ_0046264 knockdown to suppress malignant activities of NSCLC cells. In addition, bufalin restrained the tumor growth and development in vivo via enhancing the expression of circ_0046264.

CONCLUSION

Bufalin played an anti-tumor role in NSCLC by modulating the circ_0046264/miR-522-3p pathway, which might be a potential functional mechanism of bufalin in NSCLC.

Circ_0091579 enhances the malignancy of hepatocellular carcinoma via miR-1287/PDK2 axis

Several articles have indicated that circular RNAs are involved in pathogenesis of human cancers. Nevertheless, the role of circ_0091579 in hepatocellular carcinoma (HCC) progression remains to be revealed. Quantitative reverse transcriptase polymerase chain reaction was carried out to examine the expression of circ_0091579 and miR-1287. The proliferation of HCC cells was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Flow cytometry was performed to analyze cell cycle progression and apoptosis. Western blot assay was conducted to detect the protein expression of CyclinD1, Cleaved caspase3, and pyruvate dehydrogenase kinase 2 (PDK2). Cell glycolysis was evaluated by measuring the uptake of glucose, the production of lactate, and extracellular acidification rate. The target relationship between miR-1287 and circ_0091579 or PDK2 was verified by dual-luciferase reporter assay, RNA immunoprecipitation assay, and RNA-pull down assay. The enrichment of circ_0091579 was enhanced in HCC tissues (n = 77) and four HCC cell lines (HB611, Huh-7, MHCC97, and SNU423) compared with adjacent non-tumor tissues (n = 77) and normal human liver cell line THLE-2. Circ_0091579 mediated the promotion of proliferation and glycolysis and the suppression of apoptosis of HCC cells. MiR-1287 was a direct target of circ_0091579 in HCC cells. MiR-1287 knockdown reversed the effects caused by circ_0091579 interference on the functions of HCC cells. PDK2 could bind to miR-1287 in HCC cells. Circ_0091579 upregulated the enrichment of PDK2 by acting as a sponge of miR-1287 in HCC cells. The influence caused by circ_0091579 intervention on HCC cells was attenuated by overexpression of PDK2. Circ_0091579 interference impeded the progression of HCC in vivo. Circ_0091579 deteriorated HCC by promoting the proliferation and glycolytic metabolism and suppressing the apoptosis of HCC cells via miR-1287/PDK2 axis.

The cross-talk between signaling pathways, noncoding RNAs and DNA damage response: Emerging players in cancer progression

The DNA damage response (DDR) pathway's primary purpose is to maintain the genome structure's integrity and stability. A great deal of effort has done to understand the exact molecular mechanisms of non-coding RNAs, such as lncRNA, miRNAs, and circRNAs, in distinct cellular and genomic processes and cancer progression. In this regard, the ncRNAs possible regulatory role in DDR via modulation of key components expression and controlling repair signaling pathway activation is validated. Therefore, in this article, we will discuss the latest developments of ncRNAs contribution in different aspects of DNA repair through regulation of ATM-ATR, P53, and other regulatory signaling pathways.

Circular RNA circ_0046264 Suppresses Osteosarcoma Progression via microRNA-940/Secreted Frizzled Related Protein 1 Axis

Circular RNAs (circRNAs) feature prominently in regulating tumor progression. The study aims to investigate the role and mechanism of circ_0046264 in osteosarcoma. In this study, dysregulated circRNAs in osteosarcoma tissues and adjacent tissues were screened out by analyzing circRNA microarray (GSE140256). The expressions of circ_0046264 in 58 osteosarcoma tissues and 4 osteosarcoma cell lines were detected by quantitative real-time polymerase chain reaction. Subsequently, the relationship of circ_0046264 expression level and clinical features were analyzed. Ethyldeoxyuridine assay and Transwell assay were employed to detect cell viability, migration and invasion. Dual-luciferase reporter assay was adopted to confirm the targeting relationships between circ_0046264 and microRNA-940 (miR-940), as well as miR-940 and secreted frizzled related protein 1 (SFRP1). SFRP1 expression was determined by western blot. Here, we demonstrated that circ_0046264 was greatly down-regulated in osteosarcoma and was inversely related to tumor size and Ki67 expression. Functional assays validated that circ_0046264 could restrain the proliferation, migration and invasion. Mechanistically, circ_0046264 could adsorb miR-940 and indirectly modulate SFRP1 expression. Furthermore, the transfection of miR-940 mimics or SFRP1 small interfering RNA could reverse the impact of circ_0046264 overexpression on the growth, migration and invasion of osteosarcoma cells. Taken together, circ_0046264 is a tumor suppressor to inhibit the osteosarcoma progression via modulating the miR-940 / SFRP1 axis.

CircRNAs as promising biomarker in diagnostic and prognostic of lung cancer: An updated meta-analysis

BACKGROUND

As a class of endogenous non-coding RNAs with closed-loop structure, circular RNAs (circRNAs) are receiving more and more attention. CircRNAs have been reported to be widely expressed in various human cancers and are implicated in tumorigenesis and progression. The present study aimed to systematically evaluate the clinicopathological, diagnostic and prognostic values of circRNAs in lung cancer.

METHODS

We searched literature from PubMed, Web of science, Cochrane Library, EMBASE and Ovid online databases up to May 29, 2020. Statistical analyses were undertaken based on Stata 11.0, Meta-DiSc 1.4, and RevMan 5.3 software.

RESULTS

Finally, a total of 63 eligible articles were included in our meta-analysis, including 18 studies for diagnosis, 22 studies for prognosis and 57 studies for clinicopathological features. In terms of diagnostic values, circRNAs could discriminate between lung cancer patients and the normal individuals with a relatively high pooled area under the curve (AUC) of 0.83 (95%CI, 0.80-0.86). For the prognostic values, we found that elevated expression of oncogenic circRNAs could predict poor survival outcomes based on multivariate analysis (HR = 2.430, 95%CI = 2.003-2.948, P < 0.001 for OS; HR = 2.228, 95%CI = 1.289-3.853, P = 0.004 for DFS) while tumor-suppressor circRNAs was correlated with better OS in univariate analysis (HR = 0.627, 95%CI = 0.519-0.757, P < 0.001). The pooled results suggested that elevated expression of carcinogenic circRNAs was associated with tumor size (OR = 1.676, 95%CI = 1.209-2.323, P = 0.002), smoking statue (OR = 1.260, 95%CI = 1.062-1.494, P = 0.008), TNM stage (OR = 2.345, 95%CI = 1.617-3.399, P < 0.001), differentiation grade (OR = 1.843, 95%CI = 1.228-2.765, P = 0.003), and lymphatic metastasis (OR = 2.097, 95%CI = 1.482-2.967, P < 0.001). Moreover, the expression of tumor-suppressor circRNAs was related to the improved clinicopathological features (lymphatic metastasis: OR = 0.536, 95%CI = 0.311-0.926, P = 0.025).

CONCLUSIONS

Our meta-analysis demonstrated that circRNAs could be used as feasible and important biomarkers for diagnosis, prognosis and clinicopathological features in lung cancer.

Circular RNA circ_0026359 Enhances Cisplatin Resistance in Gastric Cancer via Targeting miR-1200/POLD4 Pathway

Human gastric cancer is one of the most common malignant tumors with a poor prognosis. Cisplatin (CDDP) is a well-known first-line chemotherapeutic drug. Acquired resistance retards the clinical application of CDDP in gastric cancer. In this study, circular RNA circ_0026359 was demonstrated to be overexpressed in gastric cancer tissues/cells compared with normal gastric tissues/cells and was overexpressed in CDDP-resistant gastric cancer tissues/cells compared with CDDP-sensitive gastric cancer tissues/cells. High levels of circ_0026359 were associated with low overall survival (OS) and relapse-free survival (RFS) rates in gastric cancer patients. circ_0026359 was examined to promote CDDP resistance in gastric cancer cells. circ_0026359 directly interacted and negatively regulated miR-1200. POLD4 was a direct target of miR-1200. miR-1200/POLD4 pathway mediated the promoting role of circ_0026359 in CDDP resistance of gastric cancer. circ_0026359 could be used as a potential target for CDDP-resistant gastric cancer therapy.

FOXA1-induced circOSBPL10 potentiates cervical cancer cell proliferation and migration through miR-1179/UBE2Q1 axis

Background

Recently, extensive evidence has clarified the crucial role of circular RNAs (circRNAs) as a pro-tumor or anti-cancer participant in human malignancies. A new circRNA derived from oxysterol binding protein like 10 (OSBPL10) (circOSBPL10) has not been researched in cervical cancer (CC) yet.

Methods

The expression of molecules was analyzed by RT-qPCR or western blot. Several functional assays were applied to explore the biological influence of circOSBPL10 on CC. The interaction between RNAs was estimated via luciferase reporter, RNA immunoprecipitation and RNA pull-down assays.

Results

CircOSBPL10 characterized with cyclic structure was revealed to possess elevated expression in CC cells. CircOSBPL10 downregulation elicited suppressive impacts on CC cell proliferation and migration. Interestingly, circOSBPL10 regulated CC progression by interacting with microRNA-1179 (miR-1179). Moreover, ubiquitin conjugating enzyme E2 Q1 (UBE2Q1) targeted by miR-1179 was positively regulated by circOSBPL10 in CC. Furthermore, enhanced UBE2Q1 expression or suppressed miR-1179 level countervailed the repressive effect of circOSBPL10 depletion on the malignant phenotypes of CC cells. Moreover, forkhead box A1 (FOXA1) was confirmed to induce circOSBPL10 expression in CC cells.

Conclusions

FOXA1-induced circOSBPL10 facilitates CC progression through miR-1179/UBE2Q1 axis, highlighting a strong potential for circOSBPL10 to serve as a promising therapeutic target in CC.

Diagnostic and prognostic values of circular RNAs for lung cancer: a meta-analysis

Circular RNAs (circRNAs) may serve as potential biomarkers for patients with lung cancer. The aim of this meta-analysis was to analyse the diagnostic, prognostic and clinicopathological values of circRNAs in lung cancer patients. A systematic search of PubMed, Embase, Web of Science, Scopus and the Cochrane Library databases was performed for relevant articles from inception to 29 January 2020. Pooled parameters including sensitivity, specificity and area under the curve (AUC) were used to assess the diagnostic performance, HRs and 95% CIs were used to evaluate overall survival (OS) and ORs were used to estimate clinicopathological parameters. 52 studies from 45 articles were enrolled in this study, including 17 on diagnosis and 35 on prognosis. For diagnostic values, circRNAs could discriminate lung cancer patients from the controls, with AUC of 0.83 (95% CI: 0.79 to 0.86), a relatively high sensitivity of 0.77 (95% CI: 0.73 to 0.81) and specificity of 0.75 (95% CI: 0.71 to 0.79). For prognostic significances, overexpression of 23 upregulated circRNAs was relevant to a poor prognosis (OS: HR=2.21, 95% CI: 1.96 to 2.49, p<0.001), and overexpression of 9 downregulated circRNAs was correlated with a favourable prognosis (OS: HR=0.62, 95% CI: 0.53 to 0.73, p<0.001). As for clinicopathological parameters, high expression of 23 upregulated circRNAs was associated with unfavourable clinicopathological features while 9 downregulated circRNAs proved the contrary. In conclusion, this study confirmed that circRNAs might serve as important biomarkers for diagnostic and prognostic values of lung cancer.

circRNA-miRNA-mRNA regulatory network in human lung cancer: an update

Circular RNAs, as hopeful diagnosis markers and therapeutic molecules, have been studied, probed and applied into several diseases, such as cardiovascular diseases, systemic lupus erythematosus, leukemia, pulmonary tuberculosis, and cancer especially. Recently, mounting evidence has supported that circRNAs play a key role in the tumorigenesis, progress, invasion and metastasis in lung cancer. Its special structure—3′–5′ covalent loop—allow it to execute several special functions in both normal eukaryotic cells and cancer cells. Our review summaries the latest studies on characteristics and biogenesis of circRNAs, and highlight the regulatory functions about miRNA sponge of lung-cancer-related circRNAs. In addition, the interaction of the circRNA-miRNA-mRNA regulatory network will also be elaborated in detail in this review. Therefore, this review can provide a new idea or strategy for further development and application in clinical setting in terms of early-diagnosis and better treatment.

TMPO-AS1/miR-98-5p/EBF1 feedback loop contributes to the progression of bladder cancer

As reported in numerous studies, long non-coding RNAs (lncRNAs) exert significant effect on the regulation of tumor development. LncRNA TMPO antisense RNA 1 (TMPO-AS1) has been confirmed to be implicated in the development of several cancers. However, its clinical significance is still largely unknown in bladder cancer (BCa). In this study, high expression of TMPO-AS1 was revealed in BCa tissues and cell lines, and TMPO-AS1 predicted poor prognosis. Moreover, TMPO-AS1 facilitated cell growth. Additionally, TMPO-AS1 also boosted the migration and invasion of BCa cells. Mechanistically, overexpressed EBF transcription factor 1 (EBF1) in BCa cell was verified to promote the transcription of TMPO-AS1. Later, we found that TMPO-AS1 was a cytoplasmic RNA and could sponge miR-98-5p. Besides, it was validated that EBF1 is a target gene of miR-98-5p and negatively correlated with miR-98-5p in terms of expression level. According to the results of rescue experiments, we observed that EBF1 overexpression restored the repressive effect of TMPO-AS1 silencing on BCa development. Our research is the first to disclose the biological role and molecular mechanism of TMPO-AS1 in BCa, and TMPO-AS1 might be identified as a new therapeutic target for BCa patients.

Circular RNA circ‑ACACA regulates proliferation, migration and glycolysis in non‑small‑cell lung carcinoma via miR‑1183 and PI3K/PKB pathway

Non-small cell lung carcinoma (NSCLC) accounts for 85% of all lung cancers and the five-year survival rate is ~1% in the late stage. Circular RNAs (circRNAs) were reported to be involved in the progression of diverse human cancers. However, the role of circ-ACACA in NSCLC progression remains elusive. Quantitative polymerase chain reaction was conducted to detect the expression levels of circ-ACACA and microRNA (miR)-1183 in NSCLC tissues and cells. A Cell Counting Kit-8 assay and transwell assay were employed to check proliferation and migration, respectively. Metabolic alternations in NSCLC cells were monitored by the Seahorse XFe96 analyzer. The protein levels of cellular myelocytomatosis, matrix metallopeptidase 9, glucose transporter 1, phosphatase and tensin homolog, phosphoinositide 3-kinases (PI3K), phosphorylated PI3K (p-PI3K), protein kinase B (PKB) and p-PKB in samples were measured by western blotting. The interaction between circ-ACACA and miR-1183 was predicted by circular RNA Interactome, which was verified by dual-luciferase reporter assay, RNA immunoprecipitation assay and RNA pull-down assay. Xenograft tumor model was established to investigate the biological roles of circ-ACACA in vivo. The level of circ-ACACA was markedly upregulated in NSCLC tissues and cells, which was contrary to the expres-sion of miR-1183. Knockdown of circ-ACACA inhibited proliferation and migration of NSCLC cells and also reduced the glycolysis rate. In addition, miR-1183 was a target of circ-ACACA and its downregulation reversed circ-ACACA silencing-mediated inhibitory impact on NSCLC progression. Further studies indicated that circ-ACACA regulated the PI3K/PKB pathway through interacting with miR-1183 and downregulation of circ-ACACA suppressed tumor growth. Knockdown of circ-ACACA impeded NSCLC progression by sponging miR-1183 and inactivating the PI3K/PKB signaling pathway.

Development of a Novel Six-miRNA-Based Model to Predict Overall Survival Among Colon Adenocarcinoma Patients

Introduction: Colon carcinoma is a common malignant tumor worldwide. Accurately predicting prognosis of colon adenocarcinoma (CA) patients may facilitate clinical individual decision-making. Many studies have reported that microRNAs (miRNAs) were associated with prognosis for patients with colon carcinoma. This study aimed to identify the prognosis-related miRNAs for predicting the overall survival (OS) of CA patients. Methods: Firstly, we analyzed the CA datasets from the Cancer Genome Atlas (TCGA), and looked for the prognosis-related miRNAs. Then, we developed a novel prediction model based on these miRNAs and the clinical characteristics. Time-dependent receiver operating characteristics (ROC) curves and calibration plots were used to evaluate the discrimination and accuracy of the signature and model. Finally, cell function assays and bioinformatics analyses were performed to evaluate the role of these selected miRNAs in modulating biological process in CA. Results: Six prognosis-related miRNAs were included in the miRNA-based signature, and it could effectively distinguish low-risk patients and high-risk patients. Furthermore, we established a prognostic model incorporating the six-miRNA-based signature and clinical characteristics. Areas under curves (AUCs) indicated that the six-miRNA-based model has a better predictive ability than TNM stage (AUC: 0.805 vs. 0.694). The calibration plots suggested close agreement between model predictions and actual observations. GO analysis showed that the target genes of these miRNAs are mainly involved in enrichment in protein binding and regulation of transcript and cytosol. KEGG pathway enrichment analysis indicated that these genes were mainly enriched in PI3K-Akt signaling pathway. Finally, we found that the five miRNAs except miR-152 were upregulated in tumor tissues and CA cells. The functional experiments revealed that miR-1245a, miR-3682, miR-33b, and miR-5683 promoted the migratory abilities and proliferation of CA cell, whereas miR-152 showed opposite effects. However, miR-4444-2 did not influence the migratory ability and proliferation of CA cell. Conclusions: In conclusion, we developed a novel six-miRNA-based model to predict 5-year survival probabilities for CA patients. This model has the potential to facilitate individualized treatment decisions.

miR-1245a promotes the proliferation and invasion of colon adenocarcinoma by targeting BRCA2

Background

Colon adenocarcinoma (CA) is the most common one with poor survival in colon cancer. This study aims to investigate the effect of miR-1245a on the process of CA cells and its target gene BRCA2.

Methods

The expression of CA tissues and cells were evaluated by q RT-PCR. Then we explore the association between expression of miR-1245a and prognosis in the CA patients from the TCGA database. CCK8 assays, colony formation assays were performed to explore the effect of miR-1245a in CA cell proliferation. The invasion ability of CA cells was evaluated by Transwell assays. Western blot was performed to assess the BRCA2 expression. Luciferase reporter assay was employed to scrutinize the relationship between miR-1245a and BRCA2. Finally, rescue experiments were performed through BRCA2 downregulation and miR-1245a inhibitors by using colony formation assay and Transwell invasion assay.

Results

miR-1245a is upregulated in CA cells and tissues. Additionally, the high expression of miR-1245a was related to poor survival. CCK8 assays, colony formation assays and Transwell assays showed that miR-1245a promotes the proliferation and invasion of CA cells. The luciferase reporter assay indicated that miR-1245a targeted BRCA2 and inhibited its expression. The rescue experiment further showed that miR-1245a could restore the effect of BRCA2 on CA.

Conclusions

miR-1245a promotes the proliferation and invasion of CA by targeting BRCA2.Our results suggested that miR-1245a could be a potential biomarker for CA progression.

Circular RNA in Lung Cancer Research: Biogenesis, Functions, and Roles

Lung cancer is one of the most common and deadly malignancies worldwide, in spite of advances in targeted therapy in recent years. An effective strategy for lung cancer prevention remains a major problem. Advances in next-generation sequencing have helped in understanding the RNA and identifying novel circular RNAs (circRNAs) that may have a broad impact on the early diagnosis and treatment of lung cancer. The circRNAs, exhibiting spatiotemporal-specific expression, are stable and conserved and present diverse biological functions in the normal and diseased states, including cancer. In this review, we summarize the recent advances in elucidating the functional role of circRNAs in lung cancer pathogenesis and discuss their potential mechanisms.

Construction and Validation of a Protein Prognostic Model for Lung Squamous Cell Carcinoma

Lung squamous cell carcinoma (LUSCC), as the major type of lung cancer, has high morbidity and mortality rates. The prognostic markers for LUSCC are much fewer than lung adenocarcinoma. Besides, protein biomarkers have advantages of economy, accuracy and stability. The aim of this study was to construct a protein prognostic model for LUSCC. The protein expression data of LUSCC were downloaded from The Cancer Protein Atlas (TCPA) database. Clinical data of LUSCC patients were downloaded from The Cancer Genome Atlas (TCGA) database. A total of 237 proteins were identified from 325 cases of LUSCC patients based on the TCPA and TCGA database. According to Kaplan-Meier survival analysis, univariate and multivariate Cox analysis, a prognostic prediction model was established which was consisted of 6 proteins (CHK1_pS345, CHK2, IRS1, PAXILLIN, BRCA2 and BRAF_pS445). After calculating the risk values of each patient according to the coefficient of each protein in the risk model, the LUSCC patients were divided into high risk group and low risk group. The survival analysis demonstrated that there was significant difference between these two groups (p= 4.877e-05). The area under the curve (AUC) value of the receiver operating characteristic (ROC) curve was 0.699, which suggesting that the prognostic risk model could effectively predict the survival of LUSCC patients. Univariate and multivariate analysis indicated that this prognostic model could be used as independent prognosis factors for LUSCC patients. Proteins co-expression analysis showed that there were 21 proteins co-expressed with the proteins in the risk model. In conclusion, our study constructed a protein prognostic model, which could effectively predict the prognosis of LUSCC patients.

Potential Diagnostic and Prognostic Biomarkers of Circular RNAs for Lung Cancer in China

Emerging evidence demonstrated that circular RNAs (circRNAs) were dysregulated in lung cancer, indicating that circRNAs might serve as novel diagnostic and prognostic biomarkers for lung cancer. However, the clinical value of circRNAs on lung cancer remains unclear. This study aimed to evaluate the efficiency of circRNAs in the diagnosis and prognosis for lung cancer in China. 2122 Chinese individuals were enrolled in this investigation for assessment of diagnostic value and examination of prognostic analysis. In the diagnostic analysis, the pooled sensitivity, specificity, PLR, NLR, DOR, and AUC of the sROC curve with their 95% CIs were 0.80 (95%CI: 0.74-0.84), 0.80 (95%CI: 0.73-0.86), 3.97 (95%CI: 2.80-5.62) and 0.26 (95%CI: 0.19-0.34), 15.51 (95%CI: 8.76-24.47), and 0.85 (95%CI: 0.82-0.88), respectively. As for the prognostic power of circRNAs, lung cancer patients with higher expression levels of circRNAs tend to possess lower overall survival with the overall pooled HR (1.70, 95%CI: 1.26-2.29). Furthermore, in stratified analysis, upregulated and downregulated circRNAs were manifested to exert significant effects on prognosis with HR values of 2.17 (95%CI: 1.74-2.72) and 0.52 (95%CI: 0.34-0.80). This study validates that circRNAs are promising diagnostic and predictive biomarkers for lung cancer patients in China.

Progress in research on the role of circular RNAs in lung cancer

Background

Circular RNA (circRNA), as a covalently closed circular RNA molecule, is widely present, which is recognized as a competing endogenous RNA. A large number of differentially expressed circRNAs have been identified and are recognized as potential biomarkers for the diagnosis of tumors.

Main body

CircRNAs play an important role in the regulation of cell signaling pathways. The main biological functions of circRNAs include acting as miRNA sponges, regulating the transcription of the parental genes, and acting as adapters to regulate the interactions between proteins and encoding proteins. Compared with normal tissues, there are differentially expressed circRNAs in lung cancer tissue, and the expression levels of circRNAs are correlated with clinicopathological features of lung cancer. Their roles in pathway regulation are described, and the diagnostic and prognostic values are further evaluated.

Conclusion

In lung cancer, circRNAs participate in the proliferation, migration, and invasion, acting as a competitive endogenous RNA. Differentially expressed circRNAs may serve as non-invasive diagnostic markers for lung cancers. Further investigation of the roles of circRNAs in the pathogenesis and regulatory pathways is conducive to the development of novel approaches for the diagnosis and accurate treatment of lung cancers.