Circ_0078767 suppresses non-small-cell lung cancer by protecting RASSF1A expression via sponging miR-330-3p

METTL16-dependent miR-146b-5p m6A modification remodeling sensitize NSCLC to osimertinib via activating PI3K/AKT signaling

BACKGROUND

Non-small-cell lung cancer (NSCLC) is one of the most common malignant tumors, with poor prognosis and increasing osimertinib therapy resistance. Revealing mechanisms of NSCLC progression and therapy resistance remains critical. The aim of this study was to elucidate the molecular mechanism of miR-146b-5b-5p m6A modification and underlying function in regulating the proliferation and osimertinib resistance of NSCLC.

METHODS

TCGA, GEO datasets were used to analyze the differential expression of miR-146b-5p in NSCLC and adjacent tissues, and its impact on prognosis. Then the effects of miR-146b-5p on the proliferation and osimertinib of A549 and HCC827 cells were investigated through proliferation experiments, colony formation assay and IC50 assay. The regulatory mechanism of miR-146b-5p on the PI3K/AKT signaling pathway and its interaction in cancer progression were investigated through Western blots, dual-luciferase reporter assay, and rescue experiments.

RESULTS

miR-146b-5p was significantly upregulated in NSCLC tissue and represented worse prognosis. miR-146b-5p mimic significantly enhanced proliferation and osimertinib resistance, while miR-146b-5p inhibitor inhibited above phenotype. Through bioinformatic analysis and experimental results, miR-146b-5p interacted directly with PTEN mRNA and activated subsequent signaling pathway activation. PI3K/AKT inhibitor could eliminate the tumorigenic effects of miR-146b-5p mimic on the progression of NSCLC, while PI3K/AKT agonist could rescue the inhibition effect of miR-146b-5p inhibitor group cells. Further, methyltransferase METTL16 is responsible for miR-146b m6A modification. Modified miR-146b-5p promotes osimertinib resistance through downstream PI3K/AKT activation.

CONCLUSIONS

In summary, we found that METTL16 mediated miR-146b-5p m6A modification promoted the proliferation and osimertinib resistance of NSLCL by activating PI3K/AKT signaling pathway. Our study is expected to provide a novel insight and potential therapeutic target for NSCLC osimertinib resistance.

Emerging role and clinical applications of circular RNAs in human diseases

Circular RNAs (circRNAs) are a large family of non-coding RNAs characterized by a single-stranded, covalently closed structure, predominantly synthesized through a back-splicing mechanism. While thousands of circRNAs have been identified, only a few have been functionally characterized. Although circRNAs are less abundant than other RNA types, they exhibit exceptional stability due to their covalently closed structure and demonstrate high cell and tissue specificity. CircRNAs play a critical role in maintaining cellular homeostasis by influencing gene transcription, translation, and post-translation processes, modulating the immune system, and interacting with mRNA, miRNA, and proteins. Abnormal circRNA expression has been associated with a wide range of human diseases and various infections. Due to their remarkable stability in body fluids and tissues, emerging research suggests that circRNAs could serve as diagnostic and therapeutic biomarkers for these diseases. This review focuses on the emerging role of circRNAs in various human diseases, exploring their biogenesis, molecular functions, and potential clinical applications as diagnostic and therapeutic biomarkers with current evidence, challenges, and future perspectives. The key theme highlights the significance of circRNAs in regulating gene expression, their involvement in diseases like cancer, neurodegenerative disorders, cardiovascular diseases, and diabetes, and their potential use in translational medicine for developing novel therapeutic strategies. We also discuss recent clinical trials involving circRNAs. Thus, this review is important for both basic researchers and clinical scientists, as it provides updated insights into the role of circRNAs in human diseases, aiding further exploration and advancements in the field.

Circular RNA SPECC1 promoted tumorigenesis and osimertinib resistance in lung adenocarcinoma via a circular RNA-microRNA network

Background

Tyrosine kinase inhibitors (TKIs) are the first-line therapy for patients with non-small cell lung cancer (NSCLC) with sensitized mutations in the epidermal growth factor receptor (EGFR). However, resistance to TKIs is a major clinical issue that affects the survival and prognosis of the patients, with the mechanisms underlying this resistance remaining elusive. Circular RNAs (circRNAs) are a class of single-stranded, covalently closed RNA molecules, which are generated from pre-messenger RNAs (mRNAs) through back splicing. The aim of this study was to investigate the role of cRNA SPECC1 in promoting resistance to TKIs in NSCLC and to explore its potential involvement in tumorigenesis and metastasis of lung adenocarcinoma (LUAD).

Methods

In this study, we identified differentially expressed genes through RNA sequencing from three tumor samples obtained from patients with poor postoperative TKI treatment outcomes. Validation was performed using quantitative real-time polymerase chain reaction (qRT-PCR) and cell function experiments. We further constructed a competing endogenous RNA (ceRNA) network and performed Gene Ontology (GO) analysis to explore the underlying mechanisms of circRNA.

Results

SPECC1 circular RNA (circSPECC1) was found to be significantly upregulated in tumors as compared to adjacent tissues. Knockdown of circSPECC1 in NSCLC cell lines resulted in decreased proliferation, migration, and invasion. Additionally, apoptosis was increased in cell lines with TKI-sensitive EGFR mutations when treated with osimertinib.

Conclusions

circSPECC1 may promote TKI resistance and contribute to the tumorigenesis and metastasis of NSCLC. This study offers a novel perspective on TKI resistance research at the RNA level.

Circ6834 suppresses non-small cell lung cancer progression by destabilizing ANHAK and regulating miR-873-5p/TXNIP axis

BACKGROUND

Circular RNAs (circRNAs) play important roles in cancer progression and metastasis. However, the expression profiles and biological roles of circRNAs in non-small cell lung cancer (NSCLC) remain unclear.

METHODS

In this study, we identified a novel circRNA, hsa_circ_0006834 (termed circ6834), in NSCLC by RNA-seq and investigated the biological role of circ6834 in NSCLC progression in vitro and in vivo. Finally, the molecular mechanism of circ6834 was revealed by tagged RNA affinity purification (TRAP), western blot, RNA immunoprecipitation, dual luciferase reporter gene assays and rescue experiments.

RESULTS

Our results showed that circ6834 was downregulated in NSCLC tumor tissues and cell lines. Circ6834 overexpression inhibited NSCLC cell growth and metastasis both in vitro and in vivo, while circ6834 knockdown had the opposite effect. We found that TGF-β treatment decreased circ6834 expression, which was associated with the QKI reduction in NSCLC cells and circ6834 antagonized TGF-β-induced EMT and metastasis in NSCLC cells. Mechanistically, circ6834 bound to AHNAK protein, a key regulator of TGF-β/Smad signaling, and inhibited its stability by enhancing TRIM25-mediated ubiquitination and degradation. In addition, circ6834 acted as a miRNA sponge for miR-873-5p and upregulated TXNIP gene expression, which together inactivated the TGF-β/Smad signaling pathway in NSCLC cells.

CONCLUSION

In conclusion, circ6834 is a tumor-suppressive circRNA that inhibits NSCLC progression by forming a negative regulatory feedback loop with the TGF-β/Smad signaling pathway and represents a novel therapeutic target for NSCLC.

Up-regulation of NCAPG mediated by E2F1 facilitates the progression of osteosarcoma through the Wnt/β-catenin signaling pathway

Background

In recent years, there are few reports on non-SMC condensin I complex subunit G (NCAPG) in osteosarcoma. Our study aims to explore the biological role of NCAPG in osteosarcoma and its underlying molecular mechanism and to further clarify the reasons for the abnormal expression of NCAPG in osteosarcoma.

Methods

Here, we mined The Cancer Genome Atlas (TCGA) Program public database through bioinformatics methods, analyzed the differential expression of NCAPG in sarcoma tissue and normal tissue, and explored the relationship between NCAPG expression level and sarcoma tissue differentiation, including tumor recurrence, metastasis, and patient survival. Next, the transcription factors responsible for the abnormal expression of NCAPG in osteosarcoma tumors were predicted by multiple online website tools and verified via cellular experiments. Subsequently, loss of function and cell phenotype experiments were performed to confirm the effect of NCAPG on the malignant biological behavior of osteosarcoma cells. Mechanistically, by reviewing the literature, we found that NCAPG can affect the malignant progression of many solid tumors by regulating the Wnt/β-catenin signaling pathway. Therefore, we preliminarily investigated the potential effect of NCAPG on this pathway via western blot experiments in osteosarcoma.

Results

Increased expression of NCAPG was found in sarcoma compared to normal tissues, which was positively correlated with poor differentiation, metastasis, and poor prognosis. Combining the transcription factor prediction results, correlation analysis, and expression level in the TCGA public database with validation outcomes of in vitro cell assays, we found that E2F transcription factor 1 (E2F1) regulated the increased expression of NCAPG in osteosarcoma. The results of cell phenotype experiments showed that silencing NCAPG could inhibit the proliferation, migration, and invasion of osteosarcoma cells. The preliminary mechanistic investigation suggested that NCAPG may affect osteosarcoma progression through the Wnt/β-catenin pathway.

Conclusions

Our data reveal that E2F1 facilitates NCAPG expression in osteosarcoma by regulating the transcription of the NCAPG gene. Up-regulation of NCAPG promotes osteosarcoma progression via the Wnt/β-catenin signaling axis.

circPDK1 competitively binds miR-4731-5p to mediate GIGYF1 expression and increase paclitaxel sensitivity in non-small cell lung cancer

OBJECTIVE

To investigate the action of circPDK1 in paclitaxel (PTX) resistance in non-small cell lung cancer (NSCLC).

METHODS

circPDK1, miR-4731-5p, and GIGYF1 levels were determined by RT-qPCR and Western blot. Cell proliferation was detected by CCK-8 and colony formation assay, apoptosis by flow cytometry, invasion by Transwell assay. The targeting relationship between miR-4731-5p and circPDK1 or GIGYF1 was confirmed by dual luciferase reporter gene and RIP assay. A xenograft tumor model was established to determine the role of circPDK1 in PTX resistance.

RESULTS

circPDK1 was overexpressed in PTX-resistant NSCLC, and depleting circPDK1 hampered proliferation and invasion of PTX-resistant cells, activated apoptosis, and improved PTX sensitivity. circPDK1 bound to miR-4731-5p, and increasing miR-4731-5p expression salvaged the effect of circPDK1 depletion on PTX resistance. miR-4731-5p directly targeted GIGYF1, and upregulating GIGYF1 offset the promoting effect of circPDK1 knockdown on PTX sensitivity. NSCLC tumor growth was inhibited and PTX sensitivity improved when circPDK1 was suppressed.

CONCLUSION

Depleting circPDK1 promotes PTX sensitivity of NSCLC cells via miR-4731-5p/GIGYF1 axis, thereby inhibiting NSCLC pregnancy.

The Combination of SHOX2 and RASSF1A DNA Methylation Had a Diagnostic Value in Pulmonary Nodules and Early Lung Cancer

INTRODUCTION

The study explored the effects of SHOX2 and RASSF1A DNA methylation in lung cancer (LC).

METHOD

Bronchoalveolar lavage fluid (BALF) samples as well as LC and normal adjacent tissues were collected from 72 LC patients and 35 patients with benign pulmonary nodules. Quantitative analysis of SHOX2 and RASSF1A DNA methylation was performed in benign pulmonary nodules and different stages of LC. The diagnostic value of SHOX2 and RASSF1A DNA methylation in LC and benign pulmonary nodules was determined by receiver operating characteristics analysis. Gain/loss-of-function experiments were constructed in LC cells and mouse models of xenograft and pulmonary nodule metastasis. The levels of SHOX2 and transfer-associated genes were tested through quantitative reverse transcription polymerase chain reaction and Western blot. Malignant phenotype of LC cells was assessed by functional experiment. The tumor volume and weight of mice in xenograft models were measured. Pulmonary nodule metastasis was determined through HE staining assay. 5-azacytidine appeared as a positive control drug.

RESULT

SHOX2 DNA methylation or RASSF1A DNA methylation had diagnostic efficiency in pulmonary nodules and early LC, with the two combined having better diagnostic value. SHOX2 expression was upregulated in LC. Similar to 5-azacytidine, SHOX2 knockdown inhibited LC cell viability, migration, and invasion in vitro as well as restrained LC tumorigenesis and pulmonary nodule metastasis in vivo, whereas overexpressed SHOX2 had the opposite effects.

CONCLUSION

The combination of SHOX2 and RASSF1A DNA methylation had a diagnostic value in pulmonary nodules and early LC. SHOX2 positively modulated the tumorigenesis and metastasis of LC by regulating DNA methylation processes.

Circ_0020123 promotes non-small cell lung cancer progression via miR-146a-5p mediated regulation of EIF4G2 expression

BACKGROUND

Circular RNAs (circRNAs) have been reported to be involved in the initiation and development of cancers. The aim of this study was to determine the role of a circRNA, circ_0020123, in the development of non-small cell lung cancer (NSCLC).

METHODS

The expression of circ_0020123, microRNA-146a-5p (miR-146a-5p), and eukaryotic translation initiation factor 4 gamma 2 (EIF4G2) mRNA was detected by quantitative real-time PCR (qPCR). Western blot was used to determine the protein levels of cyclin D1, Bax, MMP-9, and EIF4G2. Cell proliferation was assessed by cell counting kit-8 (CCK-8) assay and colony formation assay. Flow cytometry assay was applied to determine cell cycle apoptosis. Cell migration and invasion were assessed using transwell assay. The potential relationship between miR-146a-5p and circ_0020123 or EIF4G2 was ascertained by dual-luciferase reporter assay and RIP assay. The role of circ_0020123 in vivo was explored by xenograft assay.

RESULTS

Circ_0020123 was upregulated in NSCLC, and circ_0020123 knockdown repressed proliferation, migration, and invasion of NSCLC cells. Circ_0020123 targeted miR-146a-5p, and miR-146a-5p inhibitor reversed the effects of circ_0020123 knockdown on NSCLC cells. In addition, miR-146a-5p suppressed cell proliferation, migration, and invasion by targeting EIF4G2. Moreover, the antitumor role of circ_0020123 knockdown was verified in vivo.

CONCLUSION

Knockdown of circ_0020123 inhibited NSCLC cell progression and tumor growth by targeting the miR-146a-5p/EIF4G2 axis.

CircDENND2D Inhibits PD-L1-Mediated Non-Small Cell Lung Cancer Metastasis and Immune Escape by Regulating miR-130b-3p/STK11 Axis

Local recurrence and distant metastasis of non-small cell lung cancer (NSCLC) caused by immune escape is one of the root causes of treatment difficulties. We aim to investigate the mechanism of immune escape in NSCLC. NSCLC tissues were collected. Cell proliferation was detected by CCK-8 assay. Cell migration and invasion ability was measured by Transwell assay. The expressions of E-cadherin, N-cadherin and PD-L1 were detected by Western blot. NSCLC cells were co-cultured with CD8+ T cells to simulate tumor microenvironment in vitro. The proportion of CD8+ T cells and apoptosis were detected by flow cytometry. Dual-luciferase reporter gene assay confirmed the targeting relationship of circDENND2D and STK11. The expressions of circDENND2D and STK1 were down-regulated, while miR-130b-3p expression was up-regulated in NSCLC tissues. Overexpression of circDENND2D or STK11 inhibited NSCLC cells proliferation, migration and invasion, and attenuated the immune escape of NSCLC cells. CircDENND2D targeted miR-130b-3p to competitively promote STK11 expression. STK11 knockdown or miR-130b-3p overexpression attenuated the function of circDENND2D overexpression on NSCLC cells. CircDENND2D inhibited metastasis and immune escape of NSCLC by regulating miR-130b-3p/STK11 axis.

N6 -methyladenosine-modified circFUT8 competitively interacts with YTHDF2 and miR-186-5p to stabilize FUT8 mRNA to promote malignant progression in lung adenocarcinoma

BACKGROUND

Lung cancer is the leading cause of cancer related to mortality worldwide, and the main pathological type is lung adenocarcinoma (LUAD). Circular RNAs (circRNAs) have been reported to be modified by N6 -methyladenosine (m6A), which is involved in the progression of diverse tumors. However, the crosstalk between circRNAs and m6A modification has not been well elucidated in LUAD.

METHODS

MeRIP-seq and YTHDF2-RIP-seq datasets were explored to identify candidate circRNAs modified by YTHDF2. Dual-luciferase reporter assay, RIP, and rescue assays were performed to explore the relationship between circFUT8 and its parent mRNA of FUT8. In vitro and in vivo experiments were utilized to uncover the function of circFUT8.

RESULTS

In this study, we identified a novel m6A-modified circFUT8, derived from exon 3 of FUT8, which was elevated in tumor tissues compared with adjacent noncancerous tissues. The m6A reader YTHDF2 recognized and destabilized circFUT8 in an m6A-dependent manner. YTHDF2 also combined with the line form of FUT8 (mFUT8), and circFUT8 competitively interacted with YTHDF2, blunting its binding to mFUT8, to stabilize the mRNA level of FUT8. Additionally, circFUT8 sponged miR-186-5p to elevate the expression of mFUT8. Finally, we revealed that circFUT8 promoted the malignant progression of LUAD dependent on the oncogenic function of FUT8.

CONCLUSIONS

These findings identified a novel m6A-modified circFUT8 recognized and destabilized by YTHDF2, which competitively interacted with YTHDF2 and miR-186-5p to stabilize FUT8 mRNA to promote malignant progression in LUAD.

Network module analysis and molecular docking-based study on the mechanism of astragali radix against non-small cell lung cancer

BACKGROUND

Most lung cancer patients worldwide (stage IV non-small cell lung cancer, NSCLC) have a poor survival: 25%-30% patients die < 3 months. Yet, of those surviving > 3 months, 10%-15% patients survive (very) long. Astragali radix (AR) is an effective traditional Chinese medicine widely used for non-small cell lung cancer (NSCLC). However, the pharmacological mechanisms of AR on NSCLC remain to be elucidated.

METHODS

Ultra Performance Liquid Chromatography system coupled with Q-Orbitrap HRMS (UPLC-Q-Orbitrap HRMS) was performed for the qualitative analysis of AR components. Then, network module analysis and molecular docking-based approach was conducted to explore underlying mechanisms of AR on NSCLC. The target genes of AR were obtained from four databases including TCMSP (Traditional Chinese Medicine Systems Pharmacology) database, ETCM (The Encyclopedia of TCM) database, HERB (A high-throughput experiment- and reference-guided database of TCM) database and BATMAN-TCM (a Bioinformatics Analysis Tool for Molecular mechanism of TCM) database. NSCLC related genes were screened by GEO (Gene Expression Omnibus) database. The STRING database was used for protein interaction network construction (PIN) of AR-NSCLC shared target genes. The critical PIN were further constructed based on the topological properties of network nodes. Afterwards the hub genes and network modules were analyzed, and enrichment analysis were employed by the R package clusterProfiler. The Autodock Vina was utilized for molecular docking, and the Gromacs was utilized for molecular dynamics simulations Furthermore, the survival analysis was performed based on TCGA (The Cancer Genome Atlas) database.

RESULTS

Seventy-seven AR components absorbed in blood were obtained. The critical network was constructed with 1447 nodes and 28,890 edges. Based on topological analysis, 6 hub target genes and 7 functional modules were gained. were obtained including TP53, SRC, UBC, CTNNB1, EP300, and RELA. After module analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that AR may exert therapeutic effects on NSCLC by regulating JAK-STAT signaling pathway, PI3K-AKT signaling pathway, ErbB signaling pathway, as well as NFkB signaling pathway. After the intersection calculation of the hub targets and the proteins participated in the above pathways, TP53, SRC, EP300, and RELA were obtained. These proteins had good docking affinity with astragaloside IV. Furthermore, RELA was associated with poor prognosis of NSCLC patients.

CONCLUSIONS

This study could provide chemical component information references for further researches. The potential pharmacological mechanisms of AR on NSCLC were elucidated, promoting the clinical application of AR in treating NSCLC. RELA was selected as a promising candidate biomarker affecting the prognosis of NSCLC patients.

hsa_circ_0000519 promotes the progression of lung adenocarcinoma through the hsa-miR-1296-5p/DARS axis

Emerging research indicates that circRNAs serve a crucial role in occurrence and development of cancers. This study aimed to uncover the biological role of hsa_circ_0000519 in the progression of LUAD (lung adenocarcinoma). hsa_circ_0000519 was identified by bioinformatic analysis, and its differential expression was validated in LUAD tissues and cell lines. CCK8, colony formation, wound healing, transwell assays, and xenograft tumor models were used to observe the biological functions of hsa_circ_0000519. FISH, RIP, dual luciferase reporter assays, and recovery experiments were implemented to explore the underlying mechanisms of hsa_circ_0000519. hsa_circ_0000519 was significantly upregulated in LUAD tissues and cell lines. The expression of hsa_circ_0000519 was positively correlated with T grade and TNM stage in patients with LUAD. Downregulation of hsa_circ_0000519 remarkably reduced cell proliferation, migration, invasion in vitro, and tumor growth in vivo. Mechanistic investigation demonstrated that hsa_circ_0000519 directly sponged hsa-miR-1296-5p to reduce its repressive impact on DARS as well as activate the PI3K/AKT/mTOR signaling pathway. The malignant phenotypes of LUAD cells induced by upregulation of hsa_circ_0000519 could be rescued by hsa-miR-1296-5p overexpression or knockdown of DARS. In conclusion, hsa_circ_0000519 promotes LUAD progression through the hsa-miR-1296-5p/DARS axis and may be expected as a novel biomarker and therapeutic for LUAD.

miR-330-3p alleviates the progression of atherosclerosis by downregulating AQP9

Atherosclerosis (AS) is the main cause of cardiovascular diseases. However, the role of AQP9 in AS is not well understood. In the present study, we predicted that miR-330-3p might regulate AQP9 in AS through bioinformatics analysis, and we established AS model using ApoE^-/- mouse (C57BL/6) with high-fat diet (HFD). Hematoxylin and eosin (H&E) and Oil red O staining were used to determine atherosclerotic lesions. CCK8 and Ethyny1-2-deoxyuridine (EdU) assays were used to investigate human umbilical vein endothelial cells (HUVECs) proliferation after treatment with 100 μg/mL ox-LDL. Wound scratch healing and transwell assays were used to measure the cell invasion and migration ability. Flow cytometry assay was used to determine apoptosis and cell cycle. A dual-luciferase reporter assay was performed to investigate the binding of miR-330-3p and AQP9. We identified that the expression of miR-330-3p in AS mice model decreased while the expression level of AQP9 increased. miR-330-3p overexpression or down-regulation of AQP9 could reduce cell apoptosis, promote cell proliferation, and migration after ox-LDL treatment. Dual-luciferase reporter assay result presented that AQP9 was directly inhibited by miR-330-3p. These results suggest that miR-330-3p inhibits AS by regulating AQP9. miR-330-3p/AQP9 axis may be a new therapeutic target for AS.

Long noncoding RNA FGD5-AS1 alleviates childhood IgA nephropathy by targeting PTEN-mediated JNK/c-Jun signaling pathway via miR-196b-5p

This paper studied lncRNA FGD5 antisense RNA 1 (FGD5-AS1)-associated mechanisms in immunoglobulin A nephropathy (IgAN). FGD5-AS1, miR-196b-5p, and PTEN in the serum of children with IgAN were assessed. MES-13 cells were stimulated by p-IgA1 to construct an in vitro model of IgAN. After plasmid intervention, cell proliferation, cell cycle, apoptosis, and inflammatory response were correspondingly evaluated. An IgAN mouse model was established to define FGD5-AS1/miR-196b-5p/PTEN axis-mediated alternations of 24-h proteinuria, blood urea nitrogen, serum creatinine, glomerular IgA deposition, renal fibrosis, and glycogen content in renal tissue. The changes in JNK/c-Jun pathway activation in the cell model were also tested. Our results discovered that FGD5-AS1 and PTEN were down-regulated and miR-196b-5p was up-regulated in children with IgAN. Overexpression of FGD5-AS1 or silencing of miR-196b-5p impeded the proliferation and inflammatory response and induced apoptosis of p-IgA1-stimulated MES-13 cells, and improved pathological conditions in IgAN mice. Inhibition of PTEN rescued the therapeutic effects of overexpression of FGD5-AS1 or inhibition of miR-196b-5p on IgAN. FGD5-AS1/miR-196b-5p/PTEN axis inhibited the activation of the JNK/c-Jun pathway. Taken together, FGD5-AS1 attenuates IgAN by targeting PTEN-mediated JNK/c-Jun signaling via miR-196b-5p. Therefore, FGD5-AS1 may be a new therapeutic target for IgAN.

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.

Circ_0006220 Contributes to NSCLC Progression through miR-342-3p/GOT2 Axis

PURPOSE

Dysregulated circular RNAs (circRNAs) have shown crucial modulatory functions in tumorigenesis, containing non-small cell lung cancer (NSCLC). The purpose of this study was to explore the biological functions and regulatory theory of circ_0006220 in NSCLC.

METHODS

Reverse transcription-quantitative polymerase chain reaction and Western blot assay were conducted to measure RNA and protein expression, respectively. A total of 73 cases of NSCLC tumor samples were collected for expression analysis, and A-549 and NCI-H1299 cell lines were used for functional experiments. Cell proliferation was assessed by cell counting kit-8 assay, colony formation assay, 5-ethynyl-2'-deoxyuridine assay, and flow cytometry. Cell apoptosis, motility, and angiogenesis ability were analyzed by flow cytometry, transwell assays, and capillary-like network formation assay. Dual-luciferase reporter assay and RNA immunoprecipitation assay were conducted to verify the target relationships.

RESULTS

Circ_0006220 was highly expressed in NSCLC tissues and cell lines. Circ_0006220 silencing inhibited the proliferation, migration, invasion, and angiogenesis but induced the apoptosis of NSCLC cells. Circ_0006220 acted as a microRNA-342-3p (miR-342-3p) sponge, and circ_0006220 knockdown-induced changes on the phenotypes of NSCLC cells were largely overturned by the knockdown of miR-342-3p. miR-342-3p interacted with the 3' untranslated region of glutamic-oxaloacetic transaminase 2 (GOT2), and GOT2 overexpression largely diminished miR-342-3p overexpression-mediated influences in NSCLC cells. Circ_0006220 could up-regulate GOT2 expression by sponging miR-342-3p.

CONCLUSION

Circ_0006220 promoted the malignant behaviors of NSCLC cells through mediating the miR-342-3p/GOT2 regulation cascade.

Circ-HSP90A expedites cell growth, stemness, and immune evasion in non-small cell lung cancer by regulating STAT3 signaling and PD-1/PD-L1 checkpoint

BACKGROUND

Circular RNAs (circRNAs) are important participators in tumor progression for their stable structure and high tissue-specific expression. The purpose of this research was to clarify the potential and mechanism of a novel circRNA-circ-HSP90A in non-small cell lung cancer (NSCLC).

METHODS

Biological potentials of circ-HSP90A in NSCLC were measured by functional assays. Molecular interaction was assessed by bioinformatics analysis and mechanical assays.

RESULTS

Results depicted that circ-HSP90A was cyclization from its host gene heat shock protein 90 alpha (HSP90A) and was up-regulated in NSCLC cells. Circ-HSP90A depletion retarded proliferation, migration, invasion, and immune evasion. Mechanistically, circ-HSP90A recruited ubiquitin specific peptidase 30 (USP30) to stabilize HSP90A and then stimulated the signal transducer and activator of transcription 3 (STAT3) signaling. Meanwhile, circ-HSP90A sponged miR-424-5p to programmed cell death ligand 1 (PD-L1).

CONCLUSIONS

Our study firstly showed that circ-HSP90A promoted cell growth, stemness, and immune evasion in NSCLC through regulating STAT3 signaling and programmed cell death 1 (PD-1)/PD-L1 checkpoint, mirroring that targeting circ-HSP90A might become a novel target of immunotherapy in NSCLC.

Circ_0058608 contributes to the progression and taxol resistance of non-small cell lung cancer by sponging miR-1299 to upregulate GBP1

Circular RNAs (circRNAs) act as key regulators in human cancers and chemoresistance. Here, we aimed to explore the role and mechanism of circ_0058608 in nonsmall cell lung cancer (NSCLC) and taxol resistance. The expression of circ_0058608, microRNA-1299 (miR-1299) and guanylate binding protein 1 (GBP1) mRNA was determined by quantitative real-time PCR. In-vitro and in-vivo assays were conducted using Cell Counting Kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), colony formation, transwell assays, flow cytometry and animal xenograft experiments. The interaction between miR-1299 and circ_0058608 or GBP1 was confirmed by the dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. Circ_0058608 was overexpressed in NSCLC tissues/cells and taxol-resistant NSCLC tissues/cells. Circ_0058608 knockdown inhibited NSCLC cell proliferation and metastasis and also suppressed tumor growth in vivo. Moreover, circ_0058608 knockdown increased taxol sensitivity by increasing taxol-induced apoptosis in taxol-resistant NSCLC cells. Moreover, circ_0058608 silencing enhanced taxol-induced tumor growth of NSCLC in vivo. MiR-1299 was a target of circ_0058608, and the effects of circ_0058608 knockdown on NSCLC cell progression and taxol resistance were reversed by miR-1299 inhibition. Additionally, miR-1299 could interact with GBP1, and miR-1299 suppressed NSCLC cell progression and taxol resistance by targeting GBP1. Furthermore, circ_0058608 could regulate GBP1 expression by sponging miR-1299. Circ_0058608 promoted the progression and taxol resistance of NSCLC by regulating the miR-1299/GBP1 axis.

CircRNA High Mobility Group At-hook 2 regulates cell proliferation, metastasis and glycolytic metabolism of nonsmall cell lung cancer by targeting miR-331-3p to upregulate High Mobility Group At-hook 2

Increasing circular RNAs (circRNAs) have been identified as pivotal players in nonsmall cell lung cancer (NSCLC). The study will explore the function and mechanism of circRNA High Mobility Group AT-hook 2 (circHMGA2) in NSCLC. The circHMGA2, microRNA-331-3p (miR-331-3p) and HMGA2 expression analyses were performed via quantitative real-time PCR. Cell proliferation was assessed via Cell Counting Kit-8 and colony formation assays. Transwell migration/invasion assays were used for measuring cell metastasis. Glucose consumption and lactate production were determined for glycolytic evaluation. Western blot was used to detect the protein expression of HMGA2 and glycolytic markers. Target analysis was performed by dual-luciferase reporter, RNA immunoprecipitation and RNA pull-down assays. Xenograft tumor assay in mice was conducted for the investigation of circHMGA2 in vivo . CircHMGA2 was overexpressed in NSCLC, and high circHMGA2 level might be related to NSCLC metastasis and poor prognosis. In-vitro assays suggested that NSCLC cell growth, metastasis and glycolysis were retarded by downregulation of circHMGA2. Upregulation of HMGA2 was shown to return the anticancer response of circHMGA2 knockdown in NSCLC cells. Through interacting with miR-331-3p, circHMGA2 could regulate the expression of HMGA2. In addition, circHMGA2/miR-331-3p and miR-331-3p/HMGA2 axes were affirmed in NSCLC regulation. In-vivo analysis indicated that circHMGA2 inhibition also reduced tumorigenesis and glycolysis of NSCLC via the miR-331-3p/HMGA2 axis. This study disclosed the oncogenic role of circHMGA2 and the regulatory circHMGA2/miR-331-3p/HMGA2 axis in NSCLC.

Lysine demethylase 5A promotes prostate adenocarcinoma progression by suppressing microRNA-330-3p expression and activating the COPB2/PI3K/AKT axis in an ETS1-dependent manner

Lysine demethylase 5A (KDM5A) is a histone demethylase frequently involved in cancer progression. This research aimed to explore the function of KDM5A in prostate adenocarcinoma (PRAD) and the molecular mechanism. KDM5A was highly expressed in collected PRAD tissues and acquired PRAD cells. High KDM5A expression was correlated with reduced survival and poor prognosis of patients with PRAD. Knockdown of KDM5A suppressed the proliferation, colony formation, migration, and invasiveness of PRAD cells and reduced angiogenesis ability of endothelial cells. Downstream molecules implicated in KDM5A mediation were predicted using integrated bioinformatic analyses. KDM5A enhanced ETS proto-oncogene 1 (ETS1) expression through demethylation of H3K4me2 at its promoter. ETS1 suppressed the transcription activity of miR-330-3p, and either further ETS1 overexpression or miR-330-3p inhibition blocked the functions of KDM5A knockdown in PRAD. miR-330-3p targeted coatomer protein complex subunit β2 (COPB2) mRNA. Downregulation of miR-330-3p restored the expression of COPB2 and activated the PI3K/AKT pathway in PRAD. The results in vitro were reproduced in vivo where KDM5A downregulation suppressed the growth and metastasis of xenograft tumors in nude mice. In conclusion, this study demonstrated that KDM5A promoted PRAD by suppressing miR-330-3p and activating the COPB2/PI3K/AKT axis in an ETS1-dependent manner.

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.

Circ_0006404 enhances hepatocellular carcinoma progression by regulating miR-624

Growing studies have demonstrated that circRNAs (circular RNAs) act potential roles in tumor metastasis and progression. However, the expression and function of circ_0006404 in hepatocellular carcinoma (HCC) remain to be investigated. The expression of circ_0006404 and miR-624 was detected by qRT-PCR. CCK-8 assay, flow cytometry, and wound healing were performed to determine cell proliferation, cycle, and migration. The target of circ_0006404 was studied by bioinformatics and luciferase activity analysis. Our data indicated that circ_0006404 was overexpressed in HCC specimens and cells and ectopic expression of circ_0006404 increased HCC cell growth, cycle, and migration. Moreover, we showed that miR-624 was downregulated in HCC specimens and cells and miR-624 expression was negatively correlated with circ_0006404 expression in HCC specimens. Circ_0006404 sponged miR-624 in HCC cell, and the overexpression of circ_0006404 suppressed miR-624 expression in HCC cell. Furthermore, circ_0006404 induced HCC cell growth, cycle, and migration via regulating miR-624. These results elucidated that circ_0006404 facilitated HCC progression and might act as one new biomarker for this carcinoma.

Integration of TE Induces Cancer Specific Alternative Splicing Events

Alternative splicing of messenger RNA (mRNA) precursors contributes to genetic diversity by generating structurally and functionally distinct transcripts. In a disease state, alternative splicing promotes incidence and development of several cancer types through regulation of cancer-related biological processes. Transposable elements (TEs), having the genetic ability to jump to other regions of the genome, can bring about alternative splicing events in cancer. TEs can integrate into the genome, mostly in the intronic regions, and induce cancer-specific alternative splicing by adjusting various mechanisms, such as exonization, providing splicing donor/acceptor sites, alternative regulatory sequences or stop codons, and driving exon disruption or epigenetic regulation. Moreover, TEs can produce microRNAs (miRNAs) that control the proportion of transcripts by repressing translation or stimulating the degradation of transcripts at the post-transcriptional level. Notably, TE insertion creates a cancer-friendly environment by controlling the overall process of gene expression before and after transcription in cancer cells. This review emphasizes the correlative interaction between alternative splicing by TE integration and cancer-associated biological processes, suggesting a macroscopic mechanism controlling alternative splicing by TE insertion in cancer.

MALAT1-miRNAs network regulate thymidylate synthase and affect 5FU-based chemotherapy

Background

The active metabolite of 5-Fluorouracil (5FU), used in the treatment of several types of cancer, acts by inhibiting the thymidylate synthase encoded by the TYMS gene, which catalyzes the rate-limiting step in DNA replication. The major failure of 5FU-based cancer therapy is the development of drug resistance. High levels of TYMS-encoded protein in cancerous tissues are predictive of poor response to 5FU treatment. Expression of TYMS is regulated by various mechanisms, including involving non-coding RNAs, both miRNAs and long non-coding RNAs (lncRNAs).

Aim

To delineate the miRNAs and lncRNAs network regulating the level of TYMS-encoded protein.

Main body

Several miRNAs targeting TYMS mRNA have been identified in colon cancers, the levels of which can be regulated to varying degrees by lncRNAs. Due to their regulation by the MALAT1 lncRNA, these miRNAs can be divided into three groups: (1) miR-197-3p, miR-203a-3p, miR-375-3p which are downregulated by MALAT1 as confirmed experimentally and the levels of these miRNAs are actually reduced in colon and gastric cancers; (2) miR-140-3p, miR-330-3p that could potentially interact with MALAT1, but not yet supported by experimental results; (3) miR-192-5p, miR-215-5p whose seed sequences do not recognize complementary response elements within MALAT1. Considering the putative MALAT1-miRNAs interaction network, attention is drawn to the potential positive feedback loop causing increased expression of MALAT1 in colon cancer and hepatocellular carcinoma, where YAP1 acts as a transcriptional co-factor which, by binding to the TCF4 transcription factor/ β-catenin complex, may increase the activation of the MALAT1 gene whereas the MALAT1 lncRNA can inhibit miR-375-3p which in turn targets YAP1 mRNA.

Conclusion

The network of non-coding RNAs may reduce the sensitivity of cancer cells to 5FU treatment by upregulating the level of thymidylate synthase.

The homeostatic malfunction of a novel feedback pathway formed by lncRNA021545, miR-330-3p and epiregulin contributes in hepatocarcinoma progression via mediating epithelial-mesenchymal transition

A better understanding of tumor metastasis is urgently required for the treatment and prognosis of hepatocarcinoma patients. Current work contributes a novel ceRNA feedback regulation pathway composed of epiregulin (EREG), microRNA-330-3p (miR-330-3p) and long non-coding RNA 021545 (lncRNA021545) in regulating hepatocarcinoma malignancy via epithelial-mesenchymal transition (EMT) process. Closely correlated, the deficiencies of EREG and lncRNA021545 and the overexpression of miR-330-3p were involved in the clinical progression of hepatocarcinoma. In vitro results showed that 1) lncRNA021545 downregulation promoted, 2) miR-330-3p dysexpression positively correlated, and 3) EREG dysexpression reversely correlated with the migratory and invasive properties of hepatocarcinoma HCCLM3 and Huh7 cell lines. By directly binding to EREG and lncRNA021545, miR-330-3p expression change reversely correlated with their expressions in HCCLM3 and Huh7 cells, which was also confirmed in primary tumors from HCCLM3-xenograft mice in responding to miR-330-3p change. LncRNA021545 and EREG positively regulated each other, and lncRNA021545 negatively regulated miR-330-3p, while, EREG dysregulation unchanged miR-330-3p expression in hepatocarcinoma cells. Furthermore, systemic in vitro cellular characterizations showed that the malfunctions of the three molecules mediated the invasiveness of hepatocarcinoma cells via EMT process through affecting the expressions of E-cadherin, N-cadherin, vimentin, snail and slug, which was further confirmed by in vivo miR-330-3p promotion on the tumorigenicity and metastasis of HCCLM3 bearing nude mice and by in vitro miR-330-3p promotion on the migration and invasion of hepatocarcinoma cells to be antagonized by EREG overexpression through acting on EMT process. Our work indicates, that by forming a circuit signaling feedback pathway, the homeostatic expressions of lncRNA021545, miR-330-3p and EREG are important in liver health. Its collapse resulted from the downregulations of lncRNA021545 and EREG together with miR-330-3p overexpression promote hepatocarcinoma progression by enhancing the invasiveness of tumor cells through EMT activation. These discoveries suggest that miR-330-3p/lncRNA021545/EREG axis plays a critical role in hepatocarcinoma progression and as a candidate for its treatment.

Long-noncoding RNA HOXA transcript at the distal tip ameliorates the insulin resistance and hepatic gluconeogenesis in mice with gestational diabetes mellitus via the microRNA-423-5p/wingless-type MMTV integration site family member 7A axis

Long-noncoding RNA HOXA transcript at the distal tip (HOTTIP) has been probed to exert essential effects on diabetes progression, while its function in gestational diabetes mellitus (GDM) remains unclear. This study was committed to unravel the effects of HOTTIP on GDM progression via the microRNA (miR)-423-5p/wingless-type MMTV integration site family member 7A (WNT7A) axis. The GDM mouse model was established. HOTTIP, miR-423-5p and WNT7A levels in GDM mice were examined. The saline with dissolved various constructs altering HOTTIP, miR-423-5p and WNT7A expression was injected into GDM mice to detect the levels of GDM‐related biochemical indices, HOMA indices, liver gluconease: expression levels of phosphoenolpyruvate carboxykinase (PEPCK), glucose-6-phosphatase (G-6-Pase), glucose transporter 2 (GLUT2) and pathological changes of pancreatic tissues, and the apoptosis rate of pancreatic cells in GDM mice. The relations among HOTTIP, miR-423-5p and WNT7A were validated. HOTTIP and WNT7A levels were decreased while miR-423-5p was elevated in GDM mice. The enriched HOTTIP or silenced miR-423-5p alleviated the levels of GDM‐relatedbiochemical indices, enhanced the insulin homeostasis, elevated GLUT2 expression and decreased G-6-pase and PEPCK expression, mitigated the pathological changes of pancreatic tissues, and hindered the apoptosis of pancreatic cells. MiR-143-5p upregulation abrogated the effects of elevated HOTTIP on repressing GDM; whereas WNT7A deletion reversed the therapeutic effects of reduced miR-423-5p. HOTTIP sponged miR-423-5p that targeted WNT7A. HOTTIP ameliorates insulin resistance and hepatic gluconeogenesis in GDM mice via the modulation of the miR-423-5p/WNT7A axis. This study affords novel therapeutic modalities for GDM treatment.

Circular RNA_0078767 upregulates Kruppel-like factor 9 expression by targeting microRNA-889, thereby inhibiting the progression of osteosarcoma

Among kids and juveniles, osteosarcoma (OS) is a common bone malignancy. Circular RNAs (circs, circRNAs) play important roles in multiple malignancies including OS, yet circ_0078767ʹs biological functions in OS are far from well elucidated. This study is targeted at understanding circ_0078767ʹs biological functions in OS and its molecular mechanisms. This study confirmed that circ_0078767 expression was reduced in OS cell lines and tissues. Circ_0078767 overexpression remarkably inhibited OS cell growth, migration, invasion, epithelial-mesenchymal transition (EMT), and promoted apoptosis, whereas circ_0078767 knockdown resulted in the opposite effects. MicroRNA-889 (miR-889) was targeted and regulated by circ_0078767, and miR-889 could negatively modulate Kruppel-like factor 9 (KLF9) expression. Besides, circ_0078767 positively regulated KLF9 expression in OS cells via repressing miR-889. In conclusion, circ_0078767 enhances KLF9 expression by targeting miR-889 to inhibit OS progression.

Circular RNA (circ)_0129047 upregulates bone morphogenetic protein receptor type 2 expression to inhibit lung adenocarcinoma progression by sponging microRNA (miR)-1206

Circular RNAs (circRNAs) play significant roles in the tumorigenesis and progression of various cancers, including lung adenocarcinoma (LAC). However, their underlying biological functions in LAC remain unclear. Here, we investigated the tumor suppressor role of the newly identified circRNA, circ_0129047, in LAC tumorigenesis and progression. The expression levels of circ_0129047, microRNA (miR)-1206, and bone morphogenetic protein receptor type 2 (BMPR2) mRNA in LAC cells and tissues were monitored using reverse transcription-quantitative polymerase chain reaction. Dual-luciferase reporter, RNA immunoprecipitation, and RNA pull-down assays were used to confirm the targeting relationships among circ_0129047, miR-1206, and BMPR2 mRNA. Functional experiments for A549 and PC9 cells were performed using cell counting kit-8, bromodeoxyuridine enzyme-linked immunosorbent, caspase-3 activity, cell adhesion, wound healing, and transwell assays. Circ_0129047 expression levels were reduced in LAC cells and tissues. Mechanistically, we discovered that circ_0129047 could sponge miR-1206, and miR-1206 could directly target BMPR2. In addition, circ_0129047 or BMPR2 knockdown facilitated the viability, proliferation, adhesion, migration, and invasion, while inhibiting the apoptosis of LAC cells. Furthermore, the inhibitory effects of circ_0129047 or BMPR2 overexpression on the malignant phenotype of LAC cells could be reversed by the overexpression of miR-1206. In conclusion, circ _0129047 was found to play a tumor suppressive role in LAC progression; it upregulated BMPR2 expression to inhibit LAC progression by sponging miR-1206.

Abbreviations: non-small cell lung cancer (NSCLC); small cell lung cancer (SCLC); lung adenocarcinoma (LAC); Circular RNA (circRNA); MicroRNA (miRNA); bone morphogenetic protein (BMP); squamous cell lung cancer (SCC); RNA immunoprecipitation (RIP)

Circular RNA_0120376 regulates microRNA-148b-3 and centrosomal protein 55 to promote non-small cell lung cancer development

Circular RNAs (circRNAs) are non-coding RNAs with covalent closed-loop structures that are vital in regulating diverse pathological processes. This work is aimed to investigate the role of circ_0120376 in non-small cell lung cancer (NSCLC). Circ_0120376, microRNA (miR)-148b-3p, and centrosomal protein 55 (CEP55) mRNA expression in NSCLC tissues and cells were determined using qRT-PCR. The influences of circ_0120376 and miR-148b-3p on the proliferation of NSCLC cell lines were analyzed by CCK-8 and colony formation assays. Apoptosis was analyzed by flow cytometry. Cell migration and invasion were analyzed using the Transwell experiment. Binding relationships between circ_0120376 and miR-148b-3p and between miR-148b-3p and CEP55 3'UTR were investigated using the dual-luciferase reporter experiment and the RIP experiment. Western blot was conducted to analyze the regulatory effect of circ_0120376 and miR-148b-3p on CEP55 expression. We found that circ_0120376 was markedly overexpressed in NSCLC, and its overexpression was positively associated with increased T stage and lymph node metastasis of the patients. Functional experiments unveiled that circ_0120376 enhanced the proliferation, migration and invasion of NSCLC cells and impeded apoptosis, while knocking down circ_0120376 remarkably suppressed the malignant features of NSCLC cells mentioned above. Circ_0120376 could adsorb miR-148b-3p to reduce miR-148b-3p expression, and circ_0120376 could increase CEP55 expression via adsorbing miR-148b-3p. In summary, circ_0120376 contributes to the malignancy of NSCLC cells through a ceRNA mechanism via regulating miR-148b-3p/CEP55 axis. Circ_0120376 is likely to be a potential diagnostic biomarker and therapeutic target for NSCLC.

Regulation of RASSF by non-coding RNAs in different cancers

Ras-association domain family (RASSF) proteins are tumor suppressors and have gained phenomenal limelight because of their mechanistic role in the prevention/inhibition of carcinogenesis and metastasis. Decades of research have demystified wide ranging activities of RASSF molecules in multiple stages of cancers. Although major fraction of RASSF molecules has tumor suppressive roles, yet there is parallel existence of proof-of-concept about moonlighting activities of RASSF proteins as oncogenes. RASSF proteins tactfully rewire signaling cascades for prevention of cancer and metastasis but circumstantial evidence also illuminates oncogenic role of different RASSF proteins in different cancers. In this review we have attempted to provide readers an overview of the complex interplay between non-coding RNAs and RASSF proteins and how these versatile regulators shape the landscape of carcinogenesis and metastasis.

Circular RNA hsa_circ_0011298 enhances Taxol resistance of non-small cell lung cancer by regulating miR-486-3p/CRABP2 axis

Background

Circular RNAs (circRNAs) serve as critical regulators in the chemoresistance of human cancers, including non‐small cell lung cancer (NSCLC). We aimed to explore the role of hsa_circ_0011298 (circ_0011298) and its mechanism in Taxol resistance of NSCLC.

Methods

Circ_0011298, microRNA‐486‐3p (miR‐486‐3p), and CRABP2 mRNA expression were determined using qRT‐PCR. EdU and MTT assays were used to detect cell proliferation. Cell cycle distribution and cell apoptosis were detected by flow cytometry. Cell migratory and invasive abilities were detected using transwell assay. Cellular glycolysis was determined by specific kits. Protein levels were examined by western blot. Dual‐luciferase reporter and RIP assays were performed to confirm the relationship between miR‐486‐3p and circ_0011298 or CRABP2. Xenograft mice model was established to confirm the function of circ_0011298 in vivo.

Results

Circ_0011298 was overexpressed in Taxol‐resistant NSCLC cells and tissues. Circ_0011298 knockdown enhanced Taxol sensitivity by decreasing cell proliferation, migration, invasion, and glycolysis and inducing apoptosis and cell cycle arrest in Taxol‐resistant NSCLC cells. Circ_0011298 was a sponge of miR‐486‐3p, and the impact of circ_0011298 silencing on Taxol resistance was rescued by miR‐486‐3p inhibition. Moreover, miR‐486‐3p directly targeted CRABP2, and miR‐486‐3p inhibited Taxol resistance by targeting CRABP2. Furthermore, circ_0011298 regulated CRABP2 expression through targeting miR‐486‐3p. Importantly, circ_0011298 interference elevated Taxol sensitivity of NSCLC in vivo.

Conclusion

Circ_0011298 elevated Taxol resistance of NSCLC by sponging miR‐486‐3p and upregulating CRABP2, providing a possible circRNA‐targeted therapy for NSCLC.

Clinical Implications of Circulating Circular RNAs in Lung Cancer

Circular RNAs (circRNAs) are single-stranded RNAs with a covalently closed-loop structure that increases their stability; thus, they are more advantageous to use as liquid biopsy markers than linear RNAs. circRNAs are thought to be generated by back-splicing of pre-mRNA transcripts, which can be facilitated by reverse complementary sequences in the flanking introns and trans-acting factors, such as splicing regulatory factors and RNA-binding factors. circRNAs function as miRNA sponges, interact with target proteins, regulate the stability and translatability of other mRNAs, regulate gene expression, and produce microproteins. circRNAs are also found in the body fluids of cancer patients, including plasma, saliva, urine, and cerebrospinal fluid, and these “circulating circRNAs” can be used as cancer biomarkers. In lung cancer, some circulating circRNAs have been reported to regulate cancer progression and drug resistance. Circulating circRNAs have significant diagnostic value and are associated with the prognosis of lung cancer patients. Owing to their functional versatility, heightened stability, and practical applicability, circulating circRNAs represent promising biomarkers for lung cancer diagnosis, prognosis, and treatment monitoring.

Circ_0020123 plays an oncogenic role in non-small cell lung cancer depending on the regulation of miR-512-3p/CORO1C

Background

Non‐small cell lung cancer (NSCLC) is one of the leading causes responsible for cancer‐associated death globally. The aim of this study was to illustrate the function of circular RNA_0020123 (circ_0020123) in NSCLC progression and its associated mechanism.

Methods

RNA and protein expression was determined by reverse transcription‐quantitative polymerase chain reaction (RT‐qPCR) and western blot assay. Cell proliferation, migration, invasion, angiogenesis, apoptosis and autophagy were analyzed to assess the role of circ_0020123/microRNA‐512‐3p (miR‐512‐3p)/coronin 1C (CORO1C) axis in NSCLC cells. Tumorigenesis in nude mice was analyzed to determine the in vivo role of circ_0020123. The intermolecular target relation was confirmed by dual‐luciferase reporter and RNA immunoprecipitation (RIP) assays.

Results

Circ_0020123 expression was aberrantly upregulated in NSCLC tissues and cell lines. Circ_0020123 interference markedly restrained cell proliferation, migration, invasion, angiogenesis and autophagy and induced cell apoptosis of NSCLC cells. Circ_0020123 knockdown suppressed xenograft tumor growth in vivo. Circ_0020123 acted as a molecular sponge for miR‐512‐3p. Circ_0020123 silencing‐induced effects in NSCLC cells were largely reversed by the knockdown of miR‐512‐3p. miR‐512‐3p interacted with the 3′ untranslated region (3′UTR) of CORO1C. CORO1C overexpression largely reversed miR‐512‐3p accumulation‐induced influences in NSCLC cells. Circ_0020123 positively regulated CORO1C expression by sponging miR‐512‐3p in NSCLC cells.

Conclusion

Circ_0020123 aggravated NSCLC progression by binding to miR‐512‐3p to induce CORO1C expression, which provided new potential targets for the treatment of NSCLC.

Circ_0078767 Inhibits the Progression of Non-Small-Cell Lung Cancer by Regulating the GPX3 Expression by Adsorbing miR-665

Non-small-cell lung cancer (NSCLC) is one of the most serious cancers. The circular RNA_0078767 (circ_0078767) expression was decreased in NSCLC tissues. However, the molecular mechanism of circ_0078767 remains unknown. The expression of circ_0078767, microRNA-665 (miR-665), and glutathione peroxidase 3 (GPX3) was detected by quantitative real-time fluorescence polymerase chain reaction (qRT-PCR). Cell proliferation, migration, and invasion were detected by colony formation assay and transwell assay, respectively. The lactate production and glucose consumption were tested by glycolysis. Western blot examined the protein levels of hexokinase-2 (HK2), matrix metalloproteinase-9 (MMP9), and GPX3 cells. Circinteractome predicted the relationship between miR-665 and circ_0078767 or GPX3 and was verified by dual luciferase reporter assays. The xenotransplantation model was established to study the role of circ_0078767 in vivo. The expression of circ_0078767 and GPX3 was decreased in NSCLC tissues, while the expression of miR-665 was increased. Circ_0078767 can sponge miR-665, and GPX3 is the target of miR-665. In vitro complement experiments showed that knockdown of circ_0078767 significantly promoted malignant behavior of NSCLC, while cotransfection of miR-665 inhibitor partially reduced this change. In addition, the GPX3 overexpression decreased the promoting effects of miR-665 upregulation on proliferation, migration, and invasion of NSCLC cells. Mechanically, circ_0078767 regulates the GPX3 expression in NSCLC cells by spongy miR-665. In addition, in vivo studies have shown that downregulation of circ_0078767 promotes tumor growth. Circ_0078767 silencing promotes proliferation, migration, invasion, and glycolysis of NSCLC cells by regulating the miR-665/GPX3 axis, suggesting that circ_0078767/miR-665/GPX3 axis may be a potential regulatory mechanism for the treatment of NSCLC.

Biogenesis, functions, and clinical implications of circular RNAs in non-small cell lung cancer

Lung cancer (LC) is the leading cause of cancer-related deaths worldwide, with high morbidity and mortality. Non-small cell lung cancer (NSCLC) is a major pathological type of LC and accounts for more than 80% of all cases. Circular RNAs (circRNAs) are a large class of non-coding RNAs (ncRNAs) with covalently closed-loop structures, a high abundance, and tissue-specific expression patterns. They participate in various pathophysiological processes by regulating complex gene networks involved in proliferation, apoptosis, migration, and epithelial-to-mesenchymal transition (EMT), as well as metastasis. A growing number of studies have revealed that the dysregulation of circRNAs contributes to many aspects of cancer progression, such as its occurrence, metastasis, and recurrence, suggesting their great potential as efficient and specific biomarkers in the diagnosis, prognosis, and therapeutic targeting of NSCLC. In this review, we systematically elucidate the characteristics, biogenesis, and functions of circRNAs and focus on their molecular mechanisms in NSCLC progression. Moreover, we highlight their clinical implications in NSCLC treatment.

Essential roles of exosome and circRNA_101093 on ferroptosis desensitization in lung adenocarcinoma

Background

Resistance to ferroptosis, a regulated cell death caused by iron‐dependent excessive accumulation of lipid peroxides, has recently been linked to lung adenocarcinoma (LUAD). Intracellular antioxidant systems are required for protection against ferroptosis. The purpose of the present study was to investigate whether and how extracellular system desensitizes LUAD cells to ferroptosis.

Methods

Established human lung fibroblasts MRC‐5, WI38, and human LUAD H1650, PC9, H1975, H358, A549, and H1299 cell lines, tumor and matched normal adjacent tissues of LUAD, and plasma from healthy individuals and LUAD patients were used in this study. Immunohistochemistry and immunoblotting were used to analyze protein expression, and quantitative reverse transcription‐PCR was used to analyze mRNA expression. Cell viability, cell death, and the lipid reactive oxygen species generation were measured to evaluate the responses to ferroptosis. Exosomes were observed using transmission electron microscope. The localization of arachidonic acid (AA) was detected using click chemistry labeling followed by confocal microscopy. Interactions between RNAs and proteins were detected using RNA pull‐down, RNA immunoprecipitation and photoactivatable ribonucleoside‐enhanced crosslinking and immunoprecipitation methods. Proteomic analysis was used to investigate RNA‐regulated proteins, and metabolomic analysis was performed to analyze metabolites. Cell‐derived xenograft, patient‐derived xenograft, cell‐implanted intrapulmonary LUAD mouse models and plasma/tissue specimens from LUAD patients were used to validate the molecular mechanism.

Results

Plasma exosome from LUAD patients specifically reduced lipid peroxidation and desensitized LUAD cells to ferroptosis. A potential explanation is that exosomal circRNA_101093 (cir93) maintained an elevation in intracellular cir93 in LUAD to modulate AA, a poly‐unsaturated fatty acid critical for ferroptosis‐associated increased peroxidation in the plasma membrane. Mechanistically, cir93 interacted with and increased fatty acid‐binding protein 3 (FABP3), which transported AA and facilitated its reaction with taurine. Thus, global AA was reduced, whereas N‐arachidonoyl taurine (NAT, the product of AA and taurine) was induced. Notably, the role of NAT in suppressing AA incorporation into the plasma membrane was also revealed. In pre‐clinical in vivo models, reducing exosome improved ferroptosis‐based treatment.

Conclusion

Exosome and cir93 are essential for desensitizing LUAD cells to ferroptosis, and blocking exosome may be helpful for future LUAD treatment.

Circ_0010235 facilitates lung cancer development and immune escape by regulating miR-636/PDL1 axis

Background

Circular RNAs (circRNAs) are a class of important regulators in various human cancers, including lung cancer. Here, we aimed to investigate the role of circ_0010235 in lung cancer.

Methods

The expression of circ_0010235, microRNA‐636 (miR‐636) and PDL1 was measured by quantitative real‐time PCR (qRT‐PCR). Cell proliferation was evaluated by CCK‐8, colony formation, and 5‐ethynyl‐2′‐deoxyuridine (EdU) assays. Cell apoptosis was detected by flow cytometry. Cell invasion was assessed by transwell assay. All protein levels were determined by western blot assay. In order to detect the roles of circ_0010235 in immune escape, lung cancer cells were cocultured with peripheral blood mononuclear cells (PBMCs) or cytokine‐induced killer (CIK) cells in vitro. The relationship between miR‐636 and circ_0010235 or PDL1 was verified by dual‐luciferase reporter assay and RNA pulldown assay. Immunohistochemistry (IHC) analysis was used to detect Ki67 and programmed death‐ligand 1 (PDL1) expression. A xenograft tumor model was established to verify the function of circ_0010235 in vivo.

Results

Circ_0010235 was overexpressed in lung cancer. Circ_0010235 knockdown inhibited proliferation, invasion and immune escape and promoted apoptosis of lung cancer cells. MiR‐636 was a target of circ_0010235, and miR‐636 inhibition reversed the effects of circ_0010235 knockdown in lung cancer cells. PDL1 was a direct target of miR‐636, and miR‐636 suppressed the proliferation and invasion and increased apoptosis and antitumor immunity in lung cancer cells by downregulating PDL1. Moreover, circ_0010235 positively regulated PDL1 expression by sponging miR‐636. Additionally, circ_0010235 knockdown hampered tumorigenesis in vivo.

Conclusion

Circ_0010235 knockdown inhibited lung cancer progression and increased antitumor immunity by regulating the miR‐636/PDL1 axis.

Hsa_circ_0134111 promotes intervertebral disc degeneration via sponging miR-578

Intervertebral disc degeneration (IDD) is a chronic degenerative and age-dependent process characterized by aberrant apoptosis, proliferation, synthesis, and catabolism of the extracellular matrix of the nucleus pulposus (NP) cells. Recently, studies showed that circular RNAs play important roles in the development of many diseases. However, the role of circRNAs in IDD development remains unknown. We showed that circ_0134111 level was overexpressed in IDD tissue samples as compar-ed to control tissues. The upregulation of circ_0134111 was more drastic in the moderate and severe IDD cases than in those with mild IDD. In addition, we showed that interleukin-1β and tumor necrosis factor-α exposure significantly enhanced circ_0134111 expression in NP cells. Furthermore, ectopic expression of circ_0134111 induced proliferation, pro-inflammatory cytokine secretion, and ECM degradation in the NP cells. We also showed that circ_0134111 directly interacted with microRNA (miR)-578 in NP cells where elevated expression of circ_0134111 enhanced the ADAMTS-5 and MMP-9 expression. Moreover, miR-578 expression was significantly decreased in IDD patients and the miR-578 expression was negatively correlated with circ_0134111 expression in the IDD samples. Interleukin-1β and tumor necrosis factor-α exposure significantly decreased miR-578 levels in NP cells, in which ectopic miR-578 expression inhibited cell growth, pro-inflammatory cytokine expression, and ECM degradation. Finally, we showed that circ_0134111 overexpression induced the IDD-related phenotypic changes through inhibiting miR-578. These data suggested that circ_0134111 could promote the progression of IDD through enhancing aberrant NP cell growth, inflammation, and ECM degradation partly via regulating miR-578.

An update on the roles of circular RNAs in spinal cord injury

Spinal cord injury (SCI) is a disabling condition for which therapeutic options are limited. Increasing number of microarray and next-generation sequencing studies have demonstrated that SCI coincides with altered expression of circular RNAs (circRNAs) in the damaged tissue. Emerging functional evidence further pinpointed specific differentially expressed circRNAs (e.g., circ-HIPK3, cicRNA.7079, circRNA_01477, circRNA-2960, and circ_0001723) for their effects on cellular processes relevant to SCI repair and regeneration, including neuronal apoptosis, astrocyte activation, and neuroinflammation, via sponging SCI-related microRNAs. Although circRNAs and their target microRNAs appear to be good candidates for therapeutic exploitation in SCI, further investigation into the efficient delivery of these regulatory molecules in a cell-type specific manner is a pre-requisite for translating these basic discoveries into clinical benefits.

Knockdown of circ-RAD23B inhibits non-small cell lung cancer progression via the miR-142-3p/MAP4K3 axis

Background

The development of non‐small cell lung cancer (NSCLC) is associated with the deregulation of circRNAs. The objective of this study was to investigate the effects of circ‐RAD23B in NSCLC.

Methods

Circ‐RAD23B expression, miR‐142‐3p and MAP4K3 was detected by qPCR. Cell proliferation was investigated by CCK‐8 assay and colony formation assay. Cell migration and invasion were assessed by transwell assay. Angiogenesis ability was assessed by tube formation assay. Cell cycle distribution and cell apoptosis were monitored by flow cytometry. The predicted binding relationship between miR‐142‐3p and circ‐RAD23B or MAP4K3 was verified by dual‐luciferase reporter assay. The protein level of MAP4K3 was detected by western blot. Animal models were established to determine the role of circ‐RAD23B in vivo.

Results

Circ‐RAD23B was shown to be upregulated in NSCLC tissues and cells. Knockdown of circ‐RAD23B inhibited proliferation, migration, invasion, angiogenesis and promoted cell cycle arrest and apoptosis in NSCLC cells, and circ‐RAD23B knockdown also impeded tumor growth in vivo. Circ‐RAD23B acted as miR‐142‐3p sponge to inhibit miR‐142‐3p expression and thus enrich the expression of MAP4K3, a target of miR‐142‐3p. Rescue experiments presented that miR‐142‐3p inhibition reversed the effects of circ‐RAD23B knockdown, and MAP4K3 overexpression abolished the effects of miR‐142‐3p restoration. In addition, we found that circ‐RAD23B knockdown led to decreased phosphorylation expression of ERK1/2, JNK and p38, three key groups of the MAPK signaling pathway.

Conclusions

Circ‐RAD23B knockdown inhibited NSCLC development by regulating the miR‐142‐3p/MAP4K3 axis, which might be associated with the inactivation of the MAPK signaling pathway.

Circular RNAs in Intervertebral Disc Degeneration: An Updated Review

Low back pain, a common medical condition, could result in severe disability and inflict huge economical and public health burden. Its pathogenesis is attributed to multiple etiological factors, including intervertebral disc degeneration (IDD). Emerging evidence suggests that circular RNAs (circRNAs), a major type of regulatory non-coding RNA, play critical roles in cellular processes that are pertinent to IDD development, including nucleus pulposus cell proliferation and apoptosis as well as extracellular matrix deposition. Increasing number of translational studies also indicated that circRNAs could serve as novel biomarkers for the diagnosis of IDD and/or predicting its clinical outcomes. Our review aims to discuss the recent progress in the functions and mechanisms of newly discovered IDD-related circRNAs.

Circ_0007385 regulates cell proliferation, apoptosis and stemness via targeting miR-493-3p/RAB22A axis in non-small cell lung cancer

BACKGROUND

Non-small cell lung cancer (NSCLC) is a common cancer in the United States. Previous studies have shown that circular RNAs (circRNAs) can affect NSCLC progression, but its regulatory mechanism is still indistinct. In this study, we unfold the roles of circular RNA_0007385 in NSCLC tissues and cells.

METHODS

Expression levels of circ_0007385, microRNA-493-3p (miR-493-3p) and Ras-related protein Rab-22A (RAB22A) were detected by quantitative real-time polymerase chain reaction (qRT-PCR) in NSCLC tissues and cells. Cell proliferation, apoptosis and stemness were examined by cell counting kit 8 (CCK8) assay, 5-ethynyl-2'-deoxyuridine (EdU) assay, flow cytometry analysis and sphere-formation assay. The interaction between miR-493-3p and circ_0007385 or RAB22A was forecasted by bioinformatic analysis and detected by dual-luciferase reporter assay, RNA immunoprecipitation (RIP) and RNA pulldown assays. In vivo experiments were implemented to verify the effect of circ_0007385 in vivo.

RESULTS

Expression of circ_0007385 and RAB22A increased, whereas miR-493-3p level was decreased in NSCLC tissues in contrast to that in normal tissues. For functional analysis, circ_0007385 deficiency inhibited cell proliferation and stemness, whereas it promoted cell apoptosis in NSCLC cells. Mechanically, circ_0007385 acted as a miR-493-3p sponge to modulate RAB22A expression. Moreover, circ_0007385 could regulate the development of NSCLC by sponging miR-493-3p to regulate the expression of RAB22A. In addition, circ_0007385 silence also attenuated tumor growth in vivo.

CONCLUSIONS

Circ_0007385 promoted NSCLC progression by sponging miR-493-3p to increase RAB22A expression, which also offered an underlying targeted therapy for NSCLC treatment.

Circ_0011385 knockdown inhibits cell proliferation, migration and invasion, whereas promotes cell apoptosis by regulating miR-330-3p/MYO6 axis in colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is a malignant tumor. Recent studies have showed circular RNA (circRNA) participates in the development of CRC. The study was designed to reveal the role of circ_0011385 in CRC progression and underneath mechanism.

METHODS

The expression circ_0011385, microRNA-330-3p (miR-330-3p) and myosin VI (MYO6) mRNA were determined by quantitative real-time polymerase chain reaction. Protein expression was detected by Western blot assay. Cell proliferation was investigated by 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide (MTT), cell colony formation and flow cytometry assays. Cell apoptosis was demonstrated by flow cytometry analysis. Cell migration and invasion were evaluated by wound-healing assay and transwell invasion assay, respectively. The binding sites between miR-330-3p and circ_0011385 or MYO6 were predicted by CircInteractome or starBase online databases, and identified by dual-luciferase reporter and RNA immunoprecipitation assays.

RESULTS

Circ_0011385 and MYO6 expression were dramatically upregulated, while miR-330-3p expression was downregulated in CRC tissues or cells compared with control groups. Circ_0011385 expression was associated with tumor size, tumor-node-metastasis stage (TNM) stage and lymph node metastasis of CRC patients. Circ_0011385 silencing or MYO6 absence repressed cell proliferation, migration and invasion, whereas induced cell apoptosis in CRC. Additionally, miR-330-3p inhibitor or MYO6 overexpression attenuated the repressive impacts of circ_0011385 silencing on CRC process. Circ_0011385 was associated with miR-330-3p, and miR-330-3p targeted MYO6. Circ_0011385 knockdown inactivated MEK1/2/ERK1/2 signaling pathway by miR-330-3p/MYO6 axis. Furthermore, circ_0011385 knockdown suppressed tumor growth in vivo.

CONCLUSION

Circ_0011385 regulated CRC process by miR-330-3p/MYO6 axis through MEK1/2/ERK1/2 signaling pathway, providing a novel therapeutic target for CRC.

Circular RNA hsa_circ_0000317 inhibits non-small cell lung cancer progression through regulating microRNA-494-3p/phosphatase and tensin homolog deleted on chromosome 10 axis

BACKGROUND

Circular RNA (circRNA), a group of non-coding RNA, is pivotal in the progression of various cancers, including Non-Small Cell Lung Cancer (NSCLC). Some circRNAs have been reported to be implicated in the progression of NSCLC, however, the function and molecular mechanism of hsa_circ_0000317 (circ_0000317) in NSCLC have not been fully understood.

METHODS

The significantly differentially expressed circRNA in NSCLC tissues, circ_0000317, was screened out by microarray. Circ_0000317, microRNA(miR)-494-3p and Phosphatase and Tensin Homolog Deleted on Chromosome 10 (PTEN) expressions in NSCLC tissues were respectively probed by quantitative real-time polymerase chain reaction and western blot assay. MTT and Transwell assays were adopted to examine the growth, migration, and invasion of NSCLC cells. Bioinformatics, luciferase reporter gene assay, RNA immunoprecipitation, and RNA pull-down assay were conducted to probe the relationships among circ_0000317, miR-494-3p, and PTEN.

RESULTS

Circ_0000317 expression level was reduced in NSCLC tissues and cell lines. Circ_0000317 expression in NSCLC patients was associated with TNM stage and lymphatic metastasis. Circ_0000317 overexpression restrained the proliferation, migration, and invasion of NSCLC cells, but co-transfection of miR-494-3p mimics partially reversed this effect. In addition, circ_0000317, was identified as a competitive endogenous RNA, which could sponge miR-494-3p to increase PTEN expression and activate PI3K/AKT pathway.

CONCLUSION

Circ_0000317, inhibits NSCLC progression via modulating miR-494-3p/PTEN/PI3K/AKT pathway.

Dysregulated expression and functions of microRNA-330 in cancers: A potential therapeutic target

As small non-coding RNAs, MicroRNAs (miRNAs) bind to the 3' untranslated region (3'-UTR) of mRNA targets to control gene transcription and translation. The gene of miR-330 has two miRNA products, including miR-330-3p and miR-330-5p, which exhibit anti-tumorigenesis and/or pro-tumorigenesis effects in many kinds of malignancies. In cancers, miR-330-3p and miR-330-5p aberrant expression can influence many malignancy-related processes such as cell proliferation, migration, invasion, apoptosis and epithelial-mesenchymal transition, as well as angiogenesis and responsiveness to treatment. In many cancer types (such as lung, prostate, gastric, breast, bladder, ovarian, colorectal, and pancreatic cancer, and osteosarcoma), miR-330-5p acts as an anti-tumor agent. These cancers have low levels of miR-330-5p that leads to the upregulation of the tumor promotor target genes leading to tumor progression. Here, overexpression of miR-330-5p using miRNA inducers can prevent tumor development. Dual roles of miR-330-5p have been also indicated in the thyroid, liver and cervical cancers. Moreover, miR-330-3p exhibits pro-tumorigenesis effects in lung cancer, pancreatic cancer, osteosarcoma, bladder cancer, and cervical cancer. Here, downregulation of miR-330-3p using miRNA inhibitors can prevent tumor development. Demonstrated in breast and liver cancers, miR-330-3p also has dual roles. Importantly, the activities of miR-330-3p and/or miR-330-5p are regulated by upstream regulators long non-coding RNAs (lncRNAs), including circular and linear lncRNAs. This review comprehensively explained miR-330-3p and miR-330-5p role in development of cancers, while highlighting their downstream target genes and upstream regulators as well as possible therapeutic strategies.

IRF4-activated TEX41 promotes the malignant behaviors of melanoma cells by targeting miR-103a-3p/C1QB axis

BACKGROUND

Malignant melanoma is an aggressive skin cancer and a tumor of melanocytic origin. Recent studies have suggested that long non-coding RNAs (lncRNAs) play crucial regulatory roles in multiple malignancies, including melanoma. Testis expressed 41 (TEX41) is a relatively new lncRNA whose mechanism in melanoma remains vague.

AIMS

This study aimed to explore the role and specific mechanism of TEX41 in melanoma.

METHODS

The expression of genes involved in this study was determined by qRT-PCR. Functional assays were conducted to analyze the role of relevant genes in melanoma cells. The interaction between TEX41 promoter and IRF4 as well as the relationship among TEX41, miR-103a-3p and C1QB was verified by mechanism assays.

RESULTS

IRF4 up-regulated TEX41 at the transcriptional level in melanoma cells. TEX41 knockdown hindered melanoma cell proliferation, migration and invasion while promoting cell apoptosis. TEX41 bound to miR-103a-3p and regulated C1QB. The suppressive impact of TEX41 depletion on melanoma cell malignant behaviors could be counteracted by miR-103a-3p inhibition or C1QB overexpression. Moreover, IRF4 could facilitate melanoma cell growth via up-regulating C1QB.

CONCLUSIONS

IRF4-activated TEX41 sequestered miR-103a-3p and modulated C1QB to promote melanoma cell malignant behaviors, for which TEX41 might be regarded as a potential therapeutic target for melanoma.