Circular RNA 100146 functions as an oncogene through direct binding to miR-361-3p and miR-615-5p in non-small cell lung cancer

Engineering of a palindrome-crosslinked DNA nanoaggregate for rapid detection of circular RNA and precise identification of lung cancer

Circular RNAs (circRNAs) are endogenous covalently closed non-coding RNAs with cell-/developmental-stage-/tissue-specific expression patterns, and they can act as the miRNA sponges and gene transcription regulatory factors to influence numerous biological processes. Herein, we develop a palindrome-crosslinked DNA nanoaggregate system to rapidly detect circRNA and precisely identify lung cancer. We utilize a self-assembled palindromic DNA nanosphere (DS) as the spatial-confinement scaffold to anchor hairpin probes (HP) for the formation of the hybrid assemblies (DSH). The presence of target circSATB2 can hybridize with the hairpin probe to expose the locked palindromic sequence, initiating the cross-linking of the palindromic ends to form a self-catenated structure through intermolecular hybridization. Then the hybridized palindromic ends serve as the self-primers to initiate extension reaction and eventually assemble into the net-like crosslinked DNA nanoaggregates, resulting in the recovery of Cy5 signals. Taking advantage of the excellent antidegradation capability and superior kinetic behavior of DSH nanostructure, high amplification efficiency of Klenow Fragment polymerase (KF)-mediated extension reaction, and signal enhancement induced by the DNA nanoaggregates, this nanosystem enables mix-and-read detection of circSATB2 within 30 min under isothermal conditions (37 °C) with a limit detection of 77.56 fM. Moreover, it is capable of measuring intracellular circSATB2 with single-cell sensitivity, exploring its biological functions, and precisely identifying different stages (I/II/III) and subtypes (IA1/IA2/IA3/IB) of lung cancers, holding great potential in early screening of lung cancers.

Human and pathogen-encoded circular RNAs in viral infections: insights into functions and therapeutic opportunities

Circular RNAs (circRNAs) are emerging as important regulatory molecules in both host and viral systems, acting as microRNA sponges, protein decoys or scaffolds, and templates for protein translation. Host-derived circRNAs are increasingly recognized for their roles in immune responses, while virus-encoded circRNAs, especially those from DNA viruses, have been shown to modulate host cellular machinery to favor viral replication and immune evasion. Recently, RNA virus-encoded circRNAs were also discovered, but evidence suggests that they might be generated using a different mechanism compared to the circRNAs produced from the host and DNA viruses. This review highlights recent advances in our understanding of both host and virus-derived circRNAs, with a focus on their biological roles and contributions to pathogenesis. Furthermore, we discuss the potential of circRNAs as biomarkers and their application as therapeutic targets or scaffolds for RNA-based therapies. Understanding the roles of circRNAs in host-virus interactions offers novel insights into RNA biology and opens new avenues for therapeutic strategies against viral diseases and associated cancers.

Non-coding RNAs in thoracic disease: Barrett's esophagus and esophageal adenocarcinoma

Esophageal adenocarcinoma (EAC) is a highly aggressive malignancy with increasing incidence and poor survival rates, primarily due to late-stage diagnosis. This cancer often develops from Barrett's Esophagus (BE), a precancerous condition linked to chronic gastroesophageal reflux disease (GERD). The transition from BE to EAC is a complex multistep process involving numerous genetic, epigenetic, and molecular changes that lead to the malignant transformation of the esophageal epithelium. Despite advancements in understanding the molecular mechanisms underlying EAC, early detection and effective treatment options remain limited, highlighting an urgent need for innovative diagnostic and therapeutic strategies. Recent research has focused on non-coding RNAs (ncRNAs), which play crucial roles in regulating gene expression and cellular processes relevant to cancer progression. Various types of ncRNAs, including microRNAs, long non-coding RNAs, and circular RNAs, have been implicated in the development of BE and EAC by modulating key signaling pathways such as Wnt/β-catenin and NF-κB. Additionally, ncRNAs are stable in biological fluids, presenting opportunities for their use as non-invasive biomarkers for early detection and monitoring of EAC. This review aims to elucidate the involvement of ncRNAs in the progression from BE to EAC, their potential as therapeutic targets, and their emerging roles in intercellular communication. We will also discuss the challenges in translating ncRNA research into clinical applications, emphasizing their promise in revolutionizing early detection and treatment strategies for EAC.

CircMFN2/miR-361-3p/ELK1 feedback loop promotes glutaminolysis and the progression of hepatocellular carcinoma

Current evidence indicates that circRNAs are involved in the development of multiple malignancies including hepatocellular carcinoma (HCC). However, the specific functions of circRNAs in HCC metabolism and progression and their underlying regulatory mechanisms remain unclear. We have identified a novel circRNA circMFN2, by bioinformatics analysis of circRNA microarray data from the GEO database. The levels of circMFN2 were assessed in HCC cell lines and tissues, and its clinical relevance was assessed. The effect of circMFN2 on HCC cells was evaluated in vitro and in vivo. The effect of ELK1 on glutaminolysis and HCC progression was also explored. Patients with HCC and high circMFN2 expression exhibited worse survival outcomes. Functionally, downregulation of circMFN2 repressed the proliferation, invasion, and migration of HCC cells in vitro, whereas ectopic expression of circMFN2 had the opposite effects. The effects of tumor enhancement by circMFN2 on HCC were confirmed by in vivo experiments. Mechanistically, circMFN2 acted as a sponge for miR-361-3p, leading to the upregulation of its target ELK1, whereas ELK1 was enriched in the MFN2 promoter to enhance the transcription and expression of MFN2, indirectly leading to the upregulation of circMFN2. Additionally, we found that circMFN2 promotes glutaminolysis in HCC by increasing ELK1 phosphorylation. We concluded that circMFN2 facilitates HCC progression via a circMFN2/miR-361-3p/ELK1 feedback loop, which promotes glutaminolysis mediated by the upregulation of phosphorylated ELK1. Therefore, circMFN2 not only serves as a potential prognostic indicator, but it could also serve as a therapeutic target for HCC. Further studies are warranted.

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.

Metastasis and chemoresistance in breast cancer: Crucial function of ZEB1/2 proteins

Breast cancer remains one of the leading causes of mortality worldwide. While advancements in chemotherapy, immunotherapy, radiotherapy, and targeted therapies have significantly improved breast cancer treatment, many patients are diagnosed at advanced stages, where tumor cells exhibit aggressive behavior and therapy resistance. Understanding the mechanisms driving breast cancer progression is therefore critical. Metastasis is a major factor that drastically reduces patient prognosis and survival, accounting for most breast cancer-related deaths. ZEB proteins have emerged as key regulators of cancer metastasis. Beyond their role in metastasis, ZEB proteins also influence drug resistance. This review focuses on the role of ZEB1 and ZEB2 in regulating breast cancer metastasis. These proteins interact with components of the tumor microenvironment (TME) to drive cancer progression and metastasis. Additionally, ZEB proteins regulate angiogenesis through interactions with VEGF. Targeting ZEB proteins offers potential therapeutic benefits, particularly for aggressive breast cancer subtypes such as triple-negative breast cancer (TNBC), which often show poor therapeutic response. ZEB proteins also influence the sensitivity of breast cancer cells to chemotherapy, making them promising targets for enhancing treatment efficacy. Given their upregulation in breast cancer, ZEB proteins can serve as valuable diagnostic and prognostic markers.

Circular RNA circHSPA8 Aggravates Metastasis by Acting as a Competitive Inhibitor of miR-195-5p to Upregulate WNT3A Expression in Breast Cancer

Circular RNA (circRNA) plays a vital role in the tumorigenicity and progression of cancer by regulating various biological behaviours. It acts as a microRNA sponge, disrupting transcription and the abnormal expression of oncogenes. Hsa_circ_0024715, a circRNA generated from cyclization at specific sites of the HSPA8 gene, has been found to be highly expressed in breast cancer (BC) tissue based on non-coding RNA high-throughput sequencing. However, its functions remain poorly understood. In this study, we performed qPCR to evaluate the expression of circHSPA8 in BC tissues. Survival analysis in a prospective cohort revealed that high expression of circHSPA8 is associated with poor prognosis and lymphoid node metastasis. Overexpression of circHSPA8 in MCF-7 cells significantly enhanced their proliferative and invasive abilities, whereas knockdown of circHSPA8 in MDA-MB-231 cells significantly reduced their proliferative and invasive abilities. We found that circHSPA8 can promote epithelial-mesenchymal transition (EMT) in BC cells, primarily by upregulating the expression of WNT3A. This process depends on the sponging and inhibition of miR-195-5p, which suppresses the proliferation, invasion, and metastasis of BC cells. In vivo experiments further confirmed that circHSPA8 can promote the intravasation and extravasation of BC cells as well as the formation of metastatic lesions in the lungs. In summary, these data demonstrate that circHSPA8 promotes EMT by acting as a competitive inhibitor of miR-195-5p to upregulate the expression of WNT3A in BC, suggesting that dysregulation of circRNA in BC might be a pathological factor and potential therapeutic target.

A Novel 167-Amino Acid Protein Encoded by CircPCSK6 Inhibits Intrahepatic Cholangiocarcinoma Progression via IKBα Ubiquitination

Intrahepatic cholangiocarcinoma (ICC), a formidable challenge in oncology, demands innovative biomarkers and therapeutic targets. This research highlights the importance of the circular RNA (circRNA) circPCSK6 and its peptide derivative circPCSK6-167aa in ICC. CircPCSK6 is significantly downregulated in both ICC patients and mouse primary ICC models, and its lower expression is linked to adverse prognosis, highlighting its pivotal role in ICC pathogenesis. Functionally, this study elucidates the regulatory effect of circPCSK6-167aa on IκBα ubiquitination within the NF-κB pathway, which is mediated by its competitive binding to the E3 ligase RBBP6. This complex interaction leads to reduced activation of the NF-κB pathway, thereby curbing tumor cell proliferation, migration, invasion, stemness, and hepatic-lung metastasis in vivo. This groundbreaking discovery expands the understanding of circRNA-driven tumorigenesis through atypical signaling pathways. Additionally, this investigation identified EIF4A3 as a detrimental regulator of circPCSK6, exacerbating ICC malignancy. Importantly, by leveraging patient-derived xenograft (PDX), organoids, and organoid-derived PDX models, higher levels of circPCSK6-167aa enhance sensitivity to gemcitabine, indicating its potential to improve the effectiveness of chemotherapy. These insights emphasize the therapeutic promise of targeting circPCSK6-167aa, offering vital biological insights and clinical directions for developing cutting-edge therapeutic approaches, thus revealing innovative strategies and targets for future treatments.

Top 100 most-cited articles on apoptosis of non-small cell lung cancer over the past two decades: a bibliometrics analysis

Background

Recently there has been an increasing number of studies have explored apoptosis mechanisms in lung cancer (LC). However, no researchers have conducted a bibliometric analysis of the most cited articles in this field.

Objective

To examine the top 100 most influential and cited publications on apoptosis in non-small cell lung cancer (NSCLC) from 2004 to 2023, summarizing research trends and key focus areas.

Methods

This study utilized the Web of Science Core Database (WOSCC) to research NSCLC apoptosis from 2004 to 2023, using keyword selection and manual screening for article searches. Bibliometrix package of R software 4.3.1 was used to generate distribution statistics for the top ten institutions, journals and authors. Citespace6.2. R6 was used to create the visualization maps for keyword co-occurrence and clustering. VOSviewer1.6.19 was used to conduct cluster analysis of publishing countries (regions), with data exported to SCImago Graphica for geographic visualization and cooperation analysis. VOSviewer1.6.19 was used to produced co-citation maps of institutions, journals, authors, and references.

Results

From 2004 to 2023, 13316 articles were retrieved, and the top 100 most cited were chosen. These were authored by 934 individuals from 269 institutions across 18 countries and appeared in 45 journals. Citations ranged from 150 to 1,389, with a median of 209.5. The most influential articles appeared in 2005 and 2007 (n=13). The leading countries (regions), institutions, journals and authors were identified as the United States (n=60), Harvard University (n=64), CANCER RESEARCH (n=15), SUN M and YANG JS (n=6). The top five keywords were "expression", "activation", "apoptosis", "pathway" and "gefitinib". This study indicates that enhancing apoptosis through circular RNA regulation and targeting the Nrf2 signaling pathway could become a key research focus in recent years.

Conclusion

Apoptosis has been the subject of extensive research over many years, particularly in relation to its role in the pathogenesis, diagnosis, and treatment of NSCLC. This study aims to identify highly influential articles and forecast emerging research trends, thereby offering insights into novel therapeutic targets and strategies to overcome drug resistance. The findings are intended to serve as a valuable reference for scholars engaged in this field of study.

The role of circRNA in breast cancer drug resistance

Among women with cancer, breast cancer has surpassed lung cancer to become the most prevalent type of cancer globally. High-throughput sequencing of breast cancer tissues from many patients has revealed significant variations in circRNA expression across different types of breast cancer. Chemotherapy is currently a very important method for treating breast cancer; however, as the number of chemotherapy sessions increases and considering factors such as the patient's immune response, drug resistance has become a challenging issue in treating breast cancer. It is well known that drug resistance is associated with multiple factors, and different resistance mechanisms involve different roles of circRNA. This review consolidates literature from the past 5 years and addresses the shortcomings in the broad description of circRNA's role in breast cancer drug resistance. It categorizes and describes the drug resistance and its mechanisms in different types of breast cancer, as well as the roles of circRNA and signaling pathways in drug resistance.

Hsa_circ_0023179 modulated the processes of proliferation, apoptosis, and EMT in non-small cell lung cancer cells via the miR-615-5p/CDH3 axis

Circular RNA (circRNA) has been widely studied as a competitive endogenous RNA targeting microRNA (miRNA)/messenger RNA to regulate cancer progression. However, the regulatory mechanism of circ_0023179 in non-small cell lung cancer (NSCLC) remains unclear. The expression levels of circ_0023179, miR-615-5p and Cadherin 3 (CDH3) in NSCLC were detected using quantitative real-time polymerase chain reaction. The stability of circ_0023179 was verified using ribonuclease R enzyme, actinomycin D and agarose gel electrophoresis. Colony formation and thymidine analog 5-ethynyl-2'-deoxyuridine assays were performed to examine proliferation changes in NSCLC cells. Western blot was used to assess the levels of CDH3 and epithelial-mesenchymal transition (EMT)-related marker proteins to evaluate EMT. Dual-luciferase reporter, RNA immunoprecipitation (RIP), and RNA pull-down assays were performed to explore the potential mechanisms of circ_0023179 in regulating NSCLC progression. Finally, the effects of circ_0023179 on NSCLC tumour growth in vivo were explored using a nude mouse subcutaneous tumour model. The results showed that the expression of circ_0023179 was remarkably higher in NSCLC tissues and cells, and it had a significant effect on NSCLC cell proliferation. Additionally, the knockdown of circ_0023179 significantly inhibited tumour growth in NSCLC mice. Mechanistically, circ_0023179 alleviated its inhibition of downstream CDH3 through the sponge-like adsorption of miR-615-5p. The downregulation of miR-615-5p and the upregulation of CDH3 mitigated the inhibitory effect of silencing circ_0023179 on NSCLC cell proliferation. In conclusion, silencing circ_0023179 inhibited NSCLC cell proliferation by targeting the miR-615-5p/CDH3 axis involved in NSCLC progression.

Circular RNA LMBR1 inhibits bladder cancer progression by enhancing expression of the protein ALDH1A3

Background

Circular RNAs (circRNAs) have been identified as playing an integral role in the development of bladder cancer (BC). However, the mechanism by which circRNAs operate in the chemical carcinogenesis of BC remains unclear.

Methods

To explore this mechanism, we used RNA high-throughput sequencing to identify differentially expressed circRNA in bladder epithelial cells and chemically induced malignant transformed BC cells. Subsequently, in vitro experiments were conducted to investigate the biological function and molecular mechanism of circLMBR1 in BC. Finally, animal experiments were conducted to examine the clinical relevance of circLMBR1 in vivo.

Results

Our profiling of circular RNA expression during cellular malignant transformation induced by chemical carcinogens identified a subset of circRNAs associated with cell transformation. We verified that the expression of circLMBR1 in bladder epithelial malignant transformed cells was decreased compared with control cells, as well as in BC tissues and bladder cell lines. Furthermore, circLMBR1 was seen to inhibit the proliferation, invasion, and migration of BC cells both in vitro and in vivo. Mechanistically, circLMBR1 was found to exert its antitumor effect by binding to the protein ALDH1A3.

Conclusions

Our findings have revealed that circLMBR1 inhibits the progression of BC cells by binding to ALDH1A3 and upregulating its expression. As such, circLMBR1 serves as a promising predictor of BC and may provide a novel therapeutic target for the treatment of BC.

The crosstalk between alternative splicing and circular RNA in cancer: pathogenic insights and therapeutic implications

RNA splicing is a fundamental step of gene expression. While constitutive splicing removes introns and joins exons unbiasedly, alternative splicing (AS) selectively determines the assembly of exons and introns to generate RNA variants corresponding to the same transcript. The biogenesis of circular RNAs (circRNAs) is inextricably associated with AS. Back-splicing, the biogenic process of circRNA, is a special form of AS. In cancer, both AS and circRNA deviate from the original track. In the present review, we delve into the intricate interplay between AS and circRNAs in the context of cancer. The relationship between AS and circRNAs is intricate, where AS modulates the biogenesis of circRNAs and circRNAs in return regulate AS events. Beyond that, epigenetic and posttranscriptional modifications concurrently regulate AS and circRNAs. On the basis of this modality, we summarize current knowledge on how splicing factors and other RNA binding proteins regulate circRNA biogenesis, and how circRNAs interact with splicing factors to influence AS events. Specifically, the feedback loop regulation between circRNAs and AS events contributes greatly to oncogenesis and cancer progression. In summary, resolving the crosstalk between AS and circRNA will not only provide better insight into cancer biology but also provoke novel strategies to combat cancer.

Differences in alternative splicing and their potential underlying factors between animals and plants

BACKGROUND

Alternative splicing (AS), a posttranscriptional process, contributes to the complexity of transcripts from a limited number of genes in a genome, and AS is considered a great source of genetic and phenotypic diversity in eukaryotes. In animals, AS is tightly regulated during the processes of cell growth and differentiation, and its dysregulation is involved in many diseases, including cancers. Likewise, in plants, AS occurs in all stages of plant growth and development, and it seems to play important roles in the rapid reprogramming of genes in response to environmental stressors. To date, the prevalence and functional roles of AS have been extensively reviewed in animals and plants. However, AS differences between animals and plants, especially their underlying molecular mechanisms and impact factors, are anecdotal and rarely reviewed.

AIM OF REVIEW

This review aims to broaden our understanding of AS roles in a variety of biological processes and provide insights into the underlying mechanisms and impact factors likely leading to AS differences between animals and plants.

KEY SCIENTIFIC CONCEPTS OF REVIEW

We briefly summarize the roles of AS regulation in physiological and biochemical activities in animals and plants. Then, we underline the differences in the process of AS between plants and animals and especially analyze the potential impact factors, such as gene exon/intron architecture, 5'/3' untranslated regions (UTRs), spliceosome components, chromatin dynamics and transcription speeds, splicing factors [serine/arginine-rich (SR) proteins and heterogeneous nuclear ribonucleoproteins (hnRNPs)], noncoding RNAs, and environmental stimuli, which might lead to the differences. Moreover, we compare the nonsense-mediated mRNA decay (NMD)-mediated turnover of the transcripts with a premature termination codon (PTC) in animals and plants. Finally, we summarize the current AS knowledge published in animals versus plants and discuss the potential development of disease therapies and superior crops in the future.

Circ_0025373 inhibits carbon black nanoparticles-induced malignant transformation of human bronchial epithelial cells by affecting DNA damage through binding to MSH2

Carbon black nanoparticles (CBNPs) have been demonstrated to induce DNA damage in epithelial cells. However, the potential of the damage to initiate carcinogenesis and the underlying mechanism remain poorly understood. Therefore, we constructed an in vitro model of malignant transformation of human bronchial epithelial cells (16HBE-T) by treating 40 μg/mL CBNPs for 120 passages. We observed tumor-like transformation and sustained DNA damage. Using transcriptome sequencing and RIP-seq, we identified the overexpression of the critical DNA mismatch repair genes MutS homolog 2 (MSH2) and its related circular RNA, circ_0025373, in the 16HBE-T cells. Mechanistically, circ_0025373 was found to inhibit DNA damage by binding to MSH2, thereby modifying its expression and influencing its nuclear and cytoplasmic distribution, which lead to inhibition of CBNP-induced malignant transformation of human bronchial epithelial cells. Our findings provide novel evidence on the carcinogenicity of CBNPs, and offer biological insights into the potential epigenetic regulation and potential therapeutic targets for lung carcinogenesis.

Circ-PITX1 promotes non-small-cell lung cancer progression through regulating ETS1 expression via miR-615-5p

BACKGROUND

Circular RNAs (circRNAs), produced by reverse splicing, act as important players in human cancers. We aimed to assess the biological functions of circRNA pituitary homeobox 1 (circ-PITX1) in non-small-cell lung cancer (NSCLC).

METHODS

qRT-PCR was employed to determine RNA expression. Biological behaviors of NSCLC cells were assessed by CCK-8, colony formation, EdU assay, flow cytometry, wound healing, and transwell assays. Glutamine catabolism was examined via the measurement of glutamine consumption, α-ketoglutarate levels, as well as ATP levels. Protein levels were detected by western blot assays. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were performed to reveal the mechanism responsible for circ-PITX1 regulating NSCLC cell malignancy. The murine xenograft model was established to investigate circ-PITX1's effect on tumor formation.

RESULTS

Circ-PITX1 was overexpressed in NSCLC tissue samples and cells. Its low expression repressed NSCLC cell proliferation and motility. Moreover, our data revealed its downregulation inhibited glutamine catabolism and tumor formation and promoted cell apoptosis. In addition, circ-PITX1 bound to miR-615-5p, and its inhibitory effect on tumor cellular behaviors could be reversed after decreasing miR-615-5p expression. The miRNA targeted E26 transformation specific-1 (ETS1), whose upregulation abolished miR-615-5p overexpression-induced effects in NSCLC cells. Furthermore, circ-PITX1 positively modulated ETS1 production through interaction with miR-615-5p.

CONCLUSION

Circ-PITX1 facilitated NSCLC progression via modulating miR-615-5p/ETS1 pathway.

circ-ATAD1 as Competing Endogenous RNA for miR-191-5p Forces Non-small Cell Lung Cancer Progression

The association of circular RNAs (circRNAs) with non-small cell lung cancer (NSCLC) has been recognized extensively. In view of this, our study particularly surveyed the underlying mechanism of circ-ATAD1 in the disease. First, an analysis of the clinical expression of circ-ATPase family AAA domain containing 1 (ATAD1) was performed, followed by further evaluation of the relationship between circ-ATAD1 expression and prognosis. Then, A549 cells were treated with single transfection or combined transfection with the plasmid vectors that interfere with circ-ATAD1 or miR-191-5p. circ-ATAD1 and miR-191-5p levels were detected by reverse transcription quantitative polymerase chain reaction to verify the transfection success. Then, cell proliferation was checked by cell count kit-8 and clonal formation test. Cell apoptosis was analyzed by flow cytometry. Cell migration and invasion were examined by wound healing assay and Transwell. Finally, the targeting of miR-191-5p to circ-ATAD1 or Forkhead Box K1 (FOXK1) was verified by bioinformation website starBase analysis and dual-luciferase reporter assay. circ-ATAD1 was expressed abundantly in tumor tissues of NSCLC patients and had a predictive value in poor prognosis. circ-ATAD1 underexpression or miR-191-5p overexpression could obstruct A549 cells to behave aggressively, while circ-ATAD1 upregulation or miR-191-5p depletion resulted in the promotion of aggressiveness of A549 cells. Interestingly, circ-ATAD1 could decoy miR-191-5p. miR-191-5p negatively regulated FOXK1 expression, and downregulating miR-191-5p or upregulating FOXK1 rescued circ-ATAD1 downregulation-mediated influences on NSCLC cells. circ-ATAD1 accelerates NSCLC progression by absorbing miR-191-5p to upregulate FOXK1 expression.

Hypoxia-enhanced YAP1-EIF4A3 interaction drives circ_0007386 circularization by competing with CRIM1 pre-mRNA linear splicing and promotes non-small cell lung cancer progression

BACKGROUND

The progression of non-small cell lung cancer (NSCLC) is significantly influenced by circular RNAs (circRNAs), especially in tumor hypoxia microenvironment. However, the precise functions and underlying mechanisms of dysregulated circRNAs in NSCLC remain largely unexplored.

METHODS

Differentially expressed circRNAs in NSCLC tissues were identified through high-throughput RNA sequencing. The characteristics of circ_0007386 were rigorously confirmed via Sanger sequencing, RNase R treatment and actinomycin D treatment. The effects of circ_0007386 on proliferation and apoptosis were investigated using CCK8, cloning formation assays, TUNEL staining, and flow cytometry assays in vitro. In vivo, xenograft tumor models were used to evaluate its impact on proliferation. Mechanistically, the regulatory relationships of circ_0007386, miR-383-5p and CIRBP were examined through dual luciferase reporter assays and rescue experiments. Additionally, we detected the binding of EIF4A3 to CRIM1 pre-mRNA by RNA immunoprecipitation and the interaction between YAP1 and EIF4A3 under hypoxic conditions by co-immunoprecipitation.

RESULTS

Our investigation revealed a novel circRNA, designated as circ_0007386, that was upregulated in NSCLC tissues and cell lines. Circ_0007386 modulated proliferation and apoptosis in NSCLC both in vitro and in vivo. Functionally, circ_0007386 acted as a sponge for miR-383-5p, targeting CIRBP, which influenced NSCLC cell proliferation and apoptosis via the PI3K/AKT signaling pathway. Furthermore, under hypoxic conditions, the interaction between YAP1 and EIF4A3 was enhanced, leading to the displacement of EIF4A4 from binding to CRIM1 pre-mRNA. This facilitated the back-splicing of CRIM1 pre-mRNA, increasing the formation of circ_0007386. The circ_0007386/miR-383-5p/CIRBP axis was significantly associated with the clinical features and prognosis of NSCLC patients.

CONCLUSIONS

Circ_0007386, regulated by YAP1-EIF4A3 interaction under hypoxia conditions, plays an oncogenic role in NSCLC progression via the miR-383-5p/CIRBP axis.

Engineering circular RNA for molecular and metabolic reprogramming

The role of messenger RNA (mRNA) in biological systems is extremely versatile. However, it's extremely short half-life poses a fundamental restriction on its application. Moreover, the translation efficiency of mRNA is also limited. On the contrary, circular RNAs, also known as circRNAs, are a common and stable form of RNA found in eukaryotic cells. These molecules are synthesized via back-splicing. Both synthetic circRNAs and certain endogenous circRNAs have the potential to encode proteins, hence suggesting the potential of circRNA as a gene expression machinery. Herein, we aim to summarize all engineering aspects that allow exogenous circular RNA (circRNA) to prolong the time that proteins are expressed from full-length RNA signals. This review presents a systematic engineering approach that have been devised to efficiently assemble circRNAs and evaluate several aspects that have an impact on protein production derived from. We have also reviewed how optimization of the key components of circRNAs, including the topology of vector, 5' and 3' untranslated sections, entrance site of the internal ribosome, and engineered aptamers could be efficiently impacting the translation machinery for molecular and metabolic reprogramming. Collectively, molecular and metabolic reprogramming present a novel way of regulating distinctive cellular features, for instance growth traits to neoplastic cells, and offer new possibilities for therapeutic inventions.

circSORBS1 inhibits lung cancer progression by sponging miR-6779-5p and directly binding RUFY3 mRNA

Lung cancer is the primary cause of cancer-related death worldwide, and its global incidence and mortality rates remain high. The differential expression of circular RNAs (circRNAs) can affect the development of cancer, but the mechanisms by which circRNAs regulate lung cancer progression remain unclear. In this study, we identified circSORBS1, a circRNA that has not been previously described in lung cancer and is significantly underexpressed in lung cancer tissues, blood and cell lines, and the low expression of circSORBS1 correlated with tumour grade and prognosis. In vitro and in vivo functional experiments revealed that circSORBS1 overexpression inhibited cell proliferation and migration while enhancing apoptosis. Mechanistically, circSORBS1 acts as a sponge for miR-6779-5p, indirectly inhibiting RUFY3 mRNA degradation. Simultaneously, it binds to RUFY3 mRNA to enhance its stability. This dual regulatory mechanism leads to an increase in RUFY3 protein levels, which ultimately activates the YWHAE/BAD/BCL2 apoptotic signalling pathway and suppresses lung cancer progression. Our findings not only increase the knowledge about the regulatory pattern of circRNA expression but also provide new insights into the mechanisms by which circRNAs regulate lung cancer development.

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.

The role of circular RNAs in regulating resistance to cancer immunotherapy: mechanisms and implications

Cancer immunotherapy has rapidly transformed cancer treatment, yet resistance remains a significant hurdle, limiting its efficacy in many patients. Circular RNAs (circRNAs), a novel class of non-coding RNAs, have emerged as pivotal regulators of gene expression and cellular processes. Increasing evidence indicates their involvement in modulating resistance to cancer immunotherapy. Notably, certain circRNAs function as miRNA sponges or interact with proteins, influencing the expression of immune-related genes, including crucial immune checkpoint molecules. This, in turn, shapes the tumor microenvironment and significantly impacts the response to immunotherapy. In this comprehensive review, we explore the evolving role of circRNAs in orchestrating resistance to cancer immunotherapy, with a specific focus on their mechanisms in influencing immune checkpoint gene expression. Additionally, we underscore the potential of circRNAs as promising therapeutic targets to augment the effectiveness of cancer immunotherapy. Understanding the role of circRNAs in cancer immunotherapy resistance could contribute to the development of new therapeutic strategies to overcome resistance and improve patient outcomes.

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.

Circ0087385 promotes DNA damage in benzo(a)pyrene-induced lung cancer development by upregulating CYP1A1

Increasing environmental genotoxic chemicals have been shown to induce epigenetic alterations. However, the interaction between genetics and epigenetics in chemical carcinogenesis is still not fully understood. Here, we constructed an in vitro human lung carcinogenesis model (16HBE-T) by treating human bronchial epithelial cells with a typical significant carcinogen benzo(a)pyrene (BaP). We identified a novel circular RNA, circ0087385, which was overexpressed in 16HBE-T and human lung cancer cell lines, as well as in lung cancer tissues and serum exosomes from lung cancer patients. The upregulated circ0087385 after exposure to BaP promoted DNA damage in the early stage of chemical carcinogenesis and affected the cell cycle, proliferation, and apoptosis of the malignantly transformed cells. Overexpression of circ0087385 enhanced the expression of cytochrome P450 1A1 (CYP1A1), which is crucial for metabolically activating BaP. Interfering with circ0087385 or CYP1A1 reduced the levels of ultimate carcinogen benzo(a)pyrene diol epoxide (BPDE) and BPDE-DNA adducts. Interfering with CYP1A1 partially reversed the DNA damage induced by high expression of circ0087385, as well as decreased the level of BPDE and BPDE-DNA adducts. These findings provide novel insights into the interaction between epigenetics and genetics in chemical carcinogenesis which are crucial for understanding the epigenetic and genetic toxicity of chemicals.

Biological role and regulation of circular RNA as an emerging biomarker and potential therapeutic target for cancer

Circular RNAs (circRNAs) are a unique family of endogenous RNAs devoid of 3' poly-A tails and 5' end caps. These single-stranded circRNAs, found in the cytoplasm, are synthesized via back-splicing mechanisms, merging introns, exons, or both, resulting in covalently closed circular loops. They are profusely expressed across the eukaryotic transcriptome and offer heightened stability against exonuclease RNase R compared to linear RNA counterparts. This review endeavors to provide a comprehensive overview of circRNAs' characteristics, biogenesis, and mechanisms of action. Furthermore, aimed to shed light on the potential of circRNAs as significant biomarkers in various cancer types. It has been performed an exhaustive literature review, drawing on recent studies and findings related to circRNA characteristics, synthesis, function, evaluation techniques, and their associations with oncogenesis. CircRNAs are intricately associated with tumor progression and development. Their multifaceted roles encompass gene regulation through the sponging of proteins and microRNAs, controlling transcription and splicing, interacting with RNA binding proteins (RBPs), and facilitating gene translation. Due to these varied roles, circRNAs have become a focal point in tumor pathology investigations, given their promising potential as both biomarkers and therapeutic agents. CircRNAs, due to their unique biogenesis and multifunctionality, hold immense promise in the realm of oncology. Their stability, widespread expression, and intricate involvement in gene regulation underscore their prospective utility as reliable biomarkers and therapeutic targets in cancer. As our understanding of circRNAs deepens, advanced techniques for their detection, evaluation, and manipulation will likely emerge. These advancements might catalyze the translation of circRNA-based diagnostics and therapeutics into clinical practice, potentially revolutionizing cancer care and prognosis.

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.

KMT2A is targeted by miR-361-3p and modulates leukemia cell's abilities to proliferate, migrate and invade

OBJECTIVE

The lives and safety of humans are significantly threatened by acute myeloid leukemia (AML), which is proven to be the most prevalent acute leukemia. This work is therefore intended to investigate and analyze the expressions of miR-361-3p and Histone Lysine Methyltransferase 2A (KMT2A) in tissues and cell lines of AML and identify an advanced and novel target for the therapy of AML.

METHODS

The qRT-PCR and western blot assays were conducted to find expressions of miR-361-3p/KMT2A in AML PB and cell lines. After then, tests using CCK-8 and EdU were run to see how KMT2A affected the growth of AML cells. Transwell migration and invasion assay was conducted to evaluate KMT2A's contribution to the migration and invasion of AML cells. ENCORI and miRWalk predicted the association between KMT2A and miR-361-3p, and the dual-luciferase reporter experiment verified it. Furthermore, rescue studies were used to ascertain how KMT2A affected the miR-361-3p-regulated AML cells' abilities to proliferate, migrate, and invade.

RESULTS

miR-361-3p was poorly expressed while KMT2A was abundantly expressed. Additionally, KMT2A downregulation prevented AML cells from proliferating. PCNA and Ki-67 protein levels fell when KMT2A was silent. Furthermore, AML cells' motility, invasion, and metastasis were inhibited by low KMT2A expression. KMT2A was also identified as a direct target of miR-361-3p and negatively correlated with miR-361-3p. Finally, the over-expression of KMT2A partially reversed the inhibitory effects of up-regulation of miR-361-3p.

CONCLUSION

A potential therapeutic candidate target for the treatment of AML may be miR-361-3p/KMT2A.

CircWHSC1 serves as a prognostic biomarker and promotes malignant progression of non-small-cell lung cancer via miR-590-5p/SOX5 axis

Dysregulated circWHSC1 has been shown to play potential roles in diverse cancer types, including ovarian cancer, endometrial cancer and hepatocellular carcinoma (HCC). The objective of this study was to investigate its expression, underlying role and regulatory mechanism in non-small-cell lung cancer (NSCLC). The expression of circWHSC1 was determined by real-time PCR. After knockdown of circWHSC1 expression in NSCLC cells, the proliferation, migration, and invasion were detected using CCK-8, colony formation, and Transwell assays, and the effects of circWHSC1 on NSCLC tumorigenesis in vivo was also investigated. With the help of luciferase reporter and pull-down assays, we further explored the downstream mechanism of circWHSC1 in NSCLC cells. CircWHSC1 was highly expressed in NSCLC tissues and cell lines. The inhibition of circWHSC1 suppressed the malignant properties of NSCLC cells, as evidenced by the reduction of proliferation, migration and invasion. CircWHSC1 sponged miR-590-5p and functioned as an oncogene in NSCLC by increasing sex determining region Y-boxprotein 5 (SOX5) expression. CircWHSC1 may contribute to the oncogenicity of NSCLC via the regulation of miR-590-5p/SOX5 axis, which might be a novel therapeutic target in NSCLC.

Research trends and hotspots of exosomes in respiratory diseases

Currently, theoretical studies on exosomes in respiratory diseases have received much attention from many scholars and have made remarkable progress, which has inestimable value and potential in future clinical and scientific research. Unfortunately, no scholar has yet addressed this field's bibliometric analysis and summary. We aim to comprehensively and profoundly study and explore the present situation and highlights of exosome research at the stage of respiratory diseases and to provide meaningful insights for the future development of this field. The WOSCC literature was gathered for the study using bibliometrics, and the data were collected and analyzed using CiteSpace, VOSviewer, Microsoft Excel, and Endnote software. The publication language is "English," and the search strategy is TS = (exosome OR exosomes OR exosomal) AND TS = (respiratory OR lung). The search time is from the beginning of the WOS construction, and the deadline is July 11, 2022, at 22:00 hours. The literature types selected were dissertation, review paper, and online published paper. The analysis includes 2456 publications in 738 journals from 76 countries, 2716 institutions, and 14,568 authors. The field's annual publications have been rising, especially in recent years. China and the US lead research, and prominent universities, including Harvard Medical School, Shanghai Jiao Tong University, and Fudan University, are essential research institutes. Takahiro Ochiya, whose research focuses on exosomes and lung cancer, and Clotilde Théry, a pioneering exosome researcher, are the most cited authors in this field. The key terms include lung cancer, non-small cell lung cancer, mesenchymal stem cells, intercellular communication, exosomal miRNAs, and oncology. Cell biology, biochemistry & biotechnology, and oncology are related fields. The final summary of research hotspots is exosomes and lung cancer, mesenchymal stem cell-derived exosomes and lung inflammation, and miRNAs in exosomes as biomarkers for respiratory illnesses. The present research situation and relevant hotspots of the area were analyzed through bibliometric studies on exosomes in respiratory diseases. The research development in this field has a considerable upside, and the exosome's function in diagnosing, treating, monitoring, and prognosis of respiratory illnesses cannot be taken lightly. Moreover, we believe the research results will bring the gospel to many patients with clinical respiratory diseases shortly.

CircUCP2 promotes the tumor progression of non-small cell lung cancer through the miR-149/UCP2 pathway

Non-small cell lung cancer (NSCLC) is a highly lethal cancer, and better treatments are urgently needed. Many studies have implicated circular RNAs (circRNAs) in the progression of multiple malignant tumors. Nonetheless, the functions of circRNAs in NSCLC remain unclear. To study new targets for the treatment of NSCLC, circRNA expression profiling was performed on NSCLC tissues and para-carcinoma nonmalignant tissues. RNA was isolated and used for circRNA sequencing. Biological studies were performed in vitro and in vivo to determine the functions of circRNAs in NSCLC, including their functions in cell proliferation and migration. How circRNAs function in NSCLC was explored to clarify the underlying regulatory mechanisms. We found that circUCP2 was upregulated in NSCLC tissues compared with neighboring nonmalignant tissues. circUCP2 promoted the proliferation and metastasis of NSCLC cells. circUCP2 promoted NSCLC progression by sponging miR-149 and upregulating UCP2. The circUCP2/miR-149/UCP2 axis accelerates the progression of NSCLC, and circUCP2 may therefore be a novel diagnostic biomarker for the progression of NSCLC.

CircRNA hsa_circ_0000043 acts as a miR-4492 sponge to promote lung cancer progression via BDNF and STAT3 expression regulation in anti-benzo[a]pyrene-trans-7,8-dihydrodiol-9,10-epoxide-transformed 16HBE cells

Increasing evidence shows that circular RNA (circRNA) plays an important role in the progression of lung cancer. In this study, we found that has_circ_0000043 was highly expressed in 16HBE-T human bronchial epithelial cells that were malignantly transformed by benzo[a]pyrene-trans-7,8-diol-9,10-epoxide via circRNA microarray. We verified that hsa_circ_0000043 was also significantly overexpressed in lung cancer cell lines and tissues. Moreover, hsa_circ_0000043 overexpression was positively correlated with poor clinicopathological parameters, such as tumor-node metastasis stage, distant metastasis, lymph-node metastasis, and overall survival. In vitro assays revealed that hsa_circ_0000043 inhibition suppressed 16HBE-T cell proliferation, migration, and invasion. Furthermore, hsa_circ_0000043 inhibition suppressed tumor growth in a mouse xenograft model. We discovered that hsa_circ_0000043 binds with miR-4492, acting as a miR-4492 sponge. Decreased miR-4492 expression was also associated with poor clinicopathological parameters. Thus, hsa_circ_0000043 was shown to contribute to the proliferation, malignant transformation ability, migration, and invasion of 16HBE-T cells via miR-4492 sponging and BDNF and STAT3 involvement.

Circular RNA hsa_circ_0049657 as a Potential Biomarker in Non-Small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) is a common lung disorder. In this study, we applied bioinformatics methods to analyze and investigate the role of the NFIX gene in NSCLC. Hsa_circ_0049657 is derived from the NFIX gene, this research aimed to verify the potential role of hsa_circ_0049657 in the development of NSCLC. The results suggested that NFIX was downregulated in most cancers. In addition, the NFIX expression in lung adenocarcinoma (LUAD) was associated with the clinicopathological stage. In LUAD, NFIX expression was associated with the degree of infiltration of most immune cells. The expression levels of hsa_circ_0049657 were significantly lower in cancerous tissues than in paracancerous tissues. Moreover, the results showed that hsa_circ_0049657 expression was downregulated in NSCLC cells. After overexpression of hsa_circ_0049657, the proliferation and migration ability of NSCLC cells were significantly inhibited and the level of apoptosis was increased. We could suppress the proliferation and invasion abilities and promote apoptosis of NSCLC cells by up-regulating hsa_circ_0049657, which might be a potential biomarker for NSCLC.

Smart Nanocarriers for the Targeted Delivery of Therapeutic Nucleic Acid for Cancer Immunotherapy

A wide variety of therapeutic approaches and technologies for delivering therapeutic agents have been investigated for treating cancer. Recently, immunotherapy has achieved success in cancer treatment. Successful clinical results of immunotherapeutic approaches for cancer treatment were led by antibodies targeting immune checkpoints, and many have advanced through clinical trials and obtained FDA approval. A major opportunity remains for the development of nucleic acid technology for cancer immunotherapy in the form of cancer vaccines, adoptive T-cell therapies, and gene regulation. However, these therapeutic approaches face many challenges related to their delivery to target cells, including their in vivo decay, the limited uptake by target cells, the requirements for nuclear penetration (in some cases), and the damage caused to healthy cells. These barriers can be avoided and resolved by utilizing advanced smart nanocarriers (e.g., lipids, polymers, spherical nucleic acids, metallic nanoparticles) that enable the efficient and selective delivery of nucleic acids to the target cells and/or tissues. Here, we review studies that have developed nanoparticle-mediated cancer immunotherapy as a technology for cancer patients. Moreover, we also investigate the crosstalk between the function of nucleic acid therapeutics in cancer immunotherapy, and we discuss how nanoparticles can be functionalized and designed to target the delivery and thus improve the efficacy, toxicity, and stability of these therapeutics.

Fuzheng Kang-Ai inhibits NSCLC cell proliferation via regulating hsa_circ_0048091/hsa-miR-378g/ARRDC3 pathway

BACKGROUND

Current treatments for lung cancer have their own deficiencies, such as severe adverse effect. Therefore, more safe and effective drugs are needed.

PURPOSE

Fuzheng Kang-Ai (FZKA for short) has been applied as an adjuvant treatment in advanced Non-Small Cell Lung Cancer (NSCLC) patients for decades in China, showing a definitive effect with minimal toxicities. However, the underlying mechanism is yet to be identified.

STUDY DESIGN

Both in vitro and in vivo experiments were performed in this study to identify the exact mechanism by which FZKA inhibits NSCLC cell proliferation.

METHODS

MTT and CCK-8 assays were used to detect cell viability. Xenograft model was performed for in vivo experiments. CircRNA and miRNA sequencing were used to find the differentially expressed circRNAs and miRNAs, respectively. qRT-PCR was performed to check the expression levels of circRNA, miRNA and mRNA. BaseScope was carried out to observe the expression of circRNA in situ. Actinomycin D and RNase R experiments were done to show the stability of circRNA. Nuclear-cytoplasmic fractionation and FISH were used to identify the localization of circRNA and miRNA. Pull-down, RIP, and luciferase activity assays were performed to show the biding ability of circRNA, miRNA and target proteins. Flow cytometry was done to observe cell apoptosis. Western blot and IHC were done to detect the protein expression. TCGA database was used to analyze the survival rate.

RESULTS

FZKA inhibits NSCLC cell proliferation both in vitro and in vivo. Hsa_circ_0048091 and hsa-miR-378g were the most differentially expressed circRNA and miRNA, respectively, after FZKA treatment. Silencing hsa_circ_0048091 and overexpressing hsa-miR-378g promoted cell proliferation and reversed the inhibition effect of FZKA on NSCLC, respectively. Hsa-miR-378g was sponged by hsa_circ_0048091, and the overexpression of miR-378g reversed the inhibition effect of hsa_ circ_0048091 on NSCLC. ARRDC3, as a target of hsa-miR-378g, was increased by FZKA treatment. Silencing ARRDC3 reversed both the inhibition effect of FZKA and miR-378g inhibitor on NSCLC.

CONCLUSION

This study, for the first time, has established the function of hsa_circ_0048091, hsa- miR-378g, and ARRDC3 in lung cancer. It also shows that FZKA inhibits NSCLC cell proliferation through hsa_circ_0048091/hsa-miR-378g/ARRDC3 pathway, uncovering a novel mechanism by which FZKA controls human NSCLC cell growth.

The interplay between non-coding RNAs and alternative splicing: from regulatory mechanism to therapeutic implications in cancer

Alternative splicing (AS) is a common and conserved process in eukaryotic gene regulation. It occurs in approximately 95% of multi-exon genes, greatly enriching the complexity and diversity of mRNAs and proteins. Recent studies have found that in addition to coding RNAs, non-coding RNAs (ncRNAs) are also inextricably linked with AS. Multiple different types of ncRNAs are generated by AS of precursor long non-coding (pre-lncRNAs) or precursor messenger RNAs (pre-mRNAs). Furthermore, ncRNAs, as a novel class of regulators, can participate in AS regulation by interacting with the cis-acting elements or trans-acting factors. Several studies have implicated abnormal expression of ncRNAs and ncRNA-related AS events in the initiation, progression, and therapy resistance in various types of cancers. Therefore, owing to their roles in mediating drug resistance, ncRNAs, AS-related factors and AS-related novel antigens may serve as promising therapeutic targets in cancer treatment. In this review, we summarize the interaction between ncRNAs and AS processes, emphasizing their great influences on cancer, especially on chemoresistance, and highlighting their potential values in clinical treatment.

LncRNA BBOX1-AS1 targets miR-361-3p/COL1A1 axis to drive the progression of oesophageal carcinoma

BACKGROUND

Oesophageal carcinoma (EC) is one of the types of prevalent malignant cancer in the globe. Many researchers reported the vital role played by long-coding RNAs in EC. In the current research, we investigated the mechanisms of the action of lncRNA BBOX1-AS1 in EC progression.

METHODS

In EC tissues and EC cells, the expression levels of miR-361-3p along with COL1A1 and BBOX1-AS1 were detected through RT-qPCR or western blotting. MiR-361-3p interactions with BBOX1-AS1 or COL1A1 were verified through Luciferase reporter and RIP tests. Loss of function combined with caspase-3 activity, CCK-8 and Transwell assays was performed to investigate cell apoptosis, proliferation and migration, respectively. Knockdown of BBOX1-AS1 was used for evaluating BBOX1-AS1 effects on tumour development in vivo.

RESULTS

BBOX1-AS1 was remarkably elevated in EC tissues and cells. In addition, the silencing of BBOX1-AS1 attenuated the cell viability, cell migration and enhanced cell apoptosis of EC, as well as suppressed EC tumour formation in vivo. Moreover, BBOX1-AS1 was found to be a sponge of miR-361-3p, which downregulated miR-361-3p expression. MiR-361-3p inhibitor rescued the anti-tumour effect of BBOX1-AS1 knockdown on the progression of EC. Furthermore, we discovered that miR-361-3p specially bound to COL1A1 3'UTR and downregulated COL1A1 and COL1A1 reduction declined the promoting effect of silencing miR-361-3p on EC cell malignant phenotypes.

CONCLUSION

BBOX1-AS1 facilitated the EC development and malignancy via miR-361-3p/COL1A1 axis, indicating BBOX1-AS1 could be a novel therapy target for the diagnostic of EC.

The functional role of circular RNAs in the pathogenesis of retinoblastoma: a new potential biomarker and therapeutic target?

Retinoblastoma (RB) is a common cancer in infants and children. It is a curable disease; however, a delayed diagnosis or treatment makes the treatment difficult. Genetic mutations have a central role in the pathogenesis of RB. Genetic materials such as RNAs (coding and non-coding RNAs) are also involved in the progression of the tumor. Circular RNA (circRNA) is the most recently identified RNA and is involved in regulating gene expression mainly through "microRNA sponges". The dysregulation of circRNAs has been observed in several diseases and tumors. Also, various studies have shown that circRNAs expression is changed in RB tissues. Due to their role in the pathogenesis of the disease, circRNAs might be helpful as a diagnostic or prognostic biomarker in patients with RB. In addition, circRNAs could be a suitable therapeutic target to treat RB in a targeted therapy approach.

CircRNAs and RNA-Binding Proteins Involved in the Pathogenesis of Cancers or Central Nervous System Disorders

Circular RNAs (circRNAs), a newly recognized group of noncoding RNA transcripts, have established widespread attention due to their regulatory role in cell signaling. They are covalently closed noncoding RNAs that form a loop, and are typically generated during the splicing of precursor RNAs. CircRNAs are key post-transcriptional and post-translational regulators of gene expression programs that might influence cellular response and/or function. In particular, circRNAs have been considered to function as sponges of specific miRNA, regulating cellular processes at the post-transcription stage. Accumulating evidence has shown that the aberrant expression of circRNAs could play a key role in the pathogenesis of several diseases. Notably, circRNAs, microRNAs, and several RNA-binding proteins, including the antiproliferative (APRO) family proteins, could be indispensable gene modulators, which might be strongly linked to the occurrence of diseases. In addition, circRNAs have attracted general interest for their stability, abundance in the brain, and their capability to cross the blood-brain barrier. Here, we present the current findings and theragnostic potentials of circRNAs in several diseases. With this, we aim to provide new insights to support the development of novel diagnostic and/or therapeutic strategies for these diseases.

Circular RNA circDLG1 (has_circ_0068706) functions as an oncogene in nonsmall cell lung cancer through regulating AKT/mTOR signaling and direct binding to miR-144

Nonsmall cell lung cancer (NSCLC) is a major subtype of lung cancer, causing substantial cancer-related deaths worldwide. However, the molecular basis of NSCLC development and progression remains understudied. Recently, a circular RNA, circDLG1, has been implicated in carcinogenesis and cancer metastasis. Yet, how circDLG1 affects NSCLC progression has not been reported. Here this study aims to elucidate the role of circDLG1 in NSCLC. First, we found that circDLG1 was significantly upregulated in both the GEO dataset and NSCLC tissues. Next, we silenced the expression of circDLG1 in NSCLC cell lines. Knockdown of circDLG1 upregulated miR-144 and downregulated Protein kinase B (AKT)/mechanistic target of rapamycin (mTOR), resulting in suppression of the proliferation activity and metastasis ability of NSCLC. In addition, circDLG1 knockdown significantly decreased the expression of the mesenchymal markers, proliferating cell nuclear antigen (PCNA), and N-cadherin, while increasing the expression level of E-cadherin. In conclusion, we demonstrate that circDLG1 promotes the pathogenesis and progression of NSCLC by regulating the miR-144/AKT/mTOR signaling axis, providing potential diagnostic and therapeutic targets for designing innovative treatment strategies.

circGRAMD1B contributes to migration, invasion and epithelial-mesenchymal transition of lung adenocarcinoma cells via modulating the expression of SOX4

Lung adenocarcinoma (LUAD) represents the subtype of non-small-cell lung cancer (NSCLC), with the high morbidity over the world. Mounting studies have highlighted the important roles of circular RNAs (circRNA) in cancers, including LUAD. This study mainly focused on revealing the role of circGRAMD1B and its relevant regulatory mechanism in LUAD cells. RT-qPCR and Western blot were conducted to detect the expression of target genes. Function assays were performed to determine the effect of related genes on migration, invasion, and epithelial-mesenchymal transition (EMT) of LUAD cells. Mechanism analyses were conducted to figure out the specific mechanism with regard to circGRAMD1B and its downstream molecules as well. Based on the experimental results, circGRAMD1B was upregulated in LUAD cells and promoted the migration, invasion, and EMT of LUAD cells. Mechanically, circGRAMD1B sponged miR-4428 to upregulate the expression of SOX4. In addition, SOX4 activated the expression of MEX3A at the transcriptional level, thereby modulating PI3K/AKT pathway to facilitate LUAD cell malignant behaviors. In conclusion, circGRAMD1B is discovered to modulate miR-4428/SOX4/MEX3A axis to further activate PI3K/AKT pathway, finally boosting migration, invasion, and EMT of LUAD cells.

Circular RNAs: New layer of complexity evading breast cancer heterogeneity

Advances in high-throughput sequencing techniques and bioinformatic analysis have refuted the "junk" RNA hypothesis that was claimed against non-coding RNAs (ncRNAs). Circular RNAs (circRNAs); a class of single-stranded covalently closed loop RNA molecules have recently emerged as stable epigenetic regulators. Although the exact regulatory role of circRNAs is still to be clarified, it has been proven that circRNAs could exert their functions by interacting with other ncRNAs or proteins in their own physiologically authentic environment, regulating multiple cellular signaling pathways and other classes of ncRNAs. CircRNAs have also been reported to exhibit a tissue-specific expression and have been associated with the malignant transformation process of several hematological and solid malignancies. Along this line of reasoning, this review aims to highlight the importance of circRNAs in Breast Cancer (BC), which is ranked as the most prevalent malignancy among females. Notwithstanding the substantial efforts to develop a suitable anticancer therapeutic regimen against the heterogenous BC, inter- and intra-tumoral heterogeneity have resulted in an arduous challenge for drug development research, which in turn necessitates the investigation of other markers to be therapeutically targeted. Herein, the potential of circRNAs as possible diagnostic and prognostic biomarkers have been highlighted together with their possible application as novel therapeutic targets.

Ferroptosis-associated circular RNAs: Opportunities and challenges in the diagnosis and treatment of cancer

Ferroptosis is an emerging form of non-apoptotic regulated cell death which is different from cell death mechanisms such as autophagy, apoptosis and necrosis. It is characterized by iron-dependent lipid peroxide accumulation. Circular RNA (circRNA) is a newly studied evolutionarily conserved type of non-coding RNA with a covalent closed-loop structure. It exhibits universality, conservatism, stability and particularity. At present, the functions that have been studied and found include microRNA sponge, protein scaffold, transcription regulation, translation and production of peptides, etc. CircRNA can be used as a biomarker of tumors and is a hotspot in RNA biology research. Studies have shown that ferroptosis can participate in tumor regulation through the circRNA molecular pathway and then affect cancer progression, which may become a direction of cancer diagnosis and treatment in the future. This paper reviews the molecular biological mechanism of ferroptosis and the role of circular RNA in tumors and summarizes the circRNA related to ferroptosis in tumors, which may inspire research prospects for the precise prevention and treatment of cancer in the future.

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.

Whole Blood-Derived circUSP10 Acts as a Diagnostic Biomarker in Patients With Early-Stage Non-Small-Cell Lung Cancer

Accumulating evidence has indicated that differentially expressed noncoding circular RNAs (circRNAs) play essential roles in the occurrence and development of various types of cancer. Here, we aimed to identify and explore the diagnostic value of hsa_circ_0003026 (named circUSP10) in patients with early non-small-cell lung cancer (NSCLC). The differentially expressed circRNAs were screened from the microarray-based assay of human NSCLC tissues and their corresponding noncancerous tissues, and the candidate circRNAs were further verified in patients with NSCLC using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Circulating circUSP10 was isolated from whole blood of healthy people and patients with NSCLC and was detected by RT-qPCR. In addition, the diagnostic value of circUSP10 in early NSCLC was evaluated by receiver operating characteristic (ROC) curve analysis. We found that circUSP10 was upregulated in tumor tissues from patients with early NSCLC and associated with tumor size and tumor-node-metastasis (TNM) stage. Importantly, circUSP10 was obviously upregulated in the whole blood of patients with NSCLC. Additionally, whole blood-derived circUSP10 showed good diagnostic performance for screening early NSCLC and was relatively stable in blood under adverse conditions. These findings demonstrate that circUSP10 may act as a novel biomarker for the diagnosis of early-stage NSCLC, suggesting the potential of circUSP10 in RNA-based therapy for cancer.

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.

Oncogenic lncRNA BBOX1-AS1 promotes PHF8-mediated autophagy and elicits sorafenib resistance in hepatocellular carcinoma

Some long non-coding RNAs (lncRNAs) have been documented to be involved in cancer progression and anticancer drug resistance in hepatocellular carcinoma (HCC). Thus, approaches designed to target these genes may facilitate the development of promising strategies for treating HCC. Previously, we showed that lncRNA BBOX1-AS1 was highly expressed and played an oncogenic role in HCC. However, the potential functions and mechanisms through which BBOX1-AS1 regulates HCC progression and drug resistance remain unclear. This study revealed that BBOX1-AS1 could promote tumor progression, autophagy, and drug resistance by upregulating PHF8 in HCC cells. Mechanistically, BBOX1-AS1 enhanced the stability of PHF8 mRNA by targeting the PHF8 inhibitor miR-361-3p to regulate tumor progression and autophagy in HCC. The functional rescue experiments showed that PHF8 acted as a key factor in regulating the biological effects induced by BBOX1-AS1 and miR-361-3p in HCC, indicating that BBOX1-AS1 promotes tumor progression and sorafenib resistance by regulating miR-361-3p/PHF8. Finally, mouse tumor models and patient-derived organoid models were established to further confirm these findings. Taken together, the results demonstrate that BBOX1-AS1 promotes HCC progression and sorafenib resistance via the miR-361-3p/PHF8 axis.

circPOLR1C Promotes the Development of Esophageal Cancer by Adsorbing miR-361-3p and Regulating Cancer Cell Apoptosis and Metastasis

Background

The effect of circular RNA-RNA polymerase I and III subunit C (circPOLR1C) on esophageal cancer (EC) has not been reported. Herein, this study is designed to unveil the effect and the regulatory mechanism of circPOLR1C on EC.

Methods

The expression of circPOLR1C in EC tissues and cells was detected by qRT-PCR. Circular structure, stability, and cell localization of circPOLR1C were confirmed by qRT-PCR, RNase R, actinomycin D, and fluorescence in situ hybridization (FISH) assay. Cell function experiments, nude mouse xenograft, lung transplant model, and HE staining were performed to evaluate the effects of CircPOLR1C on EC in vitro and in vivo. A regulatory relationship between miR-361-3p and circPOLR1C was confirmed by qRT-PCR, circRNA in vivo precipitation, RIP, FISH, CircInteractome database, dual-luciferase reporter assay, and immunohistochemistry. Rescue experiments were applied to assess the effects of miR-361-3p and circPOLR1C on EC cells and tissues. Apoptosis- and epithelial-mesenchymal transformation (EMT)-related gene expressions were quantified by qRT-PCR and Western blot.

Results

Highly expressed circPOLR1C in EC was related to tumor differentiation and invasion. circPOLR1C, which mainly exists in the cytoplasm, is a stable circular RNA. circPOLR1C silencing inhibited circPOLR1C expression and EC cell malignant function, while circPOLR1C overexpression promoted the growth of transplanted tumors and lung metastasis. The enrichment of miR-361-3p was higher than that of other targeted miRNAs. circPOLR1C adsorbed miR-361-3p to regulate apoptosis- and EMT-related genes and partially reversed the tumor suppressive effect of miR-361-3p, which was lowly expressed in EC tissues. Silencing the target genes of miR-361-3p also inhibited the malignant development of EC cells.

Conclusion

circPOLR1C adsorbs miR-361-3p and regulates apoptosis- and EMT-related gene expressions to promote the development of EC.

Role of circular RNAs in retinoblastoma

Retinoblastoma (RB), the most common malignant retinal tumor among children under 3 years old, is lethal if left untreated. Early diagnosis, together with timely and effective treatment, is important to improve retinoblastoma-related outcomes. Circular RNAs (circRNAs), a new class of non-coding RNAs with the capacity to regulate cellular activities, have great potential in retinoblastoma diagnosis and treatment. Recent studies have identified circular RNAs that regulate multiple cellular processes involved in retinoblastoma, including cell viability, proliferation, apoptosis, autophagy, migration, and invasion. Six circular RNAs (circ-FAM158A, circ-DHDDS, circ-E2F3, circ-TRHDE, circ-E2F5, and circ-RNF20) promote disease progression and metastasis in retinoblastoma and function as oncogenic factors. Other circular RNAs, such as circ-TET1, circ-SHPRH, circ-MKLN1, and circ-CUL2, play tumor suppressive roles in retinoblastoma. At present, the studies on the regulatory mechanism of circular RNAs in retinoblastoma are not very clear. The purpose of this review is to summarize recent studies on the functional roles and molecular mechanisms of circular RNAs in retinoblastoma and highlight novel strategies for retinoblastoma diagnosis, prognosis, and treatment.

CircRNA has_circ_0017109 promotes lung tumor progression via activation of Wnt/β-catenin signaling due to modulating miR-671-5p/FZD4 axis

INTRODUCTION

Accumulating evidence highlights the critical roles of circular RNAs (circRNAs) in the malignant progression of cancers. In this study, we investigated the expression pattern of a newly identified circRNA (hsa_circ_0017109) in non-small cell lung cancer (NSCLC), and examined its downstream molecular targets.

METHODS

Quantitative real-time PCR (qRT-PCR) and Western blotting (WB) were conducted to quantify gene and protein expression. In vitro functional assays such as colony formation assay, cell counting kit-8 (CCK-8) and flow cytometry were used to study cell proliferation and apoptosis. RNA pull-down assay, luciferase reporter assay and RNA immunoprecipitation were performed to validate molecular interaction. Mouse xenograft model of NSCLC cells was used to assess the role of circ_0017109 in tumorigenesis.

RESULTS

Circ_0017109 was upregulated in NSCLC tumor samples and cells. Silencing circ_0017109 impaired cell proliferation and promoted apoptosis in NSCLC cells, and circ_0017109 knockdown suppressed in vivo tumorigenesis of NSCLC cells in mouse xenograft model. MiR-671-5p was identified as a target of circ_0017109, and circ_0017109 negatively impacted on miR-671-5p expression. MiR-671-5p downregulated FZD4 and dampened the activity of Wnt/β-catenin signaling pathway. Circ_0017109 modulated FZD4 expression by suppressing miR-671-5p activity.

CONCLUSIONS

Elevated circ_0017109 expression promotes tumor progression of NSCLC by modulating miR-671-5p/FZD4/β-catenin axis.