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

CircNUP98 promotes the malignant behavior of glioma cells through the miR-520f-3p/ELK4 axis

Glioma, a formidable form of brain cancer, poses significant challenges in terms of treatment and prognosis. Circular RNA nucleoporin 98 (circNUP98) has emerged as a potential regulator in various cancers, yet its role in glioma remains unclear. Here, we elucidate the functional role of circNUP98 in glioma cell proliferation, invasion, and migration, shedding light on its therapeutic implications. Glioma cells were subjected to si-NUP98 transfection, followed by assessments of cell viability, proliferation, invasion, and migration. Subcellular localization of circNUP98 was determined, and its downstream targets were identified. We delineated the binding relationships between circNUP98 and microRNA (miR)-520f-3p, as well as between miR-520f-3p and ETS transcription factor ELK4 (ELK4). The expression levels of circNUP98/miR-520f-3p/ELK4 were quantified. Our findings demonstrated that circNUP98 was upregulated in glioma cells, and its inhibition significantly attenuated glioma cell proliferation, invasion, and migration. Mechanistically, circNUP98 functioned as a sponge for miR-520f-3p, thereby relieving the inhibitory effect of miR-520f-3p on ELK4. Moreover, inhibition of miR-520f-3p or overexpression of ELK4 partially rescued the suppressive effect of circNUP98 knockdown on glioma cell behaviors. In summary, our study unveils that circNUP98 promotes glioma cell progression via the miR-520f-3p/ELK4 axis, offering novel insights into the therapeutic targeting of circNUP98 in glioma treatment.

Advanced strategies of targeting circular RNAs as therapeutic approaches in colorectal cancer drug resistance

Colorectal cancer (CRC) stands second in terms of mortality and third among the highest prevalent kinds of cancer globally. CRC prevalence is rising in moderately and poorly developed regions and is greater in economically advanced regions. Despite breakthroughs in targeted therapy, resistance to chemotherapeutics remains a significant challenge in the long-term management of CRC. Circular RNAs (circRNAs) have been involved in growing cancer therapy resistance, particularly in CRC, according to an increasing number of studies in recent years. CircRNAs are one of the novel subclasses of non-coding RNAs, previously thought of as viroid. According to studies, circRNAs have been recommended as biological markers for therapeutic targets and diagnostic and prognostic purposes. That is particularly notable given that the expression of circRNAs has been linked to the hallmarks of CRC since they are responsible for drug resistance in CRC patients; thereby, circRNAs are significant for chemotherapy failure. Moreover, knowledge concerning circRNAs remains relatively unclear despite using all these advanced techniques. Here, in this study, we will go over the most recent published work to highlight the critical roles of circRNAs in CRC development and drug resistance and highlight the main strategies to overcome drug resistance to improve clinical 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.

Circular RNA-mediated ceRNA network was identified in human lung adenocarcinoma by high-throughput sequencing

OBJECTIVES

Aberrantly expressed circular RNAs (circRNAs) have been detected in many types of tumors. Hence, they are currently investigated as candidate biomarkers for diagnostic and potential targets for therapy in cancers. The objective of this study was to assess the expression profile of circRNA in lung adenocarcinoma (LUAD).

METHODS

This study included 14 pairs of postoperative lung adenocarcinoma specimens, including cancer tissues and matched adjacent tissues. Second-generation sequencing was applied to the specimens to determine the circRNA expression in them among the 5242 distinct circRNAs detected.

RESULTS

We identified a total of 18 significantly dysregulated circRNAs in the LUAD tissues: upregulation in four and downregulation in 14. ROC (The receiver operating characteristic curve) further suggested that hsa_circ_0120106, has_circ_0007342, has_circ_0005937, and circRNA_0000826 could potentially be used as biomarkers in the diagnosis of LUAD. Furthermore, study of the circRNA-microRNA (miRNA)-messenger RNA (mRNA) revealed interactions between the 18 dysregulated circRNA and several cancer-related miRNAs. Finally, a further Kyoto Encyclopedia of Genes and Genomes analysis showed that the cell cycle phase transition, p53 signaling pathway, AMP-activated protein kinase (AMPK) relative signaling pathway, and so on were key putative pathways in the process of LUAD.

CONCLUSIONS

These findings demonstrated the correlation between abnormality in circRNA expression and LUAD, which lays the foundation of making CircRNAs candidate biomarkers in the diagnosis of LUAD.

CircRNA circ-PDCD11 is highly expressed in lung large-cell carcinoma and predicts poor survival

BACKGROUND

Circ-PDCD11 (hsa_circ_0019853, 461 bp) has been characterized as an oncogenic circRNA in breast cancer, while its function in other cancers is unclear. In this study, we explored the role of circ-PDCD11 in lung cancer.

METHODS

Plasma samples were obtained from patients with lung large-cell carcinoma (LLCC, n = 40), lung squamous cell carcinoma (LSCC, n = 40), lung adenocarcinoma (LA, n = 40) and small-cell lung cancer (SCLC, n = 40) as well as healthy controls (Control, n = 40). Paired tumor and nontumor tissue samples were obtained from all patients. Expression of circ-PDCD11 in these samples was determined by RT-qPCR. The role of plasma circ-PDCD11 in the diagnosis of LLCC was analyzed with ROC curve. A five-year follow-up was performed to analyze the role of plasma circ-PDCD11 in the prognosis of LLCC.

RESULTS

Plasma circ-PDCD11 was specifically upregulated in LLCC but not in other lung cancer types, compared to the controls. Increased circ-PDCD11 expression in tumor tissues compared to nontumor tissues was only observed in LLCC patients but not in other lung cancer types. Increased plasma circ-PDCD11 levels effectively separated LLCC patients from patients with other types of cancers. High plasma circ-PDCD11 levels were closely correlated with poor survival of LLCC patients. Plasma circ-PDCD11 levels were closely correlated with tumor metastasis, but not tumor size of LLCC.

CONCLUSION

CircRNA circ-PDCD11 is highly expressed specifically in LLCC and predicts poor survival.

Circular RNA in Retina: A Potential Biomarker and Therapeutic Target

Circular RNA (circRNA) is a newly discovered noncoding RNA, which forms a closed ring with more than 200 bases in length. CircRNA is formed by back splicing of precursor RNA, and its expression abundance in body fluid is up to 10 times that of homologous linear transcripts. Recently, novel activities for circRNA in various diseases have emerged, ranging from cancer therapy and neurodegenerative diseases. Here, we reviewed the literature on the biogenesis of circRNA and its relationship with retinal diseases in recent years. We first described the mechanism, existing form and main function of circRNA. Next, we also pinpoint that circRNA has great value in the diagnosis and treatment of retinal diseases represented by retinoblastoma, retinal degeneration, and diabetic retinopathy. By this review, we hope to explore more possibilities of circRNA in clinical diagnosis and treatment.

Dual role of quercetin in enhancing the efficacy of cisplatin in chemotherapy and protection against its side effects: a review

Chemotherapy has opened a new window in cancer therapy. However, the resistance of cancer cells has dramatically reduced the efficacy of chemotherapy. Cisplatin is a chemotherapeutic agent and its potential in cancer therapy has been restricted by resistance of cancer cells. As a consequence, the scientists have attempted to find new strategies in elevating chemotherapy efficacy. Due to great anti-tumour activity, naturally occurring compounds are of interest in polychemotherapy. Quercetin is a flavonoid with high anti-tumour activity against different cancers that can be used with cisplatin to enhance its efficacy and also are seen to sensitise cancer cells into chemotherapy. Furthermore, cisplatin has side effects such as nephrotoxicity and ototoxicity. Administration of quercetin is advantageous in reducing the adverse effects of cisplatin without compromising its anti-tumour activity. In this review, we investigate the dual role of quercetin in enhancing anti-tumour activity of cisplatin and simultaneous reduction in its adverse effects.

Hsa_circ_0129047 regulates the miR-375/ACVRL1 axis to attenuate the progression of lung adenocarcinoma

BACKGROUND

Circular RNAs (circRNAs) are attractive candidates to be used as biomarkers of human cancers, including lung adenocarcinoma (LUAD). Our study aimed to investigate the functions and regulatory mechanisms of hsa_circ_0129047 in the tumorigenesis of LUAD.

METHODS

Reverse transcription-quantitative polymerase chain reaction was performed to determine the circRNA, microRNA (miRNA), and mRNA expression levels in LUAD cell lines and tissues. Tumor xenografts were established in nude mice to evaluate whether hsa_circ_0129047 affected LUAD tumor development in vivo. Cell counting kit-8 and transwell assays were performed to assess the mechanisms by which hsa_circ_0129047 influenced the viability and migration of LUAD cells, respectively. Apoptosis was evaluated via determination of the levels of the apoptotic markers, B-cell lymphoma-2, and Bcl-2-associated X, via Western blotting. Dual-luciferase reporter assay, RNA immunoprecipitation assay, and Pearson's correlation analysis were performed to determine the relationships among miR-375 and hsa_circ_0129047 and activin A receptor-like type 1 (ACVRL1).

RESULTS

Downregulation of hsa_circ_0129047 levels was observed in LUAD cell lines and tissues. Meanwhile, the upregulation of hsa_circ_0129047 levels repressed the proliferative, migratory, and survival capacities of LUAD cells in vitro. Hsa_circ_0129047 exerted antitumor effects during in vivo tumor development. Finally, we demonstrated that hsa_circ_0129047 sponged miR-375. This interaction facilitated the expression of the downstream target of miR-375, ACVRL1, whose upregulation inhibited the development and malignancy of LUAD.

CONCLUSION

These findings demonstrate that hsa_circ_0129047 functions as a tumor inhibitor in LUAD by modulating the miR-375/ACVRL1 axis. Hence, hsa_circ_0129047 may be a promising biomarker and gene target for LUAD treatment.

Hsa_circ_0079530/AQP4 Axis Is Related to Non-Small Cell Lung Cancer Development and Radiosensitivity

Background: Circular RNAs are associated with non-small cell lung cancer (NSCLC) development and radiosensitivity. Nevertheless, the function and regulation mechanism of hsa_circ_0079530 (circ_0079530) in NSCLC development and radiosensitivity are largely unknown.

Methods: The abundances of circ_0079530, microRNA (miR-409-3p), aquaporin 4 (AQP4), E-cadherin, intercellular adhesion molecule-1, vitronectin, proliferating cell nuclear antigen, and matrix metalloproteinase 9 were determined via quantitative reverse transcription polymerase chain reaction or western blotting. Cell proliferation, survival fraction, cycle process, migration, invasion, and in vivo growth were examined by cell counting kit-8, colony formation, flow cytometry, transwell, and xenograft analyses. The binding relationship was assessed via dual-luciferase reporter assay and RNA immunoprecipitation assay.

Results: Circ_0079530 expression was increased in NSCLC tissues and radioresistant samples. Circ_0079530 knockdown restrained cell proliferation, migration, and invasion, and facilitated radiosensitivity. Circ_0079530 silence decreased tumor growth with or without radiation treatment. Circ_0079530 was verified as a miR-409-3p sponge, and miR-409-3p downregulation mitigated the effects of circ_0079530 interference on NSCLC cell malignancy and radiosensitivity. AQP4 was directly targeted by miR-409-3p. MiR-409-3p restrained cell proliferation, migration, and invasion, and enhanced radiosensitivity by decreasing AQP4 expression. Notably, circ_0079530 silence decreased AQP4 expression by regulating miR-409-3p expression.

Conclusion: Circ_0079530 silence repressed cell proliferation, migration, and invasion, and facilitated radiosensitivity in NSCLC cells by mediating miR-409-3p/AQP4 axis.

CircPCBP2 promotes the stemness and chemoresistance of DLBCL via targeting miR-33a/b to disinhibit PD-L1

Diffuse large B‐cell lymphoma (DLBCL) is the most common lymphoid malignancy with a high relapse rate of up to 40%. The prognosis of the disease needs improvement and requires a understanding of its molecular mechanism. We investigated the mechanisms of DLBCL development and its sensitivity to chemotherapy by focusing on circPCBP2/miR‐33a/b/PD‐L1 axis. Human DLBCL specimens and cultured cancer cell lines were used. Features of circPCBP2 were systematically characterized through Sanger sequencing, Actinomycin D, RNase R treatment, and FISH. The expression levels of circPCBP2, miR‐33a/b, PD‐L1, stemness‐related markers, ERK/AKT and JAK2/STAT3 signaling were measured using qRT‐PCR, western blotting, and immunohistochemistry. Stemness of DLBCL cells was assessed through spheroid formation assay and flow cytometry. Cell viability and apoptosis upon cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) treatment were determined using MTT assay and flow cytometry, respectively. Interactions of circPCBP2‐miR‐33a/b and miR‐33a/b‐PD‐L1 were validated using dual luciferase activity assay and RNA‐RIP. Nude mouse xenograft model was used to assess the function of circPCBP2 in DLBCL growth in vivo. circPCBP2 was upregulated in human DLBCL specimens and cultured DLBCL cells while miR‐33a/b was reduced. Knockdown of circPCBP2 or miR‐33a/b overexpression inhibited the stemness of DLBCL cells and promoted cancer cell apoptosis upon CHOP treatment. circPCBP2 directly bound with miR‐33a/b while miR‐33a/b targeted PD‐L1 3’‐UTR. circPCBP2 disinhibited PD‐L1 signaling via sponging miR‐33a/b. miR‐33a/b inhibitor and activating PD‐L1 reversed the effects of circPCBP2 knockdown and miR‐33a/b mimics, respectively. circPBCP2 knockdown restrained DLBCL growth in vivo and potentiated the anti‐tumor effects of CHOP. In conclusion, circPCBP2 enhances DLBCL cell stemness but suppresses its sensitivity to CHOP via sponging miR‐33a/b to disinhibit PD‐L1 expression. circPCBP2/miR‐33a/b/PD‐L1 axis could serve as a diagnosis marker or therapeutic target for DLBCL.

Circular GOLPH3 RNA exerts oncogenic effects in vitro by regulating the miRNA-1299/LIF axis in oral squamous cell carcinoma

Circular RNAs, which are a novel subclass of noncoding RNAs, are reported to be involved in various biological processes. Aberrant expression of circular RNAs may promote cancer progression. The function of circular GOLPH3 RNA (circGOLPH3) in oral squamous cell carcinoma (OSCC) is unclear. In this study, the circGOLPH3 levels in OSCC cell lines were determined using quantitative real-time polymerase chain reaction (qRT-PCR). Gain-of-function and loss-of-function experiments were performed to evaluate the roles of circGOLPH3 in OSCC. Cell counting kit 8, migration, and invasion assays were performed to determine the functions of circGOLPH3. The mechanism of circGOLPH3 in OSCC was investigated using qRT-PCR, western blotting, luciferase activity, and RNA pull-down analyses. Furthermore, the function of circGOLPH3 in vivo was evaluated. circGOLPH3 derived from GOLPH3 was mainly localized to the cytoplasm and exhibited high stability. The expression of circGOLPH3 was upregulated in OSCC cells. circGOLPH3 promoted the growth of OSCC in vitro and in vivo. Additionally, circGOLPH3 upregulated OSCC cell migration and invasion. Mechanistically, circGOLPH3 functioned as a microRNA sponge and downregulated miR-1299 expression. miR-1299 downregulated the expression of LIF by targeting its 3’-untranslated region. Inhibition of the circGOLPH3/miR-1299/LIF axis suppressed the growth, migration, and invasion of OSCC cells. These findings indicate that the circGOLPH3/miR-1299/LIF axis promotes OSCC cell growth, migration, and invasion and that this axis is a potential therapeutic target for OSCC.

hsa_circ_0077837 Alleviated the Malignancy of Non-Small Cell Lung Cancer by Regulating the miR-1178-3p/APITD1 Axis

Objective

circRNAs were a group of the most promising molecular biomarkers for clinical prognosis and diagnosis of non-small cell lung cancer (NSCLC). It was a pity that academic circle still struggled to figure out how circRNAs acted on NSCLC. This article aimed to study the function and mechanism of hsa_circ_0077837 in NSCLC progression.

Methods

Cell viability was measured via CCK-8, while apoptosis was evaluated with flow cytometry. The transwell assay and scratch test were used to detect invasion and migration, respectively. The dual-luciferase reporter gene assay verified the regulatory effect of miR-1178-3p on hsa_circ_0077837 and miR-1178-3p on apoptosis-inducing, TAF9-like domain 1 (APITD1). The TUNEL assay and immunohistochemistry were used to assess cells apoptosis and proliferation in lung tumor tissues in mice.

Results

Hsa_circ_0077837 and APITD1 expression were suppressed in NSCLC tissues and cells, and miR-1178-3p level was promoted. High amount of hsa_circ_0077837 intensely prevented cell proliferation, migration, and invasion, promoted cell apoptosis in vitro, and delayed tumor growth in mice. Further analysis indicated that hsa_circ_0077837 acted as a miR-1178-3p sponge to stabilize APITD1, the target of miR-1178-3p. Mechanistically, we discovered that hsa_circ_0077837 could prevent proliferation, viability, migration, and invasion of NSCLC cells through stimulating the miR-1178-3p/APITD1 pathway.

Conclusion

Collectively, our findings validated that hsa_circ_0077837 served as a miR-1178-3p sponge by targeting APITD1 that alleviated NSCLC progression.

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.

Non-Coding RNAs and Brain Tumors: Insights Into Their Roles in Apoptosis

A major terrifying ailment afflicting the humans throughout the world is brain tumor, which causes a lot of mortality among pediatric and adult solid tumors. Several major barriers to the treatment and diagnosis of the brain tumors are the specific micro-environmental and cell-intrinsic features of neural tissues. Absence of the nutrients and hypoxia trigger the cells’ mortality in the core of the tumors of humans’ brains: however, type of the cells’ mortality, including apoptosis or necrosis, has been not found obviously. Current studies have emphasized the non-coding RNAs (ncRNAs) since their crucial impacts on carcinogenesis have been discovered. Several investigations suggest the essential contribution of such molecules in the development of brain tumors and the respective roles in apoptosis. Herein, we summarize the apoptosis-related non-coding RNAs in brain tumors.

Identification of Novel CircRNA-miRNA-mRNA Regulatory Network and Its Prognostic Prediction in Breast Cancer

Aim

This study aimed to investigate the expression profiles of circRNAs and candidate circRNA-miRNA-mRNA network in BC.

Methods

Differentially expressed circRNAs, miRNAs, and mRNAs (DEcircRNAs, DEmiRNAs, and DEmRNAs) between BC and normal breast tissue samples were screened by analyzing raw data of the RNA sequencing profile. The expression levels of hub genes in 48 pairs of cancerous and tumor-free breast tissues surgically resected from BC patients were determined by RT-qPCR analysis.

Results

A total of 145 DEcircRNAs, 140 DEmiRNAs, and 2451 DEmRNAs between BC and normal breast tissue samples were screened out. There were 5 pairs of upcircRNA-downmiRNA-upmRNA network and 20 pairs of downcircRNA-upmiRNA-downmRNA network. EIF4EBP1, DUSP1, EGR2, EZH1, and CBX7 were found to be correlated with overall survival of the patients with BC. The expression level of EIF4EBP1 was increased and the expression levels of DUSP1, EGR2, EZH1, and CBX7 were decreased in cancerous breast tissues compared to tumor-free breast tissues (p < 0.0001). The RT-qPCR results from 48 BC patients were consistent with the bioinformatics results.

Conclusion

This study provides a novel perspective to study circRNA-miRNA-mRNA network in BC and assists in the identification of new potential biomarkers to be used for diagnostic and prognostic purposes.

Circular RNA regulates the onset and progression of cancer through the mitogen-activated protein kinase signaling pathway

The rapid increase in cancer morbidity and mortality worldwide is a major challenge for public health providers. Therefore, there is an urgent need to explore the molecular mechanism of tumorigenesis and identify potential diagnostic biomarkers and therapeutic methods. Circular RNA (circRNA) is characterized by a stable structure and tissue-specific expression; these features are useful in medical research and clinical applications. In recent years, with the development of high-throughput sequencing technology, the potential use of circRNA in cancer prognosis and treatment has been extensively explored. Abnormal circRNA expression interferes with specific signaling pathways such as the MAPK pathway; this phenomenon may provide potential diagnostic biomarkers and new therapeutic targets. The present article discusses the research progress on the regulatory roles of MAPK/ERK pathway-related circRNA molecules in the development and progression of different types of tumors. This review may provide insight into the development of circRNA-based cancer management strategies.

Circular RNA _0015278 inhibits the progression of non-small cell lung cancer through regulating the microRNA 1278/SOCS6 gene axis

Background

Non-small cell lung cancer (NSCLC) is one of the most lethal malignancies worldwide. Deepening understanding of the pathogenesis of NSCLC is quite important for its treatment. Circular (circ) RNA_0015278 has been found to be downregulated in NSCLC, but its role in NSCLC and the underlying regulatory mechanism is unknown.

Methods

Circ_0015278, microRNA (miR)-1278 and SOCS6 were analyzed with real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) or western blot. Cell Counting Kit-8 (CCK-8) and 5-ethynyl-2'-deoxyuridine (EdU) staining were used to evaluate cell proliferation. The colony forming capacity and invasion of NSCLC cells were assessed with colony formation and transwell assays, respectively. The interaction among circ_0015278, miR-1278, and SOCS6 was evaluated using luciferase, receptor interacting protein (RIP), and RNA-pull down assays. Cell apoptosis was analyzed using flow cytometry. A subcutaneous NSCLC xenograft mouse model was established for evaluating circ_0015278-mediated effects on the growth of NSCLC in vivo.

Results

Circ_0015278 was downregulated in NSCLC tissues and cells, and its reduced expression indicated poor prognosis. Overexpression of circ_0015278 restrained the proliferation, colony formation, invasion, and epithelial-mesenchymal transition (EMT) of NSCLC cells and induced NSCLC cell apoptosis. Moreover, overexpression of circ_0015278 inhibited the growth of NSCLC in vivo. Mechanically, circ_0015278 acted as an miR-1278 sponge to reduce its quantity, and miR-1278 targeted SOCS6 to inhibit its expression in NSCLC cells. Circ_0015278 promoted SOCS6 expression by sponging miR-1,278 in NSCLC cells. Overexpression of circ_0015278 attenuated the malignant phenotypes of NSCLC through sponging miR-1278 and consequently promoting SOCS6 expression.

Conclusions

We demonstrated for the first time that circ_0015278 attenuated the progression of NSCLC via targeting the miR-1278/SOCS6 axis, which provides potential diagnostic biomarkers and therapeutic targets.

circRNA hsa_circ_0005909 Predicts Poor Prognosis and Promotes the Growth, Metastasis, and Drug Resistance of Non-Small-Cell Lung Cancer via the miRNA-338-3p/SOX4 Pathway

Background

Circular RNAs (circRNAs) are powerful factors in regulating various cancer behaviors. It has been manifested in previous researches that circular RNA hsa_circ_0005909 (circ_0005909) exhibits a regulatory function in osteosarcoma. However, there are no other studies on whether circ_0005909 displays potential functions on the progression of non-small-cell lung cancer (NSCLC).

Methods

RT-PCR was applied to examine the expression of circ_0005909 in NSCLC. To study the specific behaviors of NSCLC cells after circ_0005909 knockdown, cell counting kit-8 (CCK-8) assays, colony formation assays, Transwell assays, and xenograft tumor model assays were conducted. Bioinformatics and luciferase reporter assays were employed to study the association among circ_0005909, miRNA-338-3p, and SOX4.

Results

In this research, our group firstly showed that circ_0005909 expressions were distinctly increased in NSCLC specimens and cell lines. Clinical studies revealed that high circ_0005909 expressions were associated with poor prognosis of NSCLC patients. Functionally, knockdown of circ_0005909 was observed to suppress the proliferation, metastasis, and drug resistance of NSCLC cells. In the terms of mechanism, circ_0005909 could act as a sponge of miRNA-338-3p, and miRNA-338-3p could target SOX4. In addition, miRNA-338-3p inhibitors reversed the suppressor ability of circ_0005909 silence on NSCLC behaviors.

Conclusions

circ_0005909 promoted the progression of NSCLC via the modulation of the miRNA-338-3p/SOX4 axis, which may be a therapeutic target for NSCLC.

LINC00942 Promotes Tumor Proliferation and Metastasis in Lung Adenocarcinoma via FZD1 Upregulation

BACKGROUND

Long non-coding RNAs (lncRNAs) have been reported to play important roles in the progression of human cancers. Herein, bioinformatic analysis identified that LINC00942 was a highly overexpressed lncRNA in lung adenocarcinoma (LUAD). The present study aimed to explore the roles and possible molecular mechanisms of LINC00942 in LUAD.

METHODS

First, on the basis of TCGA database, the expression and prognosis of LINC00942 were analyzed in LUAD tissues. Then, si-LINC00942 was transfected into A549 and H1299 cells to knockdown the expression of LINC00942. Cell viability was detected by MTT assay. Flow cytometry was used to analyze cell apoptosis. The expressions of PCNA, Bax, Bcl-2, and wnt/β-catenin pathway proteins were detected by western blotting. Dual-luciferase reporter assay was used to evaluate the regulatory relationship between LINC00942 and miR-5006-5p, or miR-5006-5p and FZD1.

RESULTS

We discovered that LINC00942 was up-regulated in LUAD tissues compared with adjacent tissues. Besides, we found the increased LINC00942 expression was associated with poor survival. In addition, silencing of LINC00942 suppressed the proliferation, migration, invasion and facilitated the apoptosis of A549 and H1299 cells. Moreover, silencing of LINC00942 repressed the expression of PCNA, Bcl-2, and enhanced Bax expression in A549 and H1299 cells. Mechanically, LINC00942 exerted its effects via enhancing Wnt signaling. LINC00942 functioned as competing endogenous RNA (ceRNA) by binding to miR-5006-5p, upregulating the expression of FZD1, which was a direct target of miR-5006-5p.

CONCLUSION

Our findings indicated that LINC00942/miR-5006-5p/FZD1 axis played important roles in LUAD growth through enhancing Wnt signaling. LINC00942/miR-5006-5p/FZD1 axis might serve as a potential biomarker and therapeutic target for LUAD treatment.

Circular RNAs Interaction with MiRNAs: Emerging Roles in Breast Cancer

Despite significant advances in cancer therapy strategies, breast cancer is one of the most common and lethal malignancies worldwide. Characterization of a new class of RNAs using next-generation sequencing opened new doors toward uncovering etiopathogenesis mechanisms of breast cancer as well as prognostic and diagnostic biomarkers. Circular RNAs (circRNAs) are a novel class of RNA with covalently closed and highly stable structures generated primarily from the back-splicing of precursor mRNAs. Although circRNAs exert their function through various mechanisms, acting as a sponge for miRNAs is their primary mechanism of function. Furthermore, growing evidence has shown that aberrant expression of circRNAs is involved in the various hallmarks of cancers. This paper reviews the biogenesis, characteristics, and mechanism of functions of circRNAs and their deregulation in various cancers. Finally, we focused on the circRNAs roles as a sponge for miRNAs in the development, metastasis, angiogenesis, drug resistance, apoptosis, and immune responses of breast cancer.

Emerging role of circular RNAs in the pathobiology of lung cancer

Lung cancer is among the leading causes of cancer mortality and incidence in both sexes. Different classes of transcripts have been proposed as molecular markers in this type of cancer. Circular RNAs (circRNAs) are a group of transcripts with circular enclosed and stable configuration. These transcripts are stable in the blood, thus can be used as markers for detection of disorders. Moreover, dysregulation of circRNAs in the affected tissues of patients with different cancers shows their possible roles in the carcinogenesis. Several circRNAs including circPRKC1, circFGFR1, hsa-circ-0020123 and circTP63 have been found to be up-regulated in lung cancer samples. Meanwhile, cir-ITCH, hsa_circ_100395, hsa_circ_0033155, circRNF13, circNOL10, circ-UBR5, circPTK2 and circCRIM1 have been shown to be down-regulated in lung cancer tissues compared with noncancerous counterparts. Finally, prognostic values of circPRKC1, circFGFR1, has-circ-00120123, circTP63, circ_0067934, CDR1as, hsa_circRN_103809 and some other circRNAs have been appraised in lung cancer. In the current manuscript, we describe the impact and utility of circRNAs in the pathology of lung cancer.

Hsa_circ_0001073 targets miR-626/LIFR axis to inhibit lung cancer progression

Circular RNAs (circRNAs) are associated with lung cancer progression. However, it is unclear whether and how circRNA hsa_circ_0001073 (circ_0001073) are involved in lung cancer progression. circ_0001073, microRNA (miR)-626, and leukemia inhibitory factor receptor (LIFR) abundances were determined via quantitative reverse transcription polymerase chain reaction or western blot. Cell viability, invasion, and apoptosis were analyzed by cell counting kit-8, transwell analysis and flow cytometry, respectively. The target correlation was tested by dual-luciferase reporter analysis or RNA immunoprecipitation. Results showed that circ_0001073 abundance was down-regulated in lung cancer cells. circ_0001073 constrained cell viability and invasion and facilitated apoptosis in lung cancer cells. miR-626 was targeted via circ_0001073, and circ_0001073 inhibited lung cancer progression via reducing miR-626 expression. LIFR was targeted via miR-626, and miR-626 knockdown constrained cell viability and invasion and facilitated apoptosis in lung cancer cells via up-regulating LIFR. circ_0001073 increased LIFR expression via miR-626 in lung cancer cells. In conclusion, circ_0001073 represses lung cancer progression via miR-626/LIFR axis, indicating the potential value of circ_0001073 in lung cancer treatment.

Harnessing the epigenome to boost immunotherapy response in non-small cell lung cancer patients

The introduction of immune checkpoint inhibitor (ICI)-based therapy for non-oncogene addicted non-small cell lung cancer (NSCLC) has significantly transformed the treatment landscape of the disease. Inhibitors of the programmed cell death protein 1/programmed death-ligand 1 (PD-1/PD-L1) immune checkpoint axis, which were initially considered as a late-line treatment option, gradually became the standard of care as first-line treatment for subgroups of NSCLC patients. However, a significant fraction of patients either fails to respond or progresses after a partial response to ICI treatment. Thus, the identification of mechanisms responsible for innate and acquired resistance to immunotherapy within a rapidly evolving tumor microenvironment (TME) is urgently required, as is the identification of reliable predictive biomarkers beyond PD-L1 expression. The deregulation of the epigenome is a key driver of cancer initiation and progression, and it has also been shown to drive therapeutic resistance. Tumor education of infiltrating myeloid cells towards an immuno-suppressive phenotype as well as induction of T-cell dysfunction in the TME is also driven by epigenome reprogramming. As it stands and, given their dynamic nature, epigenetic changes in cancer and non-cancer cells represent an attractive target to increase immunotherapy activity in NSCLC. Accordingly, clinical trials of combinatorial immuno-epigenetic drug regimens have been associated with tumor response in previously immunotherapy-resistant NSCLC patients irrespective of their PD-L1 status. Moreover, epigenetic signatures might represent valuable theragnostic biomarkers as they can be assayed easily in liquid biopsy and provide multiple layers of information. In this review, we discuss the current knowledge regarding the dysregulated epigenetic mechanisms contributing to immunotherapy resistance in NSCLC. Although the clinical data are still maturing, we highlight the attractive perspective that the synergistic model of immuno-epigenetic strategies might overcome the current limitations of immunotherapy alone and will be translated into durable clinical benefit for a broader NSCLC population.

Non-coding RNAs and lipids mediate the function of extracellular vesicles in cancer cross-talk

Research on extracellular vesicles (EVs) has been expanded, especially in the field of cancer. The cargoes in EVs, especially those in small EVs such as exosomes include microRNAs (miRNAs), mRNA, proteins, and lipids, are assumed to work cooperatively in the tumor microenvironment. In 2007, it was reported that miRNAs were abundant among the non-coding RNAs present in exosomes. Since then, many studies have investigated the functions of miRNAs and have tried to apply these molecules to aid in the diagnosis of cancer. Accordingly, many reviews of non-coding RNAs in EVs have been published for miRNAs. This review focuses on relatively new cargoes, covering long noncoding (lnc) RNAs, circular RNAs, and repeat RNAs, among non-coding RNAs. These RNAs, regardless of EV or cell type, have newly emerged due to the innovation of sequencing technology. The poor conservation, low quantity, and technical difficulty in detecting these RNA types have made it difficult to elucidate their functions and expression patterns. We herein summarize a limited number of studies. Although lipids are major components of EVs, current research on EVs focuses on miRNA and protein biology, while the roles of lipids in exosomes have not drawn attention. However, several recent studies revealed that phospholipids, which are components of the EV membrane, play important roles in the intercommunication between cells and in the generation of lipid mediators. Here, we review the reported roles of these molecules, and describe their potential in cancer biology.

Circ_0093887 upregulates CCND2 and SUCNR1 to inhibit the ox-LDL-induced endothelial dysfunction in atherosclerosis by functioning as a miR-876-3p sponge

Circular RNAs (circRNAs) are widely expressed in mammals and act as regulatory targets in the atherogenesis. The objective of this study was to research the biological role and molecular mechanism of circ_0093887 in oxidized low-density lipoprotein (ox-LDL)-induced atherosclerosis (AS) of human aortic endothelial cells (HAECs). Cell viability detection was performed by CCK-8 assay. Inflammatory molecules were examined using ELISA. Flow cytometry was used to measure cell-cycle progression and cell apoptotic rate. Caspase 3 activity was determined using caspase 3 activity assay. The expression levels of circ_0093887, miR-876-3p, CCND2 and SUCNR1 were assayed by quantitative real-time polymerase chain reaction (qRT-PCR). Dual-luciferase reporter, RNA immunoprecipitation (RIP) and RNA pull-down assays were used for the target analysis. EdU assay, wound healing assay/transwell assay and tube formation assay were, respectively, used to assess the effects of circ_0093887/miR-876-3p axis on cell proliferation, migration and tube formation. Oxidized low-density lipoprotein inhibited cell viability and cell-cycle progression but induced the inflammatory response and cell apoptosis. Circ_0093887 was downregulated and miR-876-3p was upregulated in AS patients and ox-LDL-treated HAECs. Functionally, the overexpression of circ_0093887 abrogated the cell injury of HAEC exposed to ox-LDL. For the functional mechanism, we found that circ_0093887 was a sponge for miR-876-3p and miR-876 targeted CCND2 or SUCNR1. The reverted experiment indicated that the function of circ_0093887 was achieved by sponging miR-876-3p. Meanwhile, miR-876-3p inhibitor relieved the inhibitory regulation of circ_0093887 knockdown in cell proliferation, migration and tube formation. Downregulation of miR-876-3p also alleviated the ox-LDL-induced cell injury by upregulating the expression of CCND2 or SUCNR1. Furthermore, circ_0093887 was validated to regulate the levels of CCND2 and SUCNR1 via the sponge effect on miR-876-3p. The protective effects of circ_0093887 on HAECs from ox-LDL were also ​alleviated by repressing the CCND2 and SUCNR1 levels. These findings suggested that circ_0093887 protected HAEC against the ox-LDL-induced inflammatory and apoptotic damages by targeting the miR-876-3p/CCND2 or miR-876/SUCNRA axis. Circ_0093887 could act as a potential therapeutic biomarker for AS patients.

Emerging landscape of circHIPK3 and its role in cancer and other diseases (Review)

Circular RNAs (circRNAs) are a special class of recently re‑discovered RNAs, which are covalently closed ring RNA molecules. circRNAs have been reported to possess multiple functions and are considered crucial regulators of several processes, and are therefore gaining increasing attention. In recent years, increasing evidence has shown that circRNAs are implicated in several crucial biological processes via regulation of gene expression, and their dysregulation is also associated with the development of numerous diseases, particularly acting as oncogenic or tumor‑suppressor molecules in cancer. Furthermore, circRNAs are involved in cell proliferation, differentiation, apoptosis, invasion and metastasis. In the present review, the biogenesis and functions of circRNAs are described, with a focus on the most recent research advances and the emerging roles of circular homeodomain‑interacting protein kinase 3 (circHIPK3) in human diseases. The present review may provide novel avenues for research on the roles of circHIPK3 as a clinical diagnostic and prognostic biomarker, as well as highlighting promising therapeutic targets for certain diseases and cancer.

CircRNA ZNF609 Knockdown Represses the Development of Non-Small Cell Lung Cancer via miR-623/FOXM1 Axis

Background

The dysregulated circular RNAs (circRNAs) are relevant to the development of non-small cell lung cancer (NSCLC). Nevertheless, the function and mechanism of circRNA zinc finger protein 609 (circZNF609) in NSCLC development remain uncertain.

Methods

Sixty-two NSCLC patients were recruited. circZNF609, microRNA-623 (miR-623) and forkhead box M1 (FOXM1) abundances were measured via quantitative reverse transcription polymerase chain reaction or Western blot. Cell viability, apoptosis, migration and invasion were analyzed via cell counting kit-8 (CCK8), flow cytometry, caspase3 activity, transwell assay and Western blot. The interaction between miR-623 and circZNF609 or FOXM1 was analyzed via dual-luciferase reporter analysis, RNA immunoprecipitation and pull-down. The function of circZNF609 on cell growth in vivo was tested via xenograft model.

Results

circZNF609 abundance was enhanced in NSCLC tissues and cells. High expression of circZNF609 indicated the lower overall survival. circZNF609 interference restrained cell viability, migration and invasion and increased apoptosis. miR-623 was targeted via circZNF609. FOXM1 was targeted via miR-623 and regulated via circZNF609. miR-623 knockdown or FOXM1 overexpression mitigated the role of circZNF609 silence in NSCLC development. circZNF609 knockdown decreased NSCLC xenograft tumor growth.

Conclusion

circZNF609 knockdown repressed NSCLC development via regulating miR-623 and FOXM1.

Propofol suppresses lung cancer tumorigenesis by modulating the circ-ERBB2/miR-7-5p/FOXM1 axis

BACKGROUND

Propofol is a commonly used anesthetic for cancer surgery. Previous studies have shown that propofol has an anticancer role in various cancers, including lung cancer. This study aimed to investigate the role of propofol in lung cancer and its underlying mechanism.

METHODS

Cell proliferation was determined by cell counting kit-8 (CCK-8) and colony formation assays. Flow cytometry and transwell assays were used to detect cell apoptosis and invasion, respectively. Glycolysis was evaluated by detecting glucose consumption, lactate production and ATP/ADP ratios. The levels of circular RNA erb-b2 receptor tyrosine kinase 2 (circ-ERBB2), microRNA-7-5p (miR-7-5p) and forkhead box M1 (FOXM1) were tested by quantitative real-time PCR and Western blot. The binding relationship between miR-7-5p and circ-ERBB2/FOXM1 was verified by dual-luciferase reporter assay. Moreover, in vivo experiments were performed by establishing a mouse xenograft model.

RESULTS

Propofol suppressed cell proliferation, invasion and glycolysis and expedited apoptosis in lung cancer cells. Circ-ERBB2 and FOXM1 were upregulated, while miR-7-5p was decreased in lung cancer tissues and cells. Propofol suppressed lung cancer cell progression by regulating circ-ERBB2. Additionally, miR-7-5p directly interacted with circ-ERBB2 and FOXM1. Also, propofol played an antitumor role in lung cancer via modulating miR-7-5p or FOXM1. Moreover, circ-ERBB2 knockdown enhanced the suppressive effect of propofol on tumor growth in vivo.

CONCLUSIONS

Propofol inhibited lung cancer progression via mediating circ-ERBB2/miR-7-5p/FOXM1 axis, which might provide an effective therapeutic target for lung cancer therapy.

Non-Coding RNAs in Diffuse Large B-Cell Lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma worldwide. The molecular mechanisms underlying DLBCL have not been fully elucidated, and approximately 40% of patients who undergo standard chemoimmunotherapy still present with primary refractory disease or relapse. Non-coding RNAs (ncRNAs), a group of biomolecules functioning at the RNA level, are increasingly recognized as vital components of molecular biology. With the development of RNA-sequencing (RNA-Seq) technology, accumulating evidence shows that ncRNAs are important mediators of diverse biological processes such as cell proliferation, differentiation, and apoptosis. They are also considered promising biomarkers and better candidates than proteins and genes for the early recognition of disease onset, as they are associated with relative stability, specificity, and reproducibility. In this review, we provide the first comprehensive description of the current knowledge regarding three groups of ncRNAs—microRNAs (miRNAs), circular RNAs (circRNAs), and long non-coding RNAs (lncRNAs)—focusing on their characteristics, molecular functions, as well as diagnostic and therapeutic potential in DLBCL. This review provides an exhaustive account for researchers to explore novel biomarkers for the diagnosis and prognosis of DLBCL and therapeutic targets.

Circ0001320 inhibits lung cancer cell growth and invasion by regulating TNFAIP1 and TPM1 expression through sponging miR-558

Lung cancer is the most affected malignant tumor in the world, and its specific pathogenesis is still unclear. It has been confirmed that circ0001320 is down-regulated in lung cancer, but its mechanism has not been reported. Further study found that circ0001320 was down-regulated in lung cancer cells, localized in the cytoplasm, and had multiple miR-558 binding sites. Dual-luciferase reporter gene assay, RNA-pull-down, and immunoprecipitation experiments all confirmed that circ0001320 directly bound to miR-558, and then inhibit the expression of miR-558. MiR-558 was up-regulated in lung cancer cells, and bound the downstream target genes TNFAIP1 and TPM1 to inhibit their expression. Western blot showed that circ0001320 significantly up-regulated the protein levels of TNFAIP1 and TPM1, while miR-558 blocked this effect of circ0001320. Circ0001320, TNFAIP1, and TPM1 all inhibited the proliferation and invasion of lung cancer cells and promoted apoptosis, while miR-558 had the opposite effects. After transfection with circ0001320 overexpression vector, miR-558 up-regulation or down-regulation of TNFAIP1, or TPM1 expression significantly reversed the inhibition of cell growth and invasion by circ0001320. Similarly, the expression of TNFAIP1 or TPM1 was down-regulated, while miR-558 expression was inhibited, and the levels of cell proliferation, apoptosis, and invasion did not change significantly. Therefore, these fully show that circ0001320 inhibits the growth and invasion of lung cancer cells through miR-558/TNFAIP1 and TPM1 pathways, which may be closely related markers and therapeutic targets of lung cancer.

Biological functions of long noncoding RNAs and circular RNAs in small-cell lung cancer

We aim to discuss comprehensively the role of long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs) in small-cell lung cancer (SCLC) biology and their clinical utility as cancer biomarkers. We searched the scientific literature to select articles related to the role of lncRNAs and circRNAs in SCLC biology or as cancer biomarkers. We identified that a number of lncRNAs and circRNAs can regulate key biological processes involved in SCLC development, including cell proliferation, metastasis and chemoresistance mainly acting as miRNA sponges. Also, the expression of a few lncRNAs and circRNAs predicted survival outcome depicting their utility as prognostic biomarkers. Further investigations on the role of lncRNAs and circRNAs in SCLC tumors may yield novel therapeutic targets for SCLC.

Circ-PVT1/miR-106a-5p/HK2 axis regulates cell growth, metastasis and glycolytic metabolism of oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is the most commonly diagnosed oral cavity malignancy. A handful of circular RNAs (circRNAs) have recently shown to act as crucial regulators in OSCC, including circRNA plasmacytoma variant translocation 1 (circ-PVT1). However, further exploration is still needed for the underlying functional mechanism behind circ-PVT1 in OSCC. The levels of circ-PVT1, microRNA-106a-5p (miR-106a-5p) and hexokinase II (HK2) were all examined applying with quantitative real-time polymerase chain reaction (qRT-PCR). Cellular analyses (cell viability, apoptosis, metastasis and glycolysis) in vitro were performed via cell counting kit-8 (CCK-8), flow cytometry, transwell migration/invasion assays and glycolysis-related indications (glucose consumption, lactate production and ATP/ADP ratio). HK2 protein level was measured through western blot. Dual-luciferase reporter assay was conducted to study the interplay between miR-106a-5p and circ-PVT1 or HK2. Xenografts in mice were used for analyzing circ-PVT1 in vivo. Circ-PVT1 was expressed with abnormal high level while miR-106a-5p was down-regulated in OSCC tissues and cells. Circ-PVT1 knockdown reduced OSCC cell growth, metastasis and glycolysis. Moreover, circ-PVT1 acted in OSCC by functioning as a miR-106a-5p sponge. HK2 was a target of miR-106a-5p and miR-106a-5p played an anti-tumor role in OSCC by inhibiting HK2. Furthermore, HK2 could be regulated by circ-PVT1 via targeting miR-106a-5p. In xenograft models of mice, down-regulation of circ-PVT1 retarded tumorigenesis via the miR-106a-5p/HK2 axis. Our works suggested that circ-PVT1 directly combined with miR-106a-5p to mediate HK2 level, consequently regulating cellular behaviors in OSCC as a tumor promoter.

Recent advances in understanding circular RNAs

Exonic circular RNAs (circRNAs) have been discovered in all kingdoms of life. In many cases, the details of circRNA function and their involvement in cellular processes and diseases are not yet fully understood. However, the past few years have seen significant developments in bioinformatics and in experimental protocols that advance the ongoing research in this still-emerging field. Sophisticated methods for circRNA generation in vitro and in vivo have been developed, allowing model studies into circRNA function and application. We here review the ongoing circRNA research, giving special attention to recent progress in the field.

circ_0007385 served as competing endogenous RNA for miR-519d-3p to suppress malignant behaviors and cisplatin resistance of non-small cell lung cancer cells

Background

Circular RNAs (circRNAs) have been closely implicated in competing endogenous RNA (ceRNA) network among human cancers including non‐small cell lung cancer (NSCLC). However, the role of most circRNAs in NSCLC remains to be determined. Here, we aimed to investigate the role of hsa_circ_0007385 (circ_0007385) in NSCLC cells.

Methods

Expression of hsa_circ_0007385 (circ_0007385), miRNA (miR)‐519d‐5p and high‐mobility group box 1 (HMGB1) was measured by real‐time quantitative PCR and western blotting. Functional experiments were evaluated by cell counting kit (CCK)‐8, flow cytometry, fluorescein active caspase‐3 staining kit, transwell assays, western blotting, and xenograft experiment. The relationship among circ_0007385,miR‐519d‐5p and HMGB1 was testified by dual‐luciferase reporter assay. Kaplan‐Meiersurvival curve identified overall survival in NSCLC patients.

Results

circ_0007385 expression was higher in NSCLC tissues and cell lines, and was associated with poor overall survival. Silencing circ_0007385 could suppress cell proliferation, migration and invasion in A549 and H1975 cells, as well as cisplatin (DDP) resistance. Moreover, circ_0007385 silence retarded tumor growth of A549 cells in vivo. Molecularly, there was a direct interaction between miR‐519d‐3p and either circ_0007385 or HMGB1; expression of miR‐519d‐3p was downregulated in NSCLC tumors in a circ_0007385‐correlated manner, and circ_0007385 could indirectly regulate HMGB1 via miR‐519d‐3p. Functionally, both inhibiting miR‐519d‐3p and restoring HMGB1 could overturn the suppressive effect of circ_0007385 knockdown on cell proliferation, migration, invasion, and DDP resistance.

Conclusions

Collectively, circ_0007385 deletion could function anti‐tumor role in NSCLC by suppressing malignant behaviors and DDP resistance in vitro and in vivo via circ_0007385/miR‐519d‐3p/HMGB1 axis. These outcomes might enhance our understanding of the molecular mechanisms underlying the malignant progression of NSCLC.

Key points

Significant findings of the study

circ_0007385 was upregulated in NSCLC tissues and cells, and was associated with poor overall survival.

Silenced circ_0007385 suppressed NSCLC cell proliferation, migration, invasion, and DDP resistance in vitro, and tumor growth in vivo.

circ_0007385 was upregulated in NSCLC tissues and cells, and was associated with poor overall survival.

What this study adds

miR‐519d‐3p could directly interact with circ_0007385 and HMGB1 in NSCLC cells.

A promising circ_0007385/miR‐519d‐3p/HMGB1 regulatory pathway was determined in NSCLC cells.