Hsa_circ_0002483 inhibited the progression and enhanced the Taxol sensitivity of non-small cell lung cancer by targeting miR-182-5p

DPMGCDA: Deciphering circRNA-Drug Sensitivity Associations with Dual Perspective Learning and Path-Masked Graph Autoencoder

Accumulating evidence has indicated that the expression of circular RNAs (circRNAs) can affect the cellular sensitivity to drugs and significantly influence drug efficacy. However, traditional experimental approaches for validating these associations are resource-intensive and time-consuming. To address this challenge, we propose a computational framework termed DPMGCDA leveraging dual perspective learning and path-masked graph autoencoder to predict circRNA-drug sensitivity associations. Initially, we construct circRNA-circRNA fusion similarity networks and drug-drug fusion similarity networks using similarity network fusion, ensuring a comprehensive integration of information. Based on the above, we built the circRNA homogeneous graph, the drug homogeneous graph, and the circRNA-drug heterogeneous graph. Next, we form the initial node features in the circRNA-drug heterogeneous graph from the homogeneous graph-level perspective and the combined feature-level perspective and complete the prediction of potential associations using the path-masked graph autoencoder in both perspectives. The predictions under both perspectives are finally combined to obtain the final prediction score. Transductive setting experiments and inductive setting experiments all demonstrate that our method, DPMGCDA, outperforms state-of-the-art approaches. Additionally, we verify the necessity of employing dual perspective learning through ablation tests and analyze the effective encoding capability of the path-masked graph autoencoder for features through embedding visualization. Moreover, case studies on four drugs corroborate DPMGCDA's ability to identify potential circRNAs associated with new drugs.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Hsa_circ_0092856 Promoted the Proliferation, Migration, and Invasion of NSCLC Cells by Up-Regulating the Expression of eIF3a

Circular RNA (circRNA) plays a very important regulatory role in a variety of human malignancies such as non-small-cell lung cancer (NSCLC). In the current study, we explored the role of hsa_circ_0092856 in the progression of NSCLC. We screened CircRNA from the eIF3a gene in the Circbase database. The biological functions of hsa_circ_0092856 in NSCLC were analyzed via qRT-PCR, a CCK-8 assay, a plate cloning experiment, scratch testing, a transwell chamber experiment, an RNA nuclear mass separation experiment, an RIP experiment, and a Western blot test. The results showed that hsa_circ_0092856 was highly expressed in NSCLC cells, and the knockdown of hsa_circ_0092856 could inhibit the proliferation, migration, and invasion of NSCLC cells. The overexpression of hsa_circ_0092856 has the opposite effect. The expression of eIF3a also changed with the change in hsa_circ_0092856. These results suggest that hsa_circ_0092856 may play a key role in the progression of NSCLC by regulating the expression of eIF3a.

Non-Coding RNAs as Key Regulators in Lung Cancer

For several decades, most lung cancer investigations have focused on the search for mutations in candidate genes; however, in the last decade, due to the fact that most of the human genome is occupied by sequences that do not code for proteins, much attention has been paid to non-coding RNAs (ncRNAs) that perform regulatory functions. In this review, we principally focused on recent studies of the function, regulatory mechanisms, and therapeutic potential of ncRNAs including microRNA (miRNA), long ncRNA (lncRNA), and circular RNA (circRNA) in different types of lung cancer.

FOXO1, a tiny protein with intricate interactions: Promising therapeutic candidate in lung cancer

Nowadays, lung cancer is the most common cause of cancer-related deaths in both men and women globally. Despite the development of extremely efficient targeted agents, lung cancer progression and drug resistance remain serious clinical issues. Increasing knowledge of the molecular mechanisms underlying progression and drug resistance will enable the development of novel therapeutic methods. It has been revealed that transcription factors (TF) dysregulation, which results in considerable expression modifications of genes, is a generally prevalent phenomenon regarding human malignancies. The forkhead box O1 (FOXO1), a member of the forkhead transcription factor family with crucial roles in cell fate decisions, is suggested to play a pivotal role as a tumor suppressor in a variety of malignancies, especially in lung cancer. FOXO1 is involved in diverse cellular processes and also has clinical significance consisting of cell cycle arrest, apoptosis, DNA repair, oxidative stress, cancer prevention, treatment, and chemo/radioresistance. Based on the critical role of FOXO1, this transcription factor appears to be an appropriate target for future drug discovery in lung cancers. This review focused on the signaling pathways, and molecular mechanisms involved in FOXO1 regulation in lung cancer. We also discuss pharmacological compounds that are currently being administered for lung cancer treatment by affecting FOXO1 and also point out the essential role of FOXO1 in drug resistance. Future preclinical research should assess combination drug strategies to stimulate FOXO1 and its upstream regulators as potential strategies to treat resistant or advanced lung cancers.

Serum Exosomes-Based Biomarker circ_0008928 Regulates Cisplatin Sensitivity, Tumor Progression, and Glycolysis Metabolism by miR-488/HK2 Axis in Cisplatin-Resistant Nonsmall Cell Lung Carcinoma

Background: Nonsmall cell lung carcinoma (NSCLC) is a major cause of cancer-related death worldwide. The resistance of NSCLC to chemical drugs, such as cisplatin (CDDP), poses a heavy burden for NSCLC therapy. Herein, the effects of circular_0008928 (circ_0008928) on the CDDP sensitivity and biological behavior of CDDP-resistant NSCLC cells and underlying mechanism are revealed. Materials and Methods: The expression of circ_0008928 and microRNA-488 (miR-488) was detected by quantitative real-time polymerase chain reaction. The expression of hexokinase 2 (HK2) protein and exosome-specific proteins was determined by Western blot. The half-maximal inhibitory concentration (IC50) value of CDDP was detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell proliferation and migratory and invasive abilities were illustrated by cell counting kit-8 and transwell assays. Cell glycolysis metabolism was illustrated by extracellular acidification rate assay, glucose kit and lactate kit assays and Western blot analysis. The binding sites between miR-488 and circ_0008928 or HK2 were predicted by starbase or microT-CDS online database, and identified by dual-luciferase reporter and RNA immunoprecipitation assays. Results: Circ_0008928 expression and HK2 protein expression were significantly upregulated, while miR-488 expression was obviously downregulated in NSCLC cells and CDDP-resistant NSCLC cells. Circ_0008928 expression was increased in serum exosomes of CDDP-resistant NSCLC patients compared with CDDP-sensitive NSCLC patients. In addition, circ_0008928 silencing improved CDDP sensitivity and attenuated CDDP-induced cell proliferation, migration, invasion, and glycolysis metabolism. Circ_0008928 was a sponge of miR-488, and miR-488 bound to HK2 in CDDP-resistant NSCLC cells. Furthermore, both miR-488 inhibitor and HK2 overexpression attenuated circ_0008928 absence-mediated impacts on CDDP sensitivity and tumor process in CDDP-resistant NSCLC. Conclusions: Circ_0008928 knockdown improved CDDP sensitivity and hindered cell proliferation, migration, invasion, and glycolysis metabolism by miR-488/HK2 axis in CDDP-resistant NSCLC. This finding provides a new mechanism for studying CDDP-resistant therapy in NSCLC.

Chemoresistance Mechanisms in Non-Small Cell Lung Cancer-Opportunities for Drug Repurposing

Globally, lung cancer contributes significantly to the public health burden-associated mortality. As this form of cancer is insidious in nature, there is an inevitable diagnostic delay leading to chronic tumor development. Non-small cell lung cancer (NSCLC) constitutes 80-85% of all lung cancer cases, making this neoplasia form a prevalent subset of lung carcinoma. One of the most vital aspects for proper diagnosis, prognosis, and adequate therapy is the precise classification of non-small cell lung cancer based on biomarker expression profiling. This form of biomarker profiling has provided opportunities for improvements in patient stratification, mechanistic insights, and probable druggable targets. However, numerous patients have exhibited numerous toxic side effects, tumor relapse, and development of therapy-based chemoresistance. As a result of these exacting situations, there is a dire need for efficient and effective new cancer therapeutics. De novo drug development approach is a costly and tedious endeavor, with an increased attrition rate, attributed, in part, to toxicity-related issues. Drug repurposing, on the other hand, when combined with computer-assisted systems biology approach, provides alternatives to the discovery of new, efficacious, and safe drugs. Therefore, in this review, we focus on a comparison of the conventional therapy-based chemoresistance mechanisms with the repurposed anti-cancer drugs from three different classes-anti-parasitic, anti-depressants, and anti-psychotics for cancer treatment with a primary focus on NSCLC therapeutics. Certainly, amalgamating these novel therapeutic approaches with that of the conventional drug regimen in NSCLC-affected patients will possibly complement/synergize the existing therapeutic modalities. This approach has tremendous translational significance, since it can combat drug resistance and cytotoxicity-based side effects and provides a relatively new strategy for possible application in therapy of individuals with NSCLC.

Role of forkhead box proteins in regulation of doxorubicin and paclitaxel responses in tumor cells: A comprehensive review

Chemotherapy is one of the common first-line therapeutic methods in cancer patients. Despite the significant effects in improving the quality of life and survival of patients, chemo resistance is observed in a significant part of cancer patients, which leads to tumor recurrence and metastasis. Doxorubicin (DOX) and paclitaxel (PTX) are used as the first-line drugs in a wide range of tumors; however, DOX/PTX resistance limits their use in cancer patients. Considering the DOX/PTX side effects in normal tissues, identification of DOX/PTX resistant cancer patients is required to choose the most efficient therapeutic strategy for these patients. Investigating the molecular mechanisms involved in DOX/PTX response can help to improve the prognosis in cancer patients. Several cellular processes such as drug efflux, autophagy, and DNA repair are associated with chemo resistance that can be regulated by transcription factors as the main effectors in signaling pathways. Forkhead box (FOX) family of transcription factor has a key role in regulating cellular processes such as cell differentiation, migration, apoptosis, and proliferation. FOX deregulations have been associated with resistance to chemotherapy in different cancers. Therefore, we discussed the role of FOX protein family in DOX/PTX response. It has been reported that FOX proteins are mainly involved in DOX/PTX response by regulation of drug efflux, autophagy, structural proteins, and signaling pathways such as PI3K/AKT, NF-kb, and JNK. This review is an effective step in introducing the FOX protein family as the reliable prognostic markers and therapeutic targets in cancer patients.

Circ_0079530 stimulates THBS2 to promote the malignant progression of non-small cell lung cancer by sponging miR-584-5p

BACKGROUND

Circ_0079530 has been confirmed to be a novel potential oncogene in non-small cell lung cancer (NSCLC). This study aims to explore the role and mechanism of circ_0079530 in NSCLC progression.

METHODS

Levels of circ_0079530, microRNA (miR)-584-5p, thrombospondin-2 (THBS2), PCNA, Bax, E-cadherin, and ki67 were detected by quantitative real-time PCR (qRT-PCR), western blotting and immunohistochemistry. The proliferation of NSCLC cells was measured using cell counting kit 8 (CCK8) assay, colony formation assay, and EdU staining. Cell apoptosis and motility were respectively detected by flow cytometry and transwell assays. Interaction between miR-584-5p and circ_0079530 or THBS2 was predicted by bioinformatics analysis and confirmed via luciferase reporter assay and RNA immunoprecipitation (RIP) assay. A xenograft tumor model was used to analyze the role of circ_0079530 in tumor growth in vivo.

RESULTS

Circ_0079530 was highly expressed in NSCLC tissues and cell lines. Circ_0079530 overexpression facilitated proliferation, migration, and invasion whereas it restrained the apoptosis of NSCLC cells. Circ_0079530 silence showed the opposite effects on the above malignant biological behaviors. Mechanistic analysis showed that circ_0079530 functioned as a sponge of miR-584-5p to relieve the suppressive action of miR-584-5p on its target THBS2. Additionally, circ_0079530 knockdown impeded the growth of xenografts in vivo.

CONCLUSION

Circ_0079530 promoted NSCLC progression by regulating the miR-584-5p/THBS2 axis, providing a possible circRNA-targeted therapy for NSCLC.

Downregulation of circ-YES1 suppresses NSCLC migration and proliferation through the miR-142-3p-HMGB1 axis

BACKGROUND

Circular RNAs (circRNAs) are a new family of abundant regulatory RNAs with roles in various types of cancer. While the hsa_circ_0046701 (circ-YES1) function in non-small cell lung cancer (NSCLC) is unclear.

METHODS

Circ-YES1 expression in normal pulmonary epithelial and NSCLC cells was examined. The small interfering RNA for circ-YES1 was prepared, cell proliferation and migration were assessed. Tumorigenesis in nude mice was assayed to validate the role of circ-YES1. Bioinformatics analyses and luciferase reporter assays were utilized to identify downstream targets of circ-YES1.

RESULTS

Compared to normal pulmonary epithelial cells, the circ-YES1 expression increased in NSCLC cells, and cell proliferation and migration were suppressed after circ-YES1 knockdown. Both high mobility group protein B1 (HMGB1) and miR-142-3p were found to be downstream targets of circ-YES1, and miR-142-3p inhibition and HMGB1 overexpression reversed the effects of circ-YES1 knockdown on cell proliferation and migration. Similarly, HMGB1 overexpression reversed the miR-142-3p overexpression effects on these two processes. The imaging experiment results revealed that circ-YES1 knockdown impeded tumor development and metastasis in a nude mouse xenograft model.

CONCLUSION

Taken together, our results show that circ-YES1 promotes tumor development through the miR-142-3p-HMGB1 axis and support the development of circ-YES1 probability as a new therapeutic NSCLC target.

Circular RNAs in chemotherapy resistance of lung cancer and their potential therapeutic application

Lung cancer is one of the high malignancy-related incidence and mortality worldwide, accounting for about 13% of total cancer diagnoses. Currently, the use of anti-cancer agents is still the main therapeutic method for lung cancer. However, cancer cells will gradually show resistance to these drugs with the progress of treatment. And the molecular mechanisms underlying chemotherapy agents resistance remain unclear. circRNAs are newly identified noncoding RNAs molecules with covalently closed circular structures. Previous studies have shown that circRNAs are associated with tumorigenesis and progression of various cancers, including lung cancer. Recently, growing reports have suggested that circRNAs could contribute to drug resistance of lung cancer cell through different mechanisms. Therefore, in this review, we summarized the functions and underlying mechanisms of circRNAs in regulating chemoresistance of lung cancer and discussed their potential applications for diagnosis, prognosis, and treatment of lung cancer.

Circular RNAs: pivotal role in the leukemogenesis and novel indicators for the diagnosis and prognosis of acute myeloid leukemia

Acute myeloid leukemia (AML) is an aggressive hematological malignancy and affected patients have poor overall survival (OS) rates. Circular RNAs (circRNAs) are a novel class of non-coding RNAs (ncRNAs) with a unique loop structure. In recent years, with the development of high-throughput RNA sequencing, many circRNAs have been identified exhibiting either up-regulation or down-regulation in AML patients compared with healthy controls. Recent studies have reported that circRNAs regulate leukemia cell proliferation, stemness, and apoptosis, both positively and negatively. Additionally, circRNAs could be promising biomarkers and therapeutic targets in AML. In this study, we present a comprehensive review of the regulatory roles and potentials of a number of dysregulated circRNAs in AML.

CircPIM3 regulates taxol resistance in non-small cell lung cancer via miR-338-3p/TNFAIP8 axis

Numerous work has revealed the involvement of circular RNA (circRNA) in regulating chemotherapy resistance. Here, we investigate circPIM3 role in taxol (Tax) resistance in non-small cell lung cancer (NSCLC). CircPIM3, microRNA (miR)-338-3p and tumor necrosis factor-alpha-induced protein-8 (TNFAIP8) expression were detected via quantitative real-time PCR, western blot or immunohistochemistry assay. Tax resistance was evaluated using cell counting kit-8, cell proliferation was measured by colony formation assay, cell cycle and apoptosis were examined via flow cytometry. The interplay between miR-338-3p and circPIM3 or TNFAIP8 was confirmed by dual-luciferase reporter assay. Finally, the effect of circPIM3 on Tax resistance in NSCLC in vivo was investigated by xenograft models. CircPIM3 and TNFAIP8 were upregulated in Tax-resistant NSCLC tissue and cell samples. Reducing circPIM3 expression inhibited Tax resistance, proliferation and induced cycle arrest and apoptosis in Tax-resistant NSCLC cells. Mechanically, circPIM3 absence led to downregulation of TNFAIP8 via absorbing miR-338-3p. Additionally, circPIM3 depletion increased Tax sensitivity of NSCLC in vivo. Silencing of circPIM3 suppressed Tax resistance in Tax-resistant NSCLC cells through regulation of the miR-338-3p/TNFAIP8 axis.

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

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

Hsa_circ_0092887 targeting miR-490-5p/UBE2T promotes paclitaxel resistance in non-small cell lung cancer

BACKGROUND

Chemoresistance is a major contributing factor to cancer treatment failure. Emerging research reveals that circular RNA (circRNA) dysregulation is implicated in chemoresistance. Our current study aimed to investigate the involvement of hsa_circ_0092887 in paclitaxel (PTX) resistance in non-small cell lung cancer (NSCLC).

METHODS

RT-qPCR as well as western blotting were used for the analysis of hsa_circ_0092887, miR-490-5p and UBE2T expression in PTX-resistant NSCLC tumor tissues and cells. CCK-8 assay was done to determine the IC50 value of PTX. CCK-8 assay, wound healing assay, analysis of apoptosis related proteins (Bax and Bcl-2), and xenograft mouse models were utilized to investigate the role of hsa_circ_0092887 in PTX-resistance in NSCLC. The binding sites of miR-490-5p to hsa_circ_0092887 or UBE2T were predicted by bioinformatics tools and were verified by RIP and dual-luciferase assays.

RESULTS

Expression of hsa_Circ_0092887 was upregulated in NSCLC tumor samples/cell lines, and its expression was also higher in PTX-resistant tumor samples/cell lines when compared with their respective controls. Silencing of hsa_circ_0092887 in PTX-treated NSCLC cells inhibited cell proliferation and migration, induced apoptosis, and suppressed tumor growth in xenograft mouse models in vivo. MiR-490-5p was a direct target of hsa_circ_0092887, and UBE2T was a functional downstream target of hsa_circ_0092887/miR-490-5p axis. Hsa_circ_0092887 depletion-induced anti-cancer effects in PTX-treated NSCLC cells were reversed by miR-490-5p inhibitor. Furthermore, inhibition of miR-490-5p strengthened UBE2T expression, thereby attenuating the anti-cancer effects caused by UBE2T knockdown.

CONCLUSION

Hsa_circ_0092887 depletion alleviated PTX-resistance in NSCLC cells via modulating the miR-490-5p/UBE2T axis, and the targeted management of hsa_circ_0092887-mediated signaling axis might contribute to PTX-resistance intervention in NSCLC.

Landscape of circular RNAs in different types of lung cancer and an emerging role in therapeutic resistance (Review)

Lung cancer is one of the most common malignant tumor types and the leading cause of cancer‑associated death worldwide. Different types of lung cancer exhibit differences in terms of pathophysiology and pathogenesis, and also treatment and prognosis. Accumulating evidence has indicated that circular RNAs (circRNAs) are abnormally expressed among different types of lung cancer and confer important biological functions in progression and prognosis. However, studies comparing different circRNAs in lung cancer subtypes are scarce. Furthermore, circRNAs have an important role in drug resistance and are related to clinicopathological features in lung cancer. Summaries of the association of circRNAs with drug resistance are also scarce in the literature. The present study outlined the biological functions of circRNAs and focused on discriminating differential circRNA patterns and mechanisms in three different types of lung cancer. The emerging roles of circRNAs in the resistance to chemotherapy, targeted therapy, radiotherapy and immunotherapy were also highlighted. Understanding these aspects of circRNAs sheds light on novel physiological and pathophysiological processes of lung cancer and suggests the application of circRNAs as biomarkers for diagnosis and prognosis, as well as therapeutic resistance.

CircPTK2 promotes cell viability, cell cycle process, and glycolysis and inhibits cell apoptosis in acute myeloid leukemia by regulating miR-582-3p/ALG3 axis

BACKGROUND

Circular RNA (circRNA) regulates the pathogenesis of acute myeloid leukemia (AML). However, the mechanism of circRNA protein tyrosine kinase 2 (circPTK2) in AML remains unclear.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) assay was adopted for circPTK2, miR-582-3p and alpha-1,3-mannosyltransferase (ALG3) mRNA levels. 3-(4, 5-Dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) assay, and 5'-ethynyl-2'-deoxyuridine (EdU) assay were conducted for cell proliferation. Flow cytometry analysis was employed for cell apoptosis and cell cycle process. The glycolysis level was estimated by specific commercial kits. Western blot assay was utilized for protein levels. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were performed to verify the interaction between miR-582-3p and circPTK2 or ALG3.

RESULTS

CircPTK2 level was enhanced in AML peripheral blood samples and cells. CircPTK2 knockdown restrained AML cell proliferation and glycolysis and promoted cell apoptosis and cell cycle arrest. Mechanically, circPTK2 functioned as the sponge for miR-582-3p to positively ALG3 expression in AML cells. Moreover, miR-582-3p inhibition ameliorated the impacts of circPTK2 knockdown on AML cell processes. MiR-582-3p overexpression regulated cell phenotypes by targeting ALG3.

CONCLUSION

CircPTK2 contributed to AML cell malignant behaviors by modulation of miR-582-3p/ALG3 axis, which might provide a potential target for AML therapy.

The function and clinical implication of circular RNAs in lung cancer

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

The emerging role of circular RNAs in drug resistance of non-small cell lung cancer

Due to the characteristics of aggressiveness and high risk of postoperative recurrence, non-small cell lung cancer (NSCLC) is a serious hazard to human health, accounting for 85% of all lung cancer cases. Drug therapies, including chemotherapy, targeted therapy and immunotherapy, are effective treatments for NSCLC in clinics. However, most patients ultimately develop drug resistance, which is also the leading cause of treatment failure in cancer. To date, the mechanisms of drug resistance have yet to be fully elucidated, thus original strategies are developed to overcome this issue. Emerging studies have illustrated that circular RNAs (circRNAs) participate in the generation of therapeutic resistance in NSCLC. CircRNAs mediate the modulations of immune cells, cytokines, autophagy, ferroptosis and metabolism in the tumor microenvironment (TME), which play essential roles in the generation of drug resistance of NSCLC. More importantly, circRNAs function as miRNAs sponges to affect specific signaling pathways, directly leading to the generation of drug resistance. Consequently, this review highlights the mechanisms underlying the relationship between circRNAs and drug resistance in NSCLC. Additionally, several therapeutic drugs associated with circRNAs are summarized, aiming to provide references for circRNAs serving as potential therapeutic targets in overcoming drug resistance in NSCLC.

Circ_0000808 promotes the development of non-small cell lung cancer by regulating glutamine metabolism via the miR-1827/SLC1A5 axis

Background

Circular RNA (circRNA) has been proved to be an important molecular target for cancer treatment. However, the function and molecular mechanism of circ_0000808 in non-small cell lung cancer (NSCLC) are still unclear.

Methods

Quantitative real-time PCR was used to detect the expression of circ_0000808, miR-1827, and solute carrier family 1 member 5 (SLC1A5). Cell proliferation, apoptosis, migration, and invasion were measured by cell counting kit 8 assay, colony formation assay, EdU staining, flow cytometry, wound healing assay, and transwell assay. The protein expression was measured by Western blot analysis. Dual-luciferase reporter assay and RIP assay were used to investigate the interactions between miR-1827 and circ_0000808 or SLC1A5. Cell glutamine metabolism was assessed by determining glutamine uptake, glutamate production, and α-ketoglutarate production. Xenograft mouse model was used to assess the in vivo effects of circ_0000808.

Results

Circ_0000808 expression was upregulated in NSCLC tissues and cancer cells, and its silencing inhibited NSCLC cell proliferation, migration, and invasion and led to apoptosis. Further results confirmed that circ_0000808 interacted with miR-1827 to positively regulate SLC1A5. The rescue experiments showed that miR-1827 inhibitor reversed the suppressive effect of circ_0000808 knockdown on the malignant behaviors of NSCLC cells. Also, SLC1A5 overexpression abolished the inhibition effect of miR-1827 on NSCLC cell progression. In addition, circ_0000808/miR-1827/SLC1A5 axis positively regulated the glutamine metabolism process in NSCLC cells. Moreover, circ_0000808 knockdown reduced the NSCLC tumor growth in vivo.

Conclusion

In summary, our data showed that circ_0000808 enhanced the progression of NSCLC by promoting glutamine metabolism through the miR-1827/SLC1A5 axis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-022-02777-x.

Silencing circFTO inhibits malignant phenotype through modulating DUSP4 expression in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most diagnosed malignancy in kidney. Studies on the role of circular RNAs in kidney cancer are increasing. In this study, we employed high throughput sequencing and tissue micro array to detect and verify one of the key circular RNAs, circFTO, in ccRCC. The effect of circFTO on the proliferation and invasiveness of ccRCC cells and the corresponding mechanism were studied both in vitro and in vivo via multiple methods. We confirmed that circFTO was up regulated in ccRCC and correlated with a more aggressive phenotype. The up regulated circFTO could sponge and block the function of miR-514b-3p, a reported tumor suppressor, and caused overexpression of DUSP4. DUSP4 was found to lead to KRAS/ERK pathway activation, increased epithelial-mesenchymal transition (EMT) and inhibition of autophagy in ccRCC cells, which in the end boosted the proliferation and invasiveness of ccRCC. We thus concluded that circFTO/miR-514b-3p/DUSP4 axis may play an important role in ccRCC development and could be a potential biomarker and therapeutic target.

Role of circular RNAs in the diagnosis, regulation of drug resistance and prognosis of lung cancer (Review)

Lung cancer is one of the most common malignant tumors in China and is the highest cause of mortality among male and female patients, both in urban and rural areas. A subset of patients with lung cancer only display chest tightness without any other obvious symptoms. This is because most symptoms do not manifest during the early stages of disease development. Consequently, most patients with lung cancer are diagnosed when the disease is in the advanced stages, when they are already unfit for surgical treatment. Furthermore, the prognosis of patients with lung cancer is poor. The 5-year survival rate of patients with stage IA lung cancer is 85%, compared with 6% in those with stage IV. This requires the development of strategies for early diagnosis, treatment and prognosis to improve the management of lung cancer. Circular RNAs (circRNAs) belong to a class of closed circular non-coding RNAs formed by reverse splicing of a precursor mRNA. These RNAs are highly stable, ubiquitously expressed, conserved, and show high specificity. CircRNAs regulate biological processes, such as the proliferation, differentiation and invasion of lung cancer cells. Therefore, they can be used as biomarkers for the early diagnosis and prognosis prediction of lung cancer, as well as novel targets for therapy design. In the present review, the biological characteristics and functions of circRNAs, as well as their application in the diagnosis, control of drug resistance and effect on the prognosis of patients with lung cancer, will be discussed.

CircRNAs in lung cancer- role and clinical application

Lung cancer holds the highest mortality rate among malignancies worldwide. Nevertheless, the potential molecular mechanisms of its tumorigenesis and evolution remain obscure. Circular RNAs (circRNAs), a broad category of covalently closed molecules, follow a malignancy-restricted expression pattern. Leading-edge studies have demonstrated the clinical application prospects of circRNAs in lung cancer. Herein, this review elucidates the biogenesis, biological functions, and pathophysiology of circRNAs. Furthermore, we underscore the forefront of the diagnostic, prognostic, and therapeutic potential of circRNAs in lung cancer as well as discuss the bottleneck that needs to be overcome to translate the basic advances of circRNAs into clinical practice.

Circular RNA EPB41 expression predicts unfavorable prognoses in NSCLC by regulating miR-486-3p/eIF5A axis-mediated stemness

Dysregulation of circular RNAs (circRNAs) has recently been found to play an important role in the progression and development of cancers such as non-small cell lung cancer (NSCLC). Yet the functions of many circRNAs in NSCLC remain unclear. In this study, the circRNA expression profiles in NSCLC tumor tissues and adjacent non-tumorous tissues were detected by high-throughput sequencing. Bioinformatics analyses, the dual-luciferase reporter system, fluorescence in situ hybridization (FISH) and miRNA/mRNA high-throughput sequencing were used to identify circ-EPB41 and its downstream target. The subcutaneous tumor/caudal vein transfer mouse model was used for tumor growth and invasion analysis. The results show that the circ-EPB41 was upregulated in NSCLC tissues and cell lines. Increased circ-EPB41 expression in NSCLC was significantly correlated with malignant characteristics, and positive to post-surgical overall survival of NSCLC patients. Reduced circ-EPB41 expression in NSCLC decreased cell proliferation and invasion in both in vitro and in vivo experiments. The miRNA/mRNA high-throughput sequencing suggested that downregulation of circ-EPB41 promoted microRNA (miR)-486-3p and suppressed eukaryotic translation initiation factor 5A (eIF5A) expression. Luciferase reporter experiments confirmed that miR-486-3p/eIF5A were downstream targets of circ-EPB41. In addition, we also found that downregulation of circ-EPB41 suppressed self-renewal and decreased expression of stemness markers SOX2, OCT-4, Nanog and CD133 by sponging miR-486-3p to enhance eIF5A expression. Taken togeter, these data revealed the important role of circ-EPB41 in regulating NSCLC cell invasion and proliferation by modifying miR-486-3p/eIF5A axis-mediated stemness. We believe our study provides a novel perspective regarding the role of circRNAs in NSCLC progression.

CircNRIP1 acts as a sponge of miR-1200 to suppress osteosarcoma progression via upregulation of MIA2

Circular RNAs (circRNAs), a class of non-coding RNAs, play an essential role in embryo development and carcinogenesis, circNRIP1 was recently identified to promote development of multiple human cancers. This study investigated the role of circNRIP1 in osteosarcoma (OS) cells and the potential mechanisms relating to the sponging miRNAs and their target genes. OS cell lines and normal human osteoblasts were grown for qRT-PCR analysis of circNRIP1 expression and functions of circNRIP1 expression in OS cell proliferation, migration, and invasion in vitro. Bioinformatics analysis was then performed to predict the sponge miRNA of circNRIP1 and the target gene, which was confirmed by using the dual-luciferase reporter assay. The in vivo functions of circNRIP1 was evaluated in OS cell xenograft models, while levels of relevant marker genes were examined using immunohistochemistry. CircNRIP1 was mainly localized in OS cell cytoplasm and significantly lower in OS cell lines than in normal human osteoblasts. CircNRIP1 overexpression significantly inhibited OS cell proliferation, migration, and invasion in vitro. miR-1200 was predicted as the sponge miRNA of circNRIP1 and directly interacted with circNRIP1 confirmed by the dual-luciferase reporter assay. Moreover, miR-1200 overexpression significantly alleviated the inhibitory effect of circNRIP1 on OS cells. A protein-coding gene MIA2 was identified as the miR-1200 targeting gene and reversely associated with miR-1200 expression in OS cells. Increase in MIA2 expression in a murine OS cell xenograft model was associated with circNRIP1 expression in inhibition of OS cell xenograft growth in vivo. These data support the circNRIP1 OS-suppressive role by sponge of miR-1200 expression and in turn to upregulate MIA2 expression.

Discovery of Small Molecules Simultaneously Targeting NAD(P)H:Quinone Oxidoreductase 1 and Nicotinamide Phosphoribosyltransferase: Treatment of Drug-Resistant Non-small-Cell Lung Cancer

Targeting NAD⁺ metabolism has emerged as an effective anticancer strategy. Inspired by the synergistic antitumor effect between NAD(P)H:quinone oxidoreductase 1 (NQO1) substrates increasing the NAD consumption and nicotinamide phosphoribosyltransferase (NAMPT) inhibitors hampering the NAD synthesis, first-in-class small molecules simultaneously targeting NQO1 and NAMPT were identified through structure-based design. In particular, compound 10d is an excellent NQO1 substrate that is processed faster than TSA by NQO1 and exhibited a slightly decreased NAMPT inhibitory potency than that of FK866. It can selectively inhibit the proliferation of NQO1-overexpressing A549 cells and taxol-resistant A549/taxol cells and also induce cell apoptosis and inhibit cell migration in an NQO1- and NAMPT-dependent manner in A549/taxol cells. Significantly, compound 10d demonstrated excellent in vivo antitumor efficacy in the A549/taxol xenograft models with no significant toxicity. This proof-of-concept study affirms the feasibility of discovering small molecules that target NQO1 and NAMPT simultaneously, and it also provides a novel, effective, and selective anticancer strategy.

Advances in the Study of CircRNAs in Tumor Drug Resistance

Recent studies have revealed that circRNAs can affect tumor DNA damage and repair, apoptosis, proliferation, and invasion and influence the transport of intratumor substances by acting as miRNA sponges and transcriptional regulators and binding to proteins in a variety of ways. However, research on the role of circRNAs in cancer radiotherapy and chemoresistance is still in its early stages. Chemotherapy is a common approach to oncology treatment, but the development of tumor resistance limits the overall clinical efficacy of chemotherapy for cancer patients. The current study suggests that circRNAs have a facilitative or inhibitory effect on the development of resistance to conventional chemotherapy in a variety of tumors, suggesting that circRNAs may serve as a new direction for the study of antitumor drug resistance. In this review, we will briefly discuss the biological features of circRNAs and summarize the recent progression of the involvement of circRNAs in the development and pathogenesis of cancer chemoresistance.

Circ_0030998 Restrains Cisplatin Resistance Through Mediating miR-1323/PDCD4 Axis in Non-small Cell Lung Cancer

We aimed to explore the underlying mechanism behind the cisplatin (DDP) resistance of non-small cell lung cancer (NSCLC) cells to identify novel potential therapeutic targets to overcome chemoresistance. Real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot assay were applied to analyze RNA and protein expression, respectively. Cell Counting Kit-8 (CCK8) assay was conducted to analyze the DDP resistance of NSCLC cells. Colony formation assay and 5-Ethynyl-2'-deoxyuridine (EdU) assay were performed to analyze cell proliferation ability. Flow cytometry was applied to assess cell apoptosis. Cell migration and invasion were assessed by transwell assays. Cell glycolytic metabolism was analyzed using commercial kits. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were performed to test the intermolecular target relations. Circular RNA_0030998 (circ_0030998) was down-regulated in DDP-resistant NSCLC tissues and cell lines. Circ_0030998 overexpression restrained the DDP resistance, proliferation, migration, invasion and glycolytic metabolism and triggered the apoptosis of NSCLC cells. Circ_0030998 overexpression contributed to the anti-tumor effect of DDP in the growth of xenograft tumor in vivo. MicroRNA-1323 (miR-1323) was a molecular target of circ_0030998 in NSCLC cells. Circ_0030998 overexpression-mediated effects on the DDP resistance and malignant properties of NSCLC cells were largely based on its negative regulation of miR-1323. MiR-1323 interacted with programmed cell death 4 (PDCD4). Circ_0030998 positively regulated PDCD4 expression partly through sponging miR-1323. MiR-1323 silencing restrained DDP resistance and progression of NSCLC partly through up-regulating PDCD4. Circ_0030998 suppressed DDP resistance and NSCLC progression depending on the regulation of miR-1323/PDCD4 axis.

CircMYC promotes proliferation, migration, invasion and inhibits apoptosis of small cell lung cancer by targeting miR-145/ Matrix Metallopeptidase 2 axis

Circular RNAs (circRNAs) are involved in the carcinogenesis of lung cancer. Human MYC gene is highly expressed in melanoma, multiple myeloma, and nasopharyngeal carcinoma. We aimed to investigate the role of circMYC in small cell lung cancer (SCLC). The expression of cirMYC in SCLC tissues and cells were examined. Functional studies were performed to evaluate the roles of circMYC in SCLC cells. Luciferase reporter gene assay, RNA pull-down assay, and rescue experiments were performed to evaluate the regulatory relationship between circMYC and miR-145, and MiR-145 and MMP2 mRNA. We found that CirMYC was highly expressed in SCLC tissues and cells. Knockdown of circMYC could inhibit cell proliferation, migration, invasion, and induce apoptosis. CircMYC targeted miR-145 and miR-145 targeted MMP2 (Matrix Metallopeptidase 2) mRNA. Our data indicated that circMYC upregulates the expression of MMP-2 by inhibiting miR-145, which functions to promote the proliferation, migration, and invasion and inhibit the apoptosis of SCLC. These findings suggest that targeting circMYC/miR-145/MMP-2 could serve as a potential therapeutic strategy for SCLC treatment.

Circ_0011292 knockdown mitigates progression and drug resistance in PTX-resistant non-small-cell lung cancer cells by regulating miR-433-3p/CHEK1 axis

BACKGROUND

Non-small-cell lung cancer (NSCLC) is one of the most common malignant tumors on earth. Circular RNAs have been disclosed to be vital regulators in the chemoresistance and development of diverse cancers, including NSCLC. Here, we attempted to explore the function of circ_0011292 in paclitaxel (PTX)-resistant NSCLC cells.

METHODS

Quantitative real-time polymerase chain reaction or western blot was performed to detect the expression of circ_0011292, microRNA-433-3p (miR-433-3p), and checkpoint kinase 1 (CHEK1). Ribonuclease R (RNase R) assay was performed to assess the stability of circ_0011292. Cell Counting Kit-8 assay was conducted to evaluate the half maximal inhibitory concentration of PTX and cell viability. Cell proliferation was monitored by Edu incorporation and colony formation assays. Cell cycle and apoptosis were detected by flow cytometry. Transwell assay was implemented to assess cell migration and invasion. Western blot assay was utilized to determine the protein levels. Dual-luciferase reporter assay was carried out to verify the targeted interaction between miR-433-3p and circ_0011292 or CHEK1. Xenograft tumor model was constructed for determining the effect of circ_0011292 in NSCLC growth in vivo.

RESULTS

Circ_0011292 was upregulated in PTX-resistant NSCLC tissues and cells. Circ_0011292 or CHEK1 knockdown enhanced PTX sensitivity and cell apoptosis, and repressed cell proliferation, migration, and invasion in PTX-resistant NSCLC cells. Mechanistically, circ_0011292 was a sponge of miR-433-3p and miR-433-3p directly targeted CHEK1. Meanwhile, silencing miR-433-3p or overexpressing CHEK1 respectively abrogated the impacts of circ_0011292 deletion or miR-433-3p introduction on PTX resistance and cell progression in PTX-resistant NSCLC cells in vitro. Moreover, circ_0011292 could positively modulate CHEK1 expression through sponging miR-433-3p. In addition, circ_0011292 knockdown retarded tumor growth of NSCLC in vivo.

CONCLUSION

Circ_0011292 could accelerate PTX resistance and cell malignant progression of NSCLC cells partially through the regulation of circ_0011292/miR-433-3p/CHEK1 axis.

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.

Circ_0011292 Enhances Paclitaxel Resistance in Non-Small Cell Lung Cancer by Regulating miR-379-5p/TRIM65 Axis

Background: Non-small cell lung cancer (NSCLC) is the most prevalent cancer in the world. Chemotherapy resistance is a major obstacle to NSCLC therapy. This study explored the role and molecular mechanism of circular RNA 0011292 (circ_0011292) in tumorigenesis and chemoresistance of NSCLC. Methods: The levels of circ_0011292, miR-379-5p, and tripartite motif-containing protein 65 (TRIM65) were measured by quantitative real-time polymerase chain reaction or Western blot assay. Cell proliferation was assessed by Cell Counting Kit-8 (CCK-8) assay. Cell apoptosis was monitored by flow cytometry. Cell migration and invasion were detected by transwell assay. The levels of apoptosis-related and epithelial-mesenchymal transition-related proteins were examined by Western blot. The half-inhibition concentration (IC50) of paclitaxel (PTX) was evaluated by CCK-8 assay. Xenograft model was established to analyze the effect of circ_0011292 on PTX resistance of NSCLC in vivo. The interaction among circ_0011292, miR-379-5p, and TRIM65 was verified by dual-luciferase reporter assay and RNA immunoprecipitation assay. Results: Circ_0011292 and TRIM65 were upregulated, while miR-379-5p was downregulated in NSCLC tissues and cells. Circ_0011292 knockdown hindered NSCLC progression and enhanced PTX sensitivity of NSCLC. Circ_0011292 silencing reduced PTX resistance in vivo. Besides, miR-379-5p potentiated PTX sensitivity by targeting TRIM65. Also, circ_0011292 increased PTX resistance by sponging miR-379-5p. Conclusion: Circ_0011292 facilitated tumorigenesis and PTX resistance in NSCLC by regulating the miR-379-5p/TRIM65 axis, suggesting that circ_0011292 was a promising therapeutic target for NSCLC chemotherapy.

Circ_0020123 enhances the cisplatin resistance in non-small cell lung cancer cells partly by sponging miR-140-3p to regulate homeobox B5 (HOXB5)

Cisplatin (DDP) therapy is widely used for the treatment of non-small cell lung cancer (NSCLC), but the curative effect is limited by chemoresistance. This study was designed to explore circ_0020123 function in DDP resistance of NSCLCDDP. Expression detection for circ_0020123, microRNA-140-3p (miR-140-3p) and homeobox B5 (HOXB5) was performed by real-time polymerase chain reaction (qRT-PCR). Half inhibitory concentration (IC50) of DDP and cell proliferation was detected by Cell Counting Kit-8 (CCK-8) assay. Colony formation ability was assessed using colony formation assay. Cell migration and invasion were evaluated via transwell assay. Cell apoptosis was examined by flow cytometry. Protein analysis was conducted by Western blot. Dual-luciferase reporter assay was used to affirm target interaction. Circ_0020123 expression was upregulated in DDP-resistant NSCLC cells. DDP resistance was reduced by downregulation of circ_0020123 in NSCLC cells. Circ_0020123 was identified as a miR-140-3p sponge. The effect of si-circ_0020123 on DDP resistance was partly associated with miR-140-3p upregulation. HOXB5 was a downstream target for miR-140-3p. Overexpression of HOXB5 mitigated miR-140-3p-induced inhibition of DDP resistance in NSCLC cells. Circ_0020123 upregulated the level of HOXB5 partly via sponging miR-140-3p. Also, circ_0020123 promoted tumor growth in NSCLC/DDP xenografts by regulating miR-140-3p and HOXB5 levels at least in part. These results revealed that circ_0020123 promoted DDP resistance in NSCLC cells partly by targeting miR-140-3p/HOXB5 axis, indicating that circ_0020123 might be used as a molecular target in DDP treatment for NSCLC.

CircRNA PRH1-PRR4 stimulates RAB3D to regulate the malignant progression of NSCLC by sponging miR-877-5p

BACKGROUND

Previous reports have confirmed the importance of circular RNA (circRNA) in the malignant progression of non-small-cell lung cancer (NSCLC). However, the role of circRNA PRH1-PRR4 readthrough (circPRH1-PRR4) in NSCLC progression was unclear. This study was designed to reveal the mechanism behind circPRH1-PRR4 regulating NSCLC progression.

METHODS

Quantitative real-time polymerase chain reaction and western blot were employed to detect the expression of circPRH1-PRR4, microRNA-877-5p (miR-877-5p), the member RAS oncogene family (RAB3D), and other indicated protein markers. The positive expression rate of RAB3D was detected by immunohistochemistry assay. Cell proliferation was investigated by cell colony formation and 5-ethynyl-2'-deoxyuridine assays. Flow cytometry was employed to quantify apoptotic cells. Wound-healing and transwell invasion assays were used to evaluate cell metastasis. The interaction among circPRH1-PRR4, miR-877-5p, and RAB3D was identified by dual-luciferase reporter assay. In vivo assay was implemented to demonstrate the effect of circPRH1-PRR4 on tumor formation.

RESULTS

As compared with controls, NSCLC tissues and cells displayed high expression of circPRH1-PRR4 and RAB3D, and low expression of miR-877-5p. Reduced expression of circPRH1-PRR4 resulted in inhibition of cell proliferation, migration, and invasion, but promotion of cell apoptosis in vitro. In support, circPRH1-PRR4 silencing inhibited tumor formation in vivo. Knockdown of miR-877-5p, a target miRNA of circPRH1-PRR4, relieved circPRH1-PRR4 absence-mediated action. Additionally, RAB3D was identified as a target mRNA of miR-877-5p. Importantly, circPRH1-PRR4 regulated RAB3D expression by miR-877-5p.

CONCLUSION

CircPRH1-PRR4 knockdown impeded NSCLC cell malignancy by the miR-877-5p/RAB3D pathway, providing a possible circRNA-targeted therapy for NSCLC.

CircFBXW8 Acts an Oncogenic Role in the Malignant Progression of Non-small Cell Lung Carcinoma by miR-370-3p-Dependent Regulation of TRIM44

Non-small cell lung carcinoma (NSCLC) is an aggressive malignant tumor. Growing evidences have revealed that circular RNA (circRNA) is involved in NSCLC progression. This study aims to investigate the role of circular RNA F-box and WD repeat domain containing 8 (circFBXW8) in NSCLC progression and the underlying mechanism. The expression of circFBXW8, microRNA-370-3p (miR-370-3p) and tripartite motif containing 44 (TRIM44) mRNA was detected by quantitative real-time polymerase chain reaction (qRT-PCR). Protein expression was detected by western blot analysis or immunohistochemistry assay. Additionally, cell viability, colony-forming ability, proliferation and apoptosis were investigated by 3-(4,5-Dimethylthazol-2-yl)-2,5-diphenyltetrazolium bromide, cell colony formation, 5-Ethynyl-29-deoxyuridine and flow cytometry analysis assays, respectively. Cell migratory and invasive abilities were examined by wound-healing and transwell assays. The regulatory relationship between miR-370-3p and circFBXW8 or TRIM44 was identified by dual-luciferase reporter and RNA pull-down assays. Furthermore, xenograft experiment was employed to explain the effect of circFBXW8 silencing on tumor formation. CircFBXW8 and TRIM44 expression were upregulated, while miR-370-3p was downregulated in NSCLC tissues, cells and the exosomes from NSCLC cells compared with respective controls. CircFBXW8 depletion repressed NSCLC cell proliferation, migration and invasion, but promoted cell apoptosis. CircFBXW8 acted as a sponge of miR-370-3p and regulated NSCLC cell malignancy by binding to miR-370-3p. Additionally, miR-370-3p repressed NSCLC cell processes by regulating TRIM44. CircFBXW8 knockdown inhibited tumor formation in vivo. Further, circFBXW8 secretion was mediated by exosomes. CircFBXW8 modulated NSCLC progression by increasing TRIM44 expression through sponging miR-370-3p, which provided a new direction for studying the therapy of NSCLC.

The Role of Circular RNAs in the Drug Resistance of Cancers

Cancer is a major threat to human health and longevity. Chemotherapy is an effective approach to inhibit cancer cell proliferation, but a growing number of cancer patients are prone to develop resistance to various chemotherapeutics, including platinum, paclitaxel, adriamycin, and 5-fluorouracil, among others. Significant progress has been made in the research and development of chemotherapeutic drugs over the last few decades, including targeted therapy drugs and immune checkpoint inhibitors; however, drug resistance still severely limits the application and efficacy of these drugs in cancer treatment. Recently, emerging studies have emphasized the role of circular RNAs (circRNAs) in the proliferation, migration, invasion, and especially chemoresistance of cancer cells by regulating the expression of related miRNAs and targeted genes. In this review, we comprehensively summarized the potential roles and mechanisms of circRNAs in cancer drug resistance including the efflux of drugs, apoptosis, intervention with the TME (tumor microenvironment), autophagy, and dysfunction of DNA damage repair, among others. Furthermore, we highlighted the potential value of circRNAs as new therapeutic targets and prognostic biomarkers for cancer.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Circ_SETD3 regulates gefitinib sensitivity and tumor progression by miR-873-5p-dependent regulation of APPBP2 in non-small cell lung cancer

Previous data have shown the prominent clinical efficacy of gefitinib in non-small cell lung cancer (NSCLC) patients. However, its therapeutic efficacy is limited because of the development of gefitinib resistance. This research is designed to investigate the role of circRNA SET domain containing 3, actin histidine (circ_SETD3) in the sensitivity of NSCLC to gefitinib. The expression of circ_SETD3, microRNA-873-5p (miR-873-5p) and amyloid protein-binding protein 2 (APPBP2) was detected by qRT-PCR. Protein expression was determined by western blot analysis or immunohistochemistry assay. The half-maximal inhibitory concentration of gefitinib was determined by 3-(4,5-Dimethylthazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell proliferation was investigated by 5-Ethynyl-29-deoxyuridine (EdU), cell colony formation and MTT assays. Cell apoptosis was analyzed by Annexin V-fluorescein isothiocyanate and propidium iodide double staining assay. Transwell assay was employed to evaluate cell migration and invasion. Additionally, the binding relationship between miR-873-5p and circ_SETD3 or APPBP2 was predicted by starbase online database, and identified by a dual-luciferase reporter assay. Further, circ_SETD3 silencing-mediated effect on tumor sensitivity to gefitinib in vivo was confirmed by xenograft mouse model experiment. Circ_SETD3 and APPBP2 expression were upregulated, while miR-873-5p was downregulated in gefitinib-resistant NSCLC tissues and cells compared with gefitinib-sensitive NSCLC tissues or cells. Reduced expression of circ_SETD3 repressed gefitinib resistance, proliferation, migration and invasion, but induced apoptosis of gefitinib-resistant NSCLC cells. Additionally, circ_SETD3 modulated gefitinib sensitivity and tumor development by binding to miR-873-5p. APPBP2 upregulation attenuated miR-873-5p-mediated gefitinib sensitivity and NSCLC progression. Furthermore, circ_SETD3 absence improved tumor sensitivity to gefitinib in vivo. Circ_SETD3 knockdown improved gefitinib sensitivity and repressed NSCLC cell malignancy via miR-873-5p/APPBP2 axis, which provides a theoretical basis for using circ_SETD3-based therapeutic strategies to improve NSCLC sensitivity to gefitinib.

Circular RNA hsa_circ_0002360 promotes non-small cell lung cancer progression through upregulating matrix metalloproteinase 16 and sponging multiple micorRNAs

Dysregulated circular RNAs (circRNAs) are involved in the progression of non-small cell lung cancer (NSCLC). However, the role of has_circ_0002360 (circ_0002360) in NSCLC has rarely been reported. In this study, circ_0002360 expression in NSCLC tissues and cell lines was measured using microarray data and quantitative real-time PCR (qRT-PCR). After gain-of-function and loss-of-function, cell models were established; 5-bromo-2-deoxyuridine (BrdU) and transwell assays were conducted to detect NSCLC cell growth, migration, and invasion. What is more, bioinformatic analysis and dual-luciferase reporter assay were adopted to show how circ_0002360, microRNAs (miR-127-5p, miR-145-5p, miR-585-3p, and miR-758-3p), and matrix metalloproteinase 16 (MMP16) 3ʹUTR interact with each other. Western blotting was executed to probe the regulatory effects of circ_0002360 and these miRNAs on MMP16 protein expression in NSCLC cells. We found that circ_0002360 expression was raised in NSCLC tissues. High circ_0002360 expression predicted a short overall survival time for NSCLC patients. Circ_0002360 overexpression promoted NSCLC cell proliferative, migrative, and invasive abilities, and circ_0002360 depletion worked oppositely. MiR-127-5p, miR-145-5p, miR-585-3p, and miR-758-3p were the targets of circ_0002360, and circ_0002360 could regulate MMP16 expression by competitively binding with the above miRNAs. In summary, circ_0002360 serves as a competitive endogenous RNA to raise MMP16 expressions by competitively binding to miR-127-5p, miR-145-5p, miR-585-3p, and miR-758-3p, thereby promoting NSCLC progression.

circ_0002346 Suppresses Non-Small-Cell Lung Cancer Progression Depending on the Regulation of the miR-582-3p/STXBP6 Axis

Background

Accumulating articles have reported the pivotal regulatory roles of circular RNAs (circRNAs) in non-small-cell lung cancer (NSCLC) tumorigenesis. Here, our purpose was to explore the role of circ_0002346 in NSCLC progression and its associated mechanism.

Methods

Cell proliferation ability was assessed by a 5-ethynyl-2′-deoxyuridine (EDU) assay and a colony formation assay. Transwell assays were conducted to analyze cell migration and invasion abilities. Cell apoptosis was analyzed by flow cytometry and by using a caspase3 activity assay kit. The glycolysis of NSCLC cells was analyzed using a fluorescence-based glucose/lactate assay kit. A dual-luciferase reporter assay and an RNA pull-down assay were performed to verify the binding relationship between microRNA-582-3p (miR-582-3p) and circ_0002346 or syntaxin-binding protein 6 (STXBP6).

Results

circ_0002346 level was prominently downregulated in NSCLC tissues and cell lines. circ_0002346 overexpression significantly suppressed the proliferation, migration, invasion, and glycolysis and triggered the apoptosis of NSCLC cells. circ_0002346 directly interacted with miR-582-3p, and circ_0002346 overexpression-mediated antitumor effects in NSCLC cells were partly reversed by miR-582-3p overexpression. miR-582-3p directly interacted with the 3′ untranslated region (3′UTR) of STXBP6, and STXBP6 silencing partly counteracted circ_0002346 overexpression-mediated antitumor influences in NSCLC cells. circ_0002346 can upregulate the expression of STXBP6 by acting as a miR-582-3p sponge in NSCLC cells. circ_0002346 overexpression suppressed xenograft tumor growth in vivo.

Conclusion

circ_0002346 overexpression suppressed the malignant properties of NSCLC cells by binding to miR-582-3p to induce the expression of STXBP6.

Circular RNA_0001073 (circ_0001073) Suppresses The Progression of Non-Small Cell Lung Cancer via miR-582-3p/RGMB Axis

OBJECTIVE

Reportedly, circular RNAs (circRNAs) exert a crucial regulatory role in cancer. Circ_0001073 is derived from exons 3-5 of ACVR2A gene, which inhibits cancer progression. However, the role and mechanism of circ_0001073 in non-small cell lung cancer (NSCLC) are unclear. This study aimed to explore the role and mechanism of circ_0001073 in the development of NSCLC.

MATERIALS AND METHODS

In this experimental study, microarray analysis was employed to filter differential expressed circRNAs in NSCLC tissues. Also, circ_0001073, microRNA-582-3p (miR-582-3p), and repulsive guidance molecule B (RGMB) mRNA expressions were examined by quantitative real-time polymerase chain reaction (qRT-PCR). NSCLC cell multiplication was measured by the cell counting kit-8 (CCK-8) assay. Scratch healing experiment and Transwell experiment were performed to assess cell migration and invasion, respectively. Flow cytometry was applied to analyze the apoptosis of NSCLC cells. Western blot was employed to assess RGMB protein expression. Additionally, dualluciferase reporter gene experiment and RNA immunoprecipitation (RIP) experiment were applied to probe the binding sites between miR-582-3p and circ_0001073 or RGMB.

RESULTS

circ_0001073 was remarkably under-expressed in NSCLC tissues and cells. circ_0001073 overexpression impeded the multiplication, migration, and invasion and enhanced the apoptosis of NSCLC cells in vitro. circ_0001073 directly bound to miR-582-3p and acted as a miRNA sponge to regulate RGMB expression. Besides, miR-582-3p overexpression or knockdown of RGMB remarkably reversed the malignant phenotypes of NSCLC cells induced by the up-regulation of circ_0001073 expression.

CONCLUSION

Circ_0001073 up-regulates RGMB expression through adsorbing miR-582-3p to inhibit NSCLC progression, suggesting its potential as a novel therapeutic target in NSCLC.

Regulatory roles of phytochemicals on circular RNAs in cancer and other chronic diseases

As novel non-coding RNAs (ncRNAs), circular RNAs (circRNAs) play an essential role in the pathogenesis of many chronic diseases, and the regulation of these functional molecules has become a research hotspot gradually. Within the past decade, phytochemicals were reported to regulate the expression of long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) in various chronic diseases, and more recently, most studies focus on the regulatory roles of phytochemicals on circRNAs. Abnormal expression of circRNAs has been identified in chronic diseases like cancer, heart failure, depression and atherosclerosis, and numerous studies have revealed the modulation of circRNAs by phytochemicals including berberine, celastrol, cinnamaldehyde, curcumin, et al. The expression of circRNAs, such as circSATB2 and circFOXM1, were modulated by phytochemicals, and these regulations further affected cell proliferation, apoptosis, migration, invasion, autophagy, chemosensitivity, radiosensitivity and other biological processes. Mechanismly, the circRNAs mainly functioned as miRNA sponge, subsequently affecting miRNA-mediated regulation of target genes and related cell signaling pathways. In this review, we summarized the impact of phytochemicals on circRNAs expression and biological function, and discussed the mechanisms underlying phytochemicals regulating circRNAs in cancer and other chronic diseases.

LINC00511 Knockdown Suppresses Resistance to Cisplatin in Lung Adenocarcinoma by Interacting with miR-182-3p and BIRC5

We studied the role of long intergenic non-protein coding RNA 00,511 (LINC00511) in lung adenocarcinoma (LUAD), with a specific focus on acquired chemoresistance. LINC00511 expression was higher in responders to cisplatin (DDP, another name for cisplantin) than non-responders, in A549/DDP cells than in parental A549 cells and normal human bronchial epithelial cells (16HBE). LINC00511 knockdown decreased the half maximal inhibitory concentration (IC50) value, suppressed A549/DDP cell viability, but induced apoptosis. LINC00511 bound with miR-182 and increased the expression of baculoviral inhibitor of apoptosis protein (IAP) repeat containing 5 (BIRC5). BIRC5 knockdown mimicked the effects of LINC00511 knockdown on the IC50 value, A549/DDP cell viability, and apoptosis. BIRC5 overexpression negated the effects of LINC00511 knockdown on A549/DDP cells. In vivo, LINC00511 knockdown attenuated the tumorigenesis of A549/DDP cells after DDP injection. These results provide a novel LINC00511/miR-182/BIRC5 paradigm to explain the mechanism of acquired DDP resistance.

SKA3, negatively regulated by miR-128-3p, promotes the progression of non-small-cell lung cancer

Aim: To investigate the effects of SKA3 on cell proliferation and metastasis in non-small-cell lung cancer (NSCLC) and its underlying mechanism. Methods: Immunohistochemistry was employed to analyze the expression of SKA3 in NSCLC. CCK-8 assay, EdU assay, Transwell assay and flow cytometry analysis were employed to assess cell proliferation, metastatic potential and apoptosis in vitro, respectively. A lung metastasis model was used to evaluate metastasis of NSCLC cells in vivo. A luciferase reporter gene assay was conducted to verify the targeting relationship. Results: SKA3 exhibited high expression in NSCLC tissues and cells. Overexpression of SKA3 remarkably accelerated cell proliferation and metastasis and suppressed apoptosis of NSCLC cells and promoted lung metastasis in a mouse model. miR-128-3p repressed SKA3 expression by targeting it. Conclusion: miR-128-3p inhibited the progression of NSCLC through targeting SKA3.

Transcatheter arterial chemoembolization improves clinical efficacy and life quality of patients with lung cancer and reduces adverse reactions

OBJECTIVE

To determine the clinical efficacy and safety of transcatheter arterial chemoembolization (TACE) for patients with lung cancer (LC).

METHODS

A total of 513 inpatients with LC admitted to our hospital from January 2012 to January 2020 were analyzed retrospectively. Based on different treatment methods, they were assigned into a control group (CG; n=249) for traditional bronchial artery infusion (BAI) and an experimental group (EG; n=264) for TACE, with shared chemotherapy drugs and treatment courses. The two groups were compared with respect to clinical efficacy, pre- and post-treatment pulmonary function, adverse reactions, as well as negative emotions and quality of life (QoL) scores.

RESULTS

The curative effect in EG was far superior to CG (P<0.05). In comparison with CG, the pulmonary function in EG was better and the incidence of adverse reactions was lower after treatment (P<0.05). The negative emotions and the QoL were improved in both groups, with more distinct improvement in EG compared with CG (P<0.05).

CONCLUSIONS

With higher safety and efficacy, TACE can improve the clinical efficacy and QoL of patients with LC while relieving bad mood and reducing adverse reactions.

Biogenesis, Functions, and Role of CircRNAs in Lung Cancer

CircRNAs, a class of endogenous non-coding RNAs with closed-loop structures, have attracted increasing attention because of their good stability, high specificity of tissue expression, long half-life, and highly conserved sequence. CircRNAs have multiple biological functions, including miRNA sponge, transcription regulator, protein translation, interaction with protein, RNA maturation, and so on. These functions indicate the important role of circRNAs in tumorigenesis and malignant progression and their potential as potent diagnostic biomarkers and therapeutic molecules. In recent years, an increasing body of evidence suggests that circRNAs play a crucial role in proliferation, migration, invasion, and apoptosis of lung cancer cells. Therefore, circRNAs have gradually become a research focus in the diagnosis and treatment of lung cancer patients. This review summarizes the classification, biogenesis, and function of circRNAs, and discusses the role of circRNAs in the diagnosis, prognosis, and treatment of lung cancer patients.