Circular RNA circSLC25A16 contributes to the glycolysis of non-small-cell lung cancer through epigenetic modification

Long non-coding RNAs in cancer: multifaceted roles and potential targets for immunotherapy

Cancer remains a major global health concern with high mortality rates mainly due to late diagnosis and poor prognosis. Long non-coding RNAs (lncRNAs) are emerging as key regulators of gene expression in human cancer, functioning through various mechanisms including as competing endogenous RNAs (ceRNAs) and indirectly regulating miRNA expression. LncRNAs have been found to have both oncogenic and tumor-suppressive roles in cancer, with the former promoting cancer cell proliferation, migration, invasion, and poor prognosis. Recent research has shown that lncRNAs are expressed in various immune cells and are involved in cancer cell immune escape and the modulation of the tumor microenvironment, thus highlighting their potential as targets for cancer immunotherapy. Targeting lncRNAs in cancer or immune cells could enhance the anti-tumor immune response and improve cancer immunotherapy outcomes. However, further research is required to fully understand the functional roles of lncRNAs in cancer and the immune system and their potential as targets for cancer immunotherapy. This review offers a comprehensive examination of the multifaceted roles of lncRNAs in human cancers, with a focus on their potential as targets for cancer immunotherapy. By exploring the intricate mechanisms underlying lncRNA-mediated regulation of cancer cell proliferation, invasion, and immune evasion, we provide insights into the diverse therapeutic applications of these molecules.

CircSFMBT2 Plays an Oncogenic Role in Lung Adenocarcinoma Depending on the miR-1305/SALL4 Axis

Circular RNAs (circRNAs) exhibit significant functions in diverse malignant tumors, including lung adenocarcinoma (LUAD). In this study, we aimed to elucidate the role of circRNA scm like with four mbt domains 2 (circSFMBT2) in LUAD. Quantitative real-time polymerase chain reaction (qRT-PCR), western blot assay or immunohistochemistry (IHC) assay was performed for quantification of circSFMBT2, microRNA-1305 (miR-1305), spalt like transcription factor 4 (SALL4), proliferating Cell Nuclear Antigen (PCNA) or Ki-67. 5-ethynyl-2'-deoxyuridine (EdU) assay, transwell assay and flow cytometry analysis were applied to analyze cell proliferation, metastasis and apoptosis, respectively. Mouse xenograft model was established to explore the function of circSFMBT2. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were used to estimate the relationship between miR-1305 and circSFMBT2 or SALL4. CircSFMBT2 was upregulated in LUAD and related to advanced TNM stage and poor prognosis. CircSFMBT2 knockdown suppressed cell proliferation, metastasis, glycolysis and induced apoptosis in LUAD cells in vitro as well as tumor formation in vivo. CircSFMBT2 directly targeted miR-1305, and miR-1305 inhibition reversed circSFMBT2 knockdown-mediated inhibitory effects on LUAD malignant behaviors. SALL4 was the target gene of miR-1305. MiR-1305 overexpression repressed the malignant phenotypes of LUAD cells, while SALL4 enhancement abated the effects. CircSFMBT2 aggravated the progression of LUAD by the miR-1305/SALL4 axis, which might provide a diagnostic and prognostic marker for LUAD.

TRMT10C-mediated m7G modification of circFAM126A inhibits lung cancer growth by regulating cellular glycolysis

The N7-methylguanosine (m7G) modification and circular RNAs (circRNAs) have been shown to play important roles in the development of lung cancer. However, the m7G modification of circRNAs has not been fully elucidated. This study revealed the presence of the m7G modification in circFAM126A. We propose the novel hypothesis that the methyltransferase TRMT10C mediates the m7G modification of circFAM126A and that the stability of m7G-modified circFAM126A is reduced. circFAM126A is downregulated in lung cancer and significantly inhibits lung cancer growth both in vitro and in vivo. The expression of circFAM126A correlates with the stage of lung cancer and with the tumour diameter, and circFAM126A can be used as a potential molecular target for lung cancer. The molecular mechanism by which circFAM126A increases HSP90 ubiquitination and suppresses AKT1 expression to regulate cellular glycolysis, ultimately inhibiting the progression of lung cancer, is elucidated. This study not only broadens the knowledge regarding the expression and regulatory mode of circRNAs but also provides new insights into the molecular mechanisms that regulate tumour cell metabolism and affect tumour cell fate from an epigenetic perspective. These findings will facilitate the development of new strategies for lung cancer prevention and treatment.

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

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

Circular RNA in cancer

Over the past decade, circular RNA (circRNA) research has evolved into a bona fide research field shedding light on the functional consequence of this unique family of RNA molecules in cancer. Although the method of formation and the abundance of circRNAs can differ from their cognate linear mRNA, the spectrum of interacting partners and their resultant cellular functions in oncogenesis are analogous. However, with 10 times more diversity in circRNA variants compared with linear RNA variants, combined with their hyperstability in the cell, circRNAs are equipped to influence every stage of oncogenesis. This is an opportune time to address the breadth of circRNA in cancer focused on their spatiotemporal expression, mutations in biogenesis factors and contemporary functions through each stage of cancer. In this Review, we highlight examples of functional circRNAs in specific cancers, which satisfy critical criteria, including their physical co-association with the target and circRNA abundance at stoichiometrically valid quantities. These considerations are essential to develop strategies for the therapeutic exploitation of circRNAs as biomarkers and targeted anticancer agents.

Exploring the impact of circRNAs on cancer glycolysis: Insights into tumor progression and therapeutic strategies

Cancer cells exhibit altered metabolic pathways, prominently featuring enhanced glycolytic activity to sustain their rapid growth and proliferation. Dysregulation of glycolysis is a well-established hallmark of cancer and contributes to tumor progression and resistance to therapy. Increased glycolysis supplies the energy necessary for increased proliferation and creates an acidic milieu, which in turn encourages tumor cells' infiltration, metastasis, and chemoresistance. Circular RNAs (circRNAs) have emerged as pivotal players in diverse biological processes, including cancer development and metabolic reprogramming. The interplay between circRNAs and glycolysis is explored, illuminating how circRNAs regulate key glycolysis-associated genes and enzymes, thereby influencing tumor metabolic profiles. In this overview, we highlight the mechanisms by which circRNAs regulate glycolytic enzymes and modulate glycolysis. In addition, we discuss the clinical implications of dysregulated circRNAs in cancer glycolysis, including their potential use as diagnostic and prognostic biomarkers. All in all, in this overview, we provide the most recent findings on how circRNAs operate at the molecular level to control glycolysis in various types of cancer, including hepatocellular carcinoma (HCC), prostate cancer (PCa), colorectal cancer (CRC), cervical cancer (CC), glioma, non-small cell lung cancer (NSCLC), breast cancer, and gastric cancer (GC). In conclusion, this review provides a comprehensive overview of the significance of circRNAs in cancer glycolysis, shedding light on their intricate roles in tumor development and presenting innovative therapeutic avenues.

CircSLC25A16 facilitates the development of non-small-cell lung cancer through the miR-335-5p/CISD2 axis

BACKGROUND

Non-small-cell lung cancer (NSCLC) is a common malignancy with high morbidity and mortality. Circular RNAs are widely involved in NSCLC progression. However, the mechanism of circSLC25A16 in NSCLC has not been reported.

METHODS

The expressions of circSLC25A16, microRNA-335-5p (miR-335-5p), and CDGSH iron-sulfur domain-containing protein 2 (CISD2) were monitored by quantitative real-time fluorescence polymerase chain reaction. Western blot was also carried out to measure the protein levels of CISD2, hexokinase 2 (HK2), and lactate dehydrogenase A (LDHA). For functional analysis, cell counting kit-8 assay, 5-ethynyl-2'-deoxyuridine, flow cytometry, transwell, and wound healing assays were utilized to examine cell proliferation, apoptosis, and migration. Glucose uptake and lactate production were detected using commercial kits. The relationship between miR-335-5p and circSLC25A16 or CISD2 was verified by dual-luciferase reporter and RNA immunoprecipitation assays. Furthermore, tumor xenograft was established to explore the function of circSLC25A16 in vivo.

RESULTS

CircSLC25A16 and CISD2 were overexpressed in NSCLC, but miR-335-5p was downregulated. CircSLC25A16 acted as a miR-335-5p sponge, and silencing of circSLC25A16 arrested cell proliferation, migration, and glycolysis, and promoted apoptosis, but these impacts were resumed by miR-335-5p inhibition. CISD2 was a miR-335-5p target, and overexpression of CISD2 abolished the suppressive function of miR-335-5p mimic on the malignant behavior of NSCLC cells. CircSLC25A16 could adsorb miR-335-5p to mediate CISD2 expression. Additionally, silencing circSLC25A16 restrained the growth of NSCLC tumor xenograft in vivo.

CONCLUSION

CircSLC25A16 facilitated NSCLC progression via the miR-335-5p/CISD2 axis, implying that circSLC25A16 may serve as a novel biomarker for NSCLC treatment.

EIF4A3-Induced CircDHTKD1 regulates glycolysis in non-small cell lung cancer via stabilizing PFKL

Lung cancer (LC) is one of the malignancies with the highest incidence and mortality in the world, approximately 85% of which is non-small cell lung cancer (NSCLC). Circular RNAs (circRNAs) exert multiple roles in NSCLC occurrence and development. The sequencing results in previous literature have illustrated that multiple circRNAs exhibit upregulation in NSCLC. We attempted to figure out which circRNA exerts an oncogenic role in NSLCL progression. RT-qPCR evaluated circDHTKD1 level in NSCLC tissue specimens and cells. Reverse transcription as well as RNase R digestion assay evaluated circDHTKD1 circular characterization in NSCLC cells. FISH determined circDHTKD1 subcellular distribution in NSCLC cells. Loss- and gain-of-function assays clarified circDHTKD1 role in NSCLC cell growth, tumour growth and glycolysis. Bioinformatics and RIP and RNA pull-down assessed association of circDHTKD1 with upstream molecule Eukaryotic initiation factor 4A-III (EIF4A3) or downstream molecule phosphofructokinase-1 liver type (PFKL) and insulin-like growth factor 2 mRNA binding protein 2 (IGF2BP2) in NSCLC cells. Rescue assays assessed regulatory function of PFKL in circDHTKD1-meidated NSCLC cellular phenotypes. CircDHTKD1 exhibited upregulation and stable circular nature in NSCLC cells. EIF4A3 upregulated circDHTKD1 in NSCLC cells. CircDHTKD1 exerted a promoting influence on NSCLC cell malignant phenotypes and tumour growth. CircDHTKD1 exerted a promoting influence on NSCLC glucose metabolism. CircDHTKD1 exerts a promoting influence on NSCLC glucose metabolism through PFKL upregulation. RIP and RNA pull-down showed that circDHTKD1 could bind to IGF2BP, PFKL could bind to IGF2BP2, and circDHTKD1 promoted the binding of PFKL to IGF2BP2. In addition, RT-qPCR showed that IGF2BP2 knockdown promoted PFKL mRNA degradation, suggesting that IGF2BP2 stabilized PFKL in NSCLC cells. CircDHTKD1 exhibits upregulation in NSCLC. We innovatively validate that EIF4A3-triggered circDHTKD1 upregulation facilitates NSCLC glycolysis through recruiting m6A reader IGF2BP2 to stabilize PFKL, which may provide a new direction for seeking targeted therapy plans of NSCLC.

Hsa_circ_0008133 contributes to lung cancer progression by promoting glycolysis metabolism through the miR-760/MEX3A axis

BACKGROUND

Lung cancer is a very common cancer with poor prognosis and high mortality. Circular RNAs (circRNAs) have been confirmed to be related to the occurrence of lung cancer, and circ_0008133 has been found to be possibly related to lung cancer.

METHODS

Expression of circ_0008133, miR-760, and mex-3 RNA binding family member A (MEX3A) messenger RNA (mRNA) was detected using quantitative real-time polymerase chain reaction (qRT-PCR). Cell viability, colony number, migration, and invasion were assessed using cell counting kit-8 (CCK8), colony formation, wound healing, and transwell assays. Glucose consumption and lactate production were detected using commercial kits. Protein expression was measured using western blot. Dual-luciferase reporter assay and RNA pull-down assay were used to analyze the relationships between miR-760 and circ_0008133 or MEX3A. The effects of circ_0008133 knockdown on tumor growth in vivo were examined by the nude mice expriment. Immunohistochemistry (IHC) assay analyzed Ki-67 expression.

RESULTS

Circ_0008133 and MEX3A were markedly boosted in lung cancer tissues and cells. Circ_0008133 knockdown decreased lung cancer cell viability, glucose consumption, lactate production, colony formation, migration, and invasion. In mechanism, circ_0008133 might positively regulate MEX3A expression by sponging miR-760. Additionally, knockdown of circ_0008133 inhibited tumor growth in vivo.

CONCLUSION

Circ_0008133 accelerated the progression of lung cancer by promoting glycolysis metabolism through the miR-760/MEX3A axis.

The strict regulation of HIF-1α by non-coding RNAs: new insight towards proliferation, metastasis, and therapeutic resistance strategies

The hypoxic environment is prominently witnessed in most solid tumors and is associated with the promotion of cell proliferation, epithelial-mesenchymal transition (EMT), angiogenesis, metabolic reprogramming, therapeutic resistance, and metastasis of tumor cells. All the effects are mediated by the expression of a transcription factor hypoxia-inducible factor-1α (HIF-1α). HIF-1α transcriptionally modulates the expression of genes responsible for all the aforementioned functions. The stability of HIF-1α is regulated by many proteins and non-coding RNAs (ncRNAs). In this article, we have critically discussed the crucial role of ncRNAs [such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), circular RNAs (circRNAs), Piwi-interacting RNAs (piRNAs), and transfer RNA (tRNA)-derived small RNAs (tsRNAs)] in the regulation of stability and expression of HIF-1α. We have comprehensively discussed the molecular mechanisms and relationship of HIF-1α with each type of ncRNA in either promotion or repression of human cancers and therapeutic resistance. We have also elaborated on ncRNAs that are in clinical examination for the treatment of cancers. Overall, the majority of aspects concerning the relationship between HIF-1α and ncRNAs have been discussed in this article.

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.

Circular RNA P4HB promotes glycolysis and tumor progression by binding with PKM2 in lung adenocarcinoma

BACKGROUND

Emerging evidence indicates that circular RNAs (circRNAs) play vital roles in tumor progression, including lung adenocarcinomas (LUAD). However, the mechanisms by which circRNAs promote the progression of LUAD still require further investigation.

METHODS

Quantitative real-time PCR was performed to detect the expression of circP4HB in LUAD tissues and cells. Then, Kaplan-Meier analysis was used to determine the prognostic value of circP4HB expression. We employed RNA pull-down, RNA immunoprecipitation, mass spectrometry, cells fraction, glucose consumption, lactate production, pyruvate kinase M2 (PKM2) activity, and macrophage polarization assays to uncover the underlying mechanisms of circP4HB in LUAD.

RESULTS

We found that circP4HB is upregulated in LUAD tissues and correlated with advanced TNM stages and lymph node metastasis. LUAD patients with high circP4HB expression had poor prognoses. Functionally, circP4HB promoted LUAD progression in vivo and in vitro. Upregulated circP4HB increased glucose consumption, lactate production and accelerated aerobic glycolysis in LUAD cells. Mechanically, circP4HB mainly accumulated in the cytoplasm of LUAD cells and bound with PKM2 and subsequently upregulating PKM2 enzymatic activity by increasing its tetramer formation. Additionally, circP4HB promoted M2 macrophage phenotype shift via targeting PKM2. Finally, rescue assays further confirmed that circP4HB could promote LUAD cell progression through its interaction with PKM2.

CONCLUSION

These results demonstrate that circP4HB could promote LUAD progression, indicating circP4HB might be a potential therapeutic target of LUAD.

CircPKM2 aggravates the progression of non-small cell lung cancer by regulating MTDH via miR-1298-5p

BACKGROUND

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer with high morbidity and mortality. The role of dysregulated circular RNAs (circRNAs) in human diseases are receiving more and more attention. In this study, we focused on the role and mechanism of circPKM2 in the progression of NSCLC.

METHODS

The expression levels of circPKM2, microRNA-1298-5p (miR-1298-5p) and metadherin (MTDH) in NSCLC were measured by real-time quantitative PCR (qRT-PCR) or Western blot. Cell counting kit-8 (CCK-8), colony formation, 5-ethynyl-2'-deoxyuridine (EdU) staining, flow cytometry, transwell and tube formation assays were conducted to evaluate the effects of circPKM2 on malignant phenotypes of NSCLC. Western blot was used to measure related marker protein levels.

RESULTS

CircPKM2 and MTDH were highly expressed in NSCLC tissues and cells, while miR-1298-5p was downregulated. CircPKM2 knockdown effectively suppressed cell proliferation, migration, invasion and tube formation whereas induced apoptosis in vitro. CircPKM2 had a potential targeting site with miR-1298-5p and negatively regulated the expression of miR-1298-5p. MiR-1298-5p inhibitor reversed the effect of circPKM2 knockdown on the progression of NSCLC. CircPKM2 induced MTDH expression via sponging miR-1298-5p to promote the progression of NSCLC. MiR-1298-5p directly targeted MTDH, and the addition of MTDH partially attenuated the inhibition of miR-1298-5p on the progression of NSCLC. In addition, the downregulation of circPKM2 significantly slowed down the growth of xenograft tumors in vivo.

CONCLUSION

Our findings demonstrated that circPKM2 mediated NSCLC progression via regulating miR-1298-5p/MTDH axis, providing a novel therapeutic target for NSCLC.

MicroRNA-488: A miRNA with diverse roles and clinical applications in cancer and other human diseases

MicroRNAs (miRNAs) are a class of small non-coding RNAs that post-transcriptionally regulate the expression of approximately 50 % of all protein-coding genes. They have been demonstrated to act as key regulators in various pathophysiological processes and play significant roles in a wide range of human diseases, particularly cancer. Current research highlights the aberrant expression of microRNA-488 (miR-488) in multiple human diseases and its critical involvement in disease initiation and progression. Moreover, the expression level of miR-488 has been linked to clinicopathological features and patient prognosis across different diseases. However, a comprehensive systematic review of miR-488 is lacking. Therefore, our study aims to consolidate the current knowledge surrounding miR-488, with a primary focus on its emerging biological functions, regulatory mechanisms, and potential clinical applications in human diseases. Through this review, we aim to establish a comprehensive understanding of the diverse roles of miR-488 in the development of various diseases.

Molecular profile of non-coding RNA-mediated glycolysis control in human cancers

The glycolysis is a common characteristic of cancer and it is responsible for providing enough energy to ensure growth. The glycolysis suppression is beneficial in tumor growth reduction. The stimulation/inhibition of glycolysis in cancer is tightly regulated by ncRNAs. The regulation of glycolysis by ncRNAs can influence proliferation and therapy response of tumor. The miRNAs are capable of inactivating enzymes responsible for glycolysis and suppressing signaling networks resulting in glycolysis induction. By regulation of glycolysis, miRNAs can affect therapy response. The lncRNAs and circRNAs follow a same pathway and by targeting glycolysis, they affect progression and therapy response of tumor. Noteworthy, lncRNAs and circRNAs sponge miRNAs in glycolysis mechanism control in tumor cells. Furthermore, ncRNA-mediated regulation of glycolysis mechanism can influence metastasis to organs of body. The ncRNAs regulating glycolysis are reliable biomarkers in cancer patients and more importantly, exosomal ncRNAs due to their presence in body fluids, are minimally-invasive biomarkers.

Circular RNAs in hepatocellular carcinoma: biogenesis, function, and pathology

Hepatocellular carcinoma (HCC) is one of the most common causes of cancer-related death worldwide. Both genetic and environmental factors through a multitude of underlying molecular mechanisms participate in the pathogenesis of HCC. Recently, numerous studies have shown that circular RNAs (circRNAs), an emerging class of non-coding RNAs characterized by the presence of covalent bonds linking 3' and 5' ends, play an important role in the initiation and progression of cancers, including HCC. In this review, we outline the current status of the field of circRNAs, with an emphasis on the functions and mechanisms of circRNAs in HCC and its microenvironment. We also summarize and discuss recent advances of circRNAs as biomarkers and therapeutic targets. These efforts are anticipated to throw new insights into future perspectives about circRNAs in basic, translational and clinical research, eventually advancing the diagnosis, prevention and treatment of HCC.

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.

Circular RNAs-New Kids on the Block in Cancer Pathophysiology and Management

The ever-increasing number of cancer cases and persistently high mortality underlines the urgent need to acquire new perspectives for developing innovative therapeutic approaches. As the research on protein-coding genes brought significant yet only incremental progress in the development of anticancer therapy, much attention is now devoted to understanding the role of non-coding RNAs (ncRNAs) in various types of cancer. Recent years have brought about the awareness that ncRNAs recognized previously as "dark matter" are, in fact, key players in shaping cancer development. Moreover, breakthrough discoveries concerning the role of a new group of ncRNAs, circular RNAs, have evidenced their high importance in many diseases, including malignancies. Therefore, in the following review, we focus on the role of circular RNAs in cancer, particularly in cancer stem-like cells, summarize their mechanisms of action, and provide an overview of the state-of-the-art toolkits to study them.

The significance of the crosstalk between ubiquitination or deubiquitination and ncRNAs in non-small cell lung cancer

Lung cancer (LC) remains the leading cause of cancer-related deaths worldwide, with extremely high morbidity and mortality rates. Non-small cell lung cancer (NSCLC) is the most critical type of LC. It seriously threatens the life and health of patients because of its early metastasis, late clinical symptoms, limited early screening methods, and poor treatment outcomes. Non-coding RNAs (ncRNAs), including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), participate in cell proliferation, metastasis, and chemoresistance. Several previous studies have proven that ncRNAs are vital regulators of tumorigenesis. Ubiquitination plays the most crucial role in protein post-translational modification (PTM). Deubiquitination and ubiquitination form a homeostasis. In summary, ubiquitination and deubiquitination play essential roles in mediating the degradation or overexpression of a range of crucial proteins in various cancers. A growing number of researchers have found that interactions between ncRNAs and ubiquitination (or deubiquitination) play a crucial role in NSCLC. This review presents several typical examples of the important effects of ncRNAs and ubiquitination (or deubiquitination) in NSCLC, aiming to provide more creative ideas for exploring the diagnosis and treatment of NSCLC.

Circular RNA, circular RARS, promotes aerobic glycolysis of non-small-cell lung cancer by binding with LDHA

PURPOSE

Accumulating evidence has highlighted the critical roles of circular RNAs (circRNAs) in non-small-cell lung cancer (NSCLC). This study aims to unveil the roles of circRARS (circular RARS) (hsa_circ_0001551) in NSCLC.

METHODS

Quantitative real-time PCR was used to determine the expression of circRARS in NSCLC tissues and cells. Kaplan-Meier analysis was used to determine the prognostic value of circRARS expression. CCK8, transwell, and wound healing assays were used to assess the proliferation, invasion, and migration abilities of NSCLC cells. RNA pull-down, cell fraction, glucose consumption, lactate production, and lactate dehydrogenase activity assays were conducted to explore the potential mechanisms of circRARS in NSCLC.

RESULTS

circRARS is upregulated in NSCLC tissues and positively correlated with smoking status, lymph node metastasis, and higher tumor stages. NSCLC patients with high expression of circRARS have poor overall survival. Functional assays demonstrated that circRARS accelerated the proliferation, invasion, and migration of NSCLC cells in vitro. The cell fraction suggested that circRARS mainly accumulated in cytoplasm and the RNA pull-down assay showed lactate dehydrogenase (LDHA) could bind with circRARS. Furthermore, circRARS positively regulates LDHA activity and LDHA expression at the transcription level. Moreover, downregulated circRARS decreases glucose consumption and lactate production and compromises aerobic glycolysis in NSCLC cells. Finally, rescue assays showed circRARS could promote NSCLC cell proliferation by regulating LDHA activity.

CONCLUSION

This study shows that circRARS can promote glycolysis and tumor progression in NSCLC by regulating LDHA.

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

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

Circular RNAs: Emerging regulators of glucose metabolism in cancer

Aberrant glucose metabolism is one of the most striking characteristics of metabolic reprogramming in cancer. Thus, clarifying the regulatory mechanism of glucose metabolism is crucial to understanding tumor progression and developing novel therapeutic strategies for cancer patients. Recent developments in circular RNAs have explained the regulatory mechanism of glucose metabolism from a new dimension. In this review, we briefly summarize the recent advances in circRNA research on cancer glucose metabolism and emphasize the different regulatory mechanisms, including acting as miRNA sponges, interacting with proteins and being translated into proteins. Additionally, we discuss the future research directions of circular RNAs in the field of glucose metabolism.

Circ_0006646 Accelerates the Growth and Metastasis of Cervical Cancer by Elevating RRM2 Through miR-758-3p

Cervical cancer (CC) is the fourth most common cancer in women, and circular RNAs (circRNAs) have been shown to regulate CC development. However, the role of circ_0006646 in CC progression is still unclear. The levels of circ_0006646, miR-758-3p, and ribonucleotide reductase regulatory subunit M2 (RRM2) were evaluated by quantitative real-time PCR. Cell proliferation was tested by cell counting kit 8 and 5-ethynyl-2'-deoxyuridine assays. Flow cytometry was used to test cell apoptosis. Migration and invasion were estimated by transwell assay. Western blot assay was performed to examine protein expression. Dual-luciferase reporter assay, RIP assay, and RNA pull down assay were used to analyze the connection between miR-758-3p and circ_0006646 or RRM2. Tumor growth was detected by in vivo experiments. Exosomes were isolated form CC patients and healthy controls. Circ_0006646 expression was elevated in CC cells, and its knockdown suppressed CC cell growth, migration, and invasion. MiR-758-3p was sponged by circ_0006646, and RRM2 was targeted by miR-758-3p. In addition, the effects of circ_0006646 depletion on CC cell progression were overturned by miR-758-3p inhibitor, and either RRM2 overexpression reversed those effects of miR-758-3p overexpression on CC cell progression. Circ_0006646 was highly expressed in the exosomes of CC patients. Circ_0006646 expedited CC cell growth and metastasis by regulating miR-758-3p/RRM2 axis, and exosomal circ_0006646 might be a potential diagnostic indicator of CC.

LDHA: The Obstacle to T cell responses against tumor

Immunotherapy has become a successful therapeutic strategy in certain solid tumors and hematological malignancies. However, this efficacy of immunotherapy is impeded by limited success rates. Cellular metabolic reprogramming determines the functionality and viability in both cancer cells and immune cells. Extensive research has unraveled that the limited success of immunotherapy is related to immune evasive metabolic reprogramming in tumor cells and immune cells. As an enzyme that catalyzes the final step of glycolysis, lactate dehydrogenase A (LDHA) has become a major focus of research. Here, we have addressed the structure, localization, and biological features of LDHA. Furthermore, we have discussed the various aspects of epigenetic regulation of LDHA expression, such as histone modification, DNA methylation, N6-methyladenosine (m6A) RNA methylation, and transcriptional control by noncoding RNA. With a focus on the extrinsic (tumor cells) and intrinsic (T cells) functions of LDHA in T-cell responses against tumors, in this article, we have reviewed the current status of LDHA inhibitors and their combination with T cell-mediated immunotherapies and postulated different strategies for future therapeutic regimens.

Crosstalk between metabolic reprogramming and epigenetics in cancer: updates on mechanisms and therapeutic opportunities

Reversible, spatial, and temporal regulation of metabolic reprogramming and epigenetic homeostasis are prominent hallmarks of carcinogenesis. Cancer cells reprogram their metabolism to meet the high bioenergetic and biosynthetic demands for vigorous proliferation. Epigenetic dysregulation is a common feature of human cancers, which contributes to tumorigenesis and maintenance of the malignant phenotypes by regulating gene expression. The epigenome is sensitive to metabolic changes. Metabolism produces various metabolites that are substrates, cofactors, or inhibitors of epigenetic enzymes. Alterations in metabolic pathways and fluctuations in intermediate metabolites convey information regarding the intracellular metabolic status into the nucleus by modulating the activity of epigenetic enzymes and thus remodeling the epigenetic landscape, inducing transcriptional responses to heterogeneous metabolic requirements. Cancer metabolism is regulated by epigenetic machinery at both transcriptional and post‐transcriptional levels. Epigenetic modifiers, chromatin remodelers and non‐coding RNAs are integral contributors to the regulatory networks involved in cancer metabolism, facilitating malignant transformation. However, the significance of the close connection between metabolism and epigenetics in the context of cancer has not been fully deciphered. Thus, it will be constructive to summarize and update the emerging new evidence supporting this bidirectional crosstalk and deeply assess how the crosstalk between metabolic reprogramming and epigenetic abnormalities could be exploited to optimize treatment paradigms and establish new therapeutic options. In this review, we summarize the central mechanisms by which epigenetics and metabolism reciprocally modulate each other in cancer and elaborate upon and update the major contributions of the interplays between epigenetic aberrations and metabolic rewiring to cancer initiation and development. Finally, we highlight the potential therapeutic opportunities for hematological malignancies and solid tumors by targeting this epigenetic‐metabolic circuit. In summary, we endeavored to depict the current understanding of the coordination between these fundamental abnormalities more comprehensively and provide new perspectives for utilizing metabolic and epigenetic targets for cancer treatment.

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 Down-Regulation of Circ_0059707 in Acute Myeloid Leukemia Promotes Cell Growth and Inhibits Apoptosis by Regulating miR-1287-5p

Acute myeloid leukemia (AML) is the most common type of hematological malignancy. Recently, an increasing number of reports have shown that many circular RNAs can act as effective targets for AML. However, the roles of circ_0059707 in AML remain largely unclear. In this study, we found that the expression levels of circ_0059707 were significantly decreased in AML patients with respect to normal controls (p < 0.001). Low expression levels of circ_0059707 were also associated with a poor prognosis. Furthermore, circ_0059707 overexpression inhibited cell growth and promoted apoptosis in leukemia cells, compared with control cells. Circ_0059707- and empty plasmid-transfected cells were injected subcutaneously into BALB/c nude mice. We found that the tumor volume was significantly lower in mice in the circ_0059707 group than in control mice (p < 0.01). Nuclear pyknosis, nuclear fragmentation, nuclear dissolution, and cell necrosis were observed in the circ_0059707 group by HE staining. CircInteractome analysis showed that 25 microRNAs (miRNAs), including miR-1287-5p, ©-miR-1825, a©hsa-miR-326, may be potential targets for circ_0059707. The expression of these miRNAs was analyzed in both the GEO GSE51908 and the GSE142700 databases. miR-1287-5p expression was lower in AML patients compared with controls in both the GSE51908 and the GSE142700 datasets. Moreover, we demonstrated that miR-1287-5p expression was down-regulated in AML patients and up-regulated in circ_0059707-overexpressing cells. Collectively, our research demonstrated that the down-regulation of circ_0059707 was highly evident in de novo AML patients. Our analysis also demonstrated that circ_0059707 inhibited cell growth and promoted apoptosis by up-regulating miR-1287-5p.

Long Noncoding RNAs and Circular RNAs in the Metabolic Reprogramming of Lung Cancer: Functions, Mechanisms, and Clinical Potential

As key regulators of gene function, long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs) are generally accepted to be involved in lung cancer pathogenesis and progression. Recent research has clarified the phenomenon of metabolic reprogramming in lung cancer because of its significant role in tumor proliferation, migration, invasion, metastasis, and other malignant biological behaviors. Emerging evidence has also shown a relationship between the aberrant expression of lncRNAs and circRNAs and metabolic reprogramming in lung cancer tumorigenesis. This review provides insight regarding the roles of different lncRNAs and circRNAs in lung cancer metabolic reprogramming, by how they target transporter proteins and key enzymes in glucose, lipid, and glutamine metabolic signaling pathways. The clinical potential of lncRNAs and circRNAs as early diagnostic biomarkers and components of therapeutic strategies in lung cancer is further discussed, including current challenges in their utilization from the bench to the bedside and how to adopt a proper delivery system for their therapeutic use.

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

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

Identification of potential circular RNA biomarkers in lung adenocarcinoma: A bioinformatics analysis and retrospective clinical study

Non-small cell lung cancer (NSCLC) is one of the leading causes of cancer-associated mortality. Lung adenocarcinoma (LAC) is the most prevalent pathological subtype of NSCLC and accounts for ~40% of all lung cancer mortalities. There remains an urgent demand for the identification of novel biomarkers for the diagnosis and development of therapeutic strategies for LAC. In the present study, the profiles of the differentially-expressed circular RNAs (circRNAs) in LAC tissues compared with those in their corresponding non-cancerous tissues were obtained after analyzing the circRNA microarray dataset GSE101586. The expression pattern of the indicated circRNAs in the LAC tissues were subsequently verified using reverse transcription-quantitative PCR (RT-qPCR). The potential prognostic significance of these circRNAs in patients with LAC were then analyzed in a retrospective clinical study. A circRNA-microRNA (miR or miRNA)-mRNA regulatory network in LAC was established by using Cytoscape. In addition, a protein-protein interaction (PPI) network was plotted using the Search Tool for the Retrieval of Interacting Genes/Proteins and visualized through Cytoscape. The prognostic value of the hub genes found was then analyzed based on the Gene Expression Profiling Interactive Analysis database. In total, four differentially-expressed circRNAs were obtained from the GSE101586 microarray dataset, three of which (hsa_circ_0006220, hsa_circ_0072088 and hsa_circ_0001666) were confirmed by RT-qPCR to be highly expressed in LAC tissues. This retrospective clinical study revealed that higher expression levels of these three circRNAs were associated with poorer prognoses in patients with LAC. In addition, siRNA-mediated knockdown of these circRNAs was found to inhibit cell proliferation, migration and invasion in LAC cells. Following analysis of the molecular mechanism underlying these circRNAs, eight miRNAs, namely miR-520f, miR-1261, miR-1270, miR-620, miR-188-3p, miR-516b, miR-940 and miR-661, were identified with potential binding sites for these three circRNAs. Subsequently, 232 overlapped genes from the 795 upregulated genes in the LAC samples from The Cancer Genome Atlas database and 7,829 predicted target genes of the list of eight aforementioned miRNAs were obtained. A circRNA-miRNA-mRNA network was then constructed. A PPI network was established, with six hub genes, namely kinesin family member (KIF) 2C, KIF18B, maternal embryonic leucine zipper kinase, baculoviral IAP repeat-containing 5, polo-like kinase 1 and cytoskeleton-associated protein 2-like, determined from this network. Higher expression levels of each of these hub genes were found to be associated with poorer prognoses of patients with LAC. To conclude, data from the present study suggested that circRNAs hsa_circ_0006220, hsa_circ_0072088 and hsa_circ_0001666 have the potential to be viable biomarkers and therapeutic targets for LAC.

Immune effects of PI3K/Akt/HIF-1α-regulated glycolysis in polymorphonuclear neutrophils during sepsis

Background

Effective removal of pathogenic bacteria is key to improving the prognosis of sepsis. Polymorphonuclear neutrophils (PMNs) are the most important components of innate cellular immunity and play vital roles in clearing pathogenic bacteria. However, the metabolic characteristics and immunomodulatory pathways of PMNs during sepsis have not been investigated. In the present study, we explored the immune metabolism characteristics of PMNs and the mechanism by which neutrophilic glycolysis is regulated during sepsis.

Methods

Metabolomics analysis was performed on PMNs isolated from 14 septic patients, 26 patients with acute appendicitis, and 19 healthy volunteers. Transcriptome analysis was performed on the PMNs isolated from the healthy volunteers and the patients with sepsis to assess glycolysis and investigate its mechanism. Lipopolysaccharide (LPS) was used to stimulate the neutrophils isolated from the healthy volunteers at different time intervals to build an LPS-tolerant model. Chemotaxis, phagocytosis, lactate production, oxygen consumption rate (OCR), and extracellular acidification rate (ECAR) were evaluated.

Results

Transcriptomics showed significant changes in glycolysis and the mTOR/HIF-1α signaling pathway during sepsis. Metabolomics revealed that the Warburg effect was significantly altered in the patients with sepsis. We discovered that glycolysis regulated PMNs’ chemotaxis and phagocytosis functions during sepsis. Lactate dehydrogenase A (LDHA) downregulation was a key factor in the inhibition of glycolysis in PMNs. This study confirmed that the PI3K/Akt-HIF-1α pathway was involved in the LDHA expression level and also influenced PMNs’ chemotaxis and phagocytosis functions.

Conclusions

The inhibition of glycolysis contributed to neutrophil immunosuppression during sepsis and might be controlled by PI3K/Akt-HIF-1α pathway-mediated LDHA downregulation. Our study provides a scientific theoretical basis for the management and treatment of patients with sepsis and promotes to identify therapeutic target for the improvement of immune function in sepsis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-03893-6.

CircACC1 Promotes NSCLC Proliferation via miR-29c-3p/MCL-1 Signaling Pathway

Non-small cell lung cancer remains the leading cause of cancer-related deaths worldwide with high morbidity and mortality. There is an urgent need to reveal new molecular mechanisms that contribute to NSCLC progression to facilitate drug development and to improve overall survival. Much attention has been paid to the role of circRNAs in NSCLC development. However, the knowledge of circRNAs in NSCLC is still limited, and need to be further explored. The dysregulation of circACC1 was evaluated by qRT-PCR in NSCLC samples and cell lines. The oncogenic role of circACC1 in NSCLC progression was analyzed by CCK8 and colony formation assays. The interaction between the circACC1 and miR-29c-3p, as well as MCL-1, was verified by qRT-PCR, Western blot, luciferase reporter assay, and RIP experiment. Elevated levels of circACC1 were found in NSCLC patients and were negatively correlated with OS. Ectopic expression of circACC1 promoted the capacity of cell growth and clonogenicity, while the inhibition of circACC1 decreased the proliferation and clonogenicity potential. Mechanism studies elucidated that circACC1 contributes to cell growth via directly binding to miR-29c-3p. Transfection of miR-29c-3p mimic blocked circACC1 mediated NSCLC cell proliferation. MCL-1 is a downstream target of miR-29c-3p in NSCLC cells. The circACC1/miR-29c-3p/MCL-1 axis is important in NSCLS proliferation.

Circ_0006006 facilitates non-small cell lung cancer progression by modulating miR-924/SRSF7 axis

BACKGROUND

Non-small cell lung cancer (NSCLC) is an aggressive tumor with high mortality. Circular RNAs (CircRNAs) played crucial roles in the development of cancers, including NSCLC. In this study, the action of circ_0006006 in NSCLC was investigated.

METHODS

Using real-time quantitative PCR (RT-qPCR), the relative gene expression was detected. The structure of circ_0006006 was identified using RNase R digestion and Actinomycin D treatment. The functional role of circ_0006006 in cell proliferation, migration, invasion, apoptosis and angiogenesis was explored using Cell Counting Kit-8 (CCK-8), EdU, colony formation, wound healing, transwell, flow cytometry, and tube formation assays, respectively. Using western blot, the relative proteins expression was measured. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were employed to verify the correlation between microRNA-924 (miR-924) and circ_0006006 or serine/arginine-rich splicing factor 7 (SRSF7). Xenograft tumor experiment was used to investigate the effect of circ_0006006 on tumor growth in vivo. Immunohistochemistry (IHC) assay was performed to detect Ki-67, Bax, Bcl-2 and SRSF7 expression in tissues of mice.

RESULTS

Circ_0006006 was increased in NSCLC tissues and cells. Loss-of-function assays demonstrated that circ_0006006 silencing repressed the proliferative ability, cell migration and invasion, angiogenesis, and promoted cell apoptosis in A549 and H1299 cells. Follow-up mechanism experiments depicted that circ_0006006 sponged miR-924 and miR-924 inhibitor rescued circ_0006006 knockdown-mediated inhibition effect on the progression of NSCLC. Additionally, the inhibition effect of circ_0006006 knockdown on SRSF7 expression was reversed by miR-924 inhibitor. Moreover, the suppressive effect of miR-924 on NSCLC progression was reversed by SRSF7 overexpression. Xenograft tumor experiment unveiled that circ_0006006 knockdown inhibited tumor growth in vivo.

CONCLUSION

Circ_0006006 stimulated NSCLC progression by targeting miR-924 to regulate SRSF7 expression.

CircRNA75 and CircRNA72 Function as the Sponge of MicroRNA-200 to Suppress Coelomocyte Apoptosis Via Targeting Tollip in Apostichopus japonicus

Circular RNAs (circRNAs) act as essential regulators in many biological processes, especially in mammalian immune response. Nonetheless, the functions and mechanisms of circRNAs in the invertebrate immune system are largely unclarified. In our previous work, 261 differentially expressed circRNAs potentially related to the development of Apostichopus japonicus skin ulceration syndrome (SUS), which is a major problem restricting the sea cucumber breeding industry, were identified by genome-wide screening. In this study, via miRanda analysis, both circRNA75 and circrRNA72 were shown to share the miR-200 binding site, a key microRNA in the SUS. The two circRNAs were verified to be increased significantly in LPS-exposed primary coelomocytes, similar to the results of circRNA-seq in sea cucumber under Vibrio splendidus-challenged conditions. A dual-luciferase assay indicated that both circRNA75 and circRNA72 could bind miR-200 in vivo, in which circRNA75 had four binding sites of miR-200 and only one for circRNA72. Furthermore, we found that miR-200 could bind the 3’-UTR of Toll interacting protein (Tollip) to negatively mediate the expression of Tollip. Silencing Tollip increased primary coelomocyte apoptosis. Consistently, inference of circRNA75 and circRNA72 could also downregulate Tollip expression, thereby increasing the apoptosis of primary coelomocytes, which could be blocked by miR-200 inhibitor treatment. Moreover, the rate of si-circRNA75-downregulated Tollip expression was higher than that of si-circRNA72 under an equivalent amount. CircRNA75 and circRNA72 suppressed coelomocyte apoptosis by sponging miR-200 to promote Tollip expression. The ability of circRNA to adsorb miRNA might be positively related to the number of binding sites for miRNA.

CircTUBGCP3 facilitates the tumorigenesis of lung adenocarcinoma by sponging miR-885-3p

Background

Circular RNAs (circRNAs) act pivotal roles in the progression of multiple malignancies. However, the underlying mechanisms by which hsa_circ_0007031 (circTUBGCP3) contributes to lung adenocarcinoma (LAC) remain largely unknown.

Methods

The association of circTUBGCP3 expression with clinicopathological characteristics and prognosis in patients with LAC was determined by RT-qPCR and fluorescence in situ hybridization. The in vitro functional experiments as well as a subcutaneous tumorigenesis model were executed to estimate the role of circTUBGCP3 in LAC cells. The interaction between circTUBGCP3 and miR-885-3p was confirmed by RNA immunoprecipitation, luciferase gene report and RT-qPCR assays. The effects of circTUBGCP3 on miR-885-3p-mediated Wnt10b/β-catenin signaling were evaluated by Western blot.

Results

The upregulation of circTUBGCP3 or downregulation of miR-885-3p was associated with the pathological stage and poor survival in patients with LAC. Restored expression of circTUBGCP3 facilitated the growth and invasion of LAC cells, but knockdown of circTUBGCP3 harbored the opposite effects. In mechanism, circTUBGCP3 could act as a sponge of miR-885-3p, which suppressed the cell proliferation and colony formation and attenuated the tumor-promoting effects of circTUBGCP3. Wnt10b as a target of miR-885-3p could be upregulated be circTUBGCP3 and indicate poor survival in patient with LAC.

Conclusions

Our findings demonstrated that circTUBGCP3 promoted LAC progression by sponging miR-885-3p, and might represent a prognostic factor for LAC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02356-2.

The emerging roles of circular RNAs in vessel co-option and vasculogenic mimicry: clinical insights for anti-angiogenic therapy in cancers

Unexpected resistance to anti-angiogenic treatment prompted the investigation of non-angiogenic tumor processes. Vessel co-option (VC) and vasculogenic mimicry (VM) are recognized as primary non-angiogenic mechanisms. In VC, cancer cells utilize pre-existing blood vessels for support, whereas in VM, cancer cells channel and provide blood flow to rapidly growing tumors. Both processes have been implicated in the development of tumor and resistance to anti-angiogenic drugs in many tumor types. The morphology, but rare molecular alterations have been investigated in VC and VM. There is a pressing need to better understand the underlying cellular and molecular mechanisms. Here, we review the emerging circular RNA (circRNA)-mediated regulation of non-angiogenic processes, VC and VM.

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.

Regulating COX10-AS1 / miR-142-5p / PAICS axis inhibits the proliferation of non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is one of the main causes of death in the world. To improve the diagnostic level and find new biological targets，GSE datasets were selected from GEO databaseto analyze the differential expression genes and construct ceRNA network. Cell apoptosis detection showed that both the early and late apoptosis rates were increased after inhibition of COX10-AS1. Glycolysis cell-based assay also found that the content of L-lactate decreased significantly after using miR-142-5p mimics but increased after using si-COX10-AS1. Dual-luciferase reporter analysis showed that the luciferase activity of PAICS-WT reporter vector was inhibited by miR-142-5p mimics, but there was no significant change in PAICS-MUT reporter vector after transfection of miR-142-5p mimics. And overexpression of miR-142-5p reduced the level of PAICS, but inhibition of miR-142-5p expression increased the expression of PAICS. After using COX10-AS1, the expression of PAICS inhibited by miR-142-5p was restored. Through bioinformatics analysis, we constructed the COX10-AS1/miR-142-5p/PAICS axis, which is a ceRNA regulatory network. We confirmed that COX10-AS1 down-expression can restore the inhibitory effect of miR-142-5p on PAICS, promote the apoptosis of NSCLC cells, and inhibit the proliferation of NSCLC cells. This process may be mediated by the activation of glycolysis pathway. The glycolysis-related gene PAICS may be a new and significant target for the regulation of the development of NSCLC.

Potential therapeutics using tumor-secreted lactate in nonsmall cell lung cancer

Targeted-therapy failure in treating nonsmall cell lung cancer (NSCLC) frequently occurs because of the emergence of drug resistance and genetic mutations. The same mutations also result in aerobic glycolysis, which further antagonizes outcomes by localized increases in lactate, an immune suppressor. Recent evidence indicates that enzymatic lowering of lactate can promote an oncolytic immune microenvironment within the tumour. Here, we review factors relating to lactate expression in NSCLC and the utility of lactate oxidase (LOX) for governing therapeutic delivery, its role in lactate oxidation and turnover, and relationships between lactate depletion and immune cell populations. The lactate-rich characteristic of NSCLC provides an exploitable property to potentially improve NSCLC outcomes and design new therapeutic strategies to integrate with conventional therapies.

Circular RNAs in Lung Cancer: Recent Advances and Future Perspectives

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

Circular RNAs Regulate Glucose Metabolism in Cancer Cells

Circular RNAs (circRNAs) were originally thought to result from RNA splicing errors. However, it has been shown that circRNAs can regulate cancer onset and progression in various ways. They can regulate cancer cell proliferation, differentiation, invasion, and metastasis. Moreover, they modulate glucose metabolism in cancer cells through different mechanisms such as directly regulating glycolytic enzymes and glucose transporter (GLUT) or indirectly regulating signal transduction pathways. In this review, we elucidate on the role of circRNAs in regulating glucose metabolism in cancer cells, which partly explains the pathogenesis of malignant tumors, and provides new therapeutic targets or new diagnostic and prognostic markers for human cancers.

Circular RNAs regulate cancer-related signaling pathways and serve as potential diagnostic biomarkers for human cancers

Circular RNAs (circRNAs) are RNAs that have an important role in various pathological processes, including cancer. After the usage of high-throughput RNA sequencing, many circRNAs were found to be differentially expressed in various cancer cell lines and regulate cell signaling pathways by modulating particular gene expressions. Understanding their role in these pathways and what cancers they are found in can set the stage for identifying diagnostic and prognostic biomarkers and therapeutic targets of cancer. This paper will discuss which circRNAs are found in different cancers and what mechanisms they use to upregulate or downregulate certain cellular components.

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.

CircPUM1 promotes cell growth and glycolysis in NSCLC via up-regulating METTL3 expression through miR-590-5p

RNA pumilio RNA binding family member 1 (circPUM1) has been reported to play important roles in the tumorigenesis of several cancers. However, the underlying molecular role of circPUM1 in non-small cell lung cancer (NSCLC) progression remains unknown. The qRT-PCR and western blot were used to evaluate the expression of RNAs and proteins. In vitro cell proliferation assays, flow cytometric and glucose metabolism analyses were performed to test the effects of circPUM1 and its target on NSCLC cell growth and glycolysis. The interaction between microRNA (miR)-590-5p and circPUM1 or methyltransferase like 3 (METTL3) was analyzed by using dual-luciferase reporter, pull-down or RNA immunoprecipitation (RIP) assays. Murine xenograft model was established to conduct in vivo experiments. CircPUM1 was highly expressed in NSCLC tissues and cell lines. CircPUM1 knockdown suppressed cell proliferation, cell cycle and glycolysis in vitro. Moreover, circPUM1 directly bound to miR-590-5p, and miR-590-5p inhibitor reversed the inhibitory effects of circPUM1 knockdown on NSCLC carcinogenesis. Additionally, miR-590-5p suppressed NSCLC progression by directly targeting and regulating METTL3. Importantly, circPUM1 could regulate METTL3 in NSCLC cells through miR-590-5p. In addition, it was also proved circPUM1 silencing impeded tumor growth and glycolysis in the murine xenograft model by regulating miR-590-5p/METTL3 axis. CircPUM1 promoted NSCLC tumor growth and glycolysis through sequestering miR-590-5p and up-regulating METTL3, providing an improved understanding of NSCLC tumorigenesis and a potential therapeutic target for NSCLC therapy.

Tip of the Iceberg: Roles of CircRNAs in Cancer Glycolysis

Warburg effect reflects that tumor cells tend to generate energy by aerobic glycolysis rather than oxidative phosphorylation (OXPHOS), thus promoting the development of malignant tumors. As a kind of non-coding RNA, circular RNA (circRNA) is characterized by a closed ring structure and emerges as a regulator of cancer metabolism. Mounting studies revealed that circRNA can regulate the cancer metabolism process through affecting the expression of glycolysis relevant enzymes, transcription factors (TFs), and signaling pathways. In this review, we comprehensively analyzed and concluded the mechanism of circRNA regulating glycolysis, hoping to deepen the cognition of the cancer metabolic regulatory network and to reap huge fruits in targeted cancer treatment.

Circular RNA circRNA_0000094 sponges microRNA-223-3p and up-regulate F-box and WD repeat domain containing 7 to restrain T cell acute lymphoblastic leukemia progression

Circular RNAs (circRNAs) exert crucial regulatory effects in the pathogenesis of multiple tumors. This work aimed to probe into the role of circ_0000094 in T cell acute lymphoblastic leukemia (T-ALL). In this work, quantitative real-time polymerase chain reaction (qRT-PCR) was applied to quantify circ_0000094, miR-223-3p, and F-box and WD repeat domain containing 7 (FBW7) mRNA expressions in lymph node samples from T-ALL patients; Western blot was adopted to examine FBW7 protein expression in T-ALL cells; cell proliferation was detected by cell counting kit-8 (CCK-8) experiment; apoptosis was examined by flow cytometry; Transwell experiments were applied to assess T-ALL cell migration and invasion; the interactions among circ_0000094 and miR-223-3p, and miR-223-3p and FBW7 were validated by bioinformatics prediction, dual-luciferase reporter gene assay, and RNA immunoprecipitation experiment. We reported that, circ_0000094 expression was markedly reduced in T-ALL and circ_0000094 was predominantly located in the cytoplasm; gain-of-function and loss-of-function assays verified that circ_0000094 overexpression remarkably suppressed T-ALL cell proliferation, migration, and invasion, and enhanced apoptosis while knocking down circ_0000094 enhanced the malignant phenotypes of T-ALL cells; "rescue experiments" implied that miR-223-3p mimics partly reversed the inhibitory effects on the malignant phenotype of T-ALL cells due to the circ_0000094 up-regulation; circ_0000094 was proved to be a molecular sponge for miR-223-3p, and it could up-regulate the expression of FBW7 via repressing miR-223-3p expression. Taken together, it was concluded that circ_0000094 impedes T-ALL progression by modulating the miR-223-3p/FBW7 axis.

The Role of PKM2 in Metabolic Reprogramming: Insights into the Regulatory Roles of Non-Coding RNAs

Pyruvate kinase is a key regulator in glycolysis through the conversion of phosphoenolpyruvate (PEP) into pyruvate. Pyruvate kinase exists in various isoforms that can exhibit diverse biological functions and outcomes. The pyruvate kinase isoenzyme type M2 (PKM2) controls cell progression and survival through the regulation of key signaling pathways. In cancer cells, the dimer form of PKM2 predominates and plays an integral role in cancer metabolism. This predominance of the inactive dimeric form promotes the accumulation of phosphometabolites, allowing cancer cells to engage in high levels of synthetic processing to enhance their proliferative capacity. PKM2 has been recognized for its role in regulating gene expression and transcription factors critical for health and disease. This role enables PKM2 to exert profound regulatory effects that promote cancer cell metabolism, proliferation, and migration. In addition to its role in cancer, PKM2 regulates aspects essential to cellular homeostasis in non-cancer tissues and, in some cases, promotes tissue-specific pathways in health and diseases. In pursuit of understanding the diverse tissue-specific roles of PKM2, investigations targeting tissues such as the kidney, liver, adipose, and pancreas have been conducted. Findings from these studies enhance our understanding of PKM2 functions in various diseases beyond cancer. Therefore, there is substantial interest in PKM2 modulation as a potential therapeutic target for the treatment of multiple conditions. Indeed, a vast plethora of research has focused on identifying therapeutic strategies for targeting PKM2. Recently, targeting PKM2 through its regulatory microRNAs, long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) has gathered increasing interest. Thus, the goal of this review is to highlight recent advancements in PKM2 research, with a focus on PKM2 regulatory microRNAs and lncRNAs and their subsequent physiological significance.

Circular RNA CircCDYL Regulates Proliferation and Apoptosis in Non-Small Cell Lung Cancer Cells by Sponging miR-185-5p and Upregulating TNRC6A

Aim

A series of research reveal that circular RNA (circRNA) plays a vital role in regulating the development of tumor cells. In this research, we would explore the role and mechanism of circCDYL in non-small cell lung cancer (NSCLC).

Methods

RT-PCR was performed to detect the expression of circCDYL in NSCLC tissues, plasma, and cell lines. The tumor cell proliferation ability was evaluated by clone formation assay, and cell cycle determination. Flow cytometry was used to detect apoptosis in NSCLC cell lines. Western blot and RT-PCR were used to assess the expression of proteins and genes. Luciferase assay was performed to confirm the relationship of circRNA-miRNA-mRNA.

Results

The decreased level of circCDYL was observed in NSCLC patients' tissues and plasma, which was also downregulated in NSCLC cell lines. Forced expression of circCDYL inhibited cell viability, proliferation and induced apoptosis in A549 cells. Luciferase assay verified that circCDYL could bind with miR-185-5p and confirmed that TNRC6A was a downstream target of miR-185-5p. Overexpression of miR-185-5p or silencing of TNRC6A could inhibit the anti-tumor effect of circCDYL in A549 cells via regulating the ERK1/2 signal.

Conclusion

Here, we revealed that circCDYL inhibited proliferation and induced apoptosis in NSCLC cell lines via regulating ERK1/2 signal, and the mechanism of this progression may target miR-185-5p/TNRC6A, which provided a theoretical basis for clinical therapy.

Hsa_circ_0010235 functions as an oncogenic drive in non-small cell lung cancer by modulating miR-433-3p/TIPRL axis

BACKGROUND

Non-small cell lung cancer (NSCLC) is a threat to human health. Circular RNAs (circRNAs) have been proved to function in NSCLC development. In this study, the role of circRNA hsa_circ_0010235 in NSCLC progression and the possible molecular mechanism were explored.

METHODS

Expression of hsa_circ_0010235, miRNA (miR)-433-3p and TOR signaling pathway regulator-like (TIPRL) was examined by quantitative real-time PCR (qRT-PCR). Cell viability and clonogenicity were detected by cell counting kit-8 (CCK-8) assay and colony formation assay, respectively. Flow cytometry was performed to monitor cell apoptosis and cell cycle distribution. Western blot assay was employed to evaluate the protein levels of TIPRL, light chain 3 (LC3)-II/I and p62. Cell metastasis was assessed by Transwell and wound healing assays. The targeted relationship between miR-433-3p and hsa_circ_0010235 or TIPRL was confirmed by dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. Furthermore, the role of hsa_circ_0010235 in vivo was investigated by xenograft assay.

RESULTS

Hsa_circ_0010235 and TIPRL were highly expressed in NSCLC tissues and cells, while miR-433-3p was downregulated. Depletion of hsa_circ_0010235 or gain of miR-433-3p repressed proliferation and autophagy but promoted apoptosis in NSCLC cells. Hsa_circ_0010235 sponged miR-433-3p to upregulate TIPRL expression, so as to affect NSCLC development. Hsa_circ_0010235 knockdown also blocked tumor growth in vivo.

CONCLUSION

Hsa_circ_0010235 knockdown suppressed NSCLC progression by regulating miR-433-3p/TIPRL axis, affording a novel mechanism of NSCLC progression.