Circular RNA hsa_circ_0016070 Is Associated with Pulmonary Arterial Hypertension by Promoting PASMC Proliferation

Pathophysiology of Group 3 Pulmonary Hypertension Associated with Lung Diseases and/or Hypoxia

Pulmonary hypertension associated with lung diseases and/or hypoxia is classified as group 3 in the clinical classification of pulmonary hypertension. The efficacy of existing selective pulmonary vasodilators for group 3 pulmonary hypertension is still unknown, and it is currently associated with a poor prognosis. The mechanisms by which pulmonary hypertension occurs include hypoxic pulmonary vasoconstriction, pulmonary vascular remodeling, a decrease in pulmonary vascular beds, endothelial dysfunction, endothelial-to-mesenchymal transition, mitochondrial dysfunction, oxidative stress, hypoxia-inducible factors (HIFs), inflammation, microRNA, and genetic predisposition. Among these, hypoxic pulmonary vasoconstriction and subsequent pulmonary vascular remodeling are characteristic factors involving the pulmonary vasculature and are the focus of this review. Several factors have been reported to mediate vascular remodeling induced by hypoxic pulmonary vasoconstriction, such as HIF-1α and mechanosensors, including TRP channels. New therapies that target novel molecules, such as mechanoreceptors, to inhibit vascular remodeling are awaited.

Superenhancer-driven circRNA Myst4 involves in pulmonary artery smooth muscle cell ferroptosis in pulmonary hypertension

The abnormal expression of circular RNAs (circRNAs) is emerging as a critical cause in regulation of pathological changes of hypoxic pulmonary hypertension (PH), in which ferroptosis is a new pathological change reported recently. However, how circRNAs regulate ferroptosis remains unclear. Here, we proved a significant decrease in circMyst4 expression in hypoxia. In vitro assays revealed that circMyst4 alleviated hypoxic pulmonary artery smooth muscle cell (PASMC) ferroptosis through directly combing with DDX5 in the nucleus to promote GPX4 mRNA processing and inhibiting the formation of the Eef1a1/ACSL4 complex in the cytoplasm. Additionally, superenhancer (SE) was verified to drive the generation of circMyst4. In vivo assays revealed that circMyst4 inhibited the progression of hypoxic PH. Overall, SE-driven circMyst4 may be a new potential therapeutic target for mediating PASMC ferroptosis through promoting DDX5-regulated GPX4 mRNA processing and inhibiting the binding between Eef1a1 and ACSL4.

RELA-mediated upregulation of LINC03047 promotes ferroptosis in silica-induced pulmonary fibrosis via SLC39A14

Long non-coding RNAs play a key role in silicosis, a fatal fibrotic lung disease, and there is an urgent need to develop new treatment targets. Long intergenic non-protein-coding RNA 3047 (LINC03047) is associated with cancer, but its role and mechanism in the progression of silicosis require further elucidation. This study investigated the function of LINC03047 in the epithelial-mesenchymal transition (EMT) during silicosis progression. LINC03047 expression was upregulated in SiO2-treated BEAS-2B and A549 cells, promoting SiO2-induced ferroptosis and subsequent EMT. Moreover, knockdown of LINC03047 significantly decreased the expression of solute carrier family 39 member 14 (SLC39A14), a ferrous iron transporter, and inhibition of SLC39A14 alleviated the ferroptosis and EMT caused by LINC03047 overexpression. We further investigated that NF-κB p65 (RELA) was critical for LINC03047 transcription in SiO2-treated BEAS-2B and A549 cells. In vivo experiments showed that SLC39A14 deficiency improved SiO2-induced lipid peroxidation and EMT. Collectively, our study reveals the function of the RELA/LINC03047/SLC39A14 axis in SiO2-induced ferroptosis and EMT, thereby contributing to the identification of novel drug targets for silicosis therapy.

Decoding Pulmonary Embolism: Pathophysiology, Diagnosis, and Treatment

Pulmonary Embolism (PE) is a life-threatening condition initiated by the presence of blood clots in the pulmonary arteries, leading to severe morbidity and mortality. Underlying mechanisms involve endothelial dysfunction, including impaired blood flow regulation, a pro-thrombotic state, inflammation, heightened oxidative stress, and altered vascular remodeling. These mechanisms contribute to vascular diseases stemming from PE, such as recurrent thromboembolism, chronic thromboembolic pulmonary hypertension, post-thrombotic syndrome, right heart failure, and cardiogenic shock. Detailing key risk factors and utilizing hemodynamic stability-based categorization, the review aims for precise risk stratification by applying established diagnostic tools and scoring systems. This article explores both conventional and emerging biomarkers as potential diagnostic tools. Additionally, by synthesizing existing knowledge, it provides a comprehensive outlook of the current enhanced PE management and preventive strategies. The conclusion underscores the need for future research to improve diagnostic accuracy and therapeutic effectiveness in PE.

Levosimendan mediates the BMP/Smad axis through upregulation of circUSP34-targeted miR-1298 to alleviate pulmonary hypertension

BACKGROUND

Pulmonary hypertension (PH) is a long-term disease that impacts approximately 1% of the world's population. Currently, levosimendan (Lev) is proposed for PH treatment. However, the mechanism of Lev in the treatment of PH is unknown.

METHODS

We used hypoxia-induced pulmonary artery smooth muscle cells (PASMCs) to establish a PH cell model. A number of cell biology methods were performed to assay alterations in cell proliferation, migration and apoptosis after Lev treatment. qRT-PCR and WB were performed to test the levels of circUSP34 and miR-1298, and BMP/Smad protein respectively. In addition, the regulatory relationship between circUSP34 or BMPR2 with miR-1298 was verified through the use of double luciferase as well as RIP assay. In addition, we explored the regulatory effect of Lev on the circUSP34/miR-1298/BMP/Smad axis using a rat PH model.

RESULTS

Our results demonstrate that Lev inhibited PASMCs cell proliferation, migration and promoted apoptosis exposed to hypoxia. In hypoxia-treated PASMCs, circUSP34 expression got downregulated while miR-1298 upregulated, whereas the addition with Lev resulted in upregulation of circUSP34 expression and downregulation of miR-1298 expression, indicating that circUSP34 can target and regulate miR-1298. In addition, miR-1298 targets and regulates the expression of BMPR2. In a rat PH model induced by hypoxia combined with SU5416, Lev upregulated circUSP34 targeting miR-1298-mediated BMP/Smad axis to alleviate the PH phenotype.

CONCLUSION

We have shown that Lev can be used as a therapeutic drug for PH patients, which works through the circUSP34/miR-1298/BMP/Smad axis to alleviate PH symptoms.

CircRNA-associated ceRNA networks (circCeNETs) in chronic obstructive pulmonary disease (COPD)

Chronic obstructive pulmonary disease (COPD), a chronic airway disorder, which is mostly brought on by cigarette smoke extract (CSE), is a leading cause of death which has a high frequency. In COPD patients, smoking cigarette could also trigger the epithelial-mesenchymal transition (EMT) of airway remodeling. One of the most significant elements of environmental contaminants that is linked to pulmonary damage is fine particulate matter (PM2.5). However, the basic processes of lung injury brought on by environmental contaminants and cigarette smoke are poorly understood, particularly the molecular pathways involved in inflammation. For the clinical management of COPD, investigating the molecular process and identifying workable biomarkers will be important. According to newly available research, circular RNAs (circRNAs) are aberrantly produced and serve as important regulators in the pathological processes of COPD. This class of non-coding RNAs (ncRNAs) functions as microRNA (miRNA) sponges to control the levels of gene expression, changing cellular phenotypes and advancing disease. These findings led us to concentrate our attention in this review on new studies about the regulatory mechanism and potential roles of circRNA-associated ceRNA networks (circCeNETs) in COPD.

Protective effect of the total alkaloid extract from Bulbus Fritillariae Pallidiflorae on cigarette smoke-induced Beas-2B cell injury model and transcriptomic analysis

Background

Bulbus Fritillariae Pallidiflorae (BFP) is a traditional Chinese medicine that has long been used to treat lung diseases, but the active components and mechanism are still unclear.

Objective

This study aimed to investigate the effect and mechanism of the total alkaloid extract from BFP (BFP-TA) on cigarette smoke extract (CSE)-induced Beas-2B cells injury.

Design

The Beas-2B cells injury model was induced by 2% CSE, then the effect of BFP-TA on the levels of total antioxidant capacity (T-AOC), superoxide dismutase (SOD) and malondialdehyde (MDA) was detected according to the instructions of the T-AOC assay kit, the SOD detection kit and the MDA detection kit, and the production of ROS was detected by fluorescence microscopy. The effect of BFP-TA on Beas-2B cells apoptosis was detected by flow cytometry, and the effect of BFP-TA on related protein expression was detected by western blot. Subsequently, the effect of BFP-TA on differentially expressed genes (DEGs) in CSE-induced Beas-2B cells was studied by transcriptomic sequencing, and the expression of DEGs was verified by quantitative real-time polymerase chain reaction (qPCR).

Results

The results showed that BFP-TA could attenuate CSE-induced oxidative damage in Beas-2B cells by elevating T-AOC and SOD levels while inhibiting ROS and MDA levels, and the mechanism was potentially related to the SIRT1/Nrf2/Keap1 signaling pathway. Furthermore, BFP-TA could inhibit CSE-induced apoptosis by inhibiting the protein expression of Bax, MST1 and FOXO3a, and exert anti-inflammatory effect by inhibiting the activation of MAPK signaling pathway. Subsequently, transcriptome analysis and qPCR validation showed that BFP-TA could alleviate inflammation, oxidative stress, apoptosis and lipid metabolism disorders by regulating the expression of DEGs in PPAR and PI3K-Akt signaling pathways, thereby exerting a protective effect against CSE-induced Beas-2B cell injury.

Conclusion

This study is the first to demonstrate that BFP-TA could exert a protective effect on CSE-induced Beas-2B cell injury by exerting anti-inflammatory, antioxidant, anti-apoptotic and regulate lipid metabolism disorders.

CircPMS1 promotes proliferation of pulmonary artery smooth muscle cells, pulmonary microvascular endothelial cells, and pericytes under hypoxia

BACKGROUND

Circular RNAs (circRNAs) have been recognized as significant regulators of pulmonary hypertension (PH); however, the differential expression and function of circRNAs in different vascular cells under hypoxia remain unknown. Here, we identified co-differentially expressed circRNAs and determined their putative roles in the proliferation of pulmonary artery smooth muscle cells (PASMCs), pulmonary microvascular endothelial cells (PMECs), and pericytes (PCs) under hypoxia.

METHODS

Whole transcriptome sequencing was performed to analyze the differential expression of circRNAs in three different vascular cell types. Bioinformatic analysis was used to predict their putative biological function. Quantitative real-time polymerase chain reaction, Cell Counting Kit-8, and EdU Cell Proliferation assays were carried out to determine the role of circular postmeiotic segregation 1 (circPMS1) as well as its potential sponge mechanism in PASMCs, PMECs, and PCs.

RESULTS

PASMCs, PMECs, and PCs exhibited 16, 99, and 31 differentially expressed circRNAs under hypoxia, respectively. CircPMS1 was upregulated in PASMCs, PMECs, and PCs under hypoxia and enhanced the proliferation of vascular cells. CircPMS1 may upregulate DEP domain containing 1 (DEPDC1) and RNA polymerase II subunit D expression by targeting microRNA-432-5p (miR-432-5p) in PASMCs, upregulate MAX interactor 1 (MXI1) expression by targeting miR-433-3p in PMECs, and upregulate zinc finger AN1-type containing 5 (ZFAND5) expression by targeting miR-3613-5p in PCs.

CONCLUSIONS

Our results suggest that circPMS1 promotes cell proliferation through the miR-432-5p/DEPDC1 or miR-432-5p/POL2D axis in PASMCs, through the miR-433-3p/MXI1 axis in PMECs, and through the miR-3613-5p/ZFAND5 axis in PCs, which provides putative targets for the early diagnosis and treatment of PH.

RNA m6A methylation and regulatory proteins in pulmonary arterial hypertension

m6A (N6‑methyladenosine) is the most common and abundant apparent modification in mRNA of eukaryotes. The modification of m6A is regulated dynamically and reversibly by methyltransferase (writer), demethylase (eraser), and binding protein (reader). It plays a significant role in various processes of mRNA metabolism, including regulation of transcription, maturation, translation, degradation, and stability. Pulmonary arterial hypertension (PAH) is a malignant cardiopulmonary vascular disease characterized by abnormal proliferation of pulmonary artery smooth muscle cells. Despite the existence of several effective and targeted therapies, there is currently no cure for PAH and the prognosis remains poor. Recent studies have highlighted the crucial role of m6A modification in cardiovascular diseases. Investigating the role of RNA m6A methylation in PAH could provide valuable insights for drug development. This review aims to explore the mechanism and function of m6A in the pathogenesis of PAH and discuss the potential targeting of RNA m6A methylation modification as a treatment for PAH.

Hsa_circ_0008833 promotes COPD progression via inducing pyroptosis in bronchial epithelial cells

Purpose: Chronic obstructive pulmonary disease (COPD) is a common respiratory disorder. Pyroptosis represents a distinctive form of inflammatory cell death that is mediated through the activation of Caspase-1 and inflammasomes. CircRNAs have emerged as a novel class of biomolecules with implications in various human diseases. This study aims to investigate the circRNAs profile of in COPD progression and identify pivotal circRNAs associated with the development of this disease. Methods: he expression profiles of circRNAs in peripheral blood mononuclear cells of COPD patients were assessed by circRNA microarray. Furthermore, flag-labeled vectors were constructed to assess the potential protein-coding capacity of has-circ-0008833. 16HBE cells were stably transfected with lentivirus approach, and cell proliferation and death were assessed to clarify the functional roles of has-circ-0008833 and its encoded protein circ-0008833aa. Additionally, western blot analysis was furthered performed to determine the level of Caspase-1, IL-18, IL-1β, NLRP3, ASC, and cleaved GSDMD regulated by has-circ-0008833 and circ-0008833-57aa. Results: Initially, we screened the expression profiles of human circRNAs in peripheral blood mononuclear cells of COPD patients, and found that has-circ-0008833 exhibited a significant increase in COPD mononuclear cells. Subsequently, we demonstrated that has-circ-0008833 carried an open reading frame (ORF), which encoded a functional protein, referred to as circ-0008833-57aa. By employing gain-of-function approaches, our results suggested that both circ-0008833 and circ-0008833-57aa inhibited proliferation, but accelerated the rate of 16HBE cell death. Finally, we discovered that circ-0008833 and circ-0008833-57aa promoted the expression of Caspase-1, IL-18, IL-1β, NLRP3, ASC, and cleaved GSDMD in 16HBE cells. Conclusions: Upregulation of circ-0008833 might promote COPD progression by inducing pyroptosis of bronchial epithelial cells through the encoding of a 57-amino acid peptide.

MicroRNAs and their regulators: Potential therapeutic targets in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a complex and progressive disease characterized by pulmonary arterial remodeling. Despite that current combination therapy has shown improvement in morbidity and mortality, a better deciphering of the underlying pathological mechanisms and novel therapeutic targets is urgently needed to combat PAH. MicroRNA, the critical element in post-transcription mechanisms, mediates cellular functions mainly by tuning downstream target gene expression. Meanwhile, upstream regulators can regulate miRNAs in synthesis, transcription, and function. In vivo and in vitro studies have suggested that miRNAs and their regulators are involved in PAH. However, the miRNA-related regulatory mechanisms governing pulmonary vascular remodeling and right ventricular dysfunction remain elusive. Hence, this review summarized the controversial roles of miRNAs in PAH pathogenesis, focused on different miRNA-upstream regulators, including transcription factors, regulatory networks, and environmental stimuli, and finally proposed the prospects and challenges for the therapeutic application of miRNAs and their regulators in PAH treatment.

Identification of circRNA-associated ceRNA networks in peripheral blood mononuclear cells as potential biomarkers for chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD), which is a common respiratory disorder with high morbidity and mortality globally, has a complex pathogenesis that is not fully understood. Some circular RNAs (circRNAs) have been recognized to serve as miRNA sponges for regulating target RNA transcripts during the processes of human diseases. In the present study, we aimed to investigate novel circRNA-associated biomarkers for COPD, 245 differentially expressed circRNAs were identified, including 111 up-regulated and 134 down-regulated circRNAs. These candidate circRNAs were enriched in inflammation-associated pathways (such as mTOR, B-cell receptor, and NF-κB signaling pathways) via Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses. A combination of two circRNAs (up-regulated hsa_circ_0067209 and down-regulated hsa_circ_0000673) demonstrated good diagnostic value (area under the receiver operating characteristic curve [AUC] = 0.866) for COPD by receiver operating characteristic curve (ROC) analysis and qRT-PCR validation. Subsequently, hsa-miR-8082 and hsa-miR-1248 were identified as targets for hsa_circ_0067209 and hsa_circ_0000673, respectively, via bioinformatics analysis and a dual-luciferase reporter assay, and the combination of these two miRNAs displayed better diagnosis potential for COPD (AUC = 0.967) than each other. Evaluation of COPD-related mRNA profiles revealed that the up-regulated genes ABR and TRPM6 were predicted downstream targets for hsa_circ_0067209/hsa-miR-8082, whereas the down-regulated gene RORC was a predicted downstream target for hsa_circ_0000673/hsa-miR-1248. In summary, hsa_circ_0067209 and hsa_circ_0000673 have potential as novel diagnostic biomarkers of COPD. In addition, competing endogenous RNA networks of hsa_circ_0067209/hsa-miR-8082/ABR/TRPM6 and hsa_circ_0000673/hsa-miR-1248/RORC may play critical regulation roles for COPD pathogenesis.

The vascular perspective on acute and chronic lung disease

The pulmonary vasculature has been frequently overlooked in acute and chronic lung diseases, such as acute respiratory distress syndrome (ARDS), pulmonary fibrosis (PF), and chronic obstructive pulmonary disease (COPD). The primary emphasis in the management of these parenchymal disorders has largely revolved around the injury and aberrant repair of epithelial cells. However, there is increasing evidence that the vascular endothelium plays an active role in the development of acute and chronic lung diseases. The endothelial cell network in the capillary bed and the arterial and venous vessels provides a metabolically highly active barrier that controls the migration of immune cells, regulates vascular tone and permeability, and participates in the remodeling processes. Phenotypically and functionally altered endothelial cells, and remodeled vessels, can be found in acute and chronic lung diseases, although to different degrees, likely because of disease-specific mechanisms. Since vascular remodeling is associated with pulmonary hypertension, which worsens patient outcomes and survival, it is crucial to understand the underlying vascular alterations. In this Review, we describe the current knowledge regarding the role of the pulmonary vasculature in the development and progression of ARDS, PF, and COPD; we also outline future research directions with the hope of facilitating the development of mechanism-based therapies.

Molecular regulation and therapeutic implications of cell death in pulmonary hypertension

Pulmonary hypertension (PH) is a clinical and pathophysiological syndrome caused by changes in pulmonary vascular structure or function that results in increased pulmonary vascular resistance and pulmonary arterial pressure, and it is characterized by pulmonary endothelial dysfunction, pulmonary artery media thickening, pulmonary vascular remodeling, and right ventricular hypertrophy, all of which are driven by an imbalance between the growth and death of pulmonary vascular cells. Programmed cell death (PCD), different from cell necrosis, is an active cellular death mechanism that is activated in response to both internal and external factors and is precisely regulated by cells. More than a dozen PCD modes have been identified, among which apoptosis, autophagy, pyroptosis, ferroptosis, necroptosis, and cuproptosis have been proven to be involved in the pathophysiology of PH to varying degrees. This article provides a summary of the regulatory patterns of different PCD modes and their potential effects on PH. Additionally, it describes the current understanding of this complex and interconnected process and analyzes the therapeutic potential of targeting specific PCD modes as molecular targets.

circNFXL1 Modulates the Kv2.1 Channel Function in Hypoxic Human Pulmonary Artery Smooth Muscle Cells via Sponging miR-29b-2-5p as a Competitive Endogenous RNA

ABSTRACT

Pulmonary arterial hypertension is characterized by abnormal pulmonary vasoconstriction and vascular remodeling caused by the dysregulation of K + channels in PA smooth muscle cells (PASMCs). However, how the K + channels are dysregulated is still unclear. Circular RNAs (circRNAs) are noncoding RNAs with a closed-loop structure capable of sponging microRNAs (miRs), thus regulating gene expression at the post-transcriptional level. Our previous studies have demonstrated the importance of one novel circRNA (hsa_circNFXL1_009, circNFXL1) in pulmonary arterial hypertension patients, playing as a critical regulator for K + channel activation in hypoxic human PASMCs (hPASMCs). Here, we explore the mechanisms underlying circNFXL1-regulated K + channel expression and functions in hypoxic hPASMCs. In cultured hPASMCs, the reduction of Kv current induced by hypoxia was significantly recovered by delivering exogenous circNFXL1. Moreover, luciferase, quantitative reverse transcription-quantitative polymerase chain reaction, western blot, and mutagenesis studies confirmed that circNFXL1 reversed hypoxia-induced inhibitory effects on the Kv2.1 channel via sponging hsa-miR-29b-2-5p (miR-29b-2). Furthermore, we found that circNFXL1 reversed the miR-29b-induced Kv2.1 channel dysfunction at the whole-cell and single-channel level in HEK cells using a patch-clamp. Finally, calcium imaging revealed that hypoxia also triggered a substantial rise in the cytosolic calcium concentration ([Ca2 + ]cyt) in hPASMCs, and this hypoxia-induced elevation of [Ca2 + ]cyt was reduced by circNFXL1 through miR-29b-2. These data suggested that circNFXL1-mediated regulation of the Kv2.1 channel activation and the related intracellular calcium concentration may contribute to the effects of hypoxic pulmonary vasoconstriction.

Pulmonary arterial hypertension associated with congenital heart disease: An omics study

Pulmonary arterial hypertension associated with congenital heart disease (PAH-CHD) is a severely progressive condition with uncertain physiological course. Hence, it has become increasingly relevant to clarify the specific mechanisms of molecular modification, which is crucial to identify more treatment strategies. With the rapid development of high-throughput sequencing, omics technology gives access to massive experimental data and advanced techniques for systems biology, permitting comprehensive assessment of disease occurrence and progression. In recent years, significant progress has been made in the study of PAH-CHD and omics. To provide a comprehensive description and promote further in-depth investigation of PAH-CHD, this review attempts to summarize the latest developments in genomics, transcriptomics, epigenomics, proteomics, metabolomics, and multi-omics integration.

circ-BPTF serves as a miR-486-5p sponge to regulate CEMIP and promotes hypoxic pulmonary arterial smooth muscle cell proliferation in COPD

Hypoxia plays a crucial role in pulmonary vascular remodelling at the early stage of chronic obstructive pulmonary disease (COPD). Circle RNA (circRNA) has been identified to play a critical role in multiple diseases. However, the role of circRNAs in pulmonary vascular remodelling in COPD remains unclear. In this study, we aim to investigate the role of circRNAs in pulmonary arterial smooth muscle cell proliferation and pulmonary vascular remodelling in COPD. COPD patients show lower partial pressure of arterial oxygen and pulmonary arterial remodeling as compared with controls. circRNA microarray and real-time PCR analyses show significantly higher level of circ-BPTF and lower miR-486-5p level in the pulmonary arteries of COPD patients as compared with controls. Hypoxia suppresses miR-486-5p expression but promotes expressions of circ-BPTF and cell migration inducing protein (CEMIP) in human pulmonary arterial smooth muscle cells (PASMCs) in vitro. Loss- and gain-of-function experiments show that circ-BPTF promotes PASMC proliferation in vitro. Moreover, luciferase reporter assay results indicate that circ-BPTF regulates PASMC proliferation by acting as an miR-486-5p sponge. CEMIP is identified as a candidate target gene of miR-486-5p by luciferase reporter assay. Overall, our study shows that circ-BPTF serves as a miR-486-5p sponge to regulate CEMIP and promote hypoxic PASMC proliferation in pulmonary vascular remodelling in COPD.

The role of circular RNAs in pulmonary hypertension

Circular RNAs (circRNAs) are endogenous, covalently circularised, non-protein-coding RNAs generated from back-splicing. Most circRNAs are very stable, highly conserved, and expressed in a tissue-, cell- and developmental stage-specific manner. circRNAs play a significant role in various biological processes, such as regulation of gene expression and protein translation via sponging of microRNAs and binding with RNA-binding proteins. circRNAs have become a topic of great interest in research due to their close link with the development of various diseases. Their high stability, conservation and abundance in body fluids make them promising biomarkers for many diseases. A growing body of evidence suggests that aberrant expression of circRNAs and their targets plays a crucial role in pulmonary vascular remodelling and pulmonary arterial hypertension (group 1) as well as other forms (groups 3 and 4) of pulmonary hypertension (PH). Here we discuss the roles and molecular mechanisms of circRNAs in the pathogenesis of pulmonary vascular remodelling and PH. We also highlight the therapeutic and biomarker potential of circRNAs in PH.

CircGSAP alleviates pulmonary microvascular endothelial cells dysfunction in pulmonary hypertension via regulating miR-27a-3p/BMPR2 axis

Background

Our previous study showed that circular RNA-gamma-secretase-activating protein (circGSAP) was down-regulated in pulmonary microvascular endothelial cells (PMECs) in response to hypoxia, and regulated the cell cycle of PMECs via miR-942-5p sponge in pulmonary hypertension (PH). However, the mechanism whether circGSAP affects the dysfunction of PEMCs through other microRNAs (miRNAs) remains largely unknown. Therefore, we aimed to demonstrate the underlying mechanisms of circGSAP regulating PMECs dysfunction by absorbing other miRNAs to regulate target genes in idiopathic pulmonary arterial hypertension (IPAH).

Methods

Quantitative real-time polymerase chain reaction, immunofluorescence staining, Cell Counting Kit-8, Calcein-AM/PI staining, Transwell assay, dual-luciferase reporter assay, and ELISA were used to elucidate the roles of circGSAP.

Results

Here we showed that plasma circGSAP levels were significantly decreased in patients with IPAH and associated with poor outcomes. In vivo, circGSAP overexpression improved survival, and alleviated pulmonary vascular remodeling of monocrotaline-induced PH (MCT-PH) rats. In vitro, circGSAP overexpression inhibited hypoxia-induced PMECs proliferation, migration and increased mortality by absorbing miR-27a-3p. BMPR2 was identified as a miR-27a-3p target gene. BMPR2 silencing ameliorated the effect of the miR-27a-3p inhibitor on PMECs proliferation,migration and mortality. The levels of BMPR2 were upregulated in circGSAP-overexpressed PMECs and lung tissues of MCT-PH rats.

Conclusion

Our findings demonstrated that circGSAP alleviated the dysfunction of PMECs via the increase of BMPR2 by competitively binding with miR-27a-3p, and mitigated pulmonary vascular remodeling of MCT-PH rats, providing potential therapeutic strategies for IPAH.

Circular RNAs Regulate Vascular Remodelling in Pulmonary Hypertension

Circular RNAs (circRNAs) are a newly identified type of noncoding RNA molecule with a unique closed-loop structure. circRNAs are widely expressed in different tissues and developmental stages of many species, participating in many important pathophysiological processes and playing an important role in the occurrence and development of diseases. This article reviews the discovery, characteristics, formation, and biological function of circRNAs. The relationship between circRNAs and vascular remodelling, as well as the current status of research and potential application value in pulmonary hypertension (PH), is discussed to promote a better understanding of the role of circRNAs in PH. circRNAs are closely related to the remodelling of vascular endothelial cells and vascular smooth muscle cells. circRNAs have potential application prospects for in-depth research on the possible pathogenesis and mechanism of PH. Future research on the role of circRNAs in the pathogenesis and mechanism of PH will provide new insights and promote screening, diagnosis, prevention, and treatment of this disease.

Reduced CircSMOC1 Level Promotes Metabolic Reprogramming via PTBP1 (Polypyrimidine Tract-Binding Protein) and miR-329-3p in Pulmonary Arterial Hypertension Rats

BACKGROUND

Pulmonary arterial hypertension maintains rapid cell proliferation and vascular remodeling through metabolic reprogramming. Recent studies suggested that circRNAs play important role in pulmonary vascular remodeling and pulmonary arterial smooth muscle cells proliferation. However, the relationship between circRNA, cell proliferation, and metabolic reprogramming in pulmonary arterial hypertension has not been investigated.

METHODS

RNA-seq and qRT-PCR reveal the differential expression profile of circRNA in pulmonary arteries of pulmonary arterial hypertension rat models. Transfection was used to examine the effects of circSMOC1 on pulmonary artery smooth muscle cells, and the roles of circSMOC1 in vivo were investigated by adenoassociated virus. Mass spectrometry, RNA pull-down, RNA immunoprecipitation, and dual-luciferase reporter assay were performed to investigate the signaling pathway of circSMOC1 regulating the metabolic reprogramming.

RESULTS

CircSMOC1 was significantly downregulated in pulmonary arteries of pulmonary arterial hypertension rats. CircSMOC1 knockdown promoted proliferation and migration and enhanced aerobic glycolysis of pulmonary artery smooth muscle cells. CircSMOC1 overexpression in vivo alleviates pulmonary vascular remodeling, right ventricular pressure, and right heart hypertrophy. In the nucleus, circSMOC1 directly binds to PTBP1 (polypyrimidine tract-binding protein), competitively inhibits the specific splicing of PKM (pyruvate kinase M) premRNA, resulting in the upregulation of PKM2 (pyruvate kinase M2), the key enzyme of aerobic glycolysis, to enhance glycolysis. In the cytoplasm, circSMOC1 acted as a miR-329-3p sponge, and its reduction in pulmonary arterial hypertension suppressed PDHB (pyruvate dehydrogenase E1 subunit beta) expression, leading to the impairment of mitochondrial oxidative phosphorylation.

CONCLUSIONS

circSMOC1 is crucially involved in the metabolic reprogramming of pulmonary artery smooth muscle cells through PTBP1 and miR-329-3p to regulate pulmonary vascular remodeling in pulmonary arterial hypertension.

Clinical value of lncRNA SOX2-OT in pulmonary arterial hypertension and its role in pulmonary artery smooth muscle cell proliferation, migration, apoptosis, and inflammatory

BACKGROUND

Non-coding RNA is confirmed to be involved in pulmonary arterial hypertension (PAH).

OBJECTIVES

This study investigated the clinical value and potential mechanisms of the long noncoding RNA (lncRNA) SRY-box transcription factor 2 overlapping transcript (SOX2-OT) in PAH.

METHODS

SOX2-OT levels were measured by quantitative real-time polymerase chain reaction (qRT-PCR) in serum of 82 patients with PAH and 76 healthy controls. Receiver operating characteristic (ROC) analysis was performed to assess the diagnostic value of SOX2-OT. Human pulmonary arterial smooth muscle cells (hPASMCs) were treated by hypoxia to construct PAH cell models. Proliferation, migration, apoptosis, and inflammatory cytokines levels of hPASMCs were examined by CCK-8, Transwell, flow cytometry, and ELISA assay. Dual-luciferase reporter gene assays were performed to verify the target relationships between miR-455-3p and SOX2-OT, as well as small ubiquitin-related modifier 1 (SUMO1).

RESULTS

Serum SOX2-OT was highly expressed in patients with PAH (P < 0.05). And elevated SOX2-OT levels significantly differentiated PAH patients from healthy controls, confirming high diagnostic feasibility. What's more, SOX2-OT was increased in hypoxia-induced hPASMCs in a time-dependent manner. Silencing SOX2-OT could reverse hypoxia-induced proliferation, migration, anti-apoptosis, and inflammation of hPASMCs (P < 0.05). However, rescue experiments showed that this reversal effect of silencing SOX2-OT was attenuated by suppressed miR-455-3p, which was presumably achieved by SUMO1 (P < 0.05).

CONCLUSIONS

Elevated SOX2-OT is a feasible diagnostic marker for PAH, and its silencing may attenuated hypoxia-induced hPASMCs proliferation, migration, anti-apoptosis, and inflammation by modulating the miR-455-3p/SUMO1 axis, preventing vascular remodeling and PAH progression. Our research provided new insights for PAH treatment.

Hsa_circ_0016070/micro‐340‐5p Axis Accelerates Pulmonary Arterial Hypertension Progression by Upregulating TWIST1 Transcription Via TCF4/β‐Catenin Complex

Background

Hypoxia is considered a major leading cause of pulmonary hypertension (PH). In this study, the roles and molecular mechanism of circ_0016070 in PH were studied.

Methods and Results

The expression of circ_0016070 in serum samples, human pulmonary artery smooth muscle cells and hypoxia/monocrotaline‐treated rats was determined by real‐time quantitative polymerase chain reaction. Cell viability, migration, and apoptosis were analyzed by Cell Counting Kit‐8, wound healing, flow cytometry, and TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) assays, respectively. The molecular interactions were validated using RNA immunoprecipitation, chromatin immunoprecipitation, and dual luciferase reporter assays. The levels of phenotype switch‐related proteins were evaluated by Western blot and immunohistochemistry. The pathological characteristics were assessed using hematoxylin and eosin staining. circ_0016070 was highly expressed in the serum samples, hypoxia‐induced pulmonary artery smooth muscle cells and pulmonary arterial tissues of PH rats. Downregulation of circ_0016070 ameliorated the excessive proliferation, migration, vascular remodeling, and phenotypic transformation but enhanced cell apoptosis in the PH rat model. In addition, micro (miR)‐340‐5p was verified as a direct target of circ_0016070 and negatively regulated TCF4 (transcription factor 4) expression. TCF4 formed a transcriptional complex with β‐catenin to activate TWIST1 (Twist family bHLH transcription factor 1) expression. Functional rescue experiments showed that neither miR‐340‐5p inhibition nor TWIST1 or TCF4 upregulation significantly impeded the biological roles of circ_0010670 silencing in PH.

Conclusions

These results uncovered a novel mechanism by which circ_0016070 play as a competing endogenouse RNA of miR‐340‐5p to aggravate PH progression by promoting TCF4/β‐catenin/TWIST1 complex, which may provide potential therapeutic targets for PH.

Comprehensive identification of RNA transcripts and construction of RNA network in chronic obstructive pulmonary disease

Background

Chronic obstructive pulmonary disease (COPD) is one of the world’s leading causes of death and a major chronic disease, highly prevalent in the aging population exposed to tobacco smoke and airborne pollutants, which calls for early and useful biomolecular predictors. Roles of noncoding RNAs in COPD have been proposed, however, not many studies have systematically investigated the crosstalk among various transcripts in this context. The construction of RNA functional networks such as lncRNA-mRNA, and circRNA-miRNA-mRNA interaction networks could therefore facilitate our understanding of RNA interactions in COPD. Here, we identified the expression of RNA transcripts in RNA sequencing from COPD patients, and the potential RNA networks were further constructed.

Methods

All fresh peripheral blood samples of three patients with COPD and three non-COPD patients were collected and examined for mRNA, miRNA, lncRNA, and circRNA expression followed by qRT-PCR validation. We also examined mRNA expression to enrich relevant biological pathways. lncRNA-mRNA coexpression network and circRNA-miRNA-mRNA network in COPD were constructed.

Results

In this study, we have comprehensively identified and analyzed the differentially expressed mRNAs, lncRNAs, miRNAs, and circRNAs in peripheral blood of COPD patients with high-throughput RNA sequencing. 282 mRNAs, 146 lncRNAs, 85 miRNAs, and 81 circRNAs were differentially expressed. GSEA analysis showed that these differentially expressed RNAs correlate with several critical biological processes such as “ncRNA metabolic process”, “ncRNA processing”, “ribosome biogenesis”, “rRNAs metabolic process”, “tRNA metabolic process” and “tRNA processing”, which might be participating in the progression of COPD. RT-qPCR with more clinical COPD samples was used for the validation of some differentially expressed RNAs, and the results were in high accordance with the RNA sequencing. Given the putative regulatory function of lncRNAs and circRNAs, we have constructed the co-expression network between lncRNA and mRNA. To demonstrate the potential interactions between circRNAs and miRNAs, we have also constructed a competing endogenous RNA (ceRNA) network of differential expression circRNA-miRNA-mRNA in COPD.

Conclusions

In this study, we have identified and analyzed the differentially expressed mRNAs, lncRNAs, miRNAs, and circRNAs, providing a systematic view of the differentially expressed RNA in the context of COPD. We have also constructed the lncRNA-mRNA co-expression network, and for the first time constructed the circRNA-miRNA-mRNA in COPD. This study reveals the RNA involvement and potential regulatory roles in COPD, and further uncovers the interactions among those RNAs, which will assist the pathological investigations of COPD and shed light on therapeutic targets exploration for COPD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02069-8.

The Landscape of Noncoding RNA in Pulmonary Hypertension

The transcriptome of pulmonary hypertension (PH) is complex and highly genetically heterogeneous, with noncoding RNA transcripts playing crucial roles. The majority of RNAs in the noncoding transcriptome are long noncoding RNAs (lncRNAs) with less circular RNAs (circRNAs), which are two characteristics gaining increasing attention in the forefront of RNA research field. These noncoding transcripts (especially lncRNAs and circRNAs) exert important regulatory functions in PH and emerge as potential disease biomarkers and therapeutic targets. Recent technological advancements have established great momentum for discovery and functional characterization of ncRNAs, which include broad transcriptome sequencing such as bulk RNA-sequence, single-cell and spatial transcriptomics, and RNA-protein/RNA interactions. In this review, we summarize the current research on the classification, biogenesis, and the biological functions and molecular mechanisms of these noncoding RNAs (ncRNAs) involved in the pulmonary vascular remodeling in PH. Furthermore, we highlight the utility and challenges of using these ncRNAs as biomarkers and therapeutics in PH.

Bioinformatic analysis of dysregulated circular RNAs in pediatric pulmonary hypertension linked congenital heart disease

BACKGROUND

Circular RNAs (circRNAs) may play important roles in the progression of pulmonary arterial hypertension. However, the potential roles they play in childhood pulmonary arterial hypertension associated congenital heart disease (CHD) progression remains unclear.

METHODS

Thirteen human plasma samples including eight from pulmonary arterial hypertension secondary to CHD patients and five from a control group were analyzed using the Arraystar Human circRNA array. The relative expression levels of five differentially expressed circRNAs in pulmonary arterial hypertension were detected using real-time polymerase chain reaction (PCR) analysis. In parallel, these levels were also taken on control samples from 32 CHD patients. We used miRanda and TargetScan software packages to predict potential microRNA (miRNA)targets, which were then combined into a circRNA-miRNA-messenger RNA (mRNA) network.

RESULTS

Twenty-seven circRNAs (three upregulated and 24 downregulated) were differentially expressed between the pulmonary arterial hypertension and control groups. Compared to control group levels, circ_003416 expression in the pulmonary arterial hypertension group was significantly downregulated, while circ_005372 expression, in contrast, was significantly upregulated. The differential expression of these circRNAs was mainly linked to variation in levels of oxidative phosphorylation and tight junction signaling.

CONCLUSIONS

We identified one overexpressed and one underexpressed circRNA in plasma samples from children with CHD associated pulmonary arterial hypertension. Bioinformatic analysis indicated these dysregulated circRNAs might be associated with the occurrence and regulation of pulmonary arterial hypertension.

Expression and clinical significance of circular RNA hsa_circ_0003416 in pediatric pulmonary arterial hypertension associated with congenital heart disease

Background

Circular RNAs (circRNAs) have been found to be involved in the development of pulmonary arterial hypertension (PAH). However, their diagnostic value in pediatric PAH remains unclear. This study aimed to examine the characteristic expression of the circRNA hsa_circ_0003416 in the plasma of children with PAH caused by congenital heart disease (CHD); the potential of hsa_circ_0003416 as a diagnostic biomarker was also investigated.

Methods

The plasma expression levels of hsa_circ_0003416 were determined via quantitative reverse transcription–polymerase chain reaction in 50 CHD patients, 50 PAH patients, and 20 healthy subjects; the associations between hsa_circ_0003416 levels and clinical data were analyzed thereafter. Receiver operating characteristic curves were employed to determine the diagnostic capacity of this circRNA.

Results

Expression levels of hsa_circ_0003416 in plasma were lower in the PAH‐CHD group than in the CHD and healthy control groups (p = 0.009 vs. healthy control group, p = 0.026 vs. CHD group). Moreover, hsa_circ_0003416 was found to be negatively associated with B‐type natriuretic peptide (r = −0.342, p = 0.013). In addition, the area under the curve of hsa_circ_0003416 levels in plasma was 0.721 (95% confidence intervals = 0.585–0.857, p = 0.004), suggesting that it has a promising diagnostic value.

Conclusions

Overall, hsa_circ_0003416 was found to be significantly downregulated in children with PAH‐CHD and to be potent as a biomarker for PAH‐CHD diagnosis.

CircRNA circ_0006892 regulates miR-24/PHLPP2 axis to mitigate cigarette smoke extract-induced bronchial epithelial cell injury

Chronic obstructive pulmonary disease (COPD) is a chronic airway disorder mainly resulted from cigarette smoke exposure. The dysregulated circular RNAs (circRNAs) are relevant to the pathogenesis of COPD. This study aims to explore the function and mechanism of circRNA hsa_circ_0006892 (circ_0006892) in cigarette smoke extract (CSE)-induced bronchial epithelial injury. The lung tissues were collected from 17 nonsmokers and 23 smokers with COPD. The bronchial epithelial cells (BEAS-2B and 16HBE) were stimulated via CSE. Circ_0006892, microRNA-24 (miR-24), and PH domain and leucine-rich repeat protein phosphatase 2 (PHLPP2) abundances were examined via a quantitative reverse transcription polymerase chain reaction or Western blot. Cell viability, apoptosis, and inflammatory response were assessed via cell counting kit-8 (CCK-8), flow cytometry, and enzyme-linked immunosorbent assay (ELISA). The target relationship of miR-24 and circ_0006892 or PHLPP2 was tested via dual-luciferase reporter analysis, RNA immunoprecipitation, and RNA pull-down. Circ_0006892 expression was reduced in lung tissues of smokers with COPD and CSE-stimulated bronchial epithelial cells. Circ_0006892 overexpression alleviated CSE-induced viability reduction and promotion of apoptosis and inflammatory response. MiR-24 was bound via circ_0006892, and miR-24 overexpression reversed the effect of circ_0006892 on CSE-induced injury. PHLPP2 was targeted via miR-24, and miR-24 knockdown mitigated CSE-induced viability reduction and promotion of apoptosis and inflammatory response via regulating PHLPP2. Circ_0006892 could promote PHLPP2 expression via regulating miR-24. Circ_0006892 attenuated CSE-induced bronchial epithelial cell apoptosis and inflammatory response via regulating miR-24/PHLPP2 axis.

Decoding ceRNA regulatory network in the pulmonary artery of hypoxia-induced pulmonary hypertension (HPH) rat model

Background

Hypoxia-induced pulmonary hypertension (HPH) is a lethal cardiovascular disease with the characteristic of severe remodeling of pulmonary vascular. Although a large number of dysregulated mRNAs, lncRNAs, circRNAs, and miRNAs related to HPH have been identified from extensive studies, the competitive endogenous RNA (ceRNA) regulatory network in the pulmonary artery that responds to hypoxia remains largely unknown.

Results

Transcriptomic profiles in the pulmonary arteries of HPH rats were characterized through high-throughput RNA sequencing in this study. Through relatively strict screening, a set of differentially expressed RNAs (DERNAs) including 19 DEmRNAs, 8 DElncRNAs, 19 DEcircRNAs, and 23 DEmiRNAs were identified between HPH and normal rats. The DEmRNAs were further found to be involved in cell adhesion, axon guidance, PPAR signaling pathway, and calcium signaling pathway, suggesting their crucial role in HPH. Moreover, a hypoxia-induced ceRNA regulatory network in the pulmonary arteries of HPH rats was constructed according to the ceRNA hypothesis. More specifically, the ceRNA network was composed of 10 miRNAs as hub nodes, which might be sponged by 6 circRNAs and 7 lncRNAs, and directed the expression of 18 downstream target genes that might play important role in the progression of HPH. The expression patterns of selected DERNAs in the ceRNA network were then validated to be consistent with sequencing results in another three independent batches of HPH and normal control rats. The diagnostic effectiveness of several hub mRNAs in ceRNA network was further evaluated through investigating their expression profiles in patients with pulmonary artery hypertension (PAH) recorded in the Gene Expression Omnibus (GEO) dataset GSE117261. Dysregulated POSTN, LTBP2, SPP1, and LSAMP were observed in both the pulmonary arteries of HPH rats and lung tissues of PAH patients.

Conclusions

A ceRNA regulatory network in the pulmonary arteries of HPH rats was constructed, 10 hub miRNAs and their corresponding interacting lncRNAs, circRNAs, and mRNAs were identified. The expression patterns of selected DERNAs were further validated to be consistent with the sequencing result. POSTN, LTBP2, SPP1, and LSAMP were suggested to be potential diagnostic biomarkers and therapeutic targets for PAH.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-022-00762-1.

Circular RNAs in pulmonary hypertension: Emerging biological concepts and potential mechanism

Circular RNAs (circRNAs) are endogenous RNAs with a covalently closed single-stranded transcript. They are a novel class of genomic regulators that are linked to many important development and disease processes and are being pursued as clinical and therapeutic targets. Using the most powerful RNA sequencing and bioinformatics techniques, a large number of circRNAs have been identified and further functional studies have been performed. It is known that circRNAs act as potential biomarkers, sponges for microRNAs (miRNAs) and RNA-binding proteins (RBPs), and regulators of mRNA transcription. They also participate in the translation of peptides or proteins. Many types of circRNAs are dysregulated in plasma or lung tissues, and they may be involved in regulating the proliferation and apoptosis of pulmonary artery endothelial cells (PAECs) and pulmonary artery smooth muscle cells (PASMCs), leading to pulmonary vascular remodeling in pulmonary hypertension (PH). One possible mechanism is that circRNAs can regulate the function of PAECs and PASMCs by acting as miRNA sponge. However, other potential mechanisms of action of circRNAs are still being actively explored in PH. This paper presents a systematic review of the biogenesis, biological characterization, relevant underlying functions, and future perspectives for studies of circRNAs in the pathogenesis of PH.

Evaluating the Effect of Circ-Sirt1 on the Expression of SIRT1 and Its Role in Pathology of Pulmonary Hypertension

Pulmonary arterial hypertension (PAH) is a disease that plagues a major portion of the world's population, and there is currently no effective cure for this ailment. The proliferation and migration of pulmonary artery smooth muscle cells (PASMC) are known to be the pathological basis of pulmonary vascular remodeling in pulmonary hypertension. Studies in the past have shown involvement of CircRNA in the pathology of pulmonary as well as cardiovascular diseases. However, there are very few studies that have analyzed the relationship between CircRNA and PAH. The aim of this study was to explore this relationship by using rat PAH model. A hypoxic, PAH rat model was constructed for this study and the subsequently produced hypoxia-induced rat PASMC cells were utilized to demonstrate the reduction in expression of circular RNA of Silent information regulator factor 2-related enzyme 1 (circ-Sirt1) and SIRT1 mRNA in response to hypoxia, through cell function tests, cell rescue tests, and physical tests. We found that the expression of circ-Sirt1 and SIRT1 decreased in the PAH rat model induced by hypoxia. It was also revealed that the overexpression of circ-SIRT1 increased SIRT1 levels, but inhibited the expression of transforming growth factor (TGF)-β1, Smad3, and Smad7, and weakened PASMC cell vitality, proliferation, and migration ability. The findings of the present study indicate that circ-Sirt1 regulates the expression of SIRT1 mRNA and inhibits TGF-β1/Smad3/Smad7 mediated proliferation and migration of PASMC. This provides a new insight into the molecular mechanism of pulmonary artery vascular remodeling in PAH and may aid in the development of novel therapeutic options for management of PAH.

ARL14 as a Prognostic Biomarker in Non-Small Cell Lung Cancer

Purpose

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related deaths worldwide. The mechanisms underlying NSCLC initiation and progression require further investigation. The purpose of this study was to investigate the role of ADP ribosylation factor-like GTPase 14 (ARL14) related to the progression of NSCLC.

Patients and Methods

We analyzed the correlation between clinical characteristics and ARL14 expression using data from The Cancer Genome Atlas (TCGA). Kaplan–Meier analysis was conducted to evaluate the prognostic value of ARL14 in NSCLC. Functions of ARL14 were identified by enrichment analysis. The relationship between ARL14 expression and immune cell infiltration was also studied. Furthermore, ARL14 expression was examined using immunohistochemistry, and its clinical significance was analyzed in 120 patients with NSCLC.

Results

Our study revealed that the expression level of ARL14 in patients with NSCLC was higher than that in normal tissues. Using TCGA data, higher ARL14 expression in lung adenocarcinoma was associated with residual tumor (P = 0.017), while it was associated with age (P = 0.003) and N stage (P = 0.009) in lung squamous cell carcinoma. Similar results were obtained from 120 patients with NSCLC. High ARL14 expression was associated with poor overall survival and progression-free survival in NSCLC. Multivariate analysis revealed that ARL14 was an independent risk factor for patients with NSCLC. Functional enrichment analysis indicated that ARL14 was related to the occurrence and development of tumors.

Conclusion

Increased ARL14 expression was considerably correlated with poor survival in NSCLC, and it might be a promising prognostic biomarker for NSCLC.

Non-Coding RNA Networks in Pulmonary Hypertension

Non-coding RNAs (ncRNAs) are involved in various cellular processes. There are several ncRNA classes, including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs). The detailed roles of these molecules in pulmonary hypertension (PH) remain unclear. We systematically collected and reviewed reports describing the functions of ncRNAs (miRNAs, lncRNAs, and circRNAs) in PH through database retrieval and manual literature reading. The characteristics of identified articles, especially the experimental methods, were carefully reviewed. Furthermore, regulatory networks were constructed using ncRNAs and their interacting RNAs or genes. These data were extracted from studies on pulmonary arterial smooth muscle cells, pulmonary artery endothelial cells, and pulmonary artery fibroblasts. We included 14 lncRNAs, 1 circRNA, 74 miRNAs, and 110 mRNAs in the constructed networks. Using these networks, herein, we describe the current knowledge on the role of ncRNAs in PH. Moreover, these networks actively provide an improved understanding of the roles of ncRNAs in PH. The results of this study are crucial for the clinical application of ncRNAs.

Implication of proliferation gene biomarkers in pulmonary hypertension

Objective/Background

Proliferation is a widely recognized trigger for pulmonary hypertension (PH), a life-threatening, progressive disorder of pulmonary blood vessels. This study was aimed to identify some proliferation associated genes/targets for better comprehension of PH pathogenesis.

Methods

Human pulmonary arterial smooth muscle cells (hPASMCs) were cultured in the presence or absence of human recombinant platelet derived growth factor (rhPDGF)-BB. Cells were collected for metabolomics or transcriptomics study. Gene profiling of lungs of PH rats after hypoxia exposure or of PH patients were retrieved from GEO database.

Results

90 metabolites (VIP score >1, fold change >2 or <0.5 and p < .05) and 2701 unique metabolism associated genes (MAGs) were identified in rhPDGF-BB treated hPASMCs compared to control cells. In addition, 1151 differentially expressed genes (313 upregulated and 838 downregulated) were identified in rhPDGF-BB treated hPASMCs compared to control cells (fold change >2 or <0.5 and p < .05). 152 differentially expressed MAGs were then determined, out of which 9 hub genes (IL6, CXCL8, CCL2, CXCR4, CCND1, PLAUR, PLAU, HBEGF and F3) were defined as core proliferation associated hub genes in protein proten interaction analysis. In addition, the hub gene-based LASSO model can predict the occurrence of PH (AUC = 0.88). The expression of CXCR4, as one of the hub genes, was positively correlated to immune cell infiltrates.

Conclusion

Our findings revealed some key proliferation associated genes in PH, which provide the crucial information concerning complex metabolic reprogramming and inflammatory modulation in response to proliferation signals and might offer therapeutic gains for PH.

circ‑Grm1 promotes pulmonary artery smooth muscle cell proliferation and migration via suppression of GRM1 expression by FUS

Pulmonary arterial hypertension is a progressive and fatal disease. Recent studies suggest that circular RNA (circRNAs/circs) can regulate various biological processes, including cell proliferation. Therefore, it is possible that circRNA may have important roles in pulmonary artery smooth muscle cell proliferation in hypoxic pulmonary hypertension (HPH). The aim of the present study was to determine the role and mechanism of circRNA‑glutamate metabotropic receptor 1 (circ‑Grm1; mmu_circ_0001907) in pulmonary artery smooth muscle cell (PASMC) proliferation and migration in HPH. High‑throughput transcriptome sequencing was used to screen circRNAs and targeted genes involved in HPH. Cell Counting Kit‑8 (CCK‑8), 5‑ethynyl‑2‑deoxyuridine and wound healing assays were employed to assess cell viability and migration. Reverse transcription‑quantitative PCR and western blotting were used to detect target gene expression in different groups. Bioinformatical approaches were used to predict the interaction probabilities of circ‑Grm1 and Grm1 with FUS RNA binding protein (FUS). The interactions of circ‑Grm1, Grm1 and FUS were evaluated using RNA silencing and RNA immunoprecipitation assays. The results demonstrated that circ‑Grm1 was upregulated in hypoxic PASMCs. Further experiments revealed that the knockdown of circ‑Grm1 could suppress the proliferation and migration of hypoxic PASMCs. Transcriptome sequencing revealed that Grm1 could be the target gene of circ‑Grm1. It was found that circ‑Grm1 could competitively bind to FUS and consequently downregulate Grm1. Moreover, Grm1 could inhibit the function of circ‑Grm1 by promoting the proliferative and migratory abilities of hypoxic PASMCs. The results also demonstrated that circ‑Grm1 influenced the biological functions of PASMCs via the Rap1/ERK pathway by regulating Grm1. Overall, the current results suggested that circ‑Grm1 was associated with HPH and promoted the proliferation and migration of PASMCs via suppression of Grm1 expression through FUS.

Effect of Methylation Status of lncRNA-MALAT1 and MicroRNA-146a on Pulmonary Function and Expression Level of COX2 in Patients With Chronic Obstructive Pulmonary Disease

This study aimed to investigate the role of methylation of MALAT1 and miR-146a in the pathogenesis of chronic obstructive pulmonary disease (COPD). COPD patients were grouped according to their methylation status of MALAT1 and miR-146a promoters, and we found that forced vital capacity, volume that has been exhaled at the end of the first second of forced expiration, and diffusion capacity for carbon monoxide were the highest in the MALAT1 HYPO + miR-146a HYPER group and lowest in the MALAT1 HYPER + miR-146a HYPO group, and COPD patients with hypermethylated MALAT1 showed lower expression of MALAT1 than that in the COPD patients with hypomethylated MALAT1. Meanwhile, miR-146a was the most significantly upregulated in the MALAT1 HYPER + miR-146a HYPO group and the most significantly downregulated in the MALAT1 HYPO + miR-146a HYPER group. Both prostaglandin E₁ and cyclooxygenase 2 (COX2) expression were the highest in the MALAT1 HYPO + miR-146a HYPER group and the lowest in the MALAT1 HYPER + miR-146a HYPO group. In conclusion, our results established a MALAT1/miR-146a/COX2 signaling axis. The overexpression of MALAT1 could increase the expression of COX2 by inhibiting the expression of miR-146a, thus affecting the pulmonary function of COPD patients.

Research progress on biomarkers of pulmonary embolism

OBJECTIVES

To present a review on the traditional and new biomarkers of pulmonary embolism (PE).

DATA SOURCE

A systematic search has been carried out using keywords as PE, biomarker, diagnosis and risk stratification.

RESULTS

The results of this work have been structured into three parts: first, conventional biomarkers for vascular, cardiac and inflammation, including static markers and dynamic markers for measuring the time course; next, a review of new biomarkers in recent years, such as RNAs and markers obtained through proteomics and mass spectrometry; finally, use of new detection methods to directly detect the activity of existing markers, such as the determination of coagulation factor II and plasmin activities based on the proteolytic activation of an engineered zymogen.

CONCLUSIONS

This work summarized the characteristics of current traditional biomarkers for clinical diagnosis and risk stratification of PE, as well as a series of newly discovered biomarkers obtained through various clinical experimental methods.

circ_0038467 promotes PM2.5-induced bronchial epithelial cell dysfunction

Purpose

This study was to explore the toxicological mechanisms by which PM2.5 causes lung dysfunction.

Methods

The expression of circ_0038467 and miR-138-1-3p in PM2.5-induced human bronchial epithelial cell line BEAS-2B was detected by RT-qPCR. The effects of circ_0038467 and miR-138-1-3p on proliferation, apoptosis, and inflammatory cytokines (IL-6 and IL-8) in PM2.5-induced BEAS-2B were determined using cell counting kit-8, flow cytometry, western blot, and enzyme-linked immunosorbent assay, respectively. The levels of nuclear factor kappa B (NF-κB) pathway-related protein were also analyzed by western blot. The binding interaction between circ_0038467 and miR-138-1-3p was confirmed by dual-luciferase reporter assay and RNA immunoprecipitation assay and pull-down assay.

Results

circ_0038467 expression was increased by PM2.5 treatment in BEAS-2B cells in time- and dose-dependent methods, and knockdown of circ_0038467 reversed PM2.5-triggered BEAS-2B cell death and inflammatory response. miR-138-1-3p was decreased by PM2.5 treatment, and restoration of miR-138-1-3p attenuated PM2.5-induced BEAS-2B cell injury. In a mechanical study, we found circ_0038467 directly bound to miR-138-1-3p, and further rescue experiments exhibited miR-138-1-3p inhibition partially overturned the regulatory functions of circ_0038467 knockdown in PM2.5-induced BEAS-2B cells.

Conclusion

circ_0038467 provided a potential therapeutic strategy for future clinic intervention in air pollution-triggered lung dysfunction.

Bioinformatic analysis and validation of microRNA-508-3p as a protective predictor by targeting NR4A3/MEK axis in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) featured a debilitating progressive disorder. Here, we intend to determine diagnosis‐valuable biomarkers for PAH and decode the fundamental mechanisms of the biological function of these markers. Two mRNA microarray profiles (GSE70456 and GSE117261) and two microRNA microarray profiles (GSE55427 and GSE67597) were mined from the Gene Expression Omnibus platform. Then, we identified the differentially expressed genes (DEGs) and differentially expressed miRNAs (DEMs), respectively. Besides, we investigated online miRNA prediction tools to screen the target gene of DEMs. In this study, 185 DEGs and three common DEMs were screened as well as 1266 target genes of the three DEMs were identified. Next, 16 overlapping dysregulated genes from 185 DEGs and 1266 target gene were obtained. Meanwhile, we constructed the miRNA gene regulatory network and determined miRNA‐508‐3p‐NR4A3 pair for deeper exploring. Experiment methods verified the functional expression of miR‐508‐3p in PAH and its signalling cascade. We observed that ectopic miR‐508‐3p expression promotes proliferation and migration of pulmonary artery smooth muscle cell (PASMC). Bioinformatic, dual‐luciferase assay showed NR4A3 represents directly targeted gene of miR‐508‐3p. Mechanistically, we demonstrated that down‐regulation of miR‐508‐3p advances PASMC proliferation and migration via inducing NR4A3 to activate MAPK/ERK kinase signalling pathway. Altogether, our research provides a promising diagnosis of predictor and therapeutic avenues for patients in PAH.

Silencing circPVT1 enhances radiosensitivity in non-small cell lung cancer by sponging microRNA-1208

BACKGROUND

Radiotherapy is one of main useful therapies in non-small cell lung cancer (NSCLC). Nevertheless, the underlying mechanism between NSCLC cell radiosensitivity and effective treatment remains unclear.

OBJECTIVE

The aim is to explore the relationship between circular (circ) RNA and NSCLC cell radiosensitivity.

METHODS

CircRNA plasmacytoma variant translocation 1 (PVT1) and microRNA (miR)-1208 expression in NSCLC cells were assessed using quantitative reverse transcriptase PCR (qRT-PCR). NSCLC cells were transfected with si-PVT1 or miR-1208 inhibitor and then exposed to irradiation. Cellular biology behaviors were detected using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), Terminal deoxynucleotidyl transferase dUTP Nick-End Labeling (TUNEL), colony formation, invasion and western blot. Additionally, binding between circPVT1 and miR-1208 was testified by dual-luciferase reporter and RIP assay.

RESULTS

CircPVT1 was upregulated in NSCLC cells after irradiation treatment. Silencing circPVT1 induced inhibition of NSCLC cell growth and invasion, accompanied by cell apoptosis and γ-H2AX expression. Moreover, NSCLC cell proliferation and invasion was further inhibited by irradiation treatment in circPVT1-silenced cells, indicating a strong radiosensitivity of NSCLC cells. CircPVT1 functions as a competing endogenous RNA of miR-1208. Silencing miR-1208 reversed NSCLC cell sensitivity response to irradiation and activated PI3K/AKT/mTOR pathway in circPVT1-silenced cells.

CONCLUSIONS

Silencing circPVT1 enhanced radiosensitivity of NSCLC cells by sponging miR-1208.

CircANKRD11 Knockdown Protects HPMECs from Cigarette Smoke Extract-Induced Injury by Regulating miR-145-5p/BRD4 Axis

Background

Chronic obstructive pulmonary disease (COPD) is a major cause of death because of its high incidence and mortality, which is chiefly resulted from cigarette smoke exposure. A large number of studies show that circular RNA (circRNA) participates in regulating COPD process. This study aims to reveal the role of circRNA ankyrin repeat domain 11 (circANKRD11) in cigarette smoke extract (CSE)-induced cell apoptosis, inflammation, and oxidative stress.

Methods

The expression of circANKRD11, microRNA-145-5p (miR-145-5p) and bromodomain-containing 4 (BRD4) mRNA was detected by quantitative real-time polymerase chain reaction. The expression of apoptosis-related proteins and BRD4 protein was determined by Western blot. Cell apoptosis was detected by flow cytometry and Western blot. Cell inflammation was demonstrated by determining the levels of interleukin-1β (IL-1β), IL-6 and tumor necrosis factor-α (TNF-α) through enzyme-linked immunosorbent assay. Oxidative stress was investigated by the reactive oxygen species (ROS) and malondialdehyde (MDA) determination assays as well as superoxide dismutase (SOD) activity assay. The binding relationship between miR-145-5p and circANKRD11 or BRD4 was predicted by circinteractome or MicroT_CDS online database, and identified by dual-luciferase reporter, RNA immunoprecipitation or RNA pull-down assay.

Results

CircANKRD11 and BRD4 expression were increased, whereas miR-145-5p expression was decreased in the lung tissues of smokers with or without COPD and CSE-induced HPMECs compared with the lung tissues of non-smokers as well as untreated HPMECs, respectively. CircANKRD11 silencing ameliorated CSE-induced cell apoptosis, inflammation, and oxidative stress. CircANKRD11 acted as a sponge of miR-145-5p, and regulated CSE-induced cell injury via sponging miR-145-5p. Additionally, miR-145-5p mimics protected against CSE-induced cell injury through targeting BRD4.

Conclusion

CircANKRD11 absence protected HPMECs from CSE-induced injury by regulating BRD4 through associating with miR-145-5p, which demonstrated that circANKRD11 had the potential to act as a diagnosis biomarker for smoker-caused COPD.

Circular RNA-HIPK3 regulates human pulmonary artery endothelial cells function and vessel growth by regulating microRNA-328-3p/STAT3 axis

The proliferation and migration of pulmonary artery endothelial cells are the pathological basis of pulmonary vascular remodeling with pulmonary hypertension. Recent studies have shown that circular RNA (circRNA) regulates biological processes in various vascular diseases, including pulmonary arterial hypertension. It has been reported that circRNA regulates the vascular endothelial cells’ function. Therefore, circRNA may have crucial roles in human pulmonary artery endothelial cells (hPAECs) proliferation, migration, and tube formation in pulmonary arterial hypertension. In this study, we aimed to discover the role and mechanism of circular RNA HIPK3 (circHIPK3) in the proliferation and migration of pulmonary hypertension hPAECs. First, we used platelet-derived growth factor—stimulated hPAECs as a cellular model of pulmonary arterial hypertension. The results showed that platelet-derived growth factor promoted hPAECs proliferation, migration, and tube formation. Notably, platelet-derived growth factor upregulated the expression of circHIPK3 in hPAECs and regulated their proliferation, migration, and angiogenesis. Mechanistically, we confirmed miR-328-3p was copiously pulled down by circHIPK3 in hPAECs. Luciferase reporter and RNA immunoprecipitation assays further indicated the cytoplasmic interactions between circHIPK3 and miR-328-3p. Subsequently, we found that circHIPK3 might increase the expression of STAT3 by sponging miR-328-3p. Collectively, our results demonstrated that the circHIPK3-miR-328-3p-STAT3 axis contributed to the pathogenesis of pulmonary arterial hypertension by stimulating hPAECs proliferation, migration, and angiogenesis. The circHIPK3 has an accelerated role in pulmonary arterial hypertension development, implicating the potential values of circHIPK3 in pulmonary arterial hypertension therapy.

Circular RNAs: new biomarkers of chemoresistance in cancer

Chemotherapeutics are validated conventional treatments for patients with advanced cancer. However, with continual application of chemotherapeutics, chemoresistance, which is often predictive of poor prognosis, has gradually become a concern in recent years. Circular RNAs (circRNAs), a class of endogenous noncoding RNAs (ncRNAs) with a closed-loop structure, have been reported to be notable targets and markers for the prognosis, diagnosis, and treatment of many diseases, particularly cancer. Although dozens of studies have shown that circRNAs play major roles in drug-resistance activity in tumors, the mechanisms by which circRNAs affect chemoresistance have yet to be explored. In this review, we describe the detailed mechanisms of circRNAs and chemotherapeutics in various cancers and summarize potential therapeutic targets for drug-resistant tumors.

Pseudogenes in Cardiovascular Disease

Cardiovascular disease is the main disease that affects human life span. In recent years, the disease has been increasingly addressed at the molecular levels, for example, pseudogenes are now known to be involved in the pathogenesis and development of cardiovascular diseases. Pseudogenes are non-coding homologs of protein-coding genes and were once called “junk gene.” Since they are highly homologous to their functional parental genes, it is somewhat difficult to distinguish them. With the development of sequencing technology and bioinformatics, pseudogenes have become readily identifiable. Recent studies indicate that pseudogenes are closely related to cardiovascular diseases. This review provides an overview of pseudogenes and their roles in the pathogenesis of cardiovascular diseases. This new knowledge adds to our understanding of cardiovascular disease at the molecular level and will help develop new biomarkers and therapeutic approaches designed to prevent and treat the disease.

Hsa_circ_0006872 promotes cigarette smoke-induced apoptosis, inflammation and oxidative stress in HPMECs and BEAS-2B cells through the miR-145-5p/NF-κB axis

Cigarette smoke is a major cause of chronic obstructive pulmonary disease (COPD). Circular RNAs (circRNAs) are involved in regulating various biological processes. This study aimed to explore the role and molecular basis of hsa_circ_0006872 in cigarette smoke extract (CSE)-induced cell injury. HPMECs and BEAS-2B cells were treated with CSE to mimic COPD in vitro. The levels of hsa_circ_0006872 and miR-145-5p were measured by quantitative real-time polymerase chain reaction. Cell proliferation was assessed via Cell Counting Kit-8 (CCK-8) and colony formation assays. Flow cytometry was used to evaluate apoptosis and cell cycle. The levels of inflammatory factors were assayed via enzyme-linked immunosorbent assay (ELISA). The levels of oxidative stress markers were determined via commercial kits. The interaction between hsa_circ_0006872 and miR-145-5p was confirmed by dual-luciferase reporter assay and RNA immunoprecipitation assay. Protein expression was measured using Western blot assay. Hsa_circ_0006872 level was elevated in COPD patients and was negatively correlated with miR-145-5p level. CSE exposure promoted apoptosis, inflammation and oxidative stress of HPMECs and BEAS-2B cells, while hsa_circ_0006872 down-regulation undermined the effects. In addition, hsa_circ_0006872 silencing inhibited CSE-induced cell injury via regulating miR-145-5p. Moreover, CSE contributed to the activation of NF-κB pathway through hsa_circ_0006872/miR-145-5p axis. Hsa_circ_0006872 facilitated CSE-triggered apoptosis, inflammation and oxidative stress in HPMECs and BEAS-2B cells by regulating miR-145-5p/NF-κB pathway.

Regulation of circular RNAs act as ceRNA in a hypoxic pulmonary hypertension rat model

To explore potential critical genes and identify circular RNAs (circRNAs) that act as the competitive endogenous RNA (ceRNA) in a hypoxic pulmonary hypertension (HPH) rat model. Constructed rat model, and a bioinformatics method was used to analyse differentially expressed (DE) genes and construct a circRNA-miRNA-mRNA ceRNA regulatory network. Then, qRT-PCR was used to verify. The significant DEcircRNAs/DEmiRNAs/DEmRNAs was showed, and a ceRNA network with 8 DEcircRNAs, 9 DEmiRNAs and 46 DEmRNAs were constructed. The functional enrichment suggested the inflammatory response, NF-κB signalling, MAPK cascade and Toll-like receptor were associated with HPH. Further assessment confirmed that circ_002723, circ_008021, circ_016925 and circ_020581 could have a potential ceRNA mechanism by sponging miR-23a or miR-21 to control downstream target gene and be involved in the pathophysiology of HPH. The qRT-PCR validation results were consistent with the RNA-Seq results. This study revealed potentially important genes, pathways and ceRNA regulatory networks in HPH.

The ER Stress/UPR Axis in Chronic Obstructive Pulmonary Disease and Idiopathic Pulmonary Fibrosis

Cellular protein homeostasis in the lungs is constantly disrupted by recurrent exposure to various external and internal stressors, which may cause considerable protein secretion pressure on the endoplasmic reticulum (ER), resulting in the survival and differentiation of these cell types to meet the increased functional demands. Cells are able to induce a highly conserved adaptive mechanism, known as the unfolded protein response (UPR), to manage such stresses. UPR dysregulation and ER stress are involved in numerous human illnesses, such as metabolic syndrome, fibrotic diseases, and neurodegeneration, and cancer. Therefore, effective and specific compounds targeting the UPR pathway are being considered as potential therapies. This review focuses on the impact of both external and internal stressors on the ER in idiopathic pulmonary fibrosis (IPF) and chronic obstructive pulmonary disease (COPD) and discusses the role of the UPR signaling pathway activation in the control of cellular damage and specifically highlights the potential involvement of non-coding RNAs in COPD. Summaries of pathogenic mechanisms associated with the ER stress/UPR axis contributing to IPF and COPD, and promising pharmacological intervention strategies, are also presented.