Extracellular vesicle long RNA markers of early-stage lung adenocarcinoma.

Lung cancer screening by low-dose computed tomography (LDCT) can improve mortality rates among high-risk individuals, especially adenocarcinoma cases with characteristically poor prognosis, although high false-positive rates have limited its clinical application. The objective of our study was to identify biomarkers for early-stage lung adenocarcinoma (ie, tumor diameter <2 cm) through extracellular vesicle long RNA (evlRNA) sequencing. High throughput evlRNA sequencing and support vector machine (SVM) identification of candidate diagnostic marker transcripts were performed using serum samples obtained before lung surgery. A total of 145 upregulated and 363 downregulated differential genes (P value <.05, fold change >1.5) were identified between lung adenocarcinoma (LUAD) patients and benign controls. An SVM model based on a 23-gene signature could distinguish EV samples of LUAD patients from those of control subjects with 86.49% sensitivity, 95.00% specificity and 92.31% accuracy in the training set and 93.75% sensitivity, 85.71% specificity and 88.24% accuracy in the validation set. A 17-gene signature was then identified that could distinguish AIS patient samples from those of MIA/IAD patients with 93.33% sensitivity, 98.00% specificity, and 96.25% accuracy in the trainingset and 83.33% sensitivity, 96.55% specificity, and 94.29% accuracy in the validation set. EvlRNAs in serum show considerable diagnostic value for screening LUAD patients with tumor sizes <2 cm in conjunction with LDCT, potentially reducing false positive rates while improving mortality rates.

Copy Number Variations as Determinants of Colorectal Tumor Progression in Liquid Biopsies.

Over the years, increasing evidence has shown that copy number variations (CNVs) play an important role in the pathogenesis and prognosis of Colorectal Cancer (CRC). Colorectal adenomas are highly prevalent lesions, but only 5% of these adenomas ever progress to carcinoma. This review summarizes the different CNVs associated with adenoma-carcinoma CRC progression and with CRC staging. Characterization of CNVs in circulating free-RNA and in blood-derived exosomes augers well with the potential of using such assays for patient management and early detection of metastasis. To overcome the limitations related to tissue biopsies and tumor heterogeneity, using CNVs to characterize tumor-derived materials in biofluids provides less invasive sampling methods and a sample that collectively represents multiple tumor sites in heterogeneous samples. Liquid biopsies provide a source of circulating tumor DNA (ctDNA), circulating tumor cells (CTCs), tumor-derived exosomes (TDE), circulating free RNA, and non-coding RNA. This review provides an overview of the current diagnostic and predictive models from liquid biopsies.

Small and long RNA transcriptome of whole human cerebrospinal fluid and serum as compared to their extracellular vesicle fractions reveal profound differences in expression patterns and impacts on biological processes.

BACKGROUND: Next generation sequencing (NGS) of human specimen is expected to improve prognosis and diagnosis of human diseases, but its sensitivity urges for well-defined sampling and standardized protocols in order to avoid error-prone conclusions. METHODS: In this study, large volumes of pooled human cerebrospinal fluid (CSF) were used to prepare RNA from human CSF-derived extracellular vesicles (EV) and from whole CSF, as well as from whole human serum and serum-derived EV. In all four fractions small and long coding and non-coding RNA expression was analyzed with NGS and transcriptome analyses. RESULTS: We show, that the source of sampling has a large impact on the acquired NGS pattern, and differences between small RNA fractions are more distinct than differences between long RNA fractions. The highest percentual discrepancy between small RNA fractions and the second highest difference between long RNA fractions is seen in the comparison of CSF-derived EV and whole CSF. Differences between miR (microRNA) and mRNA fractions of EV and the respective whole body fluid have the potential to affect different cellular and biological processes. I.e. a comparison of miR in both CSF fractions reveals that miR from EV target four transcripts sets involved in neurobiological processes, whereas eight others, also involved in neurobiological processes are targeted by miR found in whole CSF only. Likewise, three mRNAs sets derived from CSF-derived EV are associated with neurobiological and six sets with mitochondrial metabolism, whereas no such mRNA transcript sets are found in the whole CSF fraction. We show that trace amounts of blood-derived contaminations of CSF can bias RNA-based CSF diagnostics. CONCLUSIONS: This study shows that the composition of small and long RNA differ significantly between whole body fluid and its respective EV fraction and thus can affect different cellular and molecular functions. Trace amounts of blood-derived contaminations of CSF can bias CSF analysis. This has to be considered for a meaningful RNA-based diagnostics. Our data imply a transport of EV from serum to CSF across the blood-brain barrier.

Plasma extracellular vesicle long RNA profiling identifies a diagnostic signature for the detection of pancreatic ductal adenocarcinoma.

OBJECTIVE: Pancreatic ductal adenocarcinoma (PDAC) is difficult to diagnose at resectable stage. Recent studies have suggested that extracellular vesicles (EVs) contain long RNAs. The aim of this study was to develop a diagnostic (d-)signature for the detection of PDAC based on EV long RNA (exLR) profiling. DESIGN: We conducted a case-control study with 501 participants, including 284 patients with PDAC, 100 patients with chronic pancreatitis (CP) and 117 healthy subjects. The exLR profile of plasma samples was analysed by exLR sequencing. The d-signature was identified using a support vector machine algorithm and a training cohort (n=188) and was validated using an internal validation cohort (n=135) and an external validation cohort (n=178). RESULTS: We developed a d-signature that comprised eight exLRs, including FGA, KRT19, HIST1H2BK, ITIH2, MARCH2, CLDN1, MAL2 and TIMP1, for PDAC detection. The d-signature showed high accuracy, with an area under the receiver operating characteristic curve (AUC) of 0.960, 0.950 and 0.936 in the training, internal validation and external validation cohort, respectively. The d-signature was able to identify resectable stage I/II cancer with an AUC of 0.949 in the combined three cohorts. In addition, the d-signature showed superior performance to carbohydrate antigen 19-9 in distinguishing PDAC from CP (AUC 0.931 vs 0.873, p=0.028). CONCLUSION: This study is the first to characterise the plasma exLR profile in PDAC and to report an exLR signature for the detection of pancreatic cancer. This signature may improve the prognosis of patients who would have otherwise missed the curative treatment window.

Clinical applications of extracellular vesicle long RNAs.

Extracellular vesicles (EVs), primarily exosomes and microvesicles, are critical intercellular mediators of communication. Over the past decade, improved knowledge and methodologies have enabled the detection and quantification of RNA species in EVs, despite their extremely low levels. Recently, EV-associated long RNAs (exLRs) have been drawing much attention. Delivered by EVs, they have higher stability, greater difference in temporal and spatial expression, and the capacity to remodel both proximal and distal recipient cells. These properties guarantee their roles as biomarkers, therapeutic targets, vaccines, and gene therapy agents in a wide range of human diseases. Despite the progress in this area of research, limitations in both knowledge and methodologies have hindered its further development. Herein, we comprehensively reviewed studies related to exLRs, including protein-coding messenger RNAs (mRNAs) and noncoding RNAs (long noncoding RNAs and circular RNAs) in EVs to indicate their value in the diagnosis and treatment of human diseases; we also present a series of yet unsettled issues in this novel area, hence providing insights for future studies.

Proximal disruptor aided ligation (ProDAL) of kilobase-long RNAs.

RNA with site-specific modification is a useful tool for RNA biology studies. However, generating kilobase (kb) -long RNA with internal modification at a site distant from RNA termini remains challenging. Here we report an enhanced splint ligation technique, proximal disruptor aided ligation (ProDAL), which allows adequate efficiency toward this purpose. The key to our approach is using multiple DNA oligonucleotides, 'proximal disruptors', to target the RNA substrate sequence next to the ligation site. The binding of disruptors helps to free the ligation site from intramolecular RNA basepairing, and consequently promotes more efficient formation of the pre-ligation complex and a higher overall ligation yield. We used naturally occurring 1.0 kb renilla and 1.9 kb firefly luciferase mRNA sequences to test the efficacy of our approach. ProDAL yielded 9-14% efficiency for the ligation between two RNA substrates, both of which were between 414 and 1313 nucleotides (nt) long. ProDAL also allowed similarly high efficiency for generating kb-long RNA with site-specific internal modification by a simple three-part ligation between two long RNA substrates and a modification-carrying RNA oligonucleotide. In comparison, classical splint ligation yielded a significantly lower efficiency of 0-2% in all cases. We expect that ProDAL will benefit studies involving kb-long RNAs, including translation, long non-coding RNAs, RNA splicing and modification, and large ribonucleoprotein complexes.

A review on recent advances in methods for site-directed spin labeling of long RNAs.

RNAs are important biomolecules that play essential roles in various cellular processes and are crucially linked with many human diseases. The key to elucidate the mechanisms underlying their biological functions and develop RNA-based therapeutics is to investigate RNA structure and dynamics and their connections to function in detail using a variety of approaches. Magnetic resonance techniques including paramagnetic nuclear magnetic resonance (NMR) and electron magnetic resonance (EPR) spectroscopies have proved to be powerful tools to gain insights into such properties. The prerequisites for paramagnetic NMR and EPR studies on RNAs are to achieve site-specific spin labeling of the intrinsically diamagnetic RNAs, which however is not trivial, especially for long ones. In this review, we present some covalent labeling strategies that allow site-specific introduction of electron spins to long RNAs. Generally, these strategies include assembly of long RNAs via enzymatic ligation of short oligonucleotides, co- and post-transcriptional site-specific labeling empowered with the unnatural base pair system, and direct enzymatic functionalization of natural RNAs. We introduce a few case studies to discuss the advantages and limitations of each strategy, and to provide a vision for the future development.

End-to-end RT-PCR of long RNA and highly structured RNA.

RNA molecules play important roles in numerous normal cellular processes and disease states, from protein coding to gene regulation. RT-PCR, applying the power of polymerase chain reaction (PCR) to RNA by coupling reverse transcription with PCR, is one of the most important techniques to characterize RNA transcripts and monitor gene expression. The ability to analyze full-length RNA transcripts and detect their expression is critical to decipher their biological functions. However, due to the low processivity of retroviral reverse transcriptases (RTs), we can only monitor a small fraction of long RNA transcripts, especially those containing stable secondary and tertiary structures. The full-length sequences can only be deduced by computational analysis, which is often misleading. Group II intron-encoded RTs are a new type of RT enzymes. They have evolved specialized structural elements that unwind template structures and maintain close contact with the RNA template. Therefore, group II intron-encoded RTs are more processive than the retroviral RTs. The discovery, optimization and deployment of processive group II intron RTs provide us the opportunity to analyze RNA transcripts with single molecule resolution. MarathonRT, the most processive group II intron RT, has been extensively optimized for processive reverse transcription. In this chapter, we use MarathonRT to deliver a general protocol for long amplicon generation by RT-PCR, and also provide guidance for troubleshooting and further optimization.

Plasma Extracellular Vesicle Long RNA in Diagnosis and Prediction in Small Cell Lung Cancer.

(1) Introduction: The aim of this study was to identify the plasma extracellular vesicle (EV)-specific transcriptional profile in small-cell lung cancer (SCLC) and to explore the application value of plasma EV long RNA (exLR) in SCLC treatment prediction and diagnosis. (2) Methods: Plasma samples were collected from 57 SCLC treatment-naive patients, 104 non-small-cell lung cancer (NSCLC) patients and 59 healthy participants. The SCLC patients were divided into chemo-sensitive and chemo-refractory groups based on the therapeutic effects. The exLR profiles of the plasma samples were analyzed by high-throughput sequencing. Bioinformatics approaches were used to investigate the differentially expressed exLRs and their biofunctions. Finally, a t-signature was constructed using logistic regression for SCLC treatment prediction and diagnosis. (3) Results: We obtained 220 plasma exLRs profiles in all the participants. Totals of 5787 and 1207 differentially expressed exLRs were identified between SCLC/healthy controls, between the chemo-sensitive/chemo-refractory groups, respectively. Furthermore, we constructed a t-signature that comprised ten exLRs, including EPCAM, CCNE2, CDC6, KRT8, LAMB1, CALB2, STMN1, UCHL1, HOXB7 and CDCA7, for SCLC treatment prediction and diagnosis. The exLR t-score effectively distinguished the chemo-sensitive from the chemo-refractory group (p = 9.268 × 10-9) with an area under the receiver operating characteristic curve (AUC) of 0.9091 (95% CI: 0.837 to 0.9811) and distinguished SCLC from healthy controls (AUC: 0.9643; 95% CI: 0.9256-1) and NSCLC (AUC: 0.721; 95% CI: 0.6384-0.8036). (4) Conclusions: This study firstly characterized the plasma exLR profiles of SCLC patients and verified the feasibility and value of identifying biomarkers based on exLR profiles in SCLC diagnosis and treatment prediction.

Current challenges and best practices for cell-free long RNA biomarker discovery.

The analysis of biomarkers in biological fluids, also known as liquid biopsies, is seen with great potential to diagnose complex diseases such as cancer with a high sensitivity and minimal invasiveness. Although it can target any biomolecule, most liquid biopsy studies have focused on circulating nucleic acids. Historically, studies have aimed at the detection of specific mutations on cell-free DNA (cfDNA), but recently, the study of cell-free RNA (cfRNA) has gained traction. Since 2020, a handful of cfDNA tests have been approved for therapy selection by the FDA, however, no cfRNA tests are approved to date. One of the main drawbacks in the field of RNA-based liquid biopsies is the low reproducibility of the results, often caused by technical and biological variability, a lack of standardized protocols and insufficient cohorts. In this review, we will identify the main challenges and biases introduced during the different stages of biomarker discovery in liquid biopsies with cfRNA and propose solutions to minimize them.

Dynamic changes of plasma extracellular vesicle long RNAs during perioperative period of colorectal cancer.

Extracellular vesicles (EVs) long RNAs (exLRs) have been shown to be indicators for the diagnosis and prognosis of colorectal cancer (CRC); however, the dynamic changes of exLRs during perioperative period and their cellular sources in CRC remains largely unknown. In this study, exLR sequencing (exLR-seq) was performed on plasma samples from three CRC patients at four time points (before surgery [T0], after extubation [T1], 1 day after surgery [T2], and 3 days after surgery [T3]). Bioinformatics approaches were used to investigate the profile and biofunctions of exLRs and their cellular sources. Greater than 12,000 mRNAs and 2,000 lncRNAs were reliably detected in each exLR-seq sample. Compared with T0, there were 110 differentially expressed genes (DEGs) in T1, 60 DEGs in T2, and 50 DEGs in T3. A total of 11 DEGs were found at all three time points and were related to membrane potential. In addition, compared to T0, 22 differentially expressed lncRNAs (DELRs) were found in T1, 19 DELRs in T2, and 38 DELRs in T3. Moreover, only three DELRs were detected at all three time points. Interestingly, EVs from CD8 + T cells, CD4+ memory T cells and NK cells decreased after surgery and the absolute quantity of EVs from immune cells were reduced as well. In summary, this study was the first to characterize the dynamic changes of exLRs during perioperative period and the cellular sources. These findings established the foundation for further studies involving the effects of these dynamically changed exLRs on CRC.

Circulating EVs long RNA-based subtyping and deconvolution enable prediction of immunogenic signatures and clinical outcome for PDAC.

Identification of clinically applicable molecular subtypes of pancreatic ductal adenocarcinoma (PDAC) is crucial to improving patient outcomes. However, the traditional tissue-dependent transcriptional subtyping strategies are invasive and not amenable to routine clinical evaluation. In this study, we developed a circulating extracellular vesicle (cEV) long RNA (exLR)-based PDAC subtyping method and provided exLR-derived signatures for predicting immunogenic features and clinical outcomes in PDAC. We enrolled 426 individuals, among which 227 PDACs served as an internal cohort, 118 PDACs from two other medical centers served as an independent validation cohort, and 81 healthy individuals served as the control. ExLR sequencing was performed on all plasma samples. We found that PDAC could be categorized into three subtypes based on plasma exLR profiles. Each subpopulation showed its own molecular features and was associated with patient clinical prognosis. The immunocyte-derived cEV fractions were altered among PDAC subtypes and interconnected with tumor-infiltrating lymphocytes in cancerous tissue. Additionally, we found a significant concordance of immunoregulators between tissue and blood EVs, and we harvested potential PDAC therapeutic targets. Most importantly, we constructed a nine exLR-derived, tissue-applicable signature for prognostic assessment of PDAC. The circulating exLR-based features may offer an attractive platform for personalized treatment and predicting patient outcomes in multiple types of cancer.

EV-origin: Enumerating the tissue-cellular origin of circulating extracellular vesicles using exLR profile.

Extracellular vesicles (EVs) are complex ecosystems that can be derived from all body cells and circulated in the body fluids. Characterizing the tissue-cellular source contributing to circulating EVs provides biological information about the cell or tissue of origin and their functional states. However, the relative proportion of tissue-cellular origin of circulating EVs in body fluid has not been thoroughly characterized. Here, we developed an approach for digital EVs quantification, called EV-origin, that enables enumerating of EVs tissue-cellular source contribution from plasma extracellular vesicles long RNA sequencing profiles. EV-origin was constructed by the input matrix of gene expression signatures and robust deconvolution algorithm, collectively used to separate the relative proportions of each tissue or cell type of interest. EV-origin respectively predicted the relative enrichment of seven types of hemopoietic cells and sixteen solid tissue subsets from exLR-seq profile. Using the EV-origin approach, we depicted an integrated landscape of the traceability system of plasma EVs for healthy individuals. We also compared the heterogenous tissue-cellular source components from plasma EVs samples with diverse disease status. Notably, the aberrant liver fraction could reflect the development and progression of hepatic disease. The liver fraction could also serve as a diagnostic indicator and effectively separate HCC patients from normal individuals. The EV-origin provides an approach to decipher the complex heterogeneity of tissue-cellular origin in circulating EVs. Our approach could inform the development of exLR-based applications for liquid biopsy.

O papel dos RNAs longos não codificantes na insuficiência cardíaca: uma revisão de literatura / The role of non-coding long RNAs in heart failure: a literature review / El papel de las RNAs largas no codificantes en la insuficiencia cardiaca: una revisión de la literatura

A Insuficiência Cardíaca (IC) é uma das principais causas de internação hospitalar no mundo e tem um elevado grau de morbidade e mortalidade, sendo um grave problema de saúde pública. Os lncRNAs (RNAs longo não codificantes), têm funções regulatórias transcricionais e/ou pós transcricionais bem complexas e que ainda não são totalmente claras, mas que podem exercer influência sobre as doenças cardiovasculares, dentre elas a IC. Assim o estudo teve como objetivo identificar na literatura o papel dos lncRNAs na patogênese da IC por meio de uma revisão integrativa com busca sistemática. Foram considerados elegíveis para leitura e composição do estudo 33 artigos e os principais papéis dos lncRNA na IC foram relatados como possíveis marcadores biológicos para diagnóstico e prognóstico da doença devido a sua expressividade na corrente sanguínea. Além disso, os lncRNAs podem estar relacionados à capacidade funcional uma vez que o aumento ou diminuição de sua expressão promove redução da apoptose de células endoteliais, melhora a disfunção cardíaca, distúrbios de contratilidade e dos canais de cálcio em pacientes com IC. Portanto, os lncRNAs parecem estar envolvidos na patogênese e/ou fisiopatologia da IC, podendo ser utilizados como biomarcadores genéticos com sensibilidade e especificidade semelhantes ou superiores aos empregados atualmente no diagnóstico e prognóstico da IC.

Heart Failure (HF) is one of the main causes of hospitalization worldwide and has a high degree of morbidity and mortality being considered a public health pro- blem. lncRNAs (non-coding long RNAs) have very complex transcriptional and/or post- transcriptional regulatory functions that are still not entirely clear but may influence car- diovascular diseases, including HF. Thus, the study aimed to identify in the literature the role of lncRNAs in the pathogenesis of HF through an integrative review with a systema- tic search. A total of 33 articles were considered eligible for reading and composition of the study. The roles of lncRNA in HF were reported as possible biological markers for the diagnosis and prognosis of the disease due to its expressiveness in the bloodstream. In addition, lncRNAs may be related to functional capacity since the increase or decrease in their expression promotes a reduction in endothelial cell apoptosis, and improves car- diac dysfunction, contractility, and calcium channel disorders in patients with HF. The- refore, lncRNAs seem to be involved in the pathogenesis and/or pathophysiology of HF and can be used as genetic biomarkers with sensitivity and specificity similar or superior to those currently employed in the diagnosis and prognosis of HF.

La Insuficiencia Cardiaca (IC) es una de las principales causas de hospita- lización en el mundo y tiene un alto grado de morbimortalidad considerándose un pro- blema de salud pública. Los lncRNAs (ARN largos no codificantes) tienen funciones re- guladoras transcripcionales y/o post-transcripcionales muy complejas que aún no están del todo claras pero que pueden influir en las enfermedades cardiovasculares, incluida la IC. Así pues, el estudio se propuso identificar en la literatura el papel de los lncRNAs en la patogénesis de la IC mediante una revisión integradora con una búsqueda sistemática. Un total de 33 artículos fueron considerados elegibles para su lectura y composición del estudio. Las funciones de los lncRNA en la IC se señalaron como posibles marcadores biológicos para el diagnóstico y pronóstico de la enfermedad debido a su expresividad en el torrente sanguíneo. Además, los lncRNAs pueden estar relacionados con la capacidad funcional, ya que el aumento o disminución de su expresión promueve una reducción de la apoptosis de las células endoteliales y mejora la disfunción cardiaca, la contractilidad y los trastornos de los canales de calcio en pacientes con IC. Por tanto, los lncRNAs parecen estar implicados en la patogénesis y/o fisiopatología de la IC y pueden ser utili- zados como biomarcadores genéticos con sensibilidad y spe-cificidad similares o superi- ores a los empleados actualmente en el diagnóstico y pronóstico de la IC.

Kinetic model of double-stranded RNA formation during long RNA replication by Qß replicase.

Qß replicase is an RNA-dependent RNA polymerase, which synthesizes the complementary RNA using a single-stranded RNA as a template. The formation of non-replicable double-stranded RNA (dsRNA) by hybridization between newly synthesized RNA and the template RNA hinders the broader application of Qß replicase. Here, we developed a kinetic model of Qß RNA replication consisting of two reaction pathways of dsRNA formation, which quantitatively explains the dynamics of dsRNA formation of three template RNAs. We also found that part of the Qß phage genomic RNA sequence including the central hairpin loop significantly decreases the rate of dsRNA formation.