Multifaceted roles of extracellular RNAs in different diseases

Extracellular RNAs(exRNAs) are novel circulating factors that can be used as biomarkers in various diseases. Their unique and diverse kinds, as well as their role as biomarkers, make them significant biomarkers. There has been immense work carried out since the discovery of exRNAs in circulation and other biological fluids to catalog and determine whether exRNAs may be utilized as indicators for health and illness. In this review, we aim to understand the current state of exRNAs in relation to various diseases and their potential as biomarkers. We will also review current issues and challenges faced in using exRNAs, with clinical and lab trials, that can be used as viable markers for different diseases.

Extracellular RNAs as potential biomarkers for cancer

The discovery that all cells secrete extracellular vesicles(EVs)to shuttle proteins and nucleic acids to recipient cells suggested they play an important role in intercellular communication.EVs are widely distributed in many body fluids,including blood,cerebrospinal fluid,urine and saliva.Exosomes are nano-sized EVs of endosomal origin that regulate many pathophysiological processes including immune responses,inflammation,tumour growth,and infection.Healthy individuals release exosomes with a cargo of different RNA,DNA,and protein contents into the circulation,which can be measured non-invasively as biomarkers of healthy and diseased states.Cancer-derived exosomes carry a unique set of DNA,RNA,protein and lipid reflecting the stage of tumour progression,and may serve as diagnostic and prognostic biomarkers for various cancers.However,many gaps in knowledge and technical challenges in EVs and extracellular RNA(exRNA)biology,such as mechanisms of EV biogenesis and uptake,exRNA cargo selection,and exRNA detection remain.The NIH Common Fund-supported exRNA Communication Consortium was launched in 2013 to address major scientific challenges in this field.This review focuses on scientific highlights in biomarker discovery of exosome-based exRNA in cancer and its possible clinical application as cancer biomarkers.

Inflammatory/immune-suppressive microenvironment characteristics of pancreatic cancer patients with Shi-Re syndrome identified by extracellular vesicle long RNA profiling

Background:Numerous long RNAs were detected in extracellular vesicles(EVs),some of which were related with the tissue origins and immune cell types.This study examined the molecular basis of different traditional Chinese medicine syndrome diagnoses(also called syndrome differentiation)in pancreatic ductal adenocarcinoma.Methods:128 pancreatic ductal adenocarcinoma patients with different syndrome diagnoses were retrospectively reviewed in this study.Long RNA sequencing was conducted to analyze the EV long RNA profile of plasma samples.Differentially regulated EV long RNAs were annotated and assessed for Gene Ontology pathway enrichment using DAVID.The online program xCell were used to perform the cell-type enrichment analysis.Results:An average of 15,000 annotated genes,mainly including messenger RNAs,were stably detected per sample.Different syndrome diagnoses exhibited unique EV mRNA expression profiles and therefore different enriched pathways.Gene Set Enrichment Analysis discovered transforming growth factor-βand kirsten rat sarcoma viral oncogene homolog signaling activation as the hallmarks of cancer with Shi-Re syndrome.Cell-type enrichment analysis also revealed a varied inflammation/immune cell type distribution among patients with or without Shi-Re diagnosis.Mast cells,platelets and Tregs were significantly enriched but basophils,common lymphoid progenitors,dendritic cells,and conventional dendritic cells were decreased in patients with Shi-Re diagnosis compared with patients without Shi-Re diagnosis.Conclusion:We identified the hallmarks of cancer with different syndrome diagnoses based on plasma EV long RNA sequencing.In particular,transforming growth factor-βand kirsten rat sarcoma viral oncogene homolog signaling activation were the hallmarks of Shi-Re syndrome,which contribute to shape an inflammatory/immune-suppressive tumor microenvironment in pancreatic ductal adenocarcinoma.

ExRNA Sequencing Results of Different Volumes of Serum

Circulating extracellular RNAs (exRNAs) are very important potential biomarkers of disease. But few have been reported the extracellular RNA profiles in serum. In this study, we tried to use RNA-seq technology to analyze the extracellular RNA by using low volume peripheral blood serum and compared the sequencing results between different volumes of serum (500 μl, 1.5 ml, 2.5 ml, 3.5 ml). According to the results, we found that most of the exRNA in the serum is lncRNA, protein_coding and MT-rRNA. And when the volume of serum is between 0.5 - 3.5 ml, the numbers and reads of exRNA, including the reads of circRNA, have not changed significantly. It indicates that the sequencing result of exRNA in serum has no significance with the initial serum volume.

Exosome and Exosomal MicroRNA: Trafficking, Sorting, and Function

Exosomes are 40–100 nm nano-sized vesicles that are released from many cell types into the extracellular space. Such vesicles are widely distributed in various body fluids. Recently,m RNAs and micro RNAs（mi RNAs） have been identified in exosomes, which can be taken up by neighboring or distant cells and subsequently modulate recipient cells. This suggests an active sorting mechanism of exosomal mi RNAs, since the mi RNA profiles of exosomes may differ from those of the parent cells. Exosomal mi RNAs play an important role in disease progression, and can stimulate angiogenesis and facilitate metastasis in cancers. In this review, we will introduce the origin and the trafficking of exosomes between cells, display current research on the sorting mechanism of exosomal mi RNAs, and briefly describe how exosomes and their mi RNAs function in recipient cells.Finally, we will discuss the potential applications of these mi RNA-containing vesicles in clinical settings.