Expression Profile Of Exosomal LncRNA In Plasma Of Pancreatic Ductal Adenocarcinoma

ObjectivePancreatic cancer(PC)is insidious in origin,aggressive,fast progressing,late detection,lack of effective treatment,and a 5-year survival rate of less than 10%.Early detection and improved survival are urgent problems for PC research.It has been found that long non-coding RNA(lncRNA)in exosomes is involved in the regulation of cancer cell growth and migration.Pancreatic ductal adenocarcinoma(PDAC)is the most common type of PC pathology,accounting for 80%-90% of cases.This study aims to analyze the expression of exosomal lncRNAs in PDAC,explore their potential functions and possible regulatory pathways,and provide guidance for finding sensitive biomarkers and effective targets for PDAC.Methods(1)Collected plasma from 5 PDAC patients and healthy individuals each,applied isolation reagents to extract exosomes,and identified exosomes by electron microscopy and Nanoparticle tracking analyzer(NTA);(2)Applied high-throughput sequencing to identify the expression of exosomal lncRNAs and m RNAs in plasma of PDAC patients and healthy individuals;(3)Validated the expression of 8 target lncRNAs in PDAC plasma by Cancer Genome Atlas(TCGA)/Genotype-Tissue Expression(GTEx)database,quantitative real-time fluorescence polymerase chain reaction(RT-qPCR)technology to verify the expression of eight target lncRNAs in PDAC plasma and evaluate whether the results are consistent with the expression profiles;(4)Functional analysis of differential lncRNAs by Gene Ontology(GO)with Kyoto Gene and Genome(KEGG)and survival prediction by TCGA database;(5)Prediction of potential functions of lncRNAs using lncRNA-m RNA co-expression gene regulatory network.Results(1)Electron microscopy showed that the isolated exosomes were membranous vesicles with a diameter of about 100 nm.NTA results showed that the concentration of nanoparticles was 1.27E+11 per nm and the particle size range was 30-150 nm;(2)A total of 18540 exosomal lncRNAs were expressed in the plasma of PDAC and healthy individuals,of which 5851 were expressed in the plasma of PDAC patients,respectively up-regulated expression and 1055 down-regulated expression in the plasma of PDAC patients,respectively(≤2.0fold change,P﹤0.05);(3)The expression of eight genes,ABCD4,RP11-77P6.2,FLVCR1-AS1,HMBOX1,TUBA1 C,RP11-115C21.2,PRKG1-AS1,and MTATP6P1,was verified by database and RT-qPCR in five PDAC patients,showing general agreement with the sequencing assay results;(4)analysis of neighboring coding genes showed that the main functions of most genes were to regulate cell metabolism,apoptosis,protein binding and receptor binding,and the main regulatory pathways included the Erb B signaling pathway and tumor pathway that regulate cell proliferation and differentiation;(5)analysis of the regulatory network of co-expressed genes by key lncRNA-m RNA pairs that may play an important role in the pathogenesis of PDAC were identified.ConclusionOur study identified differences in the expression of exosomal lncRNAs in the plasma of PDAC patients and healthy individuals,and initially explored the expression profile of exosomal lncRNAs.In this study,we screened target lncRNA ABCD4,lncRNA FLVCR1-AS1,and lncRNA HMBOX1.These target exosomal lncRNAs may help to study the mechanisms related to the pathogenesis and progression of PDAC,and open up new directions for the diagnosis and treatment of PDAC.