| Objective: Lung cancer remains the leading cause of cancer-related mortality worldwide.Non-small cell lung cancer(NSCLC)is the most common type of lung cancer.In spite of current advances in chemotherapy and molecular targeting therapy for NSCLC,the overall 5-year survival rate remains 21%.Early diagnosis is an effective method to improve the prognosis of NSCLC patients.Currently,imageology is the predominant screening method used for detection of NSCLC,however,it may lead to overdiagnosis due to high false-positive rates.In addition,serum protein biomarkers currently used in clinical practice exhibited lower diagnostic sensitivity and specificity.Therefore,a novel biomarker for diagnosis of NSCLC is urgently needed.Exosomes,a kind of extracellular membranous vesicle with a diameter of approximately 40-100 nm,are present in various human body fluids,including peripheral blood.Long non-coding RNAs(lncRNAs)are broadly defined as a class of transcripts longer than 200 nucleotides with limited protein-coding capacity.It has been confirmed that lncRNAs play critical roles in the initiation and progression of NSCLC.Recently,a large amount of evidence has demonstrated that tumor-derived lncRNAs can be packaged into exosomes and transported in circulating blood,which makes exosomal lncRNAs as an ideal non invasive biomarker for cancer detection.However,little is known about the clinical utility of exosomal lncRNAs in NSCLC.In this study,we investigate the expression of serum exosomal lncRNAs in NSCLC patients and explore the diagnostic value of exosomal lncRNAs for NSCLC.Methods: Serum exosomes from NSCLC patients were isolated by a polymer precipitation kit and identified by TEM,NTA and western blot analysis.The lncRNAs that reported highly expressed in the NSCLC tissues were selected as candidates.Then,the levels of candidate lncRNAs were detected by qRT-PCR by training set and validation set.The correlations between the levels of exosomal lncRNAs and clinical characteristics were analyzed by Chi-square test and Fisher’s exact test.Additionally,the change of the expression of exosomal lncRNAs was measured after RNase treatment and room temperature incubation.The concentration of serum Cyfra21-1 was tested by the chemiluminescence method.Finally,the diagnostic efficiency of the exosomal lncRNAs and Cyfra21-1 was evaluated by ROC curve analysis.Results: Exosomes were isolated successfully from serum by commercial kit.The isolated exosomes had double-layer membrane structure.The size distribution of exosomes was approximately 100 nm in diameter.Moreover,western blot analysis demonstrated the presence of the specific exosome marker protein(CD9 and CD63)in the exosomes-enriched fractions,but not in exosomes-depleted serum(EDS).lncRNA TBILA,AGAP2-AS1 and SOX2 OT were screened out for the higher levels in NSCLC patients compared with those in healthy controls by two independent sets.The levels of TBILA were significantly correlated with tumor size,while AGAP2-AS1 levels were significantly correlated with lymph node metastasis and TNM stage.There was no significant relationship between SOX2 OT levels and clinical characteristics.Furthermore,RNase treatment and room temperature incubation did not reduce the levels of TBILA and AGAP2-AS1 evidently.Individual TBILA or AGAP2-AS1 exhibited better diagnostic efficiency in NSCLC patients with different tumor pathologic subtypes and early stage,whereas the combination of lncRNAs did not provide better results than individual lncRNAs.Notably,the combination of two exosomal lncRNAs and the serum tumor biomarker Cyfra21-1 widely used in clinical practices further improved the diagnostic accuracy for NSCLC patients.Conclusion: Serum exosomal lncRNA TBILA and AGAP2-AS1 are highly expressed in patients with NSCLC.These exosomal lncRNAs have better diagnostic efficiency and may be promising biomarkers for diagnosis of NSCLC.The combination of these exosomal lncRNAs and Cyfra21-1 could improve diagnostic efficiency for NSCLC. |
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