| In clinical practice,lack of effectively detected methods in early stage,result in poor prognosis of most patients because of gastric cancer(GC)invasion and metastasis in advanced stage,Tumor metastasis is the main cause accounting for the poor prognosis.What's more,the molecular mechanism involved in the progression and metastasis of GC remains unknown.So,suitable diagnostic markers for cancers are urgently required in clinical practice.Long non-coding RNAs(lncRNAs),which have been reported in many cancer types,are a potential new class of biomarkers for tumor diagnosis.In my study,lncRNA gene expression profiles were analysed in two pairs of human GC and adjacent non-tumor tissues by microarray analysis.Nine gastric cancer-associated lncRNAs were selected and assessed by quantitative real-time polymerase chain reaction(q RT-PCR)in gastric tissues,and five of them were further analyzed in GC patients' plasma.We determined that five lncRNAs,including AK001058,INHBA-AS1,MIR4435-2HG,UCA1,and CEBPA-AS1 were validated to be increased in gastric cancer tissues.Furthermore,we found that plasma level of these five lncRNAs were significantly higher in GC patients compared with normal controls.By receiver operating characteristic(ROC)analysis,we found that the combination of plasma lncRNAs(AUC :0.921)including AK001058,INHBA-AS1,MIR4435-2HG,and CEBPA-AS1,is a better indicator of GC than their individual levels or other lncRNA combinations.The relationship between lncRNA levels in tissues and the clinicopathological features of GC patients was also analyzed.The expression levels of INHBA-AS1,MIR4435-2HG,CEBPA-AS1,and AK00108 were associated with tumor grade,AK001058 had a higher expression level in GC tissueswith lymph node metastasis compared to that with no lymph node metastasis and the expression level of UCA1 was higher in GC I stage than that in GC II-IV stage.For GC plasma,the expression level of INHBA-AS1 was associated with tumor sizeand tumor grade.There is a correlation between the expression level of AK001058 and depth of tumor invasion TNM stage.We also found that Correlation of lncRNAs expression and their antisense RNAs expression in gastric cancer tissues had a positive relatationship.Simultaneously,we found that the expression levels of a series of MIR4435-2HG fragments are different in GC plasma samples,but most of them higher than that in healthy control plasma samples.Taken together,Our results demonstrate that certain lncRNAs,such as AK001058,INHBA-AS1,MIR4435-2HG,and CEBPA-AS1,are enriched in human gastric cancer tissues and significantly elevated in the plasma of patients with GC.These findings indicate that the combination of these four lncRNAs might be used as diagnostic or prognostic markers for GC patients.At the same time,we also clarified that one group of lncRNAs,which are antisense in orientation to protein coding genes and are associated with human carcinogenesis,have been recently described in cancers but are poorly understood.We sought to identify antisense RNAs involved in human GC and to elucidate their mechanisms of influence in carcinogenesis and metastasis.Here,we validated 49 gastric cancer tissues and adjacent non-tumor tissues,and 88 GC plasma samples and77 healthy controls with age and sex matched by quantitative real-time polymerase chain q RT-PCR.And we detected that ZEB1 antisense RNA1(ZEB1-AS1)levels in tissues and plasma were significantly higher in GC patients(P<0.0001),respectively.The receiver operating characteristic curves(ROC)for ZEB1-AS1 in tissue and plasma were calculated,the area under the curves(AUCs)were 0.898 and 0.750,respectively.The relationship between lncRNA levels in tissues and the clinicopathological features of GC patients was also analyzed,ZEB1-AS1 had a higher expression level in GC tissues with lymph node metastasis compared to that with no lymph node metastasis(P=0.0486),and ZEB1-AS1 had a higher expression level in GC plasma with low tumor grade(P=0.0013).Furthermore,functional studies revealed that overexpression of ZEB1-AS1 could promote GC cells migration and invasion by upregulating the protein level of c-met and the phoshorylation level of ERK1/2.These datas suggest that ZEB1-AS1 could function as an oncogene to regulate the metastasis of GC,and high ZEB1-AS1 level could serve as a potential biomarker for the prognosis or the therapeutic target of GC.The main provements:1.LncRNAs are dysregulated in GC with gastric tissue microarray analysis.2.INHBA-AS1,MIR4435-2HG,CEBPA-AS1,and AK001058 were increased in GC tissues and plasma,detected by q RT-PCR,which could a biomarker for the prognosis of GC.3.LncRNA AK001058 had a higher expression level with lymph node metastasis and low tumor grade,it may promote the progress anfd metastasis of GC.And UCA1 could be used as a biomarker for the prognosis of GC at early stage because of its higher expression level in GC tissues at early stage.4.Plasma lncRNAs exist mainly in the form of RNA fragments,different fragments of MIR4435-2HG have different expression levels in GC plasma and healthy controls,and the same fragment has different levels in GC plasma and healthy controls.5.There is a positive relatationship.Between lncRNAs expression and their antisense RNAs expression in GC tissues,antisense RNA may function as a regulator for corresponding gene expression.6.LncRNA ZEB1-AS1 were increased in GC tissues and plasma,which could a biomarker for the prognosis of GC.7.ZEB1-AS1 had a higher expression level in GC tissues with lymph node metastasis compared to that with no lymph node metastasis,upregulation of ZEB1-AS1 could promote GC metastasis.8.Overexpression of ZEB1-AS1 could promote GC cells proliferation.9.ZEB1-AS1 particpated in the EMT progress of GC cells.10.It is the first to clarify that c-met could be a target for lncRNA ZEB1-AS1 to participate in the EMT progress of GC cells.It is a novel mechanism for ZEB1-AS1 as an oncogene in GC cells.Taken together,this study is the first to clarify that INHBA-AS1,MIR4435-2HG,CEBPA-AS1,and AK001058 were increased in GC tissues and plasma,combination of the four lncRNAs could be a biomarker for the prognosis of GC,with high sensitivity and specificity.We determined that Plasma lncRNAs exist mainly in the form of RNA fragments at the first time,maybe there is novel mechanism by which lncRNA fragments could be protected or degradated in plasma.At the same time,That ZEB1-AS1 was increased in GC tissues and plasma was clarified at the first time.As a metastasis-associated oncogene,ZEB1-AS1 could increase the protein level of c-met regulating the EMT progress of GC cells by interacting with c-met protein.According to the results we identified that lncRNAs play an important role in the progress and metastasis of GC,and they could be used as a novel biomarker for the prognosis and therapeutic target of GC. |
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