Clinical Significance Of Dysregulated Long Noncoding RNAs KRT18P55,CTC-501O10.1,AC100830.4 And RP11-210K20.5 In Gastric Cancer

Objective: Gastric cancer(GC)is one of the most common diagnosed cancers throughout the world.In general,incidence rates are highest in Eastern Asia.Although chemotherapy,radiotherapy and surgery remain as the primary treatments for GC,the 5-year overall rate for GC patients is still less than 25% because of recurrence and metastasis.Hence,it is important to identify highly sensitive and specific cancer-related novel biomarkers,which can contribute to improve prevention,detection,diagnosis and treatment of GC.Long noncoding RNAs(lnc RNAs)are a significant new class of transcripts longer than 200 nucleotides.To date,growing evidence has indicated that lnc RNAs acting as potential biomarkers are associated with the development of numerous cancer types.Therefore,we aimed to discover and explore novel lnc RNAs which exclusively expressed in GC tissue or plasma and act crucial roles in clinical practice.Methods: For the first section of our research,based on the microarray and cluster analyses of six pairs GC tissues and matched normal adjacent tissues(NATs),differentially expressed lnc RNAs were identified.We tested these dysregulated lnc RNAs in GC cell lines(SGC-7901,MGC-803,BGC-823,HGC-27 and AGS)by using quantitative polymerase chain reaction(q PCR).The lnc RNAs with consistent relative expression between the results of microarray and GC cell lines become the alternatives.In addition,we also test the relative expression of the alternative lnc RNAs in 97 pairs of GC tissues by using q PCR.The expressions of alternative lnc RNAs were also combined with the clinicopathological and prognostic information of GC patients to further explore clinical significance of these alternatives.Moreover,The Cancer Genome Atlas(TCGA)datasets was also used to verify aforementioned analyses.Finally,receiver operating characteristic(ROC)was constructed to test the value of alternatives in discriminating tumor tissues from nontumorous tissues.For the second section of our research,we used plasma samples from 4 GC patients and healthy controls to conduct microarray analyses to explore significant dysregulated circulating lnc RNAs.In the discovery phase,the top 15 differentially expressed lnc RNAs were identified for further analysis in the next phase.In the testing phase,candidate lnc RNAs were analyzed in another 20 GC patients with matched healthy controls and in cell lines and culture media via q PCR.Consistently dysregulated lnc RNAs were further investigated in the training phase,using 100 GC patients with matched healthy controls.A combination of several lnc RNAs was selected as a panel of GC diagnostic markers using a stepwise model selection method according to the q PCR results.In the validation phase,the diagnostic values of the plasma lnc RNAs were estimated in another 50 GC patients with matched healthy controls,and correlations between the lnc RNA expression levels and the clinicopathological parameters of the patients were examined.Statistical analyses were performed by SPSS and Stata software,two-tailed P values < 0.05 were considered to be statistically significant.Results: For the first section of our research,KRT18P55 is a novel upregulated lnc RNA with consistent results of tissues-based microarray and verification in GC cell lines.In addition,based on our GC patients and TCGA datasets GC patients' cohort,KRT18P55 showed significant high expression in GC tissues in comparison with NATs(P < 0.01).Meanwhile,the expression level of KRT18P55 was associated with the incidence of Lauren intestinal-type GC(P < 0.01).We did not observe a significant relationship between KRT18P55 and survival of overall GC patients.Moreover,KRT18P55 could be a biomarker in discriminating tumor tissues from nontumorous tissues with an AUC of 0.733 in our hospital cohort(P < 0.01).For the second section of our research,from the results of plasma-based microarray analyses,we found three novel lnc RNAs CTC-501O10.1,AC100830.4,and RP11-210K20.5,which are upregulated in GC cell lines,culture media and 20 pairs of GC plasma samples.In the training phase,CTC-501O10.1,AC100830.4,and RP11-210K20.5 were upregulated in the plasma of overall 100 GC patients with AUCs 0.724,0.730,and 0.737,respectively(P < 0.01).In addition,in the subgroup of early GC patients,the AUCs of these three lnc RNAs were 0.739,0.761 and 0.752,respectively(P < 0.01).Based on the logistic regression model,the combined AUC of the three lnc RNAs is 0.764 in the overall cohort(P < 0.01).However,in the validation phase,the results indicated that the panel could provide an AUC of 0.700 to distinguish GC from healthy controls based on the logistic regression model from the training phase.There were no significant correlations observed between the expression levels of the lnc RNAs and the clinicopathological characteristics of the GC patients.Conclusion: KRT18P55 is upregluated in GC tissues and its expression is associated with Lauren classification significantly.In addition,circulating lnc RNAs CTC-501O10.1,AC100830.4,and RP11-210K20.5 are upregulated in GC plasma with AUCs 0.724,0.730,and 0.737,respectively.The combined AUC of the three lnc RNAs is 0.764 in the overall cohort.Large scale case and multicenter investigations are still necessary before this can expand to clinical practice.