| Objective:Gastric cancer(GC)remains the fourth most commonly malignant tumor,with a high mortality rate worldwide.Due to developing early detection and improving surgery treatment,the overall survival of patients with gastric cancer has gradually improved.However,with a lack of early specific clinical symptoms of gastric cancer,many patients are diagnosed at advanced stages with over metastasis,losing the best chance for curative surgery.Thus,the search for new effective biomarkers is still essential for early diagnosis of gastric cancer.Gene expression data is now becoming accumulated in astronomical speed.Several databases have been developed.A large number of dysregulated genes in gastric cancer have been identified,and the detailed functions of those genes studies have been carried out.This includes studies of Long-non-coding RNA(IncRNA)in gastric cancer.However,how do these Long-non-coding RNAs regulate related gene expression and participate in the regulation of tumor proliferation,invasion,apoptosis and other processes.It has not yet been fully found.LncRNA is a kind of RNA lacking of coding potential,with its transcript length more than 200 nucleotides.Comprehensive analysis of LncRNA expression in multiple human organs shows that LncRNAs display more tissue-specific expression patterns than protein-coding genes.It has an important impact on the process of growth and death.In addition,LncRNA is also involved in the regulation of a variety of pathological and physiological processes.The mechanism of LncRNA is complicated,and it can regulate gene expression at the level of epigenetics,transcription or posttranscription.Recently evidence suggested that aberrant expression of Inc RNA have been found in tumor tissues,such as gastric cancer,ovarian cancer,lung cancer,colorectal cancer,liver cancer,prostate cancer,and breast cancer.In this study,based on a public available databases:the NationalCenter for Biotechnology Information Gene Expression Omnibus(NCBI-GEO),we screened out the significantly different expressed LncRNAs in gastric cancer.Then,we study its function and mechanism.The whole experiment is divided into three parts:Methods and ResultsThe first part:the difference of LncRNA expression in gastric cancer,In GSE84787 datasets,83 differentially expressed IncRNAs(|Fold Change|>2,p<0.05)were identified including 7 downregulated IncRNAs and 76 upregulated by using the limma package in R software.Similarly,differentially expressed genes including 70 miRNAs(66 downregulated and 4 upregulated)and 4359 mRNAs(1362 downregulated and 2997 upregulated)were screened from GSE93415 and GSE79973,respectively.Volcano plot was used to visualize aberrantly expression between tumor group and non-tumor group.The interactions between differentially genes(miRNA,lncRNA,miRNA and mRNA)were predicted by using DIANA-LncBase v2 and mirtarbase.LUCAT1,hsa-miR-24-3p and IGF1R or KRAS were the IncRNA,miRNA and mRNA with the largest degree in the network separately,indicating that they were significant genes in the regulatory network.The second part:Verify gastric cancer related IncRNA.The expression levels of LUCAT1 and LACTB2-AS 1 from 70 GC and paired adjacent normal specimens were detected by qRT-PCR verification.The results revealed that LUCAT1 and LACTB2-AS1 were both obviously upregulated in GC tumor tissues compared with adjacent normal tissues.So in the next study,we focus on clinical characteristics of LUCAT1 and LACTB2-AS1 in gastric cancer.High expression levels of LUCAT1and LACTB2-AS1 were associated with aggressive and advanced cancer.Increased expression of LUC ATI associated with tumor diameter,tissue differentiation grade and lymphatic metastasis,while LACTB2-AS1 was related to age,tumor diameter,and invasion.These results clearly showed that high expression levels of LUCAT1 and LACTB2-AS1 were associated with aggressive and advanced cancer.However,we did not find any association between these IncRNA expression levels and other clinicopathological factors including gender,distal metastasis and TNM stage.To evaluate the potential diagnostic values of these LncRNAs,the ROC curves were conducted to determine respective optimal cutoff values.The cutoff values for LUCATland LACTB2-AS1 were 5.4 and 4.3.As for LUCATI,its AUC was up to 0.845.and the sensitivity and specificity was 85.7 and 71.4%,respectively.The Youden index was 0.571.AUC of LACTB2-AS1 was up to 0.845.The sensitivity and specificity was 74.2 and 87.1%,respectively.The Youden index was 0.613.As a IncRNA firstly found in the airway epithelium of cigarette smokers,lung cancer associated transcript 1(LUCATl)is considered to be a poor prognostic factor in human non-small cell lung cancer,regulating cell proliferation via epigenetically repressing p21 and p57 expression.Recent studies demonstrate that LUC ATI also promotes tumorigenesis in esophageal squamous cell carcinoma,glioma and clear cell renal cell carcinoma.According to the results of the chip and the expression of Lnc RNA in tumor samples,LUC ATI may play an important role in the development and progression of gastric cancer.The third part:the effect of LUCAT1 on tumor cell biology.Real-time fluorescence quantitative PCR assays showed that the expression of LUC ATI in gastric cancer cell lines was significantly higher than that in normal gastric epithelial cell lines,and gastric cancer cell line SGC-7901 has the highest expression,AGS gastric cancer cell line has the lowest expression.To explore the function of LUCAT1,we conducted cell experiment.The expression of LUCAT1 in AGS and SGC-7901 was knocked down by constructing lentivirus.Then,the influence of knock-down of LUCAT1 on the biological behavior in cell proliferation,apoptosis,migration,invasion,cell cycle and tumor growth was explored in AGS and SGC-790 cells.The proliferation of LUCAT1 knockdown gastric cancer cells was conducted by CCK-8.It showed that the proliferation of the AGS and SGC-7901 cells in the LUCAT1 knockdown group was significantly decreased.Formation of colonies showed that when the expression level of LUCAT1 was downregulated,colony formation rate was inhibited.Flow cytometry results showed that the decreasing expression of LUCAT1 promoted cell apoptosis.The wound healing scores and transwell assay showed that the experimental group was lower than control group,LUC ATI promoted the migration of AGS andSGC-7901 cells.The transwell experiments with matrix showed that LUCAT1 can enhance the invasion of AGS and SGC-790 cells.CCK-8 experiments,colony formation,apoptosis,wound healing,transwell assays showed that the decreasing expression of LUC ATI significantly inhaited proliferation,migration and invasion,promoted cell apoptosis.LUCAT1 plays an oncogene role in the development of gastric cancer.The detection of the expression level of LUC ATI is of potential value to the prognosis of patients with gastric cancer.ConclusionHere,we found that LUCAT1 and LACTB2-AS1 significantly expressed in the tumor tissues of gastric cancer patients with 0.70 pairs of matched gastric cancer tissues and adjacent tissues to verify the differential expression of lncRNA,and the expression difference was up-regulated;related statistical methods found that the expression levels of LUCAT1 and LACTB2-AS1 were significantly correlated with age,tumor diameter,depth of invasion,tumor diameter,degree of tissue differentiation and lymph node metastasis,and had certain diagnostic value for gastric cancer;LUCAT1 also showed sputum expression in cell lines,and the results of cell experiments showed that LUCAT1 knockdown can effectively inhibit the proliferation,migration and invasion of gastric cancer cells,and promote the apoptosis of gastric cancer cells.The above results provide the diagnosis and treatment of gastric cancer.A new theoretical basis. |
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