LncRNA-AK055783 Promotes Cell Proliferation And Invasion Of Gastric Cancer By Regulating ERBB2/PI3K/AKT Signaling Pathway

Background: Gastric cancer is one of the most frequently occurring malignancies with high morbidity and mortality worldwide.Despite progresses in diagnosis and treatment of gastric cancer,the prognosis of gastric cancer remained poor.Because of high rate of recurrence and metastasis of gastric cancer,the five-year overall survival rate in patients was less than 20%.Therefore,it is urgent to investigate the pathogenesis and treatment of gastric cancer.Long non-coding RNA(lncRNA)is a kind of RNA molecule longer than 200 nucleotides,which is not directly translated into protein or involved in protein synthesis.Recent evidence suggested that lncRNA controls a variety of biological processes,such as cell proliferation,apoptosis,invasion,and migration,and participates in human disease pathogenesis.Aberrant expression of lncRNA is associated with various tumors,such as ovarian cancer,colorectal cancer,prostate cancer,and breast cancer.However,the literatures regarding lncRNA in gastric cancer are still limited.Therefore,it is necessary to search gastric cancer-specific expressing lncRNA and further to explore their functions and mechanisms,thereby exploring novel molecular mechanisms of gastric cancer.Methods: Along with the extensive development of the expression array technology,there are numerous and complicated biological information data.Data of current study is derived from GSEA and GCBI analysis,which screened out the significantly different expressed lnc RNAs in gastric carcinoma.RT-PCR then was used to detect candidate lncRNAs in tissue for selection of the target lnc RNA in further investigation.And then the association between lncRNA and clinical pathological features of gastric cancer was analyzed.Knock-down and overexpression of lncRNA were performed by constructing lentivirus-shRNA and overexpression lentivirus.Then,the influence of knock-down or overexpression of lncRNA on the biological behavior in gastric cancer cell lines and in vivo mouse model were explored.Finally,RNA-IP and RNA pull down assay were applied to identify the binding protein and signaling pathway linked to this lncRNA.Results: Our results showed that lncRNA-AK055783 was screened as the significantly differentially expressed lnc RNA through bioinformatics analysis;wihch was further validated to be higher expressed in gastric cancer by RT-PCR.LncRNA-AK055783 expression were detected in five gastric cancer cell lines,including MGC803,BGC823,SGC7901,MKN45 and AGS,with the lowest expression level in MGC803 and the highest expression level in MKN45.Based on the median expression level of lncRNA-AK055783 in 46 cases of clinical gastric cancer tissues and paired adjacent normal tissues,patients were divided into higher expression group and lower expression group.There are significant correlation between expression of lncRNA-AK055783 and T(χ2=5.275,p<0.05)N(χ2=4.546,p<0.05)M stage(χ2=4.305,p<0.05)of gastric cancer.Patients with higher expression level of lncRNA-AK055783 have a shorter overall survival time(p=0.0109,Mantel-Cox Test).MGC803 and MKN45 cells were transfected via knockdown and overexpression lentivirus vectors of lncRNA-AK055783.MTT experiments,clone formation assay,and the invasion assay showed that the decreasing expression of lncRNA-AK055783 inhibited proliferation and invasion of gastric cancer cells in vitro.Meanwhile,xenograft model demonstrated that knocking-down of lncRNA-AK055783 inhibited tumor growth,node metastasis and distant metastasis,while overexpression of lncRNA-AK055783 could promote tumor growth,node and distant metastasis.RNA-IP and RNA pull-down assay showed that lncRNA-AK055783 directly binds ERBB2.After overexpression of lncRNA-AK055783 in MGC803 and MKN45 cells,we found that ERBB2 protein was significantly up-regulated and ERBB2 luciferase activity was enhanced,but ERBB2 mRNA was not significantly changed.In addition,PI3K/AKT signal pathway was downregulated when knocking down lnc RNA-AK055783,and upregulated after overexpression of lncRNA-AK055783 by Western Blot.These results indicated that lncRNA-AK055783 can activate the PI3K/AKT signal pathway through binding with ERBB2,promote proliferation and invasion of gastric cancer.Conclusion: lncRNA-AK055783 could promote proliferation and invasion of gastric cancer via post-transcriptionally regulating ERBB2 expression and activating ERBB2/PI3K/AKT signaling pathway.