Downregulation Of LINC00673 Promotes Tumor Proliferation Via Repression Of HNF1A In Human Pancreatic Ductal Adenocarcinoma

Background:Pancreatic cancer(PC)has an abnormally high mortality rate [1][2],and has the worst consequence of all cancers [3].Only approximately 4% of those with PC survive 5 years after a PC diagnosis [4] and only about 10–20% of PC patients are candidates for surgery[5].PC is prone to rapidly invade ambient organs and demonstrates early metastatic transmission [6].In tumourigenesis,long non-coding RNAs(lnc RNAs)have essential roles [7].A number of studies have posited that the disorders of lnc RNAs are directly linked to human illnesses,including various types of cancers [8].Long intergenic noncoding RNA 673(LINC00673)is a type of long non-coding RNAs that is expressed differently in normal pancreatic tissues than in pancreatic ductal adenocarcinoma(PDAC)tissues.LINC00673 was a crucial role in non-small cell lung cancer(NSCLC)[9].Analysis of approximately 7000 recently genotyped individuals within the PC CaseControl Consortium authenticates a novel locus at 17q25.1(rs7214041 of LINC00673;the value of OR was 1.38;the value of P was 1.95 × 10-10),markedly related with a PC hazard using genome-wide association study [10].Moreover,Haplo Reg v2 also indicates that rs7214041 alters regulatory motifs for HNF1 A and a recent study of the pancreatic cancer transcriptome suggests that HNF1 A may act as a tumor suppressor in pancreatic cancers [10-12].We predicted that the probabilities interaction of linc00673 and HNF1 A via RNA-Protein interaction prediction website(RPISeq)[13].The probabilities interaction of LINC00673 with HNF1 A was 0.9 using RF classifier,however,it was 0.73,using SVM classifier,respectively.Furthermore,variant in HNF1 A is identified as risk factors for pancreatic cancer in pathway-based and candidate SNP–based analyses of the Pan Scan data [14][15].However,the significance of LINC00673 in the potential prognosis of PDAC is unclear.In this study,we aimed to evaluate the expression of LINC00673 and itsclinical association with PDAC.Then,we explored the potential value of LINC00673 in prognosis of PDAC and the mechanism.Methods:LINC00673 were validated using q RT-PCR in 51 cases of PDAC and 23 cases of adjacent pancreatic tissues.Moreover,the value of LINC00673 was confirmed by constructing a survival curve and a receiver operating characteristic(ROC)curve.In addition,EDU and CCK-8 were used to cell proliferation.Finally,the si RNA of LINC00673,Western blotting and qRT-PCR were used to the exploring the mechanism.Results:LINC00673 was downregulated in PDAC tissues,and its level was significantly downregulated in three PDAC cell lines in comparison with HPDE cell line.Low expression of LINC00673 was relevant to larger diameters,higher incidences of lymphatic metastases and poor differentiation.However,there were no close pertinences with egender,age,T classification,and neural invasion(P > 0.05).In addition,patients with low LINC00673 expression had a poor overall survival compared with the high LINC00673 group by Kaplan-Meier survival analysis.Moreover,we examined the impact of knockdown of LINC00673 in Ca Pan-1 and Hs-766 T cells.As shown in Figure3 A,48 h after transfection of the si RNA of LINC00673,qRT-PCR revealed that the expression of LINC00673 was significantly reduced in Ca Pan-1 and Hs-766 T cells.After transfection,CCK-8 and EDU were conducted.Transfection with the si RNA resulted in a significant increase in CaPan-1 and Hs-766 T cells viability and proliferation(Figure 3B;Figure 4;Figure 5).Next,results indicated that HNF1 A mRNA was downregulated in PDAC tissues and the expression level of HNF1 A mRNA was positively correlated with LINC00673 in these samples(Pearson ’ s correlation coefficient r = 0.469;P = 0.001;Figure 2C).In addition,q RT-PCR analyses showed that knockdown of LINC00673 could suppress expression level of HNF1 A m RNA(Figure 3A).Importantly,western blotting analyses showed that knockdown of LINC00673 could suppress expression level of HNF1 A and activate expression levels of phospho-AKT(Ser473)and phospho-m TOR(Ser2448)(Figure 6).Taken together,these results showed that knockdown of LINC00673 could promote tumor growth of PDAC cells via repression of HNF1 A.Conclusion:We first identified that PDAC patients with low LINC00673 expression had a poor overall survival.These results reveal that LINC00673 may serve as a potential tumor suppressor for prognosis of PDAC patients.