Clinical Significance And Cell Function Of PDZRN4 Experssion In Gastric Cancer

Gastric cancer(GC)is a kind of malignant digestive tract tumor,which seriously threatens the life safety of patients because of its low early screening rate,high clinical morbidity and mortality.The main treatment of GC is radical gastrectomy combined with radiotherapy and chemotherapy,but the prognosis of patients is seriously affected by factors such as body injury caused by resection,easy resistance of malignant tumors to chemotherapeutic drugs and so on.Nowadays,clinical treatment needs more suggestions of adjuvant therapy,and molecular targeted therapy has become a hot spot.It has been previously found that Numb ubiquitinated degradation of Notch receptors in zinc finger structure is involved in the regulation of tumor signal pathway.PDZRN4,which contains zinc finger domain,is a ligand of Numbprotein-X4(LNX4),which is a potential inhibitor of breast cancer(BC),liver cancer(HCC)and rectal cancer(READ).The role of zinc finger domain in GC is not clear.Therefore,this paper analyzed the differential expression of PDZRN4 based on TCGA database and 35 clinical samples,predicted the effect of PDZRN4 on the occurrence and development of GC and explored the cell function.First of all,the bioinformatics analysis of PDZRN4 gene was carried out in this paper.According to the(STAD)RNASeq data of gastric adenocarcinoma in TCGA database,there were 415 STAD samples and 35 normal samples.The results showed that the expression of PDZRN4 gene in normal tissues was 14.8 times higher than that in STAD tissues.Mi RNASeq and methylation data were downloaded at the same time,including389 STAD samples and 49 normal tissues.The results showed that the gene was down-regulated by has-mir-182 and methylation inhibition in STAD tissues,and there were four methylation sites;cg15417244,cg22501388,cg21926708 and cg16896079.The gene interaction and protein interaction network with PDZRN4 as the core was drawn by Coexpedia and DAVID data,and 55 genes and 10 interaction proteins were found.Results it is speculated that PDZRN4 participates in a variety of molecular regulatory networks to affect the carcinogenesis and development of gastric cancer,in addition to participating in Notch signal pathway with SORBS1 and FZD7,it may also be involved in Wnt and MAPK signal pathway.To sum up,it is predicted that PDZRN4 may be a potential tumor suppressor in gastric cancer.Then the relative expression of PDZRN4 in 35 STAD fresh tissue samples and normal gastric tissues was evaluated.Semi-quantitative polymerase chain reaction showed that PDZRN4 was down-regulated in 23/36(63.89%)STAD samples,and the content of PDZRN4 in STAD samples was 2.58 times higher than that in normal gastric tissue samples,which was consistent with the trend of TCGA RNASeq analysis.Finally qRT-PCR and WesternBlot were used to detect the expression of PDZRN4 in gastric cancer cell lines.AGS,a cell line with low expression of PDZRN4,and SGC7901,a cell line with high expression of PDZRN4,were screened and PDZRN4 overexpression and interference experiments were carried out respectively.48 hours after transfection of pc DNA3.1-PDZRN4 plasmid into AGS,the protein expression of the experimental group with overexpression of PDZRN4 was 4.46 times higher than that of the control group transfected with unloaded plasmid.At the same time,si RNA interference was carried out on PDZRN4 in SGC7901,and the interference efficiency was selected as 62%si PDZEN4-858 to continue the follow-up cell function experiment.Finally,the results of the functional study of PDZRN4 in GC cells showed that:(1)overexpression of PDZRN4 significantly inhibited cell proliferation,knockdown PDZRN4 could significantly improve cell proliferation;(2)overexpression of PDZRN4 could not significantly reduce apoptosis,knockdown PDZRN4 accelerated the process of apoptosis;(3)Migration,invasion and scratching experiments showed that high expression of PDZRN4 could inhibit cell movement,while low PDZRN4 could enhance cell migration and invasion.In a word,the results of this study show that PDZRN4 is a tumor suppressor gene in GC,which provides a theoretical and experimental basis for this gene as a new target in GC therapy.