Expression And Regulatory Role Of TRIM55/PDZRN4 Under Hypoxic Conditions In Gastric Cancer

Objective To observe the expressions of TRIM55/PDZRN4 in gastric cancer cells and tissues with its clinical significance,and to explore biomarkers associated with the tumor hypoxia microenvironment to provide a theoretical basis for the diagnosis and treatment of gastric cancer.Methods（1）In vitro cell-level assay,normal human gastric epithelial cell line GSE-1 and four gastric cancer cell lines with different differentiation（HGC-27,MN-45,NCI-N87,KATO-Ⅲ）were purchased,which were performed cell culture and identified by short tandem repeats（STR）typing technique.Moreover,the expression levels of TRIM55 and PDZRN4genes in different cell lines were showed using Reverse Transcription quantitative Polymerase Chain Reaction（RT-qPCR）assay and gene sequence confirmation.（2）gastric cancer cell line NCI-N87 was used as the research object to construct the cell hypoxia model.RT-qPCR assay were applied to detect the changes of TRIM55 and PDZRN4 genes expression levels in NCI-N87 after 24h and 48h of normoxia and hypoxic（3%O₂）culture.（3）Multiple online databases,such as UALCAN,GEPIA,LOGpc and Kaplan-Meier Plotter,were adopted to comprehensively analyze the differences expression and survival analysis of TRIM55 and PDZRN4 in gastric cancer patients.Results（1）Firstly,the quality of each cell line was verified by STR analysis.The expression of TRIM55 gene and PDZRN4 gene increased in different gastric cancer cell lines.（2）The expression levels of PDZRN4 gene and TRIM55 gene in gastric cancer cell line NCI-N87increased after 24h or 48h of normoxia culture;After 24h hypoxic culture,the expressions of PDZRN4 gene and TRIM55 gene were higher than those of normal culture group.After 48h hypoxic culture,the expressions of PDZRN4 gene and TRIM55 gene were higher than those of normal culture group,and the trend had significant changes.Under 24h hypoxic conditions,the expression level of PDZRN4 gene and TRIM55 gene in NCI-N87 cells was higher than that under normoxic culture conditions.Under 48h hypoxic conditions,the expression level of PDZRN4 gene and TRIM55 gene in NCI-N87 cells was significantly higher than that under normoxic culture conditions,and the trend had significant changes.（3）The mRNA expressions of TRIM55,PDZRN4 in gastric cancer tissues were lower than that in normal tissues using the UALCAN and GEPIA databases.（4）To investigate the association of TRIM55/PDZRN4 mRNA expression level with the prognosis of gastric carcinoma using the UALCAN and Kaplan-meier Plotter databases.It was found that high expression of TRIM55/PDZRN4 was related to a poor overall survival（OS）in gastric cancer patients.Meanwhile,the PDZRN4 was further confirmed in the TCGA,GSE84437 and GSE62254datasets of LOGpc database.Furthermore,an analysis of the GSE6225 dataset demonstrated that the increased-PDZRN4 expression group had poor disease-free survival（DFS）for gastric cancer patients.In addition,the progression free interval（PFI）was significantly shorter in gastric cancer patients with overexpression than low expression of TRIM55 in the TCGA of LOGpc database.According to the Kaplan-Meier Plotter database,the post progression survival（PPS）was significantly shorter in gastric cancer patients with overexpression than low expression of TRIM55,and the FP and PPS was significantly shorter in gastric cancer patients with overexpression than low expression of PDZRN4,the difference was statistically significant.Conclusion Our results demonstrated that the expressions of TRIM55 gene and PDZRN4 gene in gastric cancer cells were increased,but the expression of TRIM55 and PDZRN4 was lower in patients with gastric cancer than in healthy controls.TRIM55 and PDZRN4 may be potentially clinically related oncogene and tumor suppressor gene respectively,which may be involved in carcinogenesis and development of gastric cancer.Bioinformatics analysis results showed that high expression of TRIM55/PDZRN4 is associated with poor prognosis in gastric cancer tissues.Cellular assays initially validated that the malignant degree of gastric cancer cells was affected by regulating the expression of TRIM55 and PDZRN4 under hypoxia condition,suggesting that TRIM55/PDZRN4 may be a potential biomarker and therapeutic target for gastric cancer associated with hypoxia.