The Effect Of Replicator Factor-C4 Expression On The Clinicopathological Features Of Lung Adenocarcinoma And Its Possible Mechanism Of Dysregulation

Objective:The aim of our study was to explore the effects of replicator factor-C4 expression on the clinicopathological features of lung adenocarcinoma and its possible mechanism of dysregulation,which provides a theoretical basis for new therapeutic targets for lung adenocarcinoma.Methods:To explore whether the expression of replication factor C4(RFC4)in lung adenocarcinoma tissues is significantly different from that in adjacent tissues,RFC4-related data,including gene copy number variation(CNV),gene expression,DNA methylation data and clinical information,were obtained by GEPIA,CCLE and UCSC Xena website.Then,the map of RFC4 mRNA were made by GraphPad Prism and R language software or on line.Secondly,we use R language and GraphPad Prism to extract and analyze the data related to RFC4 in order to explore the influence of different expression of RFC4 on clinical pathological characteristics in lung adenocarcinoma.Then,Based on the expression of RFC4 protein was semi-quantitatively analyzed by immunohistochemical assay,and the effect of different expression of RFC4 on clinical pathological characteristics was verified at the protein level.Finally to explore the imbalance mechanism of the expression of RFC4,the relevant data of RFC4,gene CNV,methylation,gene mutation and RFC4 mRNA will be visualized through heat map by UCSC Xena website for seek the cause of up-regulation of RFC4 mRNA,then using linear correlation analysis to verify the above-mentioned related factors(positive correlation only with gene copy variation),and then obtained the Co-expression genes of RFC4 which were conducted to the KEGG pathway enrichment analysis and GO Molecular Function analysis on line for exploring the possible molecular mechanism of increased CNV.Results:RFC4mRNA was over expressed in various cancer tissues,including lungadenocarcinoma,and the expression of RFC4 mRNA in lung adenocarcinoma tissues was significantly higher than that in adjacent tissue.The mortality and lymph node metastasis rate of patients with lung adenocarcinoma with overexpression of RFC4 mRNA were significantly higher than those with low expression(all P < 0.05).Patients with overexpression of RFC4 mRNA not only had a significantly shorter median overall survival time(50%OS)than those with low expression of RFC4 mRNA,but also in median relapse-free survival time(50%RFS).(overexpression of RFC4mRNA:50%OS: 54.4±5.34 m,50%RFS: 68.17±14.07m;low expression of RFC4mRNA:50%OS: 41.9±3.65 m,50%RFS: 38.9±9.55m)(P <0.05).COX risk proportional regression model analysis also showed that overexpression of RFC4 mRNA was not only an independent risk factor for poor OS,but also an independent risk factor for poor RFS in lung adenocarcinoma(all P<0.05).The effect of different expression of RFC4 protein on clinical pathological characteristics of lung adenocarcinoma was basically consistent with the above results:The mortality rate and lymph node metastasis rate of patients with lung adenocarcinoma with overexpression of RFC4 protein were significantly higher than those with low expression of RFC4 protein(all P < 0.05).The median survival time of those with overexpression of RFC4 protein was significantly shorter than that of those with low expression of RFC4 protein.The median survival time of those with low expression of RFC4 protein was 53.5 ± 6.23 m,while that of those with overexpression of RFC4 protein was only 45.50 ± 1.84 m.COX proportional risk regression model analysis also showed that overexpression of RFC4 protein was an independent risk factor for poor OS in lung adenocarcinoma,and the risk of death in the overexpression expression group was 1.94 times higher than that in the low expression group(P<0.05).The up-regulation of RFC4 gene expression was positively correlated with the amplification of copy number variation,but not with methylation or gene mutation(P < 0.05).The specific molecular mechanism of the increase of gene copy number variation may be related to cell cycle pathway,DNA replication and other signaling pathways,microtubule binding,cathepsin activity and othermolecular functions(P < 0.05).Conclusions:RFC4 is up-regulated in lung adenocarcinoma,which is associated with poor prognosis of lung adenocarcinoma.It can be used as a molecular marker for the prognosis of lung adenocarcinoma.RFC4 may be involved in the cancer-promoting effect of lung adenocarcinoma mainly through cell cycle,DNA replication signaling pathway,microtubule binding and group protease activity molecular function.