The Correlation Between SPP1 And Immune Escape Of EGFR Mutant NSCLC Was Explored By Bioinformatics Analysis

Objective: In this study,the RNA-seq data set of patients with lung adenocarcinoma from the TCGA public database was used to analyze the effect of EGFR mutation on Tumor Microenvironment(TME)and its correlation with secreted phosphoprotein 1(SPP1)mediated immunosuppression.These methods provided a new idea for guiding clinical treatment.Methods:Differences in EGFR mutation rates among different clinical characteristics were analyzed by chi-square test or Fisher exact test.Wilcoxon rank-sum test was used to compare the differences in SPP1 expression between tumor and paracancerous tissues,as well as between EGFR mutant and wild-type patients.CIBERSORT was used to analyze 22 types of immune cells infiltration in patients with TCGA lung adenocarcinoma.Then we compared the differences on EGFR gene changes and SPP1 expression.In this study,R(version 3.4.3)and SPSS(version 26.0)were used for statistical analysis and plotting,with P<0.05 was considered statistically significant.Results:1.The relationship between EGFR gene mutation and clinical characteristics of patientsThe mutation rate of EGFR gene is different in gender.It is more likely to happen in females than males(P=0.002).There were no significant difference in EGFR mutant rate among patients with different age groups,races,TNM and Stages.No significant difference was observed in the rates of accompanied EGFR mutation between wild and mutated TP53 patients(P=0.184).The wild-type KRAS patients were more likely to have EGFR mutation than KRAS mutant patients,and the difference was statistically significant(P<0.001).2.Differences in the infiltration of 22 types of immune cells in tissues of EGFR mutant and wild-type NSCLCThe proportions of CD8+T cells(P<0.001),activated CD4+T cells(P =0.0017)and M1 type macrophages(P = 0.047)in tumor tissues of patients with EGFR wild type were higher.The proportions of resting memory CD4+T cells(P =0.0018),resting and activated dendritic cells(P =0.0065,P = 0.0096),and resting mast cells(P =0.0044)were higher in patients with EGFR mutation.3.Differences in SPP1 expression between EGFR mutant tissues and wild tissuesThe expression of SPP1 in tumor tissues were significantly higher than that in paracancerous tissues(P<0.001).The expression of SPP1 in the EGFR mutant group were higher than that in wild group(P=0.031).4.Differences in the infiltration of 22 types of immune cells in the groups with high and low SPP1 expressionThe proportions of resting NK cells(P=0.047),M0 macrophages(P <0.001),M2 macrophages(P= 0.0014),and neutrophils(P <0.001)were higher in the SPP1 high expression group than those in the low expression group.On the contrary,compared with the high expression of group,the SPP1 low expression group naive B cells(P = 0.025),memory B cells(P = 0.012),and CD8+T cells(P < 0.001),resting memory CD4+T cells(P = 0.019),follicular helper T cells(P = 0.039),activated NK cells(P = 0.033),activated dendritic cells(P = 0.0083),resting mast cells(P < 0.001)were higher proportion.5.Correlation analysis between SPP1 expression and the infiltration of different immune cellsSpearman correlation analysis was performed between SPP1 expression and the infiltration of different immune cells.It was found that the increased expression of SPP1 was negatively correlated with the infiltration of CD8+T cells(r=-0.374),central CD4+ memory T cells(r=-0.236),follicular helper T cells(r=-0.276),activated NK cells(r=-0.208)and activated dendritic cells(r=-0.157).It was positively correlated with macrophages(r=0.405),M2 type macrophages(r=0.285),and stationary dendritic cells(r=0.155).Conclusions:1.In the tumor microenvironment of patients with EGFR mutant lung adenocarcinoma,CD8+T cell infiltration was less and macrophage M2 polarization was more obvious in the tumor microenvironment.2.The expression of SPP1 in tumor tissues of EGFR mutant lung adenocarcinoma patients were higher than that of wild-type patients.3.In the group with high SPP1 expression,M2-type macrophages increased and CD8+T cells decreased.The high expression of SPP1 was positively correlated with the infiltration level of M2-type macrophages,while the infiltration level of CD8+T was negatively correlated.4.Immunosuppression in patients with EGFR mutation may be related to the high expression of SPP1.