Screening of endoplasmic reticulum stress signature-related genes in gastric cancer and the establishment of prognostic risk models / 肿瘤研究与临床

ABSTRACT

Objective:To screen the endoplasmic reticulum stress (ERS) signature-related differentially expressed genes (DEG) in gastric cancer and to construct a prognostic risk model based on a bioinformatics.Methods:Transcriptome sequencing data (RNA-seq) of 375 gastric cancer and 32 paracancerous tissue samples downloaded from The Cancer Genome Atlas (TCGA) database and the corresponding clinical information were obtained as training set samples; data of 387 gastric cancer patients (GSE84437) from Gene Expression Omnibus (GEO) database were downloaded as validation set samples. All data were obtained on December 25, 2021. A total of 785 ERS signature-related genes (ERS-RG) were obtained from the GeneCards database. DEG between gastric cancer tissues and paracancerous tissues in the TCGA database was analyzed. The identified gastric cancer DEG were intersected with ERS-RG from the GeneCards database to obtain gastric cancer ERS signature-related DEG, which were analyzed for gene ontology (GO) function and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment. Univariate Cox proportional risk model was used to screen ERS signature-related DEG with prognostic value in gastric cancer, and LASSO regression analysis was performed to construct a polygenic prognostic risk model, and to calculate the prognostic risk score. The patients in training set and validation set were divided into high-risk group and low-risk group according to the median of the prognostic risk score (2.369); Kaplan-Meier survival analysis was used to compare the overall survival (OS) and to draw time-dependent receiver operating characteristic (ROC) curves of patients in the two groups; nomogram was drawn based on the prognostic independent influencing factors of gastric cancer. The characteristic immune cell infiltration abundance between the two groups was analyzed by using the inverse convolution-based CIBERSORT algorithm. Cytolytic activity scores were calculated by using the geometric mean of granzyme A and perforin 1 expression. According to the median prognostic risk score (2.369) and median tumor mutation burden (TMB) (3.000), all patients with gastric cancer were divided into high risk score-high TMB group, high risk score-low TMB group, low risk score-high TMB group and low risk score-low TMB group to compare the OS of patients in each group.Results:A total of 444 ERS signature-related DEG in gastric cancer including 168 down-regulated genes and 276 up-regulated genes were obtained, which were mainly enriched in biological processes such as protein processing in the endoplasmic reticulum, extracellular matrix (ECM) receptor interactions and unfolded protein responses (all P < 0.05). Univariate Cox regression analysis showed that 12 prognostic-related ERS signature-related DEG in gastric cancer were screened out. LASSO regression analysis was performed to obtain a prognostic risk score = 0.052×NOS3+0.137×PON1+0.067×CXCR4+0.131×MATN3+0.116×ANXA5+0.090×SERPINE1. The results of Kaplan-Meier analysis showed that the OS of the low-risk group in both the training and validation sets was better than that of the high-risk group (all P < 0.01). The results of the time-dependent ROC curve analysis showed that the AUC for the 3-year, 5-year, 8-year OS rates was 0.695, 0.786, 0.698, respectively in the training set, while the AUC for the 3-year 5-year, 8-year OS rates was 0.580, 0.625, 0.627, respectively in the validation set. Multivariate Cox regression analysis showed that prognostic risk score ( HR = 3.598, 95% CI 2.290-5.655, P < 0.001) and tumor stage ( HR = 1.344, 95% CI 1.057-1.709, P < 0.05) were independent factors influencing the prognosis of gastric cancer. Among 375 gastric cancer patients in the TCGA database, the expression levels of ATF6, HSPA5, XBP1 and ATF4 in the high-risk group were higher than those in the low-risk group (all P < 0.05); CIBERSORT results showed that the abundance of activated CD4 memory T cells in the high-risk group was lower than that in the low-risk group, and the abundance of both M0 and M2 macrophages in the high-risk group was higher than that in the low-risk group (all P < 0.05). The expression levels of common immune checkpoints (CD274, CTLA4, TNFRSF9, TIGIT, PDCD1, LAG3) in the high-risk group were all higher than those in the low-risk group (all P < 0.05). Cytolytic activity score in the high-risk group was higher than that in the low-risk group ( P < 0.05). The prognostic risk score was negatively correlated with TMB ( r = -0.20, P < 0.001). Patients in the low-risk score-high TMB group had the best OS and those in the high-risk score-low TMB group had the worst OS (both P < 0.001). Conclusions:The prognostic risk score model is established based on 6 ERS signature-related DEG in gastric cancer and its prognostic risk score may be effective as an independent prognostic factor to predict the prognosis of gastric cancer patients.