Identification Of A Novel Pyroptosis-Related Gene Prognostic Index And Evaluation Of Immune Infiltration Features In Uveal Melanoma

Objective Uveal melanoma(UM)represents the most common primary adult intraocular malignancy of which more than 90%are choroidal melanoma,and distant metastasis and refractory are the core issues.Pyroptosis is an kind of inflammatory programmed cell death distinct from apoptosis,necrosis,autophagy,and ferroptosis that affects anti-cancer immunity by regulating the infiltration of tumor immune cells.Yet,the role of pyroptosis in the prognosis of UM,tumor immune microenvironment,and immunotherapy remains unclear.This study aims to explore the prognostic value of pyroptosis in UM and its association with tumor microenvironment and immune infiltration,construct the prognostic index of pyroptosis-related genes(PRGPI),and evaluate the prognosis and immune response of patients.Methods First,the RNA-sequencing data and corresponding clinicopathological information of UM patients were downloaded from the Cancer Genome Atlas(TCGA)and Gene Expression Omnibus databases.Then,Cox regression analysis was used to select the intersection of prognostic related pyroptosis genes(PRGs)from UM samples of TCGA-UVM and GSE84976 datasets.Based on consensus clustering analysis of PRGs expression patterns,the tumor phenotype of UM and its differences in prognostic and immune infiltration characteristics were analyzed.The PRGPI was further constructed using Least absolute shrinkage and selection operator(LASSO)regression analysis on the TCGA-UVM training set,and externally validated with two other UM datasets(GSE84976,GSE22138).According to the median value of risk index,UM patients were divided into high-and low-risk subgroups.The prognostic value of PRGPI was assessed by Kaplan-Meier survival analysis,time-dependent receiver operating characteristic(ROC)curves,and Cox analysis.Combining PRGPI with clinicopathological parameters,a nomogram was established to predict 1-,2-,and 3-year overall survival(OS)in patients with UM.Differentially expressed genes(DEGs)were filtered in the TCGA-UVM cohort between two risk subgroups(|log2FC|≥1,FDR<0.05),and the biological functions involved in DEGs were analyzed by Gene Ontology(GO)、Gene Set Enrichment Analysis(GSVA),and Kyoto Encyclopedia of Genes and Genomes(KEGG)enrichment.In addition,the differences in pathological characteristics,tumor mutational burden(TMB),tumor microenvironment(TME),immune infiltration,tumor immune subtypes among risk subgroups were comprehensively analyzed through multi-omics.Immunophenoscore(IPS)(TCIA database)was used to verify the predictive ability of PRGPI for immune response in patients with skin cutaneous melanoma(SKCM).Results There were two different phenotypes in UM.Compared with cluster 1,cluster 2,which highly expressed high expression of PRGs,had woser prognosis and significant differences in immune cell infiltration.We successfully constructed PRGPI based on GSDMD,BAX and IRF1 expression.OS of high-risk subgroup was significantly lower than that of low-risk subgroup.The nomogram,which constructed with PRGPI and clinicopathological features,was able to robustly predict the OS of UM patients.DEGs in high-and low-risk subgroups were associated with immune and inflammatory signaling pathways such as T cell activation,INF-γresponse,antigen processing and presentation.High-risk subgroup had low TMB and tumor purity,high level of CD8~+T cells,activated memory CD4~+T cells and M1 macrophages infiltration.The low-risk subgroup had high immune score and interstitial score,high level of resting memory CD4~+T cells,resting NK cells,monocytes,and resting mast cells.In the high-risk subgroups,the inflammatory subtype was significantly increased.On the contrary,the low-risk subgroup was dominated by the subtype of lymphocyte depletion.We also found that the IPS score of high-risk subgroup was significantly higher,indicating that SKCM patients in this subgroup were more sensitive to immune checkpoint inhibitors.Conclusion Collectively,our findings demonstrate that pyroxia is involved in regulating the tumor immune microenvironment of UM.The PRGPI can effectively predict the prognosis of UM and the sensitivity of melanoma patients to immunotherapy,which provide guiding significance for the prognosis evaluation of UM patients and the selection of individualized immunotherapy.