The Role And Potential Mechanism Of PRRX1 In The Progression Of Uveal Melanoma

Objective:To find a novel prognostic marker related to the tumor microenvironment(TME)of uveal melanoma(UM),and to further explore its role and possible mechanism in the occurrence,development,invasion and metastasis of UM.Methods:1.Based on the clinical characteristics and gene expression data of 80samples from The Cancer Genome Atlas(TCGA)database,the"ESTIMATE"algorithm and LASSO-Cox regression model were used to identify TME-and prognosis-related hub genes.2.PRRX1 was selected for constructing a prognostic model and validated using the Gene Expression Omnibus(GEO)dataset(n=63).The predictive performance of PRRX1 as a prognostic marker for UM was assessed using Cox proportional hazards models,receiver operating characteristic(ROC)curves,pan-cancer and chromosomal abnormality correlation analysis.3.After quantifying the TME components using Microenvironment Cell Populations-counter(MCP-counter),the PRRX1-related immunological characteristics were further analyzed.Gene set enrichment analysis(GSEA)was used to investigate the underlying mechanisms by which PRRX1 regulates UM progression.4.The PRRX1 gene in human invasive choroidal melanoma cells Mu M-2B was silenced with specific small interfering RNA(siRNA),and the interference efficiency was verified by Western blot.5.The effect of PRRX1 down-regulation on the invasion,migration of Mu M-2B cells was investigated by Transwell invasion assay and scratch assay.the effect of down-regulation of PRRX1 on epithelial-mesenchymal transition(EMT)markers in Mu M-2B cells was examined by Western blot.Results:1.The immune and stromal components in the TME of UM patients were associated with poor prognosis,patients with higher immune scores and stromal scores had shorter overall survival(OS).2.Higher PRRX1 expression was associated with poorer OS and metastasis-free survival(MFS)in UM patients.PRRX1 was an independent and effective factor affecting the prognosis of UM patients.3.PRRX1 was positively correlated with the expression of immune checkpoint genes(CTLA4,PDCD1,TIGIT,LAG3,CD274),negatively correlated with tumor mutation burden(TMB),and positively correlated with 8 tumor microenvironment cells(CD8~+T cells,cytotoxic lymphocytes,NK cells,cells of the monocytic lineage,myeloid dendritic cells,neutrophils,endothelial cells,and fibroblasts).GSEA demonstrated that angiogenesis,EMT,inflammation,and immune-related signaling pathways were significantly enriched in UM samples with high PRRX1expression.4.Transwell invasion assay,scratch assay demonstrated that down-regulation of PRRX1 could attenuate the invasion and migration of human invasive choroidal melanoma cells Mu M-2B;Western blot results showed that after down-regulation of PRRX1,the expression of epithelial marker E-Cadherin was significantly increased,the expression of mesenchymal marker N-Cadherin and EMT transcription factor Snail were significantly decreased.Conclusion:1.PRRX1 is an independent and effective TME-related adverse prognostic factor in UM.2.Down-regulation of PRRX1 can inhibit the invasion and migration of UM cells,attenuate the EMT process and affect the tumor progress,PRRX1 is a potential therapeutic target for UM.