硒代磷酸合成酶2在皮肤黑素瘤中的表达及临床意义

Expression and clinical significance of SEPHS2 in cutaneous malignant melanoma

目的 利用生物信息学方法探讨硒代磷酸合成酶2(SEPHS2)在皮肤恶性黑素瘤(CMM)中的表达及临床意义。方法 下载TCGA和GTEx数据库中CMM和正常皮肤相关mRNA微阵列表达谱,比较CMM和正常皮肤的SEPHS2基因表达差异;下载GEO数据集GSE3189数据,比较SEPHS2在CMM和痣细胞之间的表达差异。同时利用HPA数据库信息分析其在CMM和正常皮肤黑素细胞中蛋白质水平的表达。利用K-M图,比较不同SEPHS2表达组CMM患者的生存差异,并利用Cox回归计算HR值;利用受试者工作特征曲线评价SEPHS2在CMM中的诊断效能。利用XENA.UCSC数据库分析CMM中SEPHS2基因甲基化情况,K-M图评价SEPHS2不同甲基化水平对预后的影响。利用GSVA包分析SEPHS2表达与CMM组织中免疫浸润相关免疫细胞的相关性。采用STRING数据库分析SEPHS2相关蛋白质-蛋白质相互作用网络信息,并利用GO、KEGG数据库和GSEA软件探讨SEPHS2在CMM中的功能及信号通路。结果 SEPHS2在CMM中的表达水平显著高于正常皮肤组织和痣细胞组织(P<0.001)。在CMM患者中,SEPHS2高表达组较低表达组总体生存率更低,显示SEPHS2具有良好的预后价值,并且SEPHS2对CMM具有良好的诊断价值(AUC=0.895,95%CI:0.876~0.913)。与SEPHS2基因高甲基化组相比,低甲基化组与CMM的不良预后相关,具有统计学意义(P=0.013)。在CMM中,SEPHS2表达与树突状细胞、自然杀伤细胞、T细胞、B细胞和细胞毒性细胞浸润呈负相关,与辅助性T细胞等免疫细胞浸润正相关,均具有统计学意义(P<0.05)。蛋白质-蛋白质相互作用分析显示SEPHS2与SEPSECS、SCLY、TXNRD1、TXNRD2和SELK等分子相互作用。GO、KEGG和GSEA通路富集分析显示SEPHS2及其相关基因参与了表皮形成、体液免疫、中性粒细胞活化与免疫应答、角蛋白丝及桥粒构成、IL-2、IL-2家族、IL-4-2、IL-10、IL-12-2和IL-12-STAT4、IL-17、IL-18、IL-27、B细胞受体、T细胞受体、PD-1及CTLA-4等多条免疫相关信号通路,并呈负相关。结论 SEPHS2在CMM组织中高表达,是CMM潜在的诊断和预后的标志物;SEPHS2不仅参与了硒蛋白的合成,而且还影响了肿瘤的免疫调节过程,可能成为CMM治疗靶点之一。

Objective To explore the expression and clinical significance of selenophosphoric synthetase 2(SEPHS2)in cutaneous malignant melanoma(CMM)by bioinformatics methods.Methods The mRNA microarray expression profiles related to CMM and normal skin were downloaded from TCGA and GTEx databases to compare the difference of SEPHS2 gene expression between CMM and normal skin.The GEO dataset GSE3189 was downloaded to compare the difference of SEPHS2 expression between CMM and nevus cells.At the same time,HPA database information was used to analyze its protein expression in CMM and normal melanocytes.The survival difference of CMM patients in different SEPHS2 expression groups was compared by K-M diagram,and HR value was calculated by Cox regression.Receiver operating characteristic curve w as used to evaluate the diagnostic efficacy of SEPHS2 in CMM.XENA.UCSC database was used to analyze the methylation of SEPHS2 gene in CMM,and K-M diagram was used to evaluate the impact of different methylation levels of SEPHS2 on prognosis.GSVA package was used to analyze the correlation between SEPHS2 expression and immune cells related to immune infiltration,and STRING database was used to analyze the protein-protein interaction network information related to SEPHS2.GO,KEGG databases and GSEA software were used to explore the function and signal pathway of SEPHS2 in CMM.Results The mRNA expression level of SEPHS2 in CMM was significantly higher than that in normal skin tissue and nevus cell tissue(P<0.001).The CMM patients with high expression of SEPHS2 were found to have a lower overall survival rate than those with low expression,suggesting that SEPHS2 is a promising prognostic marker,which had a good diagnostic value for CMM(AUC=0.895,95%CI:0.8760.913).Compared with SEPHS2 gene hypermethylation group,hypomethylation group was associated with poor prognosis of CMM,with statistical significance(P=0.013).The expression of SEPHS 2 in CMM was negatively correlated with the infiltration of dendritic cells,natural killer cells,T cells,B cells,and cytotoxic cells,and positively correlated with the infiltration of immune cells such as helper T cells,with statistical significance(P<0.05).Protein-protein interaction analysis showed that SEPHS2 interacted with SEPSEC,SCLY,TXNRD1,TXNRD2 and SELK.Enrichment analysis of GO,KEGG and GSEA pathways showed that SEPHS2 and its related genes were involved in and negatively correlated with epidermal formation,humoral immunity,neutrophil activation and immune response,keratin filament and desmosome composition,IL-2,IL-2 family,IL-4-2,IL-10,IL-12-2 and IL-12-STAT4,IL-17,IL-18,IL-27,B cell receptor,T cell receptor,PD-1,CTLA-4 and other immune-related signal pathways.Conclusion SEPHS2 is highly expressed in CMM tissues and is a potential marker for the diagnosis and prognosis of CMM.SEPHS2 is not only involved in the synthesis of selenoproteins,but also affects the immune regulation process of tumors,which may become one of the therapeutic targets of CMM.