Table1_Identification and validation of SERPINE1 as a prognostic and immunological biomarker in pan-cancer and in ccRCC.xlsx

Background:SERPINE1, a serine protease inhibitor involved in the regulation of the plasminogen activation system, was recently identified as a cancer-related gene. However, its clinical significance and potential mechanisms in pan-cancer remain obscure.
Methods: In pan-cancer multi-omics data from public datasets, including The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx), and online web tools were used to analyze the expression of SERPINE1 in different cancers and its correlation with prognosis, genetic alteration, DNA promoter methylation, biological processes, immunoregulator expression levels, immune cell infiltration into tumor, tumor mutation burden (TMB), microsatellite instability (MSI), immunotherapy response and drug sensitivity. Further, two single-cell databases, Tumor Immune Single-cell Hub 2 (TISCH2) and CancerSEA, were used to explore the expression and potential roles of SERPINE1 at a single-cell level. The aberrant expression of SERPINE1 was further verified in clear cell renal cell carcinoma (ccRCC) through qRT-PCR of clinical patient samples, validation in independent cohorts using The Gene Expression Omnibus (GEO) database, and proteomic validation using the Clinical Proteomic Tumor Analysis Consortium (CPTAC) database.
Results: The expression of SERPINE1 was dysregulated in cancers and enriched in endothelial cells and fibroblasts. Copy number amplification and low DNA promoter methylation could be partly responsible for high SERPINE1 expression. High SERPINE1 expression was associated with poor prognosis in 21 cancers. The results of gene set enrichment analysis (GSEA) indicated SERPINE1 involvement in the immune response and tumor malignancy. SERPINE1 expression was also associated with the expression of several immunoregulators and immune cell infiltration and could play an immunosuppression role. Besides, SERPINE1 was found to be related with TMB, MSI, immunotherapy response and sensitivity to several drugs in cancers. Finally, the high expression of SERPINE1 in ccRCC was verified using qRT-PCR performed on patient samples, six independent GEO cohorts, and proteomic data from the CPTAC database.
Conclusion: The findings of the present study revealed that SERPINE1 exhibits aberrant expression in various types of cancers and is associated with cancer immunity and tumor malignancy, providing novel insights for individualized cancer treatment.

研究背景：SERPINE1是一种参与纤溶酶原激活系统调控的丝氨酸蛋白酶抑制剂，近期被鉴定为癌症相关基因，但其在泛癌中的临床意义与潜在机制仍不明确。
研究方法：本研究依托公共数据集的泛癌多组学数据，包括癌症基因组图谱（The Cancer Genome Atlas, TCGA）与基因型-组织表达（Genotype-Tissue Expression, GTEx），并结合在线网络工具，分析SERPINE1在不同癌症中的表达情况，及其与预后、基因变异、DNA启动子甲基化、生物学过程、免疫调节因子表达水平、肿瘤免疫细胞浸润、肿瘤突变负荷（Tumor Mutation Burden, TMB）、微卫星不稳定性（Microsatellite Instability, MSI）、免疫治疗响应及药物敏感性的相关性。此外，本研究使用肿瘤免疫单细胞枢纽2（Tumor Immune Single-cell Hub 2, TISCH2）与CancerSEA两个单细胞数据库，探索SERPINE1在单细胞水平的表达特征与潜在功能。进一步地，本研究通过临床患者样本的qRT-PCR验证透明细胞肾细胞癌（clear cell renal cell carcinoma, ccRCC）中SERPINE1的异常表达，采用基因表达综合（Gene Expression Omnibus, GEO）数据库的独立队列进行验证，并通过临床蛋白质组肿瘤分析联盟（Clinical Proteomic Tumor Analysis Consortium, CPTAC）数据库开展蛋白质组学验证。
研究结果：SERPINE1的表达在多种癌症中存在失调现象，且在内皮细胞与成纤维细胞中富集。拷贝数扩增与低水平DNA启动子甲基化可能是导致SERPINE1高表达的部分原因。SERPINE1高表达与21种癌症的不良预后显著相关。基因集富集分析（Gene Set Enrichment Analysis, GSEA）结果显示，SERPINE1参与免疫应答与肿瘤恶性进程。SERPINE1的表达还与多种免疫调节因子的表达及免疫细胞浸润水平相关，可能发挥免疫抑制作用。此外，SERPINE1还与癌症中的TMB、MSI、免疫治疗响应以及多种药物的敏感性存在关联。最后，本研究通过患者样本的qRT-PCR、6个独立GEO队列及CPTAC数据库的蛋白质组数据，验证了ccRCC中SERPINE1的高表达。
研究结论：本研究的发现揭示了SERPINE1在多种癌症中存在异常表达，且与癌症免疫及肿瘤恶性进程密切相关，为癌症个体化治疗提供了全新的研究视角。