衰老与癌症预后显著相关。本研究旨在构建结直肠癌（CRC）衰老相关的预后模型，并研究衰老对肿瘤微环境的影响。从The Cancer Genome Atlas（TCGA）和Gene Expression Omnibus（GEO）数据库下载了CRC病例的转录组和临床数据。通过单变量Cox回归检测出的衰老相关预后基因包括在最小绝对收缩和选择算子（LASSO）分析中以构建模型。采用受试者工作特征曲线（ROC）和生存分析验证了该模型的有效性。鉴定差异表达基因（DEGs），并进行基因本体论（GO）和Kyoto Encyclopedia of Genes and Genomes（KEGG）通路富集。使用CIBERSORT和Immuno-Oncology Biological Research（IOBR）研究肿瘤微环境的特征。使用单细胞RNA-seq数据研究模型基因在各种细胞类型中的表达水平。利用人类结肠组织进行p21、SPP1和CD68的免疫荧光染色。最终构建了一个由七个基因（PTGER2、FGF2、IGFBP3、ANGPTL4、DKK1、WNT16和SPP1）组成的模型。使用中位数得分作为阈值将患者分为高危和低危。1、2和3年疾病特异性生存（DSS）的ROC曲线下面积（AUC）分别为0.731、0.651和0.643。生存分析显示，建模和验证队列中低风险患者的5年DSS更好。 GO和KEGG分析显示，DEGs富集在细胞外基质-受体相互作用、聚焦粘附和蛋白消化和吸收中。 CIBERSORT和IOBR分析显示，高危亚组中巨噬细胞丰富，免疫抑制环境。低风险患者对免疫治疗的反应率高于高风险患者。 ScRNA-seq数据表明，在具有强的衰老相关分泌表型（SASP）特征的一部分巨噬细胞中，SPP1的表达高。在CRC肿瘤组织中，我们发现高级别肿瘤中SPP1+巨噬细胞被大量衰老的肿瘤细胞所包围。我们的研究提出了一个基于衰老相关基因的新型模型，可以识别具有不良预后和免疫抑制性肿瘤微环境的CRC患者。SPP1+巨噬细胞可能与导致不良预后的细胞衰老相关。版权所有©2023 Yu, Chen, Xu, Mao和Sun。

Senescence is significantly associated with cancer prognosis. This study aimed to construct a senescence-related prognostic model for colorectal cancer (CRC) and to investigate the influence of senescence on the tumor microenvironment.Transcriptome and clinical data of CRC cases were downloaded from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. Senescence-related prognostic genes detected by univariate Cox regression were included in Least Absolute Shrinkage and Selection Operator (LASSO) analysis to construct a model. The efficacy of the model was validated using the receiver operating characteristic (ROC) curve and survival analysis. Differentially expressed genes (DEGs) were identified and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment were performed. CIBERSORT and Immuno-Oncology Biological Research (IOBR) were used to investigate the features of the tumor microenvironment. Single-cell RNA-seq data were used to investigate the expression levels of model genes in various cell types. Immunofluorescence staining for p21, SPP1, and CD68 was performed with human colon tissues.A seven-gene (PTGER2, FGF2, IGFBP3, ANGPTL4, DKK1, WNT16 and SPP1) model was finally constructed. Patients were classified as high- or low-risk using the median score as the threshold. The area under the ROC curve (AUC) for the 1-, 2-, and 3-year disease-specific survival (DSS) were 0.731, 0.651, and 0.643, respectively. Survival analysis showed a better 5-year DSS in low-risk patients in the construction and validation cohorts. GO and KEGG analyses revealed that DEGs were enriched in extracellular matrix (ECM)-receptor interactions, focal adhesion, and protein digestion and absorption. CIBERSORT and IOBR analyses revealed an abundance of macrophages and an immunosuppressive environment in the high-risk subgroup. Low-risk patients had higher response rates to immunotherapy than high-risk patients. ScRNA-seq data revealed high expression of SPP1 in a subset of macrophages with strong senescence-associated secretory phenotype (SASP) features. Using CRC tumor tissues, we discovered that SPP1+ macrophages were surrounded by a large number of senescent tumor cells in high-grade tumors.Our study presents a novel model based on senescence-related genes that can identify CRC patients with a poor prognosis and an immunosuppressive tumor microenvironment. SPP1+ macrophages may correlate with cell senescence leading to poor prognosis.Copyright © 2023 Yu, Chen, Xu, Mao and Sun.