背景：结肠腺癌(COAD)是一种异质性肿瘤，衰老在癌症发生中至关重要。本研究旨在确定基于衰老的亚型并构建一种预后标记来预测COAD患者的预后并指导免疫治疗或化疗决策。 方法：根据来自Gene Expression Omnibus (GEO)数据库中13个样本的单细胞RNA测序（scRNA-seq）数据，我们评估了细胞衰老特征。从癌症基因组图谱(TCGA)数据库中获取转录组数据、拷贝数变异(CNV)和单核苷酸变异(SNV)数据。GSE39582和GSE17537用于验证。使用无监督一致性聚类分析识别衰老亚型，并使用单变量Cox分析和最小绝对缩减选择算子（LASSO）开发预测标记。使用半数抑制浓度（IC50）值预测风险组对化疗的响应。我们进一步分析了风险基因表达与甲基化水平的关系。预测性能由诊断图评估。 结果：衰老相关通路在恶性细胞和bulkrna-seq中高度富集，并验证了细胞衰老。我们确定了三种衰老亚型，其中clust3中的患者预后最差，T分期较高，伴随着更高的肿瘤突变负荷和突变、激活的炎症反应、更高的免疫细胞浸润和更高的免疫逃逸倾向。使用11个基因（MFNG，GPRC5B，TNNT1，CCL22，NOXA1，PABPC1L，PCOLCE2，MID2，CPA3，HSPA1A和CALB1）建立了一种基于衰老的标记，并准确预测高风险患者的低预后。外部队列验证了其稳健性。低风险患者对小分子药物，包括厄洛替尼、舒尼替尼、MG-132、CGP-082996、AZ628、索拉非尼、VX-680和Z-LLNle-CHO更敏感。风险评分是独立的预后因素，诊断图确认了其可靠性。四个风险基因(CALB1、CPA3、NOXA1和TNNT1)与其甲基化水平呈显著正相关，而有六个基因(CCL22、GPRC5B、HSPA1A、MFNG、PABPC1L和PCOLCE2)与其甲基化水平呈负相关。 结论：本研究从衰老的角度提供了COAD的异质性的新认识，并为COAD的预后预测开发了标记。版权所有 © 2023 Feng, Fu and Nie。

Background: Colon adenocarcinoma (COAD) is a heterogeneous tumor and senescence is crucial in the occurrence of cancer. This study aimed to identify senescence-based subtypes and construct a prognostic signature to predict the prognosis and guide immunotherapy or chemotherapy decisions for COAD patients. Methods: Based on the single-cell RNA sequencing (scRNA-seq) data of 13 samples from the Gene Expression Omnibus (GEO) database, we assessed cellular senescence characteristics. Transcriptome data, copy number variations (CNVs) and single nucleotide variations (SNVs) data were obtained from The Cancer Genome Atlas (TCGA) database. GSE39582 and GSE17537 were used for validation. Senescence subtypes were identified using unsupervised consensus clustering analysis, and a prognostic signature was developed using univariate Cox analysis and least absolute shrinkage and selection operator (LASSO). Response of risk groups to chemotherapy was predicted using the half-maximal inhibitory concentration (IC50) values. We further analyzed the relationship between risk gene expression and methylation level. The prediction performance was assessed by nomogram. Results: Senescence-related pathways were highly enriched in malignant cells and bulk RNA-seq verified cellular senescence. Three senescence subtypes were identified, in which patients in clust3 had poorest prognosis and higher T stage, accompanied with higher tumor mutation burden (TMB) and mutations, activated inflammatory response, more immune cell infiltration, and higher immune escape tendency. A senescence-based signature using 11 genes (MFNG, GPRC5B, TNNT1, CCL22, NOXA1, PABPC1L, PCOLCE2, MID2, CPA3, HSPA1A, and CALB1) was established, and accurately predicted a lower prognosis in high risk patients. Its robustness was validated by external cohort. Low risk patients were more sensitive to small molecule drugs including Erlotinib, Sunitinib, MG-132, CGP-082996, AZ628, Sorafenib, VX-680, and Z-LLNle-CHO. Risk score was an independent prognostic factor and nomogram confirmed its reliability. Four risk genes (CALB1, CPA3, NOXA1, and TNNT1) had significant positive correlation with their methylation level, while six genes (CCL22, GPRC5B, HSPA1A, MFNG, PABPC1L, and PCOLCE2) were negatively correlated with their methylation level. Conclusion: This study provides novel understanding of heterogeneity in COAD from the perspective of senescence, and develops signatures for prognosis prediction in COAD.Copyright © 2023 Feng, Fu and Nie.