Zheng Hang, Bai Yuge, Wang Jingui, Chen Shanwen, Zhang Junling, Zhu Jing, Liu Yucun, Wang Xin
Department of General Surgery, Peking University First Hospital, Beijing, China.
Front Mol Biosci. 2021 Apr 29;8:649363. doi: 10.3389/fmolb.2021.649363. eCollection 2021.
Immunotherapy has achieved efficacy for advanced colorectal cancer (CRC) patients with a mismatch-repair-deficient (dMMR) subtype. However, little immunotherapy efficacy was observed in patients with the mismatch repair-proficient (pMMR) subtype, and hence, identifying new immune therapeutic targets is imperative for those patients. In this study, transcriptome data of stage III/IV CRC patients were retrieved from the Gene Expression Omnibus database. The CIBERSORT algorithm was used to quantify immune cellular compositions, and the results revealed that M2 macrophage fractions were higher in pMMR patients as compared with those with the dMMR subtype; moreover, pMMR patients with higher M2 macrophage fractions experienced shorter overall survival (OS). Subsequently, weighted gene co-expression network analysis and protein-protein interaction network analysis identified six hub genes related to M2 macrophage infiltrations in pMMR CRC patients: , , , , , and . Univariate and multivariate Cox regression analyses then determined as the independent prognostic biomarker for OS. was upregulated specifically the in CMS4 CRC subtype, and single-sample Gene Set Enrichment Analysis (ssGSEA) revealed that was significantly correlated with angiogenesis and TGF-β signaling gene sets enrichment scores in stage III/IV pMMR CRC samples. The Estimation of STromal and Immune cells in MAlignant Tumor tissues using Expression data (ESTIMATE) algorithm and correlation analysis revealed that was significantly associated with multiple immune and stromal components in a tumor microenvironment. In addition, GSEA demonstrated that high expression of was significantly correlated with antigen processing and presentation, chemokine signaling, leukocyte transendothelial migration, vascular smooth muscle contraction, cytokine-cytokine receptor interaction, cell adhesion molecules, focal adhesion, MAPK, and TGF-beta signaling pathways. Furthermore, the proliferation, invasion, and migration abilities of cancer cells were suppressed after reducing expression in CRC cell lines. Taken together, multiple bioinformatics analyses and cell-level assays demonstrated that could serve as a prognostic biomarker and a prospective therapeutic target for stage III/IV pMMR CRCs.
免疫疗法已在错配修复缺陷（dMMR）亚型的晚期结直肠癌（CRC）患者中取得疗效。然而，在错配修复 proficient（pMMR）亚型的患者中观察到的免疫疗法疗效甚微，因此，为这些患者确定新的免疫治疗靶点势在必行。在本研究中，从基因表达综合数据库中检索了 III/IV 期 CRC 患者的转录组数据。使用 CIBERSORT 算法对免疫细胞组成进行定量，结果显示，与 dMMR 亚型患者相比，pMMR 患者中的 M2 巨噬细胞分数更高；此外，M2 巨噬细胞分数较高的 pMMR 患者总生存期（OS）较短。随后，加权基因共表达网络分析和蛋白质-蛋白质相互作用网络分析确定了六个与 pMMR CRC 患者中 M2 巨噬细胞浸润相关的枢纽基因： 、 、 、 、 、 和 。单变量和多变量 Cox 回归分析随后确定 为 OS 的独立预后生物标志物。 在 CMS4 CRC 亚型中特异性上调，单样本基因集富集分析（ssGSEA）显示， 在 III/IV 期 pMMR CRC 样本中与血管生成和 TGF-β 信号基因集富集分数显著相关。使用表达数据（ESTIMATE）算法对恶性肿瘤组织中的基质和免疫细胞进行估计并进行相关分析，结果显示， 与肿瘤微环境中的多种免疫和基质成分显著相关。此外，基因集富集分析（GSEA）表明， 的高表达与抗原加工和呈递、趋化因子信号传导、白细胞跨内皮迁移、血管平滑肌收缩、细胞因子-细胞因子受体相互作用、细胞粘附分子、粘着斑、MAPK 和 TGF-β 信号通路显著相关。此外，在 CRC 细胞系中降低 表达后，癌细胞的增殖、侵袭和迁移能力受到抑制。综上所述，多项生物信息学分析和细胞水平检测表明， 可作为 III/IV 期 pMMR CRC 的预后生物标志物和潜在治疗靶点。
