PO.CL09.04 · 临床研究
黑色素瘤患者标本中Ki67表达的转录组分析揭示不同的免疫特征
Transcriptomic profiling of Ki67 expression in melanoma patient specimens reveals distinct immune signatures
作者与单位 Authors & Affiliations
摘要 Abstract
中文摘要
背景：Ki67基因（MKI67）作为黑色素瘤及其他癌症亚型中高细胞活性的标志物具有临床相关性。我们假设，按MKI67高表达和MKI67低表达分层的人黑色素瘤组织转录组分析，可能与生物学活性的免疫特征以及临床结局相关。
方法：所分析的肿瘤组织包括皮下黑色素瘤转移部位和淋巴结（GSE22153，n=57）、肿瘤活检（GSE65904，n=214）、癌症基因组图谱（TCGA，n=443）、ICB治疗前活检（GSE78220，n=28），以及治疗前加治疗中的混合免疫检查点阻断（ICB）队列（GSE91061，n=65）。采用MKI67表达中位数对各组进行分层。使用xCell平台分析细胞亚群。采用分子特征数据库（MSigDB）内的Hallmark基因集进行基因集富集分析（GSEA）。采用Thorsson等人所述的免疫亚型分类。
结果：MKI67转录组表达与高增殖性基因集相关，包括E2F靶点、G2M检查点、有丝分裂纺锤体和MYC靶点v1/v2（所有通路|NES|>1.5且FDR<0.25）。在TCGA队列中，增殖和创伤愈合通路富集（p<0.05），进一步支持Ki67高确实指示更强细胞更替和活性这一概念。有趣的是，MKI67高组的沉默和非沉默突变率更高（分别为p=0.00187和0.00262），但新抗原并非如此（p=0.163）。卡方分析显示，TCGA数据集（n=441）中MKI67高表达（n=220）与KIT突变（n=13，p=0.043）以及CDKN2A突变（n=20，p=0.004）存在关联。xCell分析显示，在TCGA和GSE65904队列中MKI67高表达与Th1细胞浸润相关（p<0.05），但这种关联在Th2细胞中较弱。各组在种族、性别、解剖部位或黑色素瘤分期（如T、N）等临床特征方面与Ki-67表达的关系无统计学显著差异。总生存期（OS）和无病生存期（DFS）在100个月时间点均与较低的MKI67表达相关（分别为p=0.0004和p=0.0177），但在后续临床随访中这一差异消失。
结论：本研究利用MKI67转录组分析作为一种手段，探究黑色素瘤肿瘤与肿瘤免疫微环境及临床结局相关的潜在分子生物学。MKI67表达与独特的基因富集和免疫浸润以及组织突变的组合相关，值得进一步研究，作为临床决策的潜在工具。
查看英文原文 English abstract
Background: The Ki67 gene (MKI67) is clinically relevant as a marker of high cellular activity in melanoma among other cancer subtypes. We hypothesized that transcriptomic profiling of human melanoma tissue as stratified by MIK67-high and MKI67-low expression may correlate with immune signatures of biologic activity and with clinical outcomes.
Methods: Analyzed tumor tissue included subcutaneous melanoma metastatic sites and lymph nodes (GSE22153 n=57), tumor biopsies (GSE65904 n=214), The Cancer Genome Atlas (TCGA n=443), pre-ICB biopsies (GSE78220 n=28), and pre-treatment plus on-treatment mixed Immune Checkpoint Blockade (ICB) cohorts (GSE91061 n=65). Median MKI67 expression was utilized to stratify the groups. The xCell platform was utilized to analyze cellular subsets. Hallmark gene sets within the Molecular Signatures Database (MSigDB) were utilized for the Gene Set Enrichment Analysis (GSEA). The immune subtype classification as described by Thorsson et al. was utilized.
Results: The MKI67 transcriptomic expression correlated with highly proliferative genesets including E2F targets, G2M checkpoint, mitotic spindle, and MYC targets v1/v2 (|NES|>1.5 and FDR < 0.25 for all pathways). Within the TCGA cohort, the proliferative and wound healing pathways were enriched (p<0.05), further supporting the concept that Ki67-high is indeed indicative of greater cell turnover and activity. Interestingly, silent and non-silent mutation rates were higher in the MKI67-high group (p=0.00187 and 0.00262, respectively) but this was not the case for neoantigens (p=0.163). On Chi-squared analysis, the TCGA dataset (n=441) demonstrated an association between MKI67-high expression (n=220) and KIT mutations (n=13, p=0.043), as well as CDKN2A mutations (n=20, p=0.004). On xCell analysis, Th1 cells demonstrated MKI67-high expression was associated with Th1 cell infiltration in the TCGA and GSE65904 cohorts (p<0.05), but this associated was weaker for Th2 cells. There were no statistically significant differences across the groups in terms of clinical features such as race, gender, anatomic site or melanoma stage (e.g. T, N) as relating to Ki-67 expression. Overall Survival (OS) and Disease-Free Survival (DFS) were both associated with lower MKI67 expression at the 100-month time point (p=0.0004 and p=0.0177, respectively), but this difference was lost on later clinical follow-up.
Conclusions: We have herein utilized analysis of the MKI67 transcriptome as a means to interrogate the underlying molecular biology of melanoma tumors as they relate to the tumor immune microenvironment and clinical outcomes. MKI67 expression correlates with a unique constellation of gene enrichment and immune infiltration as well as tissue mutations and warrants further investigation as a potential tool for clinical decision-making.
利益披露 Disclosure
E. A. Fallon, None.