EGFR variant heterogeneity in glioblastoma resolved through single-nucleus sequencing.
EGFR variant heterogeneity in glioblastoma resolved through single-nucleus sequencing.
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DOI：
10.1158/2159-8290.cd-13-0879
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发表时间：
2014-08
期刊：
影响因子：
28.2
通讯作者：
Ligon KL
中科院分区：
文献类型：
--
作者：
Francis JM;Zhang CZ;Maire CL;Jung J;Manzo VE;Adalsteinsson VA;Homer H;Haidar S;Blumenstiel B;Pedamallu CS;Ligon AH;Love JC;Meyerson M;Ligon KL
EGFR 扩增的胶质母细胞瘤约占新诊断病例的 50%，最近的研究表明同一肿瘤内多种 EGFR 畸变频繁共存，这对突变协同和治疗耐药产生影响。然而，大量肿瘤测序研究无法解析单个肿瘤细胞内多个 EGFR 畸变如何与其他突变共存的模式。在这里，我们应用基于群体的单细胞全基因组测序方法来表征 EGFR 扩增的胶质母细胞瘤的基因组异质性。我们的分析有效地识别了克隆事件，包括超级增强子向 TERT 启动子的新易位，以及肿瘤内的亚克隆杂合性丢失和多个 EGFR 突变变体。将 EGFR 突变与细胞层次相关联表明，在大块肿瘤中鉴定出的 EGFR 截短变体（EGFRvII 和 EGFR 羧基末端缺失）分离成不重叠的亚克隆群体。体外和体内功能研究表明，EGFRvII 具有致癌性，并且对目前正在进行临床试验的 EGFR 抑制剂敏感。因此，单个肿瘤内 EGFR 的多种激活突变与其他亚克隆突变之间的关联支持了增殖和克隆多样化的内在机制，对治疗耐药具有广泛的影响。
Glioblastomas with EGFR amplification represent approximately 50% of newly diagnosed cases and recent studies have revealed frequent coexistence of multiple EGFR aberrations within the same tumor with implications for mutation cooperation and treatment resistance. However, bulk tumor sequencing studies cannot resolve the patterns of how the multiple EGFR aberrations coexist with other mutations within single tumor cells. Here we applied a population-based single-cell whole genome sequencing methodology to characterize genomic heterogeneity in EGFR amplified glioblastomas. Our analysis effectively identified clonal events, including a novel translocation of a super enhancer to the TERT promoter, as well as subclonal loss-of-heterozygosity and multiple EGFR mutational variants within tumors. Correlating the EGFR mutations onto the cellular hierarchy revealed that EGFR truncation variants (EGFRvII and EGFR Carboxyl-terminal deletions) identified in the bulk tumor segregate into non-overlapping subclonal populations. In vitro and in vivo functional studies show EGFRvII is oncogenic and sensitive to EGFR inhibitors currently in clinical trials. Thus the association between diverse activating mutations in EGFR and other subclonal mutations within a single tumor supports an intrinsic mechanism for proliferative and clonal diversification with broad implications in resistance to treatment.