中文摘要：

目的：研究食管鳞状细胞癌（ ESCC）的肿瘤内异质性。方法采用全基因组外显子测序和微阵列比较基因组拷贝数杂交的分析方法，对2例ESCC患者肿瘤内11个区域的全基因组基因突变及拷贝数变化进行检测，同时检测包括转移淋巴结基因组突变及拷贝数的变化。结果例1和例2患者4个肿瘤区域的单核苷酸多态性（SNPs）数目分别为（93±17）个和（124±28）个。这些SNPs主要为非同义突变、同义突变、无义突变、剪接位点突变。例1和例2患者的4个肿瘤区域缺失数分别为（40±6）个和（51±3）个。这些缺失主要发生于基因外显子（移码突变或非移码突变）、非翻译区及基因拼接区。所有肿瘤内各个区域均表现出明显的异质性，同一肿瘤不同区域基因突变谱仅有的相似性＜25％。肿瘤多个区域出现基因拷贝数增加或丢失，同一肿瘤不同区域基因拷贝数相似性＜20％。肿瘤进化分析表明，多个肿瘤细胞克隆共存于ESCC原发灶，转移性亚克隆可能来自于原发灶的肿瘤细胞克隆。 ESCC单区域取样不能反映肿瘤基因突变的全貌。结论 ESCC多区域的全基因组外显子测序研究可以为ESCC的肿瘤内异质性提供有力的证据。

英文摘要：

Objective To study the intratumor heterogeneity of esophageal squamous cell carcinoma （ ESCC） . Methods We used whole-exome sequencing and array-based comparative genomic hybridization to profile mutations and changes in copy number from 11 regions within 2 cases of ESCC and from the metastatic lymph nodes. Results The numbers of somatic single nuclear polymorphisms （ SNPs ） in 4 regions within the tumors in case 1 and case 2 were 93±17 and 124±28, respectively. The majority of SNPs were non synonymous mutations, synonymous mutations, nonsense mutations and splicing junction mutations. The average indels in the 4 tumor regions of case 1 and case 2 were 40 ± 6 and 51 ± 3, respectively. These small indels mainly occurred in exonic （ frame-shift and non？frame？shift ） , untranslational regions of genes and splicing junction regions. All regions from a tumor exhibitedo bvious heterogeneity, and mutational similarity of all four regions within a tumor was less than 25%. Furthermore, gene copy number alteration （ gain or loss） varied among multiple regions of a tumor, and the similarity of gene copy number was less than 20%. Phylogenetic analysis of the somatic mutation frequency suggests that multiple, genomic heterogeneous clones coexist within a primary ESCC, and metastatic subclones may evolve from the primarysp non-metastatic parental clone. These results indicated that a single-region sampling can not reflect the architecture of the genomic landscape of mutations in ESCC tumors. Conclusions Sequence analysis of whole genome exon in multiple regions can provide strong evidence for genomic heterogeneity in esophageal squamous cell carcinoma.