Supplementary Material for: Rapidly and Slowly Growing Lineages in Chromosomal Instability-Type Gland-Forming Gastric Carcinomas as Revealed by Multisampling Analysis of DNA Copy-Number Profile

Background: To examine whether gastric carcinoma (GC) with chromosomal instability (CIN-type GC), the largest category in the Cancer Genome Atlas classification, consists of a single genetic lineage, we conducted a multisampling analysis of genomic DNA copy-number profile. Methods: We performed array-based comparative genomic hybridization using formalin-fixed paraffin-embedded tissues from 54 gland-forming GCs containing a total of 106 DNA samples from mucosal, extramucosal invasive, and lymph node lesions. Microarray data were analyzed by unsupervised hierarchical clustering and penetrance plots. Epstein-Barr virus infection status and mismatch repair (MMR) enzyme-silencing/p53/mucin expression were examined by in situ hybridization and immunohistochemistry, respectively. Results: The samples examined were divided into gain-rich cluster A and loss-rich cluster B, which were different in tumor locus and patient age. The T1/T2–4 ratio, the frequency of small cancers (diameter ≤2–4 cm), and intestinal mucin expression were higher in cluster B than in cluster A, but there were no significant differences in the frequencies of MMR silencing, mutant p53 pattern, and lymph node metastasis between the 2 clusters. Conclusions: We demonstrated that CIN-type GC could be categorized into 2 genetic lineages which are different in terms of rapidity of local extension but similar in terms of nodal metastasis risk.

背景：为探究染色体不稳定型胃癌（CIN-type GC）——癌症基因组图谱（Cancer Genome Atlas）分类中占比最高的胃癌亚型——是否仅由单一遗传谱系构成，我们针对基因组DNA拷贝数特征开展了多样本分析。
方法：我们对54例腺体型胃癌的福尔马林固定石蜡包埋组织开展基于阵列的比较基因组杂交分析，共获取来自黏膜病灶、黏膜外浸润病灶及淋巴结病灶的106份DNA样本。通过无监督层次聚类（unsupervised hierarchical clustering）与外显率图谱分析微阵列数据，并分别采用原位杂交（in situ hybridization）检测EB病毒（Epstein-Barr virus）感染状态，免疫组织化学（immunohistochemistry）检测错配修复（mismatch repair, MMR）基因沉默、p53及黏蛋白的表达情况。
结果：本次纳入分析的样本被划分为富集拷贝数扩增的A簇与富集拷贝数缺失的B簇，二者在肿瘤发病部位与患者年龄上存在显著差异。B簇的T1/T2-4分期占比、小癌灶（直径≤2~4 cm）发生率及肠型黏蛋白表达率均高于A簇；但两组在错配修复基因沉默发生率、突变型p53模式占比及淋巴结转移发生率上无统计学差异。
结论：本研究证实染色体不稳定型胃癌可划分为两类遗传谱系，二者在局部浸润速度上存在差异，但淋巴结转移风险并无显著不同。