Department of Epidemiology and Biostatistics, Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Medicine, School of Public Health, Nanjing Medical University, Nanjing, China; State Key Laboratory of Reproductive Medicine, International Joint Research Center for Environment and Human Health, Nanjing Medical University, Nanjing, China.
Department of Epidemiology and Biostatistics, Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Medicine, School of Public Health, Nanjing Medical University, Nanjing, China.
Gastroenterology. 2017 Jun;152(8):2011-2021. doi: 10.1053/j.gastro.2017.02.017. Epub 2017 Feb 27.
BACKGROUND & AIMS: Several genetic variants have been associated with gastric cancer risk, although these account for only a fraction of cases of gastric cancer. We aimed to identify low-frequency and other genetic variants that determine gastric cancer susceptibility.
We performed exome array analysis of DNA in blood samples from 1113 patients with gastric cancer, collected at hospitals from 2006 to 2010 in China, and 1848 individuals without cancer (controls) undergoing physical examinations. Among 71,290 variants analyzed (including 25,784 common variants), 24 variants were selected and replicated in an analysis of DNA in blood samples from 4687 additional cases of gastric cancer and 5780 controls. We compared expression of candidate genes in tumor vs normal gastric tissues using data from TCGA and performed functional annotation analyses. An immortalized human gastric epithelial cell line (GES1) and 7 human gastric cancer lines were used to express transgenes, knock down gene expression (with small interfering RNAs), disrupt genes (using the CRISPR/Cas9 system), or assess expression of reporter constructs. We measured cell proliferation, colony formation, invasion, and migration, and assessed growth of xenograft tumors in nude mice.
A low-frequency missense variant rs112754928 in the SPOC domain containing 1 gene (SPOCD1; encoding p.Arg71Trp), at 1p35.2, was reproducibly associated with reduced risk of gastric cancer (odds ratio, 0.56; P = 3.48 × 10). SPOCD1 was overexpressed in gastric tumors, and knockout of SPOCD1 reduced gastric cancer cell proliferation, invasive activity, and migration, as well as growth of xenograft tumors in nude mice. We also associated the variant rs1679709 at 6p22.1 with reduced risk for gastric cancer (odds ratio, 0.80; P = 1.17 × 10). The protective allele rs1679709-A correlated with the surrounding haplotype rs2799077-T-rs2799079-C, which reduced the enhancer activity of this site to decrease expression of the butyrophilin subfamily 3 member A2 gene (BTN3A2). BTN3A2 is overexpressed in gastric tumors, and deletion of BTN3A2 inhibited proliferation, migration, and invasion of gastric cancer cells.
We have associated variants at 1p35.2 and 6p22.1 with gastric cancer risk, indicating a role for SPOCD1 and BTN3A2 in gastric carcinogenesis.
已有多种遗传变异与胃癌风险相关，但这些仅能解释胃癌病例的一小部分。我们旨在鉴定决定胃癌易感性的低频和其他遗传变异。
我们对 2006 年至 2010 年间在中国医院就诊的 1113 例胃癌患者和 1848 例接受体检的无癌症个体（对照）的血液样本进行外显子组分析。在分析的 71290 个变体（包括 25784 个常见变体）中，选择了 24 个变体，并在对另外 4687 例胃癌病例和 5780 例对照的血液样本进行分析中进行了复制。我们使用 TCGA 的数据比较了候选基因在肿瘤与正常胃组织中的表达，并进行了功能注释分析。我们使用转染、小干扰 RNA 敲低基因表达、CRISPR/Cas9 系统敲除基因或评估报告基因构建体的表达来检测永生化人胃上皮细胞系（GES1）和 7 个人胃癌系中的候选基因。我们测量了细胞增殖、集落形成、侵袭和迁移，并评估了裸鼠异种移植肿瘤的生长。
在 1p35.2 处 SPOC 结构域包含 1 基因（编码 p.Arg71Trp 的 SPOCD1）中的低频错义变异 rs112754928 与胃癌风险降低呈可重复相关（比值比，0.56；P=3.48×10）。SPOCD1 在胃肿瘤中过表达，SPOCD1 敲除降低了胃癌细胞的增殖、侵袭活性和迁移，以及裸鼠异种移植肿瘤的生长。我们还将位于 6p22.1 的变体 rs1679709 与胃癌风险降低相关联（比值比，0.80；P=1.17×10）。保护性等位基因 rs1679709-A 与周围的单倍型 rs2799077-T-rs2799079-C 相关，该单倍型降低了该位点的增强子活性，从而降低了丁酰胆碱结合蛋白亚家族 3 成员 A2 基因（BTN3A2）的表达。BTN3A2 在胃肿瘤中过表达，BTN3A2 的缺失抑制了胃癌细胞的增殖、迁移和侵袭。
我们将位于 1p35.2 和 6p22.1 的变异与胃癌风险相关联，表明 SPOCD1 和 BTN3A2 在胃癌发生中起作用。
