Multi-regional sequencing reveals clonal and polyclonal seeding from primary tumor to metastases in advanced gastric cancer
- 作者列表："Hirotsu, Yosuke","Hada, Masao","Amemiya, Kenji","Oyama, Toshio","Mochizuki, Hitoshi","Omata, Masao
Background Tumor metastases to lymph nodes and distant organs are associated with worse prognosis in gastric cancer. However, little is known about the genetic profiles, subclonal architecture, and evolutional processes across primary tumors and metastases. Methods We analyzed the genetic alterations of 106 multiregional samples including primary tumors, lymph node metastases, and visceral metastases from 10 patients with advanced gastric cancer. Histologically different portions were obtained by laser-capture microdissection. We reconstructed the subclonal architectures and inferred the primary to lymph or visceral metastatic seeding patterns. Results The different histological portions in primary tumors had common mutations, suggesting common ancestral tumor origins transformed into distinct histological types. In almost all cases, TP53 mutations were identified as clonal mutations across primary tumors and metastases. Subclonal reconstruction and phylogenetic analysis showed primary tumors were classified into monoclonal or polyclonal tumors. All monoclonal primary tumors disseminated as metastases with the same tumor composition (100%, 26/26 samples). In contrast, polyclonal primary tumors mainly spread as metastases by way of polyclonal seeding (84%: 37/44 samples). Conclusions Clonal mutations were maintained at both the primary and metastatic sites and genetic divergence of these was low. These findings shed light on the genetic basis of primary tumor dissemination and metastatic processes in advanced gastric cancer.
背景: 胃癌淋巴结和远处器官的肿瘤转移与较差的预后相关。然而，关于原发肿瘤和转移灶的遗传谱、亚克隆结构和进化过程知之甚少。方法我们分析了 10 例晚期胃癌患者 106 例多区域样本的遗传学改变，包括原发肿瘤、淋巴结转移和内脏转移。通过激光捕获显微切割获得组织学不同的部分。我们重建了亚克隆架构，并推断了原发至淋巴或内脏转移的种植模式。结果原发肿瘤不同组织学部位有共同的突变，提示共同的祖先肿瘤起源转化为不同的组织学类型。在几乎所有的病例中，TP53 突变被鉴定为跨原发肿瘤和转移灶的克隆性突变。亚克隆重建和系统发育分析显示原发肿瘤分为单克隆或多克隆肿瘤。所有单克隆原发肿瘤均播散为转移灶，肿瘤成分相同 (100%，26/26 例样本)。相比之下，多克隆原发肿瘤主要通过多克隆种植 (84%: 37/44 个样本) 以转移方式扩散。结论克隆性突变在原发和转移部位均保持不变，且遗传差异较低。这些发现揭示了晚期胃癌原发肿瘤播散和转移过程的遗传基础。
METHODS::Diffuse gastric cancer (DGC) is a lethal malignancy lacking effective systemic therapy. Among the most provocative recent results in DGC has been that the alter of the cellular cytoskeleton and intercellular adhesion. CD2-associated protein (CD2AP) is one of the critical proteins regulating cytoskeleton assembly and intercellular adhesion. However, no study has investigated the expression and biological significance of CD2AP in gastric cancer (GC) to date. Therefore, the aim of our study was to explore if the expression of CD2AP is associated with any clinical features of GC and to elucidate the underlying mechanism. Immunohistochemistry of 620 patient tissue samples indicated that the expression of CD2AP is downregulated in DGC. Moreover, a low CD2AP level was indicative of poor patient prognosis. In vitro, forced expression of CD2AP caused a significant decrease in the migration and invasion of GC cells, whereas depletion of CD2AP had the opposite effect. Immunofluorescence analysis indicated that CD2AP promoted cellular adhesion and influenced cell cytoskeleton assembly via interaction with the F-actin capping protein CAPZA1. Overall, the upregulation of CD2AP could attenuate GC metastasis, suggesting CD2AP as a novel biomarker for the prognosis and treatment of patients with GC.
METHODS::Aim: To identify the methylated-differentially expressed genes (MDEGs) that may serve as diagnostic markers and therapeutic targets in Epstein-Barr virus-associated gastric cancer (EBVaGC) and to explore the methylation-based pathways for elucidating biological mechanisms of EBVaGC. Materials & methods: Gene expression and methylation profiles were downloaded from GEO database. MDEGs were identified by GEO2R. Pathway enrichment analyses were conducted based on DAVID database. Hub genes were identified by Cytoscape, which were further verified by The Cancer Genome Atlas database. Results: A total of 367 hypermethylated, lowly expressed genes were enriched in specific patterns of cell differentiation. 31 hypomethylated, highly expressed genes demonstrated enrichment in regulation of immune system process. After validation using The Cancer Genome Atlas database, seven genes were confirmed to be significantly different hub genes in EBVaGC. Conclusion: EBVaGC-specific MDEGs and pathways can be served as potential biomarkers for precise diagnosis and treatment of EBVaGC and provide novel insights into the mechanisms involved.
METHODS:Gastric adenocarcinoma, like other cancers, is a multifactorial genetic disease, andmetastasis of cancer cells is one of the main features of this illness. The expressionlevels of the CFL1 gene have been modulated in this pathway. Using small interferingRNA (siRNA) in the treatment of gastric cancer is considered a hopeful genetherapeutic approach. The present study reported the level of CFL1 genes betweentumor and margin and healthy tissue of gastric cancer. Also, the features of a cationicnanoparticle with a polymer coating containing polyacrylic acid and polyethylenei-mine that were used in the delivery of CFL1 siRNA, were shown. Then thecytotoxicity, cellular uptake, and gene silencing efficiency of this nanoparticle wereevaluated with CFL1siRNA. Method:In this study, the CFL1 gene expression was measured in 40 gastricadenocarcinoma, marginal and 15 healthy biopsy samples by a real‐time polymerasechain reaction. Physicochemical characteristics, apoptosis, and inhibition of migrationof the delivery of CFL1 siRNA by nanoparticle and lipofectamine were investigated ingastric cancer cells. Result:The CFL1 expression was remarkably increased in gastric cancer tissues incomparison with the marginal samples and normal tissues (p< .05) and the biomarkerindex for CFL1 was obtained as 0.94, then this gene can be probably used as abiomarker for gastric cancer. After treatment of the AGS cell line by CFL1 siRNA, theCFL1 expression level of mRNA and migration in AGS cells were remarkablysuppressed after transfection. Furthermore, the amount of apoptosis increased(p< .05). Conclusion:Our results demonstrated that CFL1 downregulation in AGS cells caninterdict cell migration. Finally, our outcomes propose that CFL1 can function as anoncogenic gene in gastric cancer and would be considered as a potential purpose ofgene therapy for gastric cancer treatment