胃癌在2012 世界衛生組織的統計中發生率為第五名，其中以胃腺癌為主。在2014
年美國癌症基因體圖譜計畫(TCGA)中針對胃癌進行多種分子鑑定將胃癌區分成四種
子型(人類泡疹病毒第四型關連、微衛星不穩定、染色體不穩定以及基因體穩定)。
在本研究中，我們與長庚醫院合作，針對19 個胃癌(包括6 個腸道型胃癌、7 個瀰
漫型胃癌、6 個混合型)檢體進行409 個癌症相關基因次世代定序。與TCGA 的結果
相同的發現在RTK/RAS/PI(3)K、TGF-β、β-catenin 訊息傳遞路徑以及細胞週期有高度的基因變異，其中調控細胞增生和爬行的RTK/RAS/PI(3)K 訊息傳遞路徑變異最大。在第二批76 個胃癌檢體(包括35 個腸道型胃癌、28 個瀰漫型胃癌、12 個混合型、1 個未知)中鎖定Kras 做進一步的次世代定序分析。整合95 個胃癌檢體中，共發現四個基因變異，包括G12A (1.05%)、G12D (1.05%)以及G13D (2.11%)。在與臨床病理資料分析發現Kras 基因變異較常出現於賁門區域(p = 0.022)，且較常為腸道型胃癌。在細胞實驗中，我們發現Kras G12A、G12V 和G13D 基因變異會導致細胞型態呈現紡錘狀且增強其爬行能力。總結，本篇研究發現台灣胃癌病患有4.04% Kras基因變異，屬於少數，其中變異位置皆位於 P-loop 上，此類腫瘤較常出現於賁門附近，在細胞實驗中發現這些變異會增家癌細胞的爬行能力。

Gastric cancer (GC) is the fifth most common cancer in 2012 and most of the case is adenocarcinomas. The Cancer Genome Atlas (TCGA) project of GCs has defined four subtypes of mutational signatures (Epstein–Barr virus-associated, microsatellite instability, chromosomal instability, and genomically stable signatures).We first performed ultra-deep targeted sequencing analysis of 19 gastric tumors (intestinal, n = 6; diffuse, n = 7; mixed, n = 6) to screen for mutations in 409 cancer-related genes in collaboration with CGMH. TCGA and our data revealed that the high alteration on three pathways, RTK/RAS/PI(3)K, TGF-β, β-catenin pathway and cell cycle. RTK/RAS/PI(3)K which controls cell
proliferation and migration had the highest alterations. We further characterized Kras mutation for 76 GC cases (intestinal, n = 35; diffuse, n = 28; mixed, n = 12; unclassified, n = 1). Of 95, mutation was detected in four cases (4.21%): G12A (1.05%), G12D (1.05%), and G13D (2.11%). Analysis of clinicopathological parameters revealed that Kras mutation gastric cancer appeared in cardia gastric more with p = 0.022. Intestinal type GC has higher
Kras mutation rate than diffuse type. Functional characterization of Kras mutations G12A, G12V and G13D in MKN28 revealed a higher level of migratory activity and a spindle-like phenotype than wild type. Together, this study reports a small proportion (4.21% = 4
of 95) of GC patients who carry specific Kras P-loop mutations associated with cardia and elevated migration activities.

1. Torre, L.A., et al., Global cancer statistics, 2012. CA Cancer J Clin, 2015. 65(2): p. 87-108.
2. Wroblewski, L.E., R.M. Peek, Jr., and K.T. Wilson, Helicobacter pylori and gastric cancer: factors that modulate disease risk. Clin Microbiol Rev, 2010. 23(4): p. 713-39.
3. Correa, P., Human gastric carcinogenesis: a multistep and multifactorial process--First American Cancer Society Award Lecture on Cancer Epidemiology and Prevention. Cancer Res, 1992. 52(24): p. 6735-40.
4. Sipponen, P. and B.J. Marshall, Gastritis and gastric cancer. Western countries. Gastroenterol Clin North Am, 2000. 29(3): p. 579-92, v-vi.
5. Crusz, S.M. and F.R. Balkwill, Inflammation and cancer: advances and new agents. Nat Rev Clin Oncol, 2015. 12(10): p. 584-96.
6. Hu, B., et al., Gastric cancer: Classification, histology and application of molecular pathology. J Gastrointest Oncol, 2012. 3(3): p. 251-61.
7. Cancer Genome Atlas Research, N., Comprehensive molecular characterization of gastric adenocarcinoma. Nature, 2014. 513(7517): p. 202-9.
8. Wang, K., et al., Whole-genome sequencing and comprehensive molecular profiling identify new driver mutations in gastric cancer. Nat Genet, 2014. 46(6): p. 573-82.
9. Wang, K., et al., Exome sequencing identifies frequent mutation of ARID1A in molecular subtypes of gastric cancer. Nat Genet, 2011. 43(12): p. 1219-23.
10. Deng, N., et al., A comprehensive survey of genomic alterations in gastric cancer reveals systematic patterns of molecular exclusivity and co-occurrence among distinct therapeutic targets. Gut, 2012. 61(5): p. 673-84.
11. Bang, Y.J., et al., Trastuzumab in combination with chemotherapy versus chemotherapy alone for treatment of HER2-positive advanced gastric or gastro-oesophageal junction cancer (ToGA): a phase 3, open-label, randomised controlled trial. Lancet, 2010. 376(9742): p. 687-97.
12. Doshi, S., et al., Rilotumumab exposure-response relationship in patients with advanced or metastatic gastric cancer. Clin Cancer Res, 2015. 21(11): p. 2453-61.
13. Malumbres, M. and M. Barbacid, RAS oncogenes: the first 30 years. Nat Rev Cancer, 2003. 3(6): p. 459-65.
14. Cox, A.D. and C.J. Der, Ras history: The saga continues. Small GTPases, 2010. 1(1): p. 2-27.
15. Scolnick, E.M., et al., Studies on the nucleic acid sequences of Kirsten sarcoma virus: a model for formation of a mammalian RNA-containing sarcoma virus. J Virol, 1973. 12(3): p. 458-63.
16. Shih, C. and R.A. Weinberg, Isolation of a transforming sequence from a human bladder carcinoma cell line. Cell, 1982. 29(1): p. 161-9.
17. Vetter, I.R. and A. Wittinghofer, The guanine nucleotide-binding switch in three dimensions. Science, 2001. 294(5545): p. 1299-304.
18. Cox, A.D., et al., Drugging the undruggable RAS: Mission possible? Nat Rev Drug Discov, 2014. 13(11): p. 828-51.
19. Hunter, J.C., et al., Biochemical and Structural Analysis of Common Cancer-Associated KRAS Mutations. Mol Cancer Res, 2015. 13(9): p. 1325-35.
20. Ostrem, J.M., et al., K-Ras(G12C) inhibitors allosterically control GTP affinity and effector interactions. Nature, 2013. 503(7477): p. 548-51.
21. Singh, A., et al., TAK1 inhibition promotes apoptosis in KRAS-dependent colon cancers. Cell, 2012. 148(4): p. 639-50.
22. Barbie, D.A., et al., Systematic RNA interference reveals that oncogenic KRAS-driven cancers require TBK1. Nature, 2009. 462(7269): p. 108-12.
23. Costa-Cabral, S., et al., CDK1 Is a Synthetic Lethal Target for KRAS Mutant Tumours. PLoS One, 2016. 11(2): p. e0149099.
24. Ying, H., et al., Oncogenic Kras maintains pancreatic tumors through regulation of anabolic glucose metabolism. Cell, 2012. 149(3): p. 656-70.
25. Son, J., et al., Glutamine supports pancreatic cancer growth through a KRAS-regulated metabolic pathway. Nature, 2013. 496(7443): p. 101-5.
26. Serao, N.V., et al., Cell cycle and aging, morphogenesis, and response to stimuli genes are individualized biomarkers of glioblastoma progression and survival. BMC Med Genomics, 2011. 4: p. 49.
27. Frank, B., et al., Association of a common AKAP9 variant with breast cancer risk: a collaborative analysis. J Natl Cancer Inst, 2008. 100(6): p. 437-42.
28. Liu, P., et al., Identification of somatic mutations in non-small cell lung carcinomas using whole-exome sequencing. Carcinogenesis, 2012. 33(7): p. 1270-6.
29. Chen, K., et al., Mutational landscape of gastric adenocarcinoma in Chinese: implications for prognosis and therapy. Proc Natl Acad Sci U S A, 2015. 112(4): p. 1107-12.
30. Cheung, H.W., et al., Systematic investigation of genetic vulnerabilities across cancer cell lines reveals lineage-specific dependencies in ovarian cancer. Proc Natl Acad Sci U S A, 2011. 108(30): p. 12372-7.
31. Singh, A., et al., A gene expression signature associated with "K-Ras addiction" reveals regulators of EMT and tumor cell survival. Cancer Cell, 2009. 15(6): p. 489-500.
32. Xia, L., et al., Effects of epidermal growth factor on the growth of human gastric cancer cell and the implanted tumor of nude mice. World J Gastroenterol, 2002. 8(3): p. 455-8.
33. Zhang, J., et al., Discovery of co-occurring driver pathways in cancer. BMC Bioinformatics, 2014. 15: p. 271.
34. Hewitt, L.C., et al., KRAS, BRAF and gastric cancer. Translational Gastrointestinal Cancer, 2015. 4(6): p. 429-447.
35. Stolze, B., et al., Comparative analysis of KRAS codon 12, 13, 18, 61, and 117 mutations using human MCF10A isogenic cell lines. Sci Rep, 2015. 5: p. 8535.
36. Mortazavi, F., et al., Significance of KRAS/PAK1/Crk pathway in non-small cell lung cancer oncogenesis. BMC Cancer, 2015. 15: p. 381.
37. Kim, R.K., et al., Activation of KRAS promotes the mesenchymal features of basal-type breast cancer. Exp Mol Med, 2015. 47: p. e137.
38. Nijman, S.M., Synthetic lethality: general principles, utility and detection using genetic screens in human cells. FEBS Lett, 2011. 585(1): p. 1-6.
39. Zang, Z.J., et al., Exome sequencing of gastric adenocarcinoma identifies recurrent somatic mutations in cell adhesion and chromatin remodeling genes. Nat Genet, 2012. 44(5): p. 570-4.