Gastric cancer is the second leading cause of cancer death worldwide and in China. The mechanism of gastric carcinogenesis is not fully understood. Epigenetic studies indicated that inactivation of tumor suppressor genes by DNA hypermethylation plays a crucial role in the progression of gastric cancer. Epigenetic inactivation of secreted frizzled-related protein (SFRP 1) by methylation plays a pivotal role on the development of various cancers. However, the role of SFRP family genes in gastric cancer remains largely unknown. We aimed to characterize the epigenetic abnormalities and discover novel biomarkers for early detection of gastric cancer. We investigated the epigenetic alterations in gastric adenocarcinoma by microarray based analysis and gene promoter hypermethylation. Based of the microarray data, we determined the functional significance and frequency of SFRP family genes hypermethylation in human gastric cancer. We screened the mRNA expression and methylation status of the SFRP family members in human gastric cancer cell lines and primary gastric cancer samples. Demethylation study of SFRP family genes were done by treating gastric cancer cell lines with 5'Aza. The biological effects of SFRP were analyzed by flow cytometry, cell viability assay and tumor growth in nude mice. SFRP1, 2, 4 and 5 were undetectable in 100% (7/7), 100% (7/7), 42.8% (3/7) and 85.7% (6/7) of gastric cancer cell lines, respectively. However, only SFRP2 showed significant down-regulation in gastric cancer compared with adjacent non-cancer samples (P<0.01). Treatment with demethylation agent, 5'-Aza, restored the expression of SFRP2 in all 7 cancer cell lines. Promoter hypermethylation of SFRP2 was detected in 73.3% of primary gastric cancer samples and 20% of adjacent non-cancer tissue (P<0.01). Bisulfite sequencing confirmed the density of promoter methylation in cell line, primary gastric cancer tissue and their adjacent non-cancer tissue. Transfection of SFRP2 induced cell apoptosis, inhibited proliferation in vitro and suppressed tumor growth in vivo. Furthermore, SFRP2 methylation was detected in 37.5% of samples showing intestinal metaplasia. Methylated SFRP2 was also detected in 66.7% of serum samples from cancer patients but not in normal controls. Epigenetic inactivation of SFRP2, but not SFRP1, SFRP4 and SFRP5 is a common and early event of carcinogenesis. Hence, detection of SFRP2 methylation in serum may have diagnostic value in gastric cancer patients. / by Cheng, Yuen Yee. / Adviser: FKL Chan. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 0803. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 165-179). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / School code: 1307.

Array comparative genomic hybridization (array-CGH) was used in this study to analyze the chromosomal aberrations in 9 gastric cancer cell lines. Our results showed good concordance with those of conventional CGH. We correlated the results from array-CGH with expression profiling and found some novel and independent target genes which deserved further confirmation. / Gastric cancer is one of the most common malignancies worldwide and is the second most frequent cause of cancer related death. A variety of genetic and epigenetic aberrations underlie development abnormality of gastric cancer. / Taken together, our findings supported YAP1 is a functional oncogene in gastric cancer. We provided the first evidence that YAP1 exerted the oncogenic function by enhancing the capacity to activate the early response gene pathway. YAP1 could be a prognostic biomarker and potential therapeutic target for gastric cancer. / The study was focused on the putative oncogene Yes-associated Protein 1 (YAP1) located in 11q22.1. Up-regulation of YAP1 was observed in 92.3% of gastric cancer by immunohistochemistry (IHe) on gastric cancer tissue microarrays. YAP1 nuclear accumulation correlated with cancer specific survival. In addition, multivariate Cox regression showed that YAP1 was an independent predictor of short disease specific survival time for patients with early stage gastric cancer (P=0.042) in addition to T stage ( P=O.038). Knockdown YAP1 in gastric cancer cell lines MKN1 and AGS resulted in a significant reduction in proliferation, anchorage-dependent colony formation, cell invasion and cell motility. Ectopic YAP1 expression in MKN45 cells promoted anchorage-independent colony formation, induced a more invasive phenotype and accelerated cell growth both in vitro and in vivo. Microarray analysis highlighted the alteration of MAPK pathway by YAP1. We confirmed a constitutive activation of RAF/MEKJERK in YAP1-expressing MKN45 cells and further demonstrated that YAP1 enhanced serum/EGF induced c-Fos expression in gastric cancer cells. Furthermore, we demonstrated that ectopic MST1 promoted phosphorylation and cytoplasmic translocation of YAP1 and subsequently quenched the oncogenic function of YAP1 in the nucleus. / Kang, Wei. / "December 2010." / Adviser: To Kai-fai. / Source: Dissertation Abstracts International, Volume: 73-04, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 175-185). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

研究背景及目的：EB病毒(EBV)相關性胃癌的發病率約占胃癌的10%。近年來，越來越多的研究表明， EBV相關性胃癌的腫瘤抑制基因發生異常甲基化。然而，EBV的感染對全基因組DNA甲基化的影響尚不清楚。本研究通過分析EBV感染的細胞中全基因組DNA甲基化的情況，篩選出因EBV感染而發生甲基化的基因，並闡明靶基因在胃癌發生過程的作用。 / 方法：本研究應用穩定轉染EBV的胃癌細胞AGS (AGS-EBV)和無EBV轉染的AGS細胞為模型。採用高解析度的甲基化DNA免疫共沉澱晶片技術(MeDIP-chip)比較AGS-EBV 和AGS全基因組DNA甲基化的變化，並根據基因本體論(GO)，對EBV誘導的甲基化基因進行分類。採用RT-PCR，去甲基化處理及亞硫酸氫鈉測序(BGS)等方法驗證EBV誘導的甲基化基因。同時，採用基因敲除和過表達方法體外研究靶基因的生物學功能：通過細胞活力實驗和集落形成實驗判斷靶基因對細胞增殖的影響；通过流式细胞技术、伤口愈合实验及侵袭实验研究筛选到的靶基因生长抑素受体1（SSTR1）的功能；此外，还通過腫瘤通路基因PCR晶片分析靶基因調控的下游腫瘤相關基因。 / 结果：EBV編碼的小RNA(EBER)原位雜交方法和EBV潛伏期膜蛋白(LMP2A)的表達均證實AGS-EBV細胞中確實存在EBV的感染。和AGS細胞相比，發現AGS-EBV細胞中DNA甲基轉移酶3b(DNMT3b)的表達和活性顯著增加。AGS細胞中， LMP2A過表達後，DNMT3b的表達和活性也顯著增加。通過MeDIP-chip篩選出AGS-EBV中1,065甲基化有差異的基因，其中886基因為高甲基化。GO分析結果表明這些高甲基化基因參與KEGG信號通路。其中，六個新的高甲基化基因(MDGA2, IL15RA, SCARF2, EPHB6, SSTR1 和 REC8)在AGS-EBV細胞中的表達低於AGS；經過去甲基化處理之後，這些基因的表達水準有顯著增加。 / 通過深入研究生長抑素受體1(SSTR1)的生物學功能，發現：敲除SSTR1 能促進胃癌細胞的增殖和集落形成；通過调节G1/S期的調節因子，加快細胞進入S期，顯著增加S期的細胞數目。此外，胰腺癌細胞PANC1細胞中，SSTR1的過表達，也進一步證實SSTR1確實是一種腫瘤抑制基因。腫瘤通路基因PCR晶片結果顯示SSTR1通過促進細胞週期抑制因數(包括p15，p16，p21和p27)的表達，同時抑制CDC25A 和Myc的表達，發揮抑制增殖作用，導致細胞週期停滯在G1期，減少細胞增殖。SSTR1也通過減少凋亡相關基因的表達參與細胞凋亡的過程。此外，SSTR1還能顯著下調遷移相關基因的表達。這些結果表明，在EB病毒相關胃癌的發生過程中，SSTR1通過調節細胞週期、凋亡及遷移的有關基因，進而抑制細胞增殖，減少細胞的遷移和轉移。 / 结论：AGS感染EBV後，通過LMP2A促進DNMT3b的表達，激活DNMT3b的活性，導致886個腫瘤相關基因发生甲基化。SSTR1是一種EBV誘導的新的甲基化基因，在胃癌中具有抑制腫瘤的特性。研究表明， 由EBV誘導的SSTR1所具有的表觀遺傳學抑制作用參與EB病毒相關性胃癌的發病機制。 / Background and Aims: Epstein-Barr virus (EBV)-associated gastric cancer (GC) accounts for about 10% of all GCs. Accumulating evidences revealed aberrant rmethylation of tumor suppressor genes in EBV-associated GCs. However, the effect of EBV infection on the genome-wide aberrant DNA methylation remains unclear. We aim to profile the genome-wide EBV-associated hypermethylation in EBV-infected cells, to identify EBV-associated methylated genes and to elucidate their function in gastric carcinogenesis. / Methods: The cell model of gastric cancer AGS cells with or without stable EBV infection was used in this study. Genome-wide DNA methylation profiles were compared between AGS-EBV and AGS cells by high resolution Methyl-DNA immunoprecipitation microarry (MeDIP-chip) assay. EBV-associated methylated genes were classified according to gene ontology (GO). The novel EBV-associated methylated candidates were validated using bisulfite genomic sequencing (BGS), RT-PCR, and demethylation treatment. Biological function of one of the candidate genes (Somatostatin Receptor 1, SSTR1) was studied in vitro using gene knockdown and over-expression approaches simultaneously. Effects of SSTR1 expression on gastric cancer cell was measured by cell viability assay, colony formation assay, flow cytometry, wound-healing assay and invasion assay. Gene modulation by SSTR1 in human cancer pathways was assessed by cancer pathway PCR array. / Results: EBV infection was confirmed by EBER in situ hybridization. LMP2A expression was detected in AGS-EBV cells but not in EBV negative AGS cells. Expression and activity of DNMT3b was found to be significantly increased in AGS-EBV cells compared to AGS cells. Ectopic expression of LMP2A in AGS enhanced the expression and activity of DNMT3b. MeDIP-chip profiling identified a total of 1,065 genes differentially methylated by EBV infection (fold changes ≥2, P < 0.05) (fold-changes 2.4365.2). Gene ontology analysis indicated the enrichment of hypermethylated genes involving in important KEGG pathways. Notably, in addition to higher methylation levels confirmed by BGS, six novel hypermethylated genes (MDGA2, IL15RA, SCARF2, EPHB6, SSTR1 and REC8) were down-regulated in AGS-EBV cells as compared with AGS cells. Furthermore, demethylation treatment increased transcription levels of the six genes in AGS-EBV cells. / The biological function of SSTR1 gene was further investigated. Knockdown of SSTR1 in GC cells increased cell proliferation (P < 0.05) and colony formation ability (P < 0.01), and markedly increased cells in S phase through regulating G1/S phase mediators. Overexpression of SSTR1 in PANC1 cell line further confirmed that SSTR1 indeed was a tumor suppressor gene. Analysis of SSTR1 regulation of cancer pathway demonstrated that SSTR1 exerted antiproliferative effect by inducing cyclin-dependent inhibitors (p15, p16, p21 and p27) and inhibiting cell divison cycle 25 homolog A (CDC25A) and Myc, resulting in cell cycle arrest in G1 phase and reduction of cell proliferation. SSTR1 also took part in proliferation by decreasing expression of apoptosis regulators. Moreover, SSTR1 significantly downregulated the expression of migration-related genes, including ITGA1, ITGA2, ITGA3, ITGB5, IL8, MMP1 and PLAUR. These findings suggest that SSTR1 inhibits proliferation and reduces cell migration/invasion in gastric cancer by deregulating genes invloved in the regulation of cell cycle, survival/apoptosis and migration. / Conclusions: EBV infection in AGS cells induces genome-wide aberrant hypermethylation of 886 genes which involved in important cancer-related pathways. EBV-associated methylation is mediated by activation of DNMT3b through LMP2A. We identified and functionally characterized a novel EBV-associated methylated gene SSTR1 which exerted anti-tumor properties in GC. Epigenetic silencing of SSTR1 associated with EBV infection contributes to the pathogenesis of EBV-associated GC. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Zhao, Junhong. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 129-141). / Abstract also in Chinese. / ABSTRACT --- p.i / 摘 要 --- p.iv / Acknowledgements --- p.vi / Publications --- p.vii / Research articles --- p.vii / Conference abstracts --- p.viii / Table of contents --- p.x / list of tables --- p.xiii / list of figures --- p.xiv / list of abbreviations --- p.xvi / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- General introduction --- p.1 / Chapter 1.2 --- Gastric Cancer --- p.3 / Chapter 1.2.1 --- Eipdemiology of Gastric Cancer --- p.4 / Chapter 1.2.2 --- Pathology of Gastric Cancer --- p.8 / Chapter 1.2.3 --- Risk Factors for Gastric Cancers --- p.11 / Chapter 1.3 --- Epstein-Barr Virus-associated Gastric Cancer (EBVaGC) --- p.15 / Chapter 1.3.1 --- Historical Discovery and Harm of EBV --- p.15 / Chapter 1.3.2 --- Molecular Biology of EBV --- p.16 / Chapter 1.3.3 --- Latent and Lytic Infection of EBV --- p.18 / Chapter 1.3.4 --- EBV Products --- p.18 / Chapter 1.3.5 --- EBV-associated gastric cancer (EBVaGC) --- p.28 / Chapter 1.4 --- EBV-induced Epigenetic Alteration in Gastric Carcinogenesis --- p.36 / Chapter 1.4.1 --- Cytosine Methylation and CpG Island --- p.36 / Chapter 1.4.2 --- DNA Methylation in Gastric Cancer --- p.39 / Chapter 1.5 --- How to identify EBV-induced promoter methylation in gastric cancer --- p.45 / Chapter 1.5.1 --- Methylated DNA Immunoprecipitation (MeDIP) --- p.48 / Chapter 1.5.2 --- Combined Bisulfite Restriction Analysis (COBRA) --- p.49 / Chapter 1.5.3 --- Bisulfite Genomic Sequencing --- p.49 / Chapter 1.5.4 --- Pyrosequencing --- p.49 / Chapter Chapter 2 --- Materials and Methods --- p.51 / Chapter 2.1 --- Materials --- p.51 / Chapter 2.1.1 --- Cancer Cell Lines and Culture Condition --- p.51 / Chapter 2.1.2 --- Primary GC Samples --- p.52 / Chapter 2.2 --- EBV Encoded Nuclear RNA (EBER) in situ Hybridization (EBER-ISH) --- p.52 / Chapter 2.3 --- Western Blot Analysis --- p.53 / Chapter 2.4 --- Plasmid and Transfection --- p.56 / Chapter 2.4.1 --- Plasmid Construction and Extraction --- p.56 / Chapter 2.4.2 --- Plasmid Transfection --- p.59 / Chapter 2.5 --- Gene Expression Analysis --- p.59 / Chapter 2.5.1 --- Purification of Total RNA (RNeasy Kit, Qiagen) --- p.59 / Chapter 2.5.2 --- cDNA Reverse Transcription --- p.60 / Chapter 2.5.3 --- Semi-Quantitative PCR --- p.62 / Chapter 2.5.4 --- Quantitative Real-Time PCR (qRT-PCR) --- p.64 / Chapter 2.6 --- DNMT1 and 3b Activity Assay --- p.64 / Chapter 2.7 --- DNA Methylation Analysis --- p.64 / Chapter 2.7.1 --- Genomic DNA Extraction --- p.64 / Chapter 2.7.2 --- Genome-wide Profiling of EBV-associated DNA Methylation by MeDIP-chip --- p.65 / Chapter 2.7.3 --- Bioinformatics Analysis --- p.66 / Chapter 2.7.4 --- CpG Island Prediction and Analysis of the Targets’ Promoter Region --- p.66 / Chapter 2.7.5 --- DNA Sodium Bisulfite Modification --- p.67 / Chapter 2.7.6 --- Target Gene Methylation in GC Cell Lines --- p.67 / Chapter 2.7.7 --- Bisulfite Pyrosequencing Analysis in GC Tissue Samples --- p.70 / Chapter 2.8 --- Biological Function Analysis of SSTR1 --- p.72 / Chapter 2.8.1 --- Cell Proliferation Assay for Stable Transfection --- p.72 / Chapter 2.8.2 --- Colony Formation Assay --- p.72 / Chapter 2.8.3 --- Cell Cycle Analysis Assay --- p.72 / Chapter 2.8.4 --- Cell Migration Analysis --- p.73 / Chapter 2.8.5 --- Invasion Analysis --- p.73 / Chapter 2.8.6 --- Human Cancer Pathway Finder RT2 Profiler PCR Array Analysis --- p.74 / Chapter 2.9 --- Statistical Analysis --- p.76 / Chapter Charpter 3 --- results --- p.77 / Chapter 3.1 --- EBV Infection in AGS-EBV Cell Model --- p.77 / Chapter 3.2 --- Activation of DNMT3b in AGS-EBV Cells --- p.80 / Chapter 3.3 --- LMP2A Induced DNMT3b Activity in AGS Cells --- p.82 / Chapter 3.4 --- Genome-wide Profiling of DNA Methylation Associated with EBV Infection Using MeDIP-chip --- p.84 / Chapter 3.5 --- EBV-associated Cancer Pathways Defined by EBV-associated Promoter Methylated Genes --- p.86 / Chapter 3.6 --- CpG Hypermethylation and Transcriptional Silencing of EBV-associated Methylated Genes in AGS-EBV Cells --- p.88 / Chapter 3.7 --- Bioinformatics Analysis of SSTR1 Using University of California Santa Cruz Genome Bioinformatics (UCSC) Database and CpG Island Searcher --- p.93 / Chapter 3.8 --- COBRA Analysis of SSTR1 Promoter Methylation in GC Cell Lines --- p.93 / Chapter 3.9 --- Frequent SSTR1 Hypermethylation was Associated with EBV Positive Primary Gastric Cancer --- p.96 / Chapter 3.10 --- SSTR1 was Down-regulated in GC Cell Lines through RNA Interference --- p.103 / Chapter 3.11 --- SSTR1 Knockdown Induced Cell Proliferation in GC Cell Lines --- p.105 / Chapter 3.12 --- SSTR1 Knock-down Promoted Cells to Enter into S Phase --- p.108 / Chapter 3.13 --- SSTR1 Knock-down Increased the Migration Ability of GC --- p.110 / Chapter 3.14 --- SSTR1 Knock-down Promoted Cell Invasion --- p.112 / Chapter 3.15 --- Ectopic Expression of SSTR1 Inhibited Proliferation and Clonogenicity in PANC1 Cancer Cells --- p.114 / Chapter 3.16 --- Identification of Genes Modulated by SSTR1 --- p.116 / Chapter Chapter 4 --- Discussion --- p.119 / Chapter Chapter 5 --- Limitation of the study --- p.127 / ConclusionS --- p.128 / Reference --- p.129

Array-CGH analysis of the gastric cancer cell lines suggested that TXNIP loci were intact, suggesting that allelic loss might not be the major mechanism responsible for the downregulation of TXNIP in these cells. Furthermore, our data suggested that promoter hypermethylation of TXNIP may not be an important epigenetic mechanism that regulate the silencing of this gene. Chromatin immunoprecipitation (ChIP) assay revealed that SAHA induced hyperacetylation of histone H3 and H4 at the 5' flanking region of TXNIP gene, suggesting SAHA could promote TXNIP gene transcription via modification of histones located at the promoter region. Our data revealed that the loss or reduced expression of TXNIP in gastric cancer cells is associated with epigenetic histone acetylation mechanism. / Gastric cancer is a common cancer especially in Asian countries and is associated with high morbidity and mortality. Epigenetic inactivation of tumor suppressor is a common mechanism involved in carcinogenesis of a variety of human cancers and recent evidence suggested that targeting epigenetic modifications may be an approach to combat cancer. Our group and others have demonstrated frequent promoter methylation of cancer related genes in gastric cancer. In this study, we aim to identify cancer associated genes regulated by another important epigenetic mechanism, namely histone acetylation. / In addition, we demonstrated that over-expression of TXNIP significantly reduced cell migration ability and inhibited cell invasiveness in gastric cancer cells. Furthermore, absence or reduced expression of TXNIP in gastric cancer was associated with diffuse-type gastric cancer, advanced stage disease and predicted a poor disease specific survival. The findings supported that TXNIP is a functional tumor suppressor gene and may be a potential biomarker in gastric cancer. / We analyzed 25 paired gastric cancer and non-cancer gastric mucosa and found that expression of TXNIP mRNA level was reduced in 84% of gastric cancer and was significantly downregulated as compared to the paired non-cancer gastric tissues (p=0.002). Expression of TXNIP protein by western blot was down-regulated in 3 out of 5 cases. Furthermore, by immunohistochemical staining of TXNIP in tissue array containing 150 cases of gastric cancer also showed frequent down-regulation of TXNIP expression and &sim;26% with complete lack of TXNIP expression. / We first showed that suberoylanilide hydroxamic acid (SAHA), a well known histone deacetylase inhibitor, has anti-proliferative effect in a panel of gastric cancer cell lines (MKN1, MKN7, MKN28, MKN45, SNU1, SNU16, AGS, N87 and KatoIII cells). We compared gene expression profiles of SAHA treated vs control AGS cells to identify a set of genes that were differentially upregulated by SAHA treatment. Based on our microarray analysis in nine gastric cancer cell lines (MKN1, MKN7, MKN28, MKN45, SNU1, SNU16, AGS, N87 and KatoIII) and normal gastric tissues, a set of commonly downregulated genes in gastric cancer cells was elucidated. Analysis of these data sets with subsequent confirmation using real-time PCR analysis, genes that were downregulated in gastric cancer cells but upregulated upon SAHA treatment were identified. Among these selected genes, Thioredoxin Interacting Protein (also known as VDUP-1/TBP2/TXNIP ) was down-regulated in all cancer cell lines tested, and its protein expression was significantly induced by SAHA treatment in a numbers of gastric cancer cell lines including AGS, MKN1, MKN45, N87 and KatoIII. Thus, we focused on the TXNIP in the subsequent studies. / Tang, Angie. / Adviser: To Ka Fai. / Source: Dissertation Abstracts International, Volume: 72-04, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 180-202). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2005. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 4 uppsatser.

Diss. (sammanfattning) Linköping : Univ., 2004. / Härtill 5 uppsatser.

Introduction: Worldwide, Gastric Cancer (GC) is the fourth cancer in incidence and the second most common cause of cancer death. Because it is asymptomatic in the early stages, it is often diagnosed in advanced stages. HER2 gene expression has been identified in about 20% of GC. Its expression is associated with a worse prognosis for GC patients. Objectives: To study HER2 immunoexpression in specimens of gastric adenocarcinoma and its association with histological classification and anatomical location. Patients and methods: We conduct a cross-sectional study, where we analyzed HER2 immunoexpression in 48 specimens of gastric adenocarcinoma. We use avidin-biotin method with primary antibody peroxidase C-erb B2, clone EP1045Y (Biocare Medical, USA). Results: We found seven positive cases. HER2 was expressed in 5 intestinal type and 2 in the intestinal component of mixed type. There was no expression of HER2 in diffuse type. HER2 expression was associated with the intestinal component of gastric adenocarcinoma (p = 0.003). Regarding the anatomical site, 1 in 6 (16.6%) proximal cases was positive for HER2, and 6 in 42 (14.28%) distal were positive for HER2. We did not find an association between HER2 expression and the anatomical site of GC. Conclusion: HER2 immunoexpression was found in 14.6% of the sample and it showed significant association with Lauren's intestinal subtype. / Introdução: O Câncer Gástrico (CG) ocupa o quarto lugar em incidência no mundo, sendo a segunda causa de óbito por neoplasia maligna. Por ser assintomático nas fases iniciais, na maioria das vezes, é diagnosticado em fases avançadas. A expressão do gene HER2 tem sido identificada em cerca de 20% dos CG, e sua hiper-expressão está associada a um pior prognóstico nestes pacientes. Objetivo: Investigar a expressão imunoistoquímica do HER2 em espécimes de adenocarcinoma gástrico, e sua relação com a classificação histológica e localização anatômica. Pacientes e métodos: Estudo transversal, retrospectivo, onde foi analisada a expressão imunoistoquímica para o HER2, em uma amostra de 48 espécimes de CG, através da técnica de imunoistoquímica, pelo método avidina-biotina-peroxidase, utilizando anticorpo primário C-erb B2, clone EP1045Y (Biocare Medical, USA). Resultados: Foram encontrados 7 casos com expressão positiva de HER2; destes, 5 eram casos de adenocarcinoma do tipo intestinal e 2 eram casos do tipo misto, porém, nestes, a expressão ocorreu no componente intestinal, o que determinou uma associação significante da expressão de HER2 com o componente intestinal do adenocarcinoma gástrico (p=0,003). Quanto ao sítio anatômico, dos 6 casos proximais, somente 1 (16,6%) foi positivo para o HER2, e nos 42 casos distais 6 (14,28%) foram positivos para o HER2. Não foi demonstrada associação da expressão de HER2 com o sítio anatômico das lesões. Conclusão: A expressão de HER2 ocorreu em 14,6% da amostra, associada significativamente ao subtipo intestinal de Lauren.

INTRODUÇÃO: o câncer de estômago já foi, mundialmente, a neoplasia com maior ocorrência na população. Ao longo das décadas, a incidência deste câncer apresenta tendência de decréscimo significativo, sendo que, atualmente, é o quinto tumor maligno mais frequente no mundo. A mortalidade não acompanhou a tendência de decréscimo na mesma velocidade e ainda é considerada a terceira principal causa de morte por câncer. O Brasil acompanhou a tendência mundial, registrando o declínio significativo da incidência e da mortalidade. O município de São Paulo apresenta as mais altas taxas de incidência e mortalidade do país. Apesar disso, existem poucos estudos de tendências de incidência dessa neoplasia para São Paulo e este é o primeiro estudo que investiga as tendências de incidência e mortalidade por sexo, por faixas etárias e por tipo histológico. OBJETIVO: analisar as tendências dos coeficientes de incidência e mortalidade do câncer de estômago, segundo sexo, faixa etária e tipo histológico pela classificação de Lauren. MÉTODOS: estudo ecológico de séries temporais. Foram analisados os novos casos de câncer de estômago, diagnosticados no período de 1997 a 2011, no município de São Paulo, cadastrados no Registro de Câncer de Base Populacional de São Paulo, e os óbitos por câncer de estômago do período de 1980 a 2011, de residentes no Município de São Paulo, obtidos do site do Departamento de Informática do Sistema Único de Saúde (DATASUS) do Ministério da Saúde. Foram feitas análises de séries temporais por sexo, faixa etária e tipo histológico utilizando a classificação de Lauren. Os coeficientes brutos e padronizados foram calculados e utilizados nas análises de tendências, através dos modelos de regressão linear e do cálculo da mudança percentual anual (APC). RESULTADOS: foram analisados 24.512 casos incidentes e 31.215 óbitos. Houve redução da incidência (APC -8,3 por cento em homens e -6,5 por cento em mulheres) e da mortalidade (APC -2,3 por cento em homens e -2,5 por cento em mulheres). Houve tendência de queda em todas as faixas etárias, com exceção da faixa etária mais jovem (20-29 anos), que apresentou estabilidade da incidência e da mortalidade. A estabilidade na faixa etária mais jovem também foi identificada nos tipos intestinal e difuso. O tipo difuso apresentou estabilidade também nas faixas etárias: 30-39, 40-49 e 80 anos do sexo feminino. CONCLUSÃO: São Paulo acompanhou a tendência mundial de decréscimo na incidência e na mortalidade, entretanto, a mesma tendência não foi observada entre adultos jovens, principalmente a faixa etária de 20 a 29 anos. Atenção especial deve ser dada ao tipo difuso, que não apresentou queda na tendência de incidência do câncer de estômago para as mulheres de 20 a 49 anos. / INTRODUCTION: the stomach cancer was once considered as the most incident neoplasm worldwide. Over the decades, the stomach cancer incidence has been showing a significant decreasing trend, and is currently the fifth most common malignancy in the world. Mortality has not followed this decreasing trend at the same speed and is still considered the third leading cause of cancer death. Brazil follows this global trend, having a significant decline both in incidence and mortality. Across the regions of Brazil, the city of São Paulo has one of the highest incidence and mortality rates. Nevertheless, there are few studies on trends of this neoplasm in Sao Paulo and this is the first study to investigate the trends of incidence and mortality by sex, age group and histological type. OBJECTIVE: to analyze the trends in stomach cancer incidence and mortality, according to gender, age group and histological type of Lauren\'s classification. METHODS: this is an ecological time-series study. We analyzed the new cases of stomach cancer diagnosed between 1997 and 2011 in São Paulo registered in the Population Based Cancer Registry of São Paulo and deaths from stomach cancer from 1980 to 2011, in the city of São Paulo, obtained from the Ministry of Health website - Department of the Unified Health System (DATASUS). Time series analyzes were performed by gender, age group and histological type using the Lauren classification of intestinal-type and diffuse type. Crude and agestandardized rates were calculated and used in time trend analysis, through linear regression models and the annual percentage change (APC). RESULTS: we analyzed 24,512 incident cases and 31,215 deaths. There was a reduction in the incidence (APC -8.3 per cent men and -6.5 per cent women) and mortality (APC -2.3 per cent men and 2.5 per cent women). A decreasing trend was observed for all age groups, except for the youngest (20-29 years) for which stability was observed. Both intestinal and diffuse types remained stable in the youngest age group. The diffuse type was stable also in the age groups: 30-39, 40-49 and 80 years female. CONCLUSION: São Paulo followed the global trend of decrease in incidence and mortality, however, the same trend was not observed among young adults, especially the age group 20-29 years. Special attention should be given to diffuse type that showed no reduction in the incidence trend of stomach cancer for women 20-49 years female.

INTRODUÇÃO: O câncer gástrico precoce que invade a submucosa pode apresentar acometimento linfonodal em torno de 20% dos casos. O tratamento cirúrgico clássico com gastrectomia e linfadenectomia D2 é um procedimento não isento de mortalidade e morbidade. Determinar quais pacientes têm maior risco de acometimento linfonodal permitiria tratamentos com menores complicações. Recentemente diversos autores relatam maior expressão imuno-histoquímica de p53 e p21ras em tumores avançados e com pior prognóstico. Tem sido relatada também perda da expressão de p21waf1, p27kip1 e p16ink4a nos tumores avançados e algumas publicações relatam também relação entre a expressão dos marcadores e acometimento linfonodal. MÉTODOS: Foram estudados retrospectivamente 81 pacientes submetidos à gastrectomia com linfadenectomia D2 no período de 1971 a 2004 no Serviço de Cirurgia do Estômago e Intestino Delgado do Departamento de Gastroenterologia do HC-FM/USP. Os blocos de parafina contendo fragmentos dos tumores foram recuperados e novo exame histopatológico confirmou o diagnóstico. Selecionaram-se áreas representativas de mucosa normal, mucosa metaplásica e tumor para confecção de novos blocos de tissue microarrays. Foi avaliada a expressão imuno-histoquímica de p21ras, p53, p21waf1/cip1, p27kip1 e p16ink4a nos tecidos. Foram investigadas as correlações entre a expressão dos marcadores e as características clínico-patológicas dos pacientes. A análise da associação entre os dados clínicos e a positividade dos marcadores foi realizada pelo teste Qui-quadrado. RESULTADOS: Na mucosa normal, metaplásica e tumoral p53 apresentou positividade em 53%, 87,3% e 87,1% dos casos respectivamente. Nos mesmos tecidos p21ras apresentou positividade de 85,3%, 86% e 96,8%. Para p16ink4a a positividade foi de 46,3%, 91,1% e 86%. Para p27kip1 a positividade foi de 60%, 94,7% e 95,3%. Para p21waf1/cip1 a positividade foi 32,4%, 72,7% e 71,4%. Todos os tumores tiveram alguma positividade para p53. Os tumores com acometimento linfonodal apresentaram hiper-expressão(+4) de p53 em 47% dos casos contra 17% nos pacientes que não tinham acometimento. Nenhum tumor com positividade para p53 baixa(0 e +1) teve linfonodos acometidos. Nenhum tumor com p21ras negativo apresentou linfonodos acometidos. Nos pacientes com acometimento linfonodal p21ras teve positividade intensa(+2 e +3) em 88% dos casos contra 50% dos casos sem acometimento linfonodal. Houve positividade intensa(+2,+3 e +4) de p21waf1/cip1 em 71% dos tumores com acometimento linfonodal contra 28% nos pacientes sem acometimento. Não observamos perda de expressão de p21waf1, p27kip1 e p16ink4a nos tumores com acometimento linfonodal. Na mucosa normal p16ink4a foi hiper-expresso (+4) em 20% dos casos com infiltração perineural contra 0% nos casos sem acometimento. O mesmo marcador foi hiperexpresso em 50% dos casos com infiltração vascular contra 0% dos casos sem infiltração. Os tumores com padrão de infiltração Sm2 tiveram pouca positividade(0 e +1) de p27kip1 na mucosa normal em 89% dos casos contra 55% dos casos Sm1. CONCLUSÕES: Maior expressão de p53, p21ras e p21waf1/cip1 no tumor teve relação estatística significante com acometimento linfonodal. Ocorre aumento da expressão imuno-histoquímica de todos os marcadores da mucosa normal para o tumor. A maior hiper-expressão de p16ink4a na mucosa normal de pacientes tem relação com infiltração perineural e vascular nos tumores. A expressão dos marcadores é diferente nas raças estudadas. As pacientes do sexo feminino apresentam maior positividade de p21waf1 na mucosa normal. Pacientes com história familiar de câncer gástrico apresentam maior positividade de p16ink4a na mucosa normal, menor positividade de p21waf1/cip1 e p21ras na mucosa metaplásica. Maior positividade na mucosa normal de p21waf1/cip1 relaciona-se a sexo feminino e infiltração tipo Sm1 / INTRODUCTION: Early gastric cancer that invades the submucosa might have a lymphonodal involvement in about 20% of the cases. Gastrectomy and D2 linfadenectomy is a procedure that has presented mortality and morbidity. Determining which patients would have a greater risk of lymphonodal involvement would allow treatments with fewer complications. Recently, several authors reported a greater immunohistochemical expression of p53 and p21ras in advanced tumors with worst prognosis. It has also been reported the expression loss of p21wafl, p27kip1, and p16ink4a in advanced tumors, and, some studies also observed the relationship between the markers expression and lymphonodal involvement. METHODS: Eightyone patients who had undergone gastrectomy with D2 linfadenectomy from 1971 to 2004 were retrospectively studied. A new histopathological exam confirmed the diagnosis. Representative areas of both normal and metaplastic mucosa and of the tumor were selected for obtaining new blocks of tissue microarrays. The immunohistochemical expression of p21ras, p53, p21waf1/cip1, p27kip1 and p16ink4a in the tissues was evaluated. RESULTS: In normal, metaplastic and tumoral mucosa, p53 showed positivity in 53%, 87.3%, and 87.1% of the cases, respectively. In the same tissues, p21ras showed positivity in 85.3%, 86%, and 96.8%, respectively. The positivity of p16ink4a was 46.3%, 91.1%, and 86%, respectively. p27kip1 showed a positivity of 60%, 94.7%, and 95.3%, respectively. p21wafl/cip1 presented a positivity of 32.4%, 72.7%, and 71.4%, respectively. All tumors showed positivity for p53. Tumors with lymphonodal involvement presented hyperexpression (+4) of p53 in 47% of the cases versus 17% in patients who had not showed any involvement. No tumor with low positivity (0 and +1) of p53 showed lymphonodal involvement. No tumor with negative p21ras showed lymphonodal involvement. In patients with lymphonodal involvement, p21ras presented strong positivity (+2 and +3) in 88% of the cases versus 50% of the cases without lymphonodal involvement. There was a strong positivity (+2,+3, and +4) of p21wafl/cip1 in 71% of the tumors with lymphonodal involvement versus 28% in patients without involvement. It was not observed an expression loss of p21waf1, p27kip1 e p16ink4a in tumors with lymphonodal involvement. In normal mucosa, p16ink4a showed a hyper-expression (+4) in 20% of the cases with perineural invasion versus 0% of the cases without invasion. This same marker showed a hyper-expression in 50% of the cases with vascular invasion versus 0% of the cases without invasion. Tumors with Sm2 invasion pattern showed low positivity (0 and +1) of p27kip1 in normal mucosa in 89% of the cases versus 55% of the cases of Sm1 tumors. CONCLUSIONS: Higher expression of p53, p21ras, and p21wafl/cip1 in tumor showed a significant statistical relationship with lymphonodal involvement. A higher hyper-expression of p16ink4a in patients normal mucosa was related to perineural and vascular invasion of tumors