Expression profiling of gastric adenocarcinoma using cDNA array

Abstract

To investigate the expression profile of gastric adenocarcinoma, cDNA array experiments were performed using Atlas Human Cancer 1.2 K Array (Clontech Laboratories, Palo Alto, CA) on nine xenografted and two primary gastric cancer samples. The expression of the tumor samples was compared to that of two normal gastric epithelial tissues. The expression pattern of the primary tumors was similar to that of xenografted tumors. The up-regulated genes had expression ratios ranging from 2.5 to 16, whereas the down-regulated genes had a range from ؊2.5 to ؊16. No variation in gene expression was detected in the analysis of the xenografted tumors versus the primary tumors, indicating that the xenografts represented the primary tumors well. Thirtyeight genes showed altered gene expression in 5 or more samples (>45%). Thirty-one genes were up-regulated and seven genes were down-regulated. The most abundantly upregulated genes (ratio >5) included genes such as S100A4, CDK4, MMP14 and beta catenin. The GIF was markedly downregulated (ratio < ؊10). To confirm our findings, six genes (three up-and three down-regulated) were selected for semiquantitative RT-PCR analysis. The RT-PCR results were consistent with the array findings. Our approach revealed that several genes are abnormally expressed in gastric cancer and found that genes known to interact in several common molecular pathway(s) were consistently altered. © 2001 Wiley-Liss, Inc. Key words: cDNA arrays; gene expression; xenografts; and gastric adenocarcinomasGastric carcinoma (GC) is one of the most common malignancies worldwide and is the second most common cause of cancerrelated death. 1 Overall relative 5-year survival rates are currently less than 20%. Cytogenetic studies of gastric adenocarcinomas are few in number and have failed to identify any consistent or noteworthy chromosomal abnormalities. 2 Comprehensive studies of DNA copy number changes using comparative genomic hybridization (CGH) have revealed alterations in several chromosomal regions. 3-5 Frequent high-level amplifications were noted at 17q and 20q, whereas DNA copy number losses were frequently seen in 4q, 5q, and 9p. However, there are few data on gene expression in gastric cancer. The recent development of cDNA array technology allows the study of gene expression level and gene activation in thousands of genes and sequences. 6,7 The data obtained from the array analysis are expected to uncover novel genes related to cancer development and its clinical behavior. However, tumor sample contamination with normal cells makes analysis of hundreds of genes more difficult and less sensitive. Xenografting of human tumors has been used to produce optimal samples that are enriched for neoplastic cells for subsequent molecular analyses.

Differential gene expression profiles of gastric cancer cells established from primary tumour and malignant ascites

“…Gene expression changes in adhesion molecules, signalling molecules, growth factor receptors, drug metabolism and immune response are likely to contribute to the complexicity of gastric cancer peritoneal dissemination. Overexpression or down-regulation of these genes in highly metastatic cells, as we have shown in this study, is in good concordance with the findings of previous reports (El-Rifai et al, 2001;Hippo et al, 2001) and indicates that gene expression changes in these cells accurately reflects some metastatic characteristics. For example, CD44 and galectin 3 (Hsieh et al, 1999;Moon et al, 2001), genes relevant for cancer metastasis, were up-regulated in peritoneal metastasis.…”

“…Previous reports have shown gene expression profiles in schirrous gastric cancer cell lines as well as xenografts of gastric cancers in nude mice (El-Rifai et al, 2001;Hippo et al, 2001). As we screened more than 21 000 genes, we could select more novel Tables 2 and 3 were singled out according to their function and are discussed in relation to previous reports.…”

HIF-1 is involved in the negative regulation of AURKA expression in breast cancer cell lines under hypoxic conditions

“…Aurora kinase A (AURKA), whose expression is cell cycle dependent, is mainly involved in centrosome maturation, spindle assembly, and chromosome segregation, and it is associated with several co-activators such as BORA, TPX2, Ajuba (JUB), TACC1, and GADD45a that drive the localization, activation, and substrate preference during cell division [9,10]. AURKA is overexpressed in many types of human malignancies, such as breast, bladder, ovarian, colorectal, pancreatic, and gastric cancers [11][12][13]. This overexpression correlates with tumorigenesis, metastasis, and chemoresistance, confirming the pro-survival function of AURKA in cancer cells.…”

Variation in Gene Expression Patterns in Human Gastric Cancers

“…Previous studies have reported expression profiles in small numbers of gastric cancer samples, identifying a few hundred genes that distinguish tumor from normal tissue (El-Rifai et al, 2001;Hippo et al, 2002). However, these studies were too small to distinguish subgroups or identify any genes whose expression may be correlated with clinical outcomes.…”