ONCOGENOMICS Systematic search for gastric cancer-specific genes based on SAGE data: melanoma inhibitory activity and matrix metalloproteinase-10 are novel prognostic factors in patients with gastric cancer PP Aung 1 , N Oue 1 , Y Mitani 1 , H Nakayama 1 , K Yoshida 2 , T Noguchi 3 , AK Bosserhoff 4 and W Yasui ,1 1 Department of Molecular Pathology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan; 2 Department of Surgical Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, Japan; 3 Department of Oncological Science (Surgery II), Oita University Faculty of Medicine, Oita, Japan and 4 Institute of Pathology, University of Regensburg, Regensburg, Germany Gastric cancer (GC) is one of the most common malignancies worldwide. Genes expressed only in cancer tissue will be useful molecular markers for diagnosis and may also be good therapeutic targets. However, little is known about cancer-specific genes, at least in GC. In this study, we searched for GC-specific genes by serial analysis of gene expression (SAGE) data analysis and quantitative reverse transcription (RT)–PCR. Comparing GC SAGE libraries with those of various normal tissues in the SAGEmap database, we identified 54 candidate GC- specific genes. Quantitative RT–PCR analysis of these candidates revealed that APin protein (APIN), taxol resistance-associated gene 3 (TRAG3), cytochrome P450, family 2, subfamily W, polypeptide 1 (CYP2W1), melanoma inhibitory activity (MIA), matrix metallopro- teinase-10 (MMP-10), dickkopf homolog 4 (DKK4), GW112, regenerating islet-derived family, member 4 (REGIV), and HORMA domain-containing 1 (HOR- MAD1) were expressed much more highly in GC than in 14 kinds of normal tissues. Immunohistochemical staining for MIA, MMP-10, and DKK4 was found in 47 (31.1%), 68 (45.0%), and two (1.3%) of 151 GCs, respectively, and staining for both MIA and MMP-10 was correlated with poor prognosis in advanced GC (P ¼ 0.0001 and 0.0141, respectively). Moreover, enzyme-linked immunosorbent assay showed high levels of MMP-10 (65/69, 94.2%) in serum samples from patients with GC. Levels of MIA were raised in a small proportion of serum samples from patients with GC (4/69, 5.8%). In Boyden chamber invasion assays, MIA-transfected GC cells were up to three times more invasive than cells transfected with empty vector. Taken together, these results suggest that MMP-10 is a good marker for the detection of GC and that MIA and MMP-10 are prognostic factors for GC. As expression of MIA and MMP-10 is narrowly restricted in cancer, these two molecules may be good therapeutic targets for GC. Oncogene (2006) 25, 2546–2557. doi:10.1038/sj.onc.1209279; published online 5 December 2005 Keywords: gastric cancer; MIA; MMP10; DKK4; SAGE; tumor serum marker Introduction According to the World Health Organization, gastric cancer (GC) is the fourth most common malignancy worldwide, with approximately 870000 new cases occurring yearly. Mortality due to GC is second only to that due to lung cancer (Ohgaki and Matsukura, 2003). Cancer develops as a result of multiple genetic and epigenetic alterations (Yasui et al., 2000; Ushijima and Sasako, 2004). Better knowledge of changes in gene expression that occur during gastric carcinogenesis may lead to improvements in diagnosis, treatment, and prevention. Identification of novel biomarkers for cancer diagnosis and novel targets for treatment is a major goal in this field (Yasui et al., 2004). Genes encoding transmembrane/secretory proteins expressed specifically in cancers may be ideal biomarkers for cancer diagnosis (Buckhaults et al., 2001). If the function of the gene product is involved in the neoplastic process, this gene may constitute a therapeutic target. We previously performed serial analysis of gene expression (SAGE) on four primary GC samples (Gene Expression Omnibus accession number GSE 545; SAGE Hiroshima GC tissue) and identified several genes and tags that are potentially involved in invasion, metastasis, and carcinogenesis (Oue et al., 2004; Yasui et al., 2004). In this study, to identify potential molecular markers for diagnosis of GC and molecular therapeutic targets, we systematically searched for GC-specific genes in SAGE libraries. Comparing GC SAGE libraries with those of various normal tissues in the SAGEmap Received 28 June 2005; revised 12 September 2005; accepted 25 October 2005; published online 5 December 2005 Correspondence: Dr W Yasui, Department of Molecular Pathology, Hiroshima University Graduate School of Biomedical Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan. E-mail: wyasui@hiroshima-u.ac.jp Oncogene (2006) 25, 2546–2557 & 2006 Nature Publishing Group All rights reserved 0950-9232/06 $30.00 www.nature.com/onc ONCOGENOMICS