Gene expression profile of gastric carcinoma: Identification of genes and tags potentially involved in invasion, metastasis, and carcinogenesis by serial analysis of gene expression

Gastric carcinoma (GC) is one of the most common malignancies worldwide. To better understand the genetic basis of this disease, we performed serial analysis of gene expression (SAGE) on four primary GC samples and one associated lymph node metastasis. We obtained a total of 137,706 expressed tags (Gene Expression Omnibus accession number GSE 545, SAGE Hiroshima gastric cancer tissue), including 38,903 that were unique. Comparing tags from our GC libraries containing different stages and different histologies, we found several genes and tags that are potentially involved in invasion, metastasis, and carcinogenesis. Among these, we selected 27 genes and measured mRNA expression levels in an additional 46 GC samples by quantitative reverse transcription-PCR. Frequently overexpressed genes (tumor/normal ratio > 2) were COL1A1 (percentage of cases with overexpression, 78.3%), CDH17 (73.9%), APOC1 (67.4%), COL1A2 (58.7%), YF13H12 (52.2%), CEACAM6 (50.0%), APOE (50.0%), REGIV (47.8%), S100A11 (41.3%), and FUS (41.3%). Among these genes, mRNA expression levels of CDH17 and APOE were associated with depth of tumor invasion (P = 0.0060 and P = 0.0139, respectively), and those of FUS and APOE were associated with degree of lymph node metastasis (P = 0.0416 and P = 0.0006, respectively). In addition, mRNA expression levels of FUS, COL1A1, COL1A2, and APOE were associated with stage (P = 0.0414, P = 0.0156, P = 0.0395, and P = 0.0125, respectively). Quantitative reverse transcription-PCR analysis also showed a high level of REGIV expression (> 100 arbitrary units) in 14 of 46 GC samples (30.4%) but not in noncancerous tissues. We detected V5-tagged RegIV protein in the culture media of cells transfected with pcDNA-RegIV-V5 by Western blot. Our results provide a list of candidate genes that are potentially involved in invasion, metastasis, and carcinogenesis of GC. REGIV may serve as a specific biomarker for GC.