Abstract: BACKGROUND ＆ AIM：The fluorescent differential display technique was used to clone differentially- expressed genes in gastric cancer, its premalignant lesions and normal gastric tissue. This might be helpful to understand the molecular mechanisms of tumor formation, early diagnosis and treatment of gastric cancer. MATERIAL AND METHODS: The differentially-expressed cDNA bands were isolated and identified by fluorescent differential display in 3 gastric cancers,3 matched normal gastric mucosa, 3 premalignant lesions These were then recovered, amplified, cloned and sequenced. The ribosomal protein S24 (RPS24) gene was one of the up-regulated genes and was confirmed by Northern hybridization. RPS24 gene expression in different tissue was analyzed in serial analysis of gene expression(SAGE)and UniGene databases. RESULTS: A differentially-expressed cDNA fragment was expressed highly in gastric cancers, This cDNA fragment was homologous to RPS24 gene and Northern hybridization confirmed the differential expression. RPS24 was highly expressed and extensively distributed in various tumor tissues. CONCLUSION: RPS24 gene expression was significantly higher in gastric cancer, and could be correlated with gastric cancer development.

Key words: gastric cancer, mRNA differential display, ribosomal protein S24 gene, Northern hybridization