Abstract: To investigate the expression and biological significance of Ras protein activator like-1 gene (RASAL1) in normal human gastric epithelial cell line and different differentiated gastric cancer cell lines. METHODS: The expressions of RASAL1 mRNA and protein were respectively detected by PT-PCR and Western blot in three kinds of gastric cancer cell lines, including well differentiated MKN-28, moderately differentiated SGC-7901, poorly differentiated BGC-823, and normal gastric epithelial cell line GES-l. The mutation of K-Ras gene codon 12 was detected by PCR and gene sequencing. RESULTS: The results of PT-PCR and Western blot showed that both of the expressions of RASAL1 mRNA and proteins were decreased in all three gastric cancer cell lines as compared with the normal gastric epithelial cell line GES-l. It’s expression level was correlated with the differentiation: the poorest differentiation the lowest expression. The mutation of K-Ras gene codon 12 was not found in any of the gastric cancer cell lines. CONCLUSION: RASAL1 expression was reduced in the gastric cancer cell line that contain wild type K-Ras gene, and its expression level may be correlated with the degree of differentiation.

Key words: Ras potein activator like-1, gastric cancer cell lines, gene expression, point mutation