RESUMEN
<p><b>OBJECTIVE</b>To clone and identify gastric cancer-related genes and explore the possible pathogenic mechanism of gastric cancer.</p><p><b>METHODS</b>The differentially expressed cDNA bands were isolated by fluorescent mRNA differential display in gastric cancer specimens, matched normal gastric mucosa and premalignant lesions. The motility-related protein-1 (MRP-1/CD9) gene was one of the down-regulated genes. MRP-1/CD9 gene expression in different kinds of gastric tissue was analyzed by Northern blot and reverse transcription-polymerase chain reaction (RT-PCR).</p><p><b>RESULTS</b>MRP-1/CD9 expression was down-regulated in all gastric cancer tissues. Northern blot analysis confirmed this differential expression. RT-PCR analysis showed that the MRP-1/CD9 gene expression was much lower in gastric cancers(0.31+/-0.18) than in the matched normal gastric tissue (0.49+/-0.24) and in the premalignant lesions (0.47+/-0.18) (P<0.05), and its expression in intestinal type gastric cancer (0.38+/-0.16) was higher than that in diffuse type gastric cancer (0.22+/-0.17) (P<0.05).</p><p><b>CONCLUSION</b>The MRP-1/CD9 gene expression was down-regulated in gastric cancer, its expression was probably related to the carcinogenesis and histology types of gastric cancer.</p>