RESUMEN
BACKGROUND: Gastric cancer (GC) is the fifth commonest malignancy worldwide and still one of the leading causes of cancer-related death. The aim of this study was to identify a novel prognostic marker or therapeutic target for GC. METHODS: We analyzed candidate genes from our previous Escherichia coli ampicillin secretion trap (CAST) libraries in detail, and focused on the FKTN gene because it was overexpressed in both GC cell line CAST libraries, MKN-1 and MKN-45. RESULTS: Quantitative reverse transcriptase PCR analysis of FKTN revealed that FKTN messenger RNA was overexpressed in nine of 28 (32.1 %) GC tissue samples compared with nonneoplastic gastric mucosa. Immunostaining of fukutin showed that 297 of 695 cases (42.7 %) were positive for fukutin. Fukutin-positive GC cases were significantly associated with differentiated histological features, and advanced T grade and N grade. In addition, fukutin expression was observed more frequently in the intestinal phenotype (51 %) of GC than in other phenotypes (37 %) when defined by the expression patterns of mucin 5AC, mucin 6, mucin 2, and CD10. FKTN small interfering RNA treatment decreased GC cell proliferation. CONCLUSIONS: These results indicate that the expression of fukutin may be a key regulator for progression of GC with the intestinal mucin phenotype.