Intraperitoneal delivery of a small interfering RNA targetingNEDD1prolongs the survival of scirrhous gastric cancer model mice

The prognosis of patients with advanced diffuse‐type gastric cancer (GC), especially scirrhous gastric cancer (SGC) remains extremely poor. Peritoneal carcinomatosis is a frequent form of metastasis of SGC. With survival rates of patients with peritoneal metastasis at 3 and 5 years being only 9.8% and 0%, respectively, development of a new treatment is urgently crucial. For such development, the establishment of a therapeutic mouse model is required. Among the 11 GC cell lines we examined, HSC‐60 showed the most well‐preserved expression profiles of the Hedgehog and epithelial‐mesenchymal transition pathways found in primary SGCs. After six cycles of harvest of ascitic tumor cells and their orthotopic inoculation in scid mice, a highly metastatic subclone of HSC‐60, 60As6 was obtained, by means of which we successfully developed peritoneal metastasis model mice. The mice treated with small interfering (si) RNA targeting NEDD1, which encodes a gamma‐tubulin ring complex‐binding protein, by the atelocollagen‐mediated delivery system showed a significantly prolonged survival. Our mouse model could thus be useful for the development of a new therapeutic modality. Intraperitoneal administration of siRNAs of targeted genes such as NEDD1 could provide a new opportunity in the treatment of the peritoneal metastasis of SGC.