ICAM-2 gene therapy for peritoneal dissemination of scirrhous gastric carcinoma.

PURPOSE Human scirrhous gastric carcinoma develops peritoneal dissemination with high frequency, and the prognosis of patients with peritoneal metastasis is poor. There have been few reports of an immunogene therapy for peritoneal dissemination. Intercellular adhesion molecule (ICAM)-2 is a second ligand of leukocyte function-associated antigen-1, which functions as a costimulatory molecule for effector cells. In the present study, we examined whether ICAM-2 transfection using adenovirus vector is effective gene therapy for peritoneal metastasis of gastric cancer. EXPERIMENTAL DESIGN We constructed an adenovirus vector, AdICAM-2, that encodes the full-length human ICAM-2 gene under control of the cytomegalovirus promoter. This vector expresses high levels of ICAM-2 on the human gastric cancer cell line OCUM-2MD3, which has high peritoneal metastatic ability in nude mice. We investigated the antitumor effects of gene transfer of ICAM-2 using the adenovirus vector AdICAM-2 in vitro and in vivo. RESULTS ICAM-2 expressed on OCUM-2MD3 cells by AdICAM-2 demonstrated significantly high adhesiveness to and cytotoxicity against peripheral blood mononuclear cells in vitro compared with the control adenovirus vector AdlacZ. Intratumoral injection of AdICAM-2 significantly inhibited the growth of s.c. tumor. Mice with peritoneal metastasis survived for a significantly longer time after AdICAM-2 injection, compared with injection of AdlacZ. Histopathological findings revealed that many natural killer cells infiltrated the peritoneal metastatic lesions after AdICAM-2 injection. CONCLUSIONS These findings suggest that transduction of ICAM-2 into cancer cells enhances the adhesion and activation of natural killer cells, resulting in a reduction of peritoneal metastasis. ICAM-2 transfection using adenovirus vector might be an effective form of gene therapy for peritoneal metastasis of gastric cancer.