ヒト胃癌のヌードマウスにおける癌性腹膜炎モデルの確立とMitomycin Cによる腫瘍細胞増殖促進効果について

Abstract

Malignant potential of carcinoembryonic antigen (CEA)-producing human gastric adenocarcinoma (NS-8) was studied by intraperitoneal transplantation in nude mice. NS-8 carcinomatous peritonitis model was established by intraperitoneal transplantation of more than 1×10⁵ tumor cells. Pretreatment of MMC (5 mg/kg or 1 mg/kg) in the peritoneal cavity 3 hours before i. p. inoculation of 1×10⁶ tumor cells resulted in enhancement of the malignant potential and increase of plasma CEA level. Posttreatment of MMC in the peritoneal cavity 3 hours after i. p. inoculation of 1×10⁶ tumor cells reduced tumor growth and plasma CEA level. A slight enhancement of the malignant potential was recognized by pretreament of MMC in the peritoneal cavity 3 hours before i. p. inoculation of 1×10⁴ tumor cells. Peritoneal exudate cells (PEC) were decreased by MMC (5 mg/kg) i. p. injection at 3 days. Macrophages of PEC were decreased about 30% by MMC i. p. injection at 3 hours. The peritoneal surface was observed after MMC treatment by scanning electron microscopy (SEM). Microvilli of the peritoneal surface were injured from 24 hours after MMC i. p. injection. These results suggest that immunological supression in the peritoneal cavity and peritoneal surface tissue injury caused by pretreatment of MMC may play an important role in malignant potential.