[Antitumor activity and cell cycle effects of delta 12-PGJ2 in vivo]

To assess antitumor activity and the cell cycle effects of delta 12-PGJ2 in vivo, delta 12-PGJ2 was injected intraperitonealLy into nude mice into which human colon carcinoma (COLO 320 DM) had been transplanted. Antitumor activity was assessed on the basis of tumor doubling time and tumor growth inhibition rate. No antitumor activity could be found in groups administered 10 mg/kg or 20 mg/kg of delta 12-PGJ2 (10 mg/kg group, 20 mg/kg group). But the doubling time of the 30 mg/kg group was significantly longer than that of the control group (p less than 0.01), and the tumor growth inhibition rate of this group was 35.3%. Analysis of the cell cycle effects by mitotic index and immunohistochemical methods (BrdU labeling index, Ki-67 positive cells rate) indicated no difference in the growth fractions of the control and 30 mg/kg groups. But in the 30 mg/kg group, the S-phase and M-phase populations in the cell cycle decreased. Cell progression was thus considered to possibly be blocked in the G1-phase. No effects of delta 12-PGJ2 could be detected on mice weight and the histological appearance of the liver and kidney. delta 12-PGJ2 thus appears to qualify as an antitumor agent of gastrointestinal carcinomas.