[Antineoplastic effect of prostaglandins on human glioma in athymic nude mice]

The prostaglandins (PG) are known to have various physiological effects. Some series of prostaglandins such as PG D2 have been reported to inhibit growth of tumor cells. In this study, the growth-inhibitory effects of PG A2, PG D2, PG J2 and 6-keto PGE1 were investigated in nude mice receiving subcutaneous transplant of human brain tumor. One to two milligram of prostaglandins was given intraperitoneally every day for three weeks. Tumor volumes were measured twice weekly and the tumor reduction rates (treated/control) were evaluated. T/C rate treated with PG D2 or PG A2 was 50-60% respectively. The effectiveness of PG J2 or 6-keto PGE1 was inferior to that of PG A2 or PG D2. But in the evaluation of antitumor effects of PG J2, we must consider the fact that the activity of PG J2, is liable to be lost. The effect of PG D2 on proliferation of cultured glioma cells was also studied. At concentrations of 10 micrograms/ml, PG D2 strongly inhibited the proliferation of glioma cells. However, precise mechanism of prostaglandin action is presently unknown. Further studies are required to clarify the mechanism of antitumor effects of prostaglandins.