Adjuvant effects of prostaglandin D2 to cisplatin on human ovarian cancer cell growth in nude mice.

Adjuvant effects of prostaglandin D2 to cisplatin on tumor growth were studied by using nude mice bearing HR cells derived from human ovarian carcinoma. Combinations of 0.2 or 0.4 microgram/ml cisplatin and 0.05 or 0.1 microgram/ml prostaglandin D2, which did not affect the HR cell proliferation alone, resulted in a significant inhibition of cell proliferation. In addition, tumor take of HR cells by nude mice in groups treated with a combination of cisplatin and prostaglandin D2 was inhibited. Although there was no significant difference between tumor volumes in mice treated with prostaglandin D2 alone or cisplatin alone and untreated mice, when cisplatin was administered with 1 mg/kg prostaglandin D2 the tumor volume was significantly smaller on days 21 and 35, compared to that of untreated mice. When cisplatin and 2 or 4 mg/kg prostaglandin D2 were combined, the tumor growth was significantly inhibited after day 21, compared not only to that of untreated mice but also of mice treated with cisplatin alone or prostaglandin D2 alone. Such a combination therapy by cisplatin and prostaglandin D2 seemed to result in prevention by prostaglandin D2 of immunological suppression which may be induced by cisplatin. Thus, such a combination therapy brought about a significant prolongation to the survival time.