LUPRON RETARDS PROLIFERATION OF OVARIAN EPITHELIAL TUMOR-CELLS CULTURED IN SERUM-FREE MEDIUM

Some patients with recurrent ovarian epithelial cancer respond favorably to treatment with GnRH agonists. This effect was proposed to be mediated by suppression of pituitary gonadotropin release. The present in vitro study investigated effects of human gonadotropin (Pergonal LH/FSH, 1:1) and Lupron, a GnRH agonist, on proliferation of an ovarian cancer cell line, 2774, which is estrogen receptor negative and grows well in serum-free, defined medium. Pergonal, 10 IU/mL or 30 IU/mL, did not enhance cell proliferation, which argues against stabilization of ovarian tumors in vivo due to decreased serum gonadotropin. Lupron, 1.4-mu-g/mL and 140-mu-g/mL, retarded cell division by day 6-8 of culture, in a dose-dependent manner. Flow cytometric cell cycle phase DNA analysis demonstrated Lupron caused a reversible 5-6% increase in the portion of cells in rest phase, G0/G1, compared to controls during log growth, and a corresponding decrease in the portion of cells in DNA synthesis, S phase. However, long-term culture, 3 weeks, with Lupron failed to arrest cells in G0/G1, and experimental cultures plateaued at cell number similar to control cultures. We conclude Lupron's effect on ovarian cancer cell proliferation is independent of gonadotropin and steroid, involves a cell cycle regulatory event, and duration of benefit observed in vivo for some patients may be related to total tumor volume at the time of treatment.