Growth Regulation of Cultured Human Pituitary Cells by Steroidal and Nonsteroidal Compounds in Defined Medium

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Abstract
Human pituitary tumor tissue has been used to derive a cell line from which a subline (18–54SF) has been continuously propagated for over 50 passages in serum-free medium without supplements. These cells grow with a generation time of 30–40 h in serum-free medium and excrete two functional products, a growth factor and PRL, into the conditioned medium. We have also found that the growth of 18–54SF cells may be inhibited by specific additions of steroidal and nonsteroidal compounds. The steroids progesterone, 17β-estradiol, and estrone inhibit 18–54,SF cell growth approximately 75% at concentrations of 3.2 × 10-6, 1.8 × 10-6, and 3 × 10-6M, respectively. Other progestin metabolites do not have any effect on growth at concentrations up to 1.7 × 10-5M. The nonsteroidal progestin analogs 17α-hydroxy-6α-methyl-A4-pregnen-3,20-dione, norethynodrel (17α-ethynyl-17beta;-hydroxy-5(10)-estren-3-one) and norethindrone (17-hydroxy-19-nor-17α-pregn-4-en-20yn-3-one) inhibited cell growth as well as or better than progesterone. Norethindrone was the most effective nonsteroidal progestin tested, inhibiting cell growth about 90% at addition of concentrations of 1.6 × 10-6M to serum-free medium. The nonsteroidal estrogen diethylstilbestrol inhibited 18–54,SF cell growth about 75% after 10 days of incubation at 1.85 × 10-7M in serum-free medium. Another nonsteroidal estrogen, ethynyl estradiol, was much less effective than diethylstilbestrol. None of the androgens tested affected the growth of these cells. The antiestrogens clomiphene citrate and MER-25 were also investigated. Clomiphene citrate and ethamoxytriphetol (MER-25) inhibited 18-54,SF cell growth about 50% at concentrations of 2-3 × 10-8 and 2–3 × 10-8M, respectively. At concentrations of 2 × 10-7 and 10-6 M or higher, clomiphene citrate and MER-25, respectively, caused extensive cell detachment from the dishes within 3–4 days and eventual cell death. The 18–54SF cultured human pituitary cell system should prove to be useful for analyzing specific factors that may affect the growth of human pituitary tumors.