Estrogen mitogenic action. I. Demonstration of estrogen-dependent MTW9/PL2 carcinogen-induced rat mammary tumor cell growth in serum-supplemented culture and technical implications |
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Authors: | Jorge E Moreno-Cuevas David A Sirbasku |
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Institution: | (1) The University of Texas-Houston Health Science Center, P.O. Box. 20036, 77225-0036 Houston, Texas;(2) Department of Biochemistry and Molecular Biology, The University of Texas Medical School, 6431 Fannin Street, 77030 Houston, Texas |
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Abstract: | Summary The MTW9/PL cell line was established by our laboratory in culture from the carcinogen-induced hormone-responsive MT-W9A rat
mammary tumor of a Wistar-Furth (W/Fu) rat. This tumor formed estrogen, androgen, and progesterone responsive tumors in W/Fu
rats (Sirbasku, D. A., Cancer Res. 38:1154–1165; 1978). It was later used to derive the MTW9/PL2 cell population which was
also estrogen-responsive in vivo (Danielpour, D., et al., In Vitro Cell. Dev. Biol. 24∶42–52; 1988). In the study presented
here, we describe serum-supplemented culture conditions in which the MTW9/PL2 cells demonstrate≥80-fold steroid hormone growth
responses. All sera used were steroid hormone-depleted by charcoal-dextran treatment at 34°C. The studies were done with horse
serum as well as serum from other mammalian species. The growth of the MTW9/PL2 cells was biphasic in response to hormone-depleted
serum. Concentrations of ≤5% (v/v) promoted optimum growth. Above this concentration, serum was inhibitory. Concentrations
≥40% (v/v) inhibited growth altogether. Addition of 1.0×10−13−1.0×10−8
M 17β-estradiol (E2) reversed the inhibition completely. At 1.0×10−8
M, estrone, estriol and diethylstilbestrol promoted growth as well as E2. Testosterone and dihydrotestosterone promoted growth only at ≥10−7
M. Progesterone was effective only at≥10−6
M. Cortisol was ineffective. Labeled-hormone-binding analysis and Western immunoblotting documented that MTW9/PL2 cells had
estrogen and progesterone receptors but not androgen or cortisol receptors. Estrogen treatment of MTW9/PL2 cells induced a
concentration and time dependent increase in progesterone receptors. We conclude (1) the MTW9/PL2 population is the first
highly steroid hormone-responsive rat mammary tumor cell line to be established in culture from a carcinogen-induced tumor,
and (2) sera from a number of species including horse, rat and human contain an inhibitor which mediates estrogen sensitive
MTW9/PL2 cell growth in culture. |
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Keywords: | carcinogen-induced rat mammary tumors estrogens androgens progesterone glucocorticoid steroid hormone receptors growth regulation serum inhibitor |
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