Growth-stimulating effect of pharmacological doses of glucocorticoid on androgen-responsive Shionogi carcinoma 115 in vivo in mice and in cell culture.

It has been generally accepted for 20 years that the growth of Shionogi carcinoma 115 (SC115) is stimulated only by androgen. However, we recently found that the growth of SC115 cells is also stimulated by pharmacological doses of estrogen in vivo but not in cell culture. In the present study, the growth-stimulatory effect of glucocorticoid on SC115 cells was examined. In castrated mice, daily injections of high doses of dexamethasone (100 micrograms/mouse) markedly stimulated the tumor growth, and the growth approached that found in normal males. However, daily injections of physiological doses of dexamethasone (4 micrograms/mouse) or high doses of epitestosterone, progesterone, or cholesterol (200-5000 micrograms/mouse) did not enhance the tumor growth in castrated mice. The androgen dependency, growth speed, steroid receptors, and histological type of the tumors grown by pharmacological doses of glucocorticoid were not significantly different from those of the original SC115 tumors grown by androgen. In a serum-free medium [Ham's F-12:Eagle's minimum essential medium (1:1, v/v) containing 0.1% bovine serum albumin], the proliferation of SC-3 cells (a cloned cell line from SC115 cells) was markedly (by up to 25-fold) stimulated by 10(-10)-10(-8) M testosterone, whereas the proliferation was only slightly but significantly (by up to 3.3-fold) stimulated by 10(-8)-10(-5) M dexamethasone. The present findings demonstrate that the growth of SC115 cells in vivo and in cell culture is significantly stimulated by physiological doses of androgen or pharmacological doses of glucocorticoid.

Difference in extractability of estradiol- and tamoxifen-receptor complex in the nuclei from MCF-7 cells with Nonidet P-40.

The extraction of [3H]estradiol- and [3H]tamoxifen-receptor complex in the nuclei from MCF-7 cells with the nonionic detergent Nonidet P-40 has been studied. We found that there is a striking difference in the extractability of estradiol- and tamoxifen-receptor complex from nuclei with 0.5% Nonidet P-40. The nuclear bound estradiol-receptor complex is scarcely extractable with Nonidet P-40. In contrast, almost all of the nuclear bound tamoxifen-receptor complex is extractable. The nuclear [3H]tamoxifen-receptor complex extracted in the presence of Nonidet P-40 sediments in two peaks at 7 S and 5 S. The latter sedimentation rate is the same with that of the nuclear [3H]tamoxifen-receptor complex extracted with 0.4 M KCl. The nuclear [3H]estradiol-receptor complex extracted with 0.4 M KCl sediments at 4 S. The results suggest that interaction of tamoxifen-receptor complex with chromatin is different from that of estradiol-receptor complex.

Effects of thiocyanate on cytosol androgen receptor from Shionogi carcinoma 115.

The effects of KSCN and other chaotropic salts on the androgen receptor in cytosol of Shionogi carcinoma 115 were studied by means of charcoal adsorption assay and sucrose gradient centrifugation. When KSCN or NaSCN was added to the [3H]-dihydrotestosterone-cytosol mixture at the final concentration of 0.5 M, the androgen binding to the cytosol receptor was considerably inhibited. The inhibition reached maximum within 5 h at 0 degrees C and was dependent on the kind of chaotropic anion added: the potency of inhibitory effect in descending order was KSCN greater than KI greater than KBr greater than KCl. The inhibition was not observed in the estradiol-receptor interaction with KSCN or NaSCN up to 0.5 M. When 0.5 M KSCN-treated androgen-cytosol mixture was subjected to gel filtration or (NH4)2SO4 fractionation to remove the salt, a partial recovery (30-40%) in specific binding activity was observed. The binding activity of androgen receptor was unaffected by a treatment with KSCN up to 0.1 M and the androgen-receptor complex sedimented in a 5S form in 0.1-0.3 M KSCN, 0.5 M KCl or 0.5 M KBr. These results suggest that the binding activity of androgen receptor is more susceptible than that of estrogen receptor to chaotropic salts which cause impairment in intramolecular hydrophobic interactions.

Apparent ineffectiveness of adriamycin for growth of androgen-dependent Shionogi carcinoma 115 in the mouse.

Although adriamycin (1 mg/kg) and 5-fluorouracil (25 mg/kg) were equally effective in inhibiting the growth of Ehrlich carcinoma, both ascites and solid forms, in the mouse, the growth of Shionogi carcinoma 115 in the male DS mouse was relatively resistant to the treatment with adriamycin as compared to 5-fluorouracil. However, direct cytotoxic activity of adriamycin in cultured Shionogi carcinoma 115 (SC 115) cells was about 1000-fold molar potent when compared with 5-fluorouracil. The apparent ineffectiveness of adriamycin against SC 115 in the DS mouse seems to be, at least in part, due to the depression of host defence mechanisms.

Stimulatory effects of dexamethasone and indomethacin on growth of androgen-dependent Shionogi carcinoma 115 in the mouse.

The effects of dexamethasone and indomethacin on the growth of androgen-dependent Shionogi carcinoma 115 were studied. When castrated male DS mice were treated with dexamethasone for 2 weeks at daily doses of 1-5 mg/kg starting from 3 days before tumor inoculation, the tumor weight as well as the transplantability was significantly increased. The tumor grown in dexamethasone-treated mice had morphological, biochemical and biological characteristics similar to those of the original Shionogi carcinoma 115. Indomethacin at daily doses of 2-10 mg/kg also stimulated the tumor growth in castrated DS mice, but the effect was less pronounced than that of dexamethasone. In allogeneic male ICR mice, dexamethasone promoted tumor growth, but indomethacin had no effect. These results suggest that tumor growth in the mouse is stimulated not only by androgens but also by glucocorticoids through the suppression of immune responses of the host and direct action on the tumor cells.

Salt extractability of nuclear receptor-estrogen complex from the rat uterus.

Estrogen receptors in the nuclei of rat uterus were determined 1 or 6 h after the injection of [3H]estradiol. Ratio of 0.4 M KCl-extractable to -resistant receptor-estradiol complex was constant during this time interval. Three consecutive extractions took out about 95% of receptor-estradiol complex either 1 or 6 h after injection. Extraction with KCl before the exchange assay reduced the amount of salt-resistant nuclear receptor-estradiol complex. However, when exchange incubation with [3H] estradiol was done before KCl extraction, salt-resistant receptor-estradiol complex was significantly increased, even after three consecutive extractions.

Effects of estrogens and antiestrogens on androgen-dependent growth of Shionogi carcinoma 115: role of estrogen receptor.

Experiments were performed to observe the role of estrogen receptor in the proliferation of androgen-dependent mouse tumor, Shionogi carcinoma 115. Estradiol and diethylstilbestrol inhibited tumor growth as well as the weight gain of seminal vesicles and prostate glands in intact male mice. Tamoxifen decreased the tumor weight in intact males. Both nitromifene given to intact mice and tamoxifen given to castrated androgenized mice decreased the weight of seminal vesicles, but increased tumor weight. Estradiol was bound to the androgen receptor of the tumor cytosol with relatively high affinity, whereas diethylstilbestrol, tamoxifen and nitromifene were not. These were effective competitors in the estrogen receptor present in the tumor cytosol. These results suggest that the estrogen receptor system in Shionogi carcinoma 115 inhibits the proliferation of tumor cells.

Dexamethasone suppressibility of plasma pregnenolone or dehydroepiandrosterone in gonadectomized patients.

The 9 AM dexamethasone suppression test was carried out in gonadectomized patients, and plasma pregnenolone or dehydroepiandrosterone (DHA) was radioimmunoassayed following various amounts of dexamethasone administration. Pregnenolone, as well as the plasma ACTH level, was completely suppressed with 1 mg dexamethasone, whereas 4 mg or 8 mg of dexamethasone was needed to induce a complete DHA suppression. These findings suggest that the gonads alone contribute to the poor dexamethasone suppressibility of pregnenolone in normal subjects, and that adrenal DHA secretion might be also regulated by an unidentified factor other than ACTH, which would be suppressed with large doses of dexamethasone.