Characterization of Systemic Disease Development and Paw Inflammation in a Susceptible Mouse Model of Mayaro Virus Infection and Validation Using X-ray Synchrotron Microtomography.

Mayaro virus (MAYV) is an emerging arthropod-borne virus endemic in Latin America and the causative agent of arthritogenic febrile disease. Mayaro fever is poorly understood; thus, we established an in vivo model of infection in susceptible type-I interferon receptor-deficient mice (IFNAR-/-) to characterize the disease. MAYV inoculations in the hind paws of IFNAR-/- mice result in visible paw inflammation, evolve into a disseminated infection and involve the activation of immune responses and inflammation. The histological analysis of inflamed paws indicated edema at the dermis and between muscle fibers and ligaments. Paw edema affected multiple tissues and was associated with MAYV replication, the local production of CXCL1 and the recruitment of granulocytes and mononuclear leukocytes to muscle. We developed a semi-automated X-ray microtomography method to visualize both soft tissue and bone, allowing for the quantification of MAYV-induced paw edema in 3D with a voxel size of 69 µm3. The results confirmed early edema onset and spreading through multiple tissues in inoculated paws. In conclusion, we detailed features of MAYV-induced systemic disease and the manifestation of paw edema in a mouse model extensively used to study infection with alphaviruses. The participation of lymphocytes and neutrophils and expression of CXCL1 are key features in both systemic and local manifestations of MAYV disease.

Methamphetamine, smoking, and gestational hypertension affect norepinephrine levels in umbilical cord tissues.

BACKGROUND: These studies were undertaken to determine methamphetamine (METH) and smoking effects on umbilical vascular dynamics and pregnancy outcomes. MATERIALS AND METHODS: Umbilical cords (54) were collected prospectively at birth, washed of blood, and stored at -80°C. Cords were thawed and lysates prepared, then catecholamine levels quantified with enzyme-linked immunosorbent assay (ELISA). RESULTS: Catecholamine levels in umbilical cords were not associated with maternal or gestational age, gravidity, parity, neonatal or placental weight. Neither smoking nor METH affected dopamine or epinephrine. However, smoking (two-fold) and METH (four-fold) decreased norepinephrine and together a 60-fold reduction occurred (p = 0.025). Cesarean section and hypertension were both associated with lower norepinephrine levels (p < 0.001) regardless of drug status. In normotensive pregnancies, smoking and METH significantly decreased norepinephrine levels (two-fold and 3.5-fold each, respectively) with a 40-fold decrease for METH/smoking together. DISCUSSION: Depletion of norephinephrine by METH and smoking likely contributes to pregnancy complications, including the higher incidence of respiratory distress and postpartum hemorrhage in cesarean section.

The spin temperature of NH3 in Comet C/1999S4 (LINEAR).

A high-dispersion spectrum of Comet C/1999S4 (LINEAR) was obtained in the optical region with the high-dispersion spectrograph on the Subaru telescope when the comet was 0.863 astronomical units from the Sun before its disintegration. We obtained high signal-to-noise ratio emission lines of the cometary NH2 bands from which an ortho-to-para ratio (OPR) of 3.33 +/- 0.07 was derived on the basis of a fluorescence excitation model. Assuming that cometary NH2 mainly originates from ammonia through photodissociation, the derived OPR of NH2 molecules should reflect that of ammonia, which provides information on the environment of molecular formation or condensation and of the thermal history of cometary ices. Assuming that the OPR of ammonia in comets was unchanged in the nucleus, the derived spin temperature of ammonia (28 +/- 2 kelvin) suggests that a formation region of the cometary ammonia ice was between the orbit of Saturn and that of Uranus in the solar nebula.

Electron spin resonance studies of erythrocytes from patients with Duchenne muscular dystrophy.

The membrane organization of the erythrocytes from patients with Duchenne muscular dystrophy was studied by means of electron spin resonance. The fluidity of the membrane near the polar region of Duchenne muscular dystrophy erythrocytes was similar to that of normal erythrocytes. The membrane environment in the nonpolar region, however, was quite different from that of normal erythrocytes, judged by the spectra with 2-(14-carboxytetradecyl) - 2 - ethyl - 4,4 - dimethyl - 3 - oxazolidinyloxyl as probe. The temperature dependence of the ratio of the line height of central field to that at the low field showed two inflection points in normal erythrocytes at pH 7.4 (13.5 degrees -16.5 degrees and 37.5 degrees -40.5 degrees C, respectively) but the inflection point in the lower temperature range was not detected in Duchenne muscular dystrophy erythrocytes. When pH was varied, an abrupt decrease in the ratio was observed at pH 5.9-5.6 in normal erythrocytes whereas there was a gradual decrease over the range of pH from 6.6 to 5.0 in Duchenne muscular dystrophy erythrocytes. The rate of reduction of the radical 2-(3-carboxypropyl)-4,4-dimethyl-2-tridecyl-3-oxazolidinyloxyl by ascorbate in normal erythrocytes was faster than that in Duchenne muscular dystrophy erythrocytes. Treatment of both erythrocytes with phloretin markedly reduced the rate of reduction by ascorbate and eliminated the difference in the two types of erythrocyte. These results indicate that in Duchenne muscular dystrophy the erythrocyte membrane is involved as well as the muscle cell.

Hypoxia-activated apoptosis of cardiac myocytes requires reoxygenation or a pH shift and is independent of p53.

Ischemia and reperfusion activate cardiac myocyte apoptosis, which may be an important feature in the progression of ischemic heart disease. The relative contributions of ischemia and reperfusion to apoptotic signal transduction have not been established. We report here that severe chronic hypoxia alone does not cause apoptosis of cardiac myocytes in culture. When rapidly contracting cardiac myocytes were exposed to chronic hypoxia, apoptosis occurred only when there was a decrease in extracellular pH ([pH](o)). Apoptosis did not occur when [pH](o) was neutralized. Addition of acidic medium from hypoxic cultures or exogenous lactic acid stimulated apoptosis in aerobic myocytes. Hypoxia-acidosis-mediated cell death was independent of p53: equivalent apoptosis occurred in cardiac myocytes isolated from wild-type and p53 knockout mice, and hypoxia caused no detectable change in p53 abundance or p53-dependent transcription. Reoxygenation of hypoxic cardiac myocytes induced apoptosis in 25-30% of the cells and was also independent of p53 by the same criteria. Finally, equivalent levels of apoptosis, as demonstrated by DNA fragmentation, were induced by ischemia-reperfusion, but not by ischemia alone, of Langendorff-perfused hearts from wild-type and p53 knockout mice. We conclude that acidosis, reoxygenation, and reperfusion, but not hypoxia (or ischemia) alone, are strong stimuli for programmed cell death that is substantially independent of p53.

Effects of thyroid hormone on androgen- or basic fibroblast growth factor-induced proliferation of Shionogi carcinoma 115 mouse mammary carcinoma cells in serum-free culture.

DNA synthesis of SC-3 cells cloned from mouse mammary carcinoma (Shionogi carcinoma 115) was remarkably enhanced by androgen as well as basic fibroblast growth factor (bFGF) at the early phase (days 1-3) of stimulation in serum-free culture condition. However, bFGF-induced DNA synthesis could not be observed at the late phase (days 4-6) of stimulation while androgen was able to continuously elicit DNA synthesis. When the effect of androgen on cell yield was examined, the cell number was increased while bFGF could not enhance cell growth. Androgen-induced heparin-binding growth factor partially purified from conditioned medium behaved like bFGF in terms of DNA synthesis and replication in SC-3 cells. SC-3 cells were found to contain the high-affinity binding site toward triiodothyronine. The dissociation constant and the maximum number of the binding sites were 7 x 10(-10) M and 1800/cell, respectively. Triiodothyronine significantly blunted the testosterone-induced DNA synthesis. On the other hand, bFGF-enhanced DNA synthesis was not substantially inhibited by triiodothyronine. These results suggest that androgen, but not bFGF, has unique action site(s) which might be important for SC-3 cell replication and might be antagonized by thyroid hormone.

Stimulative effects of estrogens on tumor growth and 5 alpha-steroid production in a mouse Leydig cell tumor line (T 124958-R).

The effects of estrogens on the growth and enzyme activities for androgen synthesis in a mouse Leydig cell tumor line (T 124958-R) were studied. The s.c. implantation of a diethylstilbestrol pellet resulted in a marked enhancement of the tumor growth. 5 alpha-Reductase activity (nmol/g/h) in tumors rapidly grown in the presence of diethylstilbestrol pellet was 4 times higher than that in tumors slowly grown in the absence of diethylstilbestrol, whereas an inverse relation was found for 17 beta-hydroxysteroid oxidoreductase activity. 17-Hydroxylase activities were similar in both tumors. The major C21- and C19-steroids formed from progesterone by the tumors grown in the presence of estrogen were 5 alpha-steroids such as 3 alpha- or 3 beta-hydroxy-5 alpha-pregnan-20-one, 3 alpha, 17-dihydroxy-5 alpha-pregnan-20-one, androsterone, and 5 alpha-androstane-3 alpha, 17 beta-diol, whereas the major steroids formed by the tumors in the absence of estrogen were 4-ene-3-ketosteroids such as 20 alpha-hydroxy-4-pregnen-3-one, 17-hydroxy-4-pregnene-3,20-dione, and testosterone. Furthermore, 10(-8) M of 17 beta-estradiol added in serum-free medium for 10 days significantly enhanced 5 alpha-reductase activities per 10(6) cells but significantly inhibited 17 beta-hydroxysteroid oxidoreductase activity in primary cell culture. These results indicate that estrogens stimulate the growth of T 124958-R in vivo and that estrogens may directly enhance 5 alpha-reductase activity but inhibit 17 beta-hydroxysteroid oxidoreductase activity in T 124958-R cells.

Biological characteristics and estrogen and progesterone receptors in mammary carcinoma induced in male Sprague-Dawley rats by a series of intragastric intubations of 7,12-dimethylbenz(a)anthracene.

Biological characteristics and estrogen (ER) and progesterone (PR) receptors were studied in male mammary carcinomas induced by 7,12-dimethylbenz(a)anthracene (DMBA) in male inbred Sprague-Dawley rats (MM). DMBA-induced carcinomas in females (MF) were used as controls. In 36 of 44 female rats given 20 mg DMBA once by gastric intubation at 50 days of age, MF with microscopic characteristics of cystic papillary adenocarcinoma developed 124 +/- 49 (S.D.) days after challenge. In all of the 42 male rats given 10 mg DMBA at 14-day intervals for 14 weeks starting from 28 days of age. MM with microscopic characteristics of medullary adenocarcinoma developed 106 +/- 21 days after the first intubation of DMBA. The growth of primary MM was unaffected by orchiectomy or estrogen. Eighty to 100% of the MM transplanted in the four groups could grow in intact female rats, ovariectomized female rats, intact male rats, and castrated male rats, while the transplanted MF could grow only in intact female rats. The histology of MM was unchanged in primary and transplanted tumors under various hormonal conditions. ER were present in almost all of the hormone-independent primary and transplanted MM, although the levels for cytosol ER in MM were significantly lower than those in MF. Injection of 10 micrograms 17 beta-estradiol induced marked synthesis of PR in primary and transplanted MM, even 24 and 48 hr after the 17 beta-estradiol injection. These findings show that MM are hormone independent but, like hormone-dependent female tumors, contain ER and estrogen-dependent PR.

Hyperlipidemia enhancement of renal preneoplasia but not tumor formation is due to elevated apoptosis in the Eker rat.

The influence of a high-fat diet on the appearance of renal tumors was assessed in the Eker rat model of hereditary renal carcinoma. Examination of H&E-stained sections showed a significant increase in the number of microscopic solid adenomas in the high-fat group compared with the low-fat group, whereas there was no significant difference in the number of macroscopic tumors between the two groups. Where had the tumor buds gone? Staining for apoptotic bodies occasionally revealed apoptosis in and around the microscopic adenomas. In addition, an Eker rat renal tumor-derived cell line showed apoptosis when it was cultured with high concentrations of native and acetylated low-density lipoprotein. These findings suggested that tumor buds repeatedly appeared and disappeared in Eker rats on a high-fat diet.

Partial characterization of protease(s) in human breast cancer cytosols that can degrade estrogen and progesterone receptors selectively.

Proteolytic activity in human breast cancer cytosols was studied using hormone receptors from rats as the substrates. Under the conditions tested, limited proteolysis of both the estrogen and the progesterone receptors in uterine cytosol was observed, but not proteolysis of the glucocorticoid or androgen receptors in liver or prostate cytosols, respectively. Although both the nonactivated and activated uterine estrogen receptors were attacked by the enzyme(s), molybdate-stabilized receptors were resistant to proteolysis. The product of estrogen receptor cleavage sedimented at approximately 4S in low-salt gradients and at 3 to 4S in high-salt gradients. This fragment retained both the steroid-binding and DNA-binding domains. The marked decrease in its DNA-binding ability, compared with the salt-dissociated but non-proteolyzed receptors, may be attributable to interactions of the fragment with dialyzable modulator(s) in cytosol. The proteolytic activity in tumor cytosol was leupeptin sensitive and was precipitated by (NH4)2SO4 at 30 to 60% saturation. Its sedimentation coefficient was 4 to 5S. The proteolytic activity was identified in 70% of estrogen receptor-negative tumors but in only 40% of estrogen receptor-positive tumors.

Growth-stimulative effect of estrogen on androgen-dependent Shionogi carcinoma 115.

The stimulative effect of 17 beta-estradiol on the growth of androgen-dependent Shionogi carcinoma 115 and estrogen receptor in the tumor were studied. The incorporation of 17 beta-[3H]estradiol following a single injection of 17 beta-[3H]estradiol into tumor-bearing animals was 5- to 20-fold higher in the tumor than in the spleen and blood. Scatchard plot analyses showed that the tumor cytosol possessed a 17 beta-estradiol-binding site having a high affinity for 17 beta-estradiol [Kd 1.1 +/- 0.1 nM (S.E.)]. Competition experiments demonstrated that the 17 beta-estradiol binding was specific only for estrogenic compounds. Using sedimentation coefficient obtained by high-salt sucrose gradient (4.0S) and Stokes radius obtained by gel chromatography on Sephadex G-200 (46 A), the molecular weight of 17 beta-estradiol-binding component in the tumor cytosol was estimated to be 76,400. In castrated DS mice, a slight but significant increase in growth of s.c. grafted tumors was found by daily s.c. injections of either 17 beta-estradiol or 10 micrograms per mouse of testosterone propionate. Growth of the tumor maintained by 10 micrograms of testosterone propionate was augmented markedly by the addition of 4 micrograms of 17 beta-estradiol, and the growth approached the level induced by 100 micrograms of testosterone propionate. Simultaneous injections of bromocryptine inhibited an increase in 17 beta-estradiol-induced prolactin secretion but had no effect on the 17 beta-estradiol-enhanced tumor growth. These results demonstrate for the first time the stimulative effect of estrogen on the growth of androgen-dependent Shionogi carcinoma 115. The tumor contains typical estrogen receptor, which might be able to transmit estrogen signal to tumor cell nuclei with regard to tumor growth.

Effects of tamoxifen on estrogen-induced enhancement or inhibition of tumor growth in mouse Leydig cell tumor lines.

In order to avoid the complex dual effects of estrogen and antiestrogen, the attempt was made to establish the tumor lines in which estrogens show either stimulatory or inhibitory property in terms of the tumor growth. The administration of estrogen to host mice bearing one of the mouse Leydig cell tumor lines, called T 124958-R, resulted in marked enhancement of the tumor growth even at pharmacological levels of estrogen. On the other hand, estrogenization of host mice almost completely inhibited the growth of the other tumor line (T 22137) without detectable stimulatory effects. The physiocochemical properties of the cytosol estrogen receptor in both sublines were found to be similar in relation to the affinity toward ligands, steroid specificity, sedimentation profile, and the dissociation rate kinetics. Using these tumor lines, the action mechanism of tamoxifen on the tumor growth was examined. Daily administration of this compound (30 micrograms/mouse) led to enhanced tumor growth in T 124958-R, while the growth of T 22137 was inhibited by the same procedure. In the combination experiments, tamoxifen was found to be unable to antagonize estrogen-induced enhancement or inhibition of the growth in these tumors. In addition, both tumors contained similar levels of the antiestrogen binding sites. These results suggest that tamoxifen modulated the tumor growth through its estrogenic potency.

Inhibition of murine transformed Leydig cell proliferation by leukotrienes in serum-free culture.

We have previously shown that estrogen-dependent growth enhancement of murine transformed Leydig cells (B-1 F) is mediated through inhibition of arachidonic acid metabolite formation. In the present study, the growth-inhibitory ability of leukotrienes (LTs) on B-1 F cells in serum-free culture was directly addressed. All peptidyl LTs (LTC4, LTD4, and LTE4) inhibited B-1 F cell growth in a dose-dependent manner and exhibited maximum inhibition of DNA synthesis (60-80%) compared with that of untreated cells in a range of 10(-9) to 10(-8) M. To examine the mechanism of this LT-dependent inhibition, binding studies of LTD4 toward plasma membrane were conducted. Specific binding sites for LTD4 were identified. Scatchard analyses indicated the presence of a single class of high-affinity sites (Kd = 0.9 +/- 0.2 nM; maximum binding sites, 61 +/- 18 fmol/mg protein). This binding of LTD4 to the high-affinity site was markedly inhibited by ICI 198615, a specific inhibitor for LTD4. These results would suggest that inhibitory effects of LTs, at least LTD4, are elicited as a receptor-mediated event. In addition, this LT-dependent growth inhibition could not be blocked by simultaneous exposure of cells to estrogen, whereas estrogen partially protected arachidonic acid-dependent growth inhibition. Furthermore, treatment of cells with estrogen resulted in marked suppression of 5-lipoxygenase activity. Collectively, the present data clearly show that LTs play an important role as intermediates in an autocrine loop for B-1 F cells to exhibit estrogen-dependent growth.

Effect of androgen on proliferation of estrogen-responsive transformed mouse Leydig cells in serum-free culture.

We examined the effects of steroid hormones on the proliferation of transformed mouse Leydig cells (B-1) in serum-free culture condition. Among hormones examined, androgen as well as estrogen enhanced the cell proliferation rate. Hormone binding studies revealed that B-1 cells contained both androgen and estrogen receptors. In addition, androgen-enhanced cell growth was inhibited by antiandrogen, but not by antiestrogen, while estrogen-stimulated cell growth was suppressed by antiestrogen. However, the simultaneous addition of androgen and estrogen did not show an additive effect. Dose-response study on androgen-dependent cell growth revealed that relatively high concentrations (10(-7)-10(-6) M) of dihydrotestosterone were required to obtain the maximum response. This was at least partly explained by the finding that B-1 cells could metabolize dihydrotestosterone into the less active steroids. Finally, B-1 cells were found to grow more rapidly in normal than in castrated male mice. These results clearly indicate that the proliferation of B-1 cells is stimulated by both androgen and estrogen, which utilize the different receptor systems.

Effect of retinoic acid on proliferation of estrogen-responsive transformed murine Leydig cells in serum-free culture.

B-1 F cells, one of the sublines established from mouse Leydig cell tumor, have been found to be maintained as an estrogen-responsive cell line under the serum-free culture conditions. Reported results that retinoids have action mechanisms similar to those of estrogen prompted us to examine the effect of retinoids on the proliferation of B-1 F cells. Stimulation of B-1 F cell growth by retinoic acid in a dose-dependent manner was observed, whereas retinoic acid did not promote but inhibited the proliferation of MCF-7 cells (estrogen- and retinoic acid receptor-positive human breast cancer cells). To elucidate the mechanism of retinoic acid-dependent cell growth, simultaneous treatment with retinoic acid and estradiol was carried out. The result did not show the additive effect on B-1 F cell growth. Hydroxytamoxifen, a potent antiestrogen, inhibited not only estradiol-dependent but also retinoic acid-dependent cell growth. However, retinoic acid failed to be associated with estrogen receptor, suggesting that retinoic acid induced enhancement of B-1 cell growth through its interaction with retinoic acid receptor. Northern blot analyses of polyadenylated RNA with complementary DNA probes for human retinoic acid receptor alpha, beta, and gamma revealed the presence of transcripts encoded by retinoic acid receptor alpha gene in B-1 F cells. These results would suggest that enhancement of the B-1 F cell growth is mediated through interaction of retinoic acid with retinoic acid receptor alpha. This stimulatory activity is inhibited by estrogen receptor complexed with hydroxytamoxifen.

Unsaturated fatty acids are required for continuous proliferation of transformed androgen-dependent cells by fibroblast growth factor family proteins.

Increase in dietary fat intake has been reported to be associated with progression of hormone-dependent cancers. To explore its mechanism, we examined the effects of fatty acids on the growth of androgen-dependent SC-3 cells cloned from mouse mammary cancer (Shionogi carcinoma 115). Their androgen-dependent growth was potentiated by linoleic acid in the defined medium. The effect of linoleic acid on fibroblast growth factor (FGF)-dependent growth was also addressed because androgen had been demonstrated to exert its mitogenic activity on SC-3 cells through an induction of the unique FGF family protein termed as androgen-induced growth factor. Exposure of SC-3 cells to basic FGF or androgen-induced growth factor exhibited only transient growth response. However, simultaneous addition of linoleic acid to the medium sustained the proliferation of FGF-stimulated, but not FGF-unstimulated, cells, although linoleic acid did not exert the significant effect on the process of S-phase entry of basic FGF-stimulated cells. Palmitoleic acid and oleic acid appeared to exert the actions similar to linoleic acid, while stearic acid was without any effect. Neither cyclooxygenase inhibitor nor 5-lipoxygenase inhibitor could block the growth-promoting ability of linoleic acid. Linoleic acid also enhanced their anchorage-independent growth in the presence of basic FGF. These results indicate that these unsaturated fatty acids play a role in sustaining the proliferation of FGF-stimulated SC-3 cells.

Proliferation of Shionogi carcinoma 115 cells by glucocorticoid-induced autocrine heparin-binding growth factor(s) in serum-free medium.

Shionogi carcinoma 115 (SC115) has been accepted for 20 years as an androgen-responsive mouse mammary tumor. Recently, the growth of the tumor was also found to be stimulated by pharmacological, but not physiological, doses of glucocorticoid. In a serum-free culture system [Ham's F-12:Eagle's minimal essential medium (1:1, v/v) containing 0.1% bovine serum albumin], we have established that 10(-8) M testosterone, or 10(-6) M dexamethasone significantly stimulates the growth of SC-3 cells (a cloned cell line from a SC115 tumor) via androgen and glucocorticoid receptors, respectively. Recently, we demonstrated that the testosterone-induced growth of SC-3 cells is mediated through autocrine fibroblast growth factor (FGF)-like peptide(s). In the present study, mechanisms of glucocorticoid-induced growth of SC-3 cells were investigated. Serum-free conditioned medium obtained from 10(-6) M dexamethasone-stimulated SC-3 cells was fractionated by heparin-Sepharose affinity chromatography; one sharp peak of growth-stimulatory activity for SC-3 cells, eluted at 1.3 M NaCl, was identified. When the peak fraction was added to serum-free medium, the shape of SC-3 cells changed from an epithelial to a fibroblast-like appearance, similar to that induced with testosterone or basic (b)FGF. Furthermore, the growth-stimulatory activity induced with the peak fraction as well as testosterone or bFGF was markedly inhibited by anti-bFGF antibody immunoglobulin G (75 to 90% inhibition was obtained), and the specific binding of 125I-bFGF on SC-3 cells was significantly inhibited by the peak fraction. These results suggest that the glucocorticoid-induced growth of SC-3 cells is also mediated through FGF-like peptide(s) in an autocrine mechanism, which is very similar to that induced by testosterone, if not identical.

Growth-stimulating effect of pharmacological doses of estrogen on androgen-dependent Shionogi carcinoma 115 in vivo but not in cell culture.

Shionogi carcinoma 115 (SC115) had been accepted for 20 years as an androgen-dependent mouse mammary tumor, the growth of which is stimulated only by androgen. However, we very recently found that the growth of SC115 tumors in vivo is stimulated not only by physiological doses of androgen but also by pharmacological doses of estrogen through the estrogen receptor system. In the present study, the growth-stimulative effect of estrogen on an androgen-dependent cloned cell line (SC-3) derived from SC115 cells, which showed androgen- and estrogen-dependent growth in vivo, was examined in vitro. In serum-supplemented medium (Eagle's minimum essential medium containing 2% steroid-free fetal calf serum), testosterone or 5 alpha-dihydrotestosterone (10(-9)-10(-6) M) significantly stimulated the growth of SC-3 cells (3.2-fold increase in cell number at day 10 in culture containing 10(-8) M androgens) and changed the shape of SC-3 cells from epithelial to spindle (fibroblast-like), whereas 17 beta-estradiol (10(-12)-10(-6) M) even in high concentrations had no such effects on SC-3 cells. Contrary to the effect of 17 beta-estradiol in vivo, 17 beta-estradiol as well as cyproterone acetate (10(-8)-10(-6) M) inhibited the growth-stimulative effect of testosterone (10(-8) M) on SC-3 cells in a dose-dependent manner in the serum-supplemented medium. The anti-androgen and 17 beta-estradiol also showed comparable competitive effects on [3H]testosterone binding to androgen receptor in SC-3 cells. In serum-free medium [Ham's F-12:Eagle's minimum essential medium (1:1, v/v) containing 0.2% bovine serum albumin], testosterone [10(-8) M] also markedly stimulated the growth of spindle-shaped SC-3 cells, and epidermal growth factor (1 ng/ml) enhanced the growth-stimulative effect of testosterone, whereas 17 beta-estradiol (10(-8)-10(-6) M) in the absence or presence of epidermal growth factor had no growth-stimulative effect on SC-3 cells. We conclude that the growth of SC115 cells is stimulated by either physiological doses of androgen or pharmacological doses of estrogen in vivo but only by androgen in cell culture.

Inhibitory and stimulatory effects of glucocorticoid on androgen-induced growth of murine Shionogi carcinoma 115 in vivo 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 in vivo and in cell culture. However, we recently found that the growth of SC115 is also stimulated by pharmacological, but not physiological, doses of glucocorticoid both in vivo and in cell culture and by pharmacological doses of estrogen only in vivo. In the present study, therefore, we investigated the effect of dexamethasone on androgen-induced growth of SC115 cells in vivo and in cell culture. 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) estimated by cell number and DNA synthesis reached a plateau at 10(-8) M testosterone (up to 93-fold) or 10(-6) M dexamethasone (up to 7.2-fold); high stimulation induced by higher than 10(-8) M testosterone was inhibited by the addition of 10(-5)-10(-8) M dexamethasone in a concentration-dependent manner, whereas low stimulation induced by lower than 10(-10) M testosterone was significantly enhanced by the addition of dexamethasone. The presence of typical glucocorticoid and androgen receptors in SC-3 cells was also demonstrated; dexamethasone did not bind to androgen receptor and testosterone did not bind to glucocorticoid receptor. In castrated mice, the concomitant administration of dexamethasone again significantly inhibited the high growth of SC115 tumors induced by high doses of androgen but significantly enhanced the low growth induced by low doses of androgen. The present results demonstrate both inhibitory and stimulatory effects of glucocorticoid on androgen-induced proliferation of SC115 cells in cell culture and probably in vivo.

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.