Biomedical subjects

B Sato

Publications and source records attributed to B Sato.

At least 73 records · Page 4Linked to original sources

PubMed1992

Cloning and characterization of an androgen-induced growth factor essential for the androgen-dependent growth of mouse mammary carcinoma cells.

An androgen-dependent mouse mammary carcinoma cell line (SC-3) requires androgen for growth stimulation. We have shown previously that androgen acts on SC-3 cells to induce secretion of a fibroblast growth factor (FGF)-like growth factor, which in turn stimulates growth of the cells in an autocrine manner. In this study, the androgen-induced growth factor (AIGF) was purified from a conditioned medium of SC-3 cells stimulated with testosterone. cDNA cloning of AIGF by use of its partial amino acid sequence data revealed that AIGF is a distinctive FGF-like growth factor. An AIGF cDNA (pSC17) encodes a 215-amino acid protein with a putative signal peptide, which shares 30-40% homology with known members of the FGF family. The AIGF mRNA was markedly induced by 10 nM testosterone in Northern blot analysis. Expression of AIGF cDNA in mammalian cells clearly showed remarkable stimulatory effects of AIGF on growth of SC-3 cells in the absence of androgen. Thus, it is clear that the androgen-induced growth of SC-3 cells is mediated in an autocrine manner by AIGF, which is secreted by the tumor cells themselves in response to hormonal stimuli.

Amino Acid Sequence↗

PubMed1992

Characterization of the promoter region of the murine fibroblast growth factor receptor 1 gene.

To obtain some clue for the regulatory mechanism by which fibroblast growth factor (FGF) receptor 1 (FGFR 1) gene is expressed, we have cloned the promoter region of this gene from genomic library of mouse FGF-responsive cell lines. The genomic clone isolated here includes the FGFR 1 gene from position -868 to +697 relative to transcription initiation site. Sequence analysis reveals the presence of various consensus sequences for the binding sites of transcriptional factors such as SP 1, GCF, Oct-I, AP 1 and AP 2, but the absence of TATA and CAAT sequence motif. The transfection of this promoter-CAT constructs into NIH 3T3 cells demonstrates its promoter activity which is at least located between base -106 and +104.

3T3 Cells↗

PubMed1992

Nucleotide sequence of cDNA for the eclosion hormone of the silkworm, Bombyx mori, and the expression in a brain.

The cDNAs encoding eclosion hormone (EH) of the silkworm, Bombyx mori, were isolated and sequenced. The results showed that the pre-EH molecule contains a 26-amino acid signal peptide and a 62-amino acid mature EH. The deduced amino acid sequence agreed with that previously determined by the peptide analysis. The presence of leucine residue at the carboxyl terminal of EH, which had not been detected directly by the peptide analysis, was proved. Primer extension and Northern hybridization analyses revealed that 0.9 kb mRNA is transcribed and it has a 66-nucleotide non-translated sequence at the 5'-end region. In situ hybridization showed that the EH gene is expressed in two pairs of nuerosecretory cells in the brain of 5th instar larva.

Amino Acid Sequence↗

PubMed1992

Effects of retinoic acid on estrogen- and thyroid hormone-induced growth in a newly established rat pituitary tumor cell line.

In order to elucidate the complex mechanism(s) of action of steroid hormones, thyroid hormone and retinoic acid in pituitary mammotrophs, a clonal cell line (G3) was isolated from the rat pituitary tumor MtT/F84. G3 cells were found to secrete prolactin constitutively and to contain receptors for estrogen, glucocorticoid, progesterone and thyroid hormone. Stimulation of G3 cells with thyroid hormone resulted in a modest but significant increase in estrogen and progesterone receptor levels, however, retinoic acid treatment had no effect. Simultaneous addition of thyroid hormone and estrogen showed an additive effect on progesterone receptor levels in G3 cells. Thyroid hormone as well as estrogen enhanced the growth of G3 cells. Interestingly, retinoic acid was also found to enhance their growth but its enhancement was less potent than thyroid hormone and estrogen. Low concentrations of estradiol and thyroid hormone showed additive effects, but G3 cells stimulated with high concentrations of thyroid hormone failed to elicit an additive effect with estrogen, suggesting the presence of a common pathway in the growth-stimulatory actions of these hormones. In addition, exposure of G3 cells to retinoic acid completely abolished the effects of estrogen or thyroid hormone in terms of cell growth. These results suggest that there are complex interactions in the signalling pathways for estrogen, thyroid hormone and retinoic acid action in G3 cells.

Animals↗

PubMed1992

Interaction of DP-TAT-59, an active metabolite of new triphenylethylene-derivative (TAT-59), with estrogen receptors.

DP-TAT-59, (Z)-2-(4-(1-(4-hydroxyphenyl)-2-(4-isopropylphenyl)-1-butenyl) phenoxy)-N, N-dimethylethylamine, has been reported to inhibit estrogen-stimulated growth of MCF-7 cells as well as rat uterus at lower concentrations than the hydroxymetabolite of tamoxifen (4-OH-TAM). In the present study, the growth of mouse Leydig cell tumor, B-1F cells were also more effectively inhibited by DP-TAT-59 than 4-OH-TAM. Additionally, the expression of estrogen responsive element ligated CAT gene transfected into B-1F cells was also suppressed by DP-TAT-59. Thus, the interaction of DP-TAT-59 with estrogen receptor (ER) was characterized and compared with that of 4-OH-TAM using immature rat and bovine uteri. The dissociation constant of DP-TAT-59 to ER of immature rat uterus was 0.24 nM and was similar to that of 4-OH-TAM (Kd = 0.20 nM) and estradiol (Kd = 0.29 nM). Using sucrose density gradients, the sedimentation constant of DP-TAT-59 with bovine uterus was 4.9S, which was similar to that of estradiol (5.1S) and 4-OH-TAM (5.3S). However, the elution profile of the DP-TAT-59-ER complex from a DEAE-Sephadex column was different for both estradiol-and 4-OH-TAM-ER complexes. These results suggest that ER forms different complexes with DP-TAT-59 than estradiol or 4-OH-TAM, while the ER binding affinity of these compounds are similar to each other.

Animals↗

PubMed1992

Maintenance of androgen-, glucocorticoid- or estrogen-responsive growth in shionogi carcinoma 115 subline sustained in castrated mice with high dose of estrogen for 30 generations (3 years).

Shionogi carcinoma 115 (SC115), an androgen-dependent mouse mammary tumor, rapidly loses its androgen responsiveness after androgen withdrawal. The growth of this tumor can also be stimulated by high doses of estrogen or glucocorticoid. In the present study, the maintenance of hormone-responsive growth of SC115 tumors with a high dose of estrogen was examined in castrated male mice using an SC115 subline obtained by serial transplantations of SC115 tumors in estrogen-treated castrated mice for 3 years (30 generations) (subline E2). Seed tumors from both SC115 and subline E2 could rapidly grow in castrated mice given daily injections of testosterone propionate (TP), 17 beta-estradiol (E2), or dexamethasone (Dex) (100 micrograms/mouse/day) but not in those given vehicle alone. Although SC115 and subline-E2 tumors grown with TP or Dex showed temporary regression after steroid withdrawal, the tumors grown with E2 did not show such temporary regression. The TP-, E2-, or Dex-induced growth of subline-E2 tumors was almost the same as that of the original SC115 tumors. However, responsiveness to androgen, estrogen or glucocorticoid of both tumors disappeared within one passage in steroid-depleted castrated mice. The present findings demonstrate that the loss of responsiveness to androgen as well as to high doses of estrogen or glucocorticoid of SC115 tumors can be prevented in castrated mice not only with androgen but also with high doses of estrogen.

Animals↗

PubMed1992

Identification and characterization of high molecular weight forms of basic fibroblast growth factor in human pituitary adenomas.

Basic fibroblast growth factor (bFGF) extracted from 23 human pituitary adenomas and 2 nontumorous anterior pituitary glands was examined by Western blot analysis to elucidate their molecular forms. Four bands that specifically interacted with anti-bFGF antibody were identified at the regions of 16K, 18K, 22K, and 24K mol wt. These immunodetectable bFGFs were bound to a heparin-Sepharose affinity column and eluted with 1-2 M NaCl. These partially purified tumor extracts could stimulate dose-dependently the growth of FGF-responsive cells. Some tumors contained bFGF with a mol wt of 24 K as a dominant form. In contrast, a major form of bFGF at the region of 18K was identified in the nontumorous anterior pituitary glands. We also addressed the possible presence of FGF receptor mRNA using Northern blot analysis. Many, but not all, human pituitary adenomas were found to contain detectable levels of FGF receptor mRNA with a size of 3.5 kilobases. The present results suggest that the role of bFGF in growth and hormone secretion in human pituitary adenomas should be examined using high mol wt forms of bFGF.

Adenoma↗

PubMed1992

Intracranial and intraspinal dissemination of an ACTH-secreting pituitary tumor.

A case of a 29-year-old man with an ACTH-producing pituitary tumor disseminated into the subarachnoid space is described. After total adrenalectomy for Cushing's disease at the age of 15, Nelson's syndrome developed. Transsphenoidal adenomectomy at 17 and 21 years of age, pituitary irradiation and medical therapies with sodium valproate, baclofen and bromocriptine failed to lower his plasma ACTH level. Multiple intracranial and intraspinal tumors associated with the symptoms of left hemiparesis developed. The removal of a tumor grown at the level of C1-3 was performed with successful palliation of his symptoms. Histologically, the tumor cells showed sinusoidal, papillary and diffuse patterns with a preponderance of the former over the latter two, although the papillary pattern predominated in the primary pituitary tumor. Immunohistochemical analysis demonstrated most cells to be positive for ACTH in the metastatic tumor as well as the primary adenoma. The clinical significance of his course is discussed with a review of 11 reported cases with metastatic ACTH-producing pituitary tumors.

Adrenocorticotropic Hormone↗

PubMed1991

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.

Animals↗

PubMed1991

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.

Animals↗

PubMed1991

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.

Animals↗

PubMed1991

Expression cDNA cloning of fibroblast growth factor (FGF) receptor in mouse breast cancer cells: a variant form in FGF-responsive transformed cells.

Expression cDNA library of fibroblast growth factor (FGF)-responsive mouse breast cancer cells (SC-3) was prepared and screened using chick FGF receptor (FGF-R) cDNA as a probe. Two positive clones were isolated. Sequence analysis revealed that two clones have an identical full open reading frame. Compared with sequence data on mouse brain FGF-R, SC-3 cells were found to contain FGF-R with 12 amino acids insertion near N-terminal region. This insertion was mainly composed of hydrophobic amino acids. Additionally, the deletion of two amino acids in extracellular domain and the substitution of one amino acid in C-terminal region were identified in SC-3 cell FGF-R. Transfection of this clone into CHO cells resulted in a significant increase in basic FGF (bFGF) binding.

Amino Acid Sequence↗

PubMed1991

Up-regulation of fibroblast growth factor (FGF) receptor mRNA levels by basic FGF or testosterone in androgen-sensitive mouse mammary tumor cells.

Since we had previously shown that both basic fibroblast growth factor (bFGF) and testosterone stimulate the growth of mouse mammary carcinoma cells (SC-3) in serum-free culture, we tested the effect of bFGF or testosterone on FGF receptor mRNA levels. Northern blot analyses revealed that stimulation with bFGF resulted in a 5-fold increase in FGF receptor mRNA levels at 6-8 h followed by a decline to the unstimulated levels at 24 h. Simultaneous addition of cycloheximide blocked bFGF-induced accumulation of FGF receptor mRNA, although exposure of SC-3 cells to cycloheximide alone caused marginal increase in its basal level. Neither phorbol ester nor forskolin stimulated FGF receptor mRNA expression, but testosterone could raise FGF receptor mRNA levels. To obtain the maximum stimulation, however, testosterone required the longer stimulation period (12 h) than bFGF, suggesting that testosterone-induced FGF receptor mRNA accumulation is mediated through an induction of FGF-like growth factor.

Animals↗

PubMed1991

Heparin inhibits autocrine stimulation but not fibroblast growth factor stimulation of cell proliferation of androgen-responsive Shionogi carcinoma 115.

An androgen-responsive cloned cell line (SC-3) derived from Shionogi carcinoma 115 (SC115) has been shown to secrete fibroblast growth factor (FGF)-like peptide in response to androgen, which binds to FGF receptor and promotes the proliferation of SC-3 cells in an autocrine mechanism. Since the androgen-induced autocrine factor has a property to bind heparin, we examined the effects of heparin on the growth of SC-3 cells. Heparin was found to exhibit significant inhibition of testosterone-induced growth in a concentration-dependent manner: Approximately 50% inhibition was found at a concentration of 0.1 micrograms/ml. DNA synthesis of SC-3 cells induced by testosterone was also inhibited strongly by heparin, and less strongly by heparan sulfate and dermatan sulfate. Proliferation of SC-3 cells induced by acidic (a) or basic (b) FGF appeared not to be modulated by heparin. In contrast, heparin efficiently blocked DNA synthesis stimulated with androgen-induced growth factor in the conditioned medium from testosterone-treated cells. These results indicate that heparin inhibits autocrine loop in SC-3 cells induced by androgen. Thus, the autocrine growth factor possesses a different characteristic from aFGF and bFGF in that its bioactivities are negatively modulated by the glycosaminoglycan.

Animals↗

PubMed1991

A single nucleotide substitution in the D domain of estrogen receptor cDNA causes amino acid alteration from Glu-279 to Lys-279 in a murine transformed Leydig cell line (B-1 F).

A polymerase chain reaction method was carried out to address the possible presence of estrogen receptor (ER) mutations in murine transformed cell lines. The segment of ER cDNA coding the C and D domains was amplified and cloned into pUC 19. Mammary carcinoma cell line (SC-3) did not show any mutation in this segment. However, the sequence analysis of ER in the Leydig cell line (B-1 F) revealed a single base change at acidic Glu-279 (GAA) to basic Lys-279 (AAA) compared with murine uterus ER cDNA. The biological significance of this mutation is discussed.

Amino Acid Sequence↗

PubMed1991

Non-classical androgenic actions of RU38486 in androgen-responsive Shionogi carcinoma 115 cells in serum-free culture.

Antiglucocorticoid and antiprogestin RU38486 (RU486) stimulated the growth of highly androgen- and moderately glucocorticoid-sensitive SC-3 cells (a cloned cell line from Shionogi mouse mammary carcinoma 115) in a dose-dependent manner. A maximal 8-fold stimulation of growth by RU486 has been observed at 10(-7) M in a serum-free medium and its potency has been found to be almost the same as that of dexamethasone (Dex). The growth rate of SC-3 cells treated by triamcinolone acetonide (TA) or Dex combined with RU486 at 10(-9)-10(-7) M was enhanced compared to cells treated by TA or Dex alone, indicating that RU486 had additive rather than antagonistic effects. Our previous study revealed that RU486 could compete with the specific uptake of [3H]testosterone in intact SC-3 cells at relatively low affinity and the present study showed that the stimulatory effect of RU486 on the growth of SC-3 cells was significantly inhibited by pure antiandrogen flutamine and that half-maximal inhibition by flutamine was achieved at 10(-6) M. Moreover, we demonstrated that the conditioned medium from RU486-stimulated SC-3 cells contained growth-promoting activity which caused a 3.5-fold increase in DNA synthesis by SC-3 cells in the absence of RU486 and which was abolished by treatment with heparin-Sepharose. These results indicate that RU486-induced growth of SC-3 cells may be expressed as an androgenic activity through androgen receptor and mediated by a heparin-binding growth factor.

Animals↗

PubMed1991

Functional abnormality of glucocorticoid receptor in Shionogi carcinoma 115 cells as evidenced by gene transfer experiments.

The assay systems for steroid receptor functions in steroid-sensitive cells (SC-3 cells) were developed in which hormone-responsive element linked to a reporter gene [chloramphenicol acetyl transferase (CAT) gene] was transfected by the electroporation technique. Stimulation with androgen of SC-3 cells transfected with mouse mammary tumor virus promoter-CAT gene (MMTV-CAT) resulted in clear enhancement of CAT activity, whereas glucocorticoid required abnormally high concentrations to obtain significant stimulation. The simultaneous addition of glucocorticoid surprisingly inhibited androgen-induced CAT activity in SC-3 cells, whereas glucocorticoid and androgen acted together synergistically to activate CAT activity in T 47D cells. When SC-3 cells were cotransfected with the expression vector of human glucocorticoid receptor (GR) gene, inhibition with glucocorticoid of androgen-enhanced CAT activity was abolished. These results would suggest that SC-3 cells contain functionally abnormal GR.

Animals↗

PubMed1991

[Histopathological study of aortic wall dissection].

To determine the etiology of aortic wall dissection, a histopathological study of the aorta in 20 cases with dissecting aortic aneurysm (DA), 3 cases with Marfan syndrome and 3 cases with annulo-aortic ectasia (AAE) was performed. Controls consisted of 348 cases of normally-aging aorta. In cases with aortic wall dissection, the histopathological changes in the undissected media were also carefully examined. In Marfan syndrome and AAE, there was a marked accumulation of acid mucopolysaccharide (AMPS) and its distribution in the wall was diffuse in patients under 50 years old, resulting in changes in elastic fibers including fragmentation, elastolysis and reticulation. In contrast, DA was histopathologically characterized by zonal fibrosis and abnormally-dilated vessels in the aortic media. These lesions were found in 8 (40%) of the 20 DA cases. The remaining 12 cases also had increased vascularization and fragmentation of elastic fibers. This medial fibrosis and increased vascularization were particularly marked in older patients. Among the 3 diseased entities responsible for aortic wall dissection, DA differed distinctly from Marfan syndrome or AAE as to the amount and site of AMPS accumulation in the media as well as fibrosis and hypervascularity in the outer half of the aortic media. In conclusion, aortic wall dissection in younger patients may be etiologically associated with the increased AMPS accumulation in the aortic media which may always be accompanied by degeneration of elastic fibers in this study, however, in older patients zonal fibrosis and abnormal vessels developing in the media are responsible for the dissection.

Adolescent↗