Biomedical subjects

S Sumitani

Publications and source records attributed to S Sumitani.

27 records · Page 2Linked to original sources

PubMed1994

Thyroid hormone inhibits androgen-enhanced DNA synthesis in Shionogi carcinoma 115 cells without affecting autocrine growth factor mRNA expression.

The growth of the mouse mammary Shionogi carcinoma 115 (SC 115)-derived cell line (SC-3) is markedly stimulated by androgen through induction of a heparin-binding growth factor termed androgen-induced growth factor (AIGF). This androgen-induced growth is partly blocked by thyroid hormone(s) such as triiodothyronine (T3). Transforming growth factor beta 1 (TGF beta 1) also inhibits the growth of SC-3 cells. Thus, we have investigated the possibility that T3 exerts its inhibitory effects on SC-3 cell growth through an alteration in AIGF or TGF beta 1 mRNA expression. Unexpectedly, T3 failed to modulate the expression of AIGF mRNA. T3 was also unable to significantly affect TGF beta 1 mRNA levels in androgen-stimulated SC-3 cells. More importantly, a neutralizing antibody against TGF beta 1 could not block T3-dependent inhibition of androgen-induced SC-3 cell growth. However, the inhibitory ability of T3 was potentiated by TGF beta 1. In addition, T3 treatment resulted in a significant inhibition of AIGF-induced DNA synthesis. Thus, T3 treatment renders SC-3 cells somehow refractory to AIGF. The signal pathway for T3 to reduce AIGF responsiveness may be shared by TGF beta 1.

Animals↗

PubMed1994

[A case of Larsen syndrome with severe cervical cord compression].

We reported a case of Larsen syndrome with cervical cord compression. She had a flattened face, bilateral joint dislocations of the elbows, hips and knees, and equinovalgus deformity on the feet. At first she had flaccidity of the upper and lower limbs, she gradually developed spastic. On laboratory examination, CSF protein was elevated. EMG showed fibrillation. In short latency somatosensory evoked potential (SSEP), N 20 was not detected. MRI showed a severe cervical cord compression. Cervical spine deformity has been often described in the previous reports on Larsen syndrome, but cervical cord compression demonstrated by MRI was reported in only one case. We should take into consideration this risk associated with Larsen syndrome.

Abnormalities, Multiple↗

PubMed1993

Suramin interrupts androgen-inducible autocrine loop involving heparin binding growth factor in mouse mammary cancer (Shionogi carcinoma 115) cells.

The androgen-dependent clonal cell line SC-3, derived from Shionogi carcinoma 115, secretes a fibroblast growth factor (FGF)-like autocrine growth factor in response to androgen, which is able to bind to FGF receptors. In SC-3 cells, FGF receptor expression is upregulated by the SC-3-derived growth factor, providing a means of amplifying an autocrine loop of cell growth. In the present investigations, the effects of the polysulfonated naphthylurea suramin on this autocrine loop and its amplification in SC-3 cells were studied. Suramin inhibited androgen-dependent growth of SC-3 cells in a concentration-dependent fashion: approximately 50% inhibition was observed at 25 microM. [3H]Thymidine incorporation into the cells stimulated with partially purified SC-3-derived growth factor was inhibited by suramin in a similar way. Additionally, suramin inhibited acidic (a) or basic (b) FGF-induced cell proliferation, though relatively high concentrations were necessary to achieve the maximal inhibition. Pretreatment of SC-3 cells with suramin decreased cell surface 125I-bFGF binding without altering dissociation constant (Kd) of the binding sites. When the cells were incubated with 250 microM suramin for 24 h, the maximum binding (Bmax) decreased to almost 50% of the control. Treatment with suramin also decreased the levels of FGF receptor-1 mRNA to a similar extent, whereas it appeared not to affect the levels of beta-actin mRNA. Moreover, suramin completely blocked androgen- or bFGF-induced accumulation of FGF receptor-1 mRNA. The inhibitory effects of suramin on FGF receptor expression were reversed by simultaneous addition of high concentrations of bFGF. These results indicate that suramin exerts its potent antiproliferative action on SC-3 cells through inhibition of an androgen-inducible autocrine loop involving SC-3-derived growth factor and FGF receptor.

Animals↗

PubMed1993

Androgen-induced growth factor and its receptor: demonstration of the androgen-induced autocrine loop in mouse mammary carcinoma cells.

SC-3 cells derived from mouse mammary carcinoma (Shionogi carcinoma 115) exhibit remarkable growth enhancement and cell morphology change in response to androgen stimuli. These events are mediated through an androgen-induced growth factor (AIGF). Amino acid sequence deduced from cDNA reveals that AIGF has 215 amino acids with a signal peptide and scattered regions homologous to fibroblast growth factor (FGF) family proteins. The biological ability of AIGF to stimulate SC-3 cell growth is inhibited by heparin or suramin. More importantly, antisense oligodeoxynucleotide of AIGF can block androgen-induced growth of SC-3 cells. Upon synthesis under the control of androgen, AIGF is immediately secreted into the extracellular space without intracellular accumulation. At the early phase (18-24 h) of androgen stimulation, however, AIGF is mainly associated with the glycosaminoglycan on the cell surface or extracellular matrix. In addition, treatment of SC-3 cells with sulfation blocker (chlorate) or heparitinase results in the abolishment of their ability to respond to androgen or AIGF, indicating that heparan sulfate has important roles for condensing AIGF on or near the cell surface as well as potentiating the biological activity of AIGF. Then, AIGF can bind to the FGF receptor. Northern blot analysis and cDNA cloning indicate that SC-3 cells predominantly express the FGF receptor 1 with some altered amino acid sequences. Transfection of expression vectors of AIGF and this variant form of FGF receptor 1 into FGF receptor-negative myoblast cells (L 6 cells) confirms that a variant form of FGF receptor 1 is a receptor of AIGF. These results clearly demonstrate that an autocrine mechanism is operating in androgen-induced growth of SC-3 cells.

Amino Acid Sequence↗

PubMed1993

A role for heparan sulfate in androgen-induced deoxyribonucleic acid synthesis of mouse mammary carcinoma (Shionogi carcinoma 115)-derived SC-3 cells.

In response to androgen stimuli, SC-3 cells cloned from mouse mammary carcinoma (Shionogi carcinoma 115) secrete heparin-binding growth factor, which is able to bind to fibroblast growth factor (FGF) receptor, ultimately resulting in SC-3 cell proliferation. A role for glycosaminoglycan in the process of this androgen-induced autocrine loop was examined. When quiescent SC-3 cells were stimulated with testosterone, enhanced DNA synthesis was demonstrated even at the early phase (12-24 h) of stimulation. During this early period, autocrine growth-promoting activity was found to be associated with cell surface and extracellular matrix, but not to be present in the conditioned medium. This bound form of growth-promoting activity was able to be extracted with 2 M NaCl (pH 7.5) and absorbed onto a heparin-Sepharose affinity column, from which it was eluted at a concentration of 1.1-1.3 M NaCl. Extracted growth factor, whose activity was partially blocked by anti-basic FGF antibody, up-regulated the expression of FGF receptor-1 mRNA. These characteristics were similar to those of a soluble form of SC-3-derived growth factor previously reported from our laboratory. Androgen-induced enhancement of DNA synthesis was inhibited by simultaneous treatment of SC-3 cells with 10 mIU/ml heparitinase or 25 mM sodium chlorate (an inhibitor of phosphoadenosine sulfate synthesis). However, chlorate treatment did not affect the synthesis and distribution of androgen-induced growth factor, suggesting that the response of chlorate-treated cells to this growth factor was impaired. These results indicate that heparan sulfate has important roles in concentrating androgen-induced heparin-binding growth factor on or very close to the cell surface and in potentiating its bioactivity.

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

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

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↗

PubMed1985

Visualization of the cerebrospinal fluid drainage into the Galen's vein.

Arachnoid granulations are not always present in lower mammals and primate newborns. In order to visualize the route for the cerebrospinal fluid (CSF) to drain into the venous system, horseradish peroxidase (HRP) was injected into the lateral ventricle or cisterna cerebellomedullaris of the mouse and rat. From 30 to 60 min after the commencing of a slow infusion for 15-30 min of 0.05-0.1 ml solution containing 10-20 mg HRP, the mouse, whose skull had been exposed, was dropped into cold acetone at dry ice temperature; other animals were fixed by perfusion with aldehyde solution. The frozen head was dissected in a cryostat kept at -18 degrees C to remove the skull, but leave the dura mater and the falx cerebri. The brain with meninges was cut into 30-45 microns sagittal sections in the cryostat, and processed for peroxidase reaction. The perfusion-fixed brains were used for scanning electron microscopy and for electron microscope observation of the tracer. The reaction product was found within fenestrated venous capillaries of the choroid plexus. The route for the HRP in the CSF to drain into the sinus rectus via the vena choroidea and vena cerebri magna was directly visualized in the mouse.

Animals↗