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Biomedical subjects

R Horiuchi

Publications and source records attributed to R Horiuchi.

At least 37 records · Page 2Linked to original sources
PubMed1994

Modulation of adriamycin resistance in human breast carcinoma MCF-7 cells in vitro and in vivo by medroxyprogesterone acetate.

The combination effect of adriamycin (ADM) and medroxyprogesterone acetate (MPA) was examined in vitro against human breast carcinoma MCF-7 and its ADM-resistant line (MCF-7/ADM). MCF-7 cells, which are positive for estrogen receptors, progesterone receptors and high-affinity MPA-binding activity, were more susceptible to the growth-inhibitory activity of ADM or MPA than MCF-7/ADM cells. A combination effect of ADM and MPA was observed against MCF-7/ADM cells, which are negative for steroid receptors, and furthermore against human nasopharynx carcinoma KB and its ADM-resistant line KB-A1. This combination effect of ADM and MPA against MCF-7/ADM cells was demonstrated to be synergistic by using the median effect plot method. The activity of MPA was almost equivalent to that of chlormadinone acetate or tamoxifen, greater than that of progesterone, and less than that of verapamil. The accumulation of ADM in MCF-7/ADM cells was enhanced by treatment with 10 microM MPA as well as 10 microM verapamil. The efflux of accumulated ADM from MCF-7/ADM cells was also partially inhibited by treatment with MPA or verapamil. MPA augmented the growth-inhibitory activity of ADM against MCF-7/ADM tumors inoculated into nude mice, although statistical significance was not observed. It is suggested that the clinical advantage of the combination of MPA with ADM against advanced breast cancers may be partly explained by the modulation of ADM resistance by MPA.

Animals↗
PubMed1994

Co-ordinate actions of FSH and insulin-like growth factor-I on LH receptor expression in rat granulosa cells.

The actions of FSH and Insulin-like growth factor-I (IGF-I) were studied in cultured rat ovarian granulosa cells. Cells became differentiated and expressed LH receptors when they were incubated for 72 h with 200 micrograms FSH/l (high FSH) but not 20 micrograms FSH/l (low FSH). Treatment with high but not low FSH increased the release of both immunoreactive and bioactive IGF-I into the medium. A combination of low FSH and IGF-I reproduced the effect of high FSH on LH receptor expression. We then examined the critical time when low FSH and IGF-I exerted their effects. In the presence of continuous low FSH, IGF-I was capable of inducing LH receptor expression even when added 24 h after the addition of low FSH. However, when IGF-I was added at 36 h, LH receptor expression measured at 72 h was greatly reduced. In contrast to the action of IGF-I, continuous exposure to low FSH was required for LH receptor expression, and IGF-I had no effect when FSH was not included for the entire 72 h of culture. DNA synthesis as assessed by both [3H]thymidine incorporation and nuclear bromodeoxyuridine labelling was moderate at the beginning of culture and markedly reduced at 24 h both in the presence and absence of either high FSH or low FSH plus IGF-I. In the presence of either high FSH or a combination of low FSH plus IGF-I, DNA synthesis remained decreased for up to 72 h whereas it began to increase in the absence of either high FSH or a combination of low FSH plus IGF-I.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Human growth hormone augmentation of epidermal growth factor binding sites on rat granulosa cells.

The effect of human GH (hGH) on the regulation of epidermal growth factor (EGF) receptor was investigated during differentiation of FSH-treated rat granulosa cells, which has been reported to be mediated by a cAMP-dependent mechanism. By measuring the binding of [125I]iodo-EGF to the intact cells, FSH was shown to cause increases in the number of EGF binding sites after culture for 72 h. When granulosa cells were cultured with hGH, the number of FSH-induced EGF binding sites was augmented, with a half-maximal effect at about 10 micrograms hGH/l and a maximal stimulatory concentration of 100 micrograms/l. The stimulatory effect of hGH was absolutely dependent on insulin which by itself showed stimulatory effects on EGF binding sites. Scatchard analysis of EGF binding sites indicated that treatment with hGH increased the number of EGF binding sites (17,200 sites/cell after treatment with FSH; 31,700 sites/cell after FSH plus hGH), but did not alter the binding affinity. The augmentation was observed after culturing for 48 h and increased progressively with time, reaching 280% of the level after FSH treatment by 120 h. Although progesterone synthesis was increased by hGH, the markers of cell differentiation such as cAMP synthesis and LH binding sites were suppressed, indicating hGH inhibition of the cAMP-mediated signal. The action of hGH on the EGF binding sites was not accompanied by cell proliferation. These findings indicate that hGH has a novel action on the regulation of rat granulosa cell EGF binding sites and that the granulosa cell may possess both cAMP-dependent and -independent mechanisms for expression of EGF binding sites.

Animals↗
PubMed1994

[Molecular cloning and multifunctions of membrane-associated 3,5,3'-triiodo-L-thyronine binding protein with protein disulfide isomerase activity].

The protein or cDNA sequencing revealed that the membrane-associated 3,5,3'-triiodo-thyronine binding protein (T3BP) acts as a multifunctional protein:protein disulfide isomerase (PDI) catalyzing isomerization of intra- and inter-molecular disulfide bridge in the proteins, beta-subunit of prolyl 4-hydroxylase catalyzing the formation of 4-hydroxyproline in collagen molecules, glycosylation site binding protein which is a component of oligosaccharyl transferase transferring oligosaccharide chains to the asparagine residues of Asn-X-Ser/Thr site in nascent polypeptide, and a component of triglyceride transfer protein complex involved in the transfer unit of triglyceride, cholesteryl ester and phosphatidylcholine between biomembranes. The functions of 55 k-T3BP/PDI, mainly involved in important post-translational modifications, are discussed in relation to the domain structure of the molecule.

Amino Acid Sequence↗
PubMed1993

Identification of protein disulfide isomerase and calreticulin as autoimmune antigens in LEC strain of rats.

Long Evans Cinnamon (LEC) rats, showing spontaneous hereditary hepatitis and hepatic carcinoma, were found to possess autoimmune antibodies to liver microsomal proteins, particularly to proteins with the molecular weight of 56kD and 55kD. The antibodies occurred in association with acute lethal hepatitis in the LEC rats in our previous study. Two-dimensional immunoblot analysis of the antigenic proteins revealed that the 56kDa and 55kDa proteins showed 4.2 and 4.0 pI values and were estimated to be protein disulfide isomerase (PDI) and calreticulin, respectively, from NH2-terminal amino acid sequence analysis. These proteins were further identified by immunoblot analyses using purified proteins and specific antibodies. PDI was a major autoimmune antigenic protein.

Amino Acid Sequence↗
PubMed1993

Purification and characterization of a 3,5,3'-L-triiodothyronine-specific binding protein from bullfrog tadpole plasma: a homolog of mammalian transthyretin.

We analyzed the nature of the thyroid hormone-binding proteins in bullfrog plasma using N-bromoacetyl-[125I]T3 as an affinity labeling probe. Polyacrylamide gel electrophoresis under nondenaturing conditions of the bullfrog N-bromoacetyl-[125I]T3-labeled plasma proteins revealed two proteins with specific binding to T3. A labeled protein that migrated faster than albumin (T-T3BP) was detected only in plasma obtained from tadpoles at stages earlier than, but not at the end of, metamorphic climax. Another protein that migrated more slowly than albumin appeared in the plasma at the late climax stage and was present in the adult stage. To study the function of T-T3BP during metamorphosis, it was purified from tadpole plasma to the single protein. The molecular mass of this protein was estimated to be 56 kilodaltons by gel filtration, but only 16 kilodaltons by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, which indicates that the molecule comprised four identical subunits. The amino acid composition of T-T3BP and the amino acid sequence of its N-terminal portion were highly homologous with those of mammalian transthyretins. These molecular features indicate that T-T3BP is a homolog of mammalian transthyretins. However, in contrast to mammalian transthyretins, the affinity of bullfrog transthyretin for T3 was 360 times higher than that for T4. Scatchard analysis revealed that T-T3BP possessed a single class of T3-binding site, with a Kd of 0.67 nM at 0 C. These results suggest that bullfrog transthyretin may play an important role in transporting T3 in the blood during metamorphosis.

Affinity Labels↗
PubMed1993

[Effect of medroxyprogesterone acetate on the anticellular activity of 5-fluorouracil against human breast and stomach cancer cells].

As 5-fluorouracil (5-FU) has been known to show clinically antitumor effects against both breast and stomach carcinomas. We compared the combined effects of medroxyprogesterone acetate (MPA) with 5-FU on the growth of cultured human breast and stomach carcinoma cells. MPA inhibited the growth of estrogen-dependent human breast carcinoma MCF-7 cells at the low concentrations and exhibited an additive effect in combination with 5-FU. MPA also inhibited the growth of human stomach carcinoma MKN-45 cells at relatively high concentrations and exhibited an additive effect in combination with 5-FU. Human stomach carcinoma MKN-28 cells were rather insensitive to MPA, but, an additive combination effect of MPA and 5-FU was observed. These three cell lines were found to have MPA-binding proteins which may be distinct from the nuclear progesterone receptor, suggesting the correlation with growth-inhibitory activity of MPA.

Breast Neoplasms↗
PubMed1992

Enhancement of ganglioside GM3 synthesis in okadaic-acid-treated granulosa cells.

Okadaic acid is a potent inhibitor of type-2A (PP2A) and type-1 (PP1) protein phosphatases and has been proved to be a valuable tool for studies on the protein phosphorylation. We have investigated the effects of okadaic acid on rat granulosa cells in order to determine whether the regulation of ganglioside synthesis involves protein phosphorylation via inhibition of PP2A and PP1. Granulosa cells expressed luteinizing hormone (LH) receptors, measured as the binding of 125I-deglycosylated human chorionic gonadotropin (hCG) to intact cells, and synthesized the gangliosides NeuAc alpha 2-->3Gal beta 1-->4Glc beta 1-->1Cer (GM3) and Gal beta 1-->3GalNAc beta 1-->4[NeuAc alpha 2-->3]Gal beta 1-->4Glc beta 1-->1Cer (GM1), demonstrated by metabolic labeling of glycosphingolipids with [3H]galactose, in response to follicle-stimulating hormone (FSH). When FSH-stimulated granulosa cells were treated with 10 nM okadaic acid for 15 h, down-regulation of LH receptors, dissociation of LH receptor-effector coupling and significant decreases of intracellular and extracellular 3',5'-cyclic adenosine monophosphate (cAMP) levels were observed. The okadaic acid-induced desensitization to gonadotropin in granulosa cells was accompanied by increased ganglioside synthesis. The amount of 3H-labeled ganglioside GM3, the major ganglioside (about 95% of the total) synthesized by mature granulosa cells, was enhanced in okadaic acid-desensitized cells (to 215% of the control value) and in those desensitized by hCG (by 354%), forskolin (by 190%) and 12-O-tetradecanoylphorbol 13-acetate (by 143%). The results of this study suggest that an increase in the phosphorylation state of cells is accompanied by enhancement of ganglioside synthesis.

Animals↗
PubMed1992

Amyotrophic lateral sclerosis with ophthalmoplegia and multisystem degeneration in patients on long-term use of respirators.

We describe two patients with sporadic amyotrophic lateral sclerosis (ALS), who had developed progressive external ophthalmoplegia of a predominantly supranuclear type while they survived on respirators, and displayed histopathological abnormalities both typical and atypical of ALS. Patient 1 was a 43-year-old man with ALS of 5-year duration, who had initially exhibited fulminant ALS, and remained on a respirator for 4 years. Patient 2 was a 51-year-old man with ALS of 13-year duration, who remained on a respirator for 8 years. Both patients died in a "totally locked-in state". Autopsy of both patients revealed not only histopathological abnormalities consistent with ALS, but also multisystem degeneration which involved the pontine tegmentum, substantia nigra, Clarke's dorsal nuclei and spinocerebellar tracts. In addition, Patient 2 displayed intracytoplasmic neuronal basophilic inclusion bodies which exhibited marked immunoreactivity to anti-ubiquitin antibodies. Our case reports indicate that the longer survival which is possible through the use of respirators may make one subgroup of ALS patients prone to develop atypical clinical and neuropathological features which are not observed during the natural course of ALS.

Adult↗
PubMed1992

1 alpha-hydroxyvitamin D3, hypercalcemia, and growth suppression of 7,12-dimethylbenz[a]anthracene-induced rat mammary tumors.

1 alpha-hydroxyvitamin D3 [1 alpha(OH)D3] was administered to female Sprague-Dawley rats with 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary tumors. 1 alpha(OH)D3 suppressed the growth of the rat mammary tumors dose-dependently, and in the high dose groups treated with 0.5-1.0 micrograms/kg of 1 alpha(OH)D3, significant inhibition of tumor growth was observed. But daily oral administration of 1 alpha(OH)D3 for four consecutive weeks caused side effects such as hypercalcemia and weight loss. We compared 0.5 microgram/kg of 1 alpha(OH)D3 three times weekly with the same dose six times weekly to discover whether or not the side effects can be reduced by treatment schedule. Both groups showed a significant oncostatic effect, compared with the control group, while the side effects were relieved in the three times weekly group. Regarding estrogen receptors (ER) in the tumors, there was no significant difference among the groups. These results suggested that the antitumor effect of 1 alpha(OH)D3 on DMBA-induced mammary tumors was not related to ER status. Combined use of 1 alpha(OH)D3 with 5-fluorouracil (5-FU) or medroxyprogesterone acetate (MPA) was also examined. No significant augmentation of the antitumor effect was seen in the two combinations, although the combined therapy with MPA showed a significant inhibition of weight loss in the rats.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1992

Biphasic effects of exogenous ganglioside GM3 on follicle-stimulating hormone-dependent expression of luteinizing hormone receptor in cultured granulosa cells.

The major ganglioside NeuAc alpha 2-->3Gal beta 1-->4Glc beta 1-->1Cer (GM3) present in cultured rat granulosa cells was examined for potential function in the expression of luteinizing hormone (LH) receptor on the cell surface in response to follicle-stimulating hormone (FSH). Synthesis of GM3 was stimulated concentration-dependently by FSH, and the stimulation was enhanced synergistically by insulin, as revealed by metabolic labeling of glycosphingolipids with [3H]galactose. When granulosa cells were cultured in the media containing GM3 (0.2-20 microM), biphasic changes in FSH-dependent expression of LH receptor were observed, as measured by the binding of 125I-deglycosylated human choriogonadotropin to the intact cells. Exogenous GM3 suppressed expression of LH receptor in the cells treated with a low dose of FSH (20 ng/ml), which was characterized by a low GM3 level, to 30% of control at 10 microM, with a half-maximal inhibitory concentration of 8 microM. In contrast, in the cells treated with a high dose of FSH (100 ng/ml) and insulin, which was characterized by a high GM3 level, expression of LH receptor was enhanced by exogenous GM3, to 148% of control at 10 microM, with a half-maximal effective concentration of 2 microM. Exogenous GM3 produced concomitant changes in the levels of extracellular cAMP. These effects of exogenous GM3 were not accompanied by changes in granulosa cell proliferation. Exogenous GM3 also modulated the LH receptor expression by the synergistic action of 12-O-tetradecanoylphorbol 13-acetate with insulin, with no significant changes in cellular DNA contents, suggesting that exogenous GM3 does not modulate directly the action of FSH at its receptor sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Intersite variation of estrogen receptors in human breast cancers and response to endocrine therapy. Which section of a large tumor is the best for estrogen receptor assay?

Estrogen receptor (ER) assays were performed by sucrose gradient centrifugation method at multiple sites in large breast cancers. Intersite variation of ER in a tumor was observed in 24 out of 35 cases. 16 tumors with relatively low ER levels showed different ER status with multiple assays. The results suggest that an assay performed on a small random part of a large tumor may not yield the true ER status. ER value at the largest cross-section was almost the same as the average ER values in each tumor. In addition, 21 cases were examined in relation to ER values at multiple sites in the large tumors and response to endocrine therapy. As the ER value at the largest cross-section was highly correlated with the therapeutic response to endocrine therapy of breast cancer, it would represent true ER status and level. The results suggest that the ER assay at the largest cross-section of a large tumor is an appropriate method to predict response to endocrine therapy.

Breast Neoplasms↗
PubMed1991

Tumor-promoting phorbol ester acts synergistically with insulin to induce lutropin receptor expression in rat granulosa cells.

Lutropin (LH) receptors in rat granulosa cells are expressed by activation of cAMP-dependent protein kinase in response to follitropin (FSH). In the present study, 12-O-tetradecanoylphorbol 13-acetate (TPA) could cause a dose-dependent expression of LH receptors in the presence of insulin, but not in the absence of insulin, as measured by binding of 125I-deglycosylated human choriogonadotropin (DGhCG). The synergistic action of TPA with insulin was achieved at 1 nM and 10 mIU/ml, respectively. The receptor expression induced by this synergistic action was accompanied by cAMP accumulation which was detected after a lag time of 6 h following exposure to TPA. However, a synthetic diacylglycerol and non-protein kinase C activating phorbol derivatives did not mimic the effect of TPA on the receptor expression. In addition, insulin modulated the inhibitory effect of TPA in FSH-induced LH receptor expression, indicating a peculiar action of insulin in the receptor expression. Indomethacin treatment led to a dose-dependent inhibition in the receptor expression in the cells treated with TPA plus insulin more than that in the cells with FSH plus insulin, suggesting that the synergistic action was dependent upon cyclooxygenase and/or phospholipase A2 activity. It was shown by Scatchard analysis of LH receptors and kinetic studies of hCG-stimulated cAMP formation that the synergistic action of TPA with insulin led to expression of functional LH receptors coupled with the adenylate cyclase system in cultured granulosa cells.

Adenylyl Cyclases↗
PubMed1991

Antitumor effects of a nonsteroidal aromatase inhibitor (CGS 16949A) on 7, 12-dimethylbenz[alpha]anthracene-induced mammary tumors in rats.

The effects of a nonsteroidal aromatase inhibitor, CGS 16949A, on female Sprague-Dawley (SD) rats with 7, 12-dimethylbenz[alpha]anthracene (DMBA)-induced mammary cancers were examined in relation to estrogen receptors (ER). Rat tumor sizes in each treated group were significantly smaller (P less than 0.05) and rat body weights in most treated groups were significantly increased (P less than 0.05) compared to those in the control group (no treatment) at all measurement points during treatment. Rat uterine weights in each treated group decreased significantly compared with those in the control group (P less than 0.05). There was no significant difference between ER-positive and ER-negative groups in tumor size, body weight or uterine weight. At increased doses of CGS 16949A in the experiment, further increases in testosterone levels and further decreases in estradiol levels were shown to occur. The results suggest the mechanisms of CGS 16949A action not to be influenced by the presence or absence of ER, but to be due to its potent aromatase inhibition of the conversion of androgens to estrogens.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1991

Effects of sequential and combined immuno-endocrine therapies using OK-432 (Picibanil) and tamoxifen on the growth of 7,12-dimethylbenz [alpha] anthracene-induced rat mammary carcinoma.

Effects of sequential and combined immuno-endocrine therapies using OK-432 (Picibanil) and tamoxifen (TAM) on the growth of 7,12-dimethylbenz [alpha] anthracene (DMBA)-induced carcinoma were examined in 128 female Sprague-Dawley (SD) rats. The rats were divided into six groups: control (no treatment), tamoxifen, OK-432, simultaneous immuno-endocrine OK-432 and TAM (OK-432 + TAM) therapy, two types of sequential immuno-endocrine therapy of the OK-432 and TAM groups [OK-432 (1 wk)----TAM (4 wk) and OK-432 (2 wk)----TAM (3 wk)]. Each group was treated consecutively for five weeks. The response rates in the TAM alone group, the [OK-432 (1 wk)----TAM (4 wk)] group and the [OK-432 + TAM (5 wk)] group were significantly higher than in the control group. When the results among the treated groups were compared, the response rate in the [OK-432 (1 wk)----TAM (4 wk)] group was significantly higher than in the OK-432 alone or TAM alone groups. The response rate in the [OK-432 (2 wk)----TAM (3 wk)] group, however, was lower than in the TAM alone group. The response rate in the OK-432 + TAM group was, moreover, not significantly superior to that in the TAM alone group. These results suggest OK-432 not to potentiate the antitumor effect of TAM since the response rate of the combined OK-432/TAM therapy was not always significantly superior to that of the TAM treatment.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1990

Thyroid hormone binding protein contains glycosylation site binding protein activity.

Several lines of evidence provided by other workers indicate that within the same species thyroid hormone binding protein, the beta-subunit of prolyl hydroxylase, and protein disulfide isomerase are the same protein. We sought to determine if glycosylation site binding protein, a lumenal protein of the endoplasmic reticulum, also has the same primary structure. To accomplish this the level of glycosylation site binding protein (GSBP) activity, measured by photolabeling with a glycosylation site peptide probe, was carried out in preparations of 3T3 cells and in E. coli transformed with human thyroid hormone binding protein cDNA. The results strongly support the idea that GSBP is identical to these other lumenal proteins of the endoplasmic reticulum.

Affinity Labels↗
PubMed1990

Inflammatory pseudotumor of the liver. Clinicopathologic study and review of the literature.

Clinicopathologic analysis of nine patients with inflammatory pseudotumor of the liver was reported. The age of the patients varied from 22 to 83 years old, with a male to female ratio of 8 to 1. They complained of intermittent fever and abdominal pain, and laboratory data on admission suggested an inflammatory process. The solitary or multiple, well-defined space-occupying lesions were displayed by recently advanced imaging techniques. Partial hepatectomy, laparotomy, needle biopsy, or autopsy was performed in all nine patients with diagnoses of hepatocellular carcinoma, metastatic liver tumor, or liver abscess. Histologically, these lesions were composed of dense hyalinized fibrosis and/or infiltrating inflammatory cells constituting large numbers of foamy histiocytes, lymphocytes, and plasma cells. Obliterating phlebitis of relatively large branches of the portal vein was found, thus providing a diagnostic clue to distinction from the primary hepatic cancer by imagings. Considering the clinicopathologic features and the patients' histories, in which four patients had been in the Southeast Asian countries or India, it is possible that infection of microorganisms through the portal vein could participate in these lesions as a cause. Two patients died of causes probably related to this lesion, indicating poor prognosis in some patients, in contrast to the generally fair prognosis of previously published cases.

Adult↗