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Biomedical subjects

A Miyajima

Publications and source records attributed to A Miyajima.

At least 91 records · Page 5Linked to original sources
PubMed1997

Oncostatin M and leukemia inhibitory factor do not use the same functional receptor in mice.

Oncostatin M (OSM) and leukemia inhibitory factor (LIF) are members of the interleukin-6 (IL-6) subfamily of cytokines that use a common signal transducer gp130. Human OSM (hOSM) and LIF share a functional high-affinity receptor that is composed of gp130 and LIF receptor beta subunit (LIFRbeta). A second high-affinity receptor for hOSM was recently found to be formed by gp130 and the hOSM receptor beta subunit. However, the nature of murine OSM (mOSM) and its receptors has remained unknown. Using the recently cloned mOSM cDNA, we produced recombinant mOSM and studied its biological activity and receptor structure. Murine hematopoietic cell lines M1 and DA1.a, an embryonic stem cell line CCE, and Ba/F3 transfectants expressing gp130 and LIFRbeta responded to murine LIF (mLIF) and hOSM equally well, while these cells responded to mOSM only at a 30-fold to 100-fold higher concentration than those of mLIF and hOSM. In contrast, NIH3T3 cells responded to mOSM, but not to mLIF and hOSM. Scatchard plot analyses showed that mOSM bound to gp130 with low-affinity (kd = 2.8 to 4.2 nmol/L) and that the binding affinity did not increase in the presence of LIFRbeta. However, mOSM bound to NIH3T3 cells with high-affinity (kd = 660 pmol/L), whereas mLIF did not bind to NIH3T3 cells at all. These results indicate that unlike hOSM, mOSM and mLIF do not share the same functional receptor, and mOSM delivers signals only through its specific receptor complex. Further studies in mice will define the physiological roles of OSM.

Animals↗
PubMed1997

Erythropoietin induces tyrosine phosphorylation of the interleukin-3 receptor beta subunit (betaIL3) and recruitment of Stat5 to possible Stat5-docking sites in betaIL3.

The receptors for erythropoietin (Epo) and interleukin-3 (IL-3) both induce the ligand-dependent activation of the Jak2 tyrosine kinase. Activated Jak2 then phosphorylates these receptors and thereby recruits various signaling molecules containing the Src homology (SH)-2 domain, including Stat5, to the tyrosine phosphorylated receptors. In the present study, we demonstrate that Epo stimulation induces unidirectional cross-phosphorylation of the IL-3 receptor beta subunit (betaIL3) on tyrosines and its rapid and transient association with Stat5 in murine IL-3-dependent cell lines engineered to express the Epo receptor (EpoR). Using cell lines expressing various EpoR mutants, it was demonstrated that the Epo-induced tyrosine phosphorylation of betaIL3 is dependent on the membrane-proximal EpoR cytoplasmic region involved in the activation of Jak2, but not on the extracellular and transmembrane regions or on the carboxy-terminal 145 amino acid region containing all the intracellular tyrosine residues. It was also shown that IL-3 induces rapid and dose-dependent association of Jak2 with betaIL3. However, Epo failed to induce any detectable association of betaIL3 with Jak2 or the EpoR. The present study also demonstrates that in IL-3-stimulated cells, an ovine Stat5 mutant harboring a substitution of Tyr694 to Phe, which abolishes the tyrosine phosphorylation required for activation, fails to dimerize with endogenous Stat5, shows sustained binding with tyrosine-phosphorylated betaIL3, and inhibits the tyrosine phosphorylation of endogenous Stat5. These results suggest that betaIL3 may have Stat5 docking sites, similar to those found in the EpoR, that facilitate the activation of Stat5 by Jak2 and raise the possibility that Epo may cross-activate or transmodulate the IL-3 receptor signaling pathways.

Animals↗
PubMed1997

A possible involvement of Stat5 in erythropoietin-induced hemoglobin synthesis.

Erythropoietin (EPO) and its cell surface receptor (EPOR) play central roles in the proliferation and differentiation of mammalian erythroid progenitor cells. Recently both the tyrosine residues in the EPOR responsible for the activation of Stat5 and the role of Stat5 for EPO-dependent cell proliferation have been shown. Here, we describe the roles of Stat5 and of these tyrosine residues in the EPOR in the erythroid differentiation of murine hematopoietic cell line SKT6 which produces hemoglobin in response to EPO. Chimeric receptors carrying the extracellular domain of the EGF receptor and the intracellular domain of the EPOR were introduced into SKT6 cells. Like EPO, EGF equally activated Stat5 and induced hemoglobin. Activation of Stat5 and hemoglobin expression by EGF were markedly impaired in cells expressing the tyrosine mutated chimeric receptors. In addition, ectopic expression of the prolactin receptor, another cytokine receptor that activates Stat5, led to hemoglobin synthesis. Finally, hemoglobin synthesis was severely inhibited by overexpressing a dominant negative form of Stat5. These results collectively suggest that Stat5 plays a role in EPO-mediated hemoglobin synthesis in SKT6 cells.

Animals↗
PubMed1997

CIS, a cytokine inducible SH2 protein, is a target of the JAK-STAT5 pathway and modulates STAT5 activation.

We searched for immediate early cytokine responsive genes and isolated a novel gene, CIS (Cytokine Inducible SH2 containing protein) that is induced in hematopoietic cells by a subset of cytokines including interleukin-2 (IL-2), IL-3, and erythropoietin (EPO). The mutant IL-2 receptor that fails to activate STAT5 could not induce CIS, suggesting that STAT5 is involved in the cytokine-inducible expression of CIS. We cloned the 5'-flanking region of the CIS gene and found that about 200 bases upstream of the transcription-initiation site contain four potential STAT5 binding sites (MGF boxes). Luciferase reporter assays showed that these MGF boxes were essential for EPO-dependent promoter activity. Expression of STAT5 and the EPO receptor in HEK293 cells conferred EPO-dependent activation of the CIS promoter. These data indicate that CIS is a target of the JAK-STAT5 pathway of cytokine receptors. CIS contains an SH2 domain and binds to tyrosine-phosphorylated EPO and IL-3 receptors. In HEK293 cells expressing STAT5 and the EPO receptor, EPO-dependent tyrosine phosphorylation of STAT5, as well as EPO-dependent CIS-promoter activation, was suppressed when CIS was coexpressed. Moreover, the induction of oncostatin M, another STAT5 target, as well as the tyrosine-phosphorylation of STAT5, were partially suppressed by CIS expression in Ba/F3 cells. Thus, CIS is a feedback modulator of STAT5; its expression is induced by STAT5 and it negatively modulates STAT5 activation.

Amino Acid Sequence↗
PubMed1997

The apoptosis-inducing granulocyte-macrophage colony-stimulating factor (GM-CSF) analog E21R functions through specific regions of the heterodimeric GM-CSF receptor and requires interleukin-1beta-converting enzyme-like proteases.

The granulocyte-macrophage colony-stimulating factor (GM-CSF) analog E21R induces apoptosis of hemopoietic cells. We examined the GM-CSF receptor subunit requirements and the signaling molecules involved. Using Jurkat T cells transfected with the GM-CSF receptor we found that both receptor subunits were necessary for E21R-induced apoptosis. Specifically, the 16 membrane-proximal residues of the alpha subunit were sufficient for apoptosis. This sequence could be replaced by the corresponding sequence from the interleukin-2 receptor common gamma subunit, identifying this as a conserved cytokine motif necessary for E21R-induced apoptosis. Cells expressing the alpha subunit and truncated betac mutants showed that the 96 membrane-proximal residues of betac were sufficient for apoptosis. E21R, in contrast to GM-CSF, did not alter tyrosine phosphorylation of betac, suggesting that receptor-associated tyrosine kinases were not activated. Consistent with this, E21R decreased the mitogen-activated protein kinase ERK (extracellular signal-regulated kinase). E21R-induced apoptosis was independent of Fas/APO-1 (CD95) and required interleukin-1beta-converting enzyme (ICE)-like proteases. In contrast, Bcl-2, which protects cells from growth factor deprivation-induced cell death, did not prevent this apoptosis. These findings demonstrate the GM-CSF receptor and ICE-like protease requirements for E21R-induced apoptosis.

Amino Acid Chloromethyl Ketones↗
PubMed1997

A posterior lumbar approach for retroperitoneoscopic adrenalectomy: assessment of surgical efficacy.

OBJECTIVES: To compare the efficacy of retroperitoneoscopic adrenalectomy by a posterior lumbar approach (RPA) with that obtained by a transperitoneal anterior approach (TAA) or retroperitoneal lateral flank approach (RLA). METHODS: Fifty-one patients underwent endoscopic adrenalectomy by three approaches, including laparoscopic adrenalectomy by TAA in 33, retroperitoneoscopic adrenalectomy by RLA in 5, and retroperitoneoscopic adrenalectomy by RPA in 13. RESULTS: The average adrenal tumor size was 27 mm (range 8 to 65). The average number of trocars required for RPA was 3.2 which was significantly less than that for TAA and for RLA (4.2 and 4.1, respectively). The conversion rate to open surgery was 9.1% by TAA, 0% by RLA, and 7.7% by RPA. The average operating time for TAA was 252 minutes, which was significantly shortened to 194 minutes by RLA and 142 minutes by RPA (P < 0.02). The average blood loss was 101 mL for TAA and was negligible by RLA and RPA (22 and 32 mL. respectively). CONCLUSIONS: RPA allowed direct access to the main adrenal vascular supply before the gland was greatly manipulated. Endoscopic adrenalectomy by TAA or even by RLA required extra ports for retraction of liver, spleen, vena cava, or adrenal gland, with higher chance of vein avulsion. RPA was technically feasible and most effective for retroperitoneoscopic adrenalectomy in regard to the simplicity of vascular control. The operating time, perioperative morbidity, and cost were reduced with this approach.

Adrenal Gland Neoplasms↗
PubMed1997

Role of reactive oxygen species in cis-dichlorodiammineplatinum-induced cytotoxicity on bladder cancer cells.

This study was undertaken to investigate the intracellular induction of reactive oxygen species (ROS) by cis-dichlorodiammineplatinum (CDDP) and the augmentation of their cytotoxicity in bladder cancer cells (KU7) by enhancement of ROS generation by the glutathione (GSH) depletors buthionine sulphoximine (BSO) and diethylmaleate (DEM). CDDP-induced cytotoxicity in KU7 cells and its modulation by GSH depletors were determined using spectrophotometric measurement with crystal violet staining. The effects of GSH depletors on intracellular GSH levels were confirmed using the GSH reductase-DTNB recycling method. Intracellular ROS generation induced by CDDP with or without GSH depletors was estimated from the amount of intracellular dichlorofluorescein (DCF), an oxidized product of dichlorofluorescein (DCFH), which was measured with an anchored cell analysis and sorting system. The cytotoxic effects of CDDP (IC50 15.0 +/- 2.5 microM) were significantly enhanced by BSO (IC50 9.3 +/- 2.6 microM, P < 0.01) and DEM (IC50 10.3 +/- 0.3 microM, P <0.01). BSO and DEM produced a significant depletion in intracellular GSH levels (9.6 +/- 0.4 nmol 10(-6) cells, 17.9 +/- 1.0 nmol 10(-6) cells) compared with the controls (30.5 +/- 0.6 nmol 10(-6) cells). Intracellular DCF production in KU7 cells treated with CDDP (1.35 +/- 0.33 microM) was significantly enhanced by the addition of BSO (4.43 +/- 0.33 microM) or DEM (3.12 +/- 0.22 microM) at 150 min. These results suggest that ROS may play a substantial role in CDDP-induced cytotoxicity and that GSH depletors augment its cytotoxicity through an enhancement of ROS generation in bladder cancer cells.

Antimetabolites↗
PubMed1997

Molecular cloning of CISH, chromosome assignment to 3p21.3, and analysis of expression in fetal and adult tissues.

The murine cytokine inducible SH2-containing (Cis) protein gene (Cish) was recently cloned and shown to have a growth inhibitory function. We have isolated cDNAs coding for its human homologue (CISH) and assigned the gene to 3p21.3 by fluorescence in situ hybridization. Northern blot analysis showed CISH expression in various epithelial tissues including lung and kidney, in which tumors frequently exhibit 3p21.3 deletions.

Adult↗
PubMed1997

A transient increase in serum procollagen 1 carboxyterminal peptide following effective treatment in prostate cancer patients with bone metastases.

Procollagen 1 carboxyterminal peptide (P1CP) is thought to be an indicator of new bone formation. The present report demonstrates that effective endocrine therapy induced an initial increase followed by a delayed decrease in serum levels of P1CP and alkaline phosphatase in spite of an immediate decrease in serum PSA and PAP and improvement of clinical symptoms in prostate cancer patients with bone metastases. The transient increase in P1CP and alkaline phosphatase is a healing reaction and is followed by apparent improvement. Short-term effects of endocrine therapy on prostate cancer patients with bone metastases should be comprehensively evaluated based upon the entire spectrum of clinical and laboratory findings including serial changes of serum prostate markers and bone markers as well.

Adenocarcinoma↗
PubMed1997

ACTH-independent bilateral macronodular adrenocortical hyperplasia caused Cushing's syndrome.

A 53-year-old man who had been followed up for the treatment of hypertension presented with a bilateral adrenal mass during a screening CT scan. Other imaging studies and biochemical tests suggested Cushing's syndrome caused by a pituitary-independent and adrenal-dependent bilateral adrenal tumor. A total adrenalectomy was performed and the pathological appearance of the surgical specimen showed adrenal hyperplasia. Therefore, these findings were considered to be consistent with ACTH-independent bilateral macronodular adrenal hyperplasia (AIMAH). This tumor is quite rare and its etiology still remains controversial. We herein report this incidentally found AIMAH and also review the pertinent literature.

Adrenal Glands↗
PubMed1997

Clinical experience with incidentally discovered pheochromocytoma.

PURPOSE: We reviewed 17 resected pheochromocytomas comprising 7 from symptomatic patients, and 10 unsuspected and incidentally discovered tumors. We compared various parameters concerning these 2 groups and investigated the features of the incidentally discovered pheochromocytoma. MATERIALS AND METHODS: Patient gender and age, clinical symptoms and signs, tumor localization, detection methods, findings on imaging studies, urinary catecholamine concentrations, results of metoclopramide stimulation tests, treatments at operation and tumor size were evaluated. Furthermore, we compared the clinically diverse aspects arising between the symptomatic and incidentally discovered pheochromocytomas. RESULTS: The 24-hour urinary noradrenaline and vanillylmandelic acid levels in the incidental cases tended to be lower than those in the symptomatic cases, while 24-hour urinary dopamine was significantly less (468 +/- 221 compared to 1,558 +/- 899 microg./day, respectively). Typical symptoms of pheochromocytoma were noted in 6 patients (60%) in the incidental tumor group. The incidental cases had a markedly high false-negative rate (71%) as noted by the metoclopramide stimulation test, although the symptomatic cases had a 100% positive rate. On the other hand, the average diameter of incidental tumors was significantly larger than that of the symptomatic lesions (55.5 +/- 19.1 versus 35.9 +/- 12.1 mm., respectively). CONCLUSIONS: Clinical signs and findings in patients with incidental tumors were weaker than those with symptomatic disease although most incidental tumors functioned. Lower urinary catecholamine values in the incidental tumors were consistent with these results. However, the surgical risk for incidental tumors was the same as that for symptomatic lesions. Therefore, patients with incidentally discovered pheochromocytomas scheduled to undergo surgery should be treated accordingly.

Adolescent↗
PubMed1997

The value of serum carboxyterminal propeptide of type 1 procollagen in predicting bone metastases in prostate cancer.

PURPOSE: Carboxyterminal propeptide of type 1 procollagen (P1CP) is believed to be a marker of new bone formation. We investigated the possible application of serum P1CP as a biochemical marker for bone metastases in patients with prostate cancer. MATERIALS AND METHODS: Prostate specific antigen (PSA), prostatic acid phosphatase (PAP), P1CP and alkaline phosphatase were measured in 136 serum samples from 79 patients with untreated prostate cancer, 29 with stage D2 disease in remission and 28 with progressive stage D2 carcinoma. RESULTS: Serum P1CP and alkaline phosphatase were significantly elevated in untreated patients with a positive bone scan (278.9 +/- 61.9 ng./ml. and 826.5 +/- 176.3 international units per 1., respectively) compared to those with a negative bone scan (104.2 +/- 4.2 and 200.8 +/- 9.1, respectively, p <0.05). The areas under receiver operating characteristics curves were 0.86 for P1CP, 0.87 for alkaline phosphatase, 0.88 for PSA and 0.85 for PAP. The best accuracy rates for P1CP, alkaline phosphatase, PSA and PAP to predict bone lesions were 84, 87, 86 and 84%, respectively. P1CP provided a greater specificity and positive predictive value. These serum markers correlated significantly with the extent of disease on bone scan (p <0.05). The incidence of positive serum P1CP and alkaline phosphatase decreased significantly in response to endocrine therapy in patients with bone metastasis, and increased progressively in association with progression of the tumor (p <0.05) parallel to PSA and PAP. CONCLUSIONS: These findings suggest that serum P1CP is a useful indicator for predicting bone metastases.

Aged↗
PubMed1997

The role of erythropoietin receptor tyrosine phosphorylation in erythropoietin-induced proliferation.

Although studies with truncated erythropoietin receptors (EpoRs) have suggested the tyrosine phosphorylation (Yphos) of the EpoR may not play a significant role in Epo-induced proliferation, we found, using a full length EpoR mutant designed Null, in which all 8 of the intracellular tyrosines (Ys) were substituted with phenylalanines (Fs), that Null cells required 5-10 fold more Epo than wild type (WT) EpoR containing cells in order to proliferate as well. Moreover, a comparison of Epo-induced proliferation with Epo-induced Yphos patterns, using DA-3 cells expressing WT, Null and various Y to F EpoR point mutants revealed that Stat5 Yphos and activation correlated directly with proliferation and was mediated primarily throuhg the most membrane proximal Y, i.e., Y343, although other tyrosines (most likely Y401 and Y431) within the EpoR could activate Stat5 in its absence. We also found that EpoR Yphos was essential for the Yphos of Shc and for the Yphos and association of a 145 kDa protein with Shc. We purified and cloned this Shc-associated 145 kDa protein and found that it was a unique SH2 containing inositol polyphosphate-5-phosphatase. This novel enzyme, which we have called SHIP for SH2-containing inositol-phosphatase, may modulate both Ras and inositol signaling pathways.

Amino Acid Sequence↗
PubMed1997

Cloning and biological activity of murine oncostatin M.

Oncostatin M (OSM) is a member of the interleukin-6/leukemia inhibitory factor (LIF) family cytokines. While human OSM (hOSM) has been characterized, the murine counterpart had not been isolated. We cloned a murine OSM (mOSM) cDNA as a gene that is induced in hematopoietic cells by a subset of cytokines including IL-3, GM-CSF and Epo. Identity of mOSM was based on overall homology to hOSM and chromosomal gene localization. Human OSM is known to exhibit biological activities similar to LIF, because they share the same functional receptor composed of the LIF receptor and gp130. As compared to hOSM, however, a 1000-fold higher concentrations of mOSM was required to stimulate proliferation of LIF-dependent murine DA1a cells, differentiation of M1 macrophage cells, and inhibition of ES cell differentiation. On the other hand, mOSM inhibited growth of NIH3T3 cells at a 1000-fold lower concentration than that of hOSM. These results indicate that mOSM functions through a receptor which is distinct from that of the LIF receptor. Studies on the physiological role of OSM is underway.

3T3 Cells↗