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Biomedical subjects

S Nakashima

Publications and source records attributed to S Nakashima.

At least 37 records · Page 2Linked to original sources
PubMed2001

MDM2 enhances the function of estrogen receptor alpha in human breast cancer cells.

Overexpression of the oncoprotein MDM2, a negative feedback regulator of p53, is often observed in breast cancer tissue and cell lines, particularly in those which express estrogen receptor alpha (ERalpha). In this study, we report a novel function of MDM2, i.e., as a positive regulator of ERalpha. This function does not involve p53. MDM2 overexpressing clones derived from the breast cancer cell line, MCF-7 cells, showed a remarkable growth advantage only in estradiol supplemented conditions, and this profile coincided with increased transcriptional activity of ERalpha in these cells. Though p53 has been reported to be an inhibitor of ERalpha function, p53 protein in MDM2 overexpressing clones was more abundant than in the parental cells. When ERalpha was exogenously expressed in p53-null cells, its activity was enhanced by coexpression of MDM2. Mammalian two-hybrid assays and GST pull-down assays indicated that MDM2 could interact with ERalpha. These results indicate that MDM2 is a direct activator of ERalpha function, and suggest such a role for MDM2 in ERalpha-positive breast cancer.

Blotting, Western↗
PubMed2001

Possible involvement of reactive oxygen species in D-galactosamine-induced sensitization against tumor necrosis factor-alpha-induced hepatocyte apoptosis.

Intravenous administration of tumor necrosis factor-alpha (TNF-alpha) (0.5 microg/mouse) caused hepatocyte apoptosis in BALB/c mice when they were sensitized with D-galactosamine (GalN, 20 mg/mouse). Activation of nuclear factor kappa B (NF-kappa B) and expression of apoptotic Bcl-2 family members were not significantly different between livers of mice treated with TNF-alpha alone and GalN + TNF-alpha, indicating that neither activation of NF-kappa B nor expression of Bcl-2 family is involved in the sensitization by GalN against TNF-alpha-induced hepatocyte apoptosis. To identify differentially expressed genes implicated in GalN-induced hepatocyte sensitization, we adopted mRNA fingerprinting using an arbitrarily primed polymerase chain reaction. The present analysis revealed that mRNA expression of extracellular antioxidant, selenoprotein P, was up-regulated in the livers after GalN administration. GalN-induced increase in its protein level was confirmed by Western blotting. Increased expression of this gene was also observed in the liver of mice treated with concanavalin A, but not anti-Fas antibody. mRNA of another antioxidant, glutathione peroxidase-1, was also up-regulated, and lipid peroxides were produced in the liver after GalN administration. Selenoprotein P mRNA level also increased in Huh-7 human hepatoma cells incubated with GalN (5 or 10 mM). Accordingly, formation of reactive oxygen species (ROS) was observed in GalN-treated Huh-7 cells. H(2)O(2) induced up-regulation of selenoprotein P mRNA and sensitized Huh-7 cells to TNF-alpha-induced apoptosis. These results suggest that ROS produced by GalN may play a pivotal role in hepatocyte sensitization toward TNF-alpha-induced apoptosis.

Animals↗
PubMed2001

Detection and prediction of micrometastasis in the lymph nodes of patients with pN0 gastric cancer.

BACKGROUND: The clinicopathologic significance of micrometastasis (MM) and tumor cell microinvolvement (TCM) in regional lymph nodes as identified by immunohistochemical staining for cytokeratin expression was evaluated in patients with node-negative gastric cancer. METHODS: MM was defined as tumor cells with stromal reaction, and TCM was defined as individual tumor cells without stromal reaction. We investigated 1761 lymph nodes obtained from 67 gastric cancer patients whose diagnosis showed no lymph node metastasis by routine histological examination. The depth of tumor invasion was T1 (submucosa) in 33 patients and T2 (muscularis propria and subserosa) in 34 patients. The lymph nodes were examined immunohistochemically for the presence of tumor cells using anti-cytokeratin AE1/AE3 monoclonal antibody. Both the biopsy tumor specimens obtained prior to surgery and the resected primary tumors were immunostained with E-cadherin (E-cad) monoclonal antibody. RESULTS: Thirty (1.5%) of the 1761 lymph nodes showed MM and/or TCM. MM with or without TCM was found in 10 patients, and TCM alone was found in 4 patients; 6 (18.2%) of the 33 patients with T1 tumor and 8 (23.5%) of the 34 patients with T2 tumor had occult lymph node metastasis. The 5-year survival rate was worse among those with MM with or without TCM, than among those without MM. Nearly all of the patients with MM and/or TCM had reduced or negative E-cad expression in the primary tumor. CONCLUSIONS: We demonstrated that the incidence of MM and/or TCM in the lymph nodes of patients with gastric cancer is quite high, and that such metastasis is associated with the prognosis of patients with pN0. Examination of E-cad expression in biopsy tumor specimens may be useful for predicting MM and/or TCM.

Adult↗
PubMed2001

Clinical significance and prognostic value of apoptosis related proteins in superficial esophageal squamous cell carcinoma.

BACKGROUND: The purpose of the present study was to examine the expression of cell cycle regulators [p53, p21WAF1/CIP1 (p21), and Rb] and apoptosis related proteins Bax and Bcl-X(L) and to evaluate the relationship between their expressions and clinicopathological findings in patients with superficial squamous cell carcinomas of the esophagus. METHODS: We immunohistochemically investigated the expression of p53, p21, Rb, Bax, and Bcl-X(L) in 79 patients with superficial esophageal carcinoma. RESULTS: p21 overexpression was found in mucosal carcinoma (P = 0.05) and a high Bcl-X(L) score was observed for submucosal carcinoma (P = 0.03). The patients with high Bcl-X(L) score had more frequent lymphatic invasion and lymph node metastasis than did those with low Bcl-X(L) score (P < 0.05). Univariate analysis revealed significantly shorter survival in patients with high Bcl-X(L) expression than in those with low Bcl-X(L) expression, but Bcl-X(L) expression was not identified as an independent prognostic factor by multivariate analysis. CONCLUSIONS: Because Bcl-X(L) expression correlated well with depth of tumor invasion, lymphatic invasion, and lymph node metastasis, examination of Bcl-X(L) expression will help to estimate the properties in superficial squamous cell carcinoma of the esophagus.

Adult↗
PubMed2001

Role of ceramide during cisplatin-induced apoptosis in C6 glioma cells.

Cisplatin is commonly used for the treatment of malignant brain tumors. However, the mechanisms of cell death by cisplatin are not fully understood. Therefore, the present study was designed to elucidate the apoptotic signaling pathway(s) activated by cisplatin in a C6 rat glioma cell line. C6 cells were treated with various concentrations of cisplatin (0.2-10 microg/ml) for 24-72 h. At 10 microg/ml cisplatin, over 90% of the cells became dead at 72 h. Apoptotic death was confirmed by condensation and fragmentation of nuclei, and DNA laddering. Even in cells treated with 1.5 microg/ml cisplatin, typical apoptotic cells were observed at 72 h. The intracellular level of ceramide, measured Escherichia coli diacylglycerol kinase markedly increased during 24-72 h after the addition of 10 microg/ml cisplatin. The activity of caspase-3(-like) proteases increased and reached a peak at 48 h. Inhibitors of caspases reduced the number of apoptotic cells. Pretreatment of C6 cells with glutathione or N-acetyl-cysteine, which are known to block the activation of neutral magnesium-dependent sphingomyelinase, inhibited ceramide formation, leading to suppression of both activation of caspase-3(-like) proteases and apoptosis by cisplatin. In contrast, pretreatment of the cells with N-oleoylethanolamine (OE), a ceramidase inhibitor, potentiated apoptosis induced by cisplatin. Furthermore, OE enhanced sensitivity of the cisplatin-resistant cells to cisplatin. These results suggest that ceramide is closely implicated in apoptosis of glioma cells by cisplatin through activation of caspase-3(-like) proteases.

Acetylcysteine↗
PubMed2001

Caspase activation during hepatocyte apoptosis induced by tumor necrosis factor-alpha in galactosamine-sensitized mice.

BACKGROUND/AIMS: To clarify the mechanism of hepatocyte apoptosis induced by tumor necrosis factor-alpha (TNF-alpha), caspase cascade and ceramide formation were investigated in the liver of D-galactosamine (GalN)-sensitized mice treated with TNF-alpha. METHODS: Seven-week-old male BALB/c mice were intraperitoneally injected with 20 mg GalN 30 min prior to the intravenous injection of recombinant mouse TNF-alpha (0.5 microg/mouse). Cytochrome c release and processing of procaspases in the liver were analyzed by Western blotting. Activities of caspases were measured using chromogenic peptides as substrates. Ceramide content was determined using Escherichia coli diacylglycerol kinase. RESULTS: Apoptosis of hepatocytes was observed in mice treated with both GalN and TNF-alpha (GalN/TNF-alpha), but not GalN or TNF-alpha alone. Activation of caspases-9 and -3, and cytochrome c release were observed only in liver from mice treated with GalN/TNF-alpha. In a cell-free system, processing of procaspases-9 and -3, and cytochrome c release were observed in the postnuclear fraction of liver obtained from GalN/TNF-alpha-treated mice, but not in that from control mice. Processing of procaspase-3 was inhibited by a caspase-9 inhibitor, but not by inhibitor for caspase-8 or -2. In a reconstitution assay system, procaspase-9 processing occurred, when both cytosol and membrane fractions were obtained from the liver of mice treated with GalN/TNF-alpha. Ceramide accumulation was observed only in apoptotic liver and preceded cytochrome c release and caspase activation. CONCLUSION: Cytochrome c release and caspase-9 activation are required for the activation of executor caspase-3 in TNF-alpha-induced hepatocyte apoptosis, but caspases-8 and -2 play, if any, a minimal role. Ceramide may be implicated in this apoptotic process.

Animals↗
PubMed2001

Centriole behavior during meiosis in oocytes of the sea urchin Hemicentrotus pulcherrimus.

Ultrastructural changes in the maturing oocyte of the sea urchin Hemicentrotus pulcherrimus were observed, with special reference to the behavior of centrioles and chromosomes, using oocytes that had spontaneously started the maturation division process in vitro after dissection from ovaries. The proportion of oocytes entering the maturation process differed from batch to batch. In those eggs that accomplished the maturation division, it took ~4.5-5 h from the beginning of germinal vesicle breakdown to the formation of a second polar body. Serial sections revealed that a young oocyte before germinal vesicle breakdown had a pair of centrioles with procentrioles, located between the presumed animal pole and the germinal vesicle and accompanied by amorphous aggregates of moderately dense material and dense granules (granular aggregate). Just before germinal vesicle breakdown, a pair of fully grown centrioles located in the granular aggregate, which is present until this stage and then disappears, had already separated from another pair of centrioles. In meiosis I, each division pole had two centrioles, whereas in meiosis II each had only one. The two centrioles in the secondary oocyte separated into single units and formed the mitotic figure of meiosis II. The first polar body had two centrioles and the second had only one. The two centrioles in the first polar body did not form the mitotic figure nor did they separate at the time of meiosis II. These results indicate that, in sea urchins, duplication of the centrioles does not occur during the two successive meiotic divisions and the egg inherits only one centriole from the primary oocyte, confirming the results previously reported for starfish oocytes.

Animals↗
PubMed2001

Micrometastases in the cervical lymph nodes in esophageal squamous cell carcinoma.

Few studies have investigated the presence of lymph node micrometastases (MM) in the cervical region of patients with esophageal squamous cell cancer. The present study examines the presence of cervical MM and attempts to determine a way to predict the occurrence and site of such micrometastases. A total of 2203 cervical lymph nodes and 118 mediastinal recurrent nerve nodes obtained from 86 patients with esophageal carcinoma were examined immunohistochemically using cytokeratins. Cervical lymph nodes and mediastinal recurrent nerve nodes metastases were detected histologically in 33 and 41 of the 86 patients respectively. Cervical lymph node and mediastinal recurrent nerve node MM were immunohistochemically detected in 16 (18.6%) and 6 (7.0%) patients respectively. Of these 16 patients with cervical MM, seven were found to have lymph node metastases in different cervical regions, whereas cervical MM only were detected in nine patients. Among the former group of patients, five were diagnosed by ultrasound examination as having cervical lymph node metastases. Mediastinal recurrent nerve node metastases and MM correlated with the presence of cervical MM in all but one patient. Cervical lymph node metastasis, including micrometastasis, can be predicted by preoperative ultrasonography and the routine histologic examination of mediastinal recurrent nerve nodes.

Adult↗
PubMed2001

Crucial role of calpain in hypoxic PC12 cell death: calpain, but not caspases, mediates degradation of cytoskeletal proteins and protein kinase C-alpha and -delta.

Ca2+ influx is one of the main causative events in hypoxic PC12 cell death, because an extracellular Ca2+ chelator, ethylene glycol bis (2-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) inhibited and Ca2+ ionophore A23187 mimicked the hypoxic cell death. The hypoxic cell death was markedly prevented by a broad spectrum caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (z-VAD-FMK) as well as a calpain inhibitor, calpeptin, as assessed by nuclear staining with Hoechst 33258 and lactate dehydrogenase release. The processing of procaspase-3 was inhibited by z-VAD-FMK, but not by calpeptin. In contrast, z-VAD-FMK failed to block the proteolytic cleavage of fodrin-alpha, a preferential substrate for calpain. On the other hand, degradation of actin and fodrin-alpha was prevented by calpeptin but not by z-VAD-FMK. In addition, not only protein kinase C (PKC)-alpha but also PKC-delta were cleaved to generate approximately 46 kDa fragments. The PKC fragmentation was inhibited by calpeptin but not by z-VAD-FMK. These findings suggest that the extracellular Ca2+ influx induced by hypoxic stress activates calpain, resulting in the degradation of cytoskeletal proteins and generation of PKC fragments almost independently of caspase activation. Therefore, calpain may play an important role in hypoxic PC12 cell death.

Animals↗
PubMed2001

[A case of aneurysm of the peripheral middle cerebral artery undetectable on preoperative angiogram].

The authors describe a rare case of an aneurysm of the peripheral middle cerebral artery. A 63-year-old female with a past history of hypertension suddenly fell into a comatose state, and was brought to our hospital. On admission, CT scan showed intracerebral hematoma located in the right putamen with diffuse subarachnoid hemorrhage. To exclude vascular lesions, an angiography was performed just after admission. The right carotid angiogram showed an aneurysm at the cavernous portion of the internal carotid artery (ICA), but failed to show any aneurysms in the rest of the intracranial circulation. Just after the angiography, emergent operation was performed for the main purpose of evacuation of the hematoma, and with only the secondary purpose of searching for undetectable aneurysms. The patient underwent a right frontotemporal craniotomy. After partial evacuation of the hematoma through the corticotomy of the right frontal operculum, the Sylvian fissure was opened widely. No aneurysm was observed either in the main trunk of the right ICA or the middle cerebral artery (MCA). During the final stage of evacuation of the hematoma through the corticotomy, arterial bleeding occurred. While evacuating the blood, we detected a saccular aneurysm arising from MCA branch (M2-M3 junction) and we clipped the aneurysm. We discuss peripheral MCA aneurysms with a review of the literature.

Cerebral Angiography↗
PubMed2001

[Multiple brain abscesses associated with Rendu-Osler-Weber disease: report of two cases].

Two cases of multiple brain abscesses associated with congenital pulmonary arteriovenous fistula are reported. A 57-year-old male with Rendu-Osler-Weber disease complicated by pulmonary arteriovenous fistula developed multiple brain abscesses in the right parietal region. He responded well to surgical drainage and antibiotic therapy, and the pulmonary arteriovenous fistula, located in the left lower lobe, was resected. A 26-year-old female with Rendu-Osler-Weber disease complicated by pulmonary arterivenous fistula developed recurrent multiple brain abscesses in both the frontal and right parietal regions. The brain abscesses were successfully treated with aspiration and antibiotic therapy. She had a history of two previous brain abscesses in the right parietal regions that were excised on separate occasions at 16 and 23 years of age. Although pulmonary arteriovenous fistula was confirmed by angiography, in this case surgical removal of the pulmonary lesions was not indicated due to multiple vascular shunting. The patient had no recurrence of brain abscess with oral antibiotic therapy.

Adult↗
PubMed2001

[Intracranial occlusion of the internal carotid artery after minor closed head injury].

Thrombosis of the extracranial portion of the internal carotid artery as a result of nonpenetrating head and neck injury is not uncommon. However, intracranial occlusion of the internal carotid artery after minor head and neck injury without skull fracture is rare. We report a case of 14-year-old male who suffered a minor head injury during an athletic meeting of his school and developed a right hemiparesis and a lethargy state resulting from thrombosis of the supraclinoid portion of the left internal carotid artery. On admission, skull films and a CT scan revealed no abnormality. One hour later, he fully recovered. One day later, no definite lesions were detected on T1-weighted and T2-weighted image of MRI, but an abnormal high signal lesion in the left frontal lobe was detected on diffusion-weighted image of MRI. On additional MR angiography, intracranial occlusion of the internal carotid artery due to dissection was demonstrated.

Adolescent↗
PubMed2000

Regiochemistry in aryl radical cyclization onto methylenecycloalkanes

Bu(3)SnH-mediated aryl radical cyclization onto methylenecycloalkanes having a phenylthio, an ester, or a nitrile group at the terminus of the alkenic bond provides exclusively exo cyclization products. The results are in sharp contrast to those reported for nonsubstituted methylenecycloalkanes, which give exclusively endo cyclization products. Formation of endo cyclization products has been suggested to be a result of a consecutive 5-exo cyclization of an aryl radical and neophyl rearrangement. The exo-selective aryl radical cyclization offers a new method for synthesizing fused aromatic compounds containing a benzylic quaternary carbon atom.

Journal Article↗
PubMed2000

Increased phospholipase D2 activity during hypoxia-induced death of PC12 cells: its possible anti-apoptotic role.

During hypoxic incubation (1% O2) of PC12 cells, the PLD activity was transiently increased within 12h, followed by a gradual decrease. In the in vitro assay, the increased PLD activity was independent of GTPgammaS required for PLD1 or of oleic acid for PLD(OA), suggesting the activation of PLD2. The level of PLD2 protein showed no change up to 12h but a gradual decrease after 24 h. Pretreatment of cells with S. chromofuscus PLD resulted in inhibition of hypoxia-induced apoptotic cell death. In contrast, 1-butanol, but not 2-butanol, potentiated cell death. Moreover, the number of apoptotic cells significantly reduced in PC12 cells over-expressing PLD2. These results raise the possibility that PLD2 activation may play an anti-apoptotic role in hypoxia-induced cell death.

1-Butanol↗
PubMed2000

Effect of neoadjuvant chemotherapy for lymph node micrometastasis and tumor cell microinvolvement in the patients with esophageal carcinoma.

Micrometastasis (MM) and tumor cell microinvolvement (TCM) in the lymph node were immunohistochemically evaluated using the cytokeratin (CK) antibody between a surgery group (n=20; 929 lymph nodes) and a chemotherapy group (n=20; 1052 lymph nodes). The incidence of MM+/-TCM in the surgery and chemotherapy groups was 50.0 (10/20) and 55.0% (11/20), respectively. Limiting the analysis to TCM alone revealed that the incidence in the chemotherapy group (10.0%; 2/20) was significantly lower than that in the surgery group (40.0%; 8/20; P=0.032). Preoperative chemotherapy in this regime was not effective, except for some patients with TCM alone.

Aged↗
PubMed2000

Apoptosis and cell proliferation in esophageal sqamous cell carcinoma treated by chemotherapy.

The p53 gene is associated with G1 arrest during the cell cycle and with apoptosis. To evaluate the preoperative chemotherapeutic effect in esophageal squamous cell carcinoma, we retrospectively investigated the apoptotic index (AI) and Ki-67 labeling index (Ki-67LI) in relation to the expression of p53. Thirty patients with esophageal carcinoma who had received chemotherapy prior to surgery were examined using the terminal deoxynucleotidyl-transferase-mediated in-situ end-labeling (TUNEL) method for evaluating AI and immunohistochemical staining with anti Ki-67 and anti p53 antibody for evaluating Ki-67LI and p53 expression, respectively. The histological response rate of chemotherapy was 20.0%. A significant correlation between p53-negative expression and response to chemotherapy was found (P<0. 01). The AIs and Ki-67LIs in p53-negative tumors with ineffective responses to chemotherapy were significantly higher than those in p53-positive tumors with ineffective responses (P<0.05). The AIs and Ki-67LIs were significantly lower in p53-negative tumors with effective responses to chemotherapy than those in p53-negative tumors with ineffective responses (P<0.05 and P<0.01, respectively). Furthermore, significant correlations were found between AIs and Ki-67LIs in p53 negative tumors (r=0.60, P<0.05). In esophageal carcinoma, p53-negative tumors with highly proliferative cells might be susceptible to apoptosis induced by chemotherapy.

Adult↗
PubMed2000

Influence of Bax or Bcl-2 overexpression on the ceramide-dependent apoptotic pathway in glioma cells.

Ceramide has recently been regarded as a potential mediator of apoptosis. In the present study, the effects of Bcl-2 and Bax on the ceramide-mediated apoptotic pathways were examined in glioma cells overexpressing Bcl-2 or Bax. Etoposide, cisplatin and tumor necrosis factor-alpha induced apoptosis of C6 rat glioma cells which was associated with ceramide formation due to activation of neutral sphingomyelinase, followed by release of mitochondrial cytochrome c into the cytosol and activation of caspases-9 and -3. The growth of C6 cells stably overexpressing either Bcl-2 or Bax was almost equal to that of the vector-transfected cells. Bax overexpression enhanced etoposide-induced apoptosis through acceleration of cytochrome c release and caspases activation. However, Bax had no effect on ceramide formation. Similar findings were obtained in C6 cells and U87-MG human glioblastoma cells which were transiently overexpressed with Bax. In contrast, Bcl-2 overexpression resulted in a retardation of the apoptotic process via prevention of cytochrome c release and caspases activation, and ceramide formation was also blocked when Bcl-2 was highly overexpressed in glioma cells. In addition, transient overexpression of Bcl-xL also exerted inhibitory effects on ceramide formation and apoptotic cell death induced by etoposide. These results indicate that Bax promotes apoptosis regardless of ceramide formation and that Bcl-2 or Bcl-xL prevents ceramide formation by repressing neutral sphingomyelinase as well as ceramide-induced cytochrome c release. Oncogene (2000) 19, 3508 - 3520

Animals↗