Biomedical subjects

S Kitajima

Publications and source records attributed to S Kitajima.

At least 19 recordsLinked to original sources

PubMed2006

Induction of apoptosis and cellular senescence in mice lacking transcription elongation factor, Elongin A.

Elongin A is a transcription elongation factor that increases the overall rate of mRNA chain elongation by RNA polymerase II. To gain more insight into the physiological functions of Elongin A, we generated Elongin A-deficient mice. Elongin A homozygous mutant (Elongin A(-/-)) embryos demonstrated a severely retarded development and died at between days 10.5 and 12.5 of gestation, most likely due to extensive apoptosis. Moreover, mouse embryonic fibroblasts (MEFs) derived from Elongin A(-/-) embryos exhibited not only increased apoptosis but also senescence-like growth defects accompanied by the activation of p38 MAPK and p53. Knockdown of Elongin A in MEFs by RNA interference also dramatically induced the senescent phenotype. A study using inhibitors of p38 MAPK and p53 and the generation of Elongin A-deficient mice with p53-null background suggests that both the p38 MAPK and p53 pathways are responsible for the induction of senescence-like phenotypes, whereas additional signaling pathways appear to be involved in the mediation of apoptosis in Elongin A(-/-) cells. Taken together, our results suggest that Elongin A is required for the transcription of genes essential for early embryonic development and downregulation of its activity is tightly associated with cellular senescence.

Animals↗

PubMed2006

Periostin is frequently overexpressed and enhances invasion and angiogenesis in oral cancer.

Oral squamous-cell carcinoma (OSCC) is one of the most common types of human cancer. Typically OSCC cells show persistent invasion that frequently leads to local recurrence and distant lymphatic metastasis. We previously identified Periostin as the gene demonstrating the highest fold change expression in the invasive clone by comparing the transcriptional profile of parent OSCC cell line and a highly invasive clone. Here, we demonstrated that Periostin overexpression enhanced invasiveness in oral cancer cell lines. To know the role of Periostin in invasion, angiogenesis and metastasis in OSCC cases, we first examined the expression of Periostin mRNA in 31 OSCC cases by RT-PCR and Periostin protein in 74 OSCC cases by immunohistochemistry. Then, we compared the Periostin expression with invasion pattern, metastasis and blood vessel density. Periostin mRNA and protein overexpression were frequently found in OSCC cases and Periostin expression was well correlated with the invasion pattern and metastasis. Moreover, blood vessel density of Periostin-positive cases was higher than those of Periostin-negative cases. Interestingly, recombinant Periostin enhanced capillary formation in vitro in a concentration-dependant manner. In summary, these findings suggest that Periostin may promote invasion and angiogenesis in OSCC, and that Periostin can be a strong marker for prediction of metastasis in oral cancer patients.

Biomarkers, Tumor↗

PubMed2005

Elevated macrophage migration inhibitory factor (MIF) levels in the urine of patients with focal glomerular sclerosis.

The pathogenesis of focal glomerular sclerosis (FGS) is poorly understood. Macrophage migration inhibitory factor (MIF) is a potent pro-inflammatory cytokine released from T cells and macrophages, and is a key molecule in inflammation. To examine further the possible role of MIF in FGS, we measured MIF levels in the urine. The purpose of the present study was to evaluate the involvement of MIF in FGS. Urine samples were obtained from 20 FGS patients. The disease controls included 40 patients with minimal-change nephrotic syndrome (MCNS) and membranous nephropathy (MN). A group of healthy subjects also served as controls. Biopsies were performed in all patients prior to entry to the study. The samples were assayed for MIF protein by a sandwich enzyme-linked immunosorbent assay (ELISA). The levels of MIF in the urine of FGS patients were significantly higher than those of the normal controls and patients with MCNS and MN. In contrast, the levels of urinary MIF (uMIF) in patients with MCNS and MN did not differ significantly from normal values. In the present study, attention also focused on the relationship between uMIF levels and pathological features. Among the patients with FGS, uMIF levels were significantly correlated with the grade of mesangial matrix increase and that of interstitial fibrosis. There was also a significant correlation between uMIF levels and the number of both intraglomerular and interstitial macrophages. Although the underlying mechanisms remain to be determined, our study presents evidence that urinary excretion of MIF is increased in FGS patients with active renal lesions.

Adult↗

PubMed2004

Ruptured aneurysm at a duplicated middle cerebral artery with accessory middle cerebral artery.

Although many cerebral vascular anomalies are widely recognized, others are less well known or unclassified. Accessory middle cerebral artery (MCA) and duplicated MCA are among uncommon anomalies. We present a very rare case of subarachnoid haemorrhage due to rupture of a saccular aneurysm arising from a duplicated middle cerebral artery which was associated with an accessory middle cerebral artery.

Aneurysm, Ruptured↗

PubMed2004

Overexpression of lipoprotein lipase improves insulin resistance induced by a high-fat diet in transgenic rabbits.

AIMS/HYPOTHESIS: Dysfunctions of lipoprotein lipase (LPL) have been found to be associated with dyslipidaemias, atherosclerosis, obesity and insulin resistance. There are two conflicting hypotheses regarding the roles of LPL in glucose metabolism and insulin resistance. Whether systemically increased LPL activity would be beneficial or detrimental to insulin sensitivity is yet to be resolved. To address this issue, we studied transgenic rabbits overexpressing human LPL transgene. METHODS: LPL transgenic and control rabbits were fed a 10% high-fat diet (HFD) for 16 weeks. To evaluate glucose metabolism, we compared plasma levels of glucose and insulin in transgenic rabbits with control rabbits and performed an intravenous glucose tolerance test. In addition, we measured adipose tissue accumulation in HFD-fed rabbits. RESULTS: Increased LPL activity in transgenic rabbits resulted in a significant reduction of plasma triglycerides and non-esterified fatty acids, but not in basal levels of glucose and insulin. HFD feeding induced an elevation of plasma glucose levels accompanied by hyperinsulinaemia in control rabbits, but was significantly inhibited in transgenic rabbits. The intravenous glucose tolerance test showed that transgenic rabbits had faster glucose clearance associated with lower levels of insulin secretion than control rabbits. In addition, there was a significant reduction of body adipose tissue in transgenic rabbits compared with in control rabbits fed an HFD. Scanning electron microscopic examination revealed that adipocytes in transgenic rabbits were predominately small cells. CONCLUSIONS/INTERPRETATION: Our results showed that systemically increased LPL activity improves insulin resistance and reduces adipose accumulation in transgenic rabbits, indicating that systemic elevation of LPL may have potential benefits for the treatment of insulin resistance and obesity.

Adipocytes↗

PubMed2004

Antimonocyte chemoattractant protein-1 gene therapy reduces experimental in-stent restenosis in hypercholesterolemic rabbits and monkeys.

In-stent restenosis results exclusively from neointimal hyperplasia due to mechanical injury and a foreign body response to the prosthesis. Inflammation mediated by monocyte chemoattractant protein-1 (MCP-1) might therefore underlie in-stent restenosis. We recently devised a new strategy for anti-MCP-1 gene therapy by transfecting an N-terminal deletion mutant of the MCP-1 gene into skeletal muscles. We used this strategy to investigate the role of MCP-1 in experimental in-stent restenosis in hypercholesterolemic rabbits and monkeys. Transfection of the mutant MCP-1 gene suppressed monocyte infiltration/activation in the stented arterial wall and markedly reduced the development of neointimal hyperplasia. This strategy also suppressed local expression of MCP-1 and inflammatory cytokines. Therefore, inhibition of MCP-1-mediated inflammation is effective in reducing experimental in-stent restenosis. This strategy might be a useful form of gene therapy against human in-stent restenosis.

Animals↗

PubMed2004

Combined status of MUC1 mucin and surfactant apoprotein A expression can predict the outcome of patients with small-size lung adenocarcinoma.

AIM: Lung cancer is still a disease of high mortality, despite advanced diagnostic techniques. Here, we aim to report a unique method to predict the recurrence and outcome of patients with pulmonary adenocarcinomas. METHODS AND RESULTS: Immunohistochemical expression of MUC1 mucin and surfactant apoprotein A (SP-A) was examined in 185 cases of surgically removed lung adenocarcinomas of non-bronchioloalveolar type smaller than 30 mm. Staining results were evaluated semiquantitatively, and the expression of MUC1 and SP-A was compared in each case. There were 140/185 (76%) cases showing MUC1 expression higher than SP-A expression (MUC1>SP-A), and 45/185 (24%) cases showing MUC1 expression lower than or equal to SP-A expression (MUC1 SP-A pattern, but in 7% (3/45) of the patients with a MUC1< or =SP-A pattern after the median observation period of 41 months (1-99 months) (P < 0.01). The MUC1>SP-A group showed higher recurrence and worse survival than the MUC1<or =SP-A group by Kaplan-Meier's method (P < 0.01 and P < 0.005). Even in the patients with apparently favourable prognostic factors (well-differentiated adenocarcinoma or no lymph node metastasis), recurrence and survival were different between the two groups. CONCLUSIONS: A high MUC1/SP-A ratio is strongly associated with a poor outcome in patients with small-size lung adenocarcinoma.

Adenocarcinoma↗

PubMed2004

Blue light inhibits melanin synthesis in B16 melanoma 4A5 cells and skin pigmentation induced by ultraviolet B in guinea-pigs.

BACKGROUND: Little has been known about the effects of visible light in mammalian cells. We recently found that blue light not only suppressed the growth of B16 melanoma cells in a time-dependent manner but also inhibited metastasis of the B16 melanoma cells to the lung. These findings suggest that exposure to blue light modifies the functions of B16 melanoma cells. The present study investigated the effects of blue light on B16 melanoma 4A5 cells and Weiser-Maple guinea-pigs to confirm the biological effect of blue light on melanin formation. METHODS: The effect of red, green, and blue light on melanin synthesis in B16 melanoma 4A5 cells was measured. The back skin of brown Weiser-Maple guinea-pigs was exposed to ultraviolet B (UVB; 588 mJ/cm(2) (0.7 mW/cm(2)x 14 min) three times a week for 2 weeks to induce melanin deposition. Thirty minutes after each UVB exposure, blue light was applied for 30 min. Pigmentation of the exposed areas of skin was checked once a week, and photographs of the skin were taken by digital camera. Observation was continued for 18 days after the final UVB exposure. RESULTS: Melanin synthesis in B16 melanoma 4A5 cells was selectively suppressed by blue light, but blue light did not induce decolorization of previously produced melanin. In the back skin of brown guinea-pigs, the brightness of the sites exposed to UVB began to decrease on the fifth day of the experiment, decreasing further from the 12th day to the 18th day after UVB exposure. The brightness of the sites exposed to UVB and blue light decreased in a manner similar during the UVB exposure, but remained relatively unchanged from the 12th day to the 30th day. CONCLUSIONS: These results suggest that blue light suppresses melanin formation following repeated UVB exposure. Further investigation with various light such as blue light may lead to a new approach to the care of ultraviolet-affected skin such as hyperpigmentation.

Animals↗

PubMed2004

Mucin expression in pleomorphic adenoma of salivary gland: a potential role for MUC1 as a marker to predict recurrence.

BACKGROUND: Pleomorphic adenoma of the salivary gland (PA) is essentially a benign neoplasm. However, patients with recurrent PA are difficult to manage. There are rare reports on useful immunohistochemical markers to detect a high risk of recurrence when the primary lesions are resected. AIMS: To find a new marker to predict the recurrence of PA. METHODS: Primary lesions of PA were collected from nine patients showing subsequent recurrence and from 40 patients without recurrence during at least 10 years of follow up of the disease. Paraffin wax embedded tumour samples of the two groups were examined for the expression profiles of MUC1 (differentially glycosylated forms), MUC2, MUC4, MUC5AC, and MUC6 using immunohistochemistry. Several clinicopathological factors were also examined. RESULTS: In univariate analysis of the factors examined, MUC1/DF3 high expression (more than 30% of the neoplastic cells stained) in the primary lesions was seen more frequently in patients with recurrence (four of nine) than in those without recurrence (three of 40; p = 0.011). Larger tumour size (more than 3.0 cm) of the primary PA was also a significant (p = 0.035) risk factor for the recurrence of PA. In multivariate analysis, only high expression of MUC1/DF3 was found to be a significant independent risk factor for the recurrence of PA (p = 0.021). CONCLUSIONS: Expression of MUC1/DF3 in PA is a useful marker to predict its recurrence. Those patients with PA showing positive MUC1/DF3 expression should be followed up carefully.

Adenoma, Pleomorphic↗

PubMed2003

Expression of mucins (MUC1, MUC2, MUC5AC and MUC6) in mucinous carcinoma of the breast: comparison with invasive ductal carcinoma.

AIMS: Mucinous carcinoma of the breast usually shows less frequent lymph node metastasis and more favourable outcome compared with invasive ductal carcinoma. The aim of this study is to compare the expression profiles of several mucins in mucinous carcinomas and invasive ductal carcinomas to gain insight into the relationship between the less aggressive biological nature of mucinous carcinoma and the role of mucins. METHODS AND RESULTS: We examined the expression profiles of MUC1 (membrane-bound mucin) of different glycoforms (from non-glycosylated form to fully glycosylated form), MUC2 (intestinal type secretory mucin), MUC5AC (gastric surface type secretory mucin) and MUC6 (gastric pyloric gland type secretory mucin) in 17 mucinous carcinomas and 46 invasive ductal carcinomas using immunohistochemistry. Various glycoforms of MUC1 were expressed frequently in both mucinous carcinomas (65-100%) and invasive ductal carcinomas (92-100%), although non-glycosylated MUC1 (MUC1/CORE) and fully glycosylated MUC1 (MUC1/HMFG-1) showed significantly lower expression rates in mucinous carcinomas compared with those in invasive ductal carcinomas. The expression rates of MUC2 (94%) and MUC6 (71%) in mucinous carcinomas were significantly higher than those of MUC2 (15%) and MUC6 (15%) in invasive ductal carcinomas. There was no significant difference in the expression rate of MUC5AC in mucinous carcinomas (12%) and that in invasive ductal carcinomas (4%). CONCLUSIONS: The expression rate of MUC1/CORE and MUC1/HMFG-1, which is related to poor prognosis in the gastric and colorectal cancers, is low in mucinous carcinomas. The high expression rate of gel-forming secretory mucins (MUC2 and MUC6) in mucinous carcinoma suggests that high production of these types of mucins may act as a barrier to cancerous extension resulting in their less aggressive biological behaviour.

Adenocarcinoma, Mucinous↗

PubMed2001

Activation of JNK and transcriptional repressor ATF3/LRF1 through the IRE1/TRAF2 pathway is implicated in human vascular endothelial cell death by homocysteine.

Endothelial cell injury underlies an increased occurrence of thromboembolic vascular disease in hereditary hyperhomocysteinemia. We have previously shown that homocysteine causes activation of c-Jun NH(2)-terminal kinase (JNK) and activating transcription factor 3/liver regenerating factor 1 (ATF3/LRF1) and induces apoptosis in human umbilical vein endothelial cells (HUVECs). In this study, the activation of JNK and ATF3 in HUVECs was mediated by the endoplasmic reticulum (ER) resident transmembrane kinase IRE1alpha and beta, which sense and transduce signal of the accumulationj of unfolded proteins in the ER. Moreover, dominant negative mutants of tumor necrosis factor receptor-associated factor 2 and mitogen-activated kinase kinase 4 and 7, as well as antisense ATF3 cDNA, inhibited cell death by homocysteine. These results indicate that the activation of JNK and ATF3 through the ER stress of homocysteine plays a role in the homocysteine-induced cell death. The JNK-ATF3 pathway may be implicated in endothelial cell injury associated with hereditary hyperhomocysteinemia.

Activating Transcription Factor 3↗

PubMed2001

High expression of S-phase kinase-interacting protein 2, human F-box protein, correlates with poor prognosis in oral squamous cell carcinomas.

Reduced expression of p27(Kip1), a cyclin-dependent kinase (Cdk) inhibitor, is frequently found in various cancers, including oral squamous cell carcinoma (OSCC), and is attributable to an enhancement of its degradation. Skp2, an F-box protein necessary for DNA replication, is required for the ubiquitinylation and subsequent degradation of p27(Kip1). In the present study, we examined the expression of Skp2 and its correlation with the expression of p27(Kip1) protein or p27(Kip1) degradation in OSCC. Using immunohistochemistry, we found that high expression of Skp2 was present in 49% of OSCCs and only 20% of epithelial dysplasias. Significantly, high expression of Skp2 was correlated with poor prognosis of OSCC patients. We also found an inverse correlation between the expression of Skp2 and p27 by immunohistochemical analysis. A similar correlation was observed in OSCC cell lines and OSCC tissues by Western blot analysis. Interestingly, OSCC tissues with Skp2 expression had high p27(Kip1) degradation activity. These findings indicate that (a) Skp2 may play an important role for the development of OSCC, (b) Skp2 can be a novel target for OSCC treatment as well as a strong prognostic marker, and (c) the reduction in p27(Kip1) protein may be brought about by enhancement of its degradation mediated by increased levels of Skp2 protein.

Adult↗

PubMed2001

Homocysteine induces programmed cell death in human vascular endothelial cells through activation of the unfolded protein response.

Severe hyperhomocysteinemia is associated with endothelial cell injury that may contribute to an increased incidence of thromboembolic disease. In this study, homocysteine induced programmed cell death in human umbilical vein endothelial cells as measured by TdT-mediated dUTP nick end labeling assay, DNA ladder formation, induction of caspase 3-like activity, and cleavage of procaspase 3. Homocysteine-induced cell death was specific to homocysteine, was not mediated by oxidative stress, and was mimicked by inducers of the unfolded protein response (UPR), a signal transduction pathway activated by the accumulation of unfolded proteins in the lumen of the endoplasmic reticulum. Dominant negative forms of the endoplasmic reticulum-resident protein kinases IRE1alpha and -beta, which function as signal transducers of the UPR, prevented the activation of glucose-regulated protein 78/immunoglobulin chain-binding protein and C/EBP homologous protein/growth arrest and DNA damage-inducible protein 153 in response to homocysteine. Furthermore, overexpression of the point mutants of IRE1 with defective RNase more effectively suppressed the cell death than the kinase-defective mutant. These results indicate that homocysteine induces apoptosis in human umbilical vein endothelial cells by activation of the UPR and is signaled through IRE1. The studies implicate that the UPR may cause endothelial cell injury associated with severe hyperhomocysteinemia.

Apoptosis↗

PubMed2001

Transcriptional regulation of Mesp1 and Mesp2 genes: differential usage of enhancers during development.

Mesp1 and Mesp2 encode bHLH-type transcription factors, Mesp1 and Mesp2, respectively. The expression of both genes is observed in the nascent mesoderm, and subsequently in the rostral presomitic mesoderm. To determine the regulatory mechanism for gene expression, we attempted to identify enhancer elements by transient transgenic analysis. At least two enhancers, which are responsible for the expression of the two genes in the early mesoderm (early mesodermal enhancer, EME) and the presomitic mesoderm (PSM enhancer, PSME), and one suppressor, which is responsible for the rostrally restricted expression in the presomitic mesoderm, were identified. Deletion studies of these enhancer elements indicate that either gene may use the same enhancer for early mesoderm development, whereas both genes may utilize separate enhancers to regulate their expression in the presomitic mesoderm.

Animals↗

PubMed2001

A case of non-functioning pituitary adenoma with Cushing's syndrome upon recurrence.

A 49-year-old woman presented with left visual disturbance. No signs of Cushing's disease were evident. Basal levels of serum cortisol and plasma adrenocorticotropic hormone (ACTH) were 16.8 microg/dL and 66.0 pg/mL, respectively. MRI demonstrated an irregularly shaped large pituitary tumor, and the patient then underwent transsphenoidal surgery. By light microscopy the tumor represented a chromophobic adenoma with a few of the adenoma cells showing immunoreactivity for ACTH. On the basis of clinical and light microscopic examinations, the diagnosis of silent corticotroph adenoma was made. Electron microscopy, however, demonstrated the honeycomb Golgi complex that has been reported as a typical finding of gonadotroph adenomas. MRI taken 7 months after the first operation revealed adenoma regrowth. Transcranial surgery was performed, and histology demonstrated a chromophobic pituitary adenoma with most cells immunopositive for ACTH. She was treated with gamma knife postoperatively. Three months later, MRI revealed remarkable shrinkage of the adenoma, but she developed typical signs and symptoms of Cushing's disease. Thus, the hormone immunostaining and biological activity of pituitary adenomas may change with time.

Adrenocorticotropic Hormone↗

PubMed2001

Influence of organ site and tumor cell type on MUC1-specific tumor immunity.

We investigated the influence of organ-specific parameters on tolerance and immunity to human MUC1. C57Bl/6 mice (wild-type) and C57Bl/6 transgenic for MUC1 (MUC1.Tg) were challenged in the pancreas with Panc02-MUC1, a C57Bl/6-syngeneic pancreatic cancer cell line expressing human MUC1. Wild-type mice produced immune responses to MUC1 when presented on tumor cells growing in the pancreas; however, the responses to tumors in the pancreas were less effective than responses produced by tumor challenge at the s.c. site. Tumor immunity specific for MUC1 was produced in wild-type mice by two different procedures: (i) s.c. immunization of wild-type mice with a low dose of Panc02-MUC1 or (ii) adoptive transfer of spleen and lymph node cells harvested from wild-type mice previously immunized s.c. with Panc02-MUC1. This demonstrates that immune responses to MUC1 presented at the s.c. site can be detected and adoptively transferred. MUC1.Tg mice were immunologically tolerant to MUC1; however, some immunological protection against orthotopic challenge with Panc02-MUC1 was conferred by adoptive transfer of CD4+ and CD8+ T cells from wild-type mice. These results show that it is more difficult to produce immune responses to tumors growing at the pancreatic site than the s.c. site. Panc02-MUC1 cells growing in the pancreas were accessible to the immune system, and immune responses evoked by s.c. presentation of this molecule in wild-type mice were effective in rejecting tumor cells in the pancreas of both wild-type and MUC1.Tg mice. No effective anti-tumor immune responses against MUC1 were produced in MUC1.Tg mice.

Adoptive Transfer↗

PubMed2001

Characterization of ascorbate peroxidases from unicellular red alga Galdieria partita.

Galdieria partita, a unicellular red alga isolated from acidic hot springs and tolerant to sulfur dioxide, has at least two ascorbate peroxidase (APX) isozymes. This was the first report to demonstrate that two isozymes of APX are found in algal cells. Two isozymes were separated from each other at the hydrophobic chromatography step of purification and named APX-A and APX-B after the elution order in the chromatography. APX-B accounted for 85% of the total activity. Both isozymes were purified. APXs from Galdieria were monomers whose molecular weights were about 28,000, similar to stromal APX of higher plants. APX-A cross-reacted with monoclonal antibody raised against APX of Euglena gracilis in immunoblotting, but APX-B did not, although the antibody can recognize all other APXs tested. The amino-terminal sequences of APX-A and -B from Galdieria had some homology with each other but little homology with those from other sources. Their Km values for ascorbate and hydrogen peroxide were comparable with those of APX from higher plants. Unlike the green algal enzymes, the donor specificities of Galdieria APXs were as high as those of plant chloroplastic APX. On the contrary, these APXs reduced tertiary-butyl hydroperoxide as an electron acceptor as APXs from Euglena and freshwater Chlamydomonas do. The inhibition of APX-A and -B by cyanide and azide, and characteristics of their light absorbance spectra indicated that they were heme peroxidases.

Amino Acid Sequence↗

PubMed2001

Expression of PR-5d and ERF genes in cultured tobacco cells and their NaCl stress-response.

The expression of pathogenesis-related protein-5d (PR-5d) and ethylene-responsive transcriptional factors (ERF1-4) for basic PR-proteins was measured in cultured tobacco cells. The PR-5d transcript markedly increased with culture, but only constant levels of transcripts of ERF1 (trans-activator) and ERF3 (repressor) were detected in cells. These different responses of PR-5d and ERF genes were also observed under NaCl stress; PR-5d transcript decreased and ERF levels were constant under NaCl stress. The effect of post-transcriptional regulation of ERF activity, especially ERF3, on the expression of basic PR genes including PR-5d is discussed.

Cells, Cultured↗