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N Shinomiya

Publications and source records attributed to N Shinomiya.

At least 19 recordsLinked to original sources
PubMed2006

Multiple interleukin-18 injections promote both mouse Th1 and Th2 responses after sublethal Escherichia coli infection.

Interleukin (IL)-18 is considered to induce exclusively the Th1 immune response but not the Th2 response in the presence of adequate IL-12 stimulation in bacterial infections. However, we demonstrate herein that multiple IL-18 injections to the mice not only enhance the early Th1 response but also stimulate the Th2 response later after viable Escherichia coli infection. Multiple IL-18 injections (three alternate-day injections) raised the serum interferon (IFN)-gamma level at 6 h and serum Th2 cytokine levels, such as IL-4, IL-10 and IL-13, at 48 h after infection, while a single IL-18 injection increased only the serum IFN-gamma level. Depletion of mouse CD4+ cells suppressed the IL-18-induced Th2 cytokines, IL-4, IL-10 and IL-13. In contrast, depletion of natural killer (NK)1.1+ cells reduced the IFN-gamma and IL-13 levels. Moreover, multiple IL-18 injections up-regulated the serum IgM level at 72 h after infection while a single IL-18 injection did not. Interestingly, neutralization of IL-4 but not IFN-gamma partially suppressed the increased serum IgM. Liver mononuclear cells (MNCs) from the mice treated with multiple IL-18 injections significantly increased more production of not only IFN-gamma but also Th2 cytokines and IgM by in vitro lipopolysaccharide (LPS) stimulation than those from the phosphate-buffered saline (PBS)-treated mice, while liver MNCs from the single IL-18-injected mice also increased IFN-gamma production but significantly suppressed IL-4 and IgM production compared to those from the PBS-treated mice. Our findings suggest that multiple injections of IL-18 up-regulate both the cellular and humoral innate immunities, thereby enhancing host defence against bacterial infections.

Animals↗
PubMed2005

Analysis of the susceptibility of CD57 T cells to CD3-mediated apoptosis.

After stimulation with anti-CD3 antibody in vitro, CD57(+) T cells showed a greater susceptibility to apoptosis than CD57(-)alphabetaT cell receptor (TCR)(+) T cells (regular alphabeta T cells). The apoptotic fraction of CD57(+) T cells showed an increased production of active caspase-3. An increase in both Fas expression and Fas-ligand (FasL) production was also observed in CD57(+) T cells, whereas the expression of survivin was suppressed in CD57(+) T cells compared to that of regular alphabeta T cells. CD57(+) T cells display a biased expansion of a few Vbeta T cell fractions in individuals, but such Vbeta T cells were not specifically susceptible to CD3-mediated apoptosis. The TCR expression level of CD57(+) T cells was much lower than that of regular T cells and anti-TCR antibody stimulation induced a smaller apoptotic proportion of CD57(+) T cells than did anti-CD3 antibody. Although the CD3epsilon expression levels were similar in both T cell subsets, the CD3zeta level of CD57(+) T cells was significantly higher than that of regular T cells. These results suggest that several apoptotic and anti-apoptotic molecules are involved in the CD3-induced apoptosis of CD57(+) T cells and raise the possibility that the imbalance in expression of the CD3epsilon and CD3zeta chains may also contribute to the susceptibility of CD57(+) T cells to undergo apoptosis.

Adult↗
PubMed2005

A defective Th1 response of the spleen in the initial phase may explain why splenectomy helps prevent a Listeria infection.

Listeria monocytogenes (Listeria) are known to grow and proliferate in the liver while a splenectomy induces host resistance against a Listeria infection despite the fact that a splenectomy inhibits the Th1 response. Therefore, the mechanism by which a splenectomy helps to prevent the growth of Listeria still remains to be elucidated. After an i.v. challenge of Listeria (1 x 10(6) CFU) in C57BL/6 mice, Listeria rapidly increased in the spleen but not in the liver until 48 h. However, after this initial phase, Listeria remarkably grew in the liver. In contrast, when the mice received a splenectomy beforehand, no remarkable growth of Listeria in the liver was observed after Listeria challenge despite the fact that serum IFN-gamma and IL-12 levels at 24 h after Listeria challenge were significantly lower than those in the sham mice. However, the liver leucocytes from mice by 6 h after infection produced a substantial amount of IFN-gamma while spleen MNC did not, whereas spleen leucocytes at 24 h after Listeria challenge did. Consistently, the IFN-gamma and IL-12 levels in the tissue homogenates of the spleen were significantly lower than in those of the liver until 6 h after infection. This defective spleen Th1 response in the early phase of Listeria infection was corrected by an IL-18 i.p. injection just after the Listeria challenge. Our findings suggest that Listeria exploit the defective Th1 environment of the spleen in the initial phase and afterwards overcome the host defense mechanism of the liver.

Animals↗
PubMed2001

Long-term cultivation of colorectal carcinoma cells with anti-cancer drugs induces drug resistance and telomere elongation: an in vitro study.

BACKGROUND: The role of telomerase activation in the expression and/or maintenance of drug resistance is not clearly understood. Therefore, we investigated the relationships, among the telomerase activity, telomere length and the expression of multidrug resistance genes in colorectal cancer cell lines cultivated with anti-cancer drugs. METHODS: LoVo and DLD-1 cells were continuously grown in the presence of both CDDP and 5-FU for up to 100 days. Cell proliferation, telomerase activity, telomere length and the expression of multidrug resistance genes were serially monitored as the PDL increased. RESULTS: The expression of multidrug resistance genes tended to increase as the PDL increased. However, an abnormal aneuploid clone was not detected as far as the cells were monitored by a DNA histogram analysis. Tumor cells showing resistance to anti-cancer drugs revealed a higher cell proliferation rate. The telomere length gradually increased with a progressive PDL. The telomerase activity reached a maximum level at 15 PDL in LoVo cells and at 27 PDL in DLD-1 cells. An increase in the mRNA expression of the telomerase components, especially in hTERT and in hTR, was observed at the same PDLs. CONCLUSIONS: These results suggest that a high telomerase activity and an elongation of telomeres both appear to help maintain and/or increase drug resistance in colorectal cancer cells. Cancer cells with long telomeres and a high proliferative activity may thus be able to better survive exposure to anti-cancer drugs. This is presumably due to an increased chromosome stability and a strong expression of both mdr-1 and MRP genes.

Adenocarcinoma↗
PubMed2001

Maternal germinal mosaicism of X-linked agammaglobulinemia.

X-linked agammaglobulinemia (XLA) is an immunodeficiency caused by abnormalities in tyrosine kinase (BTK), and is characterized by a deficiency of peripheral blood B cells. We studied cytoplasmic expression of BTK protein and analyzed the BTK gene (BTK) in peripheral blood mononuclear cells from two siblings with XLA and additional family members. Cytoplasmic expression of BTK protein in monocytes was not detected in either patient with XLA. A single base deletion (C563) in BTK-exon 6, which encodes the TH domain, was identified in both XLA patients. However, normal cytoplasmic expression of BTK protein in monocytes was detected in their mother without any BTK mutation. These results strongly suggest germinal mosaicism in the mother.

Agammaglobulinaemia Tyrosine Kinase↗
PubMed2001

Telomerase activity and expression of human telomerase RNA component and human telomerase reverse transcriptase in lung carcinomas.

The aim of this study was to evaluate the usefulness of determination of telomerase activity and expression of human telomerase RNA component (hTERC) and human telomerase reverse transcriptase (hTERT) for the diagnosis of lung carcinomas. The tissues studied consisted of 115 carcinomas and adjacent nonneoplastic lung, which were removed surgically without previous chemotherapy or radiotherapy. Telomerase activity was determined using a semiquantitative polymerase chain reaction-based telomeric repeat amplification protocol (TRAP) assay. The results obtained were classified into high and low telomerase groups. Localization of expression was examined by using in situ hybridization and immunohistochemistry. The correlation between telomerase activity in lung carcinoma and clinicopathologic features, including prognosis, was investigated. Telomerase activity in lung carcinomas was detected in 107 of 115 (93%) lung carcinomas, but not in any adjacent noncancerous tissues, and was significantly higher in small cell carcinoma than in any other histologic type. This activity also was significantly higher in poorly differentiated than in well-differentiated squamous cell carcinomas and adenocarcinomas. The overall survival rate (P =.020) was significantly lower in the high telomerase group. Messenger RNAs for hTERC and hTERT were mainly detected in the cytoplasm of cancer cells by in situ hybridization, and TERT protein was localized in the nuclei of these cells by immunohistochemical staining. Determinations of telomerase activity by in situ hybridization, immunohistochemistry, and TRAP assay are useful for evaluating the diagnosis and prognosis of lung carcinomas.

Adenocarcinoma↗
PubMed2001

Telomerase activation and MAPK pathways in regenerating hepatocytes.

Although there have been many reports on the relationship between the activation of telomerase and carcinogenesis, the role of telomerase in normal cellular growth is still unclear. Recently, the telomerase upregulation during the process of liver regeneration has been reported, but the precise time course of its activity and factors contributing to the activation of telomerase have not yet been fully elucidated. In the present review, we demonstrate the relationship between the activation of the telomerase, the cell cycle progression and the growth-related signaling during the liver regeneration process using an in vivo mouse partial hepatectomy model. Moreover, the importance of the role of the MAPK pathways on the telomerase activity in regenerating hepatocytes is also displayed by using an in vitro culture model. In conclusion, the telomerase activity is upregulated before hepatocytes enter the S phase, and some growth factors such as EGF and HGF contribute to this process. The activation of the growth-related signaling pathways seems to play essential roles in the upregulation of the telomerase activity.

Animals↗
PubMed2000

Different mechanisms between premitotic apoptosis and postmitotic apoptosis in X-irradiated U937 cells.

PURPOSE: Apoptosis is currently being evaluated for its importance as a pathway of radiation-induced cell death. However, the difference in the mechanisms between premitotic and postmitotic apoptosis following X-irradiation remains not well understood. We show here that the human monoblastoid cell line U937 can be induced to undergo these two different types of apoptosis. METHODS AND MATERIALS: U937 cells were irradiated at a dose of 5 or 20 Gy, and the DNA fragmentation rate was measured by both flow cytometric analysis and gel electrophoresis. Activation of caspase-3 was detected by Western blot analysis and fluorogenic assay using acetyl-Asp-Glu-Val-Asp-7-amino-4-methyl-coumarin (Ac-DEVD-AMC). Detection of mitochondrial transmembrane potential (DeltaPsi) was performed by using Rho123. Chasing of S-phase fraction following X-irradiation was performed after labeling with 5-bromo-2'-deoxyuridine (BrdU). Thymidine was used for synchronization of the cells. Inhibition of caspase-3 activity was achieved by Acetyl-Asp-Glu-Val-Asp-aldehyde (Ac-DEVD-CHO). RESULTS: Time courses of the apoptotic rates, caspase activation, and DeltaPsi indicated that two different types of cell death were induced by the different X-ray doses. High-dose X-ray (20 Gy) induced a rapid and strong apoptosis, whereas low-dose X-ray (5 Gy) induced a slow and mild apoptosis. Cell-cycle analyses revealed that there was cell death before cell division in the former apoptosis but the cells must be dying after cell division in the latter apoptosis. By means of cell-cycle synchronization, the S-phase cells proved to be the most sensitive fraction to premitotic apoptosis, but an obvious difference in the susceptibility to cell death among the cell-cycle phases was not observed in postmitotic apoptosis. Ac-DEVD-CHO treatment effectively blocked caspase activity and premitotic apoptosis, but it failed to block postmitotic apoptosis. CONCLUSIONS: Irradiation of U937 cells at different X-ray doses induced two different types of apoptotic cell death, premitotic apoptosis and postmitotic apoptosis, which are characterized by the time course and cell-cycle specificity. Decision concerning these two types of apoptotic cell death may be made by the difference in the magnitude of cell damage following X-irradiation.

Apoptosis↗
PubMed2000

Identification of the promoter region of human placental 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase gene.

The placenta-type isozyme of human 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (HP2K) is expressed in several tissues such as placenta, brain, testis, liver, kidney, skeletal muscle, and primary blood mononuclear cells. To better understand the regulation of HP2K gene expression, we isolated and characterized its genomic DNA, which includes the promoter region. The results of oligo-capping analysis indicate that the transcription start point (tsp) is an adenine residue 329 bp upstream of the translational start codon. DNA sequence analysis of this gene shows that the promoter region that contains the TATA box sequence and the 5'-UTR is different from the other known PFK-2/F2, 6BPase genes. In addition, its 5'-flanking and 5'-UTR both have G + C-rich sequences containing Sp1 binding sites. To identify the promoter/enhancer region of HP2K gene, we performed transfection analyses of human choriocarcinoma BeWo cells with HP2K promoter-luciferase constructs. These experiments identified a promoter region 164 bp upstream from the tsp and an enhancer region between -1265 and -1329 on the 5'-flanking sequences. We also showed that Sp1 sites were not essential for HP2K transcription. Following transfection, stimulation experiments with serum, progesterone and phorbol 12-myristate 13-acetate showed that only the construct with the enhancer containing putative early growth response-1 binding motif was responsive to serum. We propose that the transcription of HP2K is strictly controlled by tissue-specific factors even though its genomic DNA contains several transcriptional elements.

5' Untranslated Regions↗
PubMed2000

PR-000350, a novel hypoxic radiosensitizer, enhances tumor cell killing by promoting apoptosis preferentially in the S-phase fraction.

PR-000350, a novel hypoxic radiosensitizer, is a 2-nitroimidazole nucleoside analog and has begun to be used for clinical cancer therapy. In this study, using U937 monoblastoid cells we investigated the mechanisms of enhanced cell killing by PR-000350. When cells were irradiated under an extremely hypoxic condition, the apoptotic rate was strongly suppressed. However, a remarkable increase in the DNA fragmentation rate as well as in the ladder formation was observed when hypoxic cells were irradiated in the presence of 5 mM PR-000350. DNA histograms of the PR-000350 treated group showed enhancement of the sub-G1 fraction and simultaneous suppression of the progression of the cell cycle from the S to G2/M phase at 4-8 h after X-irradiation, suggesting the importance of the S phase in the induction of apoptotic cell death. Flow cytometric and immunohistochemical analyses after BrdU labelling revealed that apoptotic cell death is induced mainly in the BrdU-positive cells. In addition, by using cell synchronization technique it was proved that the S phase is the most sensitive fraction to the radiosensitizing effect of PR-000350. These results suggest that PR-000350 strongly enhances tumor cell killing by promoting X-ray induced-apoptosis preferentially in the S-phase fraction. PR-000350 is a new type radiosensitizer and promise to provide an effective anti-cancer activity against hypoxic tumor cells that are resistant to the usual radiotherapy.

Anaerobiosis↗
PubMed2000

Clinical significance of telomerase activity in biopsy specimens of gastric cancer.

Telomerase has been reported to be activated in most immortal cells and human cancers. The purpose of this study was to assess the clinical significance of telomerase activity in biopsy specimens of gastric cancer. Telomerase activity in endoscopic biopsy specimens obtained preoperatively from 31 patients with gastric cancer was determined semiquantitatively using the telomeric repeat amplification protocol assay, a polymerase chain reaction-based assay. Cancer tissues had significantly higher telomerase activity than adjacent normal tissues (13.9 +/-2.0% vs. 7.0 +/- 0.8%; p < 0.05). The ratio of the telomerase activity in cancer tissues to that in normal tissues (telomerase index) was significantly higher in tumors invading the proper muscle layer or deeper or in tumors with moderate or marked lymphatic invasion than in tumors without these invasive factors (4.7 +/- 1.4 vs. 1.1 +/- 0.1 for depth of invasion and 4.4 +/- 1.3 vs. 1.2 +/- 0.2 for lymphatic invasion; p < 0.05 for both). These results suggest that the analysis of telomerase activity in biopsy specimens might contribute to preoperative assessment of the invasive activity or stage of gastric cancer.

Adult↗
PubMed2000

Urokinase type plasminogen activator and its receptor regulate the invasive potential of gastric cancer cell lines.

To assess the role of urokinase-type plasminogen activator (uPA) and uPA receptor (uPAR) on the invasive potential of cancer cells, in vitro experiments were performed using two human gastric cancer cell lines, NUGC-3 and MKN-28. NUGC-3 cells secreted a higher level of uPA than MKN-28 cells, while the uPAR expression of NUGC-3 cells was lower than that of MKN-28 cells. Both cancer cell lines expressed Met protein and did not express hepatocyte growth factor (HGF). In Matrigel invasion assay, MKN-28 cells demonstrated significantly lower invasion index than NUGC-3 cells. The addition of exogenous uPA significantly increased the invasive activity of MKN-28 cells. The uPA expression in NUGC-3 cells was enhanced by adding conditioned media of fibroblast cells or HGF. These results suggest that uPA promotes the invasive capacity of the uPAR-positive cancer cells, and that stromal cells may play an important role in cancer cell invasion by supplying uPA and/or promoting uPA production.

Adenocarcinoma↗
PubMed2000

Hyperbaric stress during saturation diving induces lymphocyte subset changes and heat shock protein expression.

To clarify the cellular responses and biochemical markers of hyperbaric stress, we investigated heat shock protein (hsp) expression and subset changes of human peripheral blood lymphocytes during saturation diving. Five healthy male subjects underwent a 39-day saturation dive to the maximal storage pressure of 4.1 MPa [400 meters of sea water (msw)]. During the saturation dive, lymphocyte subset changes were detected using a flow cytometer, and increased expressions of hsp 72/73 and hsp 27 were observed by Western blot analysis. Lymphocyte subset changes included a decrease in CD4:CD8 ratio and in the fraction of CD4+ T cells as well as an increase in NK cells, especially during the 400-msw bottom phase. An increased expression of hsp 27 compared to hsp 72/73 was obvious, especially during the hold period at 100 msw. These results suggest that changes in lymphocyte subsets and hsp expression are useful markers for stress responses during saturation diving. These changes may also be useful for testing the barotolerance of divers for saturation diving.

Biomarkers↗
PubMed1999

Role of G1 phase in the UV-induced apoptosis of EL-4 mouse lymphoma cells.

Although UV is known to induce apoptotic cell death to various animal cells, relationship between cell cycle and UV-induced apoptosis is still unclear. In this study, we investigated the role of G1 phase in UV-induced apoptosis by using EL-4 mouse lymphoma cells which have wild type p53. After 500 J/m2 UV irradiation, an increase of apoptotic fraction was accompanied by cell cycle accumulation in the G1 phase. Apoptotic fraction after UV-exposure was remarkably augmented by treatment with 2-AP, a G1 checkpoint inhibitor. In contrast, aphidicolin, an inhibitor of DNA polymerase-alpha, suppressed the rate of apoptotic fraction. These results suggest that mandatory cell cycle progression from G1 to S leaves the damaged DNA unrepaired and may increase the apoptotic fraction. To investigate the precise mechanism in the G1 phase, UV was exposed to the G1-synchronized cells and apoptotic fraction was serially observed. Synchronized EL-4 cells passed through the G1 phase in 8 h. Within the G1 phase, late-G1 cells (6 h after M) were more sensitive to UV-induced apoptosis than early-G1 cells (2 h after M) (49.7 +/- 9.0% vs. 41.5 +/- 8.5%, p < 0.05). In HL-60 cells, lacking in p53 expression, such a difference was not observed. Western blot analysis revealed that expression of p53 in synchronized EL-4 cells was increasingly enhanced during G1 phase. After UV-exposure, p53 expression gradually decreased in early-G1 cells, but it was kept at almost the same level in late-G1 cells. In addition, bcl-2 expression in early-G1 cells showed a more rapid and larger increase than that in late-G1 cells. These results suggest that susceptibility of the G1 cells to UV-induced apoptosis depends on their position within the G1 phase, and late-G1 is more sensitive than early-G1. Sensitivity to UV-induced apoptosis is closely related to the expression level of p53 and bcl-2 proteins. Early-G1 cells may be able to take enough time to repair damaged DNA until they reach the G1 checkpoint compared to the late-G1 cells.

Journal Article↗
PubMed1999

Different cell cycle mechanisms between UV-induced and X-ray-induced apoptosis in WiDr colorectal carcinoma cells.

Although DNA-damaging agents such as ultraviolet (UV) and X-ray can induce apoptosis, the difference in the apoptotic mechanism is not clearly understood. In the present study, we investigated the effects of these two genotoxic agents on the induction of DNA damage and subsequent apoptotic cell death from the viewpoint of cell cycle regulation by using WiDr cells. Transient G1 arrest was observed after UV exposure, whereas G2 but not G1 arrest was induced after X-ray irradiation. UV-exposure could induce G1 arrest in both mutant-type (mt-p53) and wild-type p53 (wt-p53) cells, but obvious G1 arrest was not observed in the cells lacking in p53 expression. An increase in the DNA fragmentation was observed at S phase in UV-irradiated cells and at G2 phase in X-irradiated cells, respectively. UV-irradiated cells showed an increase production of p53 protein and accumulation of p21 protein. On the contrary, both p53 and p21 proteins remained at a low level in X-irradiated cells. Treatment with aphidicolin, an S phase blocking agent, prolonged cell cycle arrest and reduced the rate of apoptotic cell death in both UV-irradiated and X-irradiated cells. From these results, it is suggested that UV-induced apoptosis occurs mainly at S phase and is regulated by increased production of p53 and p21 proteins, while X-ray-induced apoptosis occurs after G2 blockade and may be independent of p53.

Journal Article↗