The Experts below are selected from a list of 123 Experts worldwide ranked by ideXlab platform
Kazuo Umezawa - One of the best experts on this subject based on the ideXlab platform.
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induction of hydrogen peroxide production and bax expression by caspase 3 like proteases in tyrosine kinase inhibitor induced apoptosis in human small cell lung carcinoma cells
Experimental Cell Research, 1998Co-Authors: Siro Simizu, Kazuo Umezawa, Minoru Takada, Nadir Arber, Masaya ImotoAbstract:In our previous studies (S. Simizu, et al., 1996, Cancer Res. 56, 4978-4982), we reported that apoptosis of human small cell lung carcinoma (SCLC) cells induced by protein tyrosine kinase inhibitors, such as Erbstatin and herbimycin A, was mediated by H2O2 via a newly synthesized protein(s). In the present study, we demonstrated that induction of apoptosis by Erbstatin resulted in activation of caspase-3(-like) proteases, which are interleukin-1 beta-converting enzyme family proteases (caspases) and that inhibition of these protease activities reduced the extent of cell death and H2O2 generation. We also demonstrated that expression of apoptotic protein Bax was induced by Erbstatin. Erbstatin-induced Bax expression was inhibited by the inhibitor of caspase-3(-like) proteases. These results indicate that generation of intracellular H2O2 and Bax expression in tyrosine kinase inhibitor-induced apoptosis were modulated by the activation of caspase-3(-like) proteases in SCLC cells.
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involvement of hydrogen peroxide production in Erbstatin induced apoptosis in human small cell lung carcinoma cells
Cancer Research, 1996Co-Authors: Siro Simizu, Masaya Imoto, Noriyuki Masuda, Minoru Takada, Kazuo UmezawaAbstract:Tyrosine kinase inhibitor, Erbstatin, induced morphological apoptosis and DNA fragmentation in human small cell lung carcinoma (SCLC) cells. Erbstatin-induced apoptosis was inhibited by antioxidants, whereas Erbstatin-inhibited tyrosine phosphorylation was not affected by them. Erbstatin was shown by means of flow cytometry to induce hydrogen peroxide generation. Furthermore, hydrogen peroxide induced morphological apoptosis and DNA fragmentation in the SCLC cells. We also demonstrated that Erbstatin-induced hydrogen peroxide production and DNA fragmentation were partially suppressed by inhibition of protein synthesis. Thus, Erbstatin-induced apoptosis would be due to hydrogen peroxide generation via newly synthesized protein.
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induction of apoptosis by Erbstatin in mouse leukemia l1210 cells
Bioscience Biotechnology and Biochemistry, 1994Co-Authors: Siro Simizu, Masaya Imoto, Kazuo UmezawaAbstract:Erbstatin, a tyrosine kinase inhibitor, has antitumor activity on L1210 mouse leukemia. We tried to find the mechanism of this cytotoxic effect of Erbstatin. Erbstatin increased trypan blue exclusion in cultured LI210 cells. The cytotoxic action of Erbstatin was accompanied with shrinking of the cells and internucleosomal DNA fragmentation, characteristics of apoptosis. The DNA fragmentation was induced with other tyrosine kinase inhibitors as well, methyl 2,5-dihydroxycinnamate and herbimycin A. In addition, intracellular tyrosine phosphorylation was inhibited by Erbstatin before cell death. Erbstatin-induced DNA fragmentation was prevented by zinc ions, but not by cycloheximide or 12-O-tetradecanoylphorbol 13-acetate (TPA). Thus, Erbstatin induced apoptotic cell death in L1210 cells by inhibiting tyrosine kinase.
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inhibition of t cell receptor mediated signal transduction by Erbstatin
Bioscience Biotechnology and Biochemistry, 1994Co-Authors: Masaya Imoto, Takeshi Nakamura, Shinichiro Tanaka, Kazuo UmezawaAbstract:Erbstatin, a tyrosine kinase inhibitor, inhibited p59fyn- and p56lck-kinases in vitro with IC50s of 0.21 and 0.18 μg/ml, respectively. Inositol phosphates formation, enhanced by anti-CD3, was also inhibited by Erbstatin. Moreover, Erbstatin treatment prevented anti-CD3-induced interleukin 2 (IL-2) production, but phorbol ester-induced IL-2 production was not affected by Erbstatin.
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inhibition of serum induced m phase progression by a tyrosine kinase inhibitor Erbstatin
Biochemical and Biophysical Research Communications, 1993Co-Authors: D Sugata, Kaoru Yamashita, Kazuo UmezawaAbstract:Abstract A tyrosine kinase inhibitor, Erbstatin, increased the number of M-phase cells in exponentially growing NRK, NIH3T3, and RSV-NRK cells. In synchronized NRK cells prepared by serum starvation or hydroxyurea treatment, Erbstatin also increased the number of M-phase cells in the presence of serum when added before M-phase. Erbstatin did not inhibit serum-induced DNA synthesis at all. The accumulated M-phase cells later divided even in the presence of Erbstatin, indicating that the effect of Erbstatin is reversible. An inactive analogue, 5′-O-methylErbstatin, did not increase the number of mitotic figures. Flow cytometric analysis indicated that Erbstatin reversibly accumulated 4n DNA containing cells when added to G1/S-synchronized NRK cells. Increased cellular H1 kinase activity at M-phase is decreased after mitosis, and this decrease was inhibited by Erbstatin. Thus tyrosine kinase is suggested to be involved in the progression of the M-phase.
Rudi Busse - One of the best experts on this subject based on the ideXlab platform.
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ca2 independent activation of the endothelial nitric oxide synthase in response to tyrosine phosphatase inhibitors and fluid shear stress
Circulation Research, 1998Co-Authors: Ingrid Fleming, Beate Fisslthaler, Johann Bauersachs, Rudi BusseAbstract:Abstract—Fluid shear stress enhances NO formation via a Ca2+-independent tyrosine kinase inhibitor–sensitive pathway. In the present study, we investigated the effects of the protein tyrosine phosphatase inhibitor phenylarsine oxide and of fluid shear stress on endothelial NO production as well as on the membrane association and phosphorylation of the NO synthase (NOS) III. Phenylarsine oxide (10 μmol/L) induced an immediate and maintained NO-mediated relaxation of isolated rabbit carotid arteries, which was insensitive to the removal of extracellular Ca2+ and the calmodulin antagonist calmidazolium. This phenylarsine oxide–induced vasodilatation was unaffected by genistein but abrogated by the tyrosine kinase inhibitor Erbstatin A. Incubation of native or cultured endothelial cells with phenylarsine oxide resulted in a time-dependent tyrosine phosphorylation of mainly Triton X-100–insoluble (cytoskeletal) proteins, along with a parallel change in the detergent solubility of NOS III, such that the enzyme ...
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intracellular ph and tyrosine phosphorylation but not calcium determine shear stress induced nitric oxide production in native endothelial cells
Circulation Research, 1996Co-Authors: Kazuhide Ayajiki, Ingrid Fleming, Markus Kindermann, Markus Hecker, Rudi BusseAbstract:Abstract Signaling pathways determining the shear stress–induced production of NO from endothelial cells in situ were investigated using a bioassay system in which shear stress was increased by inducing vasoconstriction in an endothelium-intact donor segment (rabbit iliac artery) while maintaining a constant luminal perfusion rate. Shear stress–induced NO production, as assessed by changes in the tone of a preconstricted endothelium-denuded detector ring, was biphasic and consisted of an initial transient (20- to 25-minute) Ca2+-dependent phase followed by a Ca2+-independent plateau phase, which was maintained as long as the donor segment remained constricted. Stretching the donor segments to their in vivo length abolished the initial phase without affecting the plateau phase of NO release. Inhibition of the Na+-H+ exchanger using HOE 694 elicited an intracellular acidification, which attenuated shear stress–induced NO production. The specific protein kinase C inhibitor, Ro 31-8220, was without effect, whereas the unspecific inhibitors, staurosporine and calphostin C, abolished the shear stress–induced production of NO. Erbstatin A, a tyrosine kinase inhibitor, attenuated the shear stress–induced tyrosine phosphorylation of specific cellular proteins and abrogated the associated NO production. In summary, these data indicate that shear stress activates the NO synthase at basal levels of [Ca2+]i via a mechanotransduction cascade that involves tyrosine phosphorylation and can be modulated by changes in pHi. The apparent fundamental alteration of the endothelial NO synthase under shear stress that renders its maintained activation independent of an increase in [Ca2+]i is probably the consequence of a change in the enzyme microenvironment.
Masaya Imoto - One of the best experts on this subject based on the ideXlab platform.
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induction of hydrogen peroxide production and bax expression by caspase 3 like proteases in tyrosine kinase inhibitor induced apoptosis in human small cell lung carcinoma cells
Experimental Cell Research, 1998Co-Authors: Siro Simizu, Kazuo Umezawa, Minoru Takada, Nadir Arber, Masaya ImotoAbstract:In our previous studies (S. Simizu, et al., 1996, Cancer Res. 56, 4978-4982), we reported that apoptosis of human small cell lung carcinoma (SCLC) cells induced by protein tyrosine kinase inhibitors, such as Erbstatin and herbimycin A, was mediated by H2O2 via a newly synthesized protein(s). In the present study, we demonstrated that induction of apoptosis by Erbstatin resulted in activation of caspase-3(-like) proteases, which are interleukin-1 beta-converting enzyme family proteases (caspases) and that inhibition of these protease activities reduced the extent of cell death and H2O2 generation. We also demonstrated that expression of apoptotic protein Bax was induced by Erbstatin. Erbstatin-induced Bax expression was inhibited by the inhibitor of caspase-3(-like) proteases. These results indicate that generation of intracellular H2O2 and Bax expression in tyrosine kinase inhibitor-induced apoptosis were modulated by the activation of caspase-3(-like) proteases in SCLC cells.
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involvement of hydrogen peroxide production in Erbstatin induced apoptosis in human small cell lung carcinoma cells
Cancer Research, 1996Co-Authors: Siro Simizu, Masaya Imoto, Noriyuki Masuda, Minoru Takada, Kazuo UmezawaAbstract:Tyrosine kinase inhibitor, Erbstatin, induced morphological apoptosis and DNA fragmentation in human small cell lung carcinoma (SCLC) cells. Erbstatin-induced apoptosis was inhibited by antioxidants, whereas Erbstatin-inhibited tyrosine phosphorylation was not affected by them. Erbstatin was shown by means of flow cytometry to induce hydrogen peroxide generation. Furthermore, hydrogen peroxide induced morphological apoptosis and DNA fragmentation in the SCLC cells. We also demonstrated that Erbstatin-induced hydrogen peroxide production and DNA fragmentation were partially suppressed by inhibition of protein synthesis. Thus, Erbstatin-induced apoptosis would be due to hydrogen peroxide generation via newly synthesized protein.
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induction of apoptosis by Erbstatin in mouse leukemia l1210 cells
Bioscience Biotechnology and Biochemistry, 1994Co-Authors: Siro Simizu, Masaya Imoto, Kazuo UmezawaAbstract:Erbstatin, a tyrosine kinase inhibitor, has antitumor activity on L1210 mouse leukemia. We tried to find the mechanism of this cytotoxic effect of Erbstatin. Erbstatin increased trypan blue exclusion in cultured LI210 cells. The cytotoxic action of Erbstatin was accompanied with shrinking of the cells and internucleosomal DNA fragmentation, characteristics of apoptosis. The DNA fragmentation was induced with other tyrosine kinase inhibitors as well, methyl 2,5-dihydroxycinnamate and herbimycin A. In addition, intracellular tyrosine phosphorylation was inhibited by Erbstatin before cell death. Erbstatin-induced DNA fragmentation was prevented by zinc ions, but not by cycloheximide or 12-O-tetradecanoylphorbol 13-acetate (TPA). Thus, Erbstatin induced apoptotic cell death in L1210 cells by inhibiting tyrosine kinase.
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inhibition of t cell receptor mediated signal transduction by Erbstatin
Bioscience Biotechnology and Biochemistry, 1994Co-Authors: Masaya Imoto, Takeshi Nakamura, Shinichiro Tanaka, Kazuo UmezawaAbstract:Erbstatin, a tyrosine kinase inhibitor, inhibited p59fyn- and p56lck-kinases in vitro with IC50s of 0.21 and 0.18 μg/ml, respectively. Inositol phosphates formation, enhanced by anti-CD3, was also inhibited by Erbstatin. Moreover, Erbstatin treatment prevented anti-CD3-induced interleukin 2 (IL-2) production, but phorbol ester-induced IL-2 production was not affected by Erbstatin.
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use of Erbstatin as protein tyrosine kinase inhibitor
Methods in Enzymology, 1991Co-Authors: Kazuo Umezawa, Masaya ImotoAbstract:Publisher Summary This chapter discusses the use of Erbstatin as protein-tyrosine kinase inhibitor. Streptomyces and other microorganisms produce antibiotics, anticancer agents, and enzyme inhibitors as secondary metabolites. Isolation of specific bioactive products in culture broths depends on the assay system. Erbstatin is easily inactivated in calf serum, and more stable analogs of Erbstatin have been looked for. Various Erbstatin analogs have been synthesized and tested for their inhibitory activity against tyrosine kinase. This analog inhibits tyrosine kinase in vitro, but are not active in vivo, because, being a polar molecule, it would penetrate the cells poorly.
Ingrid Fleming - One of the best experts on this subject based on the ideXlab platform.
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ca2 independent activation of the endothelial nitric oxide synthase in response to tyrosine phosphatase inhibitors and fluid shear stress
Circulation Research, 1998Co-Authors: Ingrid Fleming, Beate Fisslthaler, Johann Bauersachs, Rudi BusseAbstract:Abstract—Fluid shear stress enhances NO formation via a Ca2+-independent tyrosine kinase inhibitor–sensitive pathway. In the present study, we investigated the effects of the protein tyrosine phosphatase inhibitor phenylarsine oxide and of fluid shear stress on endothelial NO production as well as on the membrane association and phosphorylation of the NO synthase (NOS) III. Phenylarsine oxide (10 μmol/L) induced an immediate and maintained NO-mediated relaxation of isolated rabbit carotid arteries, which was insensitive to the removal of extracellular Ca2+ and the calmodulin antagonist calmidazolium. This phenylarsine oxide–induced vasodilatation was unaffected by genistein but abrogated by the tyrosine kinase inhibitor Erbstatin A. Incubation of native or cultured endothelial cells with phenylarsine oxide resulted in a time-dependent tyrosine phosphorylation of mainly Triton X-100–insoluble (cytoskeletal) proteins, along with a parallel change in the detergent solubility of NOS III, such that the enzyme ...
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intracellular ph and tyrosine phosphorylation but not calcium determine shear stress induced nitric oxide production in native endothelial cells
Circulation Research, 1996Co-Authors: Kazuhide Ayajiki, Ingrid Fleming, Markus Kindermann, Markus Hecker, Rudi BusseAbstract:Abstract Signaling pathways determining the shear stress–induced production of NO from endothelial cells in situ were investigated using a bioassay system in which shear stress was increased by inducing vasoconstriction in an endothelium-intact donor segment (rabbit iliac artery) while maintaining a constant luminal perfusion rate. Shear stress–induced NO production, as assessed by changes in the tone of a preconstricted endothelium-denuded detector ring, was biphasic and consisted of an initial transient (20- to 25-minute) Ca2+-dependent phase followed by a Ca2+-independent plateau phase, which was maintained as long as the donor segment remained constricted. Stretching the donor segments to their in vivo length abolished the initial phase without affecting the plateau phase of NO release. Inhibition of the Na+-H+ exchanger using HOE 694 elicited an intracellular acidification, which attenuated shear stress–induced NO production. The specific protein kinase C inhibitor, Ro 31-8220, was without effect, whereas the unspecific inhibitors, staurosporine and calphostin C, abolished the shear stress–induced production of NO. Erbstatin A, a tyrosine kinase inhibitor, attenuated the shear stress–induced tyrosine phosphorylation of specific cellular proteins and abrogated the associated NO production. In summary, these data indicate that shear stress activates the NO synthase at basal levels of [Ca2+]i via a mechanotransduction cascade that involves tyrosine phosphorylation and can be modulated by changes in pHi. The apparent fundamental alteration of the endothelial NO synthase under shear stress that renders its maintained activation independent of an increase in [Ca2+]i is probably the consequence of a change in the enzyme microenvironment.
Claude R Benedict - One of the best experts on this subject based on the ideXlab platform.
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synergistic effect of urotensin ii with mildly oxidized ldl on dna synthesis in vascular smooth muscle cells
Circulation, 2001Co-Authors: Takuya Watanabe, Rajbabu Pakala, Takashi Katagiri, Claude R BenedictAbstract:Background —The urotensin II (UII) found in coronary atheroma is the most potent vasoconstrictor known to date. Mildly oxidized LDL (moxLDL) contributes to atherogenesis and plaque formation. We assessed the effect of UII and its interaction with moxLDL and the oxidative components of moxLDL on vascular smooth muscle cell (VSMC) proliferation. Methods and Results —Growth-arrested VSMCs were incubated in serum-free medium with different concentrations of LDL, moxLDL, oxLDL, hydrogen peroxide, lysophosphatidylcholine, or 4-hydroxy-2-nonenal, with or without UII. [3H]Thymidine incorporation into DNA was measured as an index of VSMC proliferation. UII stimulated [3H]thymidine incorporation in a dose-dependent manner, with a maximal effect at a concentration of 50 nmol/L (161%). Low concentrations of UII potentiated the mitogenic effect of LDL (108% to 242%), oxLDL (129% to 302%), moxLDL (120% to 337%), hydrogen peroxide (177% to 226%), lysophosphatidylcholine (115% to 332%), and 4-hydroxy-2-nonenal (142% to 299%). The synergistic interaction between UII and moxLDL was partially inhibited by anti-Gq/11α antibody, the epidermal growth factor receptor tyrosine kinase inhibitor Erbstatin A (10 μmol/L), and the intracellular free radical scavenger N-acetylcysteine (400 μmol/L) and was completely inhibited by the c-Src tyrosine kinase inhibitor radicicol (10 μmol/L), the protein kinase C (PKC) inhibitor Ro31-8220 (0.1 μmol/L), and the mitogen-activated protein kinase (MAPK) kinase inhibitor PD098059 (10 μmol/L). Conclusions —Our results suggest that UII acts synergistically with moxLDL in inducing VSMC proliferation via the c-Src/PKC/MAPK pathway, which may explain the relatively rapid progression of atherosclerosis in patients with hypertension and hypercholesterolemia.