Tumor cell-specific inhibition of inducible nitric oxide synthase activation by tiazofurin

The effects of tiazofurin (TR) on proliferation and cytokine-induced nitric oxide (NO) production in the L929 fibrosarcoma cell line and murine embryonic fibroblasts were investigated. Treatment with TR inhibited the growth of nonconfluent L929 cells in a dose-dependent manner. TR, at concentrations not affecting cell viability or proliferation, markedly decreased IFN-gamma + LPS-induced expression of inducible NO synthase (iNOS) mRNA and, subsequently. NO production in confluent L929 cultures. However, TR did not interfere with the IFN-gamma -triggered expression of mRNA for IRF-1, an important iNOS transcription factor, implying that TR interferes with some other intracellular pathway involved in iNOS induction triggered by IFN-gamma + LPS. In contrast to the results obtained in L929 cells, iNOS mRNA expression induced by IFN-gamma + LPS in murine embryonic fibroblasts was resistant to TR, indicating a tumor-selective action of this agent. (C) 2001 Elsevier Science B.V. All rights reserved.nul

The mechanisms of 6-hydroxydopamineInduced astrocyte death

Treatment with 6-hydroxydopamine significantly reduced the viability of cultured rat primary astrocytes, rat astrocytoma cell line C6, and human astrocytoma cell line U251. 6-Hydroxydopamine-treated astrocytes exhibited altered nuclear morphology, DNA fragmentation, and reduced intracellular esterase activity, which indicated apoptotic cell death. Astrocytes were protected by neutralization of 6-hydroxydopamine autooxidation products H2O2, O-2, and -OH, but not by cell-derived or chemically generated anti-apoptotic free radical nitric oxide. Finally, 6-hydroxydopamine activated extracellular signal-regulated kinase in astrocytes and selective inhibitor of extracellular signal-regulated kinase activation partially prevented astrocyte death. Taken together, these data indicate that 6-hydroxydopamine-triggered oxidative stress induces extracellular signal-regulated kinase-dependent apoptotic death of astrocytes.nul

The mechanisms of 6-hydroxydopamineInduced astrocyte death

Treatment with 6-hydroxydopamine significantly reduced the viability of cultured rat primary astrocytes, rat astrocytoma cell line C6, and human astrocytoma cell line U251. 6-Hydroxydopamine-treated astrocytes exhibited altered nuclear morphology, DNA fragmentation, and reduced intracellular esterase activity, which indicated apoptotic cell death. Astrocytes were protected by neutralization of 6-hydroxydopamine autooxidation products H2O2, O-2, and -OH, but not by cell-derived or chemically generated anti-apoptotic free radical nitric oxide. Finally, 6-hydroxydopamine activated extracellular signal-regulated kinase in astrocytes and selective inhibitor of extracellular signal-regulated kinase activation partially prevented astrocyte death. Taken together, these data indicate that 6-hydroxydopamine-triggered oxidative stress induces extracellular signal-regulated kinase-dependent apoptotic death of astrocytes.nul

Tumor cell-specific inhibition of inducible nitric oxide synthase activation by tiazofurin

The effects of tiazofurin (TR) on proliferation and cytokine-induced nitric oxide (NO) production in the L929 fibrosarcoma cell line and murine embryonic fibroblasts were investigated. Treatment with TR inhibited the growth of nonconfluent L929 cells in a dose-dependent manner. TR, at concentrations not affecting cell viability or proliferation, markedly decreased IFN-gamma + LPS-induced expression of inducible NO synthase (iNOS) mRNA and, subsequently. NO production in confluent L929 cultures. However, TR did not interfere with the IFN-gamma -triggered expression of mRNA for IRF-1, an important iNOS transcription factor, implying that TR interferes with some other intracellular pathway involved in iNOS induction triggered by IFN-gamma + LPS. In contrast to the results obtained in L929 cells, iNOS mRNA expression induced by IFN-gamma + LPS in murine embryonic fibroblasts was resistant to TR, indicating a tumor-selective action of this agent. (C) 2001 Elsevier Science B.V. All rights reserved.nul