The in vivo modulating activity of recombinant transforming growth factor (TGF)-beta2 on acute to... more The in vivo modulating activity of recombinant transforming growth factor (TGF)-beta2 on acute toxoplasmosis was evaluated in both Toxoplasma gondii susceptible C57BL/6 and resistant BALB/c mice. TGF-beta2 lethally exacerbated Toxoplasma encephalitis in C57BL/6, but not in BALB/c mice. In C57BL/6 mice, TGF-beta2 induced a profound dose-dependent increase of the intracerebral parasitic load as well as a reduction of IFN-gamma levels in serum and cerebrospinal fluid with a coincident decrease of MHC class II antigen expression of macrophages, microglial cells, and B cells. Furthermore, TGF-beta2-treated C57BL/6 mice showed a reduced activation of CD4+ and CD8+ T cells and a diminished recruitment of immune cells to the brain. The TGF-beta2-mediated development of lethal toxoplasmosis in C57BL/6 mice was abolished by treatment with recombinant interferon (IFN)-gamma.
ABSTRACT Glioblastoma is an incurable primary brain tumors with one of the worst 5-year survival ... more ABSTRACT Glioblastoma is an incurable primary brain tumors with one of the worst 5-year survival rates among all cancers. Despite multimodal treatment involving neurosurgery, irradiation and temozolomide chemotherapy, the median overall survival is in the range of 15-16 months even in selected clinical trial populations. Thymosin beta 4 (TB4) is a pleiotropic actin-sequestering polypeptide that is involved in wound healing and developmental processes. TB4 gene silencing promotes differentiation of neural progenitor cells whereas TB4 overexpression initiates cortical folding of developing brain hemispheres. Moreover, TB4 is involved in migration, invasion and epithelial to mesenchymal transition in other cancer entities, e.g. colon cancer.
Herpes simplex virus-thymidine kinase/ganciclovir (HSV-TK/GCV) gene therapy was performed in five... more Herpes simplex virus-thymidine kinase/ganciclovir (HSV-TK/GCV) gene therapy was performed in five cases of recurrent glioblastoma multiforme. The mean age of cases, three males and two females, was 60 +/- 5 years old. All of the tumors were confirmed pathologically as glioblastoma multiforme and recurred after the initial treatments (surgery and irradiation). A total number of 1 x 10(9) vector producer cells (VPCs), which produce retroviral vectors containing the HSV-TK gene, was inoculated into the tumor-bed spaces after removal of the recurrent tumors. From the following 14th day to the 27th day, GCV was transfused 5 mg/kg i.v. twice a day. The effect of the HSV-TK/GCV gene therapy was evaluated by the Karnofsky performance scale and MRI findings sequentially, before the therapy and in the 1st, 2nd, 4th and 6th month after the VPCs inoculation. During the follow-up period of 12 months, two cases died (survival period; 8.4 and 9.9 months), whereas the other three are still alive for over 12 months (1-year survival; 60%). Karnofsky performance scale showed the maximum at the 2nd and 4th month in all cases; the mean performance rating of living cases was 80% and that of dead cases was 70%. MRI revealed progression in none of the cases until the 2nd month. These results obtained in five cases suggest that the HSV-TK/GCV gene therapy may promise a feasible approach against glioblastoma multiforme.
Herpes simplex virus-thymidine kinase/ganciclovir (HSV-TK/GCV) therapy was performed in five case... more Herpes simplex virus-thymidine kinase/ganciclovir (HSV-TK/GCV) therapy was performed in five cases of recurrent glioblastoma multiforme. In the last study, the authors demonstrated response of the HSV-TK/GCV therapy against tumor progression (Adachi N, et al.: No Shinkei Geka). The aim of this study is to estimate the biosafety of in vivo HSV-TK gene transfer and GCV administration in five cases. Six parameters were analyzed sequentially up to the 6th month after the vector producer cells (VPCs) inoculation as follows; i) clinical symptom, ii) vital sign, iii) peripheral blood cell count, iv) blood biochemical analysis, v) serological test, vi) molecular biological test in peripheral leukocytes. In addition, ten systemic organs extracted from the two subjects in whom death occurred were also analyzed biologically. One case suffered from transient deterioration of left hemiparesis on the 34th day, which could be considered a probably-related but not adverse event. Serological tests detected anti-VPC antibody at the 1st month in one case and anti-vector antibody at the 1st and 4th month in another. The other examinations revealed no abnormal findings at all. These data indicate that the HSV-TK/GCV therapy might be a satisfactorily safe approach against glioblastoma multiforme.
Synthesis of B cell-stimulating factor-2 (BSF-2) and IFN-gamma was shown in cerebrospinal fluids ... more Synthesis of B cell-stimulating factor-2 (BSF-2) and IFN-gamma was shown in cerebrospinal fluids (CSF) collected from mice with experimental viral meningitis. In the CSF, the level of BSF-2 started to increase 24 h after intracerebral infection with lymphocytic choriomeningitis virus (LCMV) with rapid increase after day 4. IFN-gamma was not detected in the CSF before day 5 or 6 after infection, but increased sharply thereafter. In athymic nude mice, LCMV infection did not result in meningitis, and both BSF-2 and IFN-gamma levels were only slightly and transiently elevated. These findings suggest that activated mature T cells are required for development of disease and production of both BSF-2 and IFN-gamma. As observed in mice, BSF-2 was also detected in 16 out of 19 CSF samples collected from patients with acute viral infections of the central nervous system (CNS). Intrathecal production of BSF-2 and IFN-gamma may be instrumental in local production of antiviral antibodies by B lym...
Prenatal exposure to diazepam and other benzodiazepines (BDZ) has been found to result in a marke... more Prenatal exposure to diazepam and other benzodiazepines (BDZ) has been found to result in a marked reduction of T-lymphocyte proliferation during postnatal development of rats. In search for pathogenic changes underlying this effect, we investigated the mitogen lipopolysaccharide (LPS) and concanavalin A (ConA) stimulated release of tumour necrosis factor (TNF)-alpha by mixed splenocytes of male offspring from Long Evans rats treated with 1.25 mg/kg per day diazepam from gestational day 14 to 20. In response to LPS, TNF-alpha release was found to be significantly lower in mixed splenocytes of two- and four-week-old treated than in control offspring. However, at eight weeks of age, prenatally diazepam-treated animals showed a significantly higher LPS-induced TNF-alpha release than control rats. Since monocytes/macrophages represent a major source of TNF-alpha, additional experiments were performed on purified spleen macrophages and lymphocytes stimulated with LPS. TNF-alpha release w...
Murine experimental meningitis models induced by either Escherichia coli LPS, live Streptococcus ... more Murine experimental meningitis models induced by either Escherichia coli LPS, live Streptococcus pneumoniae ,o rListeria mono- cytogenes were used to study the origin and potential function of soluble CD14 (sCD14) in the brain during bacterial meningitis. Whereas intracerebral infection caused only a minor and/or transient increase of sCD14 levels in the serum, dramatically elevated concentrations of sCD14 were detected in
The vascular and the nervous system are responsible for oxygen, nutrient, and information transfe... more The vascular and the nervous system are responsible for oxygen, nutrient, and information transfer and thereby constitute highly important communication systems in higher organisms. These functional similarities are reflected at the anatomical, cellular, and molecular levels, where common developmental principles and mutual crosstalks have evolved to coordinate their action. This resemblance of the two systems at different levels of complexity has been termed the "neurovascular link." Most of the evidence demonstrating neurovascular interactions derives from studies outside the CNS and from the CNS tissue of the retina. However, little is known about the specific properties of the neurovascular link in the brain. Here, we focus on regulatory effects of molecules involved in the neurovascular link on angiogenesis in the periphery and in the brain and distinguish between general and CNS-specific cues for angiogenesis. Moreover, we discuss the emerging molecular interactions of these angiogenic cues with the VEGF-VEGFR-Delta-like ligand 4 (Dll4)-Jagged-Notch pathway.
Intra-hippocampal injection of kainic acid (KA) in adult mice causes a focal lesion in the CA1 ar... more Intra-hippocampal injection of kainic acid (KA) in adult mice causes a focal lesion in the CA1 area and hilus of the dentate gyrus, as well as pronounced granule cell hypertrophy and dispersion. The lesion results in chronic focal seizures, with a two-week delay following KA-induced status epilepticus. Furthermore, seizures are preceded by infiltration of T lymphocytes into the lesioned tissue and of macrophage-like cells, strongly immunopositive for the monocyte marker F4/80, into the dentate gyrus, where they regulate granule cell dispersion and survival. Unexpectedly, depletion of CD4(+) and/or CD8(+) T lymphocytes by targeted gene deletion results in a marked shortening of the delay prior to seizure onset, suggesting a role of adaptive immunity in epileptogenesis (Zattoni et al. 2011, J. Neurosci. 31, 4037). Here, we investigated the specific role of adaptive immunity in this TLE model by adoptive i.v. transfer of immunopurified T cells in mutant mice lacking either CD4(+) T cel...
Glioblastoma are among the most angiogenic tumors. The molecular mechanisms that control blood ve... more Glioblastoma are among the most angiogenic tumors. The molecular mechanisms that control blood vessel formation by endothelial cells (EC) in glioblastoma remain incompletely understood. Transforming growth factor-β (TGF-β) is a key regulatory cytokine that has proinvasive and stemness-maintaining autocrine properties in glioblastoma and confers immunosuppression to the tumor microenvironment. Here we characterize potential pro- and anti-angiogenic activities of TGF-β in the context of glioblastoma in vitro, using human brain-derived microvascular endothelial cells (hCMEC/D3) and glioblastoma-derived endothelial cells (GMEC) as model systems. We find that TGF-β induces vascular endothelial growth factor (VEGF) and placental growth factor (PlGF) mRNA expression and protein release in a TGF-β receptor (TβR) II / activin-like kinase (ALK)-5-dependent manner under normoxia and hypoxia, defining potential indirect proangiogenic activity of TGF-β in glioblastoma. In parallel, exogenous TGF...
Transforming growth factor (TGF)-β is a central molecule maintaining the malignant phenotype of g... more Transforming growth factor (TGF)-β is a central molecule maintaining the malignant phenotype of glioblastoma. Anti-TGF-β strategies are currently being explored in early clinical trials. Yet, there is little contemporary data on the differential expression of TGF-β isoforms at the mRNA and protein level or TGF-β/Smad pathway activity in glioblastomas in vivo.Here we studied 64 newly diagnosed and 16 recurrent glioblastomas for the expression of TGF-β1-3, platelet-derived growth factor (PDGF)-B, and plasminogen activator inhibitor (PAI)-1 mRNA by RT-PCR and for the levels of TGF-β1-3 protein, phosphorylated Smad2 (pSmad2), pSmad1/5/8 and PAI-1 by immunohistochemistry.Among the TGF-β isoforms, TGF-β1 mRNA was the most, whereas TGF-β3 mRNA was the least abundant. TGF-β1-3 mRNA expression was strongly correlated, as was the expression of TGF-β1-3 mRNA, and of the TGF-β1-3 target genes, PDGF-B and PAI-1. TGF-β2 and TGF-β3 protein levels correlated well, whereas the comparison of the othe...
Targeting the oxygen stress response pathway is considered a promising strategy to exert antineop... more Targeting the oxygen stress response pathway is considered a promising strategy to exert antineoplastic activity in a broad spectrum of tumor types. Supporting this view, we summarize the mechanism of action of Taurolidine and Piperlongumine, two antineoplastic agents with strikingly broad tumor selectivity. Taurolidine enhances the oxidative stress (ROS) selectively in tumor cells. Its cytotoxicity for various tumor cells in vitro and in vivo, which includes tumor stem cells, is based on the induction of programmed cell death, largely via apoptosis but also necroptosis and autophagy. The redox-directed mechanism of action of Taurolidine is apparent from the finding that reducing agents e.g., N-acetylcysteine or glutathione impair its cytotoxicity, while its effectiveness is enhanced by agents which inhibit the cellular anti‑oxidant capacity. A similar redox-directed antineoplastic action is shown by Piperlongumine, a recently described experimental drug of plant origin. Taurolidine...
Human malignant gliomas arise from neural progenitor cells and/or dedifferentiated astrocytes. By... more Human malignant gliomas arise from neural progenitor cells and/or dedifferentiated astrocytes. By now, they are genetically so well characterized that several murine glioma models have emerged that faithfully reiterate the typical histological features of the disease. In experimental animals, only one or two elements of the growth factor/Ras, PI3K/PTEN/PKB, p53/ARF/HDM2, and p16/Rb/cyclinD/CDK4 pathways are targeted. In human gliomas, many additional genes and pathways are targeted due to a most severe mutator phenotype that leads to the accumulation of countless epigenetic and genetic alterations. Changes that convey a growth advantage are selected for, leading to overgrowth of precursor cell populations with increasingly malignant tumor cell clones. While murine models represent a powerful tool for elucidating the role of genetic pathways, mechanisms of response and resistance to new therapeutic agents might be fundamentally different due to the high degree of genomic instability ...
Regulation of epithelial and endothelial permeability is essential for proper function of compart... more Regulation of epithelial and endothelial permeability is essential for proper function of compartmentalized organisms, and tyrosine phosphorylation plays an important role in this process. We analyzed the impact of protein tyrosine phosphatase (PTP) inhibition on the structure of endothelial junctional proteins. In human umbilical vein endothelial cells (HUVECs) the PTP inhibitors phenylarsine oxide (PAO) and pervanadate induced proteolysis of the tight junction protein occludin. Occludin proteolysis was inhibited by the metalloproteinase inhibitor 1,10-phenanthroline (PHEN), but not by inhibitors against other types of proteases. The junctional proteins ZO-1, cadherin and beta-catenin were not cleaved. Under conditions of occludin proteolysis, PAO treatment elevated permeability for FITC-dextran. Simultaneous incubation of HUVECs with PAO and PHEN inhibited the rise in permeability by more than 60%. PAO treatment lead to progressive disappearance of occludin from the cell periphery...
The in vivo modulating activity of recombinant transforming growth factor (TGF)-beta2 on acute to... more The in vivo modulating activity of recombinant transforming growth factor (TGF)-beta2 on acute toxoplasmosis was evaluated in both Toxoplasma gondii susceptible C57BL/6 and resistant BALB/c mice. TGF-beta2 lethally exacerbated Toxoplasma encephalitis in C57BL/6, but not in BALB/c mice. In C57BL/6 mice, TGF-beta2 induced a profound dose-dependent increase of the intracerebral parasitic load as well as a reduction of IFN-gamma levels in serum and cerebrospinal fluid with a coincident decrease of MHC class II antigen expression of macrophages, microglial cells, and B cells. Furthermore, TGF-beta2-treated C57BL/6 mice showed a reduced activation of CD4+ and CD8+ T cells and a diminished recruitment of immune cells to the brain. The TGF-beta2-mediated development of lethal toxoplasmosis in C57BL/6 mice was abolished by treatment with recombinant interferon (IFN)-gamma.
ABSTRACT Glioblastoma is an incurable primary brain tumors with one of the worst 5-year survival ... more ABSTRACT Glioblastoma is an incurable primary brain tumors with one of the worst 5-year survival rates among all cancers. Despite multimodal treatment involving neurosurgery, irradiation and temozolomide chemotherapy, the median overall survival is in the range of 15-16 months even in selected clinical trial populations. Thymosin beta 4 (TB4) is a pleiotropic actin-sequestering polypeptide that is involved in wound healing and developmental processes. TB4 gene silencing promotes differentiation of neural progenitor cells whereas TB4 overexpression initiates cortical folding of developing brain hemispheres. Moreover, TB4 is involved in migration, invasion and epithelial to mesenchymal transition in other cancer entities, e.g. colon cancer.
Herpes simplex virus-thymidine kinase/ganciclovir (HSV-TK/GCV) gene therapy was performed in five... more Herpes simplex virus-thymidine kinase/ganciclovir (HSV-TK/GCV) gene therapy was performed in five cases of recurrent glioblastoma multiforme. The mean age of cases, three males and two females, was 60 +/- 5 years old. All of the tumors were confirmed pathologically as glioblastoma multiforme and recurred after the initial treatments (surgery and irradiation). A total number of 1 x 10(9) vector producer cells (VPCs), which produce retroviral vectors containing the HSV-TK gene, was inoculated into the tumor-bed spaces after removal of the recurrent tumors. From the following 14th day to the 27th day, GCV was transfused 5 mg/kg i.v. twice a day. The effect of the HSV-TK/GCV gene therapy was evaluated by the Karnofsky performance scale and MRI findings sequentially, before the therapy and in the 1st, 2nd, 4th and 6th month after the VPCs inoculation. During the follow-up period of 12 months, two cases died (survival period; 8.4 and 9.9 months), whereas the other three are still alive for over 12 months (1-year survival; 60%). Karnofsky performance scale showed the maximum at the 2nd and 4th month in all cases; the mean performance rating of living cases was 80% and that of dead cases was 70%. MRI revealed progression in none of the cases until the 2nd month. These results obtained in five cases suggest that the HSV-TK/GCV gene therapy may promise a feasible approach against glioblastoma multiforme.
Herpes simplex virus-thymidine kinase/ganciclovir (HSV-TK/GCV) therapy was performed in five case... more Herpes simplex virus-thymidine kinase/ganciclovir (HSV-TK/GCV) therapy was performed in five cases of recurrent glioblastoma multiforme. In the last study, the authors demonstrated response of the HSV-TK/GCV therapy against tumor progression (Adachi N, et al.: No Shinkei Geka). The aim of this study is to estimate the biosafety of in vivo HSV-TK gene transfer and GCV administration in five cases. Six parameters were analyzed sequentially up to the 6th month after the vector producer cells (VPCs) inoculation as follows; i) clinical symptom, ii) vital sign, iii) peripheral blood cell count, iv) blood biochemical analysis, v) serological test, vi) molecular biological test in peripheral leukocytes. In addition, ten systemic organs extracted from the two subjects in whom death occurred were also analyzed biologically. One case suffered from transient deterioration of left hemiparesis on the 34th day, which could be considered a probably-related but not adverse event. Serological tests detected anti-VPC antibody at the 1st month in one case and anti-vector antibody at the 1st and 4th month in another. The other examinations revealed no abnormal findings at all. These data indicate that the HSV-TK/GCV therapy might be a satisfactorily safe approach against glioblastoma multiforme.
Synthesis of B cell-stimulating factor-2 (BSF-2) and IFN-gamma was shown in cerebrospinal fluids ... more Synthesis of B cell-stimulating factor-2 (BSF-2) and IFN-gamma was shown in cerebrospinal fluids (CSF) collected from mice with experimental viral meningitis. In the CSF, the level of BSF-2 started to increase 24 h after intracerebral infection with lymphocytic choriomeningitis virus (LCMV) with rapid increase after day 4. IFN-gamma was not detected in the CSF before day 5 or 6 after infection, but increased sharply thereafter. In athymic nude mice, LCMV infection did not result in meningitis, and both BSF-2 and IFN-gamma levels were only slightly and transiently elevated. These findings suggest that activated mature T cells are required for development of disease and production of both BSF-2 and IFN-gamma. As observed in mice, BSF-2 was also detected in 16 out of 19 CSF samples collected from patients with acute viral infections of the central nervous system (CNS). Intrathecal production of BSF-2 and IFN-gamma may be instrumental in local production of antiviral antibodies by B lym...
Prenatal exposure to diazepam and other benzodiazepines (BDZ) has been found to result in a marke... more Prenatal exposure to diazepam and other benzodiazepines (BDZ) has been found to result in a marked reduction of T-lymphocyte proliferation during postnatal development of rats. In search for pathogenic changes underlying this effect, we investigated the mitogen lipopolysaccharide (LPS) and concanavalin A (ConA) stimulated release of tumour necrosis factor (TNF)-alpha by mixed splenocytes of male offspring from Long Evans rats treated with 1.25 mg/kg per day diazepam from gestational day 14 to 20. In response to LPS, TNF-alpha release was found to be significantly lower in mixed splenocytes of two- and four-week-old treated than in control offspring. However, at eight weeks of age, prenatally diazepam-treated animals showed a significantly higher LPS-induced TNF-alpha release than control rats. Since monocytes/macrophages represent a major source of TNF-alpha, additional experiments were performed on purified spleen macrophages and lymphocytes stimulated with LPS. TNF-alpha release w...
Murine experimental meningitis models induced by either Escherichia coli LPS, live Streptococcus ... more Murine experimental meningitis models induced by either Escherichia coli LPS, live Streptococcus pneumoniae ,o rListeria mono- cytogenes were used to study the origin and potential function of soluble CD14 (sCD14) in the brain during bacterial meningitis. Whereas intracerebral infection caused only a minor and/or transient increase of sCD14 levels in the serum, dramatically elevated concentrations of sCD14 were detected in
The vascular and the nervous system are responsible for oxygen, nutrient, and information transfe... more The vascular and the nervous system are responsible for oxygen, nutrient, and information transfer and thereby constitute highly important communication systems in higher organisms. These functional similarities are reflected at the anatomical, cellular, and molecular levels, where common developmental principles and mutual crosstalks have evolved to coordinate their action. This resemblance of the two systems at different levels of complexity has been termed the "neurovascular link." Most of the evidence demonstrating neurovascular interactions derives from studies outside the CNS and from the CNS tissue of the retina. However, little is known about the specific properties of the neurovascular link in the brain. Here, we focus on regulatory effects of molecules involved in the neurovascular link on angiogenesis in the periphery and in the brain and distinguish between general and CNS-specific cues for angiogenesis. Moreover, we discuss the emerging molecular interactions of these angiogenic cues with the VEGF-VEGFR-Delta-like ligand 4 (Dll4)-Jagged-Notch pathway.
Intra-hippocampal injection of kainic acid (KA) in adult mice causes a focal lesion in the CA1 ar... more Intra-hippocampal injection of kainic acid (KA) in adult mice causes a focal lesion in the CA1 area and hilus of the dentate gyrus, as well as pronounced granule cell hypertrophy and dispersion. The lesion results in chronic focal seizures, with a two-week delay following KA-induced status epilepticus. Furthermore, seizures are preceded by infiltration of T lymphocytes into the lesioned tissue and of macrophage-like cells, strongly immunopositive for the monocyte marker F4/80, into the dentate gyrus, where they regulate granule cell dispersion and survival. Unexpectedly, depletion of CD4(+) and/or CD8(+) T lymphocytes by targeted gene deletion results in a marked shortening of the delay prior to seizure onset, suggesting a role of adaptive immunity in epileptogenesis (Zattoni et al. 2011, J. Neurosci. 31, 4037). Here, we investigated the specific role of adaptive immunity in this TLE model by adoptive i.v. transfer of immunopurified T cells in mutant mice lacking either CD4(+) T cel...
Glioblastoma are among the most angiogenic tumors. The molecular mechanisms that control blood ve... more Glioblastoma are among the most angiogenic tumors. The molecular mechanisms that control blood vessel formation by endothelial cells (EC) in glioblastoma remain incompletely understood. Transforming growth factor-β (TGF-β) is a key regulatory cytokine that has proinvasive and stemness-maintaining autocrine properties in glioblastoma and confers immunosuppression to the tumor microenvironment. Here we characterize potential pro- and anti-angiogenic activities of TGF-β in the context of glioblastoma in vitro, using human brain-derived microvascular endothelial cells (hCMEC/D3) and glioblastoma-derived endothelial cells (GMEC) as model systems. We find that TGF-β induces vascular endothelial growth factor (VEGF) and placental growth factor (PlGF) mRNA expression and protein release in a TGF-β receptor (TβR) II / activin-like kinase (ALK)-5-dependent manner under normoxia and hypoxia, defining potential indirect proangiogenic activity of TGF-β in glioblastoma. In parallel, exogenous TGF...
Transforming growth factor (TGF)-β is a central molecule maintaining the malignant phenotype of g... more Transforming growth factor (TGF)-β is a central molecule maintaining the malignant phenotype of glioblastoma. Anti-TGF-β strategies are currently being explored in early clinical trials. Yet, there is little contemporary data on the differential expression of TGF-β isoforms at the mRNA and protein level or TGF-β/Smad pathway activity in glioblastomas in vivo.Here we studied 64 newly diagnosed and 16 recurrent glioblastomas for the expression of TGF-β1-3, platelet-derived growth factor (PDGF)-B, and plasminogen activator inhibitor (PAI)-1 mRNA by RT-PCR and for the levels of TGF-β1-3 protein, phosphorylated Smad2 (pSmad2), pSmad1/5/8 and PAI-1 by immunohistochemistry.Among the TGF-β isoforms, TGF-β1 mRNA was the most, whereas TGF-β3 mRNA was the least abundant. TGF-β1-3 mRNA expression was strongly correlated, as was the expression of TGF-β1-3 mRNA, and of the TGF-β1-3 target genes, PDGF-B and PAI-1. TGF-β2 and TGF-β3 protein levels correlated well, whereas the comparison of the othe...
Targeting the oxygen stress response pathway is considered a promising strategy to exert antineop... more Targeting the oxygen stress response pathway is considered a promising strategy to exert antineoplastic activity in a broad spectrum of tumor types. Supporting this view, we summarize the mechanism of action of Taurolidine and Piperlongumine, two antineoplastic agents with strikingly broad tumor selectivity. Taurolidine enhances the oxidative stress (ROS) selectively in tumor cells. Its cytotoxicity for various tumor cells in vitro and in vivo, which includes tumor stem cells, is based on the induction of programmed cell death, largely via apoptosis but also necroptosis and autophagy. The redox-directed mechanism of action of Taurolidine is apparent from the finding that reducing agents e.g., N-acetylcysteine or glutathione impair its cytotoxicity, while its effectiveness is enhanced by agents which inhibit the cellular anti‑oxidant capacity. A similar redox-directed antineoplastic action is shown by Piperlongumine, a recently described experimental drug of plant origin. Taurolidine...
Human malignant gliomas arise from neural progenitor cells and/or dedifferentiated astrocytes. By... more Human malignant gliomas arise from neural progenitor cells and/or dedifferentiated astrocytes. By now, they are genetically so well characterized that several murine glioma models have emerged that faithfully reiterate the typical histological features of the disease. In experimental animals, only one or two elements of the growth factor/Ras, PI3K/PTEN/PKB, p53/ARF/HDM2, and p16/Rb/cyclinD/CDK4 pathways are targeted. In human gliomas, many additional genes and pathways are targeted due to a most severe mutator phenotype that leads to the accumulation of countless epigenetic and genetic alterations. Changes that convey a growth advantage are selected for, leading to overgrowth of precursor cell populations with increasingly malignant tumor cell clones. While murine models represent a powerful tool for elucidating the role of genetic pathways, mechanisms of response and resistance to new therapeutic agents might be fundamentally different due to the high degree of genomic instability ...
Regulation of epithelial and endothelial permeability is essential for proper function of compart... more Regulation of epithelial and endothelial permeability is essential for proper function of compartmentalized organisms, and tyrosine phosphorylation plays an important role in this process. We analyzed the impact of protein tyrosine phosphatase (PTP) inhibition on the structure of endothelial junctional proteins. In human umbilical vein endothelial cells (HUVECs) the PTP inhibitors phenylarsine oxide (PAO) and pervanadate induced proteolysis of the tight junction protein occludin. Occludin proteolysis was inhibited by the metalloproteinase inhibitor 1,10-phenanthroline (PHEN), but not by inhibitors against other types of proteases. The junctional proteins ZO-1, cadherin and beta-catenin were not cleaved. Under conditions of occludin proteolysis, PAO treatment elevated permeability for FITC-dextran. Simultaneous incubation of HUVECs with PAO and PHEN inhibited the rise in permeability by more than 60%. PAO treatment lead to progressive disappearance of occludin from the cell periphery...
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Papers by Karl Frei