An Enzyme- and Serum-free Neural Stem Cell Culture Model for EMT Investigation Suited for Drug Discovery

Epithelial to mesenchymal transition (EMT) describes the process of epithelium transdifferentiating into mesenchyme. EMT is a fundamental process during ...

Klinikum Idar-Oberstein

Recently, several studies proposed a physiological role for the cellular prion protein (PrP(c)) in defense against oxidative stress. Since the pathogenesis of prion disease necessarily involves a disturbance of PrP(c) homeostasis, we hypothesized that such diseases would be associated with concomitant disturbances in oxidative balance. In support of such a notion, in this study we show increased oxidative damage to nucleic acids in affected brains of patients with Creutzfeldt-Jakob disease. These data suggest that damage by free radicals is a likely cause for neurodegeneration in human prion disease, and antioxidants are a potential therapy for these disorders. Further, our data support the hypothesis that loss of the anti-oxidant function of PrP(c) plays a key role in the pathogenesis of these disorders.

Oxidative damage to nucleic acids in human prion disease.

The central event in the neuropathological process of prion diseases (PrD) is the accumulation of abnormal prion protein accompanied by severe neuronal loss. Despite the infectious nature of these diseases, no prominent immune response has been detected yet. However, recent studies have shown that complement, a component of the innate immune system, is involved in the early pathogenesis of experimental prion infection. Here we demonstrate, in the diseased human brains, the presence of active compounds of the complement system, like C1q and C3b, in extracellular disease-associated prion protein deposits and the membrane attack complex in neurons. The neuronal localization of the membrane attack complex correlates well with the severity of disease-specific pathology and TUNEL labeling of neurons, irrespective of genotype or molecular phenotype of human prion diseases.

Complement activation in human prion disease.

Prion diseases are characterized by the accumulation of diffuse and aggregated plaques of protease-resistant prion protein (PrP) in the brains of affected individuals and animals. Whereas prion diseases in animals appear to be almost exclusively transmitted by infection, human prion diseases most often occur sporadically and, to a lesser extent, by inheritance or infection. In the sporadic cases (sporadic Creutzfeld-Jakob disease, sCJD), PrP-containing plaques are infrequent, whereas in transmitted (variant CJD) and inherited (Gerstmann-Straussler-Scheinker Syndrome) cases, plaques are a usual feature. In the current study, representative cases from each of the classes of human prion disease were analyzed for the presence of markers of oxidative damage that have been found in other neurodegenerative diseases. Interestingly, we found that the pattern of deposition of PrP, amyloid-beta, and redox active metals was distinct for the various prion diseases. Whereas 8-hydroxyguanosine has been shown to be increased in sCJD, and inducible NOS is increased in scrapie-infected mice, well-studied markers of oxidative damage that accumulate in the lesions of other neurodegenerative diseases (such as Alzheimer's disease, progressive supranuclear palsy, and Parkinson's disease), such as heme oxygenase-1 and lipid peroxidation, were not found around PrP deposits or in vulnerable neurons. These findings suggest an important distinction in prion-related oxidative stress, indicating that different neurodegenerative pathways are involved in different prion diseases.

Redox metals and oxidative abnormalities in human prion diseases.

Self-renewal and differentiation of CNS stem cells are regulated by still poorly understood cell-cell interactions. Notch is a well-known cell surface protein that can promote both cell cycle progression and mitotic arrest but the molecular mechanism controlling these opposite effects is unknown. Here we demonstrate that, in CNS stem cells, the level of active Notch1 determines the cellular response. Specifically, low levels of the active form of Notch1 promote proliferation whereas high levels lead to growth arrest. Here we provide the first evidence that Notch effects on proliferation and differentiation are a function of dose, and propose a hypothesis on how oncogenes may also act as tumor suppressors.

Notch controls proliferation and differentiation of stem cells in a dose-dependent manner.

Signal transducer and activator of transcription protein 3 (STAT3) is a regulator of central nervous system (CNS) development and a promising therapeutic target in human cancers. Activation of STAT3 promotes oncogenesis in a variety of tissues, but knowledge of its role in glioblastoma is still limited. Recent results indicate that STAT3 acts as a tumor suppressor or an oncogene depending upon the genetic background of the tumor. Here we immunohistochemically assessed Y705-phosphorylated STAT3 (pY705-STAT3) in formalin-fixed, paraffin-embedded specimens of 111 patients with supratentorial glioblastomas and 25 patients with supratentorial grade III gliomas. We found that glioblastoma patients with high or very high numbers of pY705-STAT3-positive tumor cells had significantly shorter overall survival than those with no or low numbers (P = 0.001, Cox regression). Interestingly the proportion of grade III glioma cases with high or very high numbers of pY705-STAT3-positive tumor cells was similar to that in glioblastoma. Our findings provide evidence that activation of STAT3 by Y705 phosphorylation is linked with clinically more aggressive behavior in glioblastomas, but is most likely not associated with tumor progression of grade III gliomas. In sum, our results suggest that STAT3 inhibition should be considered as a therapeutic approach in malignant gliomas.

STAT3 tyrosine phosphorylation influences survival in glioblastoma.

Gliomas are the most common primary brain tumours. Several independent studies have shown that isocitrate dehydrogenase 1 (IDH1) mutation in diffuse gliomas is associated with a more favourable patient outcome. The aim of this study was to evaluate the prognostic relevance of an antibody specifically detecting the R132H point mutation of IDH1 in tissue sections in a large series of human gliomas. Surgical specimens of 220 consecutive patients with infiltrative low and high-grade gliomas were included in this retrospective study. In multivariate analysis, IDH expression did not reach significance (p = 0.122) in regard to prognosis, in contrast to WHO grade and age at time of surgery (p < 0.001, Cox regression). A significant correlation of p53 expression to mutated IDH1 and histological grading and an inverse correlation to truncated EGFR expression were observed (p < 0.001, Mann-Whitney test). In sum, our results indicate that IDHR132H mutation correlates significantly with p53 and inversely with EGFR mutations. Further studies should investigate whether these correlations reflect involvement of these three molecules in a common signalling pathway.

Expression of mutated isocitrate dehydrogenase-1 in gliomas is associated with p53 and EGFR expression.

Animal studies have shown cooperative contribution of the Ras/Raf/MAPK and PI3K/Akt/mTOR signaling pathways in glioblastoma formation. However, this joint action has not yet been confirmed in human studies.

Additive effect on survival of Raf kinase inhibitor protein and signal transducer and activator of transcription 3 in high-grade glioma.

Recently, isocitrate dehydrogenase 1 (IDH1) was identified as a major participant in glioma pathogenesis. At present, the enzymatic activity of the protein has been the main topic in investigating its physiological function, but its signaling pathway allocation was unsuccessful. Interestingly, proteins regulated by phosphoinositide 3-kinase (PI3K)/Akt signaling, are among the top downregulated genes in gliomas associated with high percentage of IDH1 and IDH2 mutations. The aim of this study was to investigate a hypothetical relation between IDH1 and PI3K signaling.

Mutant IDH1 inhibits PI3K/Akt signaling in human glioma.

Sacroiliac joint (SIJ) pain affects older adults with a prevalence of up to 20% among patients with chronic low back pain. While pain medication, joint blocks and denervation procedures achieve pain relief in most patients, some cases fail to improve. Our goal was to determine the effectiveness of SIJ peripheral nerve stimulation in patients with severe conservative therapy-refractory SIJ pain.

Technical Note: Treatment of Sacroiliac Joint Pain with Peripheral Nerve Stimulation.

The chemokine receptor CXCR7 is found on glioma cells and glioma-associated vessels and dependent upon its localisation on tumour or endothelial cells the CXCR7 receptor can mediate glioma cell invasion and tumour angiogenesis. Its expression predicts survival in several types of cancers.

Marin Guentchev

Department of Neurosurgery

Klinikum Idar-Oberstein

An Enzyme- and Serum-free Neural Stem Cell Culture Model for EMT Investigation Suited for Drug Discovery

Marin Guentchev

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Neurosurgery

Klinikum Idar-Oberstein

An Enzyme- and Serum-free Neural Stem Cell Culture Model for EMT Investigation Suited for Drug Discovery

Department of Neurosurgery