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  • 1
    ISSN: 0942-0940
    Keywords: Keywords: Vitamin D; ceramide; sphingomyelin; brain tumours.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary  1α,25-dihydroxyvitamin D3 was previously shown to induce cell death in brain tumour cell lines when added to the medium at micromolar concentration. In this paper we show that Cholecalciferol, a poor ligand of the vitamin D receptor, also induces cell death of HU197 human glioblastoma cell line and early passages cultures derived from a recurrent human glioblastoma. This finding suggests that the effects of vitamin D metabolites on brain tumour cells are at least partially independent from the activation of the classic nuclear receptor pathway. Vitamin D metabolites have been shown to activate the sphingomyelin pathway inducing an increase in cellular ceramide concentration. We determined the levels of sphingomyelin ceramide and ganglioside GD3 in Hu197 cells after treatment with cholecalciferol. A significant increase in ceramide concentration and a proportional decrease in sphingomyelin was already present after 6 hours of cholecalciferol treatment when no morphological changes were visible in the cultures. Treatment with ceramides (N-acetyl-sphingosine or natural ceramide from bovine brain) of the same cells also induces cell death. Similarly, treatment of the same cells with bacterial Sphingomyelinase also results in cell death. The demonstration of an increase in intracellular ceramide after cholecalciferol treatment and the ability of ceramide to induce cell death suggest that the sphingomyelin pathway may be implicated in the effect of vitamin D metabolites on human glioblastoma cells. Inhibition of ceramide biosynthesis by fumonisin B1 treatment did not alter the dose response curve of HU197 cells to cholecalciferol. Insensitivity to fumonisin B1 together with a decrease in sphingomyelin content after cholecalciferol treatment indicate that activation of sphingomyelinase should be responsible for the increase in intracellular ceramide concentration.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 133 (1995), S. 184-190 
    ISSN: 0942-0940
    Keywords: Glioblastoma ; retinoic acid ; vitamin D ; cell death
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The biological significance of vitamin D receptors expressed by glioblastoma and other glial tumours is still unclear. In an effort to clarify this issue we studied the effects of increasing concentrations of 25-dihydroxyvitamin D3 and its metabolite 1 α, 25-dihydroxyvitamin D3 on two human glioblastoma cell lines. Both substances were capable of inducing a significant (〉 50%) reduction in growth of the two glioblastoma cell lines at dosages over 5 μM. When the HU 70 cell line was treated by increasing dilutions of 25-dihydroxyvitamin D3 combined with 1 μM all trans-retinoic acid, significant inhibition was apparent even after addition of 25-dihydroxyvitamin D3 in the nanomolar range. Reduction of growth index was mainly due to induced cell death. Our results providein vitro evidence that vitamin D metabolites alone or in combination with retinoids may be potentially useful agents in the differentiation therapy of human malignant gliomas.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1433-0350
    Keywords: Medulloblastoma ; Radiotherapy ; Chemotherapy ; Children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Between 1985 and 1989, 38 children with newly diagnosed medulloblastoma entered our therapeutic protocol. After surgery and postoperative staging assessments, patients were assigned to risk groups. Eleven with “standard-risk” (SR) tumors were treated with radiation therapy alone, while 27 with “high-risk” (HR) tumors received radiation therapy plus adjuvant chemotherapy with vincristine, methotrexate, VM-26, and 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU). After a minimum follow-up of 5 years (range 5–9 years) 21/38 children had developed a recurrence or progression of their disease and 19/38 patients had died. Five-year event-free survival rates and 5-year total survival rates for all 38 patients were 47.4% and 50% respectively. The event-free survival rates at 5 years for SR and HR patients separately were 27.3% and 55.6%, respectively. The corresponding 5-year total survival rates were 27.3% and 59.3%. The differences were not statistically significant. Univariate analysis showed age at diagnosis to be the most important prognostic factor. Infants aged 5 years or less had a significantly shorter event-free survival time than older patients (P=0.00897). Similar effects were found when total survival time was considered. There were significant differences in outcome in patients receiving different doses of radiation, suggesting a dose-response relationship. A Cox stepwise multivariate analysis showed age at diagnosis as the only independent prognostic factor. Variables relating to treatment entered the model, suggesting that chemotherapy could play an important role in determining outcome.
    Type of Medium: Electronic Resource
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