Targeting sphingolipid metabolism with the sphingosine kinase inhibitor SKI-II overcomes hypoxia-induced chemotherapy resistance in glioblastoma cells: effects on cell death, self-renewal, and invasion.

BACKGROUND: Glioblastoma patients commonly develop resistance to temozolomide chemotherapy. Hypoxia, which supports chemotherapy resistance, favors the expansion of glioblastoma stem cells (GSC), contributing to tumor relapse. Because of a deregulated sphingolipid metabolism, glioblastoma tissues contain high levels of the pro-survival sphingosine-1-phosphate and low levels of the pro-apoptotic ceramide. The latter can be metabolized to sphingosine-1-phosphate by sphingosine kinase (SK) 1 that is overexpressed in glioblastoma. The small molecule SKI-II inhibits SK and dihydroceramide desaturase 1, which converts dihydroceramide to ceramide. We previously reported that SKI-II combined with temozolomide induces caspase-dependent cell death, preceded by dihydrosphingolipids accumulation and autophagy in normoxia. In the present study, we investigated the effects of a low-dose combination of temozolomide and SKI-II under normoxia and hypoxia in glioblastoma cells and patient-derived GCSs. METHODS: Drug synergism was analyzed with the Chou-Talalay Combination Index method. Dose-effect curves of each drug were determined with the Sulforhodamine B colorimetric assay. Cell death mechanisms and autophagy were analyzed by immunofluorescence, flow cytometry and western blot; sphingolipid metabolism alterations by mass spectrometry and gene expression analysis. GSCs self-renewal capacity was determined using extreme limiting dilution assays and invasion of glioblastoma cells using a 3D spheroid model. RESULTS: Temozolomide resistance of glioblastoma cells was increased under hypoxia. However, combination of temozolomide (48 µM) with SKI-II (2.66 µM) synergistically inhibited glioblastoma cell growth and potentiated glioblastoma cell death relative to single treatments under hypoxia. This low-dose combination did not induce dihydrosphingolipids accumulation, but a decrease in ceramide and its metabolites. It induced oxidative and endoplasmic reticulum stress and triggered caspase-independent cell death. It impaired the self-renewal capacity of temozolomide-resistant GSCs, especially under hypoxia. Furthermore, it decreased invasion of glioblastoma cell spheroids. CONCLUSIONS: This in vitro study provides novel insights on the links between sphingolipid metabolism and invasion, a hallmark of cancer, and cancer stem cells, key drivers of cancer. It demonstrates the therapeutic potential of approaches that combine modulation of sphingolipid metabolism with first-line agent temozolomide in overcoming tumor growth and relapse by reducing hypoxia-induced resistance to chemotherapy and by targeting both differentiated and stem glioblastoma cells.

Intervenções de Enfermagem na prevenção de extubação não programada em recém-nascidos: bundle de boas práticas / Nursing interventions for the prevention of non scheduled extubation in newborns: bundle of good practice

OBJETIVOS: identificar o conhecimento da equipe de Enfermagem acerca da extubação não programada (ENP), os fatores relacionados, as complicações/agravos e as intervenções de Enfermagem como medidas preventivas juntos ao recém-nascido de risco. METODOLOGIA: Pesquisa descritiva, qualitativa realizada na Unidade de Terapia Intensiva Neonatal de um hospital pediátrico de Fortaleza-Ceará, no período de julho a setembro de 2018. RESULTADOS: Evidenciou-se a necessidade de pactuação sobre o conceito de ENP entre a equipe. Dentre os principais fatores relacionados teve-se: excesso de manuseio e ausência de comunicação efetiva na equipe. Como intervenções preventivas ressaltou-se o posicionamento do RN e a fixação adequada do tubo. CONCLUSÃO: a equipe de enfermagem tem preciosos saberes e intervenções que puderam ser visualizados como medidas de boas práticas na prevenção das ENP para construção de um Bundle. (AU)

Objective: To identify the knowledge of the Nursing team about non-programmed extubation (ENP), related factors, complications/injuries and Nursing interventions as preventive measures together with the newborn at risk. Methodology: Descriptive and qualitative research performed at the Neonatal Intensive Care Unit of a pediatric hospital in Fortaleza, Ceará, from July to September, 2018. Results: The need for agreement on the concept of PNS among the team was evidenced. Among the main related factors were: excessive handling and lack of effective communication in the team. As preventive interventions, the positioning of the newborn and adequate tube fixation were emphasized. Conclusion: the nursing team has valuable knowledge and interventions that could be visualized as measures of good practices in the prevention of NPS for the construction of a Bundle. (AU)

Objetivo: identificar el conocimiento del equipo de Enfermería acerca de la extubación no programada (ENP), los factores relacionados, las complicaciones / agravios y las intervenciones de Enfermería como medidas preventivas junto al recién nacido de riesgo. Metodologia: Investigación descriptiva, cualitativa realizada en la Unidad de Terapia Intensiva Neonatal de un hospital pediátrico de Fortaleza-Ceará, en el período de julio a septiembre de 2018. Resultados: Se evidenció la necesidad de pactación sobre el concepto de ENP entre el equipo. Entre los principales factores relacionados se tuvo: exceso de manejo y ausencia de comunicación efectiva en el equipo. Como intervenciones preventivas se resaltó el posicionamiento del RN y la fijación adecuada del tubo. Conclusión: el equipo de enfermería tiene preciosos saberes e intervenciones que pudieron ser visualizados como medidas de buenas prácticas en la prevención de las ENP para la construcción de un Bundle. (AU)