Melatonin-induced methylation of the ABCG2/BCRP promoter as a novel mechanism to overcome multidrug resistance in brain tumour stem cells.

BACKGROUND: Current evidence indicates that a stem cell-like sub-population within malignant glioblastomas, that overexpress members of the adenosine triphosphate-binding cassette (ABC) family transporters, is responsible for multidrug resistance and tumour relapse. Eradication of the brain tumour stem cell (BTSC) compartment is therefore essential to achieve a stable and long-lasting remission. METHODS: Melatonin actions were analysed by viability cell assays, flow cytometry, quantitative PCR for mRNA expression, western blot for protein expression and quantitative and qualitative promoter methylation methods. RESULTS: Combinations of melatonin and chemotherapeutic drugs (including temozolomide, current treatment for malignant gliomas) have a synergistic toxic effect on BTSCs and A172 malignant glioma cells. This effect is correlated with a downregulation of the expression and function of the ABC transporter ABCG2/BCRP. Melatonin increased the methylation levels of the ABCG2/BCRP promoter and the effects on ABCG2/BCRP expression and function were prevented by preincubation with a DNA methyltransferase inhibitor. CONCLUSION: Our results point out a possible relationship between the downregulation of ABCG2/BCRP function and the synergistic toxic effect of melatonin and chemotherapeutic drugs. Melatonin could be a promising candidate to overcome multidrug resistance in the treatment of glioblastomas, and thus improve the efficiency of current therapies.

Fas/Fas ligand regulation mediates cell death in human Ewing's sarcoma cells treated with melatonin.

BACKGROUND: Despite recent advances in cancer therapy, the 5-year survival rate for Ewing's sarcoma is still very low, and new therapeutic approaches are necessary. It was found previously that melatonin induces cell death in the Ewing's sarcoma cell line, SK-N-MC, by activating the extrinsic apoptotic pathway. METHODS: Melatonin actions were analysed by metabolic viability/survival cell assays, flow cytometry, quantitative PCR for mRNA expression, western blot for protein activation/expression and electrophoretic mobility shift assay for transcription factor activation. RESULTS: Melatonin increases the expression of Fas and its ligand Fas L, this increase being responsible for cell death induced by the indolamine. Melatonin also produces a transient increase in intracellular oxidants and activation of the redox-regulated transcription factor Nuclear factor-kappaB. Inhibition of such activation prevents cell death and Fas/Fas L upregulation. Cytotoxic effect and Fas/Fas L regulation occur in all Ewing's cell lines studied, and do not occur in the other tumour cell lines studied where melatonin does not induce cell death. CONCLUSION: Our data offers new insights in the study of alternative therapeutic strategies in the treatment of Ewing's sarcoma. Further attention deserves to be given to the differences in the cellular biology of sensitive tumours that could explain the cytotoxic effect of melatonin and the increase in the level of free radicals caused by this molecule, in particular cancer types.

[The Spanish version of the Newcastle Asthma Knowledge Questionnaire for parents of children with asthma (NAKQ). Transcultural adaptation and reliability analysis]. / Versión española del NAKQ. Adaptación transcultural y análisis de fiabilidad y validez.

INTRODUCTION: The Newcastle Asthma Knowledge Questionnaire for parents of children with asthma (NAKQ) has proven to be a valid instrument for asthma knowledge assessment of patients and their parents. The widespread use of the SRS-22 in non-English-speaking countries requires its transcultural adaptation. Our objective was to obtain a version of the NAKQ questionnaire adapted to Spanish and to analyze its validity and reliability. MATERIAL AND METHODS: The Spanish version was obtained by using the forward/back-translation method with expert, bilingual translators. The questionnaire was administered to 157 parents with high knowledge (n = 78) and low knowledge (n = 79) of asthma. The differences in the number of answers between both groups were analyzed with the chi(2) test. Internal consistency was determined with Cronbach's alpha coefficient and test-retest reliability with the tau-b of Kendall correlation coefficient, and kappa statistics. RESULTS: At the end of the process, 23 of the 31 items were classified as of total equivalence and eight ase of moderate equivalence. The mean score of parents high knowledge was 23 +/- 2.94 and the mean score of parents low knowledge was 16.84 +/- 2.56. The difference between the two groups was statistically significant (p < 0.001). The overall Cronbach's alpha coefficient of the questionnaire was 0.72, the Kendall's tau-b 0,8573 was significant (p = 0.01) and the kappa index showed good or very good consistency in more than half of the items. CONCLUSIONS: The Spanish version of the NAKQ has proven to be acceptable and culturally equivalent to the original version and it has a good degree of consistency, validity and reliability.

Versión española del NAKQ. Adaptación transcultural y análisis de fiabilidad y validez / The Spanish version of the Newcastle Asthma Knowledge Questionnaire for parents of children with asthma (NAKQ). Transcultural adaptation and reliability analysis

Introducción: el Newcastle Asthma Knowledge Questionnaire (NAKQ) ha probado ser un instrumento válido para evaluar los conocimientos sobre asma en pacientes y sus padres. El empleo extendido del NAKQ en países de habla no inglesa requiere su adaptación transcultural. Nuestro objetivo fue obtener una versión adaptada del cuestionario NAKQ al castellano y analizar su fiabilidad y validez.Material y métodos: para obtener la versión en español se ha seguido la metodología de traducción directa e inversa con traductores expertos bilingües. El cuestionario se administró a 157 padres/madres con gran conocimiento (n=78) y escaso conocimiento (n=79) de asma. Las diferencias en el número de respuestas entre ambos grupos se analizaron con la prueba de la χ2. La consistencia interna del cuestionario se determinó con el coeficiente alfa de Cronbach y la reproducibilidad test-retest, con el coeficiente de correlación tau-b de Kendall y el índice kappa.Resultados: al final del proceso, 23 de los 31 ítems fueron clasificados como de equivalencia total y 8, de equivalencia moderada. La puntuación media de los padres con gran conocimiento fue 23±2,94 y de los de escaso conocimiento fue 16,84±2,56. La diferencia entre los dos grupos fue significativa (p<0,001). El coeficiente global de Cronbach del cuestionario fue 0,72, la tau-b de Kendall fue 0,8573, con significación (p=0,01) y el índice kappa mostró en más de la mitad de los ítems buena o muy buena reproducibilidad.Conclusiones: la versión española del NAKQ es aceptable y equivalente culturalmente a la versión original y tiene un buen grado de fiabilidad, validez y reproducibilidad(AU)

Introduction: The Newcastle Asthma Knowledge Questionnaire for parents of children with asthma (NAKQ) has proven to be a valid instrument for asthma knowledge assessment of patients and their parents. The widespread use of the SRS-22 in non-English-speaking countries requires its transcultural adaptation. Our objective was to obtain a version of the NAKQ questionnaire adapted to Spanish and to analyze its validity and reliability. Material and methods: The Spanish version was obtained by using the forward/back-translation method with expert, bilingual translators. The questionnaire was administered to 157 parents with high knowledge (n=78) and low knowledge (n=79) of asthma. The differences in the number of answers between both groups were analyzed with the χ2 test. Internal consistency was determined with Cronbach’s alpha coefficient and test–retest reliability with the tau-b of Kendall correlation coefficient, and kappa statistics. Results: At the end of the process, 23 of the 31 items were classified as of total equivalence and eight ase of moderate equivalence. The mean score of parents high knowledge was 23±2.94 and the mean score of parents low knowledge was 16.84±2.56. The difference between the two groups was statistically significant (p<0.001). The overall Cronbach’s alpha coefficient of the questionnaire was 0.72, the Kendall’s tau-b 0,8573 was significant (p=0.01) and the kappa index showed good or very good consistency in more than half of the items. Conclusions: The Spanish version of the NAKQ has proven to be acceptable and culturally equivalent to the original version and it has a good degree of consistency, validity and reliability (AU)