RESUMEN
Miscarriage is the most common complication in early pregnancy. It was recently reported in mice that miscarriage can be prevented through the administration of niacin. We conducted a prospective, exploratory pilot study involving 24 women who were less than 14 weeks pregnant. Neither niacin intake (P = 0.24) nor urinary vitamin B3 measured as the 1-methyl-5-carboxylamide-2-pyridone/N-1-methylnicotinamide (2-pyr/MNA) ratio (P = 1.00) predicted miscarriage. However, the difference in mean 2-pyr/MNA ratios between women who miscarried and controls suggests there may be a threshold niacin level protective in miscarriage prevention warranting further investigation.
Asunto(s)
Aborto Espontáneo , Niacina , Animales , Femenino , Humanos , Ratones , Niacinamida , Proyectos Piloto , Embarazo , Primer Trimestre del Embarazo , Estudios ProspectivosRESUMEN
Glucocorticoids are critical components of combination chemotherapy regimens in pediatric acute lymphoblastic leukemia (ALL). The proapoptotic BIM protein is an important mediator of glucocorticoid-induced apoptosis in normal and malignant lymphocytes, whereas the antiapoptotic BCL2 confers resistance. The signaling pathways regulating BIM and BCL2 expression in glucocorticoid-treated lymphoid cells remain unclear. In this study, pediatric ALL patient-derived xenografts (PDXs) inherently sensitive or resistant to glucocorticoids were exposed to dexamethasone in vivo. Microarray analysis showed that KLF13 and MYB gene expression changes were significantly greater in dexamethasone-sensitive than -resistant PDXs. Chromatin immunoprecipitation (ChIP) analysis detected glucocorticoid receptor (GR) binding at the KLF13 promoter to trigger KLF13 expression only in sensitive PDXs. Next, KLF13 bound to the MYB promoter, deactivating MYB expression only in sensitive PDXs. Sustained MYB expression in resistant PDXs resulted in maintenance of BCL2 expression and inhibition of apoptosis. ChIP sequencing analysis revealed a novel GR binding site in a BIM intronic region (IGR) that was engaged only in dexamethasone-sensitive PDXs. The absence of GR binding at the BIM IGR was associated with BIM silencing and dexamethasone resistance. This study has identified novel mechanisms of opposing BCL2 and BIM gene regulation that control glucocorticoid-induced apoptosis in pediatric ALL cells in vivo.