RESUMEN
DNA methylation might have a significant role in preventing normal differentiation in pediatric cancers. We used a genomewide method for detecting regions of CpG methylation on the basis of the increased melting temperature of methylated DNA, termed denaturation analysis of methylation differences (DAMD). Using the DAMD assay, we find common regions of cancer-specific methylation changes in primary medulloblastomas in critical developmental regulatory pathways, including Sonic hedgehog (Shh), Wingless (Wnt), retinoic acid receptor (RAR), and bone morphogenetic protein (BMP). One of the commonly methylated loci is the PTCH1-1C promoter, a negative regulator of the Shh pathway that is methylated in both primary patient samples and human medulloblastoma cell lines. Treatment with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine (5-aza-dC) increases the expression of PTCH1 and other methylated loci. Whereas genetic mutations in PTCH1 have previously been shown to lead to medulloblastoma, our study indicates that epigenetic silencing of PTCH1, and other critical developmental loci, by DNA methylation is a fundamental process of pediatric medulloblastoma formation. This finding warrants strong consideration for DNA demethylating agents in future clinical trials for children with this disease.
Asunto(s)
Metilación de ADN , Genes del Desarrollo , Meduloblastoma/genética , Línea Celular Tumoral , Niño , Islas de CpG , Epigénesis Genética , Silenciador del Gen , Humanos , Análisis por Micromatrices , Receptores Patched , Receptor Patched-1 , Regiones Promotoras Genéticas , Receptores de Superficie Celular/genética , Receptores de Superficie Celular/metabolismoRESUMEN
Understanding costs associated with breastfeeding is critical to developing maximally effective policy to support breastfeeding by addressing financial barriers. Breastfeeding is not without cost; direct costs include those of equipment, modified nutritional intake, and time (opportunity cost). Breastfeeding need not require more equipment than formula feeding, though maternal equipment use varies by maternal preference. Meeting increased nutritional demands requires increased spending on food and potentially dietary supplementation, the marginal cost of which depends on a mother's baseline diet. The opportunity cost of the three to four hours per day breastfeeding demands may be prohibitively high, particularly to low-income workers. These costs are relatively highest for low-income individuals, a group disproportionately comprising racial and ethnic minorities, and who demonstrate lower rates of breastfeeding than their white and higher-income peers. Acknowledging and addressing these costs and their regressive nature represents a critical component of effective breastfeeding policy and promotion.
Asunto(s)
Lactancia Materna , Pobreza , Femenino , Humanos , Lactante , RentaRESUMEN
Rhabdomyosarcoma is the most common soft-tissue sarcoma in children. While cytogenetic abnormalities have been well characterized in this disease, aberrant epigenetic events such as DNA hypermethylation have not been described in genome-wide studies. We have analyzed the methylation status of 25,500 promoters in normal skeletal muscle, and in cell lines and tumor samples of embryonal and alveolar rhabdomyosarcoma from pediatric patients. We identified over 1,900 CpG islands that are hypermethylated in rhabdomyosarcomas relative to skeletal muscle. Genes involved in tissue development, differentiation, and oncogenesis such as DNAJA4, HES5, IRX1, BMP8A, GATA4, GATA6, ALX3, and P4HTM were hypermethylated in both RMS cell lines and primary samples, implicating aberrant DNA methylation in the pathogenesis of rhabdomyosarcoma. Furthermore, cluster analysis revealed embryonal and alveolar subtypes had distinct DNA methylation patterns, with the alveolar subtype being enriched in DNA hypermethylation of polycomb target genes. These results suggest that DNA methylation signatures may aid in the diagnosis and risk stratification of pediatric rhabdomyosarcoma and help identify new targets for therapy.
Asunto(s)
Metilación de ADN , Rabdomiosarcoma Alveolar/genética , Rabdomiosarcoma Embrionario/genética , Adolescente , Línea Celular Tumoral , Niño , Preescolar , Análisis por Conglomerados , Islas de CpG , Femenino , Sitios Genéticos , Genoma Humano , Proteínas del Choque Térmico HSP40/genética , Proteínas del Choque Térmico HSP40/metabolismo , Proteínas de Homeodominio/genética , Proteínas de Homeodominio/metabolismo , Humanos , Subunidad alfa del Factor 1 Inducible por Hipoxia/genética , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Masculino , Músculo Esquelético/metabolismo , Músculo Esquelético/patología , Regiones Promotoras Genéticas , Rabdomiosarcoma Alveolar/metabolismo , Rabdomiosarcoma Alveolar/patología , Rabdomiosarcoma Embrionario/metabolismo , Rabdomiosarcoma Embrionario/patología , Análisis de Secuencia de ADN/métodos , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Adulto JovenRESUMEN
Prior studies of the DM1 locus have shown that the CTG repeats are a component of a CTCF-dependent insulator element and that repeat expansion results in conversion of the region to heterochromatin. We now show that the DM1 insulator is maintained in a local heterochromatin context: an antisense transcript emanating from the adjacent SIX5 regulatory region extends into the insulator element and is converted into 21 nucleotide (nt) fragments with associated regional histone H3 lysine 9 (H3-K9) methylation and HP1gamma recruitment that is embedded within a region of euchromatin-associated H3 lysine 4 (H3-K4) methylation. CTCF restricts the extent of the antisense RNA at the wild-type (wt) DM1 locus and constrains the H3-K9 methylation to the nucleosome associated with the CTG repeat, whereas the expanded allele in congenital DM1 is associated with loss of CTCF binding, spread of heterochromatin, and regional CpG methylation.