RESUMEN
Neuroblastoma is a paediatric malignancy that typically arises in early childhood, and is derived from the developing sympathetic nervous system. Clinical phenotypes range from localized tumours with excellent outcomes to widely metastatic disease in which long-term survival is approximately 40% despite intensive therapy. A previous genome-wide association study identified common polymorphisms at the LMO1 gene locus that are highly associated with neuroblastoma susceptibility and oncogenic addiction to LMO1 in the tumour cells. Here we investigate the causal DNA variant at this locus and the mechanism by which it leads to neuroblastoma tumorigenesis. We first imputed all possible genotypes across the LMO1 locus and then mapped highly associated single nucleotide polymorphism (SNPs) to areas of chromatin accessibility, evolutionary conservation and transcription factor binding sites. We show that SNP rs2168101 G>T is the most highly associated variant (combined P = 7.47 × 10(-29), odds ratio 0.65, 95% confidence interval 0.60-0.70), and resides in a super-enhancer defined by extensive acetylation of histone H3 lysine 27 within the first intron of LMO1. The ancestral G allele that is associated with tumour formation resides in a conserved GATA transcription factor binding motif. We show that the newly evolved protective TATA allele is associated with decreased total LMO1 expression (P = 0.028) in neuroblastoma primary tumours, and ablates GATA3 binding (P < 0.0001). We demonstrate allelic imbalance favouring the G-containing strand in tumours heterozygous for this SNP, as demonstrated both by RNA sequencing (P < 0.0001) and reporter assays (P = 0.002). These findings indicate that a recently evolved polymorphism within a super-enhancer element in the first intron of LMO1 influences neuroblastoma susceptibility through differential GATA transcription factor binding and direct modulation of LMO1 expression in cis, and this leads to an oncogenic dependency in tumour cells.
Asunto(s)
Proteínas de Unión al ADN/genética , Elementos de Facilitación Genéticos/genética , Predisposición Genética a la Enfermedad/genética , Proteínas con Dominio LIM/genética , Neuroblastoma/genética , Polimorfismo de Nucleótido Simple/genética , Factores de Transcripción/genética , Acetilación , Alelos , Desequilibrio Alélico , Sitios de Unión , Epigenómica , Factor de Transcripción GATA3/metabolismo , Regulación Neoplásica de la Expresión Génica/genética , Estudio de Asociación del Genoma Completo , Genotipo , Histonas/química , Histonas/metabolismo , Humanos , Intrones/genética , Lisina/metabolismo , Especificidad de Órganos , Reproducibilidad de los ResultadosRESUMEN
Shoulder arthroscopy is the second most common orthopaedic procedure. Diagnostic arthroscopy of the shoulder requires an efficient and reproducible technique. In this Technical Note, we describe a step-wise approach to diagnostic arthroscopy of the shoulder. This technique is performed using a posterior viewing portal. It can be performed from the beach chair or the lateral decubitus position. This technique uses a 2-circle approach: the surgeon first evaluates the glenoid aspect of the joint space, followed by the humeral aspect of the joint space. This method ensures a complete and consistent evaluation of the glenohumeral joint.