Co-regulated expression of HAND2 and DEIN by a bidirectional promoter with asymmetrical activity in neuroblastoma

<p>Abstract</p> <p>Background</p> <p><it>HAND2</it>, a key regulator for the development of the sympathetic nervous system, is located on chromosome 4q33 in a head-to-head orientation with <it>DEIN</it>, a recently identified novel gene with stage specific expression in primary neuroblastoma (NB). Both genes are expressed in primary NB as well as most NB cell lines and are separated by a genomic sequence of 228 bp. The similar expression profile of both genes suggests a common transcriptional regulation mediated by a bidirectional promoter.</p> <p>Results</p> <p>Northern Blot analysis of <it>DEIN </it>and <it>HAND2 </it>in 20 primary NBs indicated concurrent expression levels of the two genes, which was confirmed by microarray analysis of 236 primary NBs (Pearson's correlation coefficient r = 0.65). While <it>DEIN </it>expression in the latter cohort was associated with stage 4S (p = 0.02), <it>HAND2 </it>expression was not associated with tumor stage. In contrast, both <it>HAND2 </it>and <it>DEIN </it>transcript levels were highly associated with age at diagnosis <12 months (p = 0.001). The intergenic region shows substantial homology in different species (89%, 72% and 53% identity between human and mouse, chicken and zebrafish, respectively) and contains many highly conserved putative transcription factor binding sites. Using luciferase reporter gene constructs, asymmetrical bidirectional promoter activity was found in four NB cell lines: In <it>DEIN </it>orientation, an average 3.4 fold increase in activity was observed as compared to the promoterless vector, whereas an average 15.4 fold activation was detected in <it>HAND2 </it>orientation. The presence of two highly conserved putative regulatory elements, one of which was shown to enhance <it>HAND2 </it>expression in branchial arches previously, displayed weak repressor activity for both genes.</p> <p>Conclusion</p> <p><it>HAND2 </it>and <it>DEIN </it>represent a gene pair that is tightly linked by a bidirectional promoter in an evolutionary highly conserved manner. Expression of both genes in NB is co-regulated by asymmetrical activity of this promoter and modulated by the activity of two cis-regulatory elements acting as weak repressors. The concurrent quantitative and tissue specific expression of <it>HAND2 </it>and <it>DEIN </it>suggests a functional link between both genes.</p

Cerebral neoplastic enhancing lesions: Multicenter, randomized, crossover intraindividual comparison between gadobutrol (1.0M) and gadoterate meglumine (0.5M) at 0.1mmolGd/kg body weight in a clinical setting

OBJECTIVE: Two macrocyclic extracellular contrast agents, one-molar neutral gadobutrol and ionic gadoterate meglumine, were compared to determine the overall preference for one or the other in a clinical setting. MATERIALS AND METHODS: Multicenter, randomized, single-blind, intra-individually controlled, comparison study with a corresponding blinded read. Efficacy analysis was based on 136 patients who underwent identical MRI examinations: group A first received 1.0M gadobutrol followed by 0.5M gadoterate meglumine 48 h to 7 days later; group B had a reversed administration order. Three independent blinded readers assessed off-site their overall diagnostic preference (primary efficacy parameter) based on a matched pairs approach. RESULTS: Superiority of gadobutrol over gadoterate meglumine was demonstrated for the qualitative assessment of overall preference across all readers by a statistically significant difference between both contrast agents for this primary endpoint. Preferences in lesion enhancement (secondary endpoint) were also found significantly in favor of gadobutrol. For preference in lesion delineation from surrounding tissue/edema and for internal structure only a trend towards a higher proportion for gadobutrol was found (except for internal structure reported by one reader, which showed a result of statistical significance). Lesion contrast and relative lesion enhancement (quantitative parameters) were statistically significantly higher for gadobutrol compared to gadoterate meglumine. CONCLUSION: Contrast-enhanced MRI of neoplastic brain lesions at a dose of 0.1 mmol Gd/kg body weight, assessed in a standardized off-site blinded reading, results in a significantly higher qualitative and quantitative preference for gadobutrol compared to gadoterate meglumine