In the core of a stroke, cell death occurs within minutes. In the penumbra, activity quickly drops, but cells typically remain viable for several hours. Improving neuronal survival in the penumbra is Show more
In the core of a stroke, cell death occurs within minutes. In the penumbra, activity quickly drops, but cells typically remain viable for several hours. Improving neuronal survival in the penumbra is crucial for enhancing recovery in patients with stroke. Earlier work showed that mild activation may improve recovery, but the mechanisms are unclear. Brain-derived neurotrophic factor (BDNF) is well recognized for its neuroprotective functions via activation of tyrosine receptor kinase B (TrkB) receptors, and its release is activity-dependent. This study explored the role of BDNF/TrkB signaling in neuronal survival under hypoxic conditions, using cultures of dissociated cortical rat neurons. When exposed to hypoxia, activity quickly drops and cells become apoptotic after ∼12 h, similar to observations in the ischemic penumbra. Inhibition of the TrkB receptor in healthy, normoxic cultures led to a fivefold increase in apoptosis, confirming the importance of BDNF/TrkB signaling for cell viability in these preparations. The addition of BDNF to hypoxic cultures significantly improved neuronal survival, comparable with the effects of mild activation. These findings suggest that the beneficial effect of mild stimulation to prevent apoptosis in hypoxic cultures is mediated by BDNF/TrkB signaling, offering insights for potential therapeutic strategies aimed at promoting neuronal recovery after a stroke. Show less
Small intestinal neuroendocrine tumors (SINET) are the commonest malignancy of the small intestine; however, underlying pathogenic mechanisms remain poorly characterized. Whole-genome and -exome seque Show more
Small intestinal neuroendocrine tumors (SINET) are the commonest malignancy of the small intestine; however, underlying pathogenic mechanisms remain poorly characterized. Whole-genome and -exome sequencing has demonstrated that SINETs are mutationally quiet, with the most frequent known mutation in the cyclin-dependent kinase inhibitor 1B gene (CDKN1B) occurring in only ∼8% of tumors, suggesting that alternative mechanisms may drive tumorigenesis. The aim of this study is to perform genome-wide molecular profiling of SINETs in order to identify pathogenic drivers based on molecular profiling. This study represents the largest unbiased integrated genomic, epigenomic, and transcriptomic analysis undertaken in this tumor type. Here, we present data from integrated molecular analysis of SINETs (n = 97), including whole-exome or targeted CDKN1B sequencing (n = 29), HumanMethylation450 BeadChip (Illumina) array profiling (n = 69), methylated DNA immunoprecipitation sequencing (n = 16), copy-number variance analysis (n = 47), and Whole-Genome DASL (Illumina) expression array profiling (n = 43). Based on molecular profiling, SINETs can be classified into three groups, which demonstrate significantly different progression-free survival after resection of primary tumor (not reached at 10 years vs. 56 months vs. 21 months, P = 0.04). Epimutations were found at a recurrence rate of up to 85%, and 21 epigenetically dysregulated genes were identified, including CDX1 (86%), CELSR3 (84%), FBP1 (84%), and GIPR (74%). This is the first comprehensive integrated molecular analysis of SINETs. We have demonstrated that these tumors are highly epigenetically dysregulated. Furthermore, we have identified novel molecular subtypes with significant impact on progression-free survival. Show less