Intestinal gangrene secondary to congenital transmesenteric hernia in a child misdiagnosed with gastrointestinal bleeding: A case report.

BACKGROUND: Congenital transmesenteric hernia in children is a rare and potentially fatal form of internal abdominal hernia, and no specific clinical symptoms can be observed preoperatively. Therefore, this condition is not widely known among clinicians, and it is easily misdiagnosed, resulting in disastrous effects. CASE SUMMARY: This report presents the case of a 13-year-old boy with a chief complaint of abdominal pain and vomiting and a history of duodenal ulcer. The patient was misdiagnosed with gastrointestinal bleeding and treated conservatively at first. Then, the patient's symptoms were aggravated and he presented in a shock-like state. Computed tomography revealed a suspected internal hernia, extensive small intestinal obstruction, and massive effusion in the abdominal and pelvic cavity. Intraoperative exploration found a small mesenteric defect approximately 3.5 cm in diameter near the ileocecal valve, and there was about 1.8 m of herniated small intestine that was treated by resection and anastomosis. The patient recovered well and was followed for more than 5 years without developing short bowel syndrome. CONCLUSION: In this report, we review the pathogenesis, presentation, diagnosis, and treatment of congenital transmesenteric hernia in children.

RP58 Represses Transcriptional Programs Linked to Nonneuronal Cell Identity and Glioblastoma Subtypes in Developing Neurons.

How mammalian neuronal identity is progressively acquired and reinforced during development is not understood. We have previously shown that loss of RP58 (ZNF238 or ZBTB18), a BTB/POZ-zinc finger-containing transcription factor, in the mouse brain leads to microcephaly, corpus callosum agenesis, and cerebellum hypoplasia and that it is required for normal neuronal differentiation. The transcriptional programs regulated by RP58 during this process are not known. Here, we report for the first time that in embryonic mouse neocortical neurons a complex set of genes normally expressed in other cell types, such as those from mesoderm derivatives, must be actively repressed in vivo and that RP58 is a critical regulator of these repressed transcriptional programs. Importantly, gene set enrichment analysis (GSEA) analyses of these transcriptional programs indicate that repressed genes include distinct sets of genes significantly associated with glioma progression and/or pluripotency. We also demonstrate that reintroducing RP58 in glioma stem cells leads not only to aspects of neuronal differentiation but also to loss of stem cell characteristics, including loss of stem cell markers and decrease in stem cell self-renewal capacities. Thus, RP58 acts as an in vivo master guardian of the neuronal identity transcriptome, and its function may be required to prevent brain disease development, including glioma progression.

Transcriptome signatures associated with meningioma progression.

Meningiomas are the most common primary brain tumor of adults. The majority are benign (WHO grade I), with a mostly indolent course; 20% of them (WHO grade II and III) are, however, considered aggressive and require a more complex management. WHO grade II and III tumors are heterogeneous and, in some cases, can develop from a prior lower grade meningioma, although most arise de novo. Mechanisms leading to progression or implicated in de novo grade II and III tumorigenesis are poorly understood. RNA-seq was used to profile the transcriptome of grade I, II, and III meningiomas and to identify genes that may be involved in progression. Bioinformatic analyses showed that grade I meningiomas that progress to a higher grade are molecularly different from those that do not. As such, we identify GREM2, a regulator of the BMP pathway, and the snoRNAs SNORA46 and SNORA48, as being significantly reduced in meningioma progression. Additionally, our study has identified several novel fusion transcripts that are differentially present in meningiomas, with grade I tumors that did not progress presenting more fusion transcripts than all other tumors. Interestingly, our study also points to a difference in the tumor immune microenvironment that correlates with histopathological grade.

Combination PD-1 blockade and irradiation of brain metastasis induces an effective abscopal effect in melanoma.

Nearly half of melanoma patients develop brain metastases during the course of their disease. Despite advances in both localized radiation and systemic immunotherapy, brain metastases remain difficult to treat, with most patients surviving less than 5 months from the time of diagnosis. While both treatment regimens have individually shown considerable promise in treating metastatic melanoma, there is interest in combining these strategies to take advantage of potential synergy. In order to study the ability of local radiation and anti-PD-1 immunotherapy to induce beneficial anti-tumor immune responses against distant, unirradiated tumors, we used two mouse models of metastatic melanoma in the brain, representing BRAF mutant and non-mutant tumors. Combination treatments produced a stronger systemic anti-tumor immune response than either treatment alone. This resulted in reduced tumor growth and larger numbers of activated, cytotoxic CD8+ T cells, even in the unirradiated tumor, indicative of an abscopal effect. The immune-mediated effects were present regardless of BRAF status. These data suggest that irradiation of brain metastases and anti-PD-1 immunotherapy together can induce abscopal anti-tumor responses that control both local and distant disease.

Hypoxic Induction of Vasorin Regulates Notch1 Turnover to Maintain Glioma Stem-like Cells.

Tumor hypoxia is associated with poor patient survival and is a characteristic of glioblastoma. Notch signaling is implicated in maintaining glioma stem-like cells (GSCs) within the hypoxic niche, although the molecular mechanisms linking hypoxia to Notch activation have not been clearly delineated. Here we show that Vasorin is a critical link between hypoxia and Notch signaling in GSCs. Vasorin is preferentially induced in GSCs by a HIF1α/STAT3 co-activator complex and stabilizes Notch1 protein at the cell membrane. This interaction prevents Numb from binding Notch1, rescuing it from Numb-mediated lysosomal degradation. Thus, Vasorin acts as a switch to augment Notch signaling under hypoxic conditions. Vasorin promotes tumor growth and reduces survival in mouse models of glioblastoma, and its expression correlates with increased aggression of human gliomas. These findings provide mechanistic insights into how hypoxia promotes Notch signaling in glioma and identify Vasorin as a potential therapeutic target.

Rapid Chromatin Switch in the Direct Reprogramming of Fibroblasts to Neurons.

How transcription factors (TFs) reprogram one cell lineage to another remains unclear. Here, we define chromatin accessibility changes induced by the proneural TF Ascl1 throughout conversion of fibroblasts into induced neuronal (iN) cells. Thousands of genomic loci are affected as early as 12 hr after Ascl1 induction. Surprisingly, over 80% of the accessibility changes occur between days 2 and 5 of the 3-week reprogramming process. This chromatin switch coincides with robust activation of endogenous neuronal TFs and nucleosome phasing of neuronal promoters and enhancers. Subsequent morphological and functional maturation of iN cells is accomplished with relatively little chromatin reconfiguration. By integrating chromatin accessibility and transcriptome changes, we built a network model of dynamic TF regulation during iN cell reprogramming and identified Zfp238, Sox8, and Dlx3 as key TFs downstream of Ascl1. These results reveal a singular, coordinated epigenomic switch during direct reprogramming, in contrast to stepwise cell fate transitions in development.

Ablation of BRaf impairs neuronal differentiation in the postnatal hippocampus and cerebellum.

This study focuses on the role of the kinase BRaf in postnatal brain development. Mice expressing truncated, non-functional BRaf in neural stem cell-derived brain tissue demonstrate alterations in the cerebellum, with decreased sizes and fuzzy borders of the glomeruli in the granule cell layer. In addition we observed reduced numbers and misplaced ectopic Purkinje cells that showed an altered structure of their dendritic arborizations in the hippocampus, while the overall cornus ammonis architecture appeared to be unchanged. In male mice lacking BRaf in the hippocampus the size of the granule cell layer was normal at postnatal day 12 (P12) but diminished at P21, as compared to control littermates. This defect was caused by a reduced ability of dentate gyrus progenitor cells to differentiate into NeuN positive granule cell neurons. In vitro cell culture of P0/P1 hippocampal cells revealed that BRaf deficient cells were impaired in their ability to form microtubule-associated protein 2 positive neurons. Together with the alterations in behaviour, such as autoaggression and loss of balance fitness, these observations indicate that in the absence of BRaf all neuronal cellular structures develop, but neuronal circuits in the cerebellum and hippocampus are partially disturbed besides impaired neuronal generation in both structures.

Formation of telomeric repeat-containing RNA (TERRA) foci in highly proliferating mouse cerebellar neuronal progenitors and medulloblastoma.

Telomeres play crucial roles in the maintenance of genome integrity and control of cellular senescence. Most eukaryotic telomeres can be transcribed to generate a telomeric repeat-containing RNA (TERRA) that persists as a heterogeneous nuclear RNA and can be developmentally regulated. However, the precise function and regulation of TERRA in normal and cancer cell development remains poorly understood. Here, we show that TERRA accumulates in highly proliferating normal and cancer cells, and forms large nuclear foci, which are distinct from previously characterized markers of DNA damage or replication stress. Using a mouse model for medulloblastoma driven by chronic Sonic hedgehog (SHH) signaling, TERRA RNA was detected in tumor, but not adjacent normal cells using both RNA fluorescence in situ hybridization (FISH) and northern blotting. RNA FISH revealed the formation of TERRA foci (TERFs) in the nuclear regions of rapidly proliferating tumor cells. In the normal developing cerebellum, TERRA aggregates could also be detected in highly proliferating zones of progenitor neurons. SHH could enhance TERRA expression in purified granule progenitor cells in vitro, suggesting that proliferation signals contribute to TERRA expression in responsive tissue. TERRA foci did not colocalize with γH2AX foci, promyelocytic leukemia (PML) or Cajal bodies in mouse tumor tissue. We also provide evidence that TERRA is elevated in a variety of human cancers. These findings suggest that elevated TERRA levels reflect a novel early form of telomere regulation during replication stress and cancer cell evolution, and the TERRA RNA aggregates may form a novel nuclear body in highly proliferating mammalian cells.

Rp58 is essential for the growth and patterning of the cerebellum and for glutamatergic and GABAergic neuron development.

Cerebellum development depends on the correct differentiation of progenitors into neurons, a process controlled by a transcriptional program that remains poorly understood. Here we show that neural-specific deletion of the BTB/POZ zinc-finger transcription factor-encoding gene Rp58 (Znf238, Zfp238) causes severe cerebellar hypoplasia and developmental failure of Purkinje neurons, Bergmann glia and granule neurons. Deletion of Rp58 in mouse embryonic Atoh1(+) progenitors leads to strong defects in growth and foliation owing to its crucial role in the differentiation of granule neurons. Analysis of the Rp58 mutant at E14.5 demonstrates that Rp58 is required for the development of both glutamatergic and GABAergic neurons. Rp58 mutants show decreased proliferation of glutamatergic progenitors at E14.5. In addition, Rp58 ablation results in a reduced number of GABAergic Pax2(+) neurons at E16.5 together with defects in the transcriptional program of ventricular zone progenitors. Our results indicate that Rp58 is essential for the growth and organization of the cerebellum and regulates the development of both GABAergic and glutamatergic neurons.

Design, synthesis, and biological evaluation of estrone-derived hedgehog signaling inhibitors.

The design, synthesis and biological evaluation of new analogs of the naturally occurring compound cyclopamine, a Hedgehog signaling inhibitor, are described. Stucture-activity relationship studies lead to an evolving model for the pharmacophore of this medically promising compound class of anti-cancer chemotherapeutic agents.

Studies directed toward the elucidation of the pharmacophore of steroid-based Sonic Hedgehog signaling inhibitors.

Previous work from our laboratory has established that the readily available steroid-based analog 2 of cyclopamine 1 is, like 1, a highly potent inhibitor of Hedgehog signaling. The first structure-activity relationship studies on 2, i.e., the synthesis and biological evaluation of both the C-17 epi analog 4 and the C-3 deoxy analog 11, both of which are more potent than cyclopamine 1, are described. The implications of these results for the emerging pharmacophore of these Sonic Hedgehog signaling inhibitors are discussed.

Stereoselective synthesis of F-ring saturated estrone-derived inhibitors of Hedgehog signaling based on cyclopamine.

Previous work in this laboratory established that the readily available F-ring aromatic analog of cyclopamine is a highly potent inhibitor of Hedgehog signaling. The synthesis and biological evaluation of two F-ring saturated analogs that are more potent than the F-ring aromatic structure are reported.

ZNF238 is expressed in postmitotic brain cells and inhibits brain tumor growth.

Brain tumors such as medulloblastoma (MB) and glioblastoma multiforme (GBM) can derive from neural precursors. For instance, many MBs are thought to arise from the uncontrolled proliferation of cerebellar granule neuron precursors (GNP). GNPs normally proliferate in early postnatal stages in mice but then they become postmitotic and differentiate into granule neurons. The proliferation of neural precursors, GNPs, as well as at least subsets of GBM and MB depends on Hedgehog signaling. However, the gene functions that are lost or suppressed in brain tumors and that normally promote the proliferation arrest and differentiation of precursors remain unclear. Here we have identified a member of the BTB-POZ and zinc finger family, ZNF238, as a factor highly expressed in postmitotic GNPs and differentiated neurons. In contrast, proliferating GNPs as well as MB and GBM express low or no ZNF238. Functionally, inhibition of ZNF238 expression in mouse GNPs decreases the expression of the neuronal differentiation markers MAP2 and NeuN and downregulates the expression of the cell cycle arrest protein p27, a regulator of GNP differentiation. Conversely, reinstating ZNF238 expression in MB and GBM cells drastically decreases their proliferation and promotes cell death. It also downregulates cyclin D1 while increasing MAP2 and p27 protein levels. Importantly, ZNF238 antagonizes MB and GBM tumor growth in vivo in xenografts. We propose that the antiproliferative functions of ZNF238 in normal GNPs and possibly other neural precursors counteract brain tumor formation. ZNF238 is thus a novel brain tumor suppressor and its reactivation in tumors could open a novel anticancer strategy.

Cortical migration defects in mice expressing A-RAF from the B-RAF locus.

We have previously shown that mice lacking the protein kinase B-RAF have defects in both neural and endothelial cell lineages and die around embryonic day 12 (E12). To delineate the function of B-RAF in the brain, B-RAF KIN/KIN mice lacking B-RAF and expressing A-RAF under the control of the B-RAF locus were created. B-RAF KIN/KIN embryos displayed no vascular defects, no endothelial and neuronal apoptosis, or gross developmental abnormalities, and a significant proportion of these animals survived for up to 8 weeks. Cell proliferation in the neocortex was reduced from E14.5 onwards. Newborn cortical neurons were impaired in their migration toward the cortical plate, causing a depletion of Brn-2-expressing pyramidal neurons in layers II, III, and V of the postnatal cortex. Our data reveal that B-RAF is an important mediator of neuronal survival, migration, and dendrite formation and that A-RAF cannot fully compensate for these functions.