Nuclear factor IA is expressed in astrocytomas and is associated with improved survival

Nuclear factor IA (NFIA) is a transcription factor that specifies glial cell identity and promotes astrocyte differentiation during embryonic development. Its expression and function in gliomas are not known. Here, we examined NFIA protein expression in gliomas and its association with clinical outcome in pediatric malignant astrocytomas. We analyzed expression of NFIA by immunohistochemistry in 88 existing glioma specimens from Childrens Hospital Los Angeles and the University of Southern California. Association between NFIA expression and progression-free survival (PFS) was examined in high-grade astrocytomas for which clinical data were available (n = 23, all children). NFIA was highly expressed in astrocytomas of all grades, but only in a minority of cells in oligodendroglial tumors. NFIA was expressed on a higher percentage of tumor cells in low-grade astrocytomas (91 ± 5% and 77 ± 14% in World Health Organization [WHO] I and II, respectively) compared with high-grade astrocytomas (48 ± 18% and 37 ± 16% in WHO III and IV, respectively; P < .001, low- vs high-grade astrocytomas). There was a significant association between NFIA expression and PFS in children with astrocytoma WHO grade III or IV (Cox regression P = .019; logrank trend test for NFIA tertiles P = .0040 and NFIA quartiles P = .014). The association was not consistently significant in this small series of patients after adjustment was made for WHO grade III or IV. This is the first study to demonstrate expression of NFIA protein in astrocytomas and its association with grades of astrocytoma and PFS, suggesting that NFIA may play a role in astrocytoma biology

The Chromatin-Modifying Protein HMGA2 Promotes Atypical Teratoid/Rhabdoid Cell Tumorigenicity

Atypical teratoid/rhabdoid tumor (AT/RT) is an aggressive pediatric central nervous system tumor. The poor prognosis of AT/RT warrants identification of novel therapeutic targets and strategies. High mobility group A2 (HMGA2) is a developmentally important chromatin modifying protein that positively regulates tumor growth, self-renewal and invasion in other cancer types. HMGA2 was recently identified as being upregulated in AT/RT tissue, but the role of HMGA2 in brain tumors remains unknown. We used lentiviral short hairpin RNA to suppress HMGA2 in AT/RT cell lines and found that loss of HMGA2 led to decreased cell growth, proliferation, colony formation and increased apoptosis. We also found that suppression of HMGA2 negatively affected in vivo orthotopic xenograft tumor growth, more than doubling median survival of the mice from 58 days to 153 days. Our results indicate a role for HMGA2 in AT/RT in vitro and in vivo and demonstrate that HMGA2 is a potential therapeutic target in these lethal pediatric tumors

Maximizing the potential of aggressive mouse tumor models in preclinical drug testing.

Atypical teratoid rhabdoid tumor (ATRT) is an aggressive embryonal brain tumor among infants and young children. Two challenges exist for preclinical testing in ATRT. First, genetically quiet, ATRT is a difficult tumor to target molecularly. Tumor cells need to divide to propagate tumor growth-intercepting the common crossroads in cell cycle progression is a feasible strategy. KIF11 is needed for bipolar spindle formation in metaphase. We identified KIF11 as a universal target of all ATRT-molecular-subtypes. Ispinesib, a KIF11-inhibitor, effectively inhibited tumor proliferation in all seven cell lines. A second challenge-a major challenge in preclinical drug testing in-vivo among aggressive tumor models, is the narrow therapeutic window to administer drugs within the limited murine lifespan. Our most aggressive ATRT tumor model was lethal in all mice within ~ 1 month of tumor implantation. Such short-surviving mouse models are difficult to employ for preclinical drug testing due to the narrow time window to administer drugs. To overcome this time restriction, we developed a clinical staging system which allowed physically-fit mice to continue treatment, in contrast to the conventional method of fixed drug-dose-duration regimen in preclinical testing which will not be feasible in such short-surviving mouse models. We validated this approach in a second embryonal brain tumor, medulloblastoma. This is a clinically relevant, cost-efficient approach in preclinical testing for cancer and non-cancer disease phenotypes. Widely used preclinical mouse models are not the most accurate and lack the aggressive tumor spectrum found within a single tumor type. Mice bearing the most aggressive tumor spectrum progress rapidly in the limited murine life-span, resulting in a narrow therapeutic window to administer drugs, and are thus difficult to employ in preclinical testing. Our approach overcomes this challenge. We discovered ispinesib is efficacious against two embryonal brain tumor types

SMARCB1 loss induces druggable cyclin D1 deficiency via upregulation of MIR17HG in atypical teratoid rhabdoid tumors

Atypical teratoid rhabdoid tumor (ATRT) is a fatal pediatric malignancy of the central neural system lacking effective treatment options. It belongs to the rhabdoid tumor family and is usually caused by biallelic inactivation of SMARCB1, encoding a key subunit of SWI/SNF chromatin remodeling complexes. Previous studies proposed that SMARCB1 loss drives rhabdoid tumor by promoting cell cycle through activating transcription of cyclin D1 while suppressing p16. However, low cyclin D1 protein expression is observed in most ATRT patient tumors. The underlying mechanism and therapeutic implication of this molecular trait remain unknown. Here, we show that SMARCB1 loss in ATRT leads to the reduction of cyclin D1 expression by upregulating MIR17HG, a microRNA (miRNA) cluster known to generate multiple miRNAs targeting CCND1. Furthermore, we find that this cyclin D1 deficiency in ATRT results in marked in vitro and in vivo sensitivity to the CDK4/6 inhibitor palbociclib as a single agent. Our study identifies a novel genetic interaction between SMARCB1 and MIR17HG in regulating cyclin D1 in ATRT and suggests a rationale to treat ATRT patients with FDA- approved CDK4/6 inhibitors. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156416/2/path5493.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156416/1/path5493_am.pd

Disrupting LIN28 in atypical teratoid rhabdoid tumors reveals the importance of the mitogen activated protein kinase pathway as a therapeutic target

Atypical teratoid rhabdoid tumor (AT/RT) is among the most fatal of all pediatric brain tumors. Aside from loss of function mutations in the SMARCB1 (BAF47/INI1/SNF5) chromatin remodeling gene, little is known of other molecular drivers of AT/RT. LIN28A and LIN28B are stem cell factors that regulate thousands of RNAs and are expressed in aggressive cancers. We identified high-levels of LIN28A and LIN28B in AT/RT primary tumors and cell lines, with corresponding low levels of the LIN28-regulated microRNAs of the let-7 family. Knockdown of LIN28A by lentiviral shRNA in the AT/RT cell lines CHLA-06-ATRT and BT37 inhibited growth, cell proliferation and colony formation and induced apoptosis. Suppression of LIN28A in orthotopic xenograft models led to a more than doubling of median survival compared to empty vector controls (48 vs 115 days). LIN28A knockdown led to increased expression of let-7b and let-7g microRNAs and a down-regulation of KRAS mRNA. AT/RT primary tumors expressed increased mitogen activated protein (MAP) kinase pathway activity, and the MEK inhibitor selumetinib (AZD6244) decreased AT/RT growth and increased apoptosis. These data implicate LIN28/RAS/MAP kinase as key drivers of AT/RT tumorigenesis and indicate that targeting this pathway may be a therapeutic option in this aggressive pediatric malignancy

Microdeletion del(22)(q12.2) encompassing the facial development-associated gene, MN1 (meningioma 1) in a child with Pierre-Robin sequence (including cleft palate) and neurofibromatosis 2 (NF2): a case report and review of the literature

<p>Abstract</p> <p>Background</p> <p>Pierre-Robin sequence (PRS) is defined by micro- and/or retrognathia, glossoptosis and cleft soft palate, either caused by deformational defect or part of a malformation syndrome. Neurofibromatosis type 2 (NF2) is an autosomal dominant syndrome caused by mutations in the <it>NF2 </it>gene on chromosome 22q12.2. NF2 is characterized by bilateral vestibular schwannomas, spinal cord schwannomas, meningiomas and ependymomas, and juvenile cataracts. To date, NF2 and PRS have not been described together in the same patient.</p> <p>Case presentation</p> <p>We report a female with PRS (micrognathia, cleft palate), microcephaly, ocular hypertelorism, mental retardation and bilateral hearing loss, who at age 15 was also diagnosed with severe NF2 (bilateral cerebellopontine schwannomas and multiple extramedullary/intradural spine tumors). This is the first published report of an individual with both diagnosed PRS and NF2. High resolution karyotype revealed 46, XX, del(22)(q12.1q12.3), FISH confirmed a deletion encompassing <it>NF2</it>, and chromosomal microarray identified a 3,693 kb deletion encompassing multiple genes including <it>NF2 </it>and <it>MN1 </it>(meningioma 1).</p> <p>Five additional patients with craniofacial dysmorphism and deletion in chromosome 22-adjacent-to or containing <it>NF2 </it>were identified in PubMed and the DECIPHER clinical chromosomal database. Their shared chromosomal deletion encompassed <it>MN1</it>, <it>PITPNB </it>and <it>TTC28</it>. <it>MN1</it>, initially cloned from a patient with meningioma, is an oncogene in murine hematopoiesis and participates as a fusion gene (<it>TEL</it>/<it>MN1</it>) in human myeloid leukemias. Interestingly, <it>Mn1</it>-haploinsufficient mice have abnormal skull development and secondary cleft palate. Additionally, <it>Mn1 </it>regulates maturation and function of calvarial osteoblasts and is an upstream regulator of <it>Tbx22</it>, a gene associated with murine and human cleft palate. This suggests that deletion of <it>MN1 </it>in the six patients we describe may be causally linked to their cleft palates and/or craniofacial abnormalities.</p> <p>Conclusions</p> <p>Thus, our report describes a <it>NF2</it>-adjacent chromosome 22q12.2 deletion syndrome and is the first to report association of <it>MN1 </it>deletion with abnormal craniofacial development and/or cleft palate in humans.</p

Induction of Membrane Ceramides: A Novel Strategy to Interfere with T Lymphocyte Cytoskeletal Reorganisation in Viral Immunosuppression

Silencing of T cell activation and function is a highly efficient strategy of immunosuppression induced by pathogens. By promoting formation of membrane microdomains essential for clustering of receptors and signalling platforms in the plasma membrane, ceramides accumulating as a result of membrane sphingomyelin breakdown are not only essential for assembly of signalling complexes and pathogen entry, but also act as signalling modulators, e. g. by regulating relay of phosphatidyl-inositol-3-kinase (PI3K) signalling. Their role in T lymphocyte functions has not been addressed as yet. We now show that measles virus (MV), which interacts with the surface of T cells and thereby efficiently interferes with stimulated dynamic reorganisation of their actin cytoskeleton, causes ceramide accumulation in human T cells in a neutral (NSM) and acid (ASM) sphingomyelinase–dependent manner. Ceramides induced by MV, but also bacterial sphingomyelinase, efficiently interfered with formation of membrane protrusions and T cell spreading and front/rear polarisation in response to β1 integrin ligation or αCD3/CD28 activation, and this was rescued upon pharmacological or genetic ablation of ASM/NSM activity. Moreover, membrane ceramide accumulation downmodulated chemokine-induced T cell motility on fibronectin. Altogether, these findings highlight an as yet unrecognised concept of pathogens able to cause membrane ceramide accumulation to target essential processes in T cell activation and function by preventing stimulated actin cytoskeletal dynamics