Browsing by Subject "NF1"

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    Aberrant Neural Activity in Cortico-Striatal-Limbic Circuitry Underlies Behavioral Deficits in a Mouse Model of Neurofibromatosis Type 1
    (2022-05) Drozd, Hayley Paulina; McKinzie, David L.; Clapp, D. Wade; Shekhar, Anantha; Lukkes, Jodi L.; Lapish, Christopher L.; Block, Michelle L.
    Nearly 18% of children are diagnosed with developmental disabilities. Autism spectrum disorders (ASDs) and attention deficit hyperactivity disorder (ADHD) are increasingly common developmental disabilities, but neither is well understood. ADHD and ASD are both prevalent in the genetic disorder Neurofibromatosis type 1 (NF1) which impairs the Ras-MAPK/ERK pathway through mutation of the neurofibromin gene (NF1+/−). More broadly, syndromic forms of developmental disorders are often caused by mutations of proteins in pathways interconnected with Ras including TSC1/2, FMR1, and SynGAP. Of NF1 patients, around 30-50% are diagnosed with ASDs and more than 60% with ADHD. These studies are the first to show that male mice haploinsufficient for the Nf1 gene (Nf1+/−) exhibit deficits in behavioral inhibition in multiple contexts, a key feature of ADHD. They exhibit hyperactivity and impulsivity in an open field, delay discounting task, and cliff avoidance reaction test, rescuable through treatment with the clinically effective ADHD drug, guanfacine (α2A adrenergic receptor agonist). Previous experiments in our lab identified social deficits including deficits in consolidation of social memory. Using optogenetics and awake behaving electrode recordings, we explored the role of the cortico-striatal-limbic circuitry in impulsivity and in social deficits in male Nf1+/− mice. Manipulation of the prefrontal cortex, nucleus accumbens, or basolateral amygdala through optogenetics rescued social deficits. These studies are the first to record brain activity in a preclinical model of NF1 during impulsive behavior, finding broad spectrum changes across slow, delta, theta, and gamma oscillatory frequencies and decreased synchrony of the prefrontal cortex and nucleus accumbens during a delay discounting task. Overall, Nf1+/− male mice with deletion of a single NF1 gene recapitulate cognitive phenotypes of NF1 patients and are a useful model system to identify alterations in neural circuitry associated with ASD and ADHD.
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    A Collaborative Model for Accelerating the Discovery and Translation of Cancer Therapies
    (American Association for Cancer Research, 2017-11-01) Maertens, Ophélia; McCurrach, Mila E.; Braun, Benjamin S.; De Raedt, Thomas; Epstein, Inbal; Huang, Tannie Q.; Lauchle, Jennifer O.; Lee, Hyerim; Wu, Jianqiang; Cripe, Timothy P.; Clapp, D. Wade; Ratner, Nancy; Shannon, Kevin; Cichowski, Karen; Pediatrics, School of Medicine
    Preclinical studies using genetically engineered mouse models (GEMM) have the potential to expedite the development of effective new therapies; however, they are not routinely integrated into drug development pipelines. GEMMs may be particularly valuable for investigating treatments for less common cancers, which frequently lack alternative faithful models. Here, we describe a multicenter cooperative group that has successfully leveraged the expertise and resources from philanthropic foundations, academia, and industry to advance therapeutic discovery and translation using GEMMs as a preclinical platform. This effort, known as the Neurofibromatosis Preclinical Consortium (NFPC), was established to accelerate new treatments for tumors associated with neurofibromatosis type 1 (NF1). At its inception, there were no effective treatments for NF1 and few promising approaches on the horizon. Since 2008, participating laboratories have conducted 95 preclinical trials of 38 drugs or combinations through collaborations with 18 pharmaceutical companies. Importantly, these studies have identified 13 therapeutic targets, which have inspired 16 clinical trials. This review outlines the opportunities and challenges of building this type of consortium and highlights how it can accelerate clinical translation. We believe that this strategy of foundation-academic-industry partnering is generally applicable to many diseases and has the potential to markedly improve the success of therapeutic development.
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    Correction: Expanding the clinical phenotype of individuals with a 3-bp in-frame deletion of the NF1 gene (c.2970_2972del): an update of genotype–phenotype correlation
    (Elsevier, 2019-03) Koczkowska, Magdalena; Callens, Tom; Gomes, Alicia; Sharp, Angela; Chen, Yunjia; Hicks, Alesha D.; Aylsworth, Arthur S.; Azizi, Amedeo A.; Basel, Donald G.; Bellus, Gary; Bird, Lynne M.; Blazo, Maria A.; Burke, Leah W.; Cannon, Ashley; Collins, Felicity; DeFilippo, Colette; Denayer, Ellen; Digilio, Maria C.; Dills, Shelley K.; Dosa, Laura; Greenwood, Robert S.; Griffis, Cristin; Gupta, Punita; Hachen, Rachel K.; Hernández-Chico, Concepción; Janssens, Sandra; Jones, Kristi J.; Jordan, Justin T.; Kannu, Peter; Korf, Bruce R.; Lewis, Andrea M.; Listernick, Robert H.; Lonardo, Fortunato; Mahoney, Maurice J.; Ojeda, Mayra Martinez; McDonald, Marie T.; McDougall, Carey; Mendelsohn, Nancy; Miller, David T.; Mori, Mari; Oostenbrink, Rianne; Perreault, Sebastién; Pierpont, Mary Ella; Piscopo, Carmelo; Pond, Dinel A.; Randolph, Linda M.; Rauen, Katherine A.; Rednam, Surya; Rutledge, S. Lane; Saletti, Veronica; Schaefer, G. Bradley; Schorry, Elizabeth K.; Scott, Daryl A.; Shugar, Andrea; Siqveland, Elizabeth; Starr, Lois J.; Syed, Ashraf; Trapane, Pamela L.; Ullrich, Nicole J.; Wakefield, Emily G.; Walsh, Laurence E.; Wangler, Michael F.; Zackai, Elaine; Claes, Kathleen B.M.; Wimmer, Katharina; van Minkelen, Rick; De Luca, Alessandro; Martin, Yolanda; Legius, Eric; Messiaen, Ludwine M.; Neurology, School of Medicine
    Purpose: Neurofibromatosis type 1 (NF1) is characterized by a highly variable clinical presentation, but almost all NF1-affected adults present with cutaneous and/or subcutaneous neurofibromas. Exceptions are individuals heterozygous for the NF1 in-frame deletion, c.2970_2972del (p.Met992del), associated with a mild phenotype without any externally visible tumors. Methods: A total of 135 individuals from 103 unrelated families, all carrying the constitutional NF1 p.Met992del pathogenic variant and clinically assessed using the same standardized phenotypic checklist form, were included in this study. Results: None of the individuals had externally visible plexiform or histopathologically confirmed cutaneous or subcutaneous neurofi- bromas. We did not identify any complications, such as sympto-matic optic pathway gliomas (OPGs) or symptomatic spinal neurofibromas; however, 4.8% of individuals had nonoptic brain tumors, mostly low-grade and asymptomatic, and 38.8% had cognitive impairment/learning disabilities. In an individual with the NF1 constitutional c.2970_2972del and three astrocytomas, we provided proof that all were NF1-associated tumors given loss of heterozygosity at three intragenic NF1 microsatellite markers and c.2970_2972del. Conclusion: We demonstrate that individuals with the NF1 p.Met992del pathogenic variant have a mild NF1 phenotype lacking clinically suspected plexiform, cutaneous, or subcutaneous neurofi-bromas. However, learning difficulties are clearly part of the phenotypic presentation in these individuals and will require specialized care.
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    Early administration of imatinib mesylate reduces plexiform neurofibroma tumor burden with durable results after drug discontinuation in a mouse model of neurofibromatosis type 1
    (Wiley, 2020-05-27) Armstrong, Amy E.; Rhodes, Steven D.; Smith, Abbi; Chen, Shi; Bessler, Waylan; Ferguson, Michael J.; Jiang, Li; Li, Xiaohong; Yuan, Jin; Yang, Xianlin; Yang, Feng-Chun; Robertson, Kent A.; Ingram, David A.; Blakeley, Jaishri O.; Clapp, D. Wade; Pediatrics, School of Medicine
    BACKGROUND Neurofibromatosis type 1 (NF1) is a common genetic disorder characterized by plexiform neurofibromas (pNF), which are thought to be congenital tumors that arise in utero and enlarge throughout life. Genetic studies in murine models delineated an indispensable role for the stem cell factor (SCF)/c-kit pathway in pNF initiation and progression. A subsequent phase 2 clinical trial using imatinib mesylate to inhibit SCF/c-kit demonstrated tumor shrinkage in a subset of pre-existing pNF, however imatinib’s role on preventing pNF development has yet to be explored. PROCEDURE We evaluated the effect of imatinib dosed at 10–100 mg/kg/day for 12 weeks to 1-month old Nf1flox/flox;PostnCre(+) mice, prior to onset of pNF formation. To determine durability of response, we then monitored for pNF growth at later time points, comparing imatinib to vehicle treated mice. We assessed gross and histopathological analysis of tumor burden. RESULTS Imatinib administered preventatively led to a significant decrease in pNF number, even at doses as low as 10 mg/kg/day. Tumor development continued to be significantly inhibited after cessation of imatinib dosed at 50 and 100 mg/kg/day. In the cohort of treated mice that underwent prolonged follow-up, the size of residual tumors was significantly reduced as compared to age-matched littermates that received vehicle control. CONCLUSIONS Early administration of imatinib inhibits pNF genesis in vivo and effects are sustained after discontinuation of therapy. These findings may guide clinical use of imatinib in young NF1 patients prior to substantial development of pNF.
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    Expanding the clinical phenotype of individuals with a 3-bp in-frame deletion of the NF1 gene (c.2970_2972del): an update of genotype-phenotype correlation
    (Springer Nature, 2019-04) Koczkowska, Magdalena; Callens, Tom; Gomes, Alicia; Sharp, Angela; Chen, Yunjia; Hicks, Alesha D.; Aylsworth, Arthur S.; Azizi, Amedeo A.; Basel, Donald G.; Bellus, Gary; Bird, Lynne M.; Blazo, Maria A.; Burke, Leah W.; Cannon, Ashley; Collins, Felicity; DeFilippo, Colette; Denayer, Ellen; Digilio, Maria C.; Dills, Shelley K.; Dosa, Laura; Greenwood, Robert S.; Griffis, Cristin; Gupta, Punita; Hachen, Rachel K.; Hernández-Chico, Concepción; Janssens, Sandra; Jones, Kristi J.; Jordan, Justin T.; Kannu, Peter; Korf, Bruce R.; Lewis, Andrea M.; Listernick, Robert H.; Lonardo, Fortunato; Mahoney, Maurice J.; Ojeda, Mayra Martinez; McDonald, Marie T.; McDougall, Carey; Mendelsohn, Nancy; Miller, David T.; Mori, Mari; Oostenbrink, Rianne; Perreault, Sebastién; Pierpont, Mary Ella; Piscopo, Carmelo; Pond, Dinel A.; Randolph, Linda M.; Rauen, Katherine A.; Rednam, Surya; Rutledge, S. Lane; Saletti, Veronica; Schaefer, G. Bradley; Schorry, Elizabeth K.; Scott, Daryl A.; Shugar, Andrea; Siqveland, Elizabeth; Starr, Lois J.; Syed, Ashraf; Trapane, Pamela L.; Ullrich, Nicole J.; Wakefield, Emily G.; Walsh, Laurence E.; Wangler, Michael F.; Zackai, Elaine; Claes, Kathleen B. M.; Wimmer, Katharina; van Minkelen, Rick; De Luca, Alessandro; Martin, Yolanda; Legius, Eric; Messiaen, Ludwine M.; Neurology, School of Medicine
    PURPOSE: Neurofibromatosis type 1 (NF1) is characterized by a highly variable clinical presentation, but almost all NF1-affected adults present with cutaneous and/or subcutaneous neurofibromas. Exceptions are individuals heterozygous for the NF1 in-frame deletion, c.2970_2972del (p.Met992del), associated with a mild phenotype without any externally visible tumors. METHODS: A total of 135 individuals from 103 unrelated families, all carrying the constitutional NF1 p.Met992del pathogenic variant and clinically assessed using the same standardized phenotypic checklist form, were included in this study. RESULTS: None of the individuals had externally visible plexiform or histopathologically confirmed cutaneous or subcutaneous neurofibromas. We did not identify any complications, such as symptomatic optic pathway gliomas (OPGs) or symptomatic spinal neurofibromas; however, 4.8% of individuals had nonoptic brain tumors, mostly low-grade and asymptomatic, and 38.8% had cognitive impairment/learning disabilities. In an individual with the NF1 constitutional c.2970_2972del and three astrocytomas, we provided proof that all were NF1-associated tumors given loss of heterozygosity at three intragenic NF1 microsatellite markers and c.2970_2972del. CONCLUSION: We demonstrate that individuals with the NF1 p.Met992del pathogenic variant have a mild NF1 phenotype lacking clinically suspected plexiform, cutaneous, or subcutaneous neurofibromas. However, learning difficulties are clearly part of the phenotypic presentation in these individuals and will require specialized care.
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    Feasibility of using NF1-GRD and AAV for gene replacement therapy in NF1-associated tumors
    (Springer Nature, 2019-06) Bai, Ren-Yuan; Esposito, Dominic; Tam, Ada J.; McCormick, Frank; Riggins, Gregory J.; Clapp, D. Wade; Staedtke, Verena; Pediatrics, School of Medicine
    Neurofibromatosis type 1, including the highly aggressive malignant peripheral nerve sheath tumors (MPNSTs), is featured by the loss of functional neurofibromin 1 (NF1) protein resulting from genetic alterations. A major function of NF1 is suppressing Ras activities, which is conveyed by an intrinsic GTPase-activating protein-related domain (GRD). In this study, we explored the feasibility of restoring Ras GTPase via exogenous expression of various GRD constructs, via gene delivery using a panel of adeno-associated virus (AAV) vectors in MPNST and human Schwann cells (HSCs). We demonstrated that several AAV serotypes achieved favorable transduction efficacies in those cells and a membrane-targeting GRD fused with an H-Ras C-terminal motif (C10) dramatically inhibited the Ras pathway and MPNST cells in a NF1-specific manner. Our results opened up a venue of gene replacement therapy in NF1-related tumors.
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    Ketotifen Modulates Mast Cell Chemotaxis to Kit-Ligand, but Does Not Impact Mast Cell Numbers, Degranulation, or Tumor Behavior in Neurofibromas of Nf1-Deficient Mice
    (American Association for Cancer Research, 2019-12-01) Burks, Ciersten A.; Rhodes, Steven D.; Bessler, Waylan K.; Chen, Shi; Smith, Abbi; Gehlhausen, Jeffrey R.; Hawley, Eric T.; Jiang, Li; Li, Xiaohong; Yuan, Jin; Lu, Qingbo; Jacobsen, Max; Sandusky, George E.; Jones, David R.; Clapp, D. Wade; Blakeley, Jaishri O.; Pediatrics, School of Medicine
    Neurofibromatosis Type 1 (NF1) is one of the most common genetic tumor predisposition syndromes in humans. Mutant NF1 results in dysregulated RAS allowing neoplasms throughout the neuroaxis. Plexiform neurofibromas (pNFs) afflict up to 50% of patients with NF1. They are complex tumors of the peripheral nerve that cause major morbidity via nerve dysregulation and mortality via conversion to malignant sarcoma. Genetically engineered mouse models (GEMMs) of NF1 provide valuable insights for the identification of therapies that have utility in people with pNF. Preclinical studies in GEMMs implicate mast cells and the c-Kit/Kit ligand pathway in pNF tumorigenesis. Kit ligand is a potent chemokine secreted by tumorigenic, Nf1-deficient Schwann cells. Ketotifen is an FDA-approved drug for the treatment of allergic conjunctivitis and asthma that promotes mast cell stabilization and has been used in prior case studies to treat or prevent pNFs. This study investigated the effect of ketotifen on mast cell infiltration and degranulation in the presence and absence of Kit ligand provocation and the effect of ketotifen on shrinking or preventing pNF formation in the Nf1flox/flox;PostnCre+ GEMM. Ketotifen decreased mast cell infiltration in response to exogenous Kit ligand administration, but did not affect mast cell degranulation. Importantly, ketotifen did not reduce mast cells numbers or activity in pNF and did not prevent pNF formation or decrease the volume of established pNF despite administration of pharmacologically active doses. These findings suggest ketotifen has limited use as monotherapy to prevent or reduce pNF burden in the setting of Nf1 mutations.
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    Preclinical assessments of the MEK inhibitor PD-0325901 in a mouse model of neurofibromatosis type 1.
    (Wiley, 2015-10) Jousma, Edwin; Rizvi, Tilat A.; Wu, Jianqiang; Janhofer, David; Dombi, Eva; Dunn, Richard S.; Kim, Mi-Ok; Masters, Andrea R.; Jones, David R.; Cripe, Timothy P.; Ratner, Nancy; Department of Medicine, IU School of Medicine
    Background: Neurofibromatosis type 1 (NF1) is a genetic disorder that predisposes affected individuals to formation of benign neurofibromas, peripheral nerve tumors that can be associated with significant morbidity. Loss of the NF1 Ras-GAP protein causes increased Ras-GTP, and we previously found that inhibiting MEK signaling downstream of Ras can shrink established neurofibromas in a genetically engineered murine model. Procedures: We studied effects of MEK inhibition using 1.5 mg/kg/day PD-0325901 prior to neurofibroma onset in the Nf1 flox/flox;Dhh-Cre mouse model. We also treated mice with established tumors at 0.5 and 1.5 mg/kg/day dosees of PD-0325901. We monitored tumor volumes using MRI and volumetric measurements, and measured pharmacokinetic and pharmacodynamic endpoints. Results: Early administration significantly delayed neurofibroma development as compared to vehicle controls. When treatment was discontinued neurofibromas grew, but no rebound effect was observed and neurofibromas remained significantly smaller than controls. Low dose treatment of mice with PD-0325901 resulted in neurofibroma shrinkage equivalent to that observed at higher doses. Tumor cell proliferation decreased, although less than at higher doses with drug. Tumor blood vessels per area correlated with tumor shrinkage. Conclusions: Neurofibroma development was not prevented by MEK inhibition, beginning at 1 month of age, but tumor size was controlled by early treatment. Moreover, treatment with PD-0325901 at very low doses may shrink neurofibromas while minimizing toxicity. These studies highlight how genetically engineered mouse models can guide clinical trial design.