Research Areas Defined

The Washington University Neurofibromatosis (NF) Center uses a team approach to understand the roles of the NF genes in health and disease. This team is composed of clinicians and laboratory scientists focused on accelerating the pace of scientific discovery and its application to the care of individuals with NF.Their mission is to galvanize and promote research on NF, achieving significant breakthroughs in the diagnosis and treatment of nervous system tumors and establishing Washington University as an international beacon for NF research.A cross-disciplinary endeavor, the Washington University NF Center eliminates obstacles to research and establishes a framework for innovative scientific collaboration among investigators using cutting-edge research and medical technologies. The Washington University NF Center also provides advanced care for people with NF. Areas of intense focus include the following four aspects of our team’s neurofibromatosis research efforts.

Predictive value of café-au-lait macules for the diagnosis of neurofibromatosis type 1 (NF1)

Children with NF1 often come to medical attention when birthmarks called café-au-lait macules are found on their skin. However, it is not known whether the presence of these birthmarks can accurately predict who will develop NF1 or what features of NF1 they will have. Studies are ongoing with Dr. Susan Mallory and her colleagues in Dermatology to define the utility of café-au-lait macule shape and number in determining who will eventually be diagnosed with NF1. These investigations are designed to better characterize the dermatologic (skin) features associated with NF1 and understand their clinical importance in the management of children suspected of having this condition.

Additional Reading: Nunley KS, Gao F, Albers AC, Bayliss SJ, Gutmann DH: Predictive value of café-au-lait macules at initial consultation in the diagnosis of neurofibromatosis type 1. Arch Dermat. 145:883-887, 2009.

Visual loss in children with neurofibromatosis type 1 (NF1)-associated optic glioma

While 15-20% of children with NF1 will develop a low-grade brain tumor involving the optic nerve called an optic pathway glioma, it isnot known whether the patient age, gender, or tumor location can be used to predict who will require treatment. Moreover, it is not clear whether some groups of children with NF1-associated optic gliomas are at higher risk for vision loss or treatment failure. As part of an international consortium, Dr. Gutmann and his colleagues are studying the impact of chemotherapy on vision in children with NF1. In addition, these investigations are aimed at identifying risk factors for poor outcome in children with optic pathway gliomas.

Additional Reading:Listernick R, Ferner RE, Liu GT, Gutmann DH: Optic pathway gliomas in neurofibromatosis-1: Controversies and recommendations. Ann Neurol. 61:189-98, 2007.

Gutmann DH, Listernick R, Ferner RE: Screening for symptomatic optic pathway glioma in children with neurofibromatosis type 1. Eye 25:818, 2011.Fisher MJ, Loguidice M, Gutmann DH, Listernick R, Ferner RE, Ullrich NJ, Packer RJ, Tabori U, Hoffman RO, Ardern-Holmes SL, Hummel TR, Hargrave DR, Boufet E, Charrow J, Bilaniuk LT, Balcer LJ, Liu GT: Visual Outcomes in Children with Neurofibromatosis Type 1 Associated Optic Pathway Glioma Following Chemotherapy: A Multi-center Retrospective Analysis. Neuro-Oncology (in press).

Genetic predictors of brain tumor formation in children with neurofibromatosis type 1 (NF1)

While current genetic testing can determine with great accuracy whether a child has NF1, it cannot provide prognostic information regarding the development of specific features of the condition. In this regard, we are unable to identify children with NF1 at highest risk for the development of brain tumors (optic pathway gliomas). Dr. Joshua Rubin in the Department of Pediatrics is spearheading an international study using advanced genomic methods to identify subtle DNA changes that predict the development of brain tumors in children with NF1. His pioneering efforts have begun to reveal genomic regions associated with NF1 glioma formation. Future studies may lead to the development of DNA markers for predictive genetic testing in children with NF1.

Advanced imaging of optic gliomas in mice and children with neurofibromatosis type 1 (NF1)

While current brain imaging can clearly identify brain tumors in children with NF1, they do not provide predictive information about the clinical behavior of the tumor. Over the past several years, new imaging modalities have been developed which offer the potential to identify brain tumors with more aggressive clinical behavior. Dr. Joshua Shimony in the Department of Radiology is currently employing one of these novel imaging methods, called functional connectivity MRI, to determine whether this advanced imaging technique can predict optic glioma growth and vision decline in children with NF1. Dr. Shimony and his colleagues are currently enrolling new patients for this exciting study. In addition, Dr. Joel Garbow in the Department of Chemistry is working with investigators in the Washington University NF Center to discover more refined imaging modalities using Nf1 mouse strains which one day might be evaluated in children with NF1.

Additional Reading:Banerjee D, Hegedus B, Gutmann DH, Garbow JR: Detection and measurement of neurofibromatosis-1 mouse optic glioma in vivo. Neuroimage 35:1434-7, 2007.

Jost SC, Ackerman JW, Garbow JR, Manwaring LP, Gutmann DH, McKinstry RC: Diffusion-weighted and dynamic contrast-enhanced imaging as markers of clinical behavior in children with optic pathway glioma. Pediatric Radiology 38:1293-1299, 2008.Dorward IG, Luo J, Perry A, Gutmann DH, Mansur DB, Rubin JB, Leonard JR: Post-operative imaging surveillance in pediatric pilocytic astrocytomas. J. Neurosurg. Ped. 6:346-52, 2010.

Preclinical evaluation of new brain tumor therapies in Nf1 genetically-engineered mice

After the identification of the NF1 gene and its protein (neurofibromin), it became possible to envision a time when new drug therapies for NF1-associated tumors might replace the missing function of neurofibromin. Over the past decade, several promising candidate compounds have been identified, which need to be evaluated in model organisms prior to the application to children and adults with NF1. To this end, Dr. David Gutmann and his colleagues in the Washington University NF Center have an active research program to evaluate new drugs for the treatment of optic glioma using Nf1 genetically-engineered mice. These studies are designed to rapidly test the most promising candidate drugs prior to their evaluation in children with NF1. One such drug, rapamycin, is now in clinical trials for children with NF1-associated glioma. Additional compounds are currently being evaluated in several Nf1 genetically-engineered mice with optic glioma.

Additional Reading:Gutmann DH, Hunter-Schaedle K, Shannon KM:

Harnessing preclinical mouse models to inform human clinical cancer trials. J Clin Invest. 116:847-852, 2006.

Hegedus B, Banerjee D, Yeh T-H, Rothermich S, Perry A, Rubin JB, Garbow JR, Gutmann DH: Preclinical cancer therapy in a mouse model of neurofibromatosis-1 optic glioma. Cancer Res. 68:1520-8, 2008.Banerjee S, Gianino SM, Gao F, Christians U, Gutmann DH: Interpreting mammalian target of rapamycin and cell growth inhibition in a genetically-engineered mouse model of Nf1-deficient astrocytes. Mol Cancer Ther 10:279-91, 2011.

Understanding the role of the tumor microenvironment in brain tumor formation and growth

Brain tumors are composed of both cancerous and non-cancerous cells. Previous studies in Dr. David Gutmann’s laboratory revealed that the non-cancerous cells may a critical role in the development and growth of optic gliomas in Nf1 genetically engineered mice. To further define the contribution of these non-cancerous cells to glioma growth, investigators at the Washington University NF Center are working together to combine their individual expertise. Dr. Gutmann and his colleagues showed that immune system-like cells, called microglia, are abundant in both human and mouse optic gliomas and that these cells are critical for optic glioma growth in Nf1 genetically-engineered mice. These exciting findings suggest that new targets for therapeutic drug design might result from the identification of the factors made by glioma-associated microglia. Teaming with Drs. Elaine Mardis, Joshua Rubin, Jeffrey Leonard, and David Piwnica-Worms, Dr. Gutmann is directing studies aimed at discovering these critical microglia growth factors using advanced RNA sequencing methods developed at the Genome Institute at Washington University. The results from these studies may one day lead to treatments that target these non-cancerous cells in the tumor microenvironment.

Additional Reading:Daginakatte GC, Gutmann DH: Neurofibromatosis-1 (Nf1) heterozygous brain microglia elaborate paracrine factors that promote Nf1-deficient astrocyte and glioma growth. Hum Mol Genet. 16:1098-1112, 2007.

Daginakatte GC, Gianino SM, Zhao NW, Parsadanian AS, Gutmann DH: Increased JNK signaling in Neurofibromatosis-1 (Nf1) heterozygous microglia drives microglia activation and promotes optic glioma proliferation. Cancer Res. 68:10358-10366, 2008.Simmons GW, Pong WW, Emnett RJ, White CR, Gianino SM, Rodriguez FJ, Gutmann DH: Neurofibromatosis-1 heterozygosity increases microglia in a spatially- and temporally-restricted pattern relevant to mouse optic glioma formation and growth. J Neuropathol Exp Neurol. 70:51-62, 2011.

Defining the role of the neurofibromatosis type 1 (NF1) gene in normal brain development

The observation that children with NF1 have learning, memory, and behavioral problems suggests that the NF1protein neurofibromin is important in normal brain development and function. To better understand the role of neurofibromin in normal brain development, Dr. Gutmann and his colleagues are using novel strains of genetically-engineered mice. These studies are aimed at determining the mechanism by which neurofibromin regulates the growth of progenitor cells (neural stem cells) and their differentiation into neurons, astrocytes, and oligodendrocytes. The goal of these studies are to determine exactly how neurofibromin regulates normal brain development and function with an eye towards future treatments that leverage these new insights.

Additional Reading:Dasgupta B, Gutmann DH: Neurofibromin regulates neural stem cell proliferation, survival, and astroglial differentiation in vitro and in vivo. J Neurosci. 25:5584-94, 2005.

Hegedus B, Dasgupta B, Shin JE, Emnett RJ, Hart-Mahon EK, Elghazi L, Bernal-Mizrachi E, Gutmann DH: Neurofibromatosis-1 regulates neuronal and glial cell differentiation from neuroglial progenitors in vivo by both cAMP- and Ras-dependent mechanisms. Cell Stem Cell 1:443-457, 2007.Hegedus B, Yeh T-H, Lee DY, Emnett RJ, Li J, Gutmann DH: Neurofibromin regulates somatic growth through the hypothalamic-pituitary axis. Hum Mol Genet. 17:2955-2966, 2008.

Yeh T-H, Lee DY, Gianino SM, Gutmann DH: Microarray analyses reveal regional astrocyte heterogeneity with implications for neurofibromatosis type 1 (NF1)-regulated glial proliferation. GLIA 57:1239-49, 2009.

Lee DY, Yeh T-H, Emnett RJ, White CR, Gutmann DH: Neurofibromatosis-1 regulates neuroglial progenitor proliferation and glial differentiation in a brain region-specific manner. Genes & Development 24:2317-29, 2010.

Developing new treatments for attention deficits in children with neurofibromatosis type 1 (NF1)

Nearly two-thirds of all children with NF1 exhibit problems with attention and impulsivity. In an effort to develop new treatments for these common problems, cross-disciplinary studies in the Washington University NF Center are leveraging Nf1 genetically-engineered mice. These investigations are designed to understand the molecular and cellular basis for attention deficits in NF1. Spearheaded by Dr. David Wozniak in the Department of Psychiatry, these experiments have already led to the development of behavioral tests in mice suitable for preclinical drug evaluation. Working with Dr. Robert Mach in the Department of Radiology, Drs. Gutmann and Wozniak have recently applied positron emission tomography (PET) imaging to the preclinical evaluation of promising drugs for attention deficit. Future studies will combine imaging and behavior assessments to identify and test new candidate treatments for NF1-associated attention deficit.

Additional Reading:Brown JA, Emnett RJ, White C, Yuede C, Conyers S, O’Malley K, Wozniak DF, Gutmann DH: Reduced striatal dopamine underlies the attention system dysfunction in neurofibromatosis-1 mutant mice. Human Mol Genet. 19:4515-28, 2010.

Brown JA, Xu J, Diggs-Andrews KA, Wozniak DF, Mach RH, Gutmann DH: PET imaging for attention deficit preclinical drug testing in neurofibromatosis-1 mice. Exp Neurol 232:333-8, 2011.

Identifying new treatments for neurofibromatosis type 1 (NF1)-associated tumors

With the identification of the NF1 gene in 1990, it became possible to define the mechanism by which the NF1 protein (neurofibromin) controls cell growth. Over the past decade, Dr. Gutmann and his colleagues have focused on determining the precise way neurofibromin regulates the growth of brain cells. Using a team effort involving numerous investigators at the Washington University NF Center, we aim to discover new drugs for the treatment of tumors arising in children and adults with NF1. Drs. David Piwnica-Worms, Joshua Rubin, Jason Weber, and David Gutmann have been working together for the past seven years to identify such promising compounds and determine how they block NF1-associated tumor growth. These studies have already led to the identification of rapamycin drugs now in clinical trial for plexiform neurofibromas and brain tumors as well as compounds that restore normal cyclic AMP signaling in NF1-associated tumors in mice. We continue to refine these targeted treatments to optimally inhibit tumor growth with minimal effects on the normal brain.

Additional Reading:Dasgupta B, Yi Y, Chen DY, Weber JD, Gutmann DH: Proteomic analysis reveals hyperactivation of the mTOR pathway in NF1-associated human and mouse brain tumors. Cancer Res. 65:2755-60, 2005.

Sandsmark DK, Zhang H, Hegedus B, Pelletier CL, Weber JD, Gutmann DH: Nucleophosmin mediates mammalian target of rapamycin-dependent actin cytoskeleton dynamics and proliferation in neurofibromin-deficient astrocytes. Cancer Res. 67:4790-9, 2007.

Warrington NM, Woerner BM, Daginakatte GC, Dasgupta B, Perry A, Gutmann DH, Rubin JB: Spatiotemporal differences in CXCL12 expression and cyclic AMP underlie the unique pattern of optic glioma growth in neurofibromatosis type 1. Cancer Res. 67:8588-8595, 2007.

Banerjee S, Byrd JN, Gianino SM, Harpstrite SE, Rodriguez FJ, Tuskan RG, Reilly KM, Piwnica-Worms DR, Gutmann DH: Neurofibromin controls cell growth by regulating STAT3 activity in vitro and in vivo. Cancer Res 70:1356-66, 2010.

Sun T, Gianino SM, Jackson E, Piwnica-Worms D, Gutmann DH, Rubin JB: CXCL12 alone is insufficient for gliomagenesis in Nf1 mutant mice. J. Neuroimmunol. 224:108-13, 2010.

Warrington NM, Gianino SM, Jackson E, Goldhoff P, Garbow JR, Piwnica-Worms D, Gutmann DH, Rubin JB: Cyclic AMP suppression is sufficient to induce gliomagenesis in a mouse model of neurofibromatosis-1. Cancer Res 70:5717-27, 2010.

Banerjee S, Crouse NR, Emnett RJ, Gianino SM, Gutmann DH: Neurofibromatosis-1 regulates mTOR-mediated astrocyte growth and glioma formation in a TSC/Rheb-independent manner. Proc Natl Acad Sci USA 108:15996-6001, 2011.

Function of the neurofibromatosis type 1 (NF1) gene in brain nerve cells

Individuals with NF1 are prone to learning disabilities, behavioral problems, seizures, and motor delays – all indicative of impairments in normal nerve cell (neuron) function. Dr. Gutmann and his colleagues are leading studies to understand how the NF1 protein (neurofibromin) controls the function of neurons in the brain. These investigations have revealed that reduced neurofibromin function in the brain leads to impaired neuron lengths and survival, which reflects the role of neurofibromin in controlling cyclic AMP levels. Current efforts are directed at defining the mechanism underlying neurofibromin cyclic AMP regulation in neurons and identifying drugs capable of restoring normal neuron function.

Additional Reading:Hegedus B, Hughes WF, Garbow JR, Gianino S, Banerjee D, Kim K, Ellisman MH, Brantley MA, Gutmann DH: Optic nerve dysfunction in a mouse model of neurofibromatosis-1 optic glioma. J Neuropathol Exp Neurol. 68:542-551, 2009.

Brown JA, Gianino SM, Gutmann DH: Defective cyclic AMP generation underlies the sensitivity of central nervous system neurons to neurofibromatosis-1 heterozygosity. J Neurosci 30:5579-89, 2010. Brown JA, Diggs-Andrews KA, Gianino SM, Gutmann DH: Neurofibromatosis-1 heterozygosity impairs CNS neuronal morphology in a cAMP/PKA/ROCK-dependent manner. Molecular and Cellular Neuroscience 49:13-22, 2012.

Understanding the genetics of neurofibromatosis type 1 (NF1)-associated brain tumors

The development of new drugs for NF1-associated brain tumors requires that a comprehensive analysis of these tumors in both mice and humans. To accomplish this goal, Dr. Gutmann and his colleagues are performing detailed studies to identify the types of cells present in mouse optic gliomas and the interactions between these various cells in controlling brain tumor growth. In addition, Drs. Elaine Mardis and her team at the Genome Institute at Washington University are applying advanced whole genome sequencing methods to NF1-associated human tumors to comprehensively define the genetic changes present in these complex tumors.

Additional Reading:Rodriguez FJ, Perry A, Gutmann DH, O’Neill BP, Leonard J, Bryant S, Giannini C: Gliomas in neurofibromatosis type 1: a clinicopathologic study of 100 patients. J Neuropath Exp Neurol. 67:240-9, 2008.

Rodriguez FJ, Giannini C, Asmann YW, Sharma MK, Perry A, Tibbetts KM, Jenkins RB, Scheithauer BW, Anant S, Jenkins S, Eberhart EG, Sarkaria JN, Gutmann DH: Gene expression profiling of NF1-associated and sporadic pilocytic astrocytomas identifies ALDH1L1 as an underexpressed candidate biomarker in aggressive astrocytoma subtypes. J Neuropath Exp Neurol. 67:1194-1204, 2008.Tibbetts KM, Emnett RJ, Gao F, Perry A, Gutmann DH, Leonard J: Histopathologic predictors of pilocytic astrocytoma event-free survival. Acta Neuropathologica 117:657-665, 2009.

Kim K-Y, Ju WK, Hegedus B, Gutmann DH, Ellisman ME: Ultrastructural Characterization of the Optic Pathway in a Mouse Model of Neurofibromatosis-1 Optic Glioma. Neuroscience 170:178-88, 2010.

Determining the role of the neurofibromatosis type 2 (NF2) gene in ependymoma formation

Individuals with NF2 are prone to the development of spinal cord tumors, called ependymomas. These glial cell tumors arise from progenitor cells in the spinal cord. In order to develop more targeted treatments for these tumors, Dr. David Gutmann and his colleagues have employed Nf2 genetically-engineered mice to define the mechanism underlying NF2 protein (merlin) regulation of spinal cord glial cell and progenitor cell growth. These studies have revealed new ways that merlin controls cell growth in the nervous system. Current investigations are focused on merlin function in spinal cord progenitor cells in an effort to identify new therapies for NF2-associated ependymoma.

Additional Reading:Lau Y-KI, Murray L, Houshmandi SS, Xu Y, Gutmann DH, Yu Q: Merlin is a potent inhibitor of glioma growth. Cancer Res. 68:5733-5742, 2008.

Houshmandi SS, Emnett RJ, Giovannini M, Gutmann DH: The neurofibromatosis-2 protein, merlin, regulates glial cell growth in an ErbB2- and Src-dependent manner. Mol Cell Biol. 29:1472-86, 2009.

Defining the spectrum of clinical problems in children with neurofibromatosis type 1 (NF1)

While much clinical research has focused on tumors, children with NF1 can have a variety of problems with behavior, motor coordination, and attention. To better understand the impact of these issues on the lives of children with NF1, several investigators in the Washington University NF Center have initiated clinical studies to define the spectrum of attention deficits, developmental delays, short stature, and sleep problems in children with NF1. These initial studies will provide researchers with a more in-depth understanding of these clinical features and will lead to future investigations aimed at developing more personalized treatments for children with NF1 who have these specific problems.

Additional Reading:Templer AK, Titus JB, Gutmann DH: A neuropsychological perspective on attention problems in neurofibromatosis type 1. J Attention Disorders (in press).

Isenberg JC, Templer A, Gao F, Titus JB, Gutmann DH: Attention skills in children with neurofibromatosis type 1. J. Child Neurol (in press).Soucy EA, Gao F, Gutmann DH, Dunn CM: Developmental delays in children with neurofibromatosis type 1. J Child Neurology (in press).