Browsing by Author "Hawley, Eric"

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    Brigatinib causes tumor shrinkage in both NF2-deficient meningioma and schwannoma through inhibition of multiple tyrosine kinases but not ALK
    (PLOS, 2021-07-15) Chang, Long-Sheng; Oblinger, Janet L.; Smith, Abbi E.; Ferrer, Marc; Angus, Steven P.; Hawley, Eric; Petrilli, Alejandra M.; Beauchamp, Roberta L.; Riecken, Lars Björn; Erdin, Serkan; Poi, Ming; Huang, Jie; Bessler, Waylan K.; Zhang, Xiaohu; Guha, Rajarshi; Thomas, Craig; Burns, Sarah S.; Gilbert, Thomas S.K.; Jiang, Li; Li, Xiaohong; Lu, Qingbo; Yuan, Jin; He, Yongzheng; Dixon, Shelley A.H.; Masters, Andrea; Jones, David R.; Yates, Charles W.; Haggarty, Stephen J.; La Rosa, Salvatore; Welling, D. Bradley; Stemmer-Rachamimov, Anat O.; Plotkin, Scott R.; Gusella, James F.; Guinney, Justin; Morrison, Helen; Ramesh, Vijaya; Fernandez-Valle, Cristina; Johnson, Gary L.; Blakeley, Jaishri O.; Clapp, D. Wade; Pediatrics, School of Medicine
    Neurofibromatosis Type 2 (NF2) is an autosomal dominant genetic syndrome caused by mutations in the NF2 tumor suppressor gene resulting in multiple schwannomas and meningiomas. There are no FDA approved therapies for these tumors and their relentless progression results in high rates of morbidity and mortality. Through a combination of high throughput screens, preclinical in vivo modeling, and evaluation of the kinome en masse, we identified actionable drug targets and efficacious experimental therapeutics for the treatment of NF2 related schwannomas and meningiomas. These efforts identified brigatinib (ALUNBRIG®), an FDA-approved inhibitor of multiple tyrosine kinases including ALK, to be a potent inhibitor of tumor growth in established NF2 deficient xenograft meningiomas and a genetically engineered murine model of spontaneous NF2 schwannomas. Surprisingly, neither meningioma nor schwannoma cells express ALK. Instead, we demonstrate that brigatinib inhibited multiple tyrosine kinases, including EphA2, Fer and focal adhesion kinase 1 (FAK1). These data demonstrate the power of the de novo unbiased approach for drug discovery and represents a major step forward in the advancement of therapeutics for the treatment of NF2 related malignancies.
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    Genetic disruption of the small GTPase RAC1 prevents plexiform neurofibroma formation in mice with neurofibromatosis type 1
    (Elsevier, 2020-07-17) Mund, Julie A.; Park, SuJung; Smith, Abbi E.; He, Yongzheng; Jiang, Li; Hawley, Eric; Roberson, Michelle J.; Mitchell, Dana K.; Abu-Sultanah, Mohannad; Yuan, Jin; Bessler, Waylan K.; Sandusky, George; Chen, Shi; Zhang, Chi; Rhodes, Steven D.; Clapp, D. Wade; Pediatrics, School of Medicine
    Neurofibromatosis type 1 (NF1) is a common cancer predisposition syndrome caused by mutations in the NF1 tumor suppressor gene. NF1 encodes neurofibromin, a GTPase-activating protein for RAS proto-oncogene GTPase (RAS). Plexiform neurofibromas are a hallmark of NF1 and result from loss of heterozygosity of NF1 in Schwann cells, leading to constitutively activated p21RAS. Given the inability to target p21RAS directly, here we performed an shRNA library screen of all human kinases and Rho-GTPases in a patient-derived NF1-/- Schwann cell line to identify novel therapeutic targets to disrupt PN formation and progression. Rho family members, including Rac family small GTPase 1 (RAC1), were identified as candidates. Corroborating these findings, we observed that shRNA-mediated knockdown of RAC1 reduces cell proliferation and phosphorylation of extracellular signal-regulated kinase (ERK) in NF1-/- Schwann cells. Genetically engineered Nf1flox/flox;PostnCre+ mice, which develop multiple PNs, also exhibited increased RAC1-GTP and phospho-ERK levels compared with Nf1flox/flox;PostnCre- littermates. Notably, mice in which both Nf1 and Rac1 loci were disrupted (Nf1flox/floxRac1flox/flox;PostnCre+) were completely free of tumors and had normal phospho-ERK activity compared with Nf1flox/flox ;PostnCre+ mice. We conclude that the RAC1-GTPase is a key downstream node of RAS and that genetic disruption of the Rac1 allele completely prevents PN tumor formation in vivo in mice.
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    PAK1 inhibition reduces tumor size and extends the lifespan of mice in a genetically engineered mouse model of Neurofibromatosis Type 2 (NF2)
    (Oxford University Press, 2021) Hawley, Eric; Gehlhausen, Jeffrey; Karchugina, Sofiia; Chow, Hoi-Yee; Araiza-Olivera, Daniela; Radu, Maria; Smith, Abbi; Burks, Ciersten; Jiang, Li; Li, Xiaohong; Bessler, Waylan; Masters, Andrea; Edwards, Donna; Burgin, Callie; Jones, David; Yates, Charles; Clapp, D. Wade; Chernoff, Jonathan; Park, Su-Jung; Biochemistry and Molecular Biology, School of Medicine
    Neurofibromatosis Type II (NF2) is an autosomal dominant cancer predisposition syndrome in which germline haploinsufficiency at the NF2 gene confers a greatly increased propensity for tumor development arising from tissues of neural crest derived origin. NF2 encodes the tumor suppressor, Merlin, and its biochemical function is incompletely understood. One well-established function of Merlin is as a negative regulator of group A serine/threonine p21-activated kinases (PAKs). In these studies we explore the role of PAK1 and its closely related paralog, PAK2, both pharmacologically and genetically, in Merlin-deficient Schwann cells and in a genetically engineered mouse model (GEMM) that develops spontaneous vestibular and spinal schwannomas. We demonstrate that PAK1 and PAK2 are both hyper activated in Merlin-deficient murine schwannomas. In preclinical trials, a pan Group A PAK inhibitor, FRAX-1036, transiently reduced PAK1 and PAK2 phosphorylation in vitro, but had insignificant efficacy in vivo. NVS-PAK1-1, a PAK1 selective inhibitor, had a greater but still minimal effect on our GEMM phenotype. However, genetic ablation of Pak1 but not Pak2 reduced tumor formation in our NF2 GEMM. Moreover, germline genetic deletion of Pak1 was well tolerated, while conditional deletion of Pak2 in Schwann cells resulted in significant morbidity and mortality. These data support the further development of PAK1-specific small molecule inhibitors and the therapeutic targeting of PAK1 in vestibular schwannomas and argue against PAK1 and PAK2 existing as functionally redundant protein isoforms in Schwann cells.
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    A proteasome-resistant fragment of NIK mediates oncogenic NF-κB signaling in schwannomas
    (Oxford University Press, 2019-02-15) Gehlhausen, Jeffrey R.; Hawley, Eric; Wahle, Benjamin Mark; He, Yongzheng; Edwards, Donna; Rhodes, Steven D.; Lajiness, Jacquelyn D.; Staser, Karl; Chen, Shi; Yang, Xianlin; Yuan, Jin; Li, Xiaohong; Jiang, Li; Smith, Abbi; Bessler, Waylan; Sandusky, George; Stemmer-Rachamimov, Anat; Stuhlmiller, Timothy J.; Angus, Steven P.; Johnson, Gary L.; Nalepa, Grzegorz; Yates, Charles W.; Clapp, D. Wade; Park, Su-Jung; Pediatrics, School of Medicine
    Schwannomas are common, highly morbid and medically untreatable tumors that can arise in patients with germ line as well as somatic mutations in neurofibromatosis type 2 (NF2). These mutations most commonly result in the loss of function of the NF2-encoded protein, Merlin. Little is known about how Merlin functions endogenously as a tumor suppressor and how its loss leads to oncogenic transformation in Schwann cells (SCs). Here, we identify nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB)-inducing kinase (NIK) as a potential drug target driving NF-κB signaling and Merlin-deficient schwannoma genesis. Using a genomic approach to profile aberrant tumor signaling pathways, we describe multiple upregulated NF-κB signaling elements in human and murine schwannomas, leading us to identify a caspase-cleaved, proteasome-resistant NIK kinase domain fragment that amplifies pathogenic NF-κB signaling. Lentiviral-mediated transduction of this NIK fragment into normal SCs promotes proliferation, survival, and adhesion while inducing schwannoma formation in a novel in vivo orthotopic transplant model. Furthermore, we describe an NF-κB-potentiated hepatocyte growth factor (HGF) to MET proto-oncogene receptor tyrosine kinase (c-Met) autocrine feed-forward loop promoting SC proliferation. These innovative studies identify a novel signaling axis underlying schwannoma formation, revealing new and potentially druggable schwannoma vulnerabilities with future therapeutic potential.
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    Schwannoma development is mediated by Hippo pathway dysregulation and modified by RAS/MAPK signaling
    (ASCI, 2020-10-15) Chen, Zhiguo; Li, Stephen; Mo, Juan; Hawley, Eric; Wang, Yong; He, Yongzheng; Brosseau, Jean-Philippe; Shipman, Tracey; Clapp, D. Wade; Carroll, Thomas J.; Le, Lu Q.; Pediatrics, School of Medicine
    Schwannomas are tumors of the Schwann cells that cause chronic pain, numbness, and potentially life-threatening impairment of vital organs. Despite the identification of causative genes, including NF2 (Merlin), INI1/SMARCB1, and LZTR1, the exact molecular mechanism of schwannoma development is still poorly understood. Several studies have identified Merlin as a key regulator of the Hippo, MAPK, and PI3K signaling pathways; however, definitive evidence demonstrating the importance of these pathways in schwannoma pathogenesis is absent. Here, we provide direct genetic evidence that dysregulation of the Hippo pathway in the Schwann cell lineage causes development of multiple schwannomas in mice. We found that canonical Hippo signaling through the effectors YAP/TAZ is required for schwannomagenesis and that MAPK signaling modifies schwannoma formation. Furthermore, cotargeting YAP/TAZ transcriptional activity and MAPK signaling demonstrated a synergistic therapeutic effect on schwannomas. Our new model provides a tractable platform to dissect the molecular mechanisms underpinning schwannoma formation and the role of combinatorial targeted therapy in schwannoma treatment.