Browsing by Author "Stuhlmiller, Timothy J."

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    FOXA1 and adaptive response determinants to HER2 targeted therapy in TBCRC 036
    (Springer Nature, 2021-05-12) Angus, Steven P.; Stuhlmiller, Timothy J.; Mehta, Gaurav; Bevill, Samantha M.; Goulet, Daniel R.; Olivares-Quintero, J. Felix; East, Michael P.; Tanioka, Maki; Zawistowski, Jon S.; Singh, Darshan; Sciaky, Noah; Chen, Xin; He, Xiaping; Rashid, Naim U.; Chollet-Hinton, Lynn; Fan, Cheng; Soloway, Matthew G.; Spears, Patricia A.; Jefferys, Stuart; Parker, Joel S.; Gallagher, Kristalyn K.; Forero-Torres, Andres; Krop, Ian E.; Thompson, Alastair M.; Murthy, Rashmi; Gatza, Michael L.; Perou, Charles M.; Earp, H. Shelton; Carey, Lisa A.; Johnson, Gary L.; Pediatrics, School of Medicine
    Inhibition of the HER2/ERBB2 receptor is a keystone to treating HER2-positive malignancies, particularly breast cancer, but a significant fraction of HER2-positive (HER2+) breast cancers recur or fail to respond. Anti-HER2 monoclonal antibodies, like trastuzumab or pertuzumab, and ATP active site inhibitors like lapatinib, commonly lack durability because of adaptive changes in the tumor leading to resistance. HER2+ cell line responses to inhibition with lapatinib were analyzed by RNAseq and ChIPseq to characterize transcriptional and epigenetic changes. Motif analysis of lapatinib-responsive genomic regions implicated the pioneer transcription factor FOXA1 as a mediator of adaptive responses. Lapatinib in combination with FOXA1 depletion led to dysregulation of enhancers, impaired adaptive upregulation of HER3, and decreased proliferation. HER2-directed therapy using clinically relevant drugs (trastuzumab with or without lapatinib or pertuzumab) in a 7-day clinical trial designed to examine early pharmacodynamic response to antibody-based anti-HER2 therapy showed reduced FOXA1 expression was coincident with decreased HER2 and HER3 levels, decreased proliferation gene signatures, and increased immune gene signatures. This highlights the importance of the immune response to anti-HER2 antibodies and suggests that inhibiting FOXA1-mediated adaptive responses in combination with HER2 targeting is a potential therapeutic strategy.
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    High-content image-based analysis and proteomic profiling identifies Tau phosphorylation inhibitors in a human iPSC-derived glutamatergic neuronal model of tauopathy
    (Springer Nature, 2021-08-23) Cheng, Chialin; Reis, Surya A.; Adams, Emily T.; Fass, Daniel M.; Angus, Steven P.; Stuhlmiller, Timothy J.; Richardson, Jared; Olafson, Hailey; Wang, Eric T.; Patnaik, Debasis; Beauchamp, Roberta L.; Feldman, Danielle A.; Silva, M. Catarina; Sur, Mriganka; Johnson, Gary L.; Ramesh, Vijaya; Miller, Bruce L.; Temple, Sally; Kosik, Kenneth S.; Dickerson, Bradford C.; Haggarty, Stephen J.; Pediatrics, School of Medicine
    Mutations in MAPT (microtubule-associated protein tau) cause frontotemporal dementia (FTD). MAPT mutations are associated with abnormal tau phosphorylation levels and accumulation of misfolded tau protein that can propagate between neurons ultimately leading to cell death (tauopathy). Recently, a p.A152T tau variant was identified as a risk factor for FTD, Alzheimer's disease, and synucleinopathies. Here we used induced pluripotent stem cells (iPSC) from a patient carrying this p.A152T variant to create a robust, functional cellular assay system for probing pathophysiological tau accumulation and phosphorylation. Using stably transduced iPSC-derived neural progenitor cells engineered to enable inducible expression of the pro-neural transcription factor Neurogenin 2 (Ngn2), we generated disease-relevant, cortical-like glutamatergic neurons in a scalable, high-throughput screening compatible format. Utilizing automated confocal microscopy, and an advanced image-processing pipeline optimized for analysis of morphologically complex human neuronal cultures, we report quantitative, subcellular localization-specific effects of multiple kinase inhibitors on tau, including ones under clinical investigation not previously reported to affect tau phosphorylation. These results demonstrate the potential for using patient iPSC-derived ex vivo models of tauopathy as genetically accurate, disease-relevant systems to probe tau biochemistry and support the discovery of novel therapeutics for tauopathies.
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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.