title: Novel compounds lowering the cellular isoform of the human prion protein in cultured human cells.
abstract: OBJECTIVE
  Previous studies showed that lowering PrP(C) concomitantly reduced PrP(Sc) in the brains of mice inoculated with prions. We aimed to develop assays that measure PrP(C) on the surface of human T98G glioblastoma and IMR32 neuroblastoma cells. Using these assays, we sought to identify chemical hits, confirmed hits, and scaffolds that potently lowered PrP(C) levels in human brains cells, without lethality, and that could achieve drug concentrations in the brain after oral or intraperitoneal dosing in mice.
  
  
  METHODS
  We utilized HTS ELISA assays to identify small molecules that lower PrP(C) levels by ≥30% on the cell surface of human glioblastoma (T98G) and neuroblastoma (IMR32) cells.
  
  
  RESULTS
  From 44,578 diverse chemical compounds tested, 138 hits were identified by single point confirmation (SPC) representing 7 chemical scaffolds in T98G cells, and 114 SPC hits representing 6 scaffolds found in IMR32 cells. When the confirmed SPC hits were combined with structurally related analogs, >300 compounds (representing 6 distinct chemical scaffolds) were tested for dose-response (EC₅₀) in both cell lines, only studies in T98G cells identified compounds that reduced PrP(C) without killing the cells. EC₅₀ values from 32 hits ranged from 65 nM to 4.1 μM. Twenty-eight were evaluated in vivo in pharmacokinetic studies after a single 10 mg/kg oral or intraperitoneal dose in mice. Our results showed brain concentrations as high as 16.2 μM, but only after intraperitoneal dosing.
  
  
  CONCLUSIONS
  Our studies identified leads for future studies to determine which compounds might lower PrP(C) levels in rodent brain, and provide the basis of a therapeutic for fatal disorders caused by PrP prions.
authors: Institute for Neurodegenerative Diseases, University of California, San Francisco, United States; Department of Neurology, University of California, San Francisco, United States; Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, United States.
authors: B Michael
authors: BM
authors: Silber
authors: Institute for Neurodegenerative Diseases, University of California, San Francisco, United States; Department of Neurology, University of California, San Francisco, United States.
authors: Joel R
authors: JR
authors: Gever
authors: Institute for Neurodegenerative Diseases, University of California, San Francisco, United States; Department of Neurology, University of California, San Francisco, United States.
authors: Satish
authors: S
authors: Rao
authors: Institute for Neurodegenerative Diseases, University of California, San Francisco, United States; Department of Neurology, University of California, San Francisco, United States.
authors: Zhe
authors: Z
authors: Li
authors: Small Molecule Discovery Center, University of California, San Francisco, United States; Department of Pharmaceutical Chemistry, University of California, San Francisco, United States.
authors: Adam R
authors: AR
authors: Renslo
authors: Institute for Neurodegenerative Diseases, University of California, San Francisco, United States.
authors: Kartika
authors: K
authors: Widjaja
authors: Institute for Neurodegenerative Diseases, University of California, San Francisco, United States.
authors: Casper
authors: C
authors: Wong
authors: Institute for Neurodegenerative Diseases, University of California, San Francisco, United States; Department of Neurology, University of California, San Francisco, United States.
authors: Kurt
authors: K
authors: Giles
authors: Institute for Neurodegenerative Diseases, University of California, San Francisco, United States.
authors: Yevgeniy
authors: Y
authors: Freyman
authors: Institute for Neurodegenerative Diseases, University of California, San Francisco, United States.
authors: Manuel
authors: M
authors: Elepano
authors: Department of Pharmaceutical Chemistry, University of California, San Francisco, United States.
authors: John J
authors: JJ
authors: Irwin
authors: Institute for Neurodegenerative Diseases, University of California, San Francisco, United States; Department of Pharmaceutical Chemistry, University of California, San Francisco, United States.
authors: Matthew P
authors: MP
authors: Jacobson
authors: Institute for Neurodegenerative Diseases, University of California, San Francisco, United States; Department of Neurology, University of California, San Francisco, United States. Electronic address: stanley@ind.ucsf.edu.
authors: Stanley B
authors: SB
authors: Prusiner
mesh_terms: D000818:Animals; D001921:Brain; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005453:Fluorescence; D057166:High-Throughput Screening Assays; D006801:Humans; D051379:Mice; D018613:Microscopy, Confocal; D015394:Molecular Structure; D011328:Prions / Q000032:analysis*; D020033:Protein Isoforms; D054852:Small Molecule Libraries / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D013499:Surface Properties; D014018:Tissue Distribution; D014407:Tumor Cells, Cultured
chemical_list: D011328:Prions; D020033:Protein Isoforms; D054852:Small Molecule Libraries
keywords: Creutzfeldt–Jakob disease; Neurodegeneration; PrP(C); PrP(Sc); Prion