title: Phenothiazines induce PP2A-mediated apoptosis in T cell acute lymphoblastic leukemia.
abstract: T cell acute lymphoblastic leukemia (T-ALL) is an aggressive cancer that is frequently associated with activating mutations in NOTCH1 and dysregulation of MYC. Here, we performed 2 complementary screens to identify FDA-approved drugs and drug-like small molecules with activity against T-ALL. We developed a zebrafish system to screen small molecules for toxic activity toward MYC-overexpressing thymocytes and used a human T-ALL cell line to screen for small molecules that synergize with Notch inhibitors. We identified the antipsychotic drug perphenazine in both screens due to its ability to induce apoptosis in fish, mouse, and human T-ALL cells. Using ligand-affinity chromatography coupled with mass spectrometry, we identified protein phosphatase 2A (PP2A) as a perphenazine target. T-ALL cell lines treated with perphenazine exhibited rapid dephosphorylation of multiple PP2A substrates and subsequent apoptosis. Moreover, shRNA knockdown of specific PP2A subunits attenuated perphenazine activity, indicating that PP2A mediates the drug's antileukemic activity. Finally, human T-ALLs treated with perphenazine exhibited suppressed cell growth and dephosphorylation of PP2A targets in vitro and in vivo. Our findings provide a mechanistic explanation for the recurring identification of phenothiazines as a class of drugs with anticancer effects. Furthermore, these data suggest that pharmacologic PP2A activation in T-ALL and other cancers driven by hyperphosphorylated PP2A substrates has therapeutic potential.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Gutierrez
authors.forename: Li
authors.initials: L
authors.lastname: Pan
authors.forename: Richard W J
authors.initials: RW
authors.lastname: Groen
authors.forename: Frederic
authors.initials: F
authors.lastname: Baleydier
authors.forename: Alex
authors.initials: A
authors.lastname: Kentsis
authors.forename: Jason
authors.initials: J
authors.lastname: Marineau
authors.forename: Ruta
authors.initials: R
authors.lastname: Grebliunaite
authors.forename: Elena
authors.initials: E
authors.lastname: Kozakewich
authors.forename: Casie
authors.initials: C
authors.lastname: Reed
authors.forename: Francoise
authors.initials: F
authors.lastname: Pflumio
authors.forename: Sandrine
authors.initials: S
authors.lastname: Poglio
authors.forename: Benjamin
authors.initials: B
authors.lastname: Uzan
authors.forename: Paul
authors.initials: P
authors.lastname: Clemons
authors.forename: Lynn
authors.initials: L
authors.lastname: VerPlank
authors.forename: Frank
authors.initials: F
authors.lastname: An
authors.forename: Jason
authors.initials: J
authors.lastname: Burbank
authors.forename: Stephanie
authors.initials: S
authors.lastname: Norton
authors.forename: Nicola
authors.initials: N
authors.lastname: Tolliday
authors.forename: Hanno
authors.initials: H
authors.lastname: Steen
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Weng
authors.forename: Huipin
authors.initials: H
authors.lastname: Yuan
authors.forename: James E
authors.initials: JE
authors.lastname: Bradner
authors.forename: Constantine
authors.initials: C
authors.lastname: Mitsiades
authors.forename: A Thomas
authors.initials: AT
authors.lastname: Look
authors.forename: Jon C
authors.initials: JC
authors.lastname: Aster
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D017209:Apoptosis; D045744:Cell Line, Tumor; D002470:Cell Survival; D002846:Chromatography, Affinity; D004195:Disease Models, Animal; D018492:Dopamine Antagonists / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D013058:Mass Spectrometry; D051379:Mice; D010546:Perphenazine / Q000737:chemistry; D010640:Phenothiazines / Q000737:chemistry*; D010766:Phosphorylation; D010858:Pigmentation; D054218:Precursor T-Cell Lymphoblastic Leukemia-Lymphoma / Q000378:metabolism* / Q000473:pathology*; D054648:Protein Phosphatase 2 / Q000378:metabolism*; D040901:Proteomics; D051880:Receptors, Notch / Q000378:metabolism; D013997:Time Factors; D015027:Zebrafish
chemical_list: D018492:Dopamine Antagonists; D010640:Phenothiazines; D051880:Receptors, Notch; D054648:Protein Phosphatase 2; D010546:Perphenazine