title: Preclinical characterization of atiprimod, a novel JAK2 AND JAK3 inhibitor.
abstract: We herein report on the activity of the JAK2/JAK3 small molecule inhibitor atiprimod on mouse FDCP-EpoR cells carrying either wild-type (JAK2 (WT)) or mutant (JAK2 (V617F)) JAK2, human acute megakaryoblastic leukemia cells carrying JAK2 (V617F) (SET-2 cell line), and human acute megakaryocytic leukemia carrying mutated JAK3 (CMK cells). Atiprimod inhibited more efficaciously the proliferation of FDCP-EpoR JAK2 (V617F) (IC(50) 0.42 μM) and SET-2 cells (IC(50) 0.53 μM) than that of CMK (IC(50) 0.79 μM) or FDCP-EpoR JAK2 (WT) cells (IC(50) 0.69 μM). This activity was accompanied by inhibition of the phosphorylation of JAK2 and downstream signaling proteins STAT3, STAT5, and AKT in a dose- and time-dependent manner. Atiprimod-induced cell growth inhibition of JAK2 (V617F)-positive cells was coupled with induction of apoptosis, as evidenced by heightened mitochondrial membrane potential and caspase-3 activity, as well as PARP cleavage, increased turnover of the anti-apoptotic X-linked mammalian inhibitor of apoptosis (XIAP) protein, and inhibition of the pro-apoptotic protein BCL-2 in a time- and dose-dependent manner. Furthermore, atiprimod was more effective at inhibiting the proliferation of peripheral blood hematopoietic progenitors obtained from patients with JAK2 (V617F)-positive polycythemia vera than at inhibiting hematopoietic progenitors from normal individuals (p = 0.001). The effect on primary expanded erythroid progenitors was paralleled by a decrease in JAK2(V617F) mutant allele burden in single microaspirated BFU-E and CFU-GM colonies. Taken together, our data supports the clinical testing of atiprimod in patients with hematologic malignancies driven by constitutive activation of JAK2 or JAK3 kinases.
authors.affiliation: Department of Leukemia, UT MD Anderson Cancer Center, Unit 428, 1515 Holcombe Blvd, Houston TX 77030, USA.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Quintás-Cardama
authors.forename: Taghi
authors.initials: T
authors.lastname: Manshouri
authors.forename: Zeev
authors.initials: Z
authors.lastname: Estrov
authors.forename: David
authors.initials: D
authors.lastname: Harris
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
authors.forename: Amos
authors.initials: A
authors.lastname: Gaikwad
authors.forename: Hagop M
authors.initials: HM
authors.lastname: Kantarjian
authors.forename: Srdan
authors.initials: S
authors.lastname: Verstovsek
mesh_terms: D000483:Alleles; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003114:Colony-Forming Units Assay; D004354:Drug Screening Assays, Antitumor; D015672:Erythroid Precursor Cells / Q000166:cytology / Q000187:drug effects; D006801:Humans; D053614:Janus Kinase 2 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D053616:Janus Kinase 3 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D051379:Mice; D050505:Mutant Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010766:Phosphorylation / Q000187:drug effects; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D050791:STAT Transcription Factors / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013141:Spiro Compounds / Q000494:pharmacology*; D051636:X-Linked Inhibitor of Apoptosis Protein / Q000378:metabolism
chemical_list: D050505:Mutant Proteins; D047428:Protein Kinase Inhibitors; D050791:STAT Transcription Factors; D013141:Spiro Compounds; D051636:X-Linked Inhibitor of Apoptosis Protein; C099015:azaspirane; D011065:Poly(ADP-ribose) Polymerases; D053614:Janus Kinase 2; D053616:Janus Kinase 3; D051057:Proto-Oncogene Proteins c-akt; D053148:Caspase 3