In vitro and in vivo activity of ATP-based kinase inhibitors AP23464 and AP23848 against activation-loop mutants of Kit.
Oncogenic mutations of the Kit receptor tyrosine kinase occur in several types of malignancy. Juxtamembrane domain mutations are common in gastrointestinal stromal tumors, whereas mutations in the kinase activation loop, most commonly D816V, are seen in systemic mastocytosis and acute myelogenous leukemia. Kit activation-loop mutants are insensitive to imatinib mesylate and have been largely resistant to targeted inhibition. We determined the sensitivities of both Kit mutant classes to the adenosine triphosphate (ATP)-based inhibitors AP23464 and AP23848. In cell lines expressing activation-loop mutants, low-nM concentrations of AP23464 inhibited phosphorylation of Kit and its downstream targets Akt and signal transducer and activator of transcription 3 (STAT3). This was associated with cell-cycle arrest and apoptosis. Wild-type Kit-and juxtamembrane-mutant-expressing cell lines required considerably higher concentrations for equivalent inhibition, suggesting a therapeutic window in which cells harboring D816V Kit could be eliminated without interfering with normal cellular function. Additionally, AP23464 did not disrupt normal hematopoietic progenitor-cell growth at concentrations that inhibited activation-loop mutants of Kit. In a murine model, AP23848 inhibited activation-loop mutant Kit phosphorylation and tumor growth. Thus, AP23464 and AP23848 potently and selectively target activation-loop mutants of Kit in vitro and in vivo and could have therapeutic potential against D816V-expressing malignancies.
Corbin
Amie S
AS
Oregon Health and Science University, Cancer Institute, L592, 3181 SW Sam Jackson Park Rd, Portland, OR 97239, USA.
Demehri
Shadmehr
S
Griswold
Ian J
IJ
Wang
Yihan
Y
Metcalf
Chester A
CA
Sundaramoorthi
Raji
R
Shakespeare
William C
WC
Snodgrass
Joseph
J
Wardwell
Scott
S
Dalgarno
David
D
Iuliucci
John
J
Sawyer
Tomi K
TK
Heinrich
Michael C
MC
Druker
Brian J
BJ
Deininger
Michael W N
MW
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology; D002455:Cell Division / Q000187:drug effects / Q000276:immunology; D045744:Cell Line, Tumor; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D015973:Gene Expression Regulation, Leukemic; D006801:Humans; D066298:In Vitro Techniques; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000187:drug effects; D051379:Mice; D016296:Mutagenesis; D010766:Phosphorylation / Q000187:drug effects; D017434:Protein Structure, Tertiary; D019009:Proto-Oncogene Proteins c-kit / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects
C493107:AP23464; C502390:AP23848; D004791:Enzyme Inhibitors; D000255:Adenosine Triphosphate; D019009:Proto-Oncogene Proteins c-kit