Superior activity of the combination of histone deacetylase inhibitor LAQ824 and the FLT-3 kinase inhibitor PKC412 against human acute myelogenous leukemia cells with mutant FLT-3.
OBJECTIVE
Mutant FLT-3 receptor tyrosine kinase is a client protein of the molecular chaperone heat shock protein 90 and is commonly present and contributes to the leukemia phenotype in acute myelogenous leukemia (AML). LAQ824, a cinnamyl hydroxamate histone deacetylase inhibitor, is known to induce acetylation and inhibition of heat shock protein 90. Here, we determined the effects of LAQ824 and/or PKC412 (a FLT-3 kinase inhibitor) on the levels of mutant FLT-3 and its downstream signaling, as well as growth arrest and cell-death of cultured and primary human AML cells.


METHODS
The effect of LAQ824 and/or PKC412 treatment was determined on the levels of FLT-3 and phosphorylated (p)-FLT-3, on downstream pro-growth and pro-survival effectors, e.g., p-STAT5, p-AKT, and p-extracellular signal-regulated kinase (ERK) 1/2, and on the cell cycle status and apoptosis in the cultured MV4-11 and primary AML cells with mutant FLT-3.


RESULTS
Treatment with LAQ824 promoted proteasomal degradation and attenuation of the levels of FLT-3 and p-FLT-3, associated with cell cycle G(1)-phase accumulation and apoptosis of MV4-11 cells. This was accompanied by attenuation of p-STAT5, p-AKT, and p-ERK1/2 levels. STAT-5 DNA-binding activity and the levels of c-Myc and oncostatin M were also down-regulated. Cotreatment with LAQ824 and PKC412 synergistically induced apoptosis of MV4-11 cells and induced more apoptosis of the primary AML cells expressing mutant FLT-3. This was also associated with more attenuation of p-FLT-3, p-AKT, p-ERK1/2, and p-STAT5.


CONCLUSIONS
The combination of LAQ824 and PKC412 is highly active against human AML cells with mutant FLT-3, which merits in vivo studies of the combination against human AML.
Department of Interdisciplinary Oncology, Moffitt Cancer Center and Research Institute University of South Florida, Tampa, Florida 33612, USA.
Purva
P
Bali
Prince
P
George
Pamela
P
Cohen
Jianguo
J
Tao
Fei
F
Guo
Celia
C
Sigua
Anasuya
A
Vishvanath
Anna
A
Scuto
Srinivas
S
Annavarapu
Warren
W
Fiskus
Lynn
L
Moscinski
Peter
P
Atadja
Kapil
K
Bhalla
D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D017209:Apoptosis; D015153:Blotting, Western; D002453:Cell Cycle; D045744:Cell Line, Tumor; D004247:DNA / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000008:administration & dosage*; D005091:Exons; D005434:Flow Cytometry; D016193:G1 Phase; D056572:Histone Deacetylase Inhibitors; D006801:Humans; D006877:Hydroxamic Acids / Q000008:administration & dosage*; D015470:Leukemia, Myeloid, Acute / Q000188:drug therapy*; D008894:Milk Proteins / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009154:Mutation; D010766:Phosphorylation; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050799:STAT5 Transcription Factor; D015398:Signal Transduction / Q000187:drug effects; D019311:Staurosporine / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors*; D013997:Time Factors; D015534:Trans-Activators / Q000378:metabolism; D051941:fms-Like Tyrosine Kinase 3
D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; C477361:LAQ824; D008894:Milk Proteins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D050799:STAT5 Transcription Factor; D015534:Trans-Activators; D004247:DNA; C497970:FLT3 protein, human; D020794:Receptor Protein-Tyrosine Kinases; D051941:fms-Like Tyrosine Kinase 3; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D046988:Proteasome Endopeptidase Complex; D019311:Staurosporine; C059539:midostaurin