Glycogen synthase kinase--3β inhibitors suppress leukemia cell growth.
OBJECTIVE
The objective of this study was to investigate the effect of small molecule inhibitors of glycogen synthase kinase-3β (GSK-3β) on leukemia cell growth and survival.


METHODS
Analysis of cytotoxicity and cell proliferation was conducted using the MTS assay, cell-cycle analysis, and division tracking. Apoptosis was investigated by Annexin-V/7-aminoactinomycin D and caspase-3 expression. The effect of GSK-3β inhibitors was also tested in vivo in an animal model of leukemia. Gene expression analysis was performed to identify the genes modulated by GSK-3β inhibition in leukemia cells.


RESULTS
GSK-3β inhibitors suppress cell growth and induce apoptosis in seven leukemia cell lines of diverse origin, four acute myeloid leukemia, one myelodysplastic syndrome, and one acute lymphoblastic leukemia samples. GSK-3β inhibitors are cytotoxic for rapidly dividing clonogenic leukemia blasts, and higher doses of the inhibitors are needed to eliminate primitive leukemia progenitor/stem cells. Slow cell-division rate, low drug uptake, and interaction with bone marrow stroma make leukemia cells more resistant to apoptosis induced by GSK-3β inhibitors. Global gene expression analysis combined with functional approaches identified multiple genes and specific signaling pathways modulated by GSK-3β inhibition. An important role for Bcl2 in the regulation of apoptosis induced by GSK-3β inhibitors was defined by expression analysis and confirmed by using pharmacological inhibitors of the protein. In vivo administration of GSK-3β inhibitors delayed tumor formation in a mouse leukemia model. GSK-3β inhibitors did not affect hematopoietic recovery following irradiation.


CONCLUSIONS
Our data support further evaluation of GSK-3β inhibitors as promising novel agents for therapeutic intervention in leukemia and warrant clinical investigation in leukemia patients.
Song
Emma Y
EY
Sydney Cord and Marrow Transplant Facility, Centre for Children's Cancer and Blood Disorders, Sydney Children's Hospital, Sydney, Australia.
Palladinetti
Patricia
P
Klamer
Guy
G
Ko
Kap-Hyoun
KH
Lindeman
Robert
R
O'Brien
Tracey A
TA
Dolnikov
Alla
A
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D018922:HL-60 Cells; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D019169:Jurkat Cells; D020014:K562 Cells; D007938:Leukemia / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D051379:Mice; D008807:Mice, Inbred BALB C; D016688:Mice, Inbred NOD; D008819:Mice, Nude; D016513:Mice, SCID; D010091:Oximes / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020298:U937 Cells; D023041:Xenograft Model Antitumor Assays
C483321:6-bromoindirubin-3'-oxime; D004791:Enzyme Inhibitors; D007211:Indoles; D010091:Oximes; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D038362:Glycogen Synthase Kinase 3