TY - JOUR
T1 - Inhibition of phosphatidylinositol 3-kinase dephosphorylates BAD and promotes apoptosis in myeloid leukemias
AU - Zhao, S.
AU - Konopleva, M.
AU - Cabreira-Hansen, M.
AU - Xie, Z.
AU - Hu, W.
AU - Milella, M.
AU - Estrov, Z.
AU - Mills, G. B.
AU - Andreeff, M.
N1 - Funding Information:
This work was supported in part by grants from the NIH PO1 CA55164 and CA16672. MA is also supported by the Stringer Professorship for Cancer Treatment and Research.
PY - 2004/2
Y1 - 2004/2
N2 - The phosphatidylinositol 3-kinase (PI3K)/AKT protein kinase pathways is involved in cell growth, proliferation, and apoptosis. The functional activation of PI3K/AKT provides survival signals and blockade of this pathway may facilitate cell death. Down-stream targets of PI3K-AKT include the proapoptotic protein BAD, caspase-9, NFκB, and Forkhead. We have previously reported that BAD is constitutively phosphorylated in primary acute myeloid leukemia (AML) cells, a post-transcriptional modification, which inactivates its proapoptotic function. In this study, we tested the hypothesis that the inhibition of PI3K by LY294002 results in the dephosphorylation of AKT and BAD, and thus promote leukemia cell apoptosis. We investigated the effects of LY294002 in megakaryocytic leukemia-derived MO7E cells, primary AML and normal bone marrow progenitor cells. In MO7E cells. LY294002 reduced AKT kinase activity, induced dephosphorylation of AKT and BAD, and increased apoptosis. Concomitant inhibition of mitogen-activated protein kinase signaling or combination with all-trans retinoic acid further enhanced apoptosis of leukemic cells. In primary AML samples, clonogenic cell growth was significantly reduced. Normal hematopoietic progenitors were less affected, suggesting preferential targeting of leukemia cells. In conclusion, the data suggest that the inhibition of the PI3K/AKT signaling pathway restores apoptosis in AML and may be explored as a novel target for molecular therapeutic in AML.
AB - The phosphatidylinositol 3-kinase (PI3K)/AKT protein kinase pathways is involved in cell growth, proliferation, and apoptosis. The functional activation of PI3K/AKT provides survival signals and blockade of this pathway may facilitate cell death. Down-stream targets of PI3K-AKT include the proapoptotic protein BAD, caspase-9, NFκB, and Forkhead. We have previously reported that BAD is constitutively phosphorylated in primary acute myeloid leukemia (AML) cells, a post-transcriptional modification, which inactivates its proapoptotic function. In this study, we tested the hypothesis that the inhibition of PI3K by LY294002 results in the dephosphorylation of AKT and BAD, and thus promote leukemia cell apoptosis. We investigated the effects of LY294002 in megakaryocytic leukemia-derived MO7E cells, primary AML and normal bone marrow progenitor cells. In MO7E cells. LY294002 reduced AKT kinase activity, induced dephosphorylation of AKT and BAD, and increased apoptosis. Concomitant inhibition of mitogen-activated protein kinase signaling or combination with all-trans retinoic acid further enhanced apoptosis of leukemic cells. In primary AML samples, clonogenic cell growth was significantly reduced. Normal hematopoietic progenitors were less affected, suggesting preferential targeting of leukemia cells. In conclusion, the data suggest that the inhibition of the PI3K/AKT signaling pathway restores apoptosis in AML and may be explored as a novel target for molecular therapeutic in AML.
KW - AML and apoptosis
KW - BAD phosphorylation
KW - LY294002
KW - MO7E
KW - PI3K-AKT
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U2 - 10.1038/sj.leu.2403220
DO - 10.1038/sj.leu.2403220
M3 - Article
C2 - 14628071
AN - SCOPUS:1242285048
SN - 0887-6924
VL - 18
SP - 267
EP - 275
JO - Leukemia
JF - Leukemia
IS - 2
ER -