Simultaneous inhibition of PDK1/AKT and Fms-like tyrosine kinase 3 signaling by a small-molecule KP372-1 induces mitochondrial dysfunction and apoptosis in acute myelogenous leukemia.

Abstract

Phosphoinositol-3-kinase (PI3K)/protein kinase B (AKT) and Fms-like tyrosine kinase 3 (FLT3) signaling are aberrantly activated in acute myelogenous leukemia (AML) cells. Constitutively activated AKT and FLT3 regulate leukemia cell survival and resistance to chemotherapy. In this study, we investigated the effects of the novel multiple kinase inhibitor KP372-1 on the survival of AML cell lines and primary AML samples. KP372-1 directly inhibited the kinase activity of AKT, PDK1, and FLT3 in a concentration-dependent manner. Western blot analysis indicated that KP372-1 decreased the phosphorylation of AKT on both Ser(473) and Thr(308); abrogated the phosphorylation of p70S6 kinase, BAD, and Foxo3a via PI3K/AKT signaling; and down-regulated expression of PIM-1 through direct inhibition of FLT3. Treatment of AML cell lines with KP372-1 resulted in rapid generation of reactive oxygen species and stimulation of oxygen consumption, followed by mitochondrial depolarization, caspase activation, and phosphatidylserine externalization. KP372-1 induced pronounced apoptosis in AML cell lines and primary samples irrespective of their FLT3 status, but not in normal CD34(+) cells. Moreover, KP372-1 markedly decreased the colony-forming ability of primary AML samples (IC(50) < 200 nmol/L) with minimal cytotoxic effects on normal progenitor cells. Taken together, our results show that the simultaneous inhibition of critical prosurvival kinases by KP372-1 leads to mitochondrial dysfunction and apoptosis of AML but not normal hematopoietic progenitor cells.

• Authors: Zhihong Zeng, Ismael J Samudio, Weiguo Zhang, Zeev Estrov, Hélène Pelicano, David Harris, Olga Frolova, Numsen Hail Jr, Wenjing Chen, Steven M Kornblau, Peng Huang, Yiling Lu, Gordon B Mills, Michael Andreeff, Marina Konopleva
• Journal: Cancer research (Cancer Res) Vol. 66 Issue 7 Pg. 3737-46 (Apr 01 2006) ISSN: 0008-5472 [Print] United States
• PMID: 16585200 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Heterocyclic Compounds, 4 or More Rings
• KP372-1
• Tetrazoles
• fms-Like Tyrosine Kinase 3
• 3-Phosphoinositide-Dependent Protein Kinases
• PDPK1 protein, human
• Pdpk1 protein, mouse
• Protein Serine-Threonine Kinases
• Proto-Oncogene Proteins c-akt

Topics

• 3-Phosphoinositide-Dependent Protein Kinases
• Animals
• Apoptosis (drug effects, physiology)
• Cell Growth Processes (drug effects)
• Cell Line, Tumor
• Heterocyclic Compounds, 4 or More Rings (pharmacology)
• Humans
• Leukemia, Myeloid, Acute (drug therapy, enzymology, genetics, pathology)
• Mice
• Mitochondria (drug effects, physiology)
• Mutation
• Protein Serine-Threonine Kinases (antagonists & inhibitors, metabolism)
• Proto-Oncogene Proteins c-akt (antagonists & inhibitors, metabolism)
• Signal Transduction (drug effects)
• Tetrazoles (pharmacology)
• U937 Cells
• fms-Like Tyrosine Kinase 3 (antagonists & inhibitors, genetics, metabolism)