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

• Published in: Cancer research (Chicago, Ill.) Vol. 66; no. 7; pp. 3737 - 3746
• Main Authors: ZHIHONG ZENG, SAMUDIO, Ismael J, PENG HUANG, YILING LU, MILLS, Gordon B, ANDREEFF, Michael, KONOPLEVA, Marina, WEIGUO ZHANG, ESTROV, Zeev, PELICANO, Hélène, HARRIS, David, FROLOVA, Olga, HAIL, Numsen, WENJING CHEN, KORNBLAU, Steven M
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA American Association for Cancer Research 01.04.2006
• Subjects: 3-Phosphoinositide-Dependent Protein Kinases; Animals; Antineoplastic agents; Apoptosis - drug effects; Apoptosis - physiology; Biological and medical sciences; Cell Growth Processes - drug effects; Cell Line, Tumor; fms-Like Tyrosine Kinase 3 - antagonists & inhibitors; fms-Like Tyrosine Kinase 3 - genetics; fms-Like Tyrosine Kinase 3 - metabolism; Hematologic and hematopoietic diseases; Heterocyclic Compounds, 4 or More Rings - pharmacology; Humans; Leukemia, Myeloid, Acute - drug therapy; Leukemia, Myeloid, Acute - enzymology; Leukemia, Myeloid, Acute - genetics; Leukemia, Myeloid, Acute - pathology; Leukemias. Malignant lymphomas. Malignant reticulosis. Myelofibrosis; Medical sciences; Mice; Mitochondria - drug effects; Mitochondria - physiology; Mutation; Pharmacology. Drug treatments; Protein-Serine-Threonine Kinases - antagonists & inhibitors; Protein-Serine-Threonine Kinases - metabolism; Proto-Oncogene Proteins c-akt - antagonists & inhibitors; Proto-Oncogene Proteins c-akt - metabolism; Signal Transduction - drug effects; Tetrazoles - pharmacology; Tumors; U937 Cells; Signal transduction; Mitochondria; Cell death; Dysfunction; Acute; Akt protein kinase; Fms-like tyrosine kinase 3; Malignant hemopathy; Inhibitor; Small molecule; Apoptosis; Acute myelocytic leukemia
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/0008-5472.CAN-05-1278

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.