ABSTRACT
KW-2449, a multikinase inhibitor of FLT3, ABL, ABL-T315I, and Aurora kinase, is under investigation to treat leukemia patients. In this study, we examined its possible modes of action for antileukemic effects on FLT3-activated, FLT3 wild-type, or imatinib-resistant leukemia cells. KW-2449 showed the potent growth inhibitory effects on leukemia cells with FLT3 mutations by inhibition of the FLT3 kinase, resulting in the down-regulation of phosphorylated-FLT3/STAT5, G(1) arrest, and apoptosis. Oral administration of KW-2449 showed dose-dependent and significant tumor growth inhibition in FLT3-mutated xenograft model with minimum bone marrow suppression. In FLT3 wild-type human leukemia, it induced the reduction of phosphorylated histone H3, G(2)/M arrest, and apoptosis. In imatinib-resistant leukemia, KW-2449 contributed to release of the resistance by the simultaneous down-regulation of BCR/ABL and Aurora kinases. Furthermore, the antiproliferative activity of KW-2449 was confirmed in primary samples from AML and imatinib-resistant patients. The inhibitory activity of KW-2449 is not affected by the presence of human plasma protein, such as alpha1-acid glycoprotein. These results indicate KW-2449 has potent growth inhibitory activity against various types of leukemia by several mechanisms of action. Our studies indicate KW-2449 has significant activity and warrants clinical study in leukemia patients with FLT3 mutations as well as imatinib-resistant mutations.
Subject(s)
Cell Proliferation/drug effects , Fusion Proteins, bcr-abl/genetics , Indazoles/pharmacology , Leukemia/genetics , Leukemia/pathology , Piperazines/pharmacology , Protein Kinase Inhibitors/pharmacology , fms-Like Tyrosine Kinase 3/genetics , Animals , Antineoplastic Agents/pharmacology , Cells, Cultured , Drug Evaluation, Preclinical , HL-60 Cells , Humans , Isoleucine/genetics , K562 Cells , Male , Mice , Mice, Inbred C3H , Mice, SCID , Mutation, Missense/physiology , Proto-Oncogene Proteins c-bcr/genetics , Threonine/genetics , Translocation, Genetic/geneticsABSTRACT
Multiple myeloma (MM) is a fatal disease that affects plasma cells. Patients with MM have 1 or more osteolytic lesions in their bone tissues, where insulin-like growth factors (IGFs; IGF-I and IGF-II) are mainly stored. The role of bone-derived IGFs in the development of MM has not been extensively studied because reliable animal models are lacking. We established an animal model using a human MM cell line, RPMI8226, in nonobese diabetic/severe-combined immunodeficient (NOD/SCID) mice implanted with human adult bone (HAB) fragments. Treatment with an anti-human IGF-neutralizing monoclonal antibody, KM1468, inhibited the IGF-I-stimulated phosphorylation of type-I IGF receptors (IGF-IR) in RPMI8226 cells and the activation of the downstream PI3-K/Akt signaling pathway in vitro. KM1468 inhibited IGF-I-mediated RPMI8226 cell growth in a dose-dependent manner. In the NOD/SCID-HAB model, treatment with KM1468 significantly inhibited the growth of RPMI8226 cells (p<0.02). These results indicated that the growth of MM cells was predominantly stimulated not by serum-derived IGFs, but by bone-derived IGFs. Furthermore, the targeting of bone-derived IGFs, using a neutralizing antibody, may offer a new therapeutic strategy for MM.
Subject(s)
Multiple Myeloma/immunology , Multiple Myeloma/physiopathology , Somatomedins/biosynthesis , Somatomedins/immunology , Animals , Antibodies, Monoclonal/immunology , Bone and Bones/physiology , Cell Proliferation , Disease Models, Animal , Humans , Ligands , Male , Mice , Mice, Inbred NOD , Mice, SCID , Phosphorylation , Signal Transduction , Somatomedins/metabolism , Transplantation, HeterologousABSTRACT
Radicicol (1), a macrocyclic antifungal antibiotic, is the lead compound of a novel class of heat shock protein 90 (Hsp90) inhibitors that result in the inhibition or degradation of Hsp90-associated proteins, such as v-src and Raf-1 kinases. New O-carbamoylmethyloxime derivatives of 1 were synthesized and evaluated for their in vitro antiproliferative activities against v-src- and K-ras-transformed cells and for their inhibitory activity against v-src tyrosine kinase. O-(Piperidinocarbonyl)methyloxime 9b, one of the most potent of these derivatives, exhibited more potent antiproliferative activity than 1 and its hydroxime KF25706 (2) and had an IC(50) of 25 nM for the inhibition of v-src kinase activity. Compound 9b was also found to decrease the Raf-1 protein level of KNRK5.2 cells. Furthermore, compound 9b exhibited significant antitumor activity when tested against MX-1 and A431 xenografts in nude mice.
Subject(s)
Antineoplastic Agents/chemical synthesis , Lactones/chemical synthesis , Oximes/chemical synthesis , Piperidines/chemical synthesis , Animals , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Drug Screening Assays, Antitumor , Humans , Lactones/chemistry , Lactones/pharmacology , Macrolides , Mice , Mice, Nude , Mitogen-Activated Protein Kinase 1/metabolism , Neoplasm Transplantation , Oncogene Protein pp60(v-src)/antagonists & inhibitors , Oximes/chemistry , Oximes/pharmacology , Phosphorylation , Piperidines/chemistry , Piperidines/pharmacology , Proto-Oncogene Proteins c-raf/metabolism , Stereoisomerism , Structure-Activity Relationship , Transplantation, Heterologous , Tumor Cells, CulturedABSTRACT
Six structurally related antitumor antibiotics named GEX1 compounds were isolated from a culture broth of Streptomyces sp. GEX1A was identified as a known herbicide, herboxidiene, structurally interested by the tetrahydropyran moiety and the side chain including a conjugated diene. GEX1Q1 to approximately Q5 were determined as novel compounds related to herboxidiene. All GEX1 compounds showed cytotoxicity with IC50 values of 0.0037 to approximately 0.99 microM against human tumor cell lines in vitro, but were not active against both gram-positive and -negative bacteria. Though GEX1A/herboxidiene exhibited antitumor activity in murine tumor-planted mouse models, both GEX1Q3 and GEX1Q5 did not.
Subject(s)
Antibiotics, Antineoplastic/isolation & purification , Streptomyces , Animals , Antibiotics, Antineoplastic/therapeutic use , Fermentation , Humans , Mice , Microbial Sensitivity Tests , Structure-Activity Relationship , Tumor Cells, Cultured/drug effectsABSTRACT
Six GEX1 compounds, GEX1A/herboxidiene and its related 5 novel compounds, were isolated from a culture broth of Streptomyces sp. GEX1 compounds induced both G1 and G2/M arrest in a human normal fibroblast cell line, WI-38. All six compounds up-regulated luciferase reporter gene expression directed by enhancer/promoter of various genes, such as cdc2, IL-2 and SV40 early genes. All GEX1 compounds showed cytotoxic activities in the same order of the up-regulating activities on gene expression, suggesting that these two activities are related. Despite the up-regulating activities on the reporter gene expression, GEX1A/herboxidiene did not enhance the expression of any endogenous genes involved in the cell cycle, proliferation and apoptosis. Although the unique effects of GEX1 compounds on cell cycle and the reporter gene expression were similar to those of trichostatin A (TSA), an inhibitor of histone deacetylase (HDAC), GEX1A/herboxidiene did not affect histone acetylation in cells. In addition, GEX1A/herboxidiene treatment gave rise to the shorter sized transcripts of the cdc25A and cdc2 genes as well as the normal sized ones. These results suggest that GEX1 compounds modulate gene expression by an unknown mechanism.
