Subject(s)
B-Lymphocytes/metabolism , Chromosomes, Human, Pair 22/genetics , Precursor Cell Lymphoblastic Leukemia-Lymphoma/epidemiology , Antineoplastic Agents/therapeutic use , Gene Expression Regulation, Neoplastic/genetics , Humans , Incidence , Middle Aged , Philadelphia Chromosome , Precursor Cell Lymphoblastic Leukemia-Lymphoma/drug therapy , Precursor Cell Lymphoblastic Leukemia-Lymphoma/genetics , Protein Kinase Inhibitors/therapeutic use , Protein-Tyrosine Kinases/genetics , Signal Transduction/geneticsSubject(s)
Benzothiazoles/therapeutic use , Genotype , Karyotyping , Leukemia, Myeloid, Acute/drug therapy , Phenylurea Compounds/therapeutic use , Benzothiazoles/pharmacology , Humans , Leukemia, Myeloid, Acute/genetics , Mutation , Phenylurea Compounds/pharmacology , fms-Like Tyrosine Kinase 3/geneticsABSTRACT
As chronic myeloid leukemia (CML) progresses from the chronic phase to blast crisis, the levels of BCR-ABL increase. In addition, blast-transformed leukemic cells display enhanced resistance to imatinib in the absence of BCR-ABL-resistance mutations. In this study, we show that when BCR-ABL-transformed cell lines were selected for imatinib resistance in vitro, the cells that grew out displayed a higher BCR-ABL expression comparable to the increase seen in accelerated forms of the disease. This enhanced expression of BCR-ABL was associated with an increased rate of glycolysis but with a decreased rate of proliferation. The higher level of BCR-ABL expression in the selected cells correlated with a nonhypoxic induction of hypoxia-inducible factor-1alpha (HIF-1alpha) that was required for cells to tolerate enhanced BCR-ABL signaling. HIF-1alpha induction resulted in an enhanced rate of glycolysis but with reduced glucose flux through both the tricarboxylic acid cycle and the oxidative arm of the pentose phosphate pathway (PPP). The reduction in oxidative PPP-mediated ribose synthesis was compensated by the HIF-1alpha-dependent activation of the nonoxidative PPP enzyme, transketolase, in imatinib-resistant CML cells. In both primary cultures of cells from patients exhibiting blast transformation and in vivo xenograft tumors, use of oxythiamine, which can inhibit both the pyruvate dehydrogenase complex and transketolase, resulted in enhanced imatinib sensitivity of tumor cells. Together, these results suggest that oxythiamine can enhance imatinib efficacy in patients who present an accelerated form of the disease.
Subject(s)
Drug Resistance, Neoplasm , Fusion Proteins, bcr-abl/metabolism , Glucose/metabolism , Hypoxia-Inducible Factor 1, alpha Subunit/metabolism , Leukemia, Myelogenous, Chronic, BCR-ABL Positive/metabolism , Piperazines/pharmacology , Protein Kinase Inhibitors/pharmacology , Pyrimidines/pharmacology , Animals , Apoptosis , Benzamides , Blast Crisis , Cell Line, Tumor , Cell Proliferation , Gene Expression Regulation, Neoplastic , Humans , Hypoxia , Hypoxia-Inducible Factor 1, alpha Subunit/antagonists & inhibitors , Hypoxia-Inducible Factor 1, alpha Subunit/genetics , Imatinib Mesylate , Leukemia, Myelogenous, Chronic, BCR-ABL Positive/drug therapy , Leukemia, Myelogenous, Chronic, BCR-ABL Positive/pathology , Male , Mice , Mice, Nude , RNA, Small Interfering/pharmacology , Ribose/metabolism , Up-Regulation , Xenograft Model Antitumor AssaysABSTRACT
Xenotransplantation of human acute myeloid leukemia (AML) in immunocompromised animals has been critical for defining leukemic stem cells. However, existing immunodeficient strains of mice have short life spans and low levels of AML cell engraftment, hindering long-term evaluation of primary human AML biology. A recent study suggested that NOD/LtSz-scid IL2Rgammac null (NSG) mice have enhanced AML cell engraftment, but this relied on technically challenging neonatal injections. Here, we performed extensive analysis of AML engraftment in adult NSG mice using tail vein injection. Of the 35 AML samples analyzed, 66% showed bone marrow engraftment over 0.1%. Further, 37% showed high levels of engraftment (>10%), with some as high as 95%. A 2-44-fold expansion of AML cells was often seen. Secondary and tertiary recipients showed consistent engraftment, with most showing further AML cell expansion. Engraftment did not correlate with French-American-British subtype or cytogenetic abnormalities. However, samples with FLT3 mutations showed a higher probability of engraftment than FLT3 wild type. Importantly, animals developed organomegaly and a wasting illness consistent with advanced leukemia. We conclude that the NSG xenotransplantation model is a robust model for human AML cell engraftment, which will allow better characterization of AML biology and testing of new therapies.
