Subject(s)
Integrin alpha4/metabolism , Precursor Cell Lymphoblastic Leukemia-Lymphoma/drug therapy , Precursor Cell Lymphoblastic Leukemia-Lymphoma/metabolism , Precursor Cells, B-Lymphoid/drug effects , Thiophenes/chemistry , Urea/analogs & derivatives , Animals , Antineoplastic Agents/chemistry , Coculture Techniques , Drug Resistance, Neoplasm , Humans , Inflammation , Leukemia/drug therapy , Mice , Neoplasm Transplantation , Precursor Cells, B-Lymphoid/cytology , Stromal Cells/cytology , Thiophenes/administration & dosage , Urea/administration & dosage , Urea/chemistryABSTRACT
Drug resistance in acute lymphoblastic leukemia (ALL) remains a major problem warranting new treatment strategies. Wnt/catenin signaling is critical for the self-renewal of normal hematopoietic progenitor cells. Deregulated Wnt signaling is evident in chronic and acute myeloid leukemia; however, little is known about ALL. Differential interaction of catenin with either the Kat3 coactivator CREBBP (CREB-binding protein (CBP)) or the highly homologous EP300 (p300) is critical to determine divergent cellular responses and provides a rationale for the regulation of both proliferation and differentiation by the Wnt signaling pathway. Usage of the coactivator CBP by catenin leads to transcriptional activation of cassettes of genes that are involved in maintenance of progenitor cell self-renewal. However, the use of the coactivator p300 leads to activation of genes involved in the initiation of differentiation. ICG-001 is a novel small-molecule modulator of Wnt/catenin signaling, which specifically binds to the N-terminus of CBP and not p300, within amino acids 1-110, thereby disrupting the interaction between CBP and catenin. Here, we report that selective disruption of the CBP/ß- and γ-catenin interactions using ICG-001 leads to differentiation of pre-B ALL cells and loss of self-renewal capacity. Survivin, an inhibitor-of-apoptosis protein, was also downregulated in primary ALL after treatment with ICG-001. Using chromatin immunoprecipitation assay, we demonstrate occupancy of the survivin promoter by CBP that is decreased by ICG-001 in primary ALL. CBP mutations have been recently identified in a significant percentage of ALL patients, however, almost all of the identified mutations reported occur C-terminal to the binding site for ICG-001. Importantly, ICG-001, regardless of CBP mutational status and chromosomal aberration, leads to eradication of drug-resistant primary leukemia in combination with conventional therapy in vitro and significantly prolongs the survival of NOD/SCID mice engrafted with primary ALL. Therefore, specifically inhibiting CBP/catenin transcription represents a novel approach to overcome relapse in ALL.
Subject(s)
Antineoplastic Agents/pharmacology , Bridged Bicyclo Compounds, Heterocyclic/pharmacology , Peptide Fragments/metabolism , Precursor Cell Lymphoblastic Leukemia-Lymphoma/drug therapy , Pyrimidinones/pharmacology , Sialoglycoproteins/metabolism , beta Catenin/metabolism , Animals , Asparaginase/pharmacology , Cell Line, Tumor , Cell Proliferation/drug effects , Cell Survival/drug effects , Dexamethasone/pharmacology , Down-Regulation/drug effects , Drug Resistance, Neoplasm , Drug Synergism , Humans , Inhibitor of Apoptosis Proteins/genetics , Inhibitor of Apoptosis Proteins/metabolism , Mice , Mice, Inbred NOD , Mice, SCID , Mutation , Peptide Fragments/antagonists & inhibitors , Peptide Fragments/genetics , Sialoglycoproteins/antagonists & inhibitors , Sialoglycoproteins/genetics , Survivin , Vincristine/pharmacology , Wnt Signaling Pathway , Xenograft Model Antitumor AssaysABSTRACT
BACKGROUND: Human mesenchymal stem cells (MSC) possess powerful ex vivo expansion and versatile differentiation potential, placing themselves at the forefront of the field of stem cell-based therapy and transplantation. Of high clinical relevance is the endothelial differentiation potential of MSC, which can be used to treat various forms of ischemic vascular disease. METHODS: We investigated whether human umbilical cord blood (UCB)-derived MSC are able to differentiate in vitro along an endothelial lineage, by using flow cytometry, RT-PCR and immunofluorescence analyzes, as well as an Ab array method. RESULTS: When the cells were incubated for up to 3 weeks in the presence of VEGF, EGF and hydrocortisone, they began to express a variety of endothelial lineage surface markers, such as Flk-1, Flt-1, VE-Cadherin, vWF, VCAM-1, Tie-1 and Tie-2, and to secrete a specific set of cytokines. Differentiated cells were also found to be able to uptake low-density lipoprotein and form a tubular network structure. DISCUSSION: These observations have led us to conclude that UCB-derived MSC retain endothelial potential that is suitable for basic and clinical studies aimed at the development of vasculature-directed regenerative medicine.
