title: Genomic mechanisms of p210BCR-ABL signaling: induction of heat shock protein 70 through the GATA response element confers resistance to paclitaxel-induced apoptosis.
abstract: Chronic myelogenous leukemia (CML) results from a t(9,22) translocation, producing the p210(BCR-ABL) oncoprotein, a tyrosine kinase that causes transformation and chemotherapy resistance. To further understand mechanisms mediating chemotherapy resistance, we identified 556 differentially regulated genes in HL-60 cells stably expressing p210(BCR-ABL) versus those expressing an empty vector using cDNA macro- and oligonucleotide microarrays. These BCR-ABL-regulated gene products play diverse roles in cellular function including apoptosis, cell cycle regulation, intracellular signaling, transcription, and cellular adhesion. In particular, we identified up-regulation of the inducible form of heat shock protein 70 (Hsp70), and further explored the mechanism for its up-regulation. In HL-60/BCR-ABL and K562 cells (expressing p210(BCR-ABL)), abundant cytoplasmic Hsp70 expression was detected by immunoblot analysis. Moreover, cells isolated from bone marrow aspirates of patients in different stages of CML (chronic, aggressive, and blast crisis) express Hsp70. Expression of p210(BCR-ABL) in BCR-ABL negative cells induced transcription of the proximal Hsp70 promoter. Mutational analysis mapped the major p210(BCR-ABL) responsive element to a high affinity 5'(A/T)GATA(A/G)-3' "GATA" response element (GATA-RE) that binds GATA-1 in CML cells. The GATA-RE was sufficient to confer p210(BCR-ABL)- and p185(BCR-ABL)-mediated trans-activation to an inert promoter. Short interfering RNA mediated "knockdown" of Hsp70 expression in K562 cells induced marked sensitivity to paclitaxel-induced apoptosis. Together these findings indicate that BCR-ABL confers chemotherapeutic resistance through intracellular signaling to the GATA-RE element found in the promoter region of the anti-apoptotic Hsp70 protein. We suggest that down-regulation of the GATA-Hsp70 pathway may be useful in the treatment of chemotherapy-resistant CML.
authors.affiliation: Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas 77555-1060, USA.
authors.forename: Sutapa
authors.initials: S
authors.lastname: Ray
authors.forename: Ying
authors.initials: Y
authors.lastname: Lu
authors.forename: Scott H
authors.initials: SH
authors.lastname: Kaufmann
authors.forename: W Clay
authors.initials: WC
authors.lastname: Gustafson
authors.forename: Judith E
authors.initials: JE
authors.lastname: Karp
authors.forename: Istvan
authors.initials: I
authors.lastname: Boldogh
authors.forename: Alan P
authors.initials: AP
authors.lastname: Fields
authors.forename: Allan R
authors.initials: AR
authors.lastname: Brasier
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D004268:DNA-Binding Proteins; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D050981:Erythroid-Specific DNA-Binding Factors; D016044:Fusion Proteins, bcr-abl / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D050982:GATA1 Transcription Factor; D015894:Genome, Human; D018922:HL-60 Cells; D018840:HSP70 Heat-Shock Proteins / Q000502:physiology*; D006801:Humans; D020014:K562 Cells; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000188:drug therapy / Q000235:genetics*; D017239:Paclitaxel / Q000494:pharmacology*; D011401:Promoter Regions, Genetic; D020218:Response Elements / Q000502:physiology; D014157:Transcription Factors
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D050982:GATA1 Transcription Factor; C494688:GATA1 protein, human; D018840:HSP70 Heat-Shock Proteins; D014157:Transcription Factors; D016044:Fusion Proteins, bcr-abl; D017239:Paclitaxel