title: Altered gene expression in busulfan-resistant human myeloid leukemia.
abstract: Busulfan (Bu) resistance is a major obstacle to hematopoietic stem cell transplantation (HSCT) of patients with chronic or acute myelogenous leukemia (CML or AML). We used gene expression analysis to identify cellular factors underlying Bu resistance. Two Bu-resistant leukemia cell lines were established, characterized and analyzed for differentially expressed genes. The CML B5/Bu250(6) cells are 4.5-fold more resistant to Bu than their parental B5 cells. The AML KBM3/Bu250(6) cells are 4.0-fold more Bu-resistant than KBM3 parental cells. Both resistant sublines evade Bu-mediated G2-arrest and apoptosis with altered regulations of CHK2 and CDC2 proteins, constitutively up-regulated anti-apoptotic genes (BCL-X(L), BCL2, BCL2L10, BAG3 and IAP2/BIRC3) and down-regulated pro-apoptotic genes (BIK, BNIP3, and LTBR). Bu-induced apoptosis is partly mediated by activation of caspases; use of the inhibitor Z-VAD-FMK completely abrogated PARP1 cleavage and reduced apoptosis by approximately 50%. Furthermore, Bu resistance in these cells may be attributed in part to up-regulation of HSP90 protein and activation of STAT3. The inhibition of HSP90 with geldanamycin attenuated phosphorylated STAT3 and made B5/Bu250(6) and KBM3/Bu250(6) more Bu-sensitive. The analysis of cells derived from patients classified as either clinically resistant or sensitive to high-dose Bu-based chemotherapy indicated alterations in gene expression that were analogous to those observed in the in vitro model cell lines, confirming the potential clinical relevance of this model for Bu resistance.
authors.affiliation: Department of Stem Cell Transplantation and Cellular Therapy, University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, United States.
authors.forename: Benigno C
authors.initials: BC
authors.lastname: Valdez
authors.forename: David
authors.initials: D
authors.lastname: Murray
authors.forename: Latha
authors.initials: L
authors.lastname: Ramdas
authors.forename: Marcos
authors.initials: M
authors.lastname: de Lima
authors.forename: Roy
authors.initials: R
authors.lastname: Jones
authors.forename: Steven
authors.initials: S
authors.lastname: Kornblau
authors.forename: Daniel
authors.initials: D
authors.lastname: Betancourt
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.forename: Richard E
authors.initials: RE
authors.lastname: Champlin
authors.forename: Borje S
authors.initials: BS
authors.lastname: Andersson
mesh_terms: D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D002066:Busulfan / Q000494:pharmacology*; D020169:Caspases / Q000378:metabolism; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D004789:Enzyme Activation / Q000187:drug effects; D016195:G2 Phase / Q000187:drug effects; D020869:Gene Expression Profiling; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects*; D018841:HSP90 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007951:Leukemia, Myeloid / Q000235:genetics* / Q000473:pathology; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000235:genetics / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D018906:Antineoplastic Agents, Alkylating; D014408:Biomarkers, Tumor; D018841:HSP90 Heat-Shock Proteins; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D020169:Caspases; D002066:Busulfan