title: Proteomics-based strategy to identify biomarkers and pharmacological targets in leukemias with t(4;11) translocations.
abstract: Translocations and other aberrations involving the MLL (mixed lineage leukemia) gene result in aggressive forms of leukemias. Heterogeneity in partner genes, in chromosomal breakpoints, in MLL itself, and in the different partner genes results in heterogeneous fusion transcripts that can be alternatively spliced, which complicates deciphering a unifying mechanism of leukemogenesis. However, recent microarray studies completed with clinical leukemia specimens have uncovered several distinct mRNA signatures within MLL leukemia that differ from other types of leukemia. A global proteomics strategy using MV4-11 and RS4:11 cells in culture was employed to investigate possible protein signatures common to different MLL leukemias and to identify disease biomarkers and protein targets for pharmacological intervention. Initial proteomics screening experiments with two-dimensional differential in-gel electrophoresis revealed heat shock protein 90 alpha (HSP90alpha) as a potential target for pharmacological inhibition and nucleoside diphosphate kinase (nm23) as a biomarker for measuring treatment efficacy. Using a modified stable isotope labeling of amino acids in cell culture (SILAC) approach, coupled with two-dimensional liquid chromatography tandem mass spectrometry (2D-LC-MS/MS), changes in abundance for over 500 proteins were measured. In addition, decreased expression of the novel biomarker nm23 was observed during HSP90 inhibition with 17-allylamino-17-demethoxygeldanamycin (17-AAG) in the MV4-11 cell line. The present study validates the use of a global proteomics strategy to uncover novel biomarkers and pharmacological targets for leukemias with MLL translocations. Additionally, several proteins were found to be expressed in concordance with microarray studies of mRNA expression in specimens from patients showing the value in comparing mRNA transcript and proteomic profiles. This work represents one of the most comprehensive proteomics screens of MLL leukemias that have been conducted to date.
authors.affiliation: Center for Cancer Pharmacology, University of Pennsylvania School of Medicine, and Division of Oncology, The Children's Hospital of Philadelphia, Department of Pediatrics, Pennsylvania 19104-4318, USA.
authors.forename: Anastasia K
authors.initials: AK
authors.lastname: Yocum
authors.forename: Christine M
authors.initials: CM
authors.lastname: Busch
authors.forename: Carolyn A
authors.initials: CA
authors.lastname: Felix
authors.forename: Ian A
authors.initials: IA
authors.lastname: Blair
mesh_terms: D000595:Amino Acid Sequence; D016227:Benzoquinones / Q000494:pharmacology / Q000627:therapeutic use; D014408:Biomarkers, Tumor / Q000032:analysis* / Q000235:genetics; D002880:Chromosomes, Human, Pair 11 / Q000235:genetics; D002894:Chromosomes, Human, Pair 4 / Q000235:genetics; D015180:Electrophoresis, Gel, Two-Dimensional; D018841:HSP90 Heat-Shock Proteins / Q000032:analysis*; D006801:Humans; D047029:Lactams, Macrocyclic / Q000494:pharmacology / Q000627:therapeutic use; D007938:Leukemia / Q000175:diagnosis* / Q000188:drug therapy / Q000235:genetics*; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D051788:Myeloid-Lymphoid Leukemia Protein / Q000235:genetics*; D009363:Neoplasm Proteins / Q000032:analysis* / Q000235:genetics; D009701:Nucleoside-Diphosphate Kinase / Q000032:analysis; D020543:Proteome / Q000032:analysis* / Q000235:genetics; D040901:Proteomics / Q000379:methods; D014178:Translocation, Genetic; D014407:Tumor Cells, Cultured
chemical_list: D016227:Benzoquinones; D014408:Biomarkers, Tumor; D018841:HSP90 Heat-Shock Proteins; D047029:Lactams, Macrocyclic; D009363:Neoplasm Proteins; D020543:Proteome; D051788:Myeloid-Lymphoid Leukemia Protein; C112765:tanespimycin; D009701:Nucleoside-Diphosphate Kinase