title: mRNA expression levels of (co)chaperone molecules of the glucocorticoid receptor are not involved in glucocorticoid resistance in pediatric ALL.
abstract: Resistance to glucocorticoids (GC) is an important adverse risk factor in the treatment of acute lymphoblastic leukemia (ALL). To induce apoptosis, GC bind to the GC receptor (GR), which is regulated by various (co)chaperone proteins such as heat-shock protein 70 (HSP-70), HSP-40, HIP (HSP-70-interacting protein), BAG-1 (BCL-2-associated gene product-1), HOP (HSP-70/HSP-90-Organizing protein), HSP-90, P-23, FKBP-51, FKBP-52 and CYP-40. In this study, we tested the hypothesis that mRNA expression levels of these molecules are determinants of GC resistance in childhood ALL. In all, 20 children with ALL cells in vitro sensitive to prednisolone (LC(50) < 0.1 microg/ml) were compared each with a resistant patient (LC(50) >150 mug/ml), matched for immunophenotype, age and white blood cell count. mRNA expression levels of the (co)chaperone molecules were measured by quantitative real-time RT-PCR and normalized to GAPDH and RNaseP levels. In vitro resistance to prednisolone was measured by MTT assay. HSP-90 mRNA expression levels were 2000-fold higher as compared to HSP-70. Using matched pair analysis, mRNA expression levels of the various (co)chaperone molecules were not significantly different between in vitro-sensitive and -resistant patients. GC resistance in childhood ALL cannot be attributed to different mRNA expression levels of the investigated (co)chaperone molecules involved in GC binding and transport to the nucleus.
authors.affiliation: Division of Pediatric Oncology/Hematology, Erasmus MC-Sophia Childrens Hospital, University Medical Center Rotterdam, The Netherlands.
authors.forename: W J E
authors.initials: WJ
authors.lastname: Tissing
authors.forename: J P P
authors.initials: JP
authors.lastname: Meijerink
authors.forename: M L
authors.initials: ML
authors.lastname: den Boer
authors.forename: B
authors.initials: B
authors.lastname: Brinkhof
authors.forename: R
authors.initials: R
authors.lastname: Pieters
mesh_terms: D016022:Case-Control Studies; D002470:Cell Survival / Q000187:drug effects; D002648:Child; D002675:Child, Preschool; D019008:Drug Resistance, Neoplasm; D004354:Drug Screening Assays, Antitumor / Q000379:methods; D005938:Glucocorticoids / Q000378:metabolism / Q000494:pharmacology*; D018840:HSP70 Heat-Shock Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D018841:HSP90 Heat-Shock Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007223:Infant; D018832:Molecular Chaperones / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000188:drug therapy* / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D021381:Protein Transport / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D011965:Receptors, Glucocorticoid / Q000187:drug effects / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012307:Risk Factors; D012680:Sensitivity and Specificity
chemical_list: D005938:Glucocorticoids; D018840:HSP70 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins; D018832:Molecular Chaperones; D012333:RNA, Messenger; D011965:Receptors, Glucocorticoid