title: Association of high-level MCL-1 expression with in vitro and in vivo prednisone resistance in MLL-rearranged infant acute lymphoblastic leukemia.
abstract: MLL-rearranged acute lymphoblastic leukemia (ALL) represents an unfavorable type of leukemia that often is highly resistant to glucocorticoids such as prednisone and dexamethasone. Because response to prednisone largely determines clinical outcome of pediatric patients with ALL, overcoming resistance to this drug may be an important step toward improving prognosis. Here, we show how gene expression profiling identifies high-level MCL-1 expression to be associated with prednisolone resistance in MLL-rearranged infant ALL, as well as in more favorable types of childhood ALL. To validate this observation, we determined MCL-1 expression with quantitative reverse transcription-polymerase chain reaction in a cohort of MLL-rearranged infant ALL and pediatric noninfant ALL samples and confirmed that high-level MCL-1 expression is associated with prednisolone resistance in vitro. In addition, MCL-1 expression appeared to be significantly higher in MLL-rearranged infant patients who showed a poor response to prednisone in vivo compared with prednisone good responders. Finally, down-regulation of MCL-1 in prednisolone-resistant MLL-rearranged leukemia cells by RNA interference, to some extent, led to prednisolone sensitization. Collectively, our findings suggest a potential role for MCL-1 in glucocorticoid resistance in MLL-rearranged infant ALL, but at the same time strongly imply that high-level MCL-1 expression is not the sole mechanism providing resistance to these drugs.
authors: Department of Pediatric Oncology/Hematology, Erasmus Medical Center-Sophia Children's Hospital, Rotterdam, The Netherlands. r.stam@erasmusmc.nl
authors: Ronald W
authors: RW
authors: Stam
authors: Monique L
authors: ML
authors: Den Boer
authors: Pauline
authors: P
authors: Schneider
authors: Jasper
authors: J
authors: de Boer
authors: Jill
authors: J
authors: Hagelstein
authors: Maria G
authors: MG
authors: Valsecchi
authors: Paola
authors: P
authors: de Lorenzo
authors: Stephen E
authors: SE
authors: Sallan
authors: Hugh J M
authors: HJ
authors: Brady
authors: Scott A
authors: SA
authors: Armstrong
authors: Rob
authors: R
authors: Pieters
mesh_terms: D002470:Cell Survival / Q000187:drug effects; D002648:Child; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D020869:Gene Expression Profiling; D015973:Gene Expression Regulation, Leukemic; D015321:Gene Rearrangement; D005938:Glucocorticoids / Q000494:pharmacology / Q000627:therapeutic use; D011495:Histone-Lysine N-Methyltransferase; D006801:Humans; D015151:Immunoblotting; D007223:Infant; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D051788:Myeloid-Lymphoid Leukemia Protein / Q000235:genetics* / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D011241:Prednisone / Q000494:pharmacology* / Q000627:therapeutic use; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics* / Q000378:metabolism; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D005938:Glucocorticoids; C497422:KMT2A protein, human; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D019253:Proto-Oncogene Proteins c-bcl-2; D051788:Myeloid-Lymphoid Leukemia Protein; D011495:Histone-Lysine N-Methyltransferase; D011241:Prednisone