title: Inhibition of IGF1-R overcomes IGFBP7-induced chemotherapy resistance in T-ALL.
abstract: BACKGROUND
  T-cell acute lymphoblastic leukemia (T-ALL) is a genetically heterogeneous disease with the need for treatment optimization. Previously, high expression of Insulin-like growth factor binding protein 7 (IGFBP7), a member of the IGF system, was identified as negative prognostic factor in adult T-ALL patients. Since aberrant IGFBP7 expression was observed in a variety of neoplasia and was relevant for prognosis in T-ALL, we investigated the functional role of IGFBP7 in Jurkat and Molt-4 cells as in vitro models for T-ALL.
  
  
  METHODS
  Jurkat and Molt-4 cells were stably transfected with an IGFBP7 over-expression vector or the empty vector as control. Proliferation of the cells was assessed by WST-1 assays and cell cycle status was measured by flow-cytometry after BrDU/7-AAD staining. The effect of IGFBP7 over-expression on sensitivity to cytostatic drugs was determined in AnnexinV/7-AAD assays. IGF1-R protein expression was measured by Western Blot and flow-cytometric analysis. IGF1-R associated gene expression profiles were generated from microarray gene expression data of 86 T-ALL patients from the Microarrays Innovations in Leukemia (MILE) multicenter study.
  
  
  RESULTS
  IGFBP7-transfected Jurkat cells proliferated less, leading to a longer survival in a nutrient-limited environment. Both IGFBP7-transfected Jurkat and Molt-4 cells showed an arrest in the G0/G1 cell cycle phase. Furthermore, Jurkat IGFBP7-transfected cells were resistant to vincristine and asparaginase treatment. Surface expression and whole protein measurement of IGF1-R protein expression showed a reduced abundance of the receptor after IGFBP7 transfection in Jurkat cells. Interestingly, combination of the IGF1-R inhibitor NPV-AEW541 restored sensitivity to vincristine in IGFBP7-transfected cells. Additionally, IGF1-R associated GEP revealed an up-regulation of important drivers of T-ALL pathogenesis and regulators of chemo-resistance and apoptosis such as NOTCH1, BCL-2, PRKCI, and TP53.
  
  
  CONCLUSIONS
  This study revealed a proliferation inhibiting effect of IGFBP7 by G0/G1 arrest and a drug resistance-inducing effect of IGFBP7 against vincristine and asparaginase in T-ALL. These results provide a model for the previously observed association between high IGFBP7 expression and chemotherapy failure in T-ALL patients. Since the resistance against vincristine was abolished by IGF1-R inhibition, IGFBP7 could serve as biomarker for patients who may benefit from therapies including IGF1-R inhibitors in combination with chemotherapy.
authors.affiliation: Department of Hematology and Oncology, Campus Benjamin Franklin, Charité - Universitätsmedizin Berlin, Hindenburgdamm 30, Berlin, 12203, Germany. isisi@gmx.net.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Bartram
authors.affiliation: Department of Gastroenterology, Infectiology and Rheumatology, Campus Benjamin Franklin, Charité - Universitätsmedizin Berlin, Hindenburgdamm 30, Berlin, 12203, Germany. ulrike.erben@charite.de.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Erben
authors.affiliation: Department of Hematology and Oncology, Campus Benjamin Franklin, Charité - Universitätsmedizin Berlin, Hindenburgdamm 30, Berlin, 12203, Germany. jutta.ortiz-tanchez@charite.de.
authors.forename: Jutta
authors.initials: J
authors.lastname: Ortiz-Tanchez
authors.affiliation: Department of Gastroenterology, Infectiology and Rheumatology, Campus Benjamin Franklin, Charité - Universitätsmedizin Berlin, Hindenburgdamm 30, Berlin, 12203, Germany. Katja.Blunert@charite.de.
authors.forename: Katja
authors.initials: K
authors.lastname: Blunert
authors.affiliation: Department of Hematology and Oncology, Campus Benjamin Franklin, Charité - Universitätsmedizin Berlin, Hindenburgdamm 30, Berlin, 12203, Germany. cornelia.schlee@charite.de.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Schlee
authors.affiliation: Department of Hematology and Oncology, Campus Benjamin Franklin, Charité - Universitätsmedizin Berlin, Hindenburgdamm 30, Berlin, 12203, Germany. martin.neumann@charite.de.
authors.forename: Martin
authors.initials: M
authors.lastname: Neumann
authors.affiliation: Department of Hematology and Oncology, Campus Benjamin Franklin, Charité - Universitätsmedizin Berlin, Hindenburgdamm 30, Berlin, 12203, Germany. SaHee@gmx.de.
authors.forename: Sandra
authors.initials: S
authors.lastname: Heesch
authors.affiliation: Department of Hematology and Oncology, Campus Benjamin Franklin, Charité - Universitätsmedizin Berlin, Hindenburgdamm 30, Berlin, 12203, Germany. claudia.baldus@charite.de.
authors.forename: Claudia D
authors.initials: CD
authors.lastname: Baldus
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D059447:Cell Cycle Checkpoints / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D015870:Gene Expression; D020869:Gene Expression Profiling; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins / Q000235:genetics*; D019169:Jurkat Cells; D054218:Precursor T-Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics* / Q000378:metabolism*; D017526:Receptor, IGF Type 1; D017451:Receptors, Somatomedin / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D059467:Transcriptome
chemical_list: D000970:Antineoplastic Agents; C000597236:IGF1R protein, human; D018969:Insulin-Like Growth Factor Binding Proteins; D017451:Receptors, Somatomedin; C102529:insulin-like growth factor binding protein-related protein 1; D017526:Receptor, IGF Type 1