Subject(s)
Antineoplastic Agents/therapeutic use , Fusion Proteins, bcr-abl/genetics , Hematopoietic Stem Cell Transplantation , Imatinib Mesylate/therapeutic use , Precursor Cell Lymphoblastic Leukemia-Lymphoma/drug therapy , Precursor Cell Lymphoblastic Leukemia-Lymphoma/genetics , Adolescent , Adult , Aged , Fusion Proteins, bcr-abl/metabolism , Gene Expression , Gene Expression Profiling , Histone-Lysine N-Methyltransferase/genetics , Histone-Lysine N-Methyltransferase/metabolism , Humans , Ikaros Transcription Factor/genetics , Ikaros Transcription Factor/metabolism , Middle Aged , Mutation , Myeloid-Lymphoid Leukemia Protein/genetics , Myeloid-Lymphoid Leukemia Protein/metabolism , Precursor Cell Lymphoblastic Leukemia-Lymphoma/mortality , Precursor Cell Lymphoblastic Leukemia-Lymphoma/pathology , Protein Kinase Inhibitors/therapeutic use , Recurrence , Remission Induction , Survival Analysis , Transplantation, HomologousABSTRACT
This study investigated Polo-like kinase 1, a mitotic regulator often over-expressed in solid tumors and adult hematopoietic malignancies, as a potential new target in the treatment of pediatric acute lymphoblastic leukemia. Polo-like kinase 1 protein and Thr210 phosphorylation levels were higher in pediatric acute lymphoblastic leukemia (n=172) than in normal bone marrow mononuclear cells (n=10) (P<0.0001). High Polo-like kinase 1 protein phosphorylation, but not expression, was associated with a lower probability of event-free survival (P=0.042) and was a borderline significant prognostic factor (P=0.065) in a multivariate analysis including age and initial white blood cell count. Polo-like kinase 1 was necessary for leukemic cell survival, since short hairpin-mediated Polo-like kinase 1 knockdown in acute lymphoblastic leukemia cell lines inhibited cell proliferation by G2/M cell cycle arrest and induced apoptosis through caspase-3 and poly (ADP-ribose) polymerase cleavage. Primary patient cells with a high Polo-like kinase 1 protein expression were sensitive to the Polo-like kinase 1-specific inhibitor NMS-P937 in vitro, whereas cells with a low expression and normal bone marrow cells were resistant. This sensitivity was likely not caused by Polo-like kinase 1 mutations, since only one new mutation (Ser335Arg) was found by 454-sequencing of 38 pediatric acute lymphoblastic leukemia cases. This mutation did not affect Polo-like kinase 1 expression or NMS-P937 sensitivity. Together, these results indicate a pivotal role for Polo-like kinase 1 in pediatric acute lymphoblastic leukemia and show potential for Polo-like kinase 1-inhibiting drugs as an addition to current treatment strategies for cases expressing high Polo-like kinase 1 levels.
Subject(s)
Apoptosis/drug effects , Cell Cycle Proteins/antagonists & inhibitors , Cell Proliferation/drug effects , Precursor Cell Lymphoblastic Leukemia-Lymphoma/enzymology , Protein Serine-Threonine Kinases/antagonists & inhibitors , Proto-Oncogene Proteins/antagonists & inhibitors , Pyrazoles/pharmacology , Quinazolines/pharmacology , Apoptosis/genetics , Cell Cycle Proteins/genetics , Cell Line, Tumor , Child , Cohort Studies , Gene Knockdown Techniques/methods , HEK293 Cells , Humans , Precursor Cell Lymphoblastic Leukemia-Lymphoma/genetics , Protein Serine-Threonine Kinases/genetics , Proto-Oncogene Proteins/genetics , Polo-Like Kinase 1ABSTRACT
Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterised by the development of hamartomas in a variety of organs and tissues. The disease is caused by mutations in either the TSC1 gene on chromosome 9q34, or the TSC2 gene on chromosome 16p13.3. The TSC1 and TSC2 gene products, TSC1 and TSC2, interact to form a protein complex that inhibits signal transduction to the downstream effectors of the target of rapamycin complex 1 (TORC1). Here we investigate TSC1 structure and function by analysing a series of truncated TSC1 proteins. We identify specific regions of the protein that are important for TSC1 stability, localisation, interactions and function.
Subject(s)
Gene Deletion , Protein Multimerization/genetics , Tumor Suppressor Proteins/genetics , Tumor Suppressor Proteins/metabolism , Cells, Cultured , Genomic Instability , Humans , Mutant Proteins/chemistry , Mutant Proteins/metabolism , Mutant Proteins/physiology , Protein Binding/genetics , Protein Interaction Mapping , Protein Stability , Protein Structure, Tertiary/genetics , Protein Structure, Tertiary/physiology , Structure-Activity Relationship , Tuberous Sclerosis Complex 1 Protein , Tuberous Sclerosis Complex 2 Protein , Tumor Suppressor Proteins/chemistryABSTRACT
Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterised by the development of hamartomas in a variety of organs and tissues. The disease is caused by mutations in either the TSC1 gene on chromosome 9q34 or the TSC2 gene on chromosome 16p13.3. The TSC1 and TSC2 gene products, TSC1 and TSC2, interact to form a protein complex that inhibits signal transduction to the downstream effectors of the mammalian target of rapamycin (mTOR). Here we investigate the effects of putative TSC1 missense mutations identified in individuals with signs and/or symptoms of TSC on TSC1-TSC2 complex formation and mTOR signalling. We show that specific amino-acid substitutions close to the N-terminal of TSC1 reduce steady-state levels of TSC1, resulting in the activation of mTOR signalling and leading to the symptoms of TSC.