Leukemia-associated fusion proteins. Multiple mechanisms of action to drive cell transformation.
Leukemic cells are defined by two main biological features: arrest of differentiation at a specific stage compatible with continued proliferation, and enhanced resistance to stress. Recent work shows that the leukemia-associated fusion protein PML-RAR can mediate both biological effects targeting independent pathways, through a unifying mechanism. Differentiation block is achieved through transcriptional silencing of genes physiologically regulated by RAR, which are involved in hematopoietic differentiation. In contrast, enhanced resistance to stress is due to the capacity of the fusion protein to cause degradation of the tumor suppressor p53, thus explaining the puzzling observation that mutations of p53 are remarkably rare in acute myeloid leukemias (AMLs). Interestingly, this latter phenomenon depends on expression of wild-type PML, acting as a molecular bridge between p53 and the fusion protein. Strikingly, both effects require a unifying molecular mechanism: aberrant recruitment of histone deacetylases (HDACs). Therefore, the study of this form of leukemia appears also of interest for a better understanding of the action of HDAC inhibitors, potential antitumor drugs that are at the early stages of clinical studies.
Insinga
Alessandra
A
Department of Experimental Oncology, European Institute of Oncology, Via Ripamonti 435, 20141 Milan, Italy.
Pelicci
Pier Giuseppe
PG
Inucci
Saverio
S
D000208:Acute Disease; D000818:Animals; D017209:Apoptosis / Q000235:genetics / Q000502:physiology; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015973:Gene Expression Regulation, Leukemic; D020868:Gene Silencing; D042822:Genomic Instability; D056572:Histone Deacetylase Inhibitors; D006655:Histone Deacetylases / Q000235:genetics / Q000502:physiology; D007951:Leukemia, Myeloid / Q000235:genetics / Q000473:pathology / Q000503:physiopathology*; D051379:Mice; D009154:Mutation; D009363:Neoplasm Proteins / Q000235:genetics / Q000502:physiology; D015514:Oncogene Proteins, Fusion / Q000235:genetics / Q000502:physiology*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000502:physiology
D004791:Enzyme Inhibitors; D056572:Histone Deacetylase Inhibitors; D009363:Neoplasm Proteins; D015514:Oncogene Proteins, Fusion; D016159:Tumor Suppressor Protein p53; C093476:promyelocytic leukemia-retinoic acid receptor alpha fusion oncoprotein; D006655:Histone Deacetylases