title: Reduced retinoic acid-sensitivities of nuclear receptor corepressor binding to PML- and PLZF-RARalpha underlie molecular pathogenesis and treatment of acute promyelocytic leukemia.
abstract: Typical acute promyelocytic leukemia (APL) is associated with expression of the PML-RARalpha fusion protein and responsiveness to treatment with all-trans retinoic acid (ATRA). A rare, but recurrent, APL has been described that does not respond to ATRA treatment and is associated with a variant chromosomal translocation and expression of the PLZF-RARalpha fusion protein. Both PML- and PLZF-RARalpha possess identical RAR sequences and inhibit ATRA-induced gene transcription as well as cell differentiation. We now show that the above-mentioned oncogenic fusion proteins interact with the nuclear receptor corepressor N-CoR and, in comparison with the wild-type RARalpha protein, their interactions display reduced sensitivities to ATRA. Although pharmacologic concentration of ATRA could still induce dissociation of N-CoR from PML-RARalpha, it had a very little effect on its association with the PLZF-RARalpha fusion protein. This ATRA-insensitive interaction between N-CoR and PLZF-RARalpha was mediated by the N-terminal PLZF moiety of the chimera. It appears that N-CoR/histone deacetylase corepressor complex interacts directly in an ATRA-insensitive manner with the BTB/POZ-domain of the wild-type PLZF protein and is required, at least in part, for its function as a transcriptional repressor. As the above-noted results predict, histone deacetylase inhibitors antagonize oncogenic activities of the PML-RARalpha fusion protein and partially relieve transcriptional repression by PLZF as well as inhibitory effect of PLZF-RARalpha on ATRA response. Taken together, our results demonstrate involvement of nuclear receptor corepressor/histone deacetylase complex in the molecular pathogenesis of APL and provide an explanation for differential sensitivities of PML- and PLZF-RARalpha-associated leukemias to ATRA.
authors.affiliation: Leukaemia Research Fund Centre at the Institute of Cancer Research, Chester Beatty Laboratories, London, UK.
authors.forename: F
authors.initials: F
authors.lastname: Guidez
authors.forename: S
authors.initials: S
authors.lastname: Ivins
authors.forename: J
authors.initials: J
authors.lastname: Zhu
authors.forename: M
authors.initials: M
authors.lastname: Söderström
authors.forename: S
authors.initials: S
authors.lastname: Waxman
authors.forename: A
authors.initials: A
authors.lastname: Zelent
mesh_terms: D002884:Chromosomes, Human, Pair 15; D002886:Chromosomes, Human, Pair 17; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D051741:Kruppel-Like Transcription Factors; D015473:Leukemia, Promyelocytic, Acute / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D056971:Nuclear Receptor Co-Repressor 1; D015514:Oncogene Proteins, Fusion / Q000235:genetics / Q000378:metabolism*; D000075722:Promyelocytic Leukemia Zinc Finger Protein; D011485:Protein Binding; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014178:Translocation, Genetic; D014212:Tretinoin / Q000494:pharmacology* / Q000627:therapeutic use; D014407:Tumor Cells, Cultured; D016335:Zinc Fingers
chemical_list: D004268:DNA-Binding Proteins; D051741:Kruppel-Like Transcription Factors; C539127:NCOR1 protein, human; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D056971:Nuclear Receptor Co-Repressor 1; D015514:Oncogene Proteins, Fusion; D000075722:Promyelocytic Leukemia Zinc Finger Protein; D012097:Repressor Proteins; D014157:Transcription Factors; C093476:promyelocytic leukemia-retinoic acid receptor alpha fusion oncoprotein; C092037:ZBTB16 protein, human; D014212:Tretinoin