title: PML-RARA-RXR oligomers mediate retinoid and rexinoid/cAMP cross-talk in acute promyelocytic leukemia cell differentiation.
abstract: PML-RARA was proposed to initiate acute promyelocytic leukemia (APL) through PML-RARA homodimer-triggered repression. Here, we examined the nature of the PML-RARA protein complex and of its DNA targets in APL cells. Using a selection/amplification approach, we demonstrate that PML-RARA targets consist of two AGGTCA elements in an astonishing variety of orientations and spacings, pointing to highly relaxed structural constrains for DNA binding and identifying a major gain of function of this oncogene. PML-RARA-specific response elements were identified, which all conveyed a major transcriptional response to RA only in APL cells. In these cells, we demonstrate that PML-RARA oligomers are complexed to RXR. Directly probing PML-RARA function in APL cells, we found that the differentiation enhancer cyclic AMP (cAMP) boosted transcriptional activation by RA. cAMP also reversed the normal silencing (subordination) of the transactivating function of RXR when bound to RARA or PML-RARA, demonstrating that the alternate rexinoid/cAMP-triggered APL differentiation pathway also activates PML-RARA targets. Finally, cAMP restored both RA-triggered differentiation and PML-RARA transcriptional activation in mutant RA-resistant APL cells. Collectively, our findings directly demonstrate that APL cell differentiation parallels transcriptional activation through PML-RARA-RXR oligomers and that those are functionally targeted by cAMP, identifying this agent as another oncogene-targeted therapy.
authors.affiliation: CNRS UPR9051, Hôpital St. Louis, Laboratoire associé N degrees 11, 1, Av. C. Vellefaux, 75475 Paris, Cedex 10, France. email: dethe@chu-st-louis.fr
authors.forename: Dmitrii
authors.initials: D
authors.lastname: Kamashev
authors.forename: Dominique
authors.initials: D
authors.lastname: Vitoux
authors.forename: Hugues
authors.initials: H
authors.lastname: De Thé
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D019556:COS Cells; D002454:Cell Differentiation; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism*; D004273:DNA, Neoplasm / Q000235:genetics / Q000378:metabolism; D006801:Humans; D015473:Leukemia, Promyelocytic, Acute / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D009363:Neoplasm Proteins / Q000737:chemistry / Q000378:metabolism*; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism*; D000071156:Promyelocytic Leukemia Protein; D020239:Receptor Cross-Talk; D018168:Receptors, Retinoic Acid / Q000737:chemistry / Q000378:metabolism*; D000072482:Retinoic Acid Receptor alpha; D047488:Retinoid X Receptors; D012176:Retinoids / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D015533:Transcriptional Activation; D025521:Tumor Suppressor Proteins; D020298:U937 Cells
chemical_list: D004273:DNA, Neoplasm; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D000071156:Promyelocytic Leukemia Protein; C000607071:RARA protein, human; D018168:Receptors, Retinoic Acid; D000072482:Retinoic Acid Receptor alpha; D047488:Retinoid X Receptors; D012176:Retinoids; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; C070576:PML protein, human; D000242:Cyclic AMP