title: Down-regulation of cyclic nucleotide phosphodiesterase PDE1A is the key event of p73 and UHRF1 deregulation in thymoquinone-induced acute lymphoblastic leukemia cell apoptosis.
abstract: Thymoquinone (TQ), the active principle of Nigella sativa black seeds, has anti-proliferative properties on numerous cancer cell types. Others and we have previously reported that TQ acts as agent that triggers cell cycle arrest and apoptosis through either a p53- or p73-dependent pathway. However, the immediate targets recruited upon TQ-induced cytotoxicity have not yet been clearly identified. We therefore asked whether cyclic nucleotide phosphodiesterases (PDEs) could be involved in TQ-triggered pro-apoptotic reactivity; PDEs are regulators of intracellular levels of cyclic nucleotides and therefore can modulate cAMP and cGMP-dependent cell death pathways. Our results showed that TQ specifically repressed PDE1A expression in the acute lymphoblastic leukemia Jurkat cell line. This effect is concomitant with the previously described sequential deregulation of the expression of the tumor suppressor protein p73 and the epigenetic integrator UHRF1 (Ubiquitin-like, PHD Ring Finger 1). Interestingly, RNA-interference knock-down of PDE1A expression as well as decreased PDE1A expression induced growth inhibition of Jurkat cells, cell cycle arrest and apoptosis through an activation of p73 and a repression of UHRF1. Conversely, PDE1A re-expression counteracted the cellular pro-apoptotic effects of TQ in association with a p73 repression and UHRF1 re-expression. Altogether, our results show that TQ induced an initial down-regulation of PDE1A with a subsequent down-regulation of UHRF1 via a p73-dependent mechanism. This study further proposes that PDE1A might be involved in the epigenetic code inheritance by regulating, via p73, the epigenetic integrator UHRF1. Our findings also suggest that a forced inhibition of PDE1A expression might be a new therapeutic strategy for the management of acute lymphoblastic leukemia.
authors.affiliation: CNRS UMR 7213 Laboratoire de Biophotonique et Pharmacologie, Université de Strasbourg, Faculté de Pharmacie, 74 route du Rhin, Illkirch, France.
authors.forename: Abdurazzag
authors.initials: A
authors.lastname: Abusnina
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Alhosin
authors.forename: Thérèse
authors.initials: T
authors.lastname: Keravis
authors.forename: Christian D
authors.initials: CD
authors.lastname: Muller
authors.forename: Guy
authors.initials: G
authors.lastname: Fuhrmann
authors.forename: Christian
authors.initials: C
authors.lastname: Bronner
authors.forename: Claire
authors.initials: C
authors.lastname: Lugnier
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D016227:Benzoquinones / Q000494:pharmacology*; D022762:CCAAT-Enhancer-Binding Proteins / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000378:metabolism; D002460:Cell Line; D054677:Cyclic Nucleotide Phosphodiesterases, Type 1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D015536:Down-Regulation; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D019169:Jurkat Cells; D009687:Nuclear Proteins / Q000378:metabolism*; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000201:enzymology / Q000378:metabolism*; D034622:RNA Interference; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases
chemical_list: D000970:Antineoplastic Agents; D016227:Benzoquinones; D022762:CCAAT-Enhancer-Binding Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D007527:Isoenzymes; D009687:Nuclear Proteins; C000606460:TP73 protein, human; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins; C406364:UHRF1 protein, human; D044767:Ubiquitin-Protein Ligases; D054677:Cyclic Nucleotide Phosphodiesterases, Type 1; C517265:PDE1A protein, human; C003466:thymoquinone