title: Phosphodiesterase 4 inhibitors augment levels of glucocorticoid receptor in B cell chronic lymphocytic leukemia but not in normal circulating hematopoietic cells.
abstract: Type 4 cyclic AMP (cAMP) phosphodiesterase (PDE4) inhibitors, a class of compounds in clinical development that activate cAMP-mediated signaling by inhibiting cAMP catabolism, offer a feasible means by which to potentiate glucocorticoid-mediated apoptosis in lymphoid malignancies such as B-cell chronic lymphocytic leukemia (B-CLL). In this study, we show that PDE4 inhibitors up-regulate glucocorticoid receptor (GRalpha) transcript levels in B-CLL cells but not T-CLL cells or Sezary cells or normal circulating T cells, B cells, monocytes, or neutrophils. Because GRalpha transcript half-life does not vary in CLL cells treated with the prototypic PDE4 inhibitor rolipram, the 4-fold increase in GRalpha mRNA levels observed within 4 h of rolipram treatment seems to result from an increase in GRalpha transcription. Rolipram treatment increases levels of transcripts derived from the 1A3 promoter to a greater extent than the 1B promoter. Treatment of B-CLL cells with two other PDE4 inhibitors currently in clinical development also augments GR transcript levels and glucocorticoid-mediated apoptosis. Washout studies show that simultaneous treatment with both drug classes irreversibly augments apoptosis over the same time frame that GR up-regulation occurs. Although treatment of B-CLL cells with glucocorticoids reduces basal GRalpha transcript levels in a dose-related manner, cotreatment with rolipram maintained GRalpha transcript levels above baseline. Our results suggest that as a result of their unusual sensitivity to PDE4 inhibitor-mediated up-regulation of GRalpha expression, treatment of B-CLL patients with combined PDE4 inhibitor/glucocorticoid therapy may be of therapeutic benefit in this disease.
authors: Evans Department of Medicine, Section of Hematology and Oncology, Boston Medical Center, Boston, Massachusetts 02118, USA.
authors: John A
authors: JA
authors: Meyers
authors: Josephine
authors: J
authors: Taverna
authors: Jorge
authors: J
authors: Chaves
authors: Anthony
authors: A
authors: Makkinje
authors: Adam
authors: A
authors: Lerner
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors*; D000631:Aminopyridines / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D001549:Benzamides / Q000494:pharmacology; D002264:Carboxylic Acids / Q000494:pharmacology; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D003509:Cyclohexanecarboxylic Acids; D003521:Cyclopropanes / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects; D006413:Hematopoietic System / Q000737:chemistry / Q000166:cytology / Q000187:drug effects*; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000188:drug therapy* / Q000378:metabolism; D009570:Nitriles / Q000494:pharmacology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D011965:Receptors, Glucocorticoid / Q000032:analysis / Q000187:drug effects* / Q000235:genetics; D020889:Rolipram / Q000494:pharmacology
chemical_list: D000631:Aminopyridines; D001549:Benzamides; D002264:Carboxylic Acids; D003509:Cyclohexanecarboxylic Acids; D003521:Cyclopropanes; D009570:Nitriles; D010726:Phosphodiesterase Inhibitors; D011965:Receptors, Glucocorticoid; C411470:glucocorticoid receptor alpha; C424423:Roflumilast; D003907:Dexamethasone; C433247:Cilomilast; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D020889:Rolipram
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