title: Common defects of different retinoic acid resistant promyelocytic leukemia cells are persistent telomerase activity and nuclear body disorganization.
abstract: The acute promyelocytic leukemia (APL) t(15;17) rearrangement fuses the promyelocytic leukemia (PML) gene to the retinoic acid receptor-alpha (RAR alpha). There is expression of the chimeric transcript, PML/RAR alpha, in these APL cells. These clinical APL cases respond to the differentiation agent all-trans retinoic acid (ATRA) with complete but not durable remissions because ATRA resistance develops. The NB4 APL cell line expresses PML/RAR alpha and responds to the growth inhibitory and differentiation-inducing signals of ATRA. To identify mechanisms responsible for ATRA resistance in APL, ATRA-resistant NB4 cell lines were derived from parental NB4 cells using different strategies. These lines were resistant to the growth inhibition and differentiation effects of ATRA. ATRA-resistant cells were isolated as a de novo resistant line from parental NB4 cells (NB4-R1), following chemical mutagenization and selection in ATRA (NB4-R2), or after chronic selection in ATRA (NB4-R3). Common defects linked to this ATRA resistance were found. When cultured in ATRA, these resistant cells still express PML, RAR alpha, and PML/RAR alpha proteins. Sequence abnormalities were not detected in the RAR alpha DNA binding domains cloned from a representative RA-resistant NB4 line. In ATRA-sensitive but not ATRA-resistant NB4 cells, ATRA down-regulated retinoid X receptor-alpha (RXR alpha) expression, a known marker of ATRA response in parental NB4 cells. Notably, engineered overexpression of RXR alpha in ATRA-sensitive NB4 cells did not block ATRA-mediated growth suppression. ATRA treatment of these resistant NB4 lines did not signal a decline in telomerase activity or reorganization of PML-associated nuclear bodies, but both events occurred in ATRA-sensitive NB4 cells. These ATRA-resistant NB4 lines are not fully differentiation-defective, since monocytic maturation was induced following treatment with phorbol 12-myristate 13-acetate (PMA) and 1,25 dihydroxy vitamin D3 (vitamin D3). Notably, induced monocytic differentiation of these distinct ATRA-resistant APL lines markedly repressed telomerase activity. Thus, this study suggests that persistent telomerase activity and nuclear body disorganization are linked to ATRA resistance in APL.
authors.affiliation: Laboratory of Molecular Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA.
authors.forename: K
authors.initials: K
authors.lastname: Nason-Burchenal
authors.forename: W
authors.initials: W
authors.lastname: Maerz
authors.forename: J
authors.initials: J
authors.lastname: Albanell
authors.forename: J
authors.initials: J
authors.lastname: Allopenna
authors.forename: P
authors.initials: P
authors.lastname: Martin
authors.forename: M A
authors.initials: MA
authors.lastname: Moore
authors.forename: E
authors.initials: E
authors.lastname: Dmitrovsky
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D001665:Binding Sites; D015153:Blotting, Western; D002273:Carcinogens; D002454:Cell Differentiation / Q000502:physiology; D002455:Cell Division / Q000187:drug effects; D002467:Cell Nucleus / Q000648:ultrastructure; D002762:Cholecalciferol / Q000494:pharmacology; D002999:Clone Cells; D004273:DNA, Neoplasm / Q000378:metabolism; D019008:Drug Resistance, Neoplasm; D006801:Humans; D015473:Leukemia, Promyelocytic, Acute / Q000188:drug therapy / Q000201:enzymology* / Q000473:pathology*; D008769:Methylnitronitrosoguanidine; D016133:Polymerase Chain Reaction; D018168:Receptors, Retinoic Acid / Q000096:biosynthesis; D000072482:Retinoic Acid Receptor alpha; D019098:Telomerase / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic; D014212:Tretinoin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D002273:Carcinogens; D004273:DNA, Neoplasm; C000607071:RARA protein, human; D018168:Receptors, Retinoic Acid; D000072482:Retinoic Acid Receptor alpha; D008769:Methylnitronitrosoguanidine; D002762:Cholecalciferol; D014212:Tretinoin; D019098:Telomerase; D013755:Tetradecanoylphorbol Acetate