title: Down-regulation of retinoic acid receptor activity associated with decreased alpha and gamma isoforms expression in F9 embryonal carcinoma cells differentiated by retinoic acid.
abstract: F9 embryonal carcinoma cells differentiate in response to retinoic acid (RA). To investigate the regulation of RA receptors (RARs) expression during this process, cDNA probes specific for the major RAR isoforms were used. In contrast to the level of RAR beta 2 mRNA which was high in cells treated 5 days with RA and below detection in untreated cells, as previously described, the steady state levels of RAR alpha 1, alpha 2, gamma 1, and gamma 2 mRNAs were markedly decreased in the RA-differentiated cells as compared to untreated cells. The down-regulation of the RA-responsive system in differentiated cells was also evident in gel shift assays as a marked decrease in binding capacity to a retinoid acid response element (beta 2RARE), as well as in chloramphenicol acetyltransferase (CAT) assays as a sixfold decrease in RA-mediated transacting activity via this element. The down-regulation of RAR DNA-binding and transacting activity coincided with the burst in tissue plasminogen activator secretion and thus, occurred at the hinge between early and late differentiation. The down-regulation of RA responsiveness may constitute an important event in the transition between early and late differentiation stage in F9 cells.
authors.affiliation: Division of Medical Oncology, Mount Sinai School of Medicine, New York, New York 10029.
authors.forename: D
authors.initials: D
authors.lastname: Lazega
authors.forename: E
authors.initials: E
authors.lastname: Schenker
authors.forename: N
authors.initials: N
authors.lastname: Busso
authors.forename: A
authors.initials: A
authors.lastname: Zelent
authors.forename: A
authors.initials: A
authors.lastname: Chen
authors.forename: S
authors.initials: S
authors.lastname: Waxman
mesh_terms: D000818:Animals; D001483:Base Sequence; D018236:Carcinoma, Embryonal / Q000378:metabolism* / Q000473:pathology; D002454:Cell Differentiation / Q000187:drug effects; D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D015536:Down-Regulation; D007536:Isomerism; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes / Q000235:genetics; D011401:Promoter Regions, Genetic; D018168:Receptors, Retinoic Acid / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D010959:Tissue Plasminogen Activator / Q000378:metabolism; D015533:Transcriptional Activation; D014212:Tretinoin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
chemical_list: D015345:Oligonucleotide Probes; D018168:Receptors, Retinoic Acid; D014212:Tretinoin; D004247:DNA; D015500:Chloramphenicol O-Acetyltransferase; D010959:Tissue Plasminogen Activator