title: Implication of retinoic acid receptor gamma in squamous differentiation and response to retinoic acid in head and neck SqCC/Y1 squamous carcinoma cells.
abstract: Nuclear retinoic acid receptors are considered to be the mediators of most of the effects of retinoic acid (RA) on gene expression. To explore the role of RA receptor gamma (RARgamma) in the growth and differentiation of SqCC/Y1 head and neck squamous carcinoma cells, they were transfected with RARgamma sense and antisense expression vectors and stable clones in which RARgamma expression was either increased or blocked were isolated. The growth inhibitory effect of RA in monolayer culture was enhanced in the sense transfectants and decreased in the antisense ones. The ability to form colonies in semisolid medium was abolished by RA in the sense transfectants, while the antisense transfected clones exhibited heterogeneous responses. The expression the squamous differentiation markers cytokeratin K1 transglutaminase type I, and involucrin was increased in the absence of exogenous retinoid in a sense transfected clone and decreased in an antisense transfected clone. RA suppressed squamous differentiation in both types of transfectant. The expression of epidermal growth factor receptor (EGFR) was higher in the antisense and lower in the sense transfectant than in the parental cells and RA decreased EGFR mRNA level in the parental and the sense transfectant but not in the antisense transfectant. In addition activator protein-1 (AP-1) binding activity was decreased by the RA treatment in the sense clones, but not in the antisense ones. These results suggest that RARgamma mediates the effects of RA on the cell growth both in monolayer culture and in semisolid medium possibly through AP-1 suppression.
authors.affiliation: Department of Tumor Biology, The University of Texas MD Anderson Cancer Center, Houston 77030, USA.
authors.forename: N
authors.initials: N
authors.lastname: Oridate
authors.forename: N
authors.initials: N
authors.lastname: Esumi
authors.forename: D
authors.initials: D
authors.lastname: Lotan
authors.forename: W K
authors.initials: WK
authors.lastname: Hing
authors.forename: C
authors.initials: C
authors.lastname: Rochette-Egly
authors.forename: P
authors.initials: P
authors.lastname: Chambon
authors.forename: R
authors.initials: R
authors.lastname: Lotan
mesh_terms: D001483:Base Sequence; D002294:Carcinoma, Squamous Cell / Q000473:pathology*; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002455:Cell Division / Q000187:drug effects; D066246:ErbB Receptors / Q000235:genetics; D006258:Head and Neck Neoplasms / Q000473:pathology*; D006801:Humans; D008969:Molecular Sequence Data; D016376:Oligonucleotides, Antisense / Q000235:genetics; D011485:Protein Binding; D018168:Receptors, Retinoic Acid / Q000235:genetics / Q000502:physiology*; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014162:Transfection; D014212:Tretinoin / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D000097768:Retinoic Acid Receptor gamma
chemical_list: D066246:ErbB Receptors; D016376:Oligonucleotides, Antisense; D018168:Receptors, Retinoic Acid; D018808:Transcription Factor AP-1; D014212:Tretinoin; D000097768:Retinoic Acid Receptor gamma