This study addresses the contributions of speci®c retinoid receptors during all-trans-retinoic acid (RA)-mediated dierentiation and growth suppression of human embryonal carcinoma cells. The pleiotropic eects of RA are mediated by retinoic acid receptors (RARs) and retinoid X receptors (RXRs), members of the nuclear receptor family of transcription factors. After RA-treatment the multipotent human embryonal carcinoma cell line NTERA-2 clone D1 (NT2/D1) displays limited proliferative potential, reduced tumorigenicity, and morphologic and immunophenotypic neuronal maturation. RARg over-expression in NT2/D1 cells signals mesenchymal NT2/D1 terminal dierentiation while RARa and RARb do not and RARg overcomes retinoid resistance in an NT2/D1 clone (NT2/D1-R1) having deregulated RARg expression. Since RARg transfectants do not display neuronal maturation, this study sought to identify cooperating retinoid receptors engaged in NT2/D1 dierentiation. Through gain of function experiments, this report highlights RXRb as playing an important role along with RARg in signaling dierentiation of NT2/D1 cells. Stable over-expression of RXRb, but not RXRa or RXRg, was found to signal NT2/D1 growth suppression and to induce a non-neuronal morphology and immunophenotype. Notably, co-transfection of RARg and RXRb resulted in marked growth suppression and for the ®rst time, expression of typical neuronal markers of NT2/D1 dierentiation. To clarify the role of RXRb and RARg in this dierentiation program, a modi®ed transient ®broblast growth factor-4 (FGF4) promoter-enhancer reporter assay that re¯ects eective RA-mediated dierentiation of NT2/D1 cells was employed. Transfection of RARg or RXRb in NT2/D1 cells augments transcriptional repression of the FGF4 reporter and RARg and RXRb co-transfection markedly repressed reporter activity, indicating the combined role of these receptors in RA-induced NT2/D1 dierentiation. Taken together, these ®ndings reveal speci®c retinoid receptors must cooperate to signal terminal growth suppression and maturation of NT2/D1 cells. Since the transcriptional repression of FGF4 is coupled to the eective maturation of human embryonal carcinoma cells, the described co-transfection strategy should prove useful to identify genes with positive or negative eects on the dierentiation program of these tumor cells.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.