title: Retinoic acid stimulates protein kinase A-associated G proteins during human teratocarcinoma differentiation.
abstract: Retinoic acid (RA) treatment of F9 murine teratocarcinoma (TC) cells reduces the expression of the protein kinase A (PKA)-associated G protein, G alpha i2. The present study reveals interactions between the RA and PKA pathways during differentiation of the multipotent human TC cell line NTERA-2 clone D1 (abbreviated NT2/D1) which differ from prior reports in F9 TC cells. Compared to untreated NT2/D1 cells, differentiated NT2/D1 cells expressed increased levels of G alpha s and G alpha i1,2 proteins as shown by both immunoblot analysis and cholera toxin- and pertussis toxin-induced ADP ribosylation. To further explore cooperation between these pathways during human TC differentiation, we examined the effects of cyclic adenosine monophosphate (cAMP) on RA-responsive genes and of RA treatment on the transcriptional activation of a cAMP response element (CRE). Compared to RA alone, combined treatment with RA and cAMP augmented the expression of the RA nuclear receptor-beta (RAR-beta). Also, transient transfection assays revealed that cAMP and RA cooperated to enhance CRE transcriptional activation. The cAMP-induced enhancement of RA actions in NT2/D1 cells extended to immunophenotypic changes typical of the neuronal differentiation program induced by RA. In contrast to these findings in NT2/D1 cells, prior work in F9 TC cells showed that cAMP inhibits the RA-mediated augmentation of RAR-beta expression and switches the differentiation program from visceral to parietal endoderm. Thus, unlike murine TC cells, in human NT2/D1 cells RA stimulates PKA-associated G proteins and PKA pathway activation enhances RA-mediated TC differentiation.
authors.affiliation: Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY 10021.
authors.forename: J M
authors.initials: JM
authors.lastname: Kurie
authors.forename: J
authors.initials: J
authors.lastname: Allopenna
authors.forename: E
authors.initials: E
authors.lastname: Dmitrovsky
mesh_terms: D002454:Cell Differentiation / Q000187:drug effects; D000242:Cyclic AMP / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004357:Drug Synergism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D018243:Teratocarcinoma / Q000378:metabolism*; D014212:Tretinoin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
chemical_list: D014212:Tretinoin; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D019204:GTP-Binding Proteins