title: Effect of retinoic acid on p21ras and regulators of its activity in neuroblastoma.
abstract: p21ras is a membrane-associated guanine nucleotide-binding protein with intrinsic GTPase activity. This protein is important in the regulation of cell growth and differentiation in a number of different cell types. Therefore, the aim of the present study was to examine the role of p21ras and regulators of its activity in the differentiation of neuroblastoma cells induced by retinoic acid (RA). Phosphorylation of p21ras is regulated by the GTPase activity of type I GAP120 and neurofibromin. RA-induced differentiation of the two neuroblastoma cell lines SK-N-SH and IMR-32 was closely related to growth inhibition. Differentiation induced by RA resulted in an increase in both type I GAP120 and neurofibromin mRNAs. This increase was accompanied by a decrease in the activation of p21ras. These results suggest that, in neuroblastoma, activation of p21ras is not associated with RA-induced differentiation. However, the GTPase activating proteins type I GAP120 and neurofibromin may have effector functions in RA-induced differentiation of neuroblastoma.
authors.affiliation: Candlelighter's Children's Research Laboratory Imperial Cancer Research Fund, St James' University Hospital, Leeds, U.K.
authors.forename: S A
authors.initials: SA
authors.lastname: Burchill
authors.forename: P A
authors.initials: PA
authors.lastname: Berry
authors.forename: I J
authors.initials: IJ
authors.lastname: Lewis
mesh_terms: D001483:Base Sequence; D015153:Blotting, Western; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D020690:GTPase-Activating Proteins; D006801:Humans; D007641:Keratolytic Agents / Q000494:pharmacology*; D008969:Molecular Sequence Data; D009447:Neuroblastoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D025542:Neurofibromin 1; D016133:Polymerase Chain Reaction; D011506:Proteins / Q000187:drug effects* / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000187:drug effects* / Q000378:metabolism; D014212:Tretinoin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured / Q000187:drug effects; D020703:ras GTPase-Activating Proteins
chemical_list: D020690:GTPase-Activating Proteins; D007641:Keratolytic Agents; D025542:Neurofibromin 1; D011506:Proteins; D016760:Proto-Oncogene Proteins c-fos; D020703:ras GTPase-Activating Proteins; D014212:Tretinoin; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)