title: 3,4-dihydroxyphenylalanine (dopa) metabolism and retinoic acid induced differentiation in human neuroblastoma.
abstract: In mature cells of the sympathetic nervous system and the adrenal gland, the activity of dihydroxyphenylalanine decarboxylase (DDC) is higher than that of tyrosine hydroxylase and 3,4-dihydroxyphenylalanine (dopa) does not accumulate in the cells. On the other hand, it is known that in some neuroblastoma cells there is a relative deficiency of DDC, resulting in accumulation and secretion of dopa. Such a relative deficiency of DDC is a characteristic of neural cells at an early stage of neural crest development, suggesting the neuroblastoma are cells arrested in early neural crest development. If this were the case, it is possible that agents such as retinoic acid (RA) could induce neuroblastoma to differentiate into mature cells with respect to their metabolism of catecholamines. We have measured the effect of RA on the metabolism of dopa and expression of tyrosine hydroxylase and DDC in human neuroblastoma cell lines, CHP-126, CHP-134, IMR-32, NB-69, and LA-N-5. When the cell cultures were treated with RA, they showed wide variations in response as measured by morphological change, growth inhibition, enzyme activities and enzyme expressions. The RA treatment modulated the activities of tyrosine hydroxylase and DDC, but does not increase DDC relative to tyrosine hydroxylase. It is concluded that RA does not induce biochemical differentiation of the neuroblastoma into mature cells even when there are extensive morphological changes and suppression of growth rate.
authors.affiliation: Department of Biochemistry and Biophysics, Medical School, University of Pennsylvania, Philadelphia 19104.
authors.forename: H
authors.initials: H
authors.lastname: Ikeda
authors.forename: A
authors.initials: A
authors.lastname: Pastuszko
authors.forename: N
authors.initials: N
authors.lastname: Ikegaki
authors.forename: R H
authors.initials: RH
authors.lastname: Kennett
authors.forename: D F
authors.initials: DF
authors.lastname: Wilson
mesh_terms: D002454:Cell Differentiation / Q000187:drug effects*; D004295:Dihydroxyphenylalanine / Q000378:metabolism*; D004296:Dopa Decarboxylase / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism; D006801:Humans; D009447:Neuroblastoma / Q000378:metabolism* / Q000473:pathology; D014212:Tretinoin / Q000494:pharmacology*; D014316:Tritium; D014407:Tumor Cells, Cultured; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
chemical_list: D014316:Tritium; D014212:Tretinoin; D004295:Dihydroxyphenylalanine; D014446:Tyrosine 3-Monooxygenase; D004296:Dopa Decarboxylase; D004298:Dopamine