title: Metabolism of L-arginine through polyamine and nitric oxide synthase pathways in proliferative or differentiated human colon carcinoma cells.
abstract: HT-29 Glc-/+ cells originate from a human colon adenocarcinoma. These cells have been selected in a glucose-free culture medium and switched back in a glucose-containing medium. In this condition, they can spontaneously differentiate after confluency in enterocyte-like cells according to the activity of the brush-border associated hydrolase dipeptidyl peptidase IV. Since L-arginine can generate polyamines which are necessary for cellular proliferation and also differentiation, and nitric oxide with reported anti-proliferative property, the metabolism of this amino acid was examined in proliferative and differentiated isolated HT-29 cells. Proliferative HT-29 cells were characterized by micromolar intracellular concentration of putrescine and millimolar concentration of spermidine and spermine. In these cells, L-arginine is converted to L-ornithine and putrescine and to a minor part to nitric oxide and L-citrulline. Putrescine was taken up by HT-29 cells, leading to the production of a modest amount of spermidine. The diamine was slightly incorporated into cellular proteins and largely released in the incubation medium. The proliferative HT-29 cells take up spermidine and spermine but do not catabolize these polyamines and slightly released spermidine. Differentiation of HT-29 cells is not associated with change in intracellular polyamine content but is paralleled by an almost complete extinction of de novo synthesis of putrescine (due to a dramatic decrease of ornithine decarboxylase activity) and by a reduced release capacity of putrescine. In contrast, putrescine net uptake and incorporation into cellular proteins remained unchanged after differentiation. Furthermore, spermidine and spermine metabolism as well as the circulation of L-arginine in the nitric oxide synthase pathway were also not modified after differentiation. In conclusion, putrescine is the L-arginine-derived molecule, the metabolism of which is specifically and markedly modified when HT-29 cells move from proliferative to differentiated state.
authors.affiliation: Unité d'Ecologie et de Physiologie du Système Digestif. Institut National de la Recherche Agronomique, Jouy-en-Josas, France.
authors.forename: F
authors.initials: F
authors.lastname: Blachier
authors.forename: M
authors.initials: M
authors.lastname: Selamnia
authors.forename: V
authors.initials: V
authors.lastname: Robert
authors.forename: H
authors.initials: H
authors.lastname: M'Rabet-Touil
authors.forename: P H
authors.initials: PH
authors.lastname: Duée
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism*; D001120:Arginine / Q000378:metabolism*; D002454:Cell Differentiation; D002455:Cell Division; D003110:Colonic Neoplasms / Q000378:metabolism*; D018819:Dipeptidyl Peptidase 4 / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism; D006801:Humans; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D009952:Ornithine / Q000378:metabolism; D011073:Polyamines / Q000378:metabolism*; D011700:Putrescine / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D011073:Polyamines; D005973:Glutamine; D001120:Arginine; D009952:Ornithine; D019001:Nitric Oxide Synthase; D018819:Dipeptidyl Peptidase 4; D011700:Putrescine