Blachier F, Selamnia M, Robert V, M'Rabet-Touil H, Duée P H
Unité d'Ecologie et de Physiologie du Système Digestif. Institut National de la Recherche Agronomique, Jouy-en-Josas, France.
Biochim Biophys Acta. 1995 Sep 21;1268(3):255-62. doi: 10.1016/0167-4889(95)00083-5.
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.
HT-29 Glc-/+细胞源自人结肠腺癌。这些细胞已在无葡萄糖培养基中筛选，并换回含葡萄糖的培养基。在此条件下，汇合后它们可根据刷状缘相关水解酶二肽基肽酶IV的活性自发分化为肠上皮样细胞。由于L-精氨酸可生成细胞增殖和分化所必需的多胺，以及具有抗增殖特性的一氧化氮，因此在增殖的和分化的分离HT-29细胞中研究了这种氨基酸的代谢。增殖的HT-29细胞的特征是细胞内腐胺浓度为微摩尔级，亚精胺和精胺浓度为毫摩尔级。在这些细胞中，L-精氨酸转化为L-鸟氨酸和腐胺，少量转化为一氧化氮和L-瓜氨酸。HT-29细胞摄取腐胺，导致产生少量亚精胺。二胺少量掺入细胞蛋白质中，并大量释放到孵育培养基中。增殖的HT-29细胞摄取亚精胺和精胺，但不分解这些多胺，并少量释放亚精胺。HT-29细胞的分化与细胞内多胺含量的变化无关，但与腐胺从头合成几乎完全消失（由于鸟氨酸脱羧酶活性急剧下降）以及腐胺释放能力降低同时发生。相反，分化后腐胺的净摄取和掺入细胞蛋白质的情况保持不变。此外，分化后亚精胺和精胺的代谢以及一氧化氮合酶途径中L-精氨酸的循环也未改变。总之，腐胺是源自L-精氨酸的分子，当HT-29细胞从增殖状态转变为分化状态时，其代谢会发生特异性和显著改变。
