Daly P F, Zugmaier G, Sandler D, Carpen M, Myers C E, Cohen J S
Pediatric Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892.
Cancer Res. 1990 Feb 1;50(3):552-7.
Using 31P nuclear magnetic resonance spectroscopy we have noninvasively observed metabolic control through the cytidine pathways of phosphatidylcholine and phosphatidylethanolamine synthesis in intact actively metabolizing MDA-MB-231 human breast cancer cells. Perfusion with the phospholipid precursors ethanolamine or choline (2 mM) indicates that the cytidylyltransferase enzymes are rate limiting for both pathways. Complete inhibition of choline kinase with ethanolamine allowed the observation of the utilization of phosphocholine by the rate-limiting enzyme choline-phosphate cytidylyltransferase. The rate was dependent on the phosphocholine concentration. Inhibition of glycerophosphorylcholine phosphodiesterase with accumulation of substrate was also observed and allows an estimate of the flux through the degradative pathways. The human lymphoma cell line MOLT-4 was also found to contain high levels of phosphocholine and phosphoethanolamine. The levels of these precursors in the MOLT-4 line are lowered by 40% after 6 h when perfused with high dose 1-beta-D-arabinofuranosylcytosine (Ara-C) (400 microns) but are unaffected by 2 microns Ara-C or dideoxycytidine. High dose Ara-C also resulted in lysis in 8-10 h. However, the MDA-MB-231 cell line which is not sensitive to Ara-C showed no change in its spectrum when perfused with Ara-C. A potential mechanism based on classic phospholipid metabolism for the lytic effect of high dose Ara-C is discussed.
利用31P核磁共振波谱技术，我们在完整的、活跃代谢的MDA - MB - 231人乳腺癌细胞中，通过磷脂酰胆碱和磷脂酰乙醇胺合成的胞苷途径，对代谢控制进行了非侵入性观察。用磷脂前体乙醇胺或胆碱（2 mM）灌注表明，胞苷酰转移酶对这两条途径均具有限速作用。用乙醇胺完全抑制胆碱激酶后，可观察到限速酶胆碱磷酸胞苷酰转移酶对磷酸胆碱的利用情况。其速率取决于磷酸胆碱的浓度。还观察到甘油磷酸胆碱磷酸二酯酶被抑制且底物积累，这使得我们能够估计通过降解途径的通量。人类淋巴瘤细胞系MOLT - 4也被发现含有高水平的磷酸胆碱和磷酸乙醇胺。当用高剂量的1 - β - D - 阿拉伯呋喃糖基胞嘧啶（Ara - C）（400 μM）灌注6小时后，MOLT - 4细胞系中这些前体的水平降低了40%，但不受2 μM Ara - C或双脱氧胞苷的影响。高剂量的Ara - C在8 - 10小时内也导致细胞裂解。然而，对Ara - C不敏感的MDA - MB - 231细胞系在用Ara - C灌注时其光谱没有变化。本文讨论了基于经典磷脂代谢的高剂量Ara - C裂解作用的潜在机制。
