The importance of free fatty acid in tumor nutrition.
The importance of free fatty acid in tumor nutrition.
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作者：
A. Spector
在埃利希腹水瘤的腹水中发现了游离脂肪酸，约3%的总脂肪酸以未酯化的形式存在于腹水中。腹水游离脂肪酸组分的主要成分棕榈酸、硬脂酸、油酸和亚油酸也是肿瘤细胞中所含脂肪酸的主要种类。棕榈酸和油酸的示踪实验表明，从40至50%的腹水中的游离脂肪酸流量由肿瘤细胞的摄取。细胞摄取的大部分游离脂肪酸被掺入脂质酯中。相比之下，从肿瘤细胞脂质中回收的腹膜内给药葡萄糖放射性不到1%，皂化后94%掺入脂质的葡萄糖放射性存在于水溶性物质中。吸收的一小部分放射性游离脂肪酸转化为细胞的水溶性成分。使用棕榈酸作为同位素示踪剂，对腹水中所含游离脂肪酸的利用率进行了估计。虽然注意到大的变化，计算的游离脂肪酸周转率的值表明，这种底物可以提供这些肿瘤细胞在体内所需的脂肪酸的大部分。提示埃利希腹水瘤细胞所需的大部分脂肪酸是由宿主预先提供的，其中大部分以游离脂肪酸的形式循环到肿瘤中。
Summary Free fatty acid was found in the ascites fluid of the Ehrlich ascites tumor, about 3% of the total fatty acid contained in the fluid being in unesterified form. The major components of the ascites free fatty acid fraction—palmitate, stearate, oleate, and linoleate—also were the main species of fatty acid contained in the tumor cells. Tracer experiments with palmitate and oleate indicated that from 40 to 50% of the free fatty acid flux in the ascites fluid resulted from uptake by the tumor cells. Most of the free fatty acid taken up by the cells was incorporated into lipid esters. In contrast, less than 1% of the glucose radioactivity administered intraperitoneally was recovered from tumor cell lipid, and 94% of that incorporated into lipid was in watersoluble material following saponification. A small fraction of the radioactive free fatty acid taken up was converted to watersoluble components of the cells. Estimates of the rate of utilization of the free fatty acid contained in the ascites fluid were made using palmitate as the isotopic tracer. Although large variations were noted, the values calculated for the free fatty acid turnover rate indicate that this substrate can provide a large fraction of the fatty acid required by these tumor cells in vivo. It is suggested that much of the fatty acid required by the Ehrlich ascites tumor cell is supplied preformed by the host and that most of this is circulated to the tumor as free fatty acid.