Buhlmann C, Börchers T, Pollak M, Spener F
Department of Biochemistry, University of Münster, Germany.
Mol Cell Biochem. 1999 Sep;199(1-2):41-8. doi: 10.1023/a:1006986629206.
The human breast cancer cell line MCF7 does not express heart-type fatty acid binding protein (H-FABP), a marker protein for differentiated mammary gland. MCF7 cells transfected with the bovine H-FABP cDNA expressed the corresponding protein and were characterized by growth inhibition and lower tumorgenicity in nude mice [22]. By enzyme linked immunoassay we now determined the amount of bovine H-FABP in these cells as 638 +/- 80 ng/mg protein and used the transfected cells to study the role of H-FABP in fatty acid metabolism. Compared to control cells the uptake of radioactively labelled palmitic acid and oleic acid into MCF7 cells after 30 or 60 min was increased by 67% in H-FABP expressing transfectants, demonstrating a stimulatory role for this FABP-type in fatty acid metabolism. However, preferential targeting of [14C]oleic acid into neutral or phospholipid classes was not observed by the criterion of high performance thin layer chromatography followed by autoradiography. A reason for the modest increase of fatty acid uptake in H-FABP transfected MCF7 cells may be the basal expression of epidermal-type FABP, which was detected for the first time in these cells. It appears that the small amount of E-FABP expressed in MCF7 cells fulfils the need of the cells for a cytosolic fatty acid carrier under culture conditions and that even high concentrations of another FABP do only slightly increase the uptake due to limitations of fatty acid transport through the plasma membrane or of metabolism.
人乳腺癌细胞系MCF7不表达心脏型脂肪酸结合蛋白（H-FABP），这是一种分化乳腺的标记蛋白。用牛H-FABP cDNA转染的MCF7细胞表达相应蛋白，其特征为在裸鼠中生长受抑制且致瘤性降低[22]。通过酶联免疫测定，我们现在确定这些细胞中牛H-FABP的含量为638±80 ng/mg蛋白，并使用转染细胞研究H-FABP在脂肪酸代谢中的作用。与对照细胞相比，在表达H-FABP的转染子中，30或60分钟后放射性标记的棕榈酸和油酸进入MCF7细胞的摄取量增加了67%，表明这种FABP类型在脂肪酸代谢中具有刺激作用。然而，通过高效薄层色谱法继以放射自显影的标准，未观察到[14C]油酸优先靶向中性或磷脂类。在H-FABP转染的MCF7细胞中脂肪酸摄取适度增加的一个原因可能是表皮型FABP的基础表达，这是首次在这些细胞中检测到。似乎在MCF7细胞中表达的少量E-FABP满足了细胞在培养条件下对胞质脂肪酸载体的需求，并且由于脂肪酸通过质膜运输或代谢的限制，即使高浓度的另一种FABP也只会使摄取量略有增加。
