MDA - 468乳腺肿瘤细胞中磷脂酶C - γ1的膜结合增加。

Elevated membrane association of phospholipase C-gamma 1 in MDA-468 mammary tumor cells.

作者信息

Soderquist A M, Todderud G, Carpenter G

机构信息

Department of Biochemistry, Vanderbilt University of School of Medicine, Nashville 37232-0146.

出版信息

Cancer Res. 1992 Aug 15;52(16):4526-9.

PMID:1643644

Abstract

We have examined the distribution of phospholipase C-gamma 1 (PLC-gamma 1) between membrane and cytosolic fractions in several cell lines. In MDA-468 cells, which are derived from a human breast tumor, greater than one-half of the total PLC-gamma 1 is associated with the membrane fraction of the cell. Unlike the situation in A-431 cells [G. Todderud, M. I. Wahl, S. G. Ree, and G. Carpenter, Science, 248: 296-298, 1990], epidermal growth factor (EGF) stimulation of MDA-468 cells does not result in significantly increased PLC-gamma 1 association with membranes. Immunoblot analysis reveals low levels of phosphotyrosine in PLC-gamma 1 and EGF receptors in unstimulated MDA-468 cells and greatly increased phosphotyrosine levels in these proteins as a result of EGF stimulation of the cells. We conclude that autocrine activation of EGF receptors is not responsible for the elevated association of PLC-gamma 1 with membranes in these cells.

摘要

我们研究了磷脂酶C-γ1（PLC-γ1）在几种细胞系的膜组分和胞质组分之间的分布。在源自人类乳腺肿瘤的MDA-468细胞中，超过一半的总PLC-γ1与细胞的膜组分相关联。与A-431细胞中的情况不同[G. Todderud，M. I. Wahl，S. G. Ree和G. Carpenter，《科学》，248：296 - 298，1990]，表皮生长因子（EGF）刺激MDA-468细胞并不会导致PLC-γ1与膜的结合显著增加。免疫印迹分析显示，未受刺激的MDA-468细胞中，PLC-γ1和EGF受体中的磷酸酪氨酸水平较低，而细胞经EGF刺激后，这些蛋白质中的磷酸酪氨酸水平大幅增加。我们得出结论，EGF受体的自分泌激活并非这些细胞中PLC-γ1与膜结合增加的原因。