Regulation of microfilament reorganization and invasiveness of breast cancer cells by kinase dead p21-activated kinase-1
Regulation of microfilament reorganization and invasiveness of breast cancer cells by kinase dead p21-activated kinase-1
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DOI：
10.1074/jbc.275.16.12041
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发表时间：
2000-04-21
影响因子：
4.8
通讯作者：
Kumar, R
中科院分区：
文献类型：
--
作者：
Adam, L;Vadlamudi, R;Kumar, R
在人乳腺上皮癌细胞中，生长因子信号的刺激与侵袭性表型的发展和p21活化激酶（PAK1）的激活有关。为了进一步探讨PAK1在乳腺癌细胞侵袭行为中的作用，本研究以高侵袭性乳腺癌MDA-MB435为模型系统，研究了抑制PAK1活性对控制细胞运动和侵袭性的细胞骨架组分重组的影响。我们的研究结果表明，激酶死亡的K299R PAK1突变体的过表达导致运动表型的抑制以及外源heregulin- β 1缺失或存在时细胞的侵袭性。此外，这些表型变化伴随着焦点粘附点解体的阻断、应力纤维的稳定和细胞扩散的增强，并且依赖于激酶死亡结构域的存在，而独立于PAK1的Rac/cdc42完整（cdc42 /Rac相互结合）结构域的存在。我们还证明，在K299R PAK1表达细胞中，f -肌动蛋白丝通过与肌动蛋白结合蛋白原肌球蛋白和caldesmon的持续共定位而稳定。将这些研究扩展到侵袭性乳腺癌MDA-MB231细胞中，发现激酶缺陷K299R PAK1的条件表达也伴随着持续的细胞扩散、多灶黏附点和侵袭性降低。此外，在乳腺癌细胞中抑制PAK1活性与c-Jun n -末端激酶活性降低、转录因子AP-1 DNA结合活性抑制、以及抑制AP-1启动子驱动的体内转录（已知参与乳腺癌侵袭）。这些发现表明PAK1下游通路在乳腺癌细胞侵袭性表型的发展和维持中起作用。
Stimulation of growth factor signaling has been implicated in the development of invasive phenotype and p21-activated kinase (PAK1) activation in human breast epithelial cancer cells. To further explore the roles of PAK1 in the invasive behavior of breast cancer cells, in the present study we investigated the influence of inhibition of PAK1 activity on the reorganization of cytoskeleton components that control motility and invasiveness of cells, using a highly invasive breast cancer MDA-MB435 as a model system. Our results demonstrate that overexpression of a kinase dead K299R PAK1 mutant leads to suppression of motile phenotypes as well as invasiveness of cells both in the absence or presence of exogenous heregulin-beta 1. In addition, these phenotypic changes were accompanied by a blockade of disassembly of focal adhesion points, stabilization of stress fibers, and enhanced cell spreading and were dependent on the presence of the kinase dead domain but independent of the presence of the Rac/cdc42 intact (Cdc42/Rac interactive binding) domain of PAK1, We also demonstrated that in K299R PAK1-expressing cells, F-actin filaments were stabilized by persistent co-localization with the actin-binding proteins tropomyosin and caldesmon. Extension of these studies to invasive breast cancer MDA-MB231 cells illustrated that conditional expression of kinase-defective K299R PAK1 was also accompanied by persistent cell spreading, multiple focal adhesion points, and reduced invasiveness, Furthermore, inhibition of PAK1 activity in breast cancer cells was associated with a reduction in c-Jun N-terminal kinase activity, inhibition of DNA binding activity of transcription factor AP-1, and suppression of in vivo transcription driven by AP-1 promoter (known to be involved in breast cancer invasion). These findings suggest that PAK1 downstream pathways have a role in the development and maintenance of invasive phenotypes in breast cancer cells.