Banyard J, Anand-Apte B, Symons M, Zetter B R
Department of Surgical Research, Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
Oncogene. 2000 Jan 27;19(4):580-91. doi: 10.1038/sj.onc.1203338.
Cell migration in vivo often requires invasion through tissue matrices. Currently little is known regarding the signaling pathways that regulate cell invasion through three-dimensional matrices. The small GTPases Cdc42, Rac and Rho are key regulators of actin cytoskeletal and adhesive structures. We now show that expression of dominant negative forms of either Cdc42, Rac or Rho inhibited PDGF-BB-stimulated Rat1 fibroblast invasion into 3D collagen matrices, indicating that the activity of each of these GTPases is necessary for cell invasion. In contrast, only Rac activation was required for PDGF-BB-stimulated locomotion across a planar substrate in the Boyden chamber. Interestingly, PDGF-induced invasion was also strongly inhibited by expression of constitutively active forms of Cdc42 or Rho, and to a lesser extent by constitutively active Rac. We also show that constitutively active V12-Rac significantly stimulated basal Rat1 fibroblast invasion, independent of PI-3-kinase activity, and that this effect was suppressed by the effector mutant V12/H40-Rac. These results suggest that cellular invasion may require an optimal level of activation of Cdc42, Rho and Rac, and that migration and invasion are differentially modulated by Rho family GTPases.
细胞在体内迁移通常需要穿过组织基质。目前，关于调节细胞穿过三维基质的信号通路知之甚少。小GTP酶Cdc42、Rac和Rho是肌动蛋白细胞骨架和黏附结构的关键调节因子。我们现在表明，Cdc42、Rac或Rho的显性负性形式的表达抑制了血小板衍生生长因子BB（PDGF-BB）刺激的大鼠1型成纤维细胞侵入三维胶原基质，这表明这些GTP酶中的每一种的活性对于细胞侵入都是必需的。相比之下，在博伊登小室中，PDGF-BB刺激的细胞在平面基质上的移动仅需要Rac激活。有趣的是，PDGF诱导的侵入也被Cdc42或Rho的组成型活性形式的表达强烈抑制，而被组成型活性Rac的抑制程度较小。我们还表明，组成型活性的V12-Rac显著刺激大鼠1型成纤维细胞的基础侵入，与磷脂酰肌醇-3激酶（PI-3-激酶）活性无关，并且这种效应被效应突变体V12/H40-Rac抑制。这些结果表明，细胞侵入可能需要Cdc42、Rho和Rac的最佳激活水平，并且迁移和侵入受到Rho家族GTP酶的不同调节。
