A Novel Regulator of Cancer Cell Migration and Invasion

描述（由申请人提供）：细胞骨架和细胞迁移的调节是癌症侵袭和转移的重要方面。该项目的重点是一种新的蛋白质，Nischarin，在细胞迁移和入侵中具有抑制作用。整合素参与细胞过程，包括肌动蛋白细胞骨架的组织、细胞生长和存活、细胞运动和细胞侵袭。我们已经确定了一种新的蛋白质，特别是相互作用的α 5胞质尾，我们已经将这种蛋白质的Nischarin。最近，在Rac 1的效应结构域突变体的帮助下，我们证明Nischarin选择性地抑制Rac驱动的信号级联反应，该信号级联反应通过p21激活的激酶（PAK）起作用。这些观察结果表明，Nischarin影响由Rac和PAK介导的细胞骨架调节过程。与此一致，Nischarin结合PAK，并抑制PAK的激酶活性。此外，我们最近的数据表明Nischarin siRNA刺激板状伪足形成和细胞迁移，并激活PAK激酶，表明Nischarin是细胞运动的重要调节剂。该提案的目的是进一步研究PAK和Nischarin之间的新描述的生化联系及其在肿瘤细胞迁移和侵袭中的作用。在目的I中，我们将通过Nischarin的过表达或低表达来解决Nischarin在癌细胞的迁移和侵袭中的作用。我们也将研究PAK和Nischarin在伪足和侵袭伪足中的时空定位和调控。在目的II中，我们将研究Nischarin对PAK下游效应物（包括LIMK和cofilin）的影响，并将研究这如何影响癌细胞的侵袭。在目的，我们将评估Nischarin对板状伪足形成的影响，通过研究板状伪足的动力学与活细胞成像;我们将可视化对板状伪足突起，板状伪足收缩和膜皱褶的影响。对Nischarin和PAK在肿瘤细胞迁移和侵袭中的作用的评价将拓宽目前对PAK信号在癌细胞中的理解，并可能为治疗干预提供新的途径。

DESCRIPTION (provided by applicant): Regulation of the cytoskeleton and cell migration is an important aspect of cancer invasion and metastasis. This project focuses on a novel protein, Nischarin that has an inhibitory role in cell migration and invasion. Integrins have been implicated in cellular processes including the organization of actin cytoskeleton, cell growth and survival, cell motility and cell invasion. We have identified a novel protein that specifically interacts with the a5 cytoplasmic tail; we have termed this protein 'Nischarin'. Recently, with the help of effector domain mutants of Rac1, we demonstrated that Nischarin selectively inhibits Rac-driven signaling cascades that act through p21 activated kinase (PAK). These observations suggest that Nischarin affects the process of cytoskeletal regulation mediated by Rac and PAK. Consistent with this, Nischarin binds to PAK, and inhibits the kinase activity of PAK. Furthermore, our recent data indicate that Nischarin siRNA stimulates lamellipodia formation and cell migration, and activates PAK kinase, suggesting that Nischarin is an important regulator of cell motility. The intent of the proposal is to investigate further the newly described biochemical connection between PAK and Nischarin and its role in tumor cell migration and invasion. In Aim I we will address the role of Nischarin in the migration and invasion of carcinoma cells by over or underexpressing Nischarin. Also we will examine spatio-temporal localization and regulation of PAK and Nischarin in pseudopodia and invadopodia. In Aim II, we will study the effect of Nischarin on downstream effectors of PAK including LIMK and cofilin, and will examine how this affects invasion of cancer cells. In Aim we will evaluate Nischarin's effects on lamellipodia formation by studying lamellipodial dynamics with live cell imaging; we will visualize the effects on lamellipodial protrusion, lamellipodial retraction and membrane ruffles. Evaluation of the role of Nischarin and PAK in the regulation of tumor cell migration and invasion will broaden the current understanding of PAK signaling in carcinoma cells, and may provide new avenues for therapeutic intervention.