A Novel Regulator of Cancer Cell Migration and Invasion

描述（申请人提供）：细胞骨架和细胞迁移的调控是肿瘤侵袭和转移的一个重要方面。本项目重点研究一种新型蛋白Nischarin，它在细胞迁移和侵袭中具有抑制作用。整合素与细胞过程有关，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。我们已经发现了一种新的蛋白质，它可以与a5细胞质尾部特异性地相互作用；我们称这种蛋白质为“Nischarin”。最近，在Rac1的效应域突变体的帮助下，我们证明Nischarin选择性地抑制通过p21活化激酶（PAK）作用的rac驱动的信号级联反应。这些结果表明Nischarin影响Rac和PAK介导的细胞骨架调节过程。Nischarin与PAK结合，抑制PAK的激酶活性。此外，我们最近的数据表明Nischarin siRNA刺激板足形成和细胞迁移，并激活PAK激酶，表明Nischarin是细胞运动的重要调节剂。本研究旨在进一步研究新发现的PAK与Nischarin之间的生化联系及其在肿瘤细胞迁移和侵袭中的作用。在Aim I中，我们将通过过表达或过低表达Nischarin来解决Nischarin在癌细胞迁移和侵袭中的作用。我们还将研究PAK和Nischarin在假足和侵入足中的时空定位和调控。在Aim II中，我们将研究Nischarin对PAK下游效应物包括LIMK和cofilin的影响，并研究其如何影响癌细胞的侵袭。在Aim中，我们将通过活细胞成像研究板足动力学来评估Nischarin对板足形成的影响；我们将可视化对板足突、板足缩回和膜褶的影响。评估Nischarin和PAK在肿瘤细胞迁移和侵袭调控中的作用，将拓宽目前对癌细胞中PAK信号传导的认识，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.