Desai Bhavik, Ma Tao, Chellaiah Meenakshi A
Department of Biomedical Sciences, Dental School, University of Maryland, Baltimore, Maryland 21201, USA.
J Biol Chem. 2008 May 16;283(20):13856-66. doi: 10.1074/jbc.M709401200. Epub 2008 Mar 11.
The present study demonstrated that invadopodia are associated with invasion by degradation of matrix in prostate cancer cells PC3. To find out the presence of invadopodia in PC3 cells, we performed a few comparative analyses with osteoclasts, which utilize podosomes for migration. Our investigations indeed demonstrated that invadopodia are comparable to podosomes in the localization of Wiskott-Aldrich syndrome protein (WASP)/matrix metalloproteinase-9 and the degradation of matrix. Invadopodia are different from podosomes in the localization of actin/vinculin, distribution during migration, and the mode of degradation of extracellular matrix. Invadopodia enable polarized invasion of PC3 cells into the gelatin matrix in a time-dependent manner. Gelatin degradation was confined within the periphery of the cell. Osteoclasts demonstrated directional migration with extensive degradation of matrix underneath and around the osteoclasts. A pathway of degradation of matrix representing a migratory track was observed due to the rearrangement of podosomes as rosettes or clusters at the leading edge. Reducing the matrix metalloproteinase-9 levels by RNA interference inhibited the degradation of matrix but not the formation of podosomes or invadopodia. Competition experiments with TAT-fused WASP peptides suggest that actin polymerization and formation of invadopodia involve the WASP-Arp2/3 complex pathway. Moreover, PC3 cells overexpressing osteopontin (OPN) displayed an increase in the number of invadopodia and gelatinolytic activity as compared with PC3 cells and PC3 cells expressing mutant OPN in integrin-binding domain and null for OPN. Thus, we conclude that OPN/integrin alphavbeta3 signaling participates in the process of migration and invasion of PC3 cells through regulating processes essential for the formation and function of invadopodia.
本研究表明，侵袭性伪足与前列腺癌细胞PC3中基质降解介导的侵袭有关。为了确定PC3细胞中侵袭性伪足的存在，我们对破骨细胞进行了一些比较分析，破骨细胞利用足体进行迁移。我们的研究确实表明，侵袭性伪足在威斯科特-奥尔德里奇综合征蛋白（WASP）/基质金属蛋白酶-9的定位和基质降解方面与足体相当。侵袭性伪足在肌动蛋白/纽蛋白的定位、迁移过程中的分布以及细胞外基质的降解方式上与足体不同。侵袭性伪足使PC3细胞能够以时间依赖性方式向明胶基质进行极化侵袭。明胶降解局限于细胞周边。破骨细胞表现出定向迁移，其下方和周围的基质有广泛降解。由于足体在前缘重排形成玫瑰花结或簇，观察到一条代表迁移轨迹的基质降解途径。通过RNA干扰降低基质金属蛋白酶-9水平可抑制基质降解，但不影响足体或侵袭性伪足的形成。用TAT融合的WASP肽进行的竞争实验表明，肌动蛋白聚合和侵袭性伪足的形成涉及WASP-Arp2/3复合物途径。此外，与PC3细胞以及在整合素结合域表达突变型骨桥蛋白且骨桥蛋白缺失的PC3细胞相比，过表达骨桥蛋白（OPN）的PC3细胞侵袭性伪足数量增加且明胶酶活性增强。因此，我们得出结论，OPN/整合素αvβ3信号通过调节侵袭性伪足形成和功能所必需的过程参与PC3细胞的迁移和侵袭过程。
