Department of Oral Biology, LSU Health Sciences Center, New Orleans, LA 70112, USA.
J Cell Sci. 2010 Feb 1;123(Pt 3):401-12. doi: 10.1242/jcs.052167. Epub 2010 Jan 5.
CXCR4 is a chemokine receptor often found aberrantly expressed on metastatic tumor cells. To investigate CXCR4 signaling in tumor cell adhesion, we stably overexpressed CXCR4 in MCF7 breast tumor cells. Cell attachment assays demonstrate that stimulation of the receptor with its ligand, CXCL12, promotes adhesion of MCF7-CXCR4 cells to both extracellular matrix and endothelial ligands. To more closely mimic the conditions experienced by a circulating tumor cell, we performed the attachment assays under shear stress conditions. We found that CXCL12-induced tumor cell attachment is much more pronounced under flow. ROCK is a serine/threonine kinase associated with adhesion and metastasis, which is regulated by CXCR4 signaling. Thus, we investigated the contribution of ROCK activity during CXC12-induced adhesion events. Our results demonstrate a biphasic regulation of ROCK in response to adhesion. During the initial attachment, inhibition of ROCK activity is required. Subsequently, re-activation of ROCK activity is required for maturation of adhesion complexes and enhanced tumor cell migration. Interestingly, CXCL12 partially reduces the level of ROCK activity generated by attachment, which supports a model in which stimulation with CXCL12 regulates tumor cell adhesion events by providing an optimal level of ROCK activity for effective migration.
趋化因子受体 4（CXCR4）是一种趋化因子受体，常异常表达于转移性肿瘤细胞上。为了研究 CXCR4 信号在肿瘤细胞黏附中的作用，我们在 MCF7 乳腺癌细胞中稳定过表达 CXCR4。细胞黏附实验表明，受体受其配体 CXCL12 刺激后，促进 MCF7-CXCR4 细胞与细胞外基质和内皮配体的黏附。为了更接近模拟循环肿瘤细胞所经历的条件，我们在切变应力条件下进行了黏附实验。我们发现，在流动条件下，CXCL12 诱导的肿瘤细胞黏附更为明显。ROCK 是一种与黏附和转移相关的丝氨酸/苏氨酸激酶，受 CXCR4 信号调控。因此，我们研究了 ROCK 活性在 CXCL12 诱导的黏附事件中的作用。结果表明，ROCK 对黏附有双相调节作用。在初始黏附过程中，需要抑制 ROCK 活性。随后，需要重新激活 ROCK 活性，以成熟黏附复合物并增强肿瘤细胞迁移。有趣的是，CXCL12 部分降低了黏附产生的 ROCK 活性水平，这支持了一种模型，即 CXCL12 的刺激通过为有效的迁移提供最佳的 ROCK 活性水平来调节肿瘤细胞黏附事件。
