Distinct roles of nonmuscle myosin II isoforms in the regulation of MDA-MB-231 breast cancer cell spreading and migration
Distinct roles of nonmuscle myosin II isoforms in the regulation of MDA-MB-231 breast cancer cell spreading and migration
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DOI：
10.1158/0008-5472.can-05-4236
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发表时间：
2006-05-01
期刊：
影响因子：
11.2
通讯作者：
Egelhoff, Thomas T.
中科院分区：
文献类型：
--
作者：
Betapudi, Venkaiah;Licate, Lucila S.;Egelhoff, Thomas T.
肿瘤细胞转移的初始阶段涉及上皮-间充质细胞的转变，包括激活阿米巴迁移和细胞-细胞黏附的丧失。肌动蛋白细胞骨架在这些事件中具有基础但知之甚少的作用。肌球蛋白II是一种丰富的生力蛋白，在细胞迁移过程中参与细胞体的移位和细胞后部的收缩。最近的研究表明，这种蛋白质也可能在前沿突出事件中发挥作用。转移促进蛋白转移促进蛋白-1，肌球蛋白II组装的调节者，与肌球蛋白IIA共同定位在癌细胞的前沿，提示肌球蛋白II在转移行为中直接作用。我们已经评估了特定的肌球蛋白II亚型在MDA-MB-231乳腺癌细胞在细胞外基质上板层扩散过程中的作用。我们发现，两种主要的肌球蛋白II亚型IIA和IIB都在这些细胞中表达，并且在纤维连接蛋白的活跃扩散过程中，这两种亚型都被戏剧性地招募到板层边缘。调节轻链磷酸化也有一过性的增加，这与肌球蛋白IIA和肌球蛋白IIB的募集进入这一扩散边缘相关。肌球蛋白II或肌球蛋白轻链激酶的药物抑制显著减少了扩散。通过小干扰RNA耗尽肌球蛋白IIA可抑制迁移但促进板层铺展，而耗尽肌球蛋白IIB不仅可削弱迁移，还可降低板层铺展的初始速率。这些结果表明，这两种异构体对细胞迁移的机制都是至关重要的，肌球蛋白IIB似乎在板层突起的机制中具有优先的作用。
Initial stages of tumor cell metastasis involve an epithelial-mesenchyme transition that involves activation of amoeboid migration and loss of cell-cell adhesion. The actomyosin cytoskeleton has fundamental but poorly understood roles in these events. Myosin II, an abundant force-producing protein, has roles in cell body translocation and retraction of the posterior of the cell during migration. Recent studies have suggested that this protein may also have roles in leading edge protrusive events. The metastasis-promoting protein metastasin-1, a regulator of myosin II assembly, colocalizes with myosin IIA at the leading edge of cancer cells, suggesting direct roles for myosin II in metastatic behavior. We have assessed the roles of specific myosin II isoforms during lamellar spreading of MDA-MB-231 breast cancer cells on extracellular matrix. We find that the two major myosin II isoforms IIA and IIB are both expressed in these cells, and both are recruited dramatically to the lamellar margin during active spreading on fibronectin. There is also a transient increase in regulatory light chain phosphorylation that correlates the recruitment of myosin IIA and myosin IIB into this spreading margin. Pharmacologic inhibition of myosin II or myosin light chain kinase dramatically reduced spreading. Depletion of myosin IIA via small interfering RNA impaired migration but enhanced lamellar spreading, whereas depletion of myosin IIB impaired not only migration but also impaired initial rates of lamellar spreading. These results indicate that both isoforms are critical for the mechanics of cell migration, with myosin IIB seeming to have a preferential role in the mechanics of lamellar protrusion.