Rnd3 regulation of the actin cytoskeleton promotes melanoma migration and invasive outgrowth in three dimensions.
Rnd3 regulation of the actin cytoskeleton promotes melanoma migration and invasive outgrowth in three dimensions.
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DOI：
10.1158/0008-5472.can-08-3201
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发表时间：
2009-03-15
期刊：
影响因子：
11.2
通讯作者：
Aplin AE
中科院分区：
文献类型：
--
作者：
Klein RM;Aplin AE
细胞侵入真皮的深度是皮肤黑色素瘤预后不良的临床决定因素。促进非侵袭性肿瘤表型向侵袭性肿瘤表型转变的信号传导事件仍然不清楚。丝氨酸/苏氨酸激酶B-RAF的激活突变在黑色素瘤中普遍存在。突变体B-RAF是黑色素瘤细胞侵袭所必需的。Rnd 3是Rho家族的一种GT3，其表达受突变型B-RAF调控，但其在黑色素瘤进展中的作用尚不清楚。在这项研究中，我们确定了Rnd 3对侵袭性黑色素瘤的功能贡献。在侵袭性人黑色素瘤细胞中，使用强力霉素诱导的shRNA系统靶向敲低内源性Rnd 3。Rnd 3的耗尽促进突出的肌动蛋白应力纤维和扩大的局灶性粘连。从机制上讲，Rnd 3敲低诱导的应力纤维形成需要RhoA和ROCK 1/2活性的特异性参与，但不需要RhoB或RhoC。Rnd 3在人黑色素瘤细胞系中的表达与ERK磷酸化水平升高和3-D真皮样环境中的侵袭行为密切相关。Rnd 3在黑色素瘤肿瘤球体的侵袭性生长中的功能作用得到证实。Rnd 3的敲除减少了包埋在胶原凝胶中的球状体的侵入性生长。此外，Rnd 3耗竭抑制集体和边界细胞的运动，从球体中的ROCK 1/2依赖的方式。总的来说，这些研究结果暗示Rnd 3作为RhoA介导的肌动蛋白细胞骨架组织的主要抑制因子，并参与侵袭性黑色素瘤表型的获得。
Depth of cell invasion into the dermis is a clinical determinant for poor prognosis in cutaneous melanoma. The signaling events that promote the switch from a non-invasive to invasive tumor phenotype remain obscure. Activating mutations in the serine/threonine kinase B-RAF are prevalent in melanoma. Mutant B-RAF is required for melanoma cell invasion. The expression of Rnd3, a Rho family GTPase, is regulated by mutant B-RAF, although its role in melanoma progression is unknown. In this study, we determined the functional contribution of Rnd3 to invasive melanoma. Endogenous Rnd3 was targeted for knockdown using a doxycyclineinducible shRNA system in invasive human melanoma cells. Depletion of Rnd3 promoted prominent actin stress fibers and enlarged focal adhesions. Mechanistically, stress fiber formation induced by Rnd3 knockdown required the specific involvement of RhoA and ROCK1/2 activity but not RhoB or RhoC. Rnd3 expression in human melanoma cell lines was strongly associated with elevated ERK phosphorylation and invasive behavior in a 3-D dermal-like environment. A functional role for Rnd3 was demonstrated in the invasive outgrowth of melanoma tumor spheroids. Knockdown of Rnd3 reduced invasive outgrowth of spheroids embedded in collagen gels. Additionally, Rnd3 depletion inhibited collective and border cell movement out from spheroids in a ROCK1/2-dependent manner. Collectively, these findings implicate Rnd3 as a major suppressor of RhoA mediated actin cytoskeletal organization and in the acquisition of an invasive melanoma phenotype.