SSeCKS/Gravin/AKAP12 Inhibits Cancer Cell Invasiveness and Chemotaxis by Suppressing a Protein Kinase C-Raf/MEK/ERK Pathway
SSeCKS/Gravin/AKAP12 Inhibits Cancer Cell Invasiveness and Chemotaxis by Suppressing a Protein Kinase C-Raf/MEK/ERK Pathway
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DOI：
10.1074/jbc.m109.073494
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发表时间：
2010-02-12
影响因子：
4.8
通讯作者：
Gelman, Irwin H.
中科院分区：
文献类型：
--
作者：
Su, Bing;Bu, Yahao;Gelman, Irwin H.
SSeCKS/Gravin/AKAP12(“SSeCKS”)编码一种细胞骨架蛋白，通过构建细胞周期蛋白、蛋白激酶C和蛋白激酶A来调节G(1)>；S的进程。SSeCKS在包括前列腺癌在内的许多肿瘤类型中表达下调，当在Mat-LyLu(MLL)前列腺癌细胞中重新表达时，SSeCKS通过抑制远端新生血管来选择性地抑制转移，这与其下调包括Vegfa在内的促血管生成基因的能力有关。然而，强制重新表达血管内皮生长因子只能挽救部分肺转移的形成。在这里，我们证明了SSeCKS有效地抑制了趋化和Matrigel侵袭，这是有助于转移形成的运动性参数。SSeCKS抑制血清诱导的Raf/MEK/ERK通路的激活，导致基质金属蛋白酶-2表达下调。相反，SSeCKS对血清诱导的Src底物Shc的磷酸化没有影响，这与我们之前的数据一致，即SSeCKS不抑制细胞中Src激酶的活性。MEK1、MEK2、ERK1或PKCα的强制表达可恢复细胞的侵袭性和趋化性。SSeCKS只有在编码其PKC结合区(氨基酸553-900)的情况下才能抑制佛波酯诱导的ERK1/2活性，这表明SSeCKS通过直接支架传统的和/或新型的PKC同工酶来减弱ERK的激活。最后，SSeCKS对MLL侵袭性的控制受到肌动蛋白细胞骨架的影响：SSeCKS抑制足体形成的能力不受细胞松弛素D或茉莉花激内酯的影响，而其抑制MEK1/2和ERK1/2激活的能力则被茉莉花激动素抵消。我们的研究结果表明，SSeCKS通过解离激活的Src，然后抑制PKC-Raf/MEK/ERK通路，控制基质金属蛋白酶-2的表达和足体的形成，从而抑制肿瘤的转移。
SSeCKS/Gravin/AKAP12 ("SSeCKS") encodes a cytoskeletal protein that regulatesG(1)-> S progression by scaffolding cyclins, protein kinase C (PKC) and PKA. SSeCKS is down-regulated in many tumor types including prostate, and when re-expressed in MAT-LyLu (MLL) prostate cancer cells, SSeCKS selectively inhibits metastasis by suppressing neovascularization at distal sites, correlating with its ability to down-regulate proangiogenic genes including Vegfa. However, the forced re-expression of VEGF only rescues partial lung metastasis formation. Here, we show that SSeCKS potently inhibits chemotaxis and Matrigel invasion, motility parameters contributing to metastasis formation. SSeCKS suppressed serum-induced activation of the Raf/MEK/ERK pathway, resulting in down-regulation of matrix metalloproteinase-2 expression. In contrast, SSeCKS had no effect on serum-induced phosphorylation of the Src substrate, Shc, in agreement with our previous data that SSeCKS does not inhibit Src kinase activity in cells. Invasiveness and chemotaxis could be restored by the forced expression of constitutively active MEK1, MEK2, ERK1, or PKC alpha. SSeCKS suppressed phorbol ester-induced ERK1/2 activity only if it encoded its PKC binding domain (amino acids 553-900), suggesting that SSeCKS attenuates ERK activation through a direct scaffolding of conventional and/or novel PKC isozymes. Finally, control of MLL invasiveness by SSeCKS is influenced by the actin cytoskeleton: the ability of SSeCKS to inhibit podosome formation is unaffected by cytochalasin D or jasplakinolide, whereas its ability to inhibit MEK1/2 and ERK1/2 activation is nullified by jasplakinolide. Our findings suggest that SSeCKS suppresses metastatic motility by disengaging activated Src and then inhibiting the PKC-Raf/MEK/ERK pathways controlling matrix metalloproteinase-2 expression and podosome formation.