Kwiatkowska Aneta, Kijewska Magdalena, Lipko Maciej, Hibner Urszula, Kaminska Bozena
Laboratory of Transcription Regulation, Department of Cell Biology, Nencki Institute of Experimental Biology, 3 Pasteur Str., 02-093 Warsaw, Poland.
Biochim Biophys Acta. 2011 May;1813(5):655-67. doi: 10.1016/j.bbamcr.2011.01.020. Epub 2011 Jan 26.
Human malignant glioblastomas are highly invasive tumors. Increased cell motility and degradation of the surrounding extracellular matrix are essential for tumor invasion. PI3K/Akt signaling pathway emerges as a common pathway regulating cellular proliferation, migration and invasion; however, its contribution to particular process and downstream cascades remain poorly defined. We have previously demonstrated that Cyclosporin A (CsA) affects glioblastoma invasion in organotypic brain slices and tumorigenicity in mice. Here we show that CsA impairs migration and invasion of human glioblastoma cells by downregulation of Akt phosphorylation. Interference with PI-3K/Akt signaling was crucial for CsA effect on invasion, because overexpression of constitutively active myr-Akt antagonized drug action. Furthermore, the drug was not effective in T98G glioblastoma cells with constitutively high level of phosphorylated Akt. CsA, comparably to pharmacological inhibitors of PI3K/Akt signaling (LY294002, A443654), reduced motility of glioblastoma cells, diminished MMP-2 gelatinolytic activity and MMP-2 and MT1-MMP expression. The latter effect was mimicked by overexpression of dominant negative Akt mutants. We demonstrate that CsA and LY294002 reduced MMP transcription partly via modulation of IκB phosphorylation and NFκB transcriptional activity. Those effects were not mediated by inhibition of calcineurin, a classical CsA target. Additionally, CsA reduced phosphorylation and activity of focal adhesion kinase that was associated with rapid morphological alterations, rearrangement of lamellipodia and impairment of MT1-MMP translocation to membrane protrusions. Our results document novel, Akt-dependent mechanisms of interference with motility/invasion of human glioblastoma cells: through a rapid modulation of cell adhesion and MT1-MMP translocation to membrane protrusions and delayed, partly NFκB-dependent, downregulation of MMP-2 and MT1-MMP expression. This article is part of a Special Issue entitled: 11th European Symposium on Calcium.
人类恶性胶质母细胞瘤是具有高度侵袭性的肿瘤。细胞运动性增加和周围细胞外基质的降解是肿瘤侵袭的关键。PI3K/Akt信号通路是调节细胞增殖、迁移和侵袭的常见通路；然而，其对特定过程和下游级联反应的作用仍不清楚。我们之前已经证明，环孢素A（CsA）会影响器官型脑切片中胶质母细胞瘤的侵袭以及小鼠中的致瘤性。在此我们表明，CsA通过下调Akt磷酸化来损害人胶质母细胞瘤细胞的迁移和侵袭。干扰PI-3K/Akt信号对于CsA对侵袭的作用至关重要，因为组成型活性myr-Akt的过表达会拮抗药物作用。此外，该药物对磷酸化Akt水平持续较高的T98G胶质母细胞瘤细胞无效。与PI3K/Akt信号通路的药理学抑制剂（LY294002、A443654）类似，CsA降低了胶质母细胞瘤细胞的运动性，减少了MMP-2的明胶酶活性以及MMP-2和MT1-MMP的表达。显性负性Akt突变体的过表达模拟了后一种效应。我们证明，CsA和LY294002部分通过调节IκB磷酸化和NFκB转录活性来降低MMP转录。这些效应不是由经典的CsA靶点钙调神经磷酸酶的抑制介导的。此外，CsA降低了粘着斑激酶的磷酸化和活性，这与快速的形态改变、片状伪足的重排以及MT1-MMP向膜突出部位的转运受损有关。我们的结果证明了干扰人胶质母细胞瘤细胞运动性/侵袭的新的、依赖Akt的机制：通过快速调节细胞粘附和MT1-MMP向膜突出部位的转运以及延迟的、部分依赖NFκB的MMP-2和MT1-MMP表达下调。本文是名为：第11届欧洲钙研讨会的特刊的一部分。
