Mutant p53–associated myosin-X upregulation promotes breast cancer invasion and metastasis
Antti Arjonen, … , Heikki Joensuu, Johanna Ivaska
Antti Arjonen, … , Heikki Joensuu, Johanna Ivaska
Published February 3, 2014
Citation Information: J Clin Invest. 2014;124(3):1069-1082. https://doi.org/10.1172/JCI67280.
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Research Article Oncology

Mutant p53–associated myosin-X upregulation promotes breast cancer invasion and metastasis

Abstract

Mutations of the tumor suppressor TP53 are present in many forms of human cancer and are associated with increased tumor cell invasion and metastasis. Several mechanisms have been identified for promoting dissemination of cancer cells with TP53 mutations, including increased targeting of integrins to the plasma membrane. Here, we demonstrate a role for the filopodia-inducing motor protein Myosin-X (Myo10) in mutant p53–driven cancer invasion. Analysis of gene expression profiles from 2 breast cancer data sets revealed that MYO10 was highly expressed in aggressive cancer subtypes. Myo10 was required for breast cancer cell invasion and dissemination in multiple cancer cell lines and murine models of cancer metastasis. Evaluation of a Myo10 mutant without the integrin-binding domain revealed that the ability of Myo10 to transport β1 integrins to the filopodia tip is required for invasion. Introduction of mutant p53 promoted Myo10 expression in cancer cells and pancreatic ductal adenocarcinoma in mice, whereas suppression of endogenous mutant p53 attenuated Myo10 levels and cell invasion. In clinical breast carcinomas, Myo10 was predominantly expressed at the invasive edges and correlated with the presence of TP53 mutations and poor prognosis. These data indicate that Myo10 upregulation in mutant p53–driven cancers is necessary for invasion and that plasma-membrane protrusions, such as filopodia, may serve as specialized metastatic engines.

Authors

Antti Arjonen, Riina Kaukonen, Elina Mattila, Pegah Rouhi, Gunilla Högnäs, Harri Sihto, Bryan W. Miller, Jennifer P. Morton, Elmar Bucher, Pekka Taimen, Reetta Virtakoivu, Yihai Cao, Owen J. Sansom, Heikki Joensuu, Johanna Ivaska

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Figure 3

Myo10-mediated targeting of integrin to the filopodia tip is critical for invasion.

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Myo10-mediated targeting of integrin to the filopodia tip is critical fo...
(A) Cells expressing EGFP-Myo10 (green) stained with fluorescently labeled β1 integrin antibody (red). Time-lapse images of filopodia dynamics acquired at 10-second intervals. Still images of Myo10 moving back and forth along filopodia are shown. β1 Integrin is mostly seen at the filopodia tip. Scale bar: 5 μm. (B) MDA-MB-231 cells transfected with EGFP-Myo10 and EGFP-Myo10ΔFERM2 and analyzed for filopodia localization. Images show confocal slices at the bottom and the top of the cells. Graph shows the number of dorsal filopodia. Scale bar: 10 μm. (C) MDA-MB-231 cells transfected with EGFP-Myo10 (green) and treated with β1 integrin function–blocking (mAb13) and –activating (12G10) antibodies and stained for filamentous actin. Filopodia lengths were measured along filopodia shafts. Scale bar: 10 μm. (D) Myo10 shRNA–expressing MDA-MB-231 cells (pooled clones no. 1 and no. 2; shMyo10) transfected as indicated and imaged for localization of β1 integrin at the filopodia tips. Representative images are shown. Scale bar: 5 μm. (E, F) shMyo10 cells transfected with EGFP-Myo10 or EGFP-Myo10ΔFERM2 (green) to reconstitute Myo10 expression. Invasion into Matrigel (4 days) was analyzed by detecting all cells with Syto60 staining (white in the merged image) and the transfected cells by EGFP. Images show side view z-stacks. Arrows indicate the direction of invasion. The noninvaded cells at the bottom of the wells are below the red line. n = 6 (EGFP-Myo10) and n = 9 (EGFP-MYO10 ΔFERM) fields of view with ×20 objective. Mean ± SEM and Mann-Whitney test P values are provided.