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 2

Myo10 regulates spreading, migration, and invasion.

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Myo10 regulates spreading, migration, and invasion. (A) shMyo10–expressi...
(A) shMyo10–expressing MDA-MB-231 cell clones analyzed by Western blot for expression of Myo10, Talin-1, β1 integrin, and tubulin. (B) Morphology of shRNA-expressing cells on Matrigel. Shown are cell outlines, calculated cell area, and roundness (inverse of major axis/minor axis). Area units are pixels. n = 25 (shControl); n = 26 (shMyo10). Scale bar: 20 μm. (C) Random migration of shMyo10-expressing (pooled clones no. 1 and no. 2) MDA-MB-231 cells on Matrigel. Cumulative mean square displacement of tracked cells is shown. n = 75 (shControl) and n = 85 (shMyo10). (D) Invasion of shMyo10-expressing (pooled clones no. 1 and no. 2) MDA-MB-231 cells into Matrigel (4 days). Images show side views of invasion. Column graph shows mean invasion areas, and arrows indicate the direction of invasion. n = 10 (shControl); n = 14 (shMyo10) fields of view with ×20 objective. (E) Invasion of MCF-7 cells transfected with EGFP alone or EGFP-Myo10. Column graph shows the percentage of invaded GFP-positive cells from all GFP-positive cells. n = 10 (shControl); n = 8 (shMyo10) fields of view with ×20 objective. (F) Adhesion of shMyo10-expressing (pooled clones no. 1 and no. 2) MDA-MB-231 cells on fibronectin (5 μg/ml) was analyzed at 30- and 60-minute time points as 3 independent experiments. (G) Filopodial phenotype of shMyo10-expressing (pooled clones no. 1 and no. 2) MDA-MB-231 cells spreading actively on fibronectin (5 μg/ml). The number of cells expressing clear filopodial phenotype is shown. n = 21 (shControl); n = 25 (shMyo10). (H) Images show examples of the filopodia phenotype. Scale bar: 20 μm. Mean ± SEM and Mann-Whitney test P values are provided.