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Open Access Research article

PAI-1 and functional blockade of SNAI1 in breast cancer cell migration

Elizabeth Fabre-Guillevin12, Michel Malo1, Amandine Cartier-Michaud1, Hector Peinado3, Gema Moreno-Bueno4, Benoît Vallée16, Daniel A Lawrence5, José Palacios4, Amparo Cano3, Georgia Barlovatz-Meimon16* and Cécile Charrière-Bertrand16

Author Affiliations

1 DYNAMIC Team, IBISC FRE 3190 CNRS – Université d'Evry Val d'Essonne, Genopole, Evry 91000, France

2 Department of Medical Oncology, Hopital Européen Georges Pompidou, Paris cedex 15 75908, France

3 Departamento de Bioquímica, Instituto de Investigaciones Biomedicas 'Alberto Sols', (CSIC-UAM), Madrid 28029, Spain

4 Molecular Pathology Program, Centro Nacional de Investigaciones Oncologicas (CNIO), Madrid 28029, Spain

5 Department of Internal Medicine, University of Michigan School of Medicine, Ann Arbor MI 48109-0644, USA

6 University Paris 12 – Val de Marne, Créteil cedex 94010, France

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Breast Cancer Research 2008, 10:R100  doi:10.1186/bcr2203

Published: 3 December 2008

Abstract

Introduction

Snail, a family of transcriptional repressors implicated in cell movement, has been correlated with tumour invasion. The Plasminogen Activation (PA) system, including urokinase plasminogen activator (uPA), its receptor and its inhibitor, plasminogen activator inhibitor type 1(PAI-1), also plays a key role in cancer invasion and metastasis, either through proteolytic degradation or by non-proteolytic modulation of cell adhesion and migration. Thus, Snail and the PA system are both over-expressed in cancer and influence this process. In this study we aimed to determine if the activity of SNAI1 (a member of the Snail family) is correlated with expression of the PA system components and how this correlation can influence tumoural cell migration.

Methods

We compared the invasive breast cancer cell-line MDA-MB-231 expressing SNAI1 (MDA-mock) with its derived clone expressing a dominant-negative form of SNAI1 (SNAI1-DN). Expression of PA system mRNAs was analysed by cDNA microarrays and real-time quantitative RT-PCR. Wound healing assays were used to determine cell migration. PAI-1 distribution was assessed by immunostaining.

Results

We demonstrated by both cDNA microarrays and real-time quantitative RT-PCR that the functional blockade of SNAI1 induces a significant decrease of PAI-1 and uPA transcripts. After performing an in vitro wound-healing assay, we observed that SNAI1-DN cells migrate more slowly than MDA-mock cells and in a more collective manner. The blockade of SNAI1 activity resulted in the redistribution of PAI-1 in SNAI1-DN cells decorating large lamellipodia, which are commonly found structures in these cells.

Conclusions

In the absence of functional SNAI1, the expression of PAI-1 transcripts is decreased, although the protein is redistributed at the leading edge of migrating cells in a manner comparable with that seen in normal epithelial cells.