title: Active invadopodia of mesenchymally migrating cancer cells contain both β and γ cytoplasmic actin isoforms.
abstract: Invadopodia are actin-rich protrusions formed by mesenchymally migrating cancer cells. They are mainly composed of actin, actin-associated proteins, integrins and proteins of signaling machineries. These protrusions display focalized proteolytic activity towards the extracellular matrix. It is well known that polymerized (F-)actin is present in these structures, but the nature of the actin isoform has not been studied before. We here show that both cytoplasmic actin isoforms, β- and γ-actin, are present in the invadopodia of MDA-MB-231 breast cancer cells cultured on a 2D-surface, where they colocalize with the invadopodial marker cortactin. Invadopodial structures formed by the cells in a 3D-collagen matrix also contain β- and γ-actin. We demonstrate this using isoform-specific antibodies and expression of fluorescently-tagged actin isoforms. Additionally, using simultaneous expression of differentially tagged β- and γ-actin in cells, we show that the actin isoforms are present together in a single invadopodium. Cells with an increased level of β- or γ-actin, display a similar increase in the number and size of invadopodia in comparison to control cells. Moreover, increasing the level of either actin isoforms also increases invasion velocity.
authors.affiliation: Department of Cell Pathology, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, 50-383 Wroclaw, Poland. Electronic address: olaw@ibmb.uni.wroc.pl.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Simiczyjew
authors.affiliation: Department of Cell Pathology, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, 50-383 Wroclaw, Poland.
authors.forename: Antonina Joanna
authors.initials: AJ
authors.lastname: Mazur
authors.affiliation: Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Albert Baertsoenkaai 3, B-9000 Ghent, Belgium.
authors.forename: Christophe
authors.initials: C
authors.lastname: Ampe
authors.affiliation: Department of Cell Pathology, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, 50-383 Wroclaw, Poland.
authors.forename: Maria
authors.initials: M
authors.lastname: Malicka-Błaszkiewicz
authors.affiliation: Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Albert Baertsoenkaai 3, B-9000 Ghent, Belgium.
authors.forename: Marleen
authors.initials: M
authors.lastname: van Troys
authors.affiliation: Department of Cell Pathology, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, 50-383 Wroclaw, Poland.
authors.forename: Dorota
authors.initials: D
authors.lastname: Nowak
mesh_terms: D000199:Actins / Q000378:metabolism*; D002465:Cell Movement; D003593:Cytoplasm / Q000378:metabolism*; D006801:Humans; D008648:Mesoderm / Q000378:metabolism / Q000473:pathology*; D000069261:Podosomes / Q000378:metabolism* / Q000473:pathology; D020033:Protein Isoforms / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D000199:Actins; D020033:Protein Isoforms
keywords: Cancer cells invasion; Cytoplasmic actin isoforms; Invadopodia