Abstract 5063: The receptor for urokinase-plasminogen activator controls plasticity of cancer cell movement in mesenchymal and amoeboid migration style
Authors: Chillà Anastasia , Margheri Francesca , Laurenzana Anna , Luciani Cristina , Biagioni Alessio , Fibbi Gabriella , Del Rosso Mario 
Published: July 2016

Abstract
Introduction. The receptor for the urokinase plasminogen activator (uPAR) is up-regulated in malignant tumors. Historically the function of uPAR in cancer cell invasion is strictly related to its property to promote uPA-dependent proteolysis of extracellular matrix and to open a path to malignant cells. These features are typical of mesenchymal motility.
Materials and methods. To evaluate the mesenchymal ameboid transition we performed RhoA and Rac1 activation assay, immunofluorescence analysis of protein involved in cytoskeleton organization, and collagen degradation assay. For a clear visualization of collagen fiber breakdown in the process of proteolytic migration we used reconstruction by time-lapse video microscopy. Cell invasion was studied in Boyden chambers using filters coated with Matrigel. uPAR gene expression was inhibited using a 18-mer phosphorothioate aODN, and as a negative control we used a degenerated oligodeoxynucleotide, which is a mixture of all possible combinations of bases that compose the aODN.
Results and discussion. Here we show that the full-length form of uPAR is required when prostate and melanoma cancer cells convert their migration style from the “path generating” mesenchymal to the “path finding” amoeboid one, thus conferring a plasticity to tumor cell invasiveness across three-dimensional matrices. Indeed, in response to a protease inhibitors-rich milieu, prostate and melanoma cells activated an amoeboid invasion program connoted by retraction of cell protrusions, RhoA-mediated rounding of the cell body, formation of a cortical ring of actin and a reduction of Rac-1 activation. While the mesenchymal movement was reduced upon silencing of uPAR expression, the amoeboid one was almost completely abolished, in parallel with a deregulation of small Rho-GTPases activity. In melanoma and prostate cancer cells we have shown uPAR colocalization with β1/β3 integrins and actin cytoskeleton, as well integrins-actin co-localization under both mesenchymal and amoeboid conditions. Such co-localizations were lost upon treatment of cells with a peptide that inhibits uPAR-integrin interactions. Similarly to uPAR silencing, the peptide reduced mesenchymal invasion and almost abolished the amoeboid one.
Conclusion. These results indicate that full-length uPAR bridges the mesenchymal and amoeboid style of movement by an inward-oriented activity based on its property to promote integrin-actin interactions and the following cytoskeleton assembly.
Citation Format: Anastasia Chillà, Francesca Margheri, Anna Laurenzana, Cristina Luciani, Alessio Biagioni, Gabriella Fibbi, Mario Del Rosso. The receptor for urokinase-plasminogen activator controls plasticity of cancer cell movement in mesenchymal and amoeboid migration style. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5063.