Characterization of the migratory phenotype of cancer cells selected on IGDQ expressing surface: “PACMAN" project

PhD thesis defended by Sophie AYAMA (Prof. Carine MICHIELS) - 05/07/2021

Prof. Carine MICHIELS, UNamur, Laboratory of Cellular and Molecular Biology - URBC (promoter)

Prof. Davide BONIFAZI, Cardiff University / Vienna University (co-promoter)

  • Stéphane VINCENT (UNamur), président
  • Carine MICHIELS (UNamur), secrétaire
  • Davide BONIFAZI (University of Vienna), co-promoteur
  • Christine GILLES (ULiège)
  • Dr Boris HESPEELS (UNamur)
  • Prof. Nathalie THERET (Université de Rennes 1)

Breast cancer metastasis is the main cause of related deaths, especially triple negative ones (TNBC). No targeted therapies are reported to be efficient in this type of cancer until now. The extracellular matrix (ECM), in particular the fibronectin type I motif IGDQ (IsoLeu-Gly-Asp-Glutamine), plays a major role in cell migration prior the metastasis formation. This motif interacts with specific integrins inducing their activation and the migratory signal transduction. In this work, known as PACMAN (Peptide-Assisted Cellular Migration Along eNgineered surfaces) project, we have shown that IGDQ-exposing monolayers (SAMs) sustain the adhesion and migration of MDA-MB-231 cells by triggering Focal Adhesion Kinase (FAK) by activating integrins. The observed migratory behavior induced by the IGDQ-bearing peptide gradient along the surface suggests the presence of cell subpopulations associated with a “stationary” or a “migratory” phenotype. First, we investigated the role of integrins alpha 5 and beta 3 in collective and IGDQ-mediated single cell migration through their invalidation using shRNA method and a complete proteomic analysis. Our results showed that i) beta 3 integrin depletion influences integrin alpha 5 mRNA expression, ii) integrin beta 3 and integrin alpha 5 are both necessary for IGDQ-mediated directional single cell migration, iii) integrin (αv)β3 is activated by IGDQ fibronectin type I motif and iv) co-regulation of retrograde transport of integrin beta 3 by integrin alpha 5 is potentially necessary for directional IGDQ-mediated cell migration. Secondly, we characterized the migratory phenotype of MDA-MB-231 cells, using functionalized IGDQ-exposing surfaces and whole transcriptome RNA sequencing, and compared it our previous proteomic data. The serine and arginine rich splicing factor 6 (SRSF6) was found to be functionally linked to both integrins and cell migration. Indacaterol was evidenced as a direct pharmacology inhibitor of SRSF6.  The incubation of cells with indacaterol induced: i) the inhibition of collective and IGDQ-mediated cell migration and ii) ITGA5 sequestration into endosomes and lysosomes. Indacaterol is a thus potential therapy to block cell migration and reduce metastasis formation. Further studies will be performed to validate Indacaterol potential as metastasis preventive therapy in TNBC.