title: Alteration of cathepsin D trafficking induced by hypoxia and extracellular acidification in MCF-7 breast cancer cells.
abstract: The microenvironment that surrounds tumor cells is characterized by hypoxic conditions and extracellular acidity. These hostile conditions induce crucial changes in cell behavior and can promote the secretion of many soluble factors such as growth factors, cytokines and enzymes. The lysosomal aspartyl-endopeptidase cathepsin D (CD) is a marker of poor prognosis in breast cancer and is associated with a metastatic risk. In this study, the transport of CD was investigated in a model of breast cancer cells line (MCF-7) cultivated under hypoxia and acidification of media. CD secretion was assessed using Western blot analysis and protease activity was measured in conditioned culture media. We demonstrate that cultured MCF-7 cells secrete an active 52 kDa pCD precursor and report that under hypoxia there was an increased amount of pCD secreted. More surprisingly, extracellular acidification (pH 6 and 5.6) induced the secretion of the fully-mature and active (34 kDa + 14 kDa) double chain CD. Our findings reflect the fact that chemical anomalies influence the secretion path of CD in a breast cancer cell model, resulting in altered trafficking of the mature form. This important result may provide new arguments in favor of the role of extracellular CD in the degradation of the matrix proteins that constitute the breast tumor microenvironment.
authors.affiliation: Université de La Rochelle, UMR CNRS 7266, LIENSs, Equipe Approches Moléculaires, Environnement-Santé, Département de Biotechnologies, Avenue Michel Crépeau, 17042 La Rochelle, France.
authors.forename: Oussama
authors.initials: O
authors.lastname: Achour
authors.affiliation: Institut de Recherche en Cancérologie de Montpellier (IRCM), Institut National de la Santé et de la Recherche Médicale (INSERM) U896, Université Montpellier1, Montpellier, France.
authors.forename: Yahya
authors.initials: Y
authors.lastname: Ashraf
authors.affiliation: Université de La Rochelle, UMR CNRS 7266, LIENSs, Equipe Approches Moléculaires, Environnement-Santé, Département de Biotechnologies, Avenue Michel Crépeau, 17042 La Rochelle, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Bridiau
authors.affiliation: Université de La Rochelle, UMR CNRS 7266, LIENSs, Equipe Approches Moléculaires, Environnement-Santé, Département de Biotechnologies, Avenue Michel Crépeau, 17042 La Rochelle, France.
authors.forename: Meriem
authors.initials: M
authors.lastname: Kacem
authors.affiliation: Université de La Rochelle, UMR CNRS 7266, LIENSs, Equipe Approches Moléculaires, Environnement-Santé, Département de Biotechnologies, Avenue Michel Crépeau, 17042 La Rochelle, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Poupard
authors.affiliation: Université de La Rochelle, UMR CNRS 7266, LIENSs, Equipe Approches Moléculaires, Environnement-Santé, Département de Biotechnologies, Avenue Michel Crépeau, 17042 La Rochelle, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Bordenave-Juchereau
authors.affiliation: Université de La Rochelle, UMR CNRS 7266, LIENSs, Equipe Approches Moléculaires, Environnement-Santé, Département de Biotechnologies, Avenue Michel Crépeau, 17042 La Rochelle, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Sannier
authors.affiliation: Centre de Biophysique Moléculaire, UPR CNRS 4301, Orléans, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Lamerant-Fayel
authors.affiliation: Centre de Biophysique Moléculaire, UPR CNRS 4301, Orléans, France.
authors.forename: Claudine
authors.initials: C
authors.lastname: Kieda
authors.affiliation: Institut de Recherche en Cancérologie de Montpellier (IRCM), Institut National de la Santé et de la Recherche Médicale (INSERM) U896, Université Montpellier1, Montpellier, France.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Liaudet-Coopman
authors.affiliation: Université de La Rochelle, UMR CNRS 7266, LIENSs, Equipe Approches Moléculaires, Environnement-Santé, Département de Biotechnologies, Avenue Michel Crépeau, 17042 La Rochelle, France.
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Piot
authors.affiliation: Université de La Rochelle, UMR CNRS 7266, LIENSs, Equipe Approches Moléculaires, Environnement-Santé, Département de Biotechnologies, Avenue Michel Crépeau, 17042 La Rochelle, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Maugard
authors.affiliation: Université de La Rochelle, UMR CNRS 7266, LIENSs, Equipe Approches Moléculaires, Environnement-Santé, Département de Biotechnologies, Avenue Michel Crépeau, 17042 La Rochelle, France. Electronic address: ingrid.fruitier@univ-lr.fr.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Fruitier-Arnaudin
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism*; D002402:Cathepsin D / Q000378:metabolism*; D015687:Cell Hypoxia / Q000235:genetics / Q000502:physiology; D002465:Cell Movement / Q000502:physiology; D005260:Female; D006801:Humans; D007700:Kinetics; D061986:MCF-7 Cells
chemical_list: D002402:Cathepsin D
keywords: Acidification; Cathepsin D; Hypoxia; Pro-cathepsin D; Proteolytic activity; Tumor microenvironment