Proteolysis of cystatin C by cathepsin D in the breast cancer microenvironment.
The aspartic protease cathepsin D, a poor prognostic indicator of breast cancer, is abundantly secreted as procathepsin D by human breast cancer cells and self-activates at low pH in vitro, giving rise to catalytically active cathepsin D. Due to a lower extracellular pH in tumor microenvironments compared to normal tissues, cathepsin D may cleave pathophysiological substrates contributing to cancer progression. Here, we show by yeast 2-hybrid and degradomics analyses that cystatin C, the most potent natural secreted inhibitor of cysteine cathepsins, both binds to and is a substrate of extracellular procathepsin D. The amount of cystatin C in the extracellular environment is reduced in the secretome of mouse embryonic fibroblasts stably transfected with human cathepsin D. Cathepsin D extensively cleaved cystatin C in vitro at low pH. Cathepsin D secreted by breast cancer cells also processed cystatin C at the pericellular pH of tumors and so enhancing extracellular proteolytic activity of cysteine cathepsins. Thus, tumor derived cathepsin D assists breast cancer progression by reducing cystatin C activity, which, in turn, enhances cysteine cathepsin proteolytic activity, revealing a new link between protease classes in the protease web.
Institut National de la Santé et de la Recherche Médicale (INSERM) U896, Université Montpellier1, Montpellier, France.
Valérie
V
Laurent-Matha
Pitter F
PF
Huesgen
Olivier
O
Masson
Danielle
D
Derocq
Christine
C
Prébois
Magali
M
Gary-Bobo
Fabien
F
Lecaille
Bertrand
B
Rebière
Guillaume
G
Meurice
Cédric
C
Oréar
Robert E
RE
Hollingsworth
Magnus
M
Abrahamson
Gilles
G
Lalmanach
Christopher M
CM
Overall
Emmanuelle
E
Liaudet-Coopman
D000595:Amino Acid Sequence; D000818:Animals; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002402:Cathepsin D / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D055316:Cystatin C / Q000235:genetics / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000166:cytology; D004792:Enzyme Precursors / Q000235:genetics / Q000378:metabolism; D005110:Extracellular Space / Q000378:metabolism; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015151:Immunoblotting; D061986:MCF-7 Cells; D051379:Mice; D018345:Mice, Knockout; D008954:Models, Biological; D008969:Molecular Sequence Data; D011485:Protein Binding; D059748:Proteolysis; D034622:RNA Interference; D059016:Tumor Microenvironment; D020798:Two-Hybrid System Techniques
D055316:Cystatin C; D004792:Enzyme Precursors; C058345:procathepsin D; D002402:Cathepsin D