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Internalization of cystatin C in human cell lines.

Ekström, Ulf LU ; Wallin, Hanna LU ; Lorenzo, Julia; Holmqvist, Bo LU ; Abrahamson, Magnus LU and Avilés, Francesc X (2008) In The FEBS Journal Aug 9. p.4571-4582
Abstract
Altered protease activity is considered important for tumour invasion and metastasis, processes in which the cysteine proteases cathepsin B and L are involved. Their natural inhibitor cystatin C is a secreted protein, suggesting that it functions to control extracellular protease activity. Because cystatins added to cell cultures can inhibit polio, herpes simplex and coronavirus replication, which are intracellular processes, the internalization and intracellular regulation of cysteine proteases by cystatin C should be considered. The extension, mechanism and biological importance of this hypothetical process are unknown. We investigated whether internalization of cystatin C occurs in a set of human cell lines. Demonstrated by flow... (More)
Altered protease activity is considered important for tumour invasion and metastasis, processes in which the cysteine proteases cathepsin B and L are involved. Their natural inhibitor cystatin C is a secreted protein, suggesting that it functions to control extracellular protease activity. Because cystatins added to cell cultures can inhibit polio, herpes simplex and coronavirus replication, which are intracellular processes, the internalization and intracellular regulation of cysteine proteases by cystatin C should be considered. The extension, mechanism and biological importance of this hypothetical process are unknown. We investigated whether internalization of cystatin C occurs in a set of human cell lines. Demonstrated by flow cytometry and confocal microscopy, A-431, MCF-7, MDA-MB-453, MDA-MB-468 and Capan-1 cells internalized fluorophore-conjugated cystatin C when exposed to physiological concentrations (1 mum). During cystatin C incubation, intracellular cystatin C increased after 5 min and accumulated for at least 6 h, reaching four to six times the baseline level. Western blotting showed that the internalized inhibitor was not degraded. It was functionally intact and extracts of cells exposed to cystatin C showed a higher capacity to inhibit papain and cathepsin B than control cells (decrease in enzyme activity of 34% and 37%, respectively). The uptake of labelled cystatin C was inhibited by unlabelled inhibitor, suggesting a specific pathway for the internalization. We conclude that the cysteine protease inhibitor cystatin C is internalized in significant quantities in various cancer cell lines. This is a potentially important physiological phenomenon not previously described for this group of inhibitors. (Less)
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author
organization
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type
Contribution to journal
publication status
published
subject
in
The FEBS Journal
volume
Aug 9
pages
4571 - 4582
publisher
Wiley-Blackwell
external identifiers
  • WOS:000258729100013
  • PMID:18699780
  • Scopus:50849110155
ISSN
1742-464X
DOI
10.1111/j.1742-4658.2008.06600.x
language
English
LU publication?
yes
id
ae1fea72-2164-4be2-92bf-de56bab7e798 (old id 1223249)
alternative location
http://www.ncbi.nlm.nih.gov/pubmed/18699780?dopt=Abstract
date added to LUP
2008-09-02 13:31:55
date last changed
2017-01-01 07:42:06
@article{ae1fea72-2164-4be2-92bf-de56bab7e798,
  abstract     = {Altered protease activity is considered important for tumour invasion and metastasis, processes in which the cysteine proteases cathepsin B and L are involved. Their natural inhibitor cystatin C is a secreted protein, suggesting that it functions to control extracellular protease activity. Because cystatins added to cell cultures can inhibit polio, herpes simplex and coronavirus replication, which are intracellular processes, the internalization and intracellular regulation of cysteine proteases by cystatin C should be considered. The extension, mechanism and biological importance of this hypothetical process are unknown. We investigated whether internalization of cystatin C occurs in a set of human cell lines. Demonstrated by flow cytometry and confocal microscopy, A-431, MCF-7, MDA-MB-453, MDA-MB-468 and Capan-1 cells internalized fluorophore-conjugated cystatin C when exposed to physiological concentrations (1 mum). During cystatin C incubation, intracellular cystatin C increased after 5 min and accumulated for at least 6 h, reaching four to six times the baseline level. Western blotting showed that the internalized inhibitor was not degraded. It was functionally intact and extracts of cells exposed to cystatin C showed a higher capacity to inhibit papain and cathepsin B than control cells (decrease in enzyme activity of 34% and 37%, respectively). The uptake of labelled cystatin C was inhibited by unlabelled inhibitor, suggesting a specific pathway for the internalization. We conclude that the cysteine protease inhibitor cystatin C is internalized in significant quantities in various cancer cell lines. This is a potentially important physiological phenomenon not previously described for this group of inhibitors.},
  author       = {Ekström, Ulf and Wallin, Hanna and Lorenzo, Julia and Holmqvist, Bo and Abrahamson, Magnus and Avilés, Francesc X},
  issn         = {1742-464X},
  language     = {eng},
  pages        = {4571--4582},
  publisher    = {Wiley-Blackwell},
  series       = {The FEBS Journal},
  title        = {Internalization of cystatin C in human cell lines.},
  url          = {http://dx.doi.org/10.1111/j.1742-4658.2008.06600.x},
  volume       = {Aug 9},
  year         = {2008},
}