| 2. |
- Laurent-Matha, Valerie, et al.
(författare)
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Proteolysis of cystatin C by cathepsin D in the breast cancer microenvironment
- 2012
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Ingår i: FASEB Journal. - : Wiley. - 1530-6860 .- 0892-6638. ; 26:12, s. 5172-5181
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Tidskriftsartikel (refereegranskat)abstract
- 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.-Laurent-Matha, V., Huesgen, P. F., Masson, O., Derocq, D., Prebois, C., Gary-Bobo, M., Lecaille, F., Rebiere, B., Meurice, G., Orear, C., Hollingsworth, R. E., Abrahamson, M., Lalmanach, G., Overall, C. M., Liaudet-Coopman, E. Proteolysis of cystatin C by cathepsin D in the breast cancer microenvironment. FASEB J. 26, 5172-5181 (2012). www.fasebj.org
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| 3. |
- Nilsson, Cathrine, 1978-
(författare)
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Impact of Lysosomal Function in Cancer and Apoptosis
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Lysosomes, the recycling units of the cell, participate in the signaling pathway to apoptosis, which has stimulated the search for anti-cancer drugs targeting the lysosomal compartment. Lysosomes are, however, often altered in cancer cells. The aim of this thesis was to investigate the involvement of lysosomes during apoptosis in normal and cancer cells. We developed and used flow cytometric methods to measure cytosolic and lysosomal pH in cells. The cytosolic pH of U937 cells decreased, in a caspase-independent way, by 1.4 pH-units during apoptosis. Concomitantly, the lysosomal pH increased from 4.3 to 5.2, suggesting that proton release from lysosomes might be responsible for cytosolic acidification. When studying the lysosomal pH of head and neck squamous cell carcinoma (HNSCC) cell lines and normal oral keratinocytes (NOKs), the pH was significantly increased in three of five HNSCC cell lines, as compared to NOKs. Moreover, high lysosomal pH correlated to low expression of the B subunit of the vacuolar V0/V1-ATPase, a necessary component of the proton pump responsible for lysosomal acidification, and to reduced intrinsic cisplatin sensitivity. Cisplatin-induced apoptosis was, at least partly, dependent on lysosomal cathepsins. When investigating the colony formation ability of the two HNSCC cell lines LK0412 and SqCC/Y1, both were found to give rise to holoclones, indicating the presence of cells with cancer stem cell properties. Holoclone cells from the LK0412 cell line were less sensitive to cisplatin compared to more differentiated paraclone cells. Moreover, we detected differences in intracellular localization of the lysosomal compartment and expression of cathepsins between holo- and paraclone cells.This thesis shows that changes found in the lysosomal compartment of cancer cells, such as alteration of lysosomal pH, might influence the outcome of a drug treatment. In addition, differences in drug sensitivity between subpopulations of tumor cells may affect the outcome of an anticancer therapy.
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