title: Enzymatically active cathepsin D sensitizes breast carcinoma cells to TRAIL.
abstract: Cathepsin D (CD), a ubiquitously expressed lysosomal aspartic protease, is upregulated in human breast carcinoma and many other tumor types. CD has been repeatedly reported to act as key mediator of apoptosis induced by various chemotherapeutics. However, there is still controversy over the role of enzymatic/proteolytic versus protein-protein interaction activities of CD in apoptotic signaling. The elucidation of molecular mechanism responsible for the effect of CD in the chemotherapy-induced cell death is crucial for development of an appropriate strategy to target this protease in cancer treatment. Therefore, the objective of this study was to investigate the molecular mechanism behind the CD-mediated regulation of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced cell death. For this purpose, MDA-MB-231 breast carcinoma cells with an increased level of wt CD (CD) or mutant enzymatically inactive CD (ΔCD) were subjected to TRAIL and the frequency of apoptosis was determined. Our results show that CD facilitates the TRAIL-induced apoptosis of MDA-MB-231 breast cancer cells in enzymatic activity-dependent manner. Moreover, the importance of endosomal/lysosomal acidification in this process was documented. Analysis of the potential substrates specifically cleaved by CD during the TRAIL-induced apoptosis confirmed caspase-8 and Bid proteins as the CD targets. Moreover, in search for protein regulators of apoptosis that can be cleaved by CD at physiologically relevant pH, we identified the Bcl-2 protein as a suitable candidate. The modulatory role of CD in cell response to TRAIL was also confirmed in another breast cancer cell line SKBR3. These experiments identified the CD enzymatic activity as a new factor affecting sensitivity of breast cancer cells to TRAIL.
authors: Department of Experimental Biology, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.|International Clinical Research Center, Center for Biological and Cellular Engineering, St. Anne's, University Hospital Brno, Pekarska 53, 656 91, Brno, Czech Republic.
authors: Blanka
authors: B
authors: Jancekova
authors: Department of Experimental Biology, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.|Masaryk Memorial Cancer Institute, RECAMO, Zluty kopec 7, 656 53, Brno, Czech Republic.
authors: Eva
authors: E
authors: Ondrouskova
authors: Department of Experimental Biology, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.|International Clinical Research Center, Center for Biological and Cellular Engineering, St. Anne's, University Hospital Brno, Pekarska 53, 656 91, Brno, Czech Republic.
authors: Lucia
authors: L
authors: Knopfova
authors: Department of Experimental Biology, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.
authors: Jan
authors: J
authors: Smarda
authors: Department of Experimental Biology, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic. pbenes@sci.muni.cz.|International Clinical Research Center, Center for Biological and Cellular Engineering, St. Anne's, University Hospital Brno, Pekarska 53, 656 91, Brno, Czech Republic. pbenes@sci.muni.cz.
authors: Petr
authors: P
authors: Benes
mesh_terms: D000230:Adenocarcinoma / Q000201:enzymology / Q000473:pathology*; D017209:Apoptosis / Q000187:drug effects; D051023:BH3 Interacting Domain Death Agonist Protein / Q000378:metabolism; D001943:Breast Neoplasms / Q000201:enzymology / Q000473:pathology*; D053181:Caspase 8 / Q000378:metabolism; D002402:Cathepsin D / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm; D011992:Endosomes / Q000378:metabolism; D004789:Enzyme Activation; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008247:Lysosomes / Q000378:metabolism; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000494:pharmacology*; D014162:Transfection
chemical_list: D051023:BH3 Interacting Domain Death Agonist Protein; C494814:BID protein, human; D009363:Neoplasm Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; C505530:CASP8 protein, human; D053181:Caspase 8; C533922:CTSD protein, human; D002402:Cathepsin D
keywords: Apoptosis; Bcl-2; Breast cancer; Caspases; Cathepsin D; TRAIL