as soon as  is submitted to ZB.
		
    
        
        Binding of heat shock protein 70 to extracellular phosphatidylserine promotes killing of normoxic and hypoxic tumor cells.
    
        
        FASEB J. 23, 2467-2477 (2009)
    
    
    
	    Hypoxia is well known to limit curability of tumors by ionizing radiation. Here, we show that hypoxia treatment of tumor cells causes coexpression of heat shock protein 70 (Hsp70) and phosphatidylserine (PS) on the cell surface. Colocalization of Hsp70 and PS, as determined by confocal microscopy, also occurs when exogenous FITC-labeled Hsp70 protein is added to normoxic and hypoxic tumor cells. Moreover, the interaction of Hsp70 with PS was demonstrated in artificial unilamellar phosphatidylcholine/ phosphatidylserine (PC/PS) liposomes at the physiological ratio of 8/2. Indeed, the Hsp70-liposome interaction gradually increased with elevating PS molar ratios (8/2 > or = 7/3 < 5/5 < 4/6 < 3/7 < 2/8). In contrast, only a weak Hsp70 interaction was detected in phosphatidylcholine/phosphatidylglycerol (PC/PG) liposomes, thus demonstrating that the interaction was not a charge-related effect. The interaction of Hsp70 with surface PS significantly reduces clonogenic cell survival in normoxic (EC(50) of Hsp70=85 microg/ml) and hypoxic (EC(50) of Hsp70=55 microg/ml) tumor cells. The radiation-induced tumor cell killing was significantly enhanced by the addition of Hsp70 protein (50 microg/ml). Since apoptosis was not significantly enhanced in normoxic and hypoxic tumor cells by the addition of Hsp70, we hypothesize that the Hsp70 protein-induced reduction in clonogenic cell survival might be through necrosis rather than apoptosis.
	
	
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        Publication type
        Article: Journal article
    
 
    
        Document type
        Scientific Article
    
 
     
    
    
        Keywords
        nonapoptotic tumor cell death; stress proteins; ionizing radiation; cancer therapy; heat-shock proteins; natural-killer-cells; immune-response; molecular chaperones; transcription factor; mammalian-cells; stress-proteins; in-vitro; hsp70; cancer
    
 
     
    
    
        Language
        english
    
 
    
        Publication Year
        2009
    
 
     
    
        HGF-reported in Year
        0
    
 
    
    
        ISSN (print) / ISBN
        0892-6638
    
 
    
        e-ISSN
        1530-6860
    
 
    
     
     
	     
	 
	 
    
        Journal
        FASEB Journal
    
 
	
    
        Quellenangaben
        
	    Volume: 23,  
	    Issue: 8,  
	    Pages: 2467-2477 
	    
	    
	
    
 
    
         
        
            Publisher
            Wiley
        
 
        
            Publishing Place
            Bethesda, Md.
        
 
	
         
         
         
         
         
	
         
         
         
    
         
         
         
         
         
         
         
    
        Reviewing status
        Peer reviewed
    
 
    
        Institute(s)
        CCG Innate Immunity in Tumor Biology (PATH-KTB)
    
 
    
        POF-Topic(s)
        30504 - Mechanisms of Genetic and Environmental Influences on Health and Disease
    
 
     
    
        PSP Element(s)
        G-521400-001
    
 
     
     	
    
        PubMed ID
        19289606
    
    
    
        Scopus ID
        68849112162
    
    
        Erfassungsdatum
        2009-09-03