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Zn ++ inhibits both tumor necrosis factor‐mediated DNA fragmentation and cytolysis
Author(s) -
Flieger Dimitri,
Riethmüller Gert,
ZieglerHeitbrock H. W. L.
Publication year - 1989
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.2910440221
Subject(s) - cytolysis , tumor necrosis factor alpha , trypan blue , lysis , dna fragmentation , fragmentation (computing) , microbiology and biotechnology , programmed cell death , dna , necrosis , cell , divalent , chemistry , cytoplasm , cytotoxicity , biology , biochemistry , apoptosis , immunology , in vitro , ecology , genetics , organic chemistry
The cellular events involved in direct tumor‐cell destruction by tumor necrosis factor (TNF) are still incompletely understood, but a role of endonucleases has been suggested. In the present study we have analyzed in detail the effect of Zn ++ , an inhibitor of endonucleases, on TNF‐mediated DNA‐fragmentation and on cytolysis in Actinomycin‐D‐pre‐treated WEH1164‐S cells. Beginning 2 hr after addition of TNF, a rapid degradation of cellular DNA is observed, as evidenced by release of 3 H‐Thymidine (TdR) label from nuclei into cytoplasm. TNF‐mediated lysis of WEH1164‐S cells begins at 3 hr and reaches plateau levels at 7 hr. Addition of Zn ++ to TNF‐treated WEH1164 cells completely abrogates DNA fragmentation at 1m M . Of greater importance is the fact that Zn ++ treatment also completely blocks TNF‐mediated cytolysis of the target cells. Concentrations between 0.1 and I m M ZnSO 4 prevent cell death, as assessed by chromium‐release and Trypan blue dye exclusion. In addition, ZnCI 2 , but not other divalent cations like CaCI 2 , MgSO 4 and CuSO 4 in the same concentration range, prevents cell death as well, demonstrating that the effect in fact is mediated by Zn ++ . Zn ++ added 2 hr after TNF treatment, still effectively inhibits cell lysis, indicating that it acts at a late stage after binding of TNF to its receptor. Our data suggest that activation of endonucleases is not an accompanying effect but an essential step in TNF‐mediated tumor‐cell destruction.