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Potentiation of tnf‐mediated cell killing by VP‐16: Relationship to DNA single‐strand break formation
Author(s) -
Branellec Didier,
Markovits Judith,
Chouaib Salem
Publication year - 1990
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.2910460617
Subject(s) - lysis , microbiology and biotechnology , biology , dna , cell , tumor necrosis factor alpha , cytolysis , dna damage , cytotoxicity , biochemistry , immunology , in vitro
Interaction between tumor necrosis factor (TNF) and the DNA topoisomerase II inhibitor, etoposide VP‐16, in cell killing has been studied. To accurately investigate the nature of DNA damage during the cell killing process, experiments were assessed using the highly TNF‐sensitive WEH1164.13 murine fibrosarcoma clone and DNA filter elution methodology. Concomitant treatment of cells with combination of TNF/VP‐16 resulted in marked enhancement of cell lysis. Using the alkaline elution technique, we show that TNF fails to induce DNA single‐strand breaks as compared to those generated by VP‐16. In addition, the potentiating effect of VP‐16 on TNF‐mediated WEH1164.13 cell killing was not associated with an increase in its intrinsic activity with respect to DNA single‐strand break formation. While the 2 phospholipase A2 inhibitors, quinacrine and dexamethasone, were efficient in inhibiting TNF‐mediated cell lysis, only quinacrine was efficient in selectively abrogating the TNF/VP‐16 cell killing pathway. The inhibitory effect of quinacrine on VP‐16/TNF‐mediated cell lysis was accompanied by a marked decrease in VP‐16‐mediated DNA single‐strand break generation. Taken together, our findings suggest that TNF and TNF/VP‐16 treatments may involve different events during cell killing and support the hypothesis that 2 signals are required for optimal induction of cell lysis by the combination of VP‐16/TNF: one signal provided by VP‐16 resulting in topoisomerase II inhibition and subsequent DNA single‐strand break generation, and a second signal involving TNF.