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. 1995 Jun 15;10(12):2297-305.

Bcl-x and Bcl-2 inhibit TNF and Fas-induced apoptosis and activation of phospholipase A2 in breast carcinoma cells

M Jäättelä  1 , M Benedict, M Tewari, J A Shayman, V M Dixit
Affiliations
  • PMID: 7540278

Bcl-x and Bcl-2 inhibit TNF and Fas-induced apoptosis and activation of phospholipase A2 in breast carcinoma cells

M Jäättelä et al. Oncogene. .

Abstract

Tumor necrosis factor (TNF) induces cel death in several tumor cell lines by undefined mechanisms. Using a cDNA expression cloning strategy we identified two cDNAs that completely inhibit the TNF-induced death pathway in MCF7 breast carcinoma cells. These cDNAs encoded for Bcl-2 and Bcl-x. To compare the cytotoxic signal transduction pathway induced by the TNF receptor versus that induced by Fas, we transfected MCF7 cells with a Fas expression construct. The resulting cell line, MCF-Fas, was highly sensitive to cytotoxicity induced by TNF or anti-Fas. Expression of either bcl-2 or bcl-x in these cells rendered them completely resistant to lysis induced by either TNF or Fas. Interestingly, exposure of MCF-Fas cells to anti-Fas or TNF induced activation of phospholipase A2 (PLA2), while only TNF activated NF-kappa B. Activation of PLA2 was completely blocked whereas activation of NF-kappa B was unaffected by overexpression of either bcl-x or bcl-2. Moreover, PLA2-inhibitors, quinacrine and dexamethasone, partially inhibited cytotoxicity induced by either TNF or anti-Fas. These data suggest an involvement of PLA2 in both TNF- and Fas-mediated cytotoxicity and a novel mechanism of action for bcl-2 and bcl-x, i.e. inhibition of arachidonic acid metabolism, by which they may, in addition of apoptosis, modulate inflammation.

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