The adenylate cyclase activator forskolin partially protects L929 cells against tumour necrosis factor-alpha-mediated cytotoxicity via a cAMP-independent mechanism

Cytokine. 2002 Sep 7;19(5):250-8.


Recent reports indicate that cAMP-elevating agents can protect against cell death induced by many stimuli, including tumour necrosis factor-alpha (TNF-alpha). We investigated the ability of cAMP-elevating agents to modulate TNF-alpha-mediated cytotoxicity in L929 cells. Using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide) reduction assay and a DNA fragmentation assay as indicators of cell survival, we have shown that forskolin confers partial protection against TNF-alpha-mediated cytotoxicity and inhibits TNF-alpha-induced internucleosomal DNA fragmentation in L929 cells. The protection conferred by forskolin is cAMP-independent since 1,9-dideoxyforskolin (an adenylate cyclase-inactive analog) also protected against TNF-alpha, while both dibutyryl-cAMP and the cAMP-phosphodiesterase inhibitor theophylline were not protective. This is the first example (that we know of) of cAMP-independent cytoprotection by forskolin. We conclude that forskolin acts in a cAMP-independent manner, potentially at a site upstream of caspase-3 activation, to protect against TNF-alpha-mediated cytotoxicity in L929 cells, and that cAMP elevation, in general, does not confer protection against TNF-alpha-induced death in L929 cells. In addition, we observed that Cyclosporin A, a mitochondrial permeability transition (MPT) inhibitor, protected L929 cells against TNF-alpha, underlining the importance of mitochondria in the cytotoxic process induced by TNF-alpha in L929 cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenylyl Cyclases / metabolism
  • Cell Death / drug effects
  • Cell Line
  • Cell Membrane Permeability / drug effects
  • Colforsin / pharmacology*
  • Cyclic AMP / metabolism*
  • Cyclosporine / pharmacology
  • DNA Fragmentation / drug effects
  • Humans
  • Pentoxifylline / pharmacology
  • Theophylline / pharmacology
  • Time Factors
  • Tumor Necrosis Factor-alpha / antagonists & inhibitors*
  • Tumor Necrosis Factor-alpha / pharmacology


  • Tumor Necrosis Factor-alpha
  • Colforsin
  • Cyclosporine
  • Theophylline
  • Cyclic AMP
  • Adenylyl Cyclases
  • Pentoxifylline