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The anti-apoptotic effect of leukotriene D-4 involves the prevention of caspase 8 activation and Bid cleavage

Wikström, Katarina LU ; Juhas, Maria LU and Sjölander, Anita LU (2003) In Biochemical Journal 371. p.115-124
Abstract
We have shown in a previous study that leukotriene D-4 (LTD4) signalling increases cell survival and proliferation in intestinal epithelial cells [ohd, Wikstrom and Sjolander (2000) Gastroenterology 119, 1007-1018]. This is highly interesting since inflammatory conditions of the bowel are associated with an increased risk of developing colon cancer. The enzyme cyclooxygenase 2 (COX-2) is important in this context since it is upregulated in colon cancer tissues and in tumour cell lines. Treatment with the COX-2-specific inhibitor N-(2-cyclohexyloxy-4-nitrophenyl)methane sulphonamide has been shown previously to cause apoptosis in intestinal epithelial cells. In the present study, we attempted to elucidate the underlying mechanisms and we... (More)
We have shown in a previous study that leukotriene D-4 (LTD4) signalling increases cell survival and proliferation in intestinal epithelial cells [ohd, Wikstrom and Sjolander (2000) Gastroenterology 119, 1007-1018]. This is highly interesting since inflammatory conditions of the bowel are associated with an increased risk of developing colon cancer. The enzyme cyclooxygenase 2 (COX-2) is important in this context since it is upregulated in colon cancer tissues and in tumour cell lines. Treatment with the COX-2-specific inhibitor N-(2-cyclohexyloxy-4-nitrophenyl)methane sulphonamide has been shown previously to cause apoptosis in intestinal epithelial cells. In the present study, we attempted to elucidate the underlying mechanisms and we can now show that a mitochondrial pathway is employed. Inhibition of COX-2 causes release of cytochrome c, as shown by both Western-blot and microscopy studies, and as with apoptosis, this is significantly decreased by LTD4. Since previous studies showed increased Bcl-2 levels on LTD4 stimulation, we further studied apoptotic regulation at the mitochondrial level. From this we could exclude the involvement of the anti-apoptotic protein Bcl-X-L as well as its pro-apoptotic counterpart Bax, since they are not expressed. Furthermore, the activity of the proapoptotic protein Bad (Bcl-2/Bcl-X-L-antagonist, causing cell death) was completely unaffected. However, inhibition of COX-2 caused cleavage of caspase 8 into a 41 kDa fragment associated with activation and caused the appearance of an activated 15 kDa fragment of Bid. This indicates that N-(2-cyclohexyloxy4-nitrophenyl)methane sulphonamide-induced apoptosis is mediated by the activation of caspase 8, via generation of truncated Bid, and thereafter release of cytochrome c. Interestingly, LTD4 not only reverses the effects induced by inhibition of COX-2 but also reduces the apoptotic potential by lowering the basal level of caspase 8 activation and truncated Bid generation. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Bcl-X-1, Bad, cytochrome c, cyclo-oxygenase 2, epithelial cell
in
Biochemical Journal
volume
371
pages
115 - 124
publisher
Portland Press Limited
external identifiers
  • wos:000182177100012
  • pmid:12482325
  • scopus:0037393117
ISSN
0264-6021
DOI
10.1042/BJ20021669
language
English
LU publication?
yes
id
ec816c74-0513-4395-a2c1-7c1e3bfedef4 (old id 313834)
alternative location
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12482325&dopt=Abstract
date added to LUP
2007-09-24 09:05:37
date last changed
2018-01-07 09:10:30
@article{ec816c74-0513-4395-a2c1-7c1e3bfedef4,
  abstract     = {We have shown in a previous study that leukotriene D-4 (LTD4) signalling increases cell survival and proliferation in intestinal epithelial cells [ohd, Wikstrom and Sjolander (2000) Gastroenterology 119, 1007-1018]. This is highly interesting since inflammatory conditions of the bowel are associated with an increased risk of developing colon cancer. The enzyme cyclooxygenase 2 (COX-2) is important in this context since it is upregulated in colon cancer tissues and in tumour cell lines. Treatment with the COX-2-specific inhibitor N-(2-cyclohexyloxy-4-nitrophenyl)methane sulphonamide has been shown previously to cause apoptosis in intestinal epithelial cells. In the present study, we attempted to elucidate the underlying mechanisms and we can now show that a mitochondrial pathway is employed. Inhibition of COX-2 causes release of cytochrome c, as shown by both Western-blot and microscopy studies, and as with apoptosis, this is significantly decreased by LTD4. Since previous studies showed increased Bcl-2 levels on LTD4 stimulation, we further studied apoptotic regulation at the mitochondrial level. From this we could exclude the involvement of the anti-apoptotic protein Bcl-X-L as well as its pro-apoptotic counterpart Bax, since they are not expressed. Furthermore, the activity of the proapoptotic protein Bad (Bcl-2/Bcl-X-L-antagonist, causing cell death) was completely unaffected. However, inhibition of COX-2 caused cleavage of caspase 8 into a 41 kDa fragment associated with activation and caused the appearance of an activated 15 kDa fragment of Bid. This indicates that N-(2-cyclohexyloxy4-nitrophenyl)methane sulphonamide-induced apoptosis is mediated by the activation of caspase 8, via generation of truncated Bid, and thereafter release of cytochrome c. Interestingly, LTD4 not only reverses the effects induced by inhibition of COX-2 but also reduces the apoptotic potential by lowering the basal level of caspase 8 activation and truncated Bid generation.},
  author       = {Wikström, Katarina and Juhas, Maria and Sjölander, Anita},
  issn         = {0264-6021},
  keyword      = {Bcl-X-1,Bad,cytochrome c,cyclo-oxygenase 2,epithelial cell},
  language     = {eng},
  pages        = {115--124},
  publisher    = {Portland Press Limited},
  series       = {Biochemical Journal},
  title        = {The anti-apoptotic effect of leukotriene D-4 involves the prevention of caspase 8 activation and Bid cleavage},
  url          = {http://dx.doi.org/10.1042/BJ20021669},
  volume       = {371},
  year         = {2003},
}