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Activation of c‐Jun‐N‐terminal‐kinase is crucial for the induction of a cell cycle arrest in human colon carcinoma cells caused by flurbiprofen enantiomers
Author(s) -
Grösch Sabine,
Tegeder Irmgard,
Schilling Karin,
Maier Thorsten,
Niederberger Ellen,
Geisslinger Gerd
Publication year - 2003
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.02-0919fje
Subject(s) - flurbiprofen , cyclin d1 , cell cycle , apoptosis , kinase , chemistry , cyclin a , western blot , junb , microbiology and biotechnology , cyclin d , cancer research , pharmacology , biology , transcription factor , biochemistry , gene
The unselective cyclooxygenase (COX) inhibitor S‐flurbiprofen and its—in terms of COX‐inhibition—“inactive” enantiomer R‐flurbiprofen have been previously found to inhibit tumor development and growth in various animal models. The underlying mechanisms are unknown. Here, we show that both R‐ and S‐flurbiprofen reduce survival of three colon cancer cell lines, which differ in the expression of COX‐2 (HCT‐15, no COX‐2; Caco‐2, inducible COX‐2; and HT‐29, constitutive COX‐2). The IC 50 for S‐ and R‐flurbiprofen ranged from 250 to 450 µM. Both flurbiprofen enantiomers induced apoptosis in all three cell lines as indicated by DNA‐ and PARP‐cleavage. In addition, R‐ and S‐flurbiprofen caused a G 1 ‐cell cycle block. The latter was associated with an activation of c‐Jun N‐terminal kinase (JNK), an increase of the DNA binding activity of the transcription factor AP‐1 and down‐regulation of cyclin D1 expression. Western blot analysis, as well as supershift experiments, revealed that the AP‐1 activation was associated with a change of AP‐1 composition toward an increase of JunB. The JNK inhibitor SP600125 antagonized R‐ and S‐flurbiprofen‐induced AP‐1 DNA binding, suppression of cyclin D1 expression, and the G 1 ‐cell cycle block. However, JNK inhibition had no effect on flurbiprofen‐induced apoptosis. Hence, the cell cycle arrest is obviously mediated, at least in part, through JNK‐activation, whereas R‐ and S‐flurbiprofen‐induced apoptosis is largely independent of JNK. Although in vitro effects of R‐and S‐flurbiprofen were indistinguishable, only R‐flurbiprofen inhibited HCT‐15 tumor growth in nude mice, suggesting the involvement of additional in vivo targets, which are differently affected by R‐ and S‐flurbiprofen.