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.
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 IC50 for S- and R-flurbiprofen ranged from 250 to 450 microM. 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 G1-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 G1-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.
Grösch
Sabine
S
pharmazentrum frankfurt, Institut für Klinische Pharmakologie, Klinikum der Johann Wolfgang Goethe Universität, Theodor Stern Kai 7, 60590 Frankfurt/Main, Germany. groesch@em.uni-frankfurt.de
Tegeder
Irmgard
I
Schilling
Karin
K
Maier
Thorsten J
TJ
Niederberger
Ellen
E
Geisslinger
Gerd
G
D000818:Animals; D016588:Anticarcinogenic Agents / Q000737:chemistry / Q000494:pharmacology*; D017209:Apoptosis; D018938:Caco-2 Cells; D002277:Carcinoma / Q000201:enzymology* / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins / Q000378:metabolism; D002455:Cell Division; D002470:Cell Survival / Q000187:drug effects; D003110:Colonic Neoplasms / Q000201:enzymology* / Q000378:metabolism; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004789:Enzyme Activation; D005480:Flurbiprofen / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D007536:Isomerism; D048031:JNK Mitogen-Activated Protein Kinases; D020935:MAP Kinase Signaling System; D051379:Mice; D008819:Mice, Nude; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008954:Models, Biological; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014407:Tumor Cells, Cultured
D016588:Anticarcinogenic Agents; D018797:Cell Cycle Proteins; D016861:Cyclooxygenase Inhibitors; D018808:Transcription Factor AP-1; D005480:Flurbiprofen; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases