A link between benzyl isothiocyanate-induced cell cycle arrest and apoptosis: involvement of mitogen-activated protein kinases in the Bcl-2 phosphorylation.
In the present study, we clarified the molecular mechanism underlying the relationship between benzyl isothiocyanate (BITC)-induced cell cycle arrest and apoptosis and the involvement of mitogen-activated protein kinases (MAPKs). The exposure of Jurkat human T-cell leukemia cells to BITC resulted in the inhibition of the G(2)-M progression that coincided with the apoptosis induction. The experiment using the phase-specific synchronized cells demonstrated that the G(2)-M phase-arrested cells are more sensitive to undergoing apoptotic stimulation by BITC than the cells in other phases. We also confirmed that BITC activated c-Jun N-terminal kinase (JNK) and p38 MAPK, but not extracellular signal-regulated kinase, at the concentration required for apoptosis induction. An experiment using a JNK-specific inhibitor SP600125 or a p38 MAPK inhibitor SB202190 indicated that BITC-induced apoptosis might be regulated by the activation of these two kinases. Conversely, BITC is likely to confine the Jurkat cells in the G(2)-M phase mainly through the p38 MAPK pathway because only the p38 MAPK inhibitor significantly attenuated the accumulation of inactive phosphorylated Cdc2 protein and the G(2)-M-arrested cell numbers. We reported here for the first time that the antiapoptotic Bcl-2 protein was phosphorylated by the BITC treatment without significant alteration of the Bcl-2 total protein amount. This was abrogated by a JNK specific inhibitor SP600125 at the concentration required for specific inhibition of the c-Jun phosphorylation. Moreover, the spontaneous phosphorylation of antiapoptotic Bcl-2 in the G(2)-M synchronized cells was enhanced synergistically by the BITC treatment. Involvement of the MAPK activation in the Bcl-2 phosphorylation and apoptosis induction also was observed in HL-60 and HeLa cells. Thus, we identified the phosphorylated Bcl-2 as a key molecule linking the p38 MAPK-dependent cell cycle arrest with the JNK activation by BITC.
Miyoshi
Noriyuki
N
Laboratory of Food and Biodynamics, Nagoya University Graduate School of Bioagricultural Sciences, Nagoya 464-8601, Japan.
Uchida
Koji
K
Osawa
Toshihiko
T
Nakamura
Yoshimasa
Y
D017209:Apoptosis / Q000187:drug effects*; D016203:CDC2 Protein Kinase / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018922:HL-60 Cells; D006367:HeLa Cells; D006801:Humans; D017879:Isothiocyanates / Q000494:pharmacology*; D048031:JNK Mitogen-Activated Protein Kinases; D019169:Jurkat Cells; D048670:MAP Kinase Kinase 4; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D015398:Signal Transduction; D048051:p38 Mitogen-Activated Protein Kinases
D004791:Enzyme Inhibitors; D017879:Isothiocyanates; D019253:Proto-Oncogene Proteins c-bcl-2; C031403:benzyl isothiocyanate; D016203:CDC2 Protein Kinase; D048031:JNK Mitogen-Activated Protein Kinases; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases