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Signaling and function of caspase and c-jun N-terminal kinase in cisplatin-induced apoptosis
Myoung-Sook Koo1, Young-Guen Kwo, Joon-Hong Park
1Vascular System Research Center, Kangwon National University, Chunchon, Korea.
Abstract:
Caspases and c-Jun N-terminal kinase (JNK) are activated in tumor cells during induction of apoptosis. We investigated the signaling cascade and function of these enzymes in cisplatin-induced apoptosis. Treatment of Jurkat T-cells with cisplatin induced cell death with DNA fragmentation and activation of caspase and JNK. Bcl-2 overexpression suppressed activation of both enzymes, whereas p35 and CrmA inhibited only the DEVDase (caspase-3-like) activity, indicating that the activation of these enzymes may be differentially regulated. Cisplatin induced apoptosis with the cytochrome c release and caspase-3 activation in both wild-type and caspase-8-deficient JB-6 cells, while the Fas antibody induced these apoptotic events only in wild-type cells. This indicates that caspase-8 activation is required for Fas-mediated apoptosis, but not cisplatin-induced cell death. On the other hand, cisplatin induced the JNK activation in both the wild-type and JB-6 cells, and the caspase-3 inhibitor Z-DEVD-fmk did not inhibit this activation. The JNK overexpression resulted in a higher JNK activity, AP-1 DNA binding activity, and metallothionein expression than the empty vector-transfected cells following cisplatin treatment. It also partially protected the cells from cisplatin-induced apoptosis by decreasing DEVDase activity. These data suggest that the cisplatin-induced apoptotic signal is initiated by the caspase-8-independent cytochrome c release, and the JNK activation protects cells from cisplatin-induced apoptosis via the metallothionein expression.
Insights
Cisplatin induces apoptosis via caspase-8-independent pathways, activating both caspases and c-Jun N-terminal kinase (JNK). JNK activation protects cells from cisplatin-induced apoptosis by upregulating metallothionein expression.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Caspases and c-Jun N-terminal kinase (JNK) are key mediators of apoptosis.
- Understanding their roles in chemotherapy-induced cell death is crucial for cancer treatment.
Purpose of the Study:
- To investigate the signaling cascade and functional roles of caspases and JNK in cisplatin-induced apoptosis.
- To elucidate the differential regulation and specific contributions of these enzymes to cell death pathways.
Main Methods:
- Treatment of Jurkat T-cells and JB-6 cells (wild-type and caspase-8-deficient) with cisplatin.
- Assessment of apoptosis markers (DNA fragmentation, cytochrome c release) and enzyme activities (caspase, JNK).
- Manipulation of gene expression (Bcl-2 overexpression, p35/CrmA inhibition, JNK overexpression) to study regulatory mechanisms.
Main Results:
- Cisplatin induced apoptosis, DNA fragmentation, and activation of caspase and JNK in Jurkat T-cells.
- Bcl-2 overexpression suppressed both caspase and JNK activation; p35 and CrmA selectively inhibited caspase-3-like activity.
- Cisplatin-induced apoptosis involved caspase-8-independent cytochrome c release and JNK activation, while Fas-mediated apoptosis required caspase-8.
Conclusions:
- Cisplatin-induced apoptosis is initiated by caspase-8-independent cytochrome c release.
- JNK activation, independent of caspase-3, plays a protective role against cisplatin-induced apoptosis, potentially through metallothionein expression.