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Caspase 8 is deleted or silenced preferentially in childhood neuroblastomas with amplification of MYCN
T Teitz1, T Wei, M B Valentine
1Department of Tumor Cell Biology, St. Jude Children's Research Hospital, 332 N. Lauderdale, Memphis, Tennessee 38101, USA.
Abstract:
Caspase 8 is a cysteine protease regulated in both a death-receptor-dependent and -independent manner during apoptosis. Here, we report that the gene for caspase 8 is frequently inactivated in neuroblastoma, a childhood tumor of the peripheral nervous system. The gene is silenced through DNA methylation as well as through gene deletion. Complete inactivation of CASP8 occurred almost exclusively in neuroblastomas with amplification of the oncogene MYCN. Caspase 8-null neuroblastoma cells were resistant to death receptor- and doxorubicin-mediated apoptosis, deficits that were corrected by programmed expression of the enzyme. Thus, caspase 8 acts as a tumor suppressor in neuroblastomas with amplification of MYCN.
Insights
The gene for caspase 8 (CASP8) is often inactivated in neuroblastoma, a childhood cancer. This inactivation, linked to MYCN amplification, suggests CASP8 acts as a tumor suppressor.
Area of Science:
- Molecular biology
- Cancer research
- Cellular apoptosis
Background:
- Caspase 8 (CASP8) is a cysteine protease crucial for apoptosis.
- Apoptosis regulation is vital in preventing uncontrolled cell proliferation.
- Neuroblastoma is a childhood cancer of the peripheral nervous system.
Purpose of the Study:
- To investigate the role of Caspase 8 inactivation in neuroblastoma.
- To determine the mechanisms of CASP8 gene silencing.
- To assess the functional consequence of CASP8 loss in neuroblastoma development.
Main Methods:
- Analysis of CASP8 gene status (methylation, deletion) in neuroblastoma samples.
- Correlation of CASP8 inactivation with MYCN amplification.
- Functional assays using caspase 8-null neuroblastoma cells to assess apoptosis resistance and correction.
Main Results:
- CASP8 gene is frequently inactivated in neuroblastoma.
- Inactivation occurs via DNA methylation and gene deletion.
- Complete CASP8 inactivation is strongly associated with MYCN amplification.
- Caspase 8-null cells exhibit resistance to apoptosis, which is reversible upon re-expression of the enzyme.
Conclusions:
- Caspase 8 functions as a tumor suppressor in neuroblastoma.
- CASP8 inactivation, particularly in MYCN-amplified tumors, contributes to neuroblastoma pathogenesis.
- Targeting apoptosis pathways may offer therapeutic strategies for neuroblastoma.