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Involvement of interleukin-1beta-converting enzyme in apoptosis of irradiated retinoblastomas
1Department of Neurosciences, Brain Tumor/Neuro-Oncology Center, The Cleveland Clinic Foundation, Ohio 44195, USA.
Purpose:
To investigate whether interleukin-1beta-converting enzyme (ICE), a mammalian homologue of the Caenorhabditis elegans cell death gene ced-3, is involved in gamma-irradiation-induced apoptosis (programmed cell death) of human retinoblastoma cells.
Methods:
The induction of apoptotic cell death in human retinoblastoma cell lines WERI-Rb-1 and Y79 by gamma-irradiation was determined with a modified 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl tetrazolium bromide colorimetric assay and the DNA-binding fluorochrome bis (benzimide) trihydro-chloride (Hoechst 33258) staining. The change of ICE protein level in tumor cells during apoptosis was determined by immunoblotting assay. Whether the specific tetrapeptide ICE inhibitor Ac-YVAD-CMK affected gamma-irradiation-induced apoptosis in tumor cells was also examined. The effect of ICE overexpression on tumor cells was evaluated by a transient transfection assay using ICE expression vector.
Results:
Gamma-irradiation inhibited the cell viability of WERI-Rb-1 and Y79 cells in a dose-dependent manner and induced apoptosis. The protein level of ICE was remarkably enhanced after the treatment. The apoptotic cell death induced by gamma-irradiation was suppressed by the tetrapeptide ICE inhibitor Ac-YVAD-CMK. Moreover, overexpression of ICE induced apoptosis in tumor cells.
Conclusions:
These findings suggest that ICE may play an important role in gamma-irradiation-induced apoptosis in retinoblastoma cells. Transfer of the ICE gene induces apoptosis in these cells without gamma-irradiation.
Insights
Interleukin-1beta-converting enzyme (ICE) plays a key role in gamma-irradiation-induced apoptosis of retinoblastoma cells. Overexpressing ICE also triggers programmed cell death in these tumor cells.
Area of Science:
- Oncology
- Molecular Biology
- Cell Death Research
Background:
- Retinoblastoma is a pediatric eye cancer.
- Apoptosis, or programmed cell death, is a critical cellular process.
- Interleukin-1beta-converting enzyme (ICE) is a mammalian homologue of a key cell death gene.
Purpose of the Study:
- To investigate the role of ICE in gamma-irradiation-induced apoptosis in human retinoblastoma cells.
- To determine if ICE is a critical mediator of programmed cell death in response to radiation therapy.
Main Methods:
- Assessing cell viability and apoptosis using MTT assays and Hoechst staining.
- Quantifying ICE protein levels via immunoblotting.
- Evaluating the effects of an ICE inhibitor (Ac-YVAD-CMK) and ICE gene overexpression on retinoblastoma cells.
Main Results:
- Gamma-irradiation induced apoptosis in retinoblastoma cell lines (WERI-Rb-1 and Y79) in a dose-dependent manner.
- ICE protein levels significantly increased following gamma-irradiation.
- Inhibition of ICE reduced radiation-induced apoptosis, while ICE overexpression promoted apoptosis.
Conclusions:
- ICE is implicated as an important mediator in gamma-irradiation-induced apoptosis of retinoblastoma cells.
- ICE gene transfer alone can induce apoptosis in retinoblastoma cells, independent of radiation treatment.