Involvement of interleukin-1beta-converting enzyme in apoptosis of irradiated retinoblastomas.
OBJECTIVE
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.
Kondo
Y
Y
Department of Neurosciences, Brain Tumor/Neuro-Oncology Center, The Cleveland Clinic Foundation, Ohio 44195, USA.
Liu
J
J
Haqqi
T
T
Barna
B P
BP
Kondo
S
S
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects*; D006690:Bisbenzimidazole; D002470:Cell Survival; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004273:DNA, Neoplasm / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D010450:Endopeptidases / Q000378:metabolism*; D005456:Fluorescent Dyes; D005720:Gamma Rays; D006801:Humans; D015151:Immunoblotting; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D019572:Retinal Neoplasms / Q000201:enzymology* / Q000473:pathology / Q000532:radiotherapy; D012175:Retinoblastoma / Q000201:enzymology* / Q000473:pathology / Q000532:radiotherapy; D014162:Transfection; D014407:Tumor Cells, Cultured; D053148:Caspase 3
D000590:Amino Acid Chloromethyl Ketones; D006690:Bisbenzimidazole; D015853:Cysteine Proteinase Inhibitors; D004273:DNA, Neoplasm; D010450:Endopeptidases; D005456:Fluorescent Dyes; D009419:Nerve Tissue Proteins; C098738:N-acetyl-tyrosyl-valyl-alanyl-aspartyl chloromethyl ketone; C505410:Casp3 protein, rat; D053148:Caspase 3