Constitutive nuclear factor-kappaB activity is crucial for human retinoblastoma cell viability.
Retinoblastoma (Rb) is the most common intraocular malignancy of childhood. Although systemic and intrathecal chemotherapy with local and cranial radiotherapy have improved overall survival, the prognosis for patients with central nervous system involvement is still poor. We investigated the role of the transcription factor nuclear factor (NF)-kappaB, which promotes cell survival in several other models, in the pathophysiology of Rb. The human Rb cell lines Y79 and WERI-Rb1 were treated with the cell permeable peptide SN50, that specifically inhibits the transcriptional activity of NF-kappaB by blocking its translocation into the nucleus. We found that NF-kappaB inhibition up-regulated Bax; down-regulated the anti-apoptotic proteins Bcl-2, A1, and cIAP-2; and induced loss of the mitochondrial transmembrane potential and caspase-independent, calpain-dependent apoptosis in Rb cells. Inhibition of the p38 kinase sensitized cells to SN50-induced cell death, whereas insulin-like growth factor-1 activated NF-kappaB and attenuated the proapoptotic effect of SN50. Finally, NF-kappaB inhibition sensitized Rb cells to doxorubicin. In conclusion, inhibition of NF-kappaB activity in Rb cells leads to loss of mitochondrial transmembrane potential and caspase-independent, calpain-dependent apoptosis. Therapeutic strategies targeting NF-kappaB could be beneficial in the clinical management of Rb, either alone or in combination with conventional chemotherapy.
Poulaki
Vassiliki
V
Retina Research and Angiogenesis Laboratory, Massachusetts Eye and Ear Infirmary, Harvard Medical School, 325 Cambridge Street, Boston, MA 02114, USA. poulakiv@hotmail.com
Mitsiades
Constantine S
CS
Joussen
Antonia M
AM
Lappas
Alexandra
A
Kirchhof
Bernd
B
Mitsiades
Nicholas
N
D000970:Antineoplastic Agents / Q000378:metabolism; D017209:Apoptosis / Q000502:physiology; D002154:Calpain / Q000037:antagonists & inhibitors; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D002470:Cell Survival; D004247:DNA / Q000378:metabolism; D004151:Dipeptides / Q000378:metabolism; D004317:Doxorubicin / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000378:metabolism; D006801:Humans; D007093:Imidazoles / Q000378:metabolism; D020287:In Situ Nick-End Labeling; D008564:Membrane Potentials / Q000502:physiology; D008928:Mitochondria / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D016376:Oligonucleotides, Antisense / Q000235:genetics / Q000378:metabolism; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D012175:Retinoblastoma / Q000378:metabolism* / Q000473:pathology; D014407:Tumor Cells, Cultured; D048051:p38 Mitogen-Activated Protein Kinases
D000970:Antineoplastic Agents; D004151:Dipeptides; D004791:Enzyme Inhibitors; D007093:Imidazoles; D016328:NF-kappa B; D016376:Oligonucleotides, Antisense; D010455:Peptides; D019253:Proto-Oncogene Proteins c-bcl-2; C118258:SN50 peptide; C071482:calpeptin; D004317:Doxorubicin; D004247:DNA; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C505407:CASP3 protein, human; D002154:Calpain; D053148:Caspase 3; D020169:Caspases; C408604:2-(4-nitrophenyl)-4-(4-fluorophenyl)-5-(4-pyridinyl)-1H-imidazole