Constitutively active NFkappa B is required for the survival of S-type neuroblastoma.
The NFkappaB transcription factors can both promote cell survival and induce apoptosis depending on cell type and context. Neuroblastoma (NB) cells display two predominant culture phenotypes identified as N- and S-types. Malignant S-type cells express neither high levels of MYCN nor Bcl-2, suggesting that other survival mechanisms are important. We characterized NFkappaB activity in S-type cells and determined its role in their survival. S-type lines (SH-EP1 and SK-N-AS) were treated with pyrrolidine dithiocarbamate (PDTC), a NFkappaB inhibitor, or l-1-tosylamido-2-phenylethyl chloromethyl ketone (TPCK), a serine protease inhibitor that blocks IkappaBalpha degradation. Both agents induced cell death, suggesting that constitutive NFkappaB activity is required for survival. The transient expression of a super-repressor IkappaBalpha mutant killed S-type cells. The inhibition of NFkappaB produced an apoptotic response characterized by the collapse of the mitochondrial transmembrane electrochemical gradient, caspase-9 activation, and apoptotic DNA changes. Constitutive NFkappaB DNA binding activity specifically involving p65 and p50 was demonstrated in S- but not N-type cells by electromobility supershift and gene reporter assays. This study demonstrates a role for NFkappaB in the survival of S-type NB tumor cells and suggests that NFkappaB activity and function differ according to NB tumor cell phenotype.
Department of Pediatrics, University of Michigan, Ann Arbor 48109, USA.
Xin
X
Bian
Anthony W
AW
Opipari
Anthony B
AB
Ratanaproeksa
Anthony E
AE
Boitano
Peter C
PC
Lucas
Valerie P
VP
Castle
D017209:Apoptosis; D002470:Cell Survival; D006801:Humans; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000502:physiology*; D009447:Neuroblastoma / Q000473:pathology*; D011392:Proline / Q000031:analogs & derivatives* / Q000494:pharmacology; D013859:Thiocarbamates / Q000494:pharmacology; D014108:Tosylphenylalanyl Chloromethyl Ketone / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D016328:NF-kappa B; D013859:Thiocarbamates; C066229:prolinedithiocarbamate; D014108:Tosylphenylalanyl Chloromethyl Ketone; D011392:Proline