PKC alpha phosphorylates cytosolic NF-kappaB/p65 and PKC delta delays nuclear translocation of NF-kappaB/p65 in U1242 glioblastoma cells.
OBJECTIVE
Protein kinase-C (PKC) and NF-kappaB are involved in cell survival, proliferation, migration and radioresistance in glioblastoma multiforme (GBM). We sought to determine the interaction between PKC and NF-kappaB pathways.


METHODS
The activation of NF-kappaB by PKC alpha and PKC delta was assessed by Western blotting after the stimulation with Phorbol 12- Myristate 13-Acetate (PMA). Gene silencing of PKC alpha , PKC delta and NFkappaB/ p65 with siRNA interference was utilized to evaluate their roles in NFkB activation and cell proliferation.


RESULTS
PMA induced the phosphorylation of NF-kappaB/p65 by PKC alpha. Gene silencing with siRNA against NF-kappaB/p65 inhibited [3H]-thymidine incorporation in U1242 GBM cells. PKC delta decelerated the nuclear translocation of activated NF-kappaB/p65 up to 4 hours after the stimulation. PMA induced death was not observed in PKC delta silenced cells where activated NF-kappaB/p65 was located immediately in the nucleus.


CONCLUSIONS
NF-kappaB/p65 is pro-survival and proliferative factor in U1242 GBM cells. PKC alpha is needed to phosphorylate NF-kappaB/p65. PKC delta delays the translocation of active NF-kappaB/p65 into the nucleus. PMA-induced cell death occurred if the phospho-NF-kappaB/p65 was prohibited from entering the nucleus in PKC delta positive cells. Translocation of phosphorylated form of NF-kappaB into the nucleus is critical in GBM cell proliferation.
Mut
Melike
M
Hacettepe University, Faculty of Medicine, Department of Neurosurgery, Ankara, Turkey. melikem@hacettepe.edu.tr
Amos
Samson
S
Hussaini
Isa M
IM
D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005909:Glioblastoma / Q000378:metabolism*; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D008301:Maleimides / Q000494:pharmacology; D016328:NF-kappa B / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D051571:Protein Kinase C-alpha / Q000378:metabolism*; D051745:Protein Kinase C-delta / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014443:Tyrosine / Q000378:metabolism
D004791:Enzyme Inhibitors; D007211:Indoles; D008301:Maleimides; D016328:NF-kappa B; D014443:Tyrosine; D012694:Serine; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D051745:Protein Kinase C-delta; C088060:bisindolylmaleimide; D013755:Tetradecanoylphorbol Acetate