Turkish Neurosurgery 2010 , Vol 20 , Num 3
PKC Alpha Phosphorylates Cytosolic NF-kappaB/p65 and PKC Delta Delays Nuclear Translocation of NF-kappaB/p65 in U1242 Glioblastoma Cells
Melike MUT1,2, Samson AMOS3, Isa M HUSSAINI4
1Hacettepe University, Faculty of Medicine, Department of Neurosurgery, Ankara, Turkey
2Hacettepe University, Institute of Neurological Sciences and Psychiatry, Ankara, Turkey
3,4University of Virginia, Department of Pathology, Charlottesville VA, USA
DOI : 10.5137/1019-5149.JTN.3008-10.1 AIM: 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.

MATERIAL and METHODS: The activation of NF-kappaB by PKC α and PKC δ was assessed by Western blotting after the stimulation with Phorbol 12- Myristate 13-Acetate (PMA). Gene silencing of PKC α , PKC δ 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 α. Gene silencing with siRNA against NF-kappaB/p65 inhibited [3H]-thymidine incorporation in U1242 GBM cells. PKC δ decelerated the nuclear translocation of activated NF-kappaB/p65 up to 4 hours after the stimulation. PMA induced death was not observed in PKC δ silenced cells where activated NF-kappaB/p65 was located immediately in the nucleus.

CONCLUSION: NF-kappaB/p65 is pro-survival and proliferative factor in U1242 GBM cells. PKC α is needed to phosphorylate NF-kappaB/p65. PKC δ delays the translocation of active NF-kappaB/p65 into the nucleus. PMAinduced cell death occurred if the phospho-NF-kappaB/p65 was prohibited from entering the nucleus in PKC δ positive cells. Translocation of phosphorylated form of NF-kappaB into the nucleus is critical in GBM cell proliferation. Keywords : Glioblastoma, NF-kappaB, PKC, Proliferation, Survival

Corresponding author : Melike Mut, melikem@hacettepe.edu.tr