PKC Alpha Phosphorylates Cytosolic NF-kappaB/p65 and PKC Delta Delays Nuclear Translocation of NF-kappaB/p65 in U1242 Glioblastoma Cells
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.
Glioblastoma, NF-kappaB, PKC, proliferation, survival
Mut, Melike; Amos, Samson; and Hussaini, Isa M., "PKC Alpha Phosphorylates Cytosolic NF-kappaB/p65 and PKC Delta Delays Nuclear Translocation of NF-kappaB/p65 in U1242 Glioblastoma Cells" (2010). Pharmaceutical Sciences Faculty Publications. 90.