Protein kinase C-ζ regulates transcription of the matrix metalloproteinase-9 gene induced by IL-1 and TNF-α in glioma cells via NF-κB

Abstract

The regulation of matrix metalloproteinase-9 (MMP-9) expression in glioma cells is one of the key processes in tumor invasion through the brain extracellular matrix. Although some studies have demonstrated the implication of classic protein kinase C (PKC) isoforms in the regulation of MMP-9 production by phorbol esters or lipopolysaccharide, the involvement of specific PKC isoforms in the signaling pathways leading to MMP-9 expression by inflammatory cytokines remains unclear. Here we report that the atypical PKC-ζ isoform participates in the induction of MMP-9 expression by interleu. kin-1 (IL-1) and tumor necrosis factor-α (TNF-α) in rat C6 glioma cells. Indeed, zymography and semi-quantitative reverse transcriptase-PCR analysis showed that pretreatment of C6 cells with PKC-ζ pseudosubstrate abolished MMP-9 activity and gene expression induced by IL-1 or TNF-α. Accordingly, IL-1 and TNF-α were able to induce PKC-ζ activity, as demonstrated by in vitro kinase assay using immunoprecipitated PKC-ζ. Furthermore, stable C6 clones overexpressing PKC-ζ, but not PKC-ε, displayed an up-regulation of MMP-9 constitutive expression as well as an increase of mmp-9 promoter activity. These processes were inhibited by an NF-κB-blocking peptide and completely prevented by NF-κB-binding site mutation in the mmp-9 promoter. Taken together, these results indicate that PKC-ζ plays a key role in the regulation of MMP-9 expression in C6 glioma cells through NF-κB.