Parkin-induced Decrease of -catenin is Mediated by Protein Kinase C in TNF--treated HeLa Cells

Parkin is a protein known to have tumor suppressive functions. In a previous study, we determined that Parkin expression restores susceptibility to TNF-${\alpha}$-induced death in HeLa cells. ${\beta}$-catenin is a key protein in the Wnt signaling pathway and excessive activation of the ${\beta}$-catenin pathway can promote cancer development. In this study, we found that ${\beta}$-catenin levels decreased dramatically in Parkin over-expressing HeLa cells treated with TNF-${\alpha}$. We used chemical inhibitors of cell signaling pathways to identify the signaling molecules involved in ${\beta}$-catenin down-regulation. Our results indicate that the PKC inhibitor (RO-31-7549) blocked parkin-induced down-regulation of ${\beta}$-catenin. We also show that Parkin-induced decrease in cell viability in TNF-${\alpha}$-treated HeLa cells is alleviated upon treatment with a PKC inhibitor. Taken together, these results suggest the possibility that ${\beta}$-catenin reduction may be associated with Parkin-induced decrease of cell viability in TNF-${\alpha}$ treated HeLa cells.