Activation of β-catenin by inhibitors of glycogen synthase kinase-3 ameliorates cisplatin-induced cytotoxicity and pro-inflammatory cytokine expression in HEI-OC1 cells

Cisplatin is used in the treatment of a wide variety of solid tumors, but its use is limited by its serious adverse effects, including ototoxicity. Glycogen synthase kinase-3 (GSK-3) is a ubiquitously expressed serine/threonine kinase that regulates a variety of cellular functions by phosphorylating its substrates. However, the otoprotective effect of GSK-3 inhibitors is poorly understood. Here, we investigated whether GSK-3 is involved in cisplatin-induced ototoxicity in HEI-OC1 cells and organs of Corti (OCs). GSK-3 inhibitors suppressed cisplatin-induced apoptosis determined by decreased p53 activity, and also decreased expression of PARP and p53 target genes such as p21 and PUMA. The effect of GSK-3 inhibitors was mediated by markedly increased nuclear β-catenin that in turn blocked nuclear translocation of NF-κB. siRNA-mediated β-catenin knockdown markedly increased the expression of NF-κB target genes, such as TNF-α and IL-6. Our data suggest that the GSK-3/β-catenin pathway may play a central role in cisplatin-mediated cytotoxicity in HEI-OC1 cells and hair cells of OCs in vitro.