Proteomic identification of 14-3-3ε as a linker protein between pERK1/2 inhibition and BIM upregulation in human osteosarcoma cells

Abstract

Despite advancements in multimodality chemotherapy, conventional cytotoxic treatments still remain ineffective for a subset of patients with aggressive metastatic or multifocal osteosarcoma. It has been shown that pERK1/2 inhibition enhances chemosensitivity to doxorubicin and promotes osteosarcoma cell death in vivo and in vitro. One of the pro-apoptotic mechanisms is upregulation of Bim by pERK1/2 inhibitors. To this end, we examined proteomic changes of 143B human osteosarcoma cells with and without treatment of PD98059, pERK1/2 inhibitor. Specifically, we identified 14-3-3ε protein as a potential mediator of Bim expression in response to inhibition of pERK1/2. We hypothesized that 14-3-3ε mediates upregulation of Bim expression after pERK1/2 inhibition. We examined the expression of Bim after silencing 14-3-3ε using siRNA. The 14-3-3ε gene silencing resulted in downregulation of Bim expression after PD98059 treatment. These data indicate that 14-3-3ε is required for Bim expression and that it has an anti-cancer effect under pERK1/2 inhibition in 143B cells. By playing an essential role upstream of Bim, 14-3-3ε may potentially be a coadjuvant factor synergizing the effect of pERK1/2 inhibitors in addition to conventional cytotoxic agents for more effective osteosarcoma treatments. © 2014 Orthopaedic Research Society.