The γ-secretase inhibitor GSI-I interacts synergistically with the proteasome inhibitor bortezomib to induce ALK+ anaplastic large cell lymphoma cell apoptosis

Abstract

Single agent treatment of the γ-secretase inhibitor (GSI-I) or proteasome inhibitor in anaplastic lymphoma kinase positive anaplastic large cell lymphoma (ALK+ ALCL) shows limited response and considerable toxicity. Here, we examined the effects of the combination of low dose GSI-I and the proteasome inhibitor bortezomib (BTZ) in ALK+ ALCL cells in vivo and in vitro. We found that ALK+ ALCL cells treated with the BTZ and GSI-I combination treatment showed elevated apoptosis, consistent with increased caspase activation, compared with BTZ or GSI-I alone. The combination treatment also inhibited AKT and extracellular signal-related kinase pathways, as well as stress-related cascades, including the c-jun N-terminal kinase and stress-activated kinases. Moreover, combined treatment in a murine xenograft model resulted in increased apoptosis in tumor tissues and reduced tumor growth. Our results reveal the synergistic anti-tumor effects of low dose inhibitors against γ-secretase and the proteasome and suggest the potential application of the tolerable BTZ/GSI-I combined agents in treating ALK+ ALCL in future clinical treatment.