Exocytosis of polyubiquitinated proteins in bortezomib-resistant leukemia cells: a role for MARCKS in acquired resistance to proteasome inhibitors
Proteasome inhibition has been recognized as a novel treatment modality in hematologic malignancies. Initially, the reversible proteasome inhibitor bortezomib demonstrated efficacy in multiple myeloma (MM), which supported its approval for relapsed and refractory MM in 2003. Later on, carfilzomib, a next-generation irreversible proteasome inhibitor was approved by the US FDA in July 2012 for relapsed/refractory MM. Currently, several other proteasome inhibitors are undergoing preclinical and clinical evaluation. The successes of proteasome inhibitors in MM are now being translated to other hematologic malignancies, including acute leukemia. The first clinical studies with bortezomib in leukemia revealed promising clinical activity, particularly when combined with conventional chemotherapeutics. In this review the position of proteasome inhibitors in acute leukemia treatment is summarized and discussed. Special focus is also attributed to immunoproteasome inhibitors. As a future perspective, it is anticipated that proteasome inhibitors may prove to be of added value in therapeutic interventions for acute leukemia.