The ubiquitin–proteasome system as a molecular target in solid tumors: an update on bortezomib

A Milano,¹ F Perri,² F Caponigro²

¹Sandro Pitigliani Medical Oncology Unit, Department of Oncology, Hospital of Prato, Istituto Toscano Tumori, Prato, Italy; ²Head and Neck Medical Oncology Unit, National Tumour institute of Naples, Naples, Italy

Abstract: The ubiquitin–proteasome system has become a promising molecular target in cancer therapy due to its critical role in cellular protein degradation, interaction with cell cycle and apoptosis regulation, and unique mechanism of action. Bortezomib (PS-341) is a potent and specific reversible proteasome inhibitor, which has shown strong in vitro antitumor activity as single agent and in combination with other cytotoxic drugs in a broad spectrum of hematological and solid malignancies. In preclinical studies, bortezomib induced apoptosis of malignant cells through the inhibition of NF-κB and stabilization of pro-apoptotic proteins. Bortezomib also promotes chemo- and radiosensitization of malignant cells in vitro and inhibits tumor growth in murine xenograft models. The proteasome has been established as a relevant target in hematologic malignancies and bortezomib has been approved for the treatment of multiple myeloma. This review summarizes recent data from clinical trials in solid tumors.

Keywords: proteasome, bortezomib, NF-κB, clinical studies, solid tumors