Advertisement

The proteasome inhibitor PS-341 potentiates sensitivity of multiple myeloma cells to conventional chemotherapeutic agents: therapeutic applications

Nicholas Mitsiades, Constantine S. Mitsiades, Paul G. Richardson, Vassiliki Poulaki, Yu-Tzu Tai, Dharminder Chauhan, Galinos Fanourakis, Xuesong Gu, Charles Bailey, Marie Joseph, Towia A. Libermann, Robert Schlossman, Nikhil C. Munshi, Teru Hideshima and Kenneth C. Anderson

Abstract

The proteasome inhibitor PS-341 inhibits nuclear factor-κB (NF-κB) activation, induces apoptosis in cancer cells, including multiple myeloma (MM) cells, and has marked clinical activity as a monotherapy for MM. In this study, we found that subtoxic concentrations of PS-341 potently sensitized MM cell lines and patient cells to DNA-damaging chemotherapeutic agents such as doxorubicin and melphalan, including cells resistant to these drugs and those isolated from a patient who had relapsed after PS-341 monotherapy. Moreover, PS-341 abolished cell adhesion–mediated drug resistance. Using gene expression profiling and proteomic analysis, we demonstrate that PS-341, among its other proapoptotic effects, down-regulates the expression of several effectors involved in the cellular response to genotoxic stress. These data suggest that, in addition to down-regulating the expression of apoptosis inhibitors, PS-341 inhibits genotoxic stress response pathways and thereby restores sensitivity to DNA-damaging chemotherapeutic agents. These studies, therefore, provide the framework for clinical use of this agent in combination with conventional chemotherapy.

  • Submitted June 14, 2002.
  • Accepted October 17, 2002.
View Full Text