Abstract
Increased nuclear factor κB (NF-κB) activity is associated with increased tumor cell survival in multiple myeloma. The function of NF-κB is inhibited through binding to its inhibitor, IκB. Release of activated NF-κB follows proteasome-mediated degradation of IκB resulting from phosphorylation of the inhibitor and, finally, conjugation with ubiquitin. We report that myeloma cells have enhanced IκBα phosphorylation and increased NF-κB activity compared with normal hematopoietic cells. The proteasome inhibitor PS-341 blocked nuclear translocation of NF-κB, blocked NF-κB DNA binding, and demonstrated consistent antitumor activity against chemoresistant and chemosensitive myeloma cells. The sensitivity of chemoresistant myeloma cells to chemotherapeutic agents was markedly increased (100,000-1,000,000-fold) when combined with a noncytotoxic dose of PS-341 without affecting normal hematopoietic cells. Similar effects were observed using a dominant negative super-repressor for IκBα. Thus, these results suggest that inhibition of NF-κB with PS-341 may overcome chemoresistance and allow doses of chemotherapeutic agents to be markedly reduced with antitumor effects without significant toxicity.
Original language | English (US) |
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Pages (from-to) | 1136-1144 |
Number of pages | 9 |
Journal | Clinical Cancer Research |
Volume | 9 |
Issue number | 3 |
State | Published - Mar 1 2003 |
ASJC Scopus subject areas
- Oncology
- Cancer Research