Bortezomib Amplifies Effect on Intracellular Proteasomes by Changing Proteasome Structure

Autor: David S. Pitcher, Kate de Mattos-Shipley, Konstantinos Tzortzis, Holger W. Auner, Anastasios Karadimitris, Maurits F. Kleijnen
Jazyk: angličtina
Rok vydání: 2015
Předmět:
Zdroj: EBioMedicine, Vol 2, Iss 7, Pp 642-648 (2015)
Druh dokumentu: article
ISSN: 2352-3964
DOI: 10.1016/j.ebiom.2015.05.016
Popis: The proteasome inhibitor Bortezomib is used to treat multiple myeloma (MM). Bortezomib inhibits protein degradation by inactivating proteasomes' active-sites. MM cells are exquisitely sensitive to Bortezomib – exhibiting a low-nanomolar IC50 – suggesting that minimal inhibition of degradation suffices to kill MM cells. Instead, we report, a low Bortezomib concentration, contrary to expectation, achieves severe inhibition of proteasome activity in MM cells: the degree of inhibition exceeds what one would expect from the small proportion of active-sites that Bortezomib inhibits. Our data indicate that Bortezomib achieves this severe inhibition by triggering secondary changes in proteasome structure that further inhibit proteasome activity. Comparing MM cells to other, Bortezomib-resistant, cancer cells shows that the degree of proteasome inhibition is the greatest in MM cells and only there leads to proteasome stress, providing an explanation for why Bortezomib is effective against MM but not other cancers.
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