Anthracyclines attenuate Nrf1-dependent proteolytic pathways and potentiate proteasome inhibitor cytotoxicity. (PubMed, Mol Biol Cell)
Proteasome inhibitors such as bortezomib, carfilzomib, and ixazomib are FDA-approved treatments for multiple myeloma, but resistance frequently limits their effectiveness...Importantly, aclarubicin, a non-DNA-damaging anthracycline, also attenuated Nrf1 transcriptional activity, indicating that DNA damage is not required for this inhibition. Doxorubicin co-treatment delayed proteasome recovery after pulse inhibition and partially restored sensitivity to carfilzomib in bortezomib-resistant U266 myeloma cells, consistent with genetic knockout of Nrf1. These findings identify a DNA-damage-independent mechanism by which anthracyclines directly obstruct Nrf1-mediated transcriptional induction. Thus, anthracyclines serve as chemical tools to probe the molecular control of proteostasis and suggest a strategy to mitigate Nrf1-driven adaptive response to proteasome inhibition.