Precisely engineering a dual-drug cooperative nanoassembly for proteasome inhibition-potentiated photodynamic therapy

Photodynamic therapy (PDT) has been widely investigated for cancer therapy. The intracellular accumulation of reactive oxygen species (ROS)-damaged protein facilitates tumor cell apoptosis. However, there is growing evidence that the ubiquitin-proteasome pathway (UPP) significantly impedes PDT by preventing the enrichment of ROS-damaged proteins in tumor cells. To tackle this challenge, we report a facile dual-drug nanoassembly based on the discovery of an interesting co-assembly of bortezomib (BTZ, a proteasome inhibitor) and pyropheophorbide a (PPa) for proteasome inhibition-mediated PDT sensitization. The precisely engineered nanoassembly with the optimal dose ratio of BTZ and PPa demonstrates multiple advantages, including simple fabrication, high drug co-loading efficiency, flexible dose adjustment, good colloidal stability, long systemic circulation, favorable tumor-specific accumulation, as well as significant enrichment of ROS-damaged proteins in tumor cells. As a result, the cooperative nanoassembly exhibits potent synergistic antitumor activity in vivo. This study provides a novel dual-drug engineering modality for multimodal cancer treatment.