Background Bortezomib is an FDA-approved proteasome inhibitor, and oncolytic HSV-1 (oHSV) is a promising therapeutic approach for cancer. We tested the impact of combining bortezomib with oHSV for anti-tumor efficacy. Methods The synergistic interaction between oHSV and bortezomib was calculated using Chou-Talalay analysis. Viral replication was evaluated using plaque assay and immune fluorescence. Western-blot assays were used to evaluate induction of ER stress and unfolded protein response (UPR). Inhibitors targeting Hsp90 were utilized to investigate the mechanism of cell killing. Anti-tumor efficacy in vivo was evaluated using subcutaneous and intracranial tumor xenografts of glioma and head and neck cancer. Survival was analyzed by Kaplan-Meier curves and two-sided log rank test. Results Combination treatment with bortezomib and oHSV, 34.5ENVE, displayed strong synergistic interaction in ovarian cancer, head & neck cancer, glioma, and malignant peripheral nerve sheath tumor (MPNST) cells. Bortezomib treatment induced ER stress, evident by strong induction of Grp78, CHOP, PERK and IRE1α (western blot analysis) and the UPR (induction of hsp40, 70 and 90). Bortezomib treatment of cells at both sublethal and lethal doses increased viral replication (p value <0.001), but inhibition of Hsp90 ablated this response, reducing viral replication and synergistic cell killing. The combination of bortezomib and 34.5ENVE significantly enhanced anti-tumor efficacy in multiple different tumor models in vivo. Conclusions The dramatic synergy of bortezomib and 34.5ENVE is mediated by bortezomib- induced UPR and warrants future clinical testing in patients.
Bortezomib-induced unfolded protein response increases oncolytic HSV-1 replication resulting in synergistic, anti-tumor effects
[Category] 대상포진,
[Article Type] Article
[Source] PMC
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