Bortezomib and SAHA Synergistically Induce ROS-Driven Caspase-Dependent Apoptosis of Nasopharyngeal Carcinoma and Block Replication of Epstein–Barr Virus

Abstract

A novel drug combination of a proteasome inhibitor, bortezomib, and a histone deacetylase inhibitor, suberoylanilide hydroxamic acid (SAHA), was tested in nasopharyngeal carcinoma (NPC), both in vitro and in vivo. Dose-response of different concentrations of bortezomib and SAHA on inhibition of cell proliferation of NPC was determined. Mechanisms of apoptosis and effects on lytic cycle activation of Epstein-Barr virus (EBV) were investigated. Combination of bortezomib and SAHA (bortezomib/SAHA) synergistically induced killing of a panel of NPC cell lines. Pronounced increase in sub-G 1 , Annexin V-positive, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)-positive cell populations were detected after treatment with bortezomib/SAHA when compared with either drug alone. Concomitantly, markedly augmented proteolytic cleavage of PARP, caspase-3, -7, -8, and -9, reactive oxygen species (ROS) generation, and caspase-8-dependent histone acetylation were observed. ROS scavenger, N-acetyl cysteine, diminished the apoptotic effects of bortezomib/SAHA, whereas caspase inhibitor Z-VAD-FMK significantly suppressed the apoptosis without decreasing the generation of ROS. Bortezomib inhibited SAHA's induction of EBV replication and abrogated production of infectious viral particles in NPC cells. Furthermore, bortezomib/ SAHA potently induced apoptosis and suppressed the growth of NPC xenografts in nude mice. In conclusion, the novel drug combination of bortezomib and SAHA is highly synergistic in the killing of NPC cells in vitro and in vivo. The major mechanism of cell death is ROS-driven caspase-dependent apoptosis. Bortezomib antagonizes SAHA's activation of EBV lytic cycle in NPC cells. This study provides a strong basis for clinical testing of the combination drug regimen in patients with NPC. Mol Cancer Ther; 12(5); 747-58. Ó2013 AACR.

Monoclonal IgG in MGUS and multiple myeloma targets infectious pathogens

“…Existing drugs target the main signaling molecules or pathways altered by EBNA-1, notably p53/TP53, ubiquitin-and proteasome-dependent proteolysis, and the NF-κB pathway (40)(41)(42). Proteasome inhibitors that restore the presentation of EBNA-1-derived epitopes should be particularly useful in EBNA-1-associated MM, via the destruction of EBNA-1-expressing cells and subsequent reduction in EBNA-1 stimulation of clonal plasma cells (43)(44)(45). Proteasome inhibitors may also act directly on clonal plasma cells infected by EBV.…”

Proteasome inhibitor carfilzomib interacts synergistically with histone deacetylase inhibitor vorinostat in Jurkat T-leukemia cells

“…Previous studies have reported that proteasome inhibitor bortezomib and histone deacetylase inhibitors have synergistic interactions in a variety of malignancies [13,14]. Secondgeneration proteasome inhibitor CFZ has shown activity against bortezomib-resistant cells [7].…”

“…First-in-class proteasome inhibitor bortezomib and histone deacetylase inhibitors have been reported to have synergistic interactions in some solid tumors [13,14] and hematologic tumors [15,16]. CFZ is a second-generation irreversible proteasome inhibitor and has shown activity against bortezomibresistant cells, indicating that their mechanisms of action are not completely identical [7].…”

Role of ATM in the Formation of the Replication Compartment during Lytic Replication of Epstein-Barr Virus in Nasopharyngeal Epithelial Cells

“…HONE1-EBV cells and Daudi cells (a B lymphoblast cell line) were maintained in RPMI 1640 medium supplemented with 10% fetal bovine serum (FBS) and 1% penicillinstreptomycin (P/S). HONE1-EBV cells were established by infecting EBVnegative HONE1 cells with enhanced green fluorescent protein (EGFP)-tagged EBV (strain Akata) (33)(34)(35). The cells were grown at 37°C in a 5% CO 2 incubator.…”