Dendritic cell (DCs) based immunotherapy is emerging as a useful tool to treat multiple myeloma (MM). Although several tumor target antigens have been used, the clinical effectiveness of the vaccination is still limited in the MM and the improvement o...
Dendritic cell (DCs) based immunotherapy is emerging as a useful tool to treat multiple myeloma (MM). Although several tumor target antigens have been used, the clinical effectiveness of the vaccination is still limited in the MM and the improvement of immunotherapeutic approach is clearly needed. Recently, bortezomib is known to increase the expression of heat shock protein (HSP) 90 on the surface of tumor cells for enhancing the antitumor immunity against cancer and the ability of bortezomib to kill tumor cells could be improved by inhibition of signal transducer and activator of transcription 3 (STAT3). In this study, I investigated whether bortezomib and JSI-124, an STAT3 inhibitor, could be synergistically used to generate potent cytotoxic T lymphocytes (CTLs) by inducing HSP expression in necrotic tumor cells to loading onto DCs. The combination of bortezomib and JSI-124 showed to induce necrotic cells mostly from tumor cells and led to increase the expression of HSP90 compared to bortezomib or JSI-124 alone. The ability to uptake tumor antigens that induced by bortezomib, JSI-124 or both was comparable in DCs and there was no significant difference in the phenotypic expression of DCs. DCs loaded with the combination of bortezomib and JSI-124 treated tumor cells showed the increased production of IL-12p70 during maturation as well as after CD40L stimulation compared to bortezomib or JSI-124 alone. Necrotic tumor cells treated by bortezomib, JSI-124 or both were not increased the production of IL-10 by DCs. CTLs stimulated by both bortezomib plus JSI-124 treated tumor cells-loaded DCs displayed a greater number of IFN-r-secreting cells against autologous tumor cells than did those stimulated by either bortezomib or JSI-124 treated tumor cells-loaded DCs. In conclusion, these results indicate that DCs loaded with necrotic tumor cells that induced by the treatment of bortezomib and JSI-124 could elicit potent antitumor activity of CTLs.