HMGB1 enhances chemotherapy resistance in multiple myeloma cells by activating the nuclear factor-κB pathway

Chemotherapy resistance is a main obstacle in the clinical chemotherapeutic treatment of multiple myeloma (MM). High-mobility group box 1 (HMGB1) has been revealed to be associated with the sensitivity of MM cells to chemotherapy, but how HMGB1 regulates chemotherapy resistance in MM has yet to be fully elucidated. In the present study, the exact molecular mechanism underlying HMGB1-mediated drug resistance in MM was explored using three chemotherapy-resistant MM cells (RPMI8226/ADR, RPMI8226/BOR and RPMI8226/DEX) that were successfully established. Reverse transcription-quantitative polymerase chain reaction revealed that the three chemotherapy-resistant MM cells exhibited a higher release of HMGB1 compared with the parental RPMI8226 cells. Interference with endogenous HMGB1 increased the sensitivity of drug-resistant MM cells to chemotherapy, which was supported by the low IC(50) value and the enlargement of cell apoptosis. Furthermore, short hairpin (sh)RNA-transfected MM cells showed an obvious elevation in phosphorylated (p)-IKKα/β, p-IκBα and p-p65 in whole cell lysate and/or nucleus, and treatment of nuclear factor (NF)-κB activator reversed the effect of shHMGB1-mediated cell viability and apoptosis in MM cells. In conclusion, HMGB1 regulates drug resistance in MM cells by regulating NF-κB signaling pathway, suggesting that HMGB1 has the potential to serve as a target for MM treatment.