Hypocrellin B triggered sonodynamic therapy reverses multidrug resistance of doxorubicin-resistant SGC7901/ADR cells via down-regulation of P-gp expression.

The combating of multidrug resistance (MDR) plays a crucial role in effective chemotherapy. However, current strategies for cancer of MDR remain unsatisfactory for their limited efficacy and severe side effects. In this study, we sought to determine the anti-MDR effects of a traditional chinese herb, Hypocrellin B (HB)-mediated sonodynamic therapy (HB-SDT) on human gastric multidrug resistance cancer SGC-7901cell/ADR cells and its underlying mechanisms. HB-SDT can synergistically increase the cytotoxicity of DOX on SGC-7901cell/ADR cells in which the mechanism is related to significant promotion of apoptosis, ROS level and drop of MMP in the resistant cells after combining treatment of DOX and HB-SDT. Meanwhile, western blotting assays display the expression of apoptosis related proteins Bax and Bcl-2 changed markedly after the combination treatment. In addition, the expression of P-gp was significantly down-regulated after treatment of HB-SDT and DOX. HB-SDT can increase DOX-induced mitochondrial-dependent apoptosis by inhibiting the expression of P-gp, thereby increasing the cytotoxic effect into SGC7901/ADR cells.