Multidrug resistance (MDR) and adverse effects of chemotherapeutic agents are severe issues in clinical cancer treatment. Due to the dysregulation of enzymes in the cancer cells, enzyme-responsive drug delivery systems (DDSs) have been considered as a viable technology for cancer chemotherapy. In the present work, doxorubicin (DOX) is visible after leaving from AuNR-LAX. After treatment with AuNR-LAX, the drug resistance index of DOX-resistant MCF-7/ADR cells was reduced from extremely high 955.0 to 1.7, implying high potential of AuNR-LAX in the MDR phenotype cancer treatment. In addition, the cellular viability of both MCF-7 and MCF-7/ADR cells decreased from 50% to 80% after treatment with AuNR-LAX along (equivalent DOX concentration = 2.3 μg/mL, Au concentration = 30 μg/mL) to below 10% after AuNR-LAX treatment plus radiation of 808 nm, due to the NIR photothermal effect of AuNRs. Human bronchial epithelial cell line 16HBE was chosen to evaluate the adverse effect of AuNR-LAX on the normal cells. At the low concentration, the cytotoxicity of LAX and AuNR-LAX is comparable for breast cancer cell MCF-7 and normal cell 16HBE. It is noted that, at high concentration (with equivalent DOX concentration = 13.1 μg/mL, Au concentration = 167.7 μg/mL), the cellular viability of 16HBE cells is over 50%, whereas that of MCF-7 cancer cells is close to 0, implying the potential of AuNR-LAX in reducing the adverse effects of DOX against normal cells/tissues. Overall, AuNR-LAX showed high potential in overcoming MDR and alleviating adverse effect on normal cells.
Keywords: adverse effect; cathepsin B; enzyme-responsive release; gold nanorod; multidrug resistance.