A Strategy to Fight against Triple-Negative Breast Cancer: pH-Responsive Hexahistidine-Metal Assemblies with High-Payload Drugs.

Triple-negative breast cancer (TNBC), an aggressive subtype of breast cancer, is difficult to be targeted therapeutically due to negative expression of the bioreceptor, which leads to the poorest overall four-year survival rate among all cancer subtypes. We proposed that the nanomedicine featuring high payload and pH-responsive release of the loaded drugs could assist the TNBC treatment. In the present study, the His 6 -metal assemblies (HmA) were employed to encapsulate the doxorubicin (Dox), and the effect of HmA loaded with Dox (HmA@Dox) on treating TNBC was evaluated in vitro and in vivo. We found that the participation of Dox in the formation of HmA leads to high loading efficiency (99.4% for concentration ≤ 1 mg/mL) and the loading capacity (50.7% for concentration ≥ 10 mg/mL) of Dox encapsulated into HmA. HmA@Dox exhibited a narrow size distribution on the nanoscale, a pH-responsive release of loaded Dox, a quick endocytosis process, and fast lysosome escape. Most importantly, the HmA@Dox showed high efficacy in killing various breast cancer cells (MCF-7, MDA-MB-231, and MDA-MB-453) in vitro and depressing the development of TNBC in vivo. Our results demonstrated that such a strategy for designing a nanomedicine with high payload and responsive release of drugs to the environment around the tumor was of great importance to treat TNBC.