Mitochondria-Mediated HSP Inhibition Strategy for Enhanced Low-Temperature Photothermal Therapy.

Low-temperature photothermal therapy (PTT) has the advantage of causing less damage to normal tissues and has attracted great attention in recent years. However, the efficacy of low-temperature PTT is restricted by the overexpression of heat shock proteins (HSPs), specifically HSP70 and HSP90. Inhibiting the function of these HSPs is a major strategy used in the development of new cancer therapies. Herein, we designed four T780T-containing thermosensitive nanoparticles to interrupt the energy supply for HSP expression using their TPP-based mitochondrial targeting action. The reversal behavior of the nanoparticles on the gambogic acid (GA)-induced compensatory increase of HSP70 was investigated by Western blot and by immunohistochemistry. The anticancer efficacy of the low-temperature PTT based on these thermosensitive nanoparticles was also systematically examined. The design proposes for the first time to utilize and elucidate the mechanism of the mitochondrial targeting of T780T-containing NPs in synergy with the HSP90 inhibition of GA to achieve an effective low-temperature PTT. This work not only provides a novel pathway for the dual inhibition of HSP70 and HSP90 but also opens up a new approach for low-temperature PTT of tumors.