Chemotherapeutic drugs frequently encounter multidrug resistance. ATP from mitochondria helps overexpression of drug efflux pumps to induce multidrug resistance, so mitochondrial delivery as a means of "repurposing'' chemotherapeutic drugs currently used in the clinic appears to be a worthwhile strategy to pursue for the development of new anti-drug-resistant cancer agents. TPP-Pluronic F127-hyaluronic acid (HA) (TPH), with a mitochondria-targeting triphenylphosphine (TPP) head group, was first synthesized through ester bond formation. Paclitaxel (PTX)-loaded TPH (TPH/PTX) nanomicelles exhibited excellent physical properties and significantly inhibited A549/ADR cells. After TPH/PTX nanomicelles entered acidic lysosomes through macropinocytosis, the positively charged TP/PTX nanomicelles that resulted from degradation of HA by hyaluronidase (HAase) in acidic lysosomes were exposed and completed lysosomal escape at 12 h, finally localizing to mitochondria over a period of 24 h in A549/ADR cells. Subsequently, TPH/PTX caused mitochondrial outer membrane permeabilization (MOMP) by inhibiting antiapoptotic Bcl-2, leading to cytochrome C release and activation of caspase-3 and caspase-9. In an A549/ADR xenograft tumor model and a drug-resistant breast cancer-bearing mouse model with lung metastasis, TPH/PTX nanomicelles exhibited obvious tumor targeting and significant antitumor efficacy. This work presents the potential of a single, nontoxic nanoparticle (NP) platform for mitochondria-targeted delivery of therapeutics for diverse drug-resistant cancers.
Keywords: Cancer therapy; Mitochondrial targeting; Multidrug resistance; Nanomicelles; Paclitaxel.