TAT-modified nanosilver for combating multidrug-resistant cancer.

A nanopharmaceutical system using TAT-enhanced cell/tissue penetration strategy was developed for multidrug-resistant (MDR) cancer treatment, in which nanocrystalline silver with mean size of 8 nm modified with TAT cell-penetrating peptide (termed AgNP-TAT) displayed extraordinary antitumor activity in both MDR cells and non-resistant cells at an indiscriminating manner. Such anti-MDR effect is presumably due to the size-exclusion effect, by which the nanoparticles are too large to be pumped out. Of note, AgNP-TAT showed significant enhancement in killing tumor cells, e.g. up to 24 fold higher compared to its counterpart without TAT-modification. The animal studies further confirmed the success of our strategy that AgNP-TAT was able to effectively inhibit the tumor growth in the mice bearing malignant melanoma at a dose of 1 nmol/kg, compared with the effective dose (4.3 μmol/kg) of doxorubicin. AgNP-TAT also showed significantly reduced adverse toxicity in vivo. It indicates AgNP-TAT could be a class of nano drug for MDR cancer treatment.