Selective inhibition of breast cancer stem cells by gold nanorods mediated plasmonic hyperthermia

Cancer stem cells (CSCs) have been identified in a variety of cancers and emerged as a new target for cancer therapy. CSCs are resistant to many current cancer treatments, including chemotherapy and radiation therapy. Therefore, eradication of this cell population is a primary objective in cancer therapy. Here, we report gold nanorods (AuNRs) mediated photothermal treatment can selectively eliminate CSCs in MCF-7 breast cancer cells. It significantly reduced the aldehyde dehydrogenase positive (ALDH+) cells subpopulation and the mammosphere formation ability of treated cells. Also, the gene expression of stem cell markers was decreased. Cellular uptake assay revealed that polyelectrolyte conjugated AuNRs could be internalized by CSCs much more and faster than non cancer stem cells (NCSCs), which might be the main reason for the selective elimination of CSCs. We further loaded salinomycin (SA), a CSCs inhibitor with polyelectrolyte conjugated AuNRs to get a synergistic CSCs inhibition. Enhanced inhibition of CSCs was obtained by NIR light triggered drug release and hyperthermia. This CSCs-targeted thermo-chemotherapy platform provides a new combinatorial strategy for efficient inhibition of CSCs, which is promising to improve cancer treatment and may overcome the chemoresistance and recurrence of cancer.