Nigericin selectively targets cancer stem cells in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is prevalent in southern China, northern Africa, and Alaska. The prognosis for NPC patients at early stage is good, while it is poor for patients at late stages. Cancer stem cells (CSCs) have been proposed to be associated with tumor initiation, relapse and metastasis, and the poor prognosis of NPC likely results from residual CSCs after therapy. Study on the therapy targeting CSCs in NPC remains poor, though it received intensive attentions in other cancers. Here, we used NPC cell lines with high and low proportion of CSCs as models to explore the effect of nigericin, an antibiotic, on CSCs. We found that nigericin could selectively target CSCs and sensitize CSCs in NPC to the widely used clinical drug cisplatin both in vitro and in vivo. Moreover, downregulation of the polycomb group protein Bmi-1 may contribute to the inhibitory effect of nigericin on CSCs. Furthermore, by using the in vitro NPC cell models, we found that nigericin could significantly decrease the migration and invasion abilities, which are known to be associated with CSCs. Taken together, our results suggest that nigericin can selectively target CSCs in NPC, which could be a candidate CSCs targeting drug for clinical evaluation.