Identification of a subpopulation of nasopharyngeal carcinoma cells with cancer stem-like cell properties by high aldehyde dehydrogenase activity

Objectives/Hypothesis Cancer stem cells have been reported as a new therapeutic target in many cancers, but their existence in nasopharyngeal carcinoma (NPC) is largely unknown. This study was conducted to determine cancer stem-like cells in NPC cell line. Study Design Basic science experimental study. Methods Aldehyde dehydrogenase (ALDH) activity, a putative functional marker for cancer stem cells, was assessed in Epstein-Barr virus-associated NPC cell line C666-1 cells. The ability of cells with high and low ALDH activity to proliferate, resist therapy, and initiate tumor formation was compared. Results Enrichment of cancer stem-like cells (with high ALDH activity) in C666-1 was associated with a significantly greater ability to proliferate, be clonogenic, resist chemotherapy drugs and radiation, reconstitute a heterogeneous population, and express pluripotent markers. Furthermore, subcutaneous injection of these cells into immunodeficient nude mice resulted in a tendency of tumor formation at a higher rate as compared to cells with low ALDH activity. Conclusions These results provide evidence for the existence of cancer stem-like cells in the NPC cell line C666-1 cells.