Single-marker identification of head and neck squamous cell carcinoma cancer stem cells with aldehyde dehydrogenase

Background. In accord with the cancer stem cell (CSC) theory, only a small subset of cancer cells are capable of forming tumors. We previously reported that CD44 isolates tumorigenic cells from head and neck squamous cell cancer (HNSCC). Recent studies indicate that aldehyde dehydrogen- ase (ALDH) activity may represent a more specific marker of CSCs. Methods. Six primary HNSCCs were collected. Cells with high and low ALDH activity (ALDH high /ALDH low ) were isolated. ALDH high and ALDH low populations were implanted into NOD/