Tumor stem cells (CD271, c-kit, SOX10) in Melanomas: prognostic and outcome implications

Melanoma cells that express stem cell marker CD271 are shown to form tumors when transplanted into nude or immunodeficient mice. These tumors have a higher metastatic potential and worse prognosis than melanomas resulting from transplantation of CD271-negative cells. We studied stem cell markers (CD271, c-kit, SOX1O) in melanomas, correlating their presence with prognostic factors and outcome. A total of 82 melanomas in tissue microarrays were immunostained for CD271, c-kit, and SOX10. Results were correlated with clinicopathologic prognostic parameters (Breslow depth of invasion, Clark level, sentinel lymph node status, and pathologic stage) and outcome (recurrence, metastases, and death). Of the 82 melanomas, CD271 was expressed in 18 (21%), c-kit in 47 (57%), and SOX10 in all (100%). CD271 does show correlation with metastases (P=0.05). c-kit is associated with favorable prognostic parameters [Breslow depth (P<0.001) and pathologic stage (P=0.02)] and with improved outcome [recurrence (P=0.03) and metastases (P=0.004)]. Although SOX10 is a good diagnostic marker, it cannot be used for prognosis because it is expressed in all the melanomas studied. In conclusion, CD271 expression in melanomas is associated with increased frequency of metastases, and c-kit immunoreactivity is associated with favorable prognostic parameters and improved outcome.