Expression of the stem cell marker nestin in peripheral blood of patients with melanoma

Background There is continued interest in markers indicative of circulating melanoma cells. Nestin is a neuroepithelial intermediate filament protein that was found to be expressed in melanoma and in various cancer stem cells.

Objectives We investigated expression of nestin in peripheral blood of patients with melanoma.

Methods We analysed nestin expression by flow cytometry and by quantitative reverse transcription–polymerase chain reaction both in tissues (n = 23) and in blood samples (n = 102) from patients with American Joint Committee on Cancer stage III–IV melanoma. Forty-six negative controls were also added.

Results Flow cytometry did not reveal nestin-expressing cells in peripheral blood of healthy volunteers. In patients with melanoma, however, nestin protein was expressed in a proportion of melanoma cells enriched from peripheral blood by immunomagnetic sorting. In melanoma tissue samples a significant correlation was found between mRNAs coding for nestin and tyrosinase (P = 0·001) and melan-A (P = 0·002), whereas in blood a significant correlation was observed only for tyrosinase (P = 0·015), but not for melan-A (P = 0·53). Nestin expression was higher in stage IV patients compared with stage III/IV with no evidence of disease, in patients with high tumour burden, and was positively correlated to expression of tyrosinase and melan-A.

Conclusions Nestin was found to be an additional marker of interest for circulating melanoma cells. Prospective studies should investigate its potential added informative value in comparison with markers already in use for melanoma cell detection.