The circulating microRNA-221 level in patients with malignant melanoma as a new tumor marker

Abstract Background MicroRNA-221 (miR-221) is known to be abnormally expressed in malignant melanoma (MM) cells, and it favors the induction of the malignant phenotype through down-modulation of p27Kip1/CDKN1B and the c-KIT receptor. This suggests that the serum level of miR-221 might increase in patients with MM and thus could be used as a new tumor marker. Objective To evaluate the possibility that the serum miR-221 level can be a marker of MM. Methods Serum samples were obtained from 94 MM patients and 20 healthy controls. MicroRNAs were purified from serum, and miR-221 levels were measured by quantitative real-time polymerase chain reaction. Results Circulating miR-221 was detectable and could be quantified in serum samples. MM patients had significantly higher miR-221 levels than healthy controls. Among the MM patients, the miR-221 levels were significantly increased in patients with stage I–IV MM compared to those with MM in situ , and the levels were correlated with tumor thickness. Moreover, a longitudinal study revealed a tendency for the miR-221 levels to decrease after surgical removal of the primary tumor, and to increase again at recurrence. Conclusions Serum levels of miR-221 were significantly increased in MM patients and may be useful not only for the diagnosis of MM, but also for the differentiating MM in situ from stage I–IV MM, and for evaluating tumor progression and monitoring patients during the follow-up period. In addition, considering that the serum levels of miR-221 were correlated with tumor thickness, miR-221 might also be useful as a prognostic marker for patients with MM.