Hair shaft miRNA-221 levels as a new tumor marker of malignant melanoma.

miRNA-221 (miR-221) is known to be abnormally expressed in many human cancers. The serum levels of miR-221 have been reported as a tumor marker for malignant melanoma (MM). We hypothesized that the hair shaft miR-221 levels may be increased in patients with MM. We therefore assessed the possibility that hair shaft miR-221 levels could be a marker for MM. The hair shaft miR-221 levels were significantly higher in patients with MM than controls. The rates of increased hair shaft miR-221 levels above the cut-off value were comparable to those of serum 5-S-CD, which is a tumor marker commonly used for MM. Measurements of the hair shaft miR-221 levels could have potential clinical value in the detection of MM. This is the first report investigating the hair shaft levels of an miRNA in patients with MM. Our investigations offer new insight into the relationship between miR-221 and MM, and may provide a new, non-invasive way to screen for melanoma.