micro RNA ‐21 is upregulated in malignant melanoma and influences apoptosis of melanocytic cells

Overexpression of micro RNA ‐21 (mi R ‐21) has been observed in various cancer types, but little is known about the role of mi R ‐21 in melanoma. In this study, we demonstrate that levels of mi R ‐21 are significantly increased in primary melanoma tissues as compared to benign nevi and in human melanoma cell lines as compared to melanocytic cell preparations. We show that downregulation of mi R ‐21 in melanoma cell lines with high endogenous mi R ‐21 expression induced apoptosis, whereas proliferation was not significantly altered. Upregulation of mi R ‐21 in melanocytes resulted in increased proliferation and decreased apoptosis. However, in the MEWO melanoma cells with low endogenous mi R ‐21 expression, upregulation of mi R ‐21 had no functional effects. These findings indicate a potential pathogenetic role of mi R ‐21 upregulation in a subgroup of melanomas.