MicroRNAs (miRNAs), which are small non-coding RNA molecules
that post-transcriptionally regulate the expression of target genes, control
the vast majority of cellular events, including proliferation, differentiation,
survival, senescence, autophagy, metabolism and genome stability.
Even slight alterations in miRNA expression levels may induce the development
of pathological states, including cancer. Several studies have already
demonstrated the importance of miRNAs in the regulation of melanocytes.
Upregulation of oncogenic miRNAs (oncomiRs), mainly by amplification
and translocation of miRNA genes, and downregulation of oncosuppressor
miRNAs (anti-oncomiRs) by deletion and other mutations, promoter methylation
and abnormal processing contributes to melanoma initiation and progression. At each
phase of melanoma progression, tumor cells exhibit distinct profiles of miRNA expression,
as compared with normal melanocytes. Moreover, as miRNAs are stable molecules that can
be identified in bodily fluids, such as blood and saliva, they can serve as potent non-invasive
prognostic markers of disease progression and response to therapy. This review summarizes
recent findings regarding miRNA-mediated control of melanocytes and melanoma development,
and presents miRNAs as prognostic markers for this disease.