1. ¹Department of Plastic Surgery and Burn Unit, Faculty of Health Sciences, University of Copenhagen, Rigshospitalet, Denmark
2. ²Department of Clinical Biochemistry, Faculty of Health Sciences, University of Copenhagen, Rigshospitalet, Denmark
3. ³Department of Dermatology, Faculty of Health Sciences, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark
4. ⁴Department of Pathology, Faculty of Health Sciences, University of Copenhagen, Rigshospitalet, Denmark

Correspondence: Dr Martin Glud, Department of Plastic Surgery and Burn Unit, Faculty of Health Sciences, University of Copenhagen, Rigshospitalet, Blegdamsvej 9, Copenhagen 2100, Denmark. E-mail: martin.glud@dadlnet.dk

Received 25 July 2008; Accepted 2 September 2008; Published online 13 November 2008.

Abstract

MicroRNAs (miRNAs) are small, noncoding RNA molecules that regulate cellular differentiation, proliferation, and apoptosis. MiRNAs are expressed in a developmentally regulated and tissue-specific manner. Aberrant expression may contribute to pathological processes such as cancer, and miRNA may therefore serve as biomarkers that may be useful in a clinical environment for diagnosis of various diseases. Most miRNA profiling studies have used fresh tissue samples. However, in some types of cancer, including malignant melanoma, fresh material is difficult to obtain from primary tumors, and most surgical specimens are formalin fixed and paraffin embedded (FFPE). To explore whether FFPE material would be suitable for miRNA profiling in melanocytic lesions, we compared miRNA expression patterns in FFPE versus fresh frozen samples, obtained from 15 human melanocytic nevi. Out of microarray data, we identified 84 miRNAs that were expressed in both types of samples and represented an miRNA profile of melanocytic nevi. Our results showed a high correlation in miRNA expression (Spearman r-value of 0.80) between paired FFPE and fresh frozen material. The data were further validated by quantitative RT-PCR. In conclusion, FFPE specimens of melanocytic lesions are suitable as a source for miRNA microarray profiling.