Altered microRNA expression in mycosis fungoides

Background MicroRNAs are small noncoding RNA molecules involved in the regulation of various physiological and pathological processes. Altered expression of different microRNAs has been observed in both solid tumours and haematological malignancies. Objectives To investigate expression of several microRNAs in early and advanced mycosis fungoides (MF). Methods Biopsies were obtained from 43 patients with MF (18 early MF and 25 advanced MF) and 23 healthy volunteers. After microRNA isolation, reverse transcriptase reactions were performed, followed by cDNA amplification. The following microRNAs were analysed: miR-15a, miR-16, miR-155, let-7a, let-7d and let-7f. The relative amount of each microRNA was normalized according to the reference RNU48 level. Results Among the microRNAs studied, only MiR-155 was found to be slightly overexpressed in MF compared with healthy controls. Early MF showed a higher level of all analysed microRNAs after normalization against RNU48 level. Furthermore, metastatic MF demonstrated lower concentrations of let-7a, let-7d and let-7f when compared with MF limited to the skin. The univariate survival analysis and multivariate Cox's regression model revealed that the level of let-7a expression was an independent prognostic indicator. Conclusions Altered expression of studied microRNAs and the differences between early and advanced MF may suggest that microRNAs play a significant role in MF pathogenesis. It seems that microRNAs could serve as potential therapeutic targets in the future.