High expression of Dicer reveals a negative prognostic influence in certain subtypes of primary cutaneous T cell lymphomas

Background: Aberrant expression of microRNAs (miRNAs) has been implicated in oncogenesis of various tumors and primary cutaneous T cell lymphomas. Dicer, a ribonuclease III-like enzyme is essential for miRNA processing. Objective: We initiated a retrospective study to characterize the alterations in the expression profile of Dicer in patients with primary cutaneous T cell lymphomas (CTCL). Methods: A total of 50 consecutive patients with primary CTCL were studied, with the majority having mycosis fungoides (n = 34). Five patients had primary cutaneous CD 30+ anaplastic large cell lymphoma, four patients each had lymphomatoid papulosis and primary cutaneous CD4-positive small/medium T-cell lymphoma, one primary cutaneous gamma delta I cell lymphoma, one Sezary syndrome and another subcutaneous panniculitis-like T cell lymphoma of alpha beta-phenotype. Immunohistochemistry was performed on paraffin sections using a commercially available antibody against Dicer. Intensity of expression was correlated with clinical parameters including disease specific survival (DSS) and time to progression (TTP). Results: After a median follow-up of 74 months (range: 1-271), 12/50 patients (24%) have died. Univariate and multivariate analysis for disease-specific survival showed Dicer expression and stage as a negative predictive factor in the sole group of MF patients (n = 34) as well as in the heterogeneous group of patients (n = 50), but not gender, histological subtype, primary localization of disease, age and recurrence of lymphoma (p > 0.05). Conclusion: Our data suggest Dicer expression as a possible molecular marker in patients with MF and apparently indicate that miRNA(s) might be of clinical relevance in CTCL. (C) 2011 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.