microRNA and cancer progression in breast tumors

miRNAs are small non-coding RNAs frequently altered in human malignancies. They regulate protein-coding gene expression by mediating mRNA degradation and/or repressing translation via the association with the 3’ untranslated region (3’ UTR) of the mRNAs. Aberrant miRNA expression can influence several gene networks and pathways implicated in tumorigenesis and metastasis formation. To reveal miRNAs involved in breast cancer progression we investigated miRNA expression in 77 ductal breast carcinoma biopsies and 17 mammoplasties by microarray analysis. 16 differentially expressed miRNAs were identified comparing patients with or without disease relapse within 72 months from surgery. We have performed a microarray miRNA expression analysis on 77 ductal breast carcinoma biopsies and 17 normal tissues from mammoplastic reductions using the Human Agilent platform (V2). 77 frozen tumor specimens were selected from the Tumor Bank of the Department of Obstetrics and Gynecology, University of Turin. They were obtained from patients who underwent primary surgical treatment between 1988 and 2001 at a median age of 54 years (25-82). Eligibility criteria were the following: diagnosis of invasive breast cancer, all T and N stages, no distant metastasis at diagnosis (M0), complete clinical-pathological data and updated follow up. All patients were treated with radical modified mastectomy or quadrantectomy and axillary dissection plus breast irradiation. As normal breast controls 17 frozen mammoplastic reductions (EPFL, Lausanne) were included in the screening. Appropriate ethical approval was obtained for this study.