The Unknown microRNA Expression of Male Breast Cancer. Similarities and Differences with Female Ductal Carcinoma. Their Role as Tumor Biomarker

Mature microRNAs (miRNAs) are small non-protein coding RNAs that modulate gene expression after transcription. Few studies have shown that male breast cancer (MBC) shows distinctive miRNAs pattern, suggesting its relevance in this pathology. To study this, we performed a profile of 800 miRNAs in 9 MBC samples and in normal epithelial cells of 3 MBC cases. Experimental Design: Of FFPE tissues, miRNA was extracted for profiles using the NanoString method. miRNAs were obtained by comparing tumor samples versus normal epithelium. Quantitative real-time PCR analyzes were performed by the TaqMan approach for specific miRNAs. Results: The profile of 800 miRNAs showed a different microRNA expression pattern between MBC and its normal counterpart, suggesting a specific microRNA cancer expression profile for MBC. Forty-nine miRNAs showed greater expression, while 26 were found to be down-regulated in MBC, compared to normal tissue. The lower expression of miR-125b correlated significantly with tumors> 2 cm, suggesting that its down-regulation may be implicated in mechanisms to more aggressive tumors. Conclusions: These results suggest that MBC has a unique expression profile compared to normal breast tissue and expression profile of female breast cancer. Differentially expressed miRNAs provide insights of this uncommon but highly aggressive pathology.