miR-155 expression level changes might be associated with initial phases of breast cancer pathogenesis and lymph-node metastasis
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BACKGROUND: Breast carcinoma is heterogeneous disease. Understanding the process of invasion and metastasis and the selection of the therapy for patients with breast carcinomas still remains difficult. MicroRNAs are powerful gene expression regulators. Because of inconsistent findings, we have analyzed potential difference in miR-155 levels in three breast cancer groups. OBJECTIVES: Our goals were to examine miR-155 expression levels in normal tissue, non-invasive and invasive breast carcinomas, and their association with standard clinical and pathological parameters and oncomiR-21, and to investigate the ability of miR-155 to separate invasive breast carcinomas with non-invasive component from pure invasive. METHODS: In the group of 40 breast tissue samples, relative expression levels of miR-155 were examined with stem-loop quantitative real-time PCR using TaqMan technology. RESULTS: The significant difference among four examined groups of the breast tissue was detected (p = 0.001). I...n the group of pure invasive tumors, patients with positive nodal status had significantly higher miR-155 levels (p = 0.046). CONCLUSION: Our results suggest that miR-155 might be involved in breast cancer pathogenesis and in tumor spreading to the lymph nodes, and that it might be used as biomarker for additional stratification of patients with invasive breast carcinomas with non-invasive component.