Abstract 5029: Upregulation of miRNA27, miRNA125a and 125b in ERalpha-negative breast cancers

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL MicroRNAs (miRNAs) are a major class of small endogenous RNA molecules that post-transcriptionally inhibit gene expression. Many miRNAs have been implicated in the human breast cancer. We show here the correlation between breast cancer types characterized upon histological and immunohistochemical analysis and miRNA expression in 22 Polish patients. The group was divided into three categories: ERalpha-negative / ERalpha-positive, HER2-negative / HER2-positive and lymph node -negative / lymph node -positive (N-/N+) cases. Surgically removed tumors were congealed in liquid nitrogen and subsequently small RNA was extracted. We investigated the level of miR-17-5p, miR-27, miR-125a, miR-125b and miR-206 using real-time PCR TaqMan probes. Let-7 miRNA and U6 RNA were used as reference genes. We observed upregulation of the subsequent suppressor miRNAs miR-27, miR-125a and 125b in ERalpha-negative tumors (p<0.05). Comparison of expression of miR-17-5p, miR-27, miR-125a, miR-125b and miR-206 in N- and N+ samples did not reveal any significant differences. We also observed a tendency to lower level of expression of all investigated miRNAs in HER2-positive patients in comparison with HER2-negative. We concluded that miR-27, miR-125a and miR-125b may play an important role in the regulation of ER-alpha expression in breast cancer cells. They could also be regarded as surrogate markers of ER-alpha -negativity. However, the small number of patients included to the study warrants further investigation in the larger cohort of breast cancer patients. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5029. doi:1538-7445.AM2012-5029