Department of Medical Biology, Medical Faculty, Uludag University, Turkey
Background: Dysregulation of miRNA expression may be used as a biomarker for specific tumours because it may contribute to development of cancer. Circulating miRNA profiles have been highlighted for their potential as predictive markers in heterogeneous diseases such as breast cancer. In the literature, there is evidence that miR-195 levels are differentially expressed pre- and post-operative periods in breast cancer patients. At the same time, miRNA expression levels may vary because of ethnic origins. This study aimed to determine expression levels and potential roles of miR-195 in Turkish breast cancer patients. Materials and Methods: The expression patterns of miR-195 were initially examined in breast cancer tissues (luminal A and B type) (n96). Subsequently, blood samples were prospectively collected from preoperative and postoperative Turkish breast cancer patients and disease free controls. Total RNA was isolated, and the expression level of miR-195 was quantified by real-time PCR. Results: We found that miR-195 level was altered in Turkish breast cancer patients, with down-regulation evident in breast cancer tissues compared to normal adjacent specimens. Furthermore, circulating levels of miR- 195 was significantly decreased in post-operative blood samples compared with pre-operative levels (p0.01 and <0.05). However, miR-195 was significantly increased in pre-operative blood samples of the luminal B type (p 0.04 and <0.05). Conclusions: This study represents the first report of a miR-195 expression profile in Turkish breast cancer patients. Our data suggests that miR-195 levels might be a clinically useful biomarker in the earliest stage of Turkish breast cancer patients.