Objective:To examine the level of expression of microRNA-21(miR-21) in breast cancer and its adjacent non-cancerous tissues, and analyze the miR-21 expression with the clinicopathological factors of breast cancer.
Methods:Specimens of breast cancer and adjacent tissues were collected from 60 patients. Their miR-21 expression was detected by Stem-loop real-time RT-PCR, and levels of miR-21 expression in tumor size, TNM clinical stage, histology, lymph node involvement, and hormone receptor status were compared.
Results:High sensitivity, specificity and precision of Stem-loop real-time RT-PCR allowed for direct analysis of expression of miR-21 in breast cancer tissues and adjacent tissues. The expression of miR-21 in breast cancer tissues was markedly higher than in adjancent tissue （P＜0.001). Elevated miR-21 expression was also positively correlated with advanced TNM stage, lymph node metastasis, and low PR levels（P=0.007,0.001,and 0.012 respectively）. Moreover, the levels of expression of miR-21 in triple-negative breast cancer（TNBC）were higher than those in non-TNBC types（P=0.029）.
Conclusions:High levels of expression of miR-21 are correlated with degree of malignancy of breast cancer.