Expression profile of miR-155 and miR-34a in peripheral blood and tissues of breast cancer patients

Breast cancer severely affects women’s health. The role of microRNA (miR) in the pathological process of tumors has been widely studied as one novel biological marker for diagnosis, typing and prognosis. Previous study has suggested the correlation between breast cancer and miR. This study thus investigated expression level of miR-155 and miR-34a in both blood and tissue samples from breast cancer patients, thus investigating their relationships with tumor occurrence and potential values in early diagnosis and prognosis prediction. A total of 40 breast cancer patients who received surgeries in our hospital were recruited as the experimental group, in parallel with 40 healthy controls. RT-PCR was used to test the expression of miR-155 and miR-34a level in blood samples, and tumor or adjacent tissues. Correlation analysis was performed regarding their expression level and pathological features of tumors. Blood samples of cancer patients had higher miR-155 and lower miR-34a compared to control group (P<0.05). Breast cancer tissue had higher miR-155 and lower miR-34a than adjacent tissues (P<0.05). The expression of miR-155 and miR-34a is correlated with TNM stage, lymph node metastasis and differentiation degree (P<0.05). With advanced TNM stage, lymph node metastasis, and lower differentiation grade, miR-34a was up-regulated while miR-155 was down-regulated. MiR-155 expression was increased and miR-34a was downregulated in breast cancer patients. Their expression level is related with TNM stage, lymph node metastasis and differentiation grade. Both miR-155 and miR-34a might participate in the occurrence, progression, infiltration and metastasis of breast cancer.