[Effects of miR-203a targeting and its target gene on lymph node metastasis of breast cancer]

Objective: To study the expression and correlation of mir-203a and its target gene ATM in breast cancer tissues, so as to provide theoretical basis for the pathogenesis of breast cancer, especially lymph node metastasis. Methods: Thirty paired breast cancer and paracancer normal tissues were collected, and RT-qPCR was used to detect the relative expression levels of mir-203a and ATM in the samples of the two groups. Correlation analysis was conducted for mir-203a and ATM, and correlation analysis was conducted for the pathological characteristics, so as to compare whether there were statistical differences between mir-203a and ATM in lymph node metastasis and non-metastasis. Results: Compared with normal paracancer tissues, the expression level of mir-203a in breast cancer tissues was significantly increased (P＜0.01), and the expression level of ATM was significantly decreased (P＜0.01), showing a significant negative correlation between the two tissues (r=-0.847,P＜0.01).The expression level of mir-203a and ATM was significantly correlated with lymph node metastasis and different clinical stages (P＜0.05). The expression level of mir-203a in the group with lymph node metastasis were significantly lower than that in the group without lymph node metastasis (P＜0.05), and the expression of ATM in the group with lymph node metastasis was significantly higher than that in the group without lymph node metastasis (P＜0.01). Conclusion: The overexpression of mir-203a in the early stage of breast cancer may inhibit the expression of its target gene ATM, which may be a protective mechanism to regulate the proliferation,metastasis and invasiveness of tumor cells. In the middle and late stage, mir-203a is down-regulated and the ATM gene is up-regulated, which may be involved in lymph node metastasis.