Abstract: Objective To explore the correlation between the expression of miR-488-3p and the clinical features of breast cancer patients, and to promote breast cancer cell invasion, proliferation, migration and cell cycle aggregation in S phase by inhibiting BRCA2. Methods The expression of mir-488-3p in breast cancer tissue samples was detected by RT-qPCR. BRCA2 was tested as a potential target gene for miR-488-3p. The effect of RT-qPCR on mRNA expression of BRCA2 in breast cancer tissues; The protein expression level of BRCA2 in breast cancer tumor tissues was detected by Western blot. OD value of each transfection group was detected by CCK8 assay experiment. The cell ratio of each transfection group at S phase was determined by flow cytometry. Tranwell migration were used to detect the invasion, proliferation, migration and aggregation of MCF7 in breast cancer cell line. A xenograft model of breast cancer xenograft in nude mice was established to detect tumor volume and weight in nude mice. The expression of miR-488-3p in tumor tissues of nude mice transfected with miR-488-3p mimics was detected. Results miR-488-3p was highly expressed in breast cancer tumor tissues. miR -488-3p was also highly expressed in distal metastatic tumor tissues. miR-488-3p was significantly correlated with lymph node metastasis and TNM staging expression（P<0.05）. MRNA translation and protein expression of BRCA2 were inhibited by miR-488-3p. BRCA2 had an inhibitory effect on breast cancer; miR-488-3p can promote the invasion, proliferation, migration and aggregation of MCF7 in breast cancer cells in S phase, and these promoting effects can be inhibited by BRCA2. In nude mice, miR-488-3p promoted the proliferation of MCF7 cells. Conclusion In this study, miR-488-3p inhibiting BRCA2 and promoting breast cancer proliferation may be a new target for breast cancer diagnosis and treatment.

Key words: breast cancer, miR-488-3p, BRCA2