Breast cancer (BC) is a common malignant tumor in women, and a considerable number of studies show that aberrant expression of miRNA is correlated with BC development. By analyzing TCGA-BRCA database through bioinformatics method, this study disclosed that miR-337−3p was significantly low in BC tissue and might be a cancer inhibitor in BC. To explore the effect and potential mechanism of miR-337−3p in BC, qRT-PCR was used in this study to indicate that the expression of miR-337−3p was downregulated in BC cells. Then, the effects of miR-337−3p on BC cells were detected by western blot, Cell Counting Kit-8 (CCK-8), wound healing and Transwell assays. After upregulating miR-337−3p expression, the cell viability, migration, invasion and epithelial-mesenchymal transition (EMT) of BC cells were markedly inhibited while cell apoptosis remarkably increased. Besides, it was predicted and identified by bioinformatics analysis and dual-luciferase assay that ESRP1 was a target gene of miR-337−3p. Finally, the progression and EMT of BC cells were promoted after upregulating ESRP1 expression level. However, upregulating miR-337−3p as well as ESRP1 reduced the promotion on the malignant phenotype of BC cells. This result revealed that miR-337−3p could inhibit ESRP1 expression to perform its biological functions. In conclusion, it was illustrated in this study that miR-337−3p is a tumor-inhibitor of BC and plays its regulatory role via its downstream gene ESRP1.

乳腺癌（BC）是女性常见的恶性肿瘤，大量研究表明miRNA的异常表达与乳腺癌的发生发展相关。本研究通过生物信息学方法分析TCGA-BRCA数据库，发现miR-337-3p在BC组织中显着降低，可能是BC中的癌症抑制剂。为了探索 miR-337-3p 在 BC 中的作用和潜在机制，本研究使用 qRT-PCR 表明 miR-337-3p 在 BC 细胞中的表达下调。然后，通过蛋白质印迹、Cell Counting Kit-8 (CCK-8)、伤口愈合和 Transwell 试验检测 miR-337-3p 对 BC 细胞的影响。上调 miR-337−3p 表达后，细胞活力、迁移、BC细胞的侵袭和上皮-间质转化(EMT)明显受到抑制，而细胞凋亡明显增加。此外，通过生物信息学分析和双荧光素酶分析预测和鉴定ESRP1是miR-337-3p的靶基因。最后，上调ESRP1表达水平后，促进了BC细胞的进展和EMT。然而，上调 miR-337-3p 和 ESRP1 降低了对 BC 细胞恶性表型的促进作用。该结果表明 miR-337-3p 可以抑制 ESRP1 表达以发挥其生物学功能。总之，本研究表明 miR-337-3p 是 BC 的肿瘤抑制剂，通过其下游基因 ESRP1 发挥调节作用。通过生物信息学分析和双荧光素酶分析预测和鉴定ESRP1是miR-337-3p的靶基因。最后，上调ESRP1表达水平后，促进了BC细胞的进展和EMT。然而，上调 miR-337-3p 和 ESRP1 降低了对 BC 细胞恶性表型的促进作用。该结果表明 miR-337-3p 可以抑制 ESRP1 表达以发挥其生物学功能。总之，本研究表明 miR-337-3p 是 BC 的肿瘤抑制剂，通过其下游基因 ESRP1 发挥调节作用。通过生物信息学分析和双荧光素酶分析预测和鉴定ESRP1是miR-337-3p的靶基因。最后，上调ESRP1表达水平后，促进了BC细胞的进展和EMT。然而，上调 miR-337-3p 和 ESRP1 降低了对 BC 细胞恶性表型的促进作用。该结果表明 miR-337-3p 可以抑制 ESRP1 表达以发挥其生物学功能。总之，本研究表明 miR-337-3p 是 BC 的肿瘤抑制剂，通过其下游基因 ESRP1 发挥调节作用。该结果表明 miR-337-3p 可以抑制 ESRP1 表达以发挥其生物学功能。总之，本研究表明 miR-337-3p 是 BC 的肿瘤抑制剂，通过其下游基因 ESRP1 发挥调节作用。该结果表明 miR-337-3p 可以抑制 ESRP1 表达以发挥其生物学功能。总之，本研究表明 miR-337-3p 是 BC 的肿瘤抑制剂，通过其下游基因 ESRP1 发挥调节作用。