miR-140-3p inhibits breast cancer proliferation and migration by directly regulating the expression of tripartite motif 28.

The present study aimed to determine the expression profile and significance of microRNA-140-3p (miR-140-3p) in breast cancer (BC). miR-140-3p expression in BC tumor tissues and cell lines was measured by reverse transcription-quantitative polymerase chain reaction. Luciferase activity reporter assay and western blotting were used to assess the effect of miR-140-3p expression on tripartite motif 28 (TRIM28). Cell growth, migration, and invasion were assessed by Cell Counting Kit-8 assay, wound-healing assay and Transwell invasion assay, respectively. miR-140-3p expression was significantly reduced in BC tumor tissues compared with in adjacent normal tissues. Additionally, low miR-140-3p expression was found to predict poor prognosis of patients with BC. TRIM28 expression was significantly reduced by miR-140-3p overexpression in BC cell lines, and was inversely correlated with miR-140-3p in BC tissues. Overexpression of miR-140-3p also inhibited cell proliferation, migration and invasion compared with in the control group. In conclusion, the present study revealed that miR-140-3p inhibited the progression of BC partially by regulating TRIM28.