miR-199b-5p inhibits triple negative breast cancer cell proliferation, migration and invasion by targeting DDR1.

Triple negative breast cancer (TNBC) has received increasing attention from oncologists worldwide due to its poor prognosis and paucity of targeted therapies. MicroRNAs (miRs) are a group of small non-coding RNAs that are responsible for the post-transcriptional regulation of various target genes. The present study demonstrated that the expression of miR-199b-5p in breast cancer tissue was significantly reduced compared with that in normal breast tissues by reverse transcription-quantitative polymerase chain reaction. In addition, western blot analysis and luciferase reporter assays revealed that miR-199b-5p in TNBC cells inhibited discoidin domain receptor tyrosine kinase 1 expression by directly targeting its 3'-untranslated region. Furthermore, miR-199b-5p markedly suppressed the proliferation and invasion of TNBC cells, as demonstrated by using wound-healing, migration, invasion and proliferation assays. Collectively, these results indicate that miR-199b-5p may be a novel alternative therapeutic target for TNBC.