Objective  To investigate the effect of miRNA-34b/c-5p on the expression of neurokinin 1 receptor-truncated (NK1R-Tr) in breast cancer and the effect of miRNA-34b/c-5p and NK1R-Tr on the migration and invasion abilities of breast cancer cells.

  Methods  Real-time fluorescence quantitative PCR (RT-PCR) was used to detect the expression of miRNA-34b/c-5p and NK1R-Tr in 50 breast cancer specimens that were collected at Tianjin Medical University Cancer Institute & Hospital from February to May 2013. Western blot analysis was performed to detect the expression of miRNA-34b/c-5p and NK1R-Tr in breast cancer cell lines MDA-MB-231 and MCF-7. Scratch and Transwell assays were carried out to explore the effects of miRNA-34b/c-5p and NK1R-Tr on the migration and invasion abilities of MDA-MB-231 cells.

  Results  The expression of miRNA-34b/c-5p and NK1R-Tr in breast cancer tissues and cells were significantly negatively correlated. The relative expression of NK1R-Tr in breast cancer patients with lymph node metastasis was 5.75, and the relative expression of NK1R-Tr in patients with non-lymph node metastasis was 4.29. The relative expression was significantly different between the two groups (P=0.026). Overexpression of miRNA-34b/c-5p and knockdown of NK1R-Tr could significantly inhibit the migration and invasion abilities of MDA-MB-231 cells (all P < 0.001).

  Conclusions  The expression of miRNA-34b/c-5p and NK1R-Tr was significantly negatively correlated. MiRNA-34b/c-5p and NK1R-Tr might be potential therapeutic targets for inhibiting the invasion of breast cancer cells.