MicroRNA-223 Targeting STIM1 Inhibits the Biological Behavior of Breast Cancer

To investigate the cellular effects and clinical significance of microRNA-223 (miR-223) in breast cancer by targeting stromal interaction molecule1 (STIM1).

Breast cancer cell lines (T47D, MCF-7, SKB-R3, MDA-MB-231 and MDA-MB-435) and a normal breast epithelial cell line (MCF-10A) were prepared for this study. MiR-223 mimics, anti-miR-223 and pcDNA 3.1-STIM1 were transiently transfected into cancer cells independently or together, and then RT-qPCR was performed to detect the expressions of miR-223 and STIM1 mRNA, dual-luciferase reporter assay was conducted to examine the effects of miR-223 on STIM1, Western blotting was used to measure the expressions of the STIM1 proteins, MTT and Trans-well assays were performed to detect cell proliferation and invasion. Finally, the correlation of miR-223 and STIM1 was investigated by detecting with ISH and IHC in breast cancer specimens or the corresponding adjacent normal tissues.

Compared with normal cells and tissues, breast cancer tissues and cells exhibited significantly lower expression of miR-223, but higher expression of STIM1. MiR-223 could inhibit the proliferation and invasiveness of breast cancer cells by negatively regulating the expressions of STIM1. Reimplantation with STIM1 partially rescued the miRNA-223-induced inhibition of breast cancer cells. Clinical data revealed that high expression of STIM1 and miR-223 was respectively detrimental and beneficial factor impacting patient's disease-free survival (DFS) rather than overall survival (OS). Moreover, Pearson correlation analysis also confirmed that STIM1 was inversely correlated with miR-223.

MiR-223 inhibits the proliferation and invasion of breast cancer by targeting STIM1. The miR-223/STIM1 axis could possibly be a potential therapeutic target for treating breast cancer patients.