miR-217 inhibits triple-negative breast cancer cell growth, migration, and invasion through targeting KLF5.

Triple negative breast cancer (TNBC) is one of the most aggressive breast cancers without effective targeted therapies. Numerous studies have implied that KLF5 plays an important roles in TNBC. How is KLF5 regulated by microRNAs has not been well studied. Here, we demonstrated that miR-217 down-regulates the expression of KLF5 and KLF5's downstream target gene FGF-BP and Cyclin D1 in TNBC cell lines HCC1806 and HCC1937. Consequently, miR-217 suppresses TNBC cell growth, migration, and invasion. MiR-217 suppresses TNBC, at least partially, through down-regulating the KLF5 expression. These results suggest that the miR-217-KLF5 axis might serve as a potential target for treatment of TNBC.