As a new type of nanomaterial, DNA nanomaterials show great potential in biomedical applications because of their high precision, high controllability, and high biocompatibility among other characteristics. Therapeutic drugs based on DNA nanomaterials have been shown to have beneficial therapeutic effects on a variety of diseases. The application of DNA nanomedicines in the treatment of diseases has become a rapidly developing area of study. However, the instability of DNA nanomaterials greatly limits their clinical application. Therefore, we designed and synthesized a stable topological DNA nanostructure: DNA Nano Trihedron (DNT). We demonstrated that DNT could enter MCF-7 cells without the transfection agent. In addition, DNT could induce dramatic changes in gene expression and produce significant inhibitory effects on MCF-7 cells. DNT after two months of storage still had an inhibitory effect on MCF-7 cells.