Decoy-DNA against special AT-rich sequence binding protein 1 inhibits the growth and invasive ability of human breast cancer.

"Triple-negative" (TN) breast cancers, which are characterized by estrogen receptor (-), progesterone receptor (-), and human epidermal growth factor receptor 2 (-), are typically associated with poor prognosis because of their aggressive tumor phenotypes. In recent years, the number of patients with breast cancers has remarkably increased, but there are only few available drugs for treatment of TN breast cancers. The development of novel drugs targeting TN breast cancer is urgently required. In the present study, we focused on the function of special AT-rich sequence binding protein 1 (SATB1) as a target molecule for the treatment of TN breast cancers. By recruiting chromatin remodeling enzymes and transcriptional factors, SATB1 regulates the expression of >1,000 genes related to cell growth and translocation. We synthesized a decoy DNA against SATB1, including the recognition sequence of SATB1. We examined the inhibitory effects of the decoy DNAs on cellular proliferation of a TN metastatic breast cancer cell line (MDA-MB-231). SATB1-decoy DNA inhibited the proliferation of MDA-MB-231 cells. Especially, it was significant that SATB1-decoy DNA drastically reduced the invasive and metastatic capacity of MBA-MB-231 cells. Further, in the case of MCF7 cells (SATB1-negative breast cancer cell line), SATB1-decoy DNA did not exhibit any inhibitory effect. These data suggest that SATB1-decoy DNA may be an effective candidate for use as a molecular-targeting drug for treatment of TN breast cancer.