Abstract
The RUNX2 transcription factor promotes breast cancer growth and metastasis through interactions with a variety of cofactors that activate or repress target genes. Using a direct drug discovery approach we identified CADD522 as a small molecule that inhibits the DNA binding of the runt box domain protein, RUNX2. The current study defines the effect of CADD522 on breast cancer growth and metastasis, and addresses the mechanisms by which it exerts its anti-tumor activity.CADD522 treatment resulted in significant growth inhibition, clonogenic survival, tumorsphere formation, and invasion of breast cancer cells. CADD522 negatively regulated transcription of RUNX2 target genes such as matrix metalloproteinase-13, vascular endothelial growth factor and glucose transporter-1, but upregulated RUNX2 expression by increasing RUNX2 stability. CADD522 reduced RUNX2-mediated increases in glucose uptake and decreased the level of CBF-β and RUNX2 phosphorylation at the S451 residue. These results suggest several potential mechanisms by which CADD522 exerts an inhibitory function on RUNX2-DNA binding; interference with RUNX2 for the DNA binding pocket, inhibition of glucose uptake leading to cell cycle arrest, down-regulation of CBF-β, and reduction of S451-RUNX2 phosphorylation.The administration of CADD522 into MMTV-PyMT mice resulted in significant delay in tumor incidence and reduction in tumor burden. A significant decrease of tumor volume was also observed in a CADD522-treated human triple-negative breast cancer-patient derived xenograft model. CADD522 impaired the lung retention and outgrowth of breast cancer cells in vivo with no apparent toxicity to the mice. Therefore, by inhibiting RUNX2-DNA binding, CADD522 may represent a potential antitumor drug.
Highlights
Despite recent advances in treatment, breast cancer (BC) still remains the second leading cause of cancerrelated deaths among women [1]
CADD522 reduced RUNX2mediated increases in glucose uptake and decreased the level of Core binding factor (CBF)-β and runt-box domain protein-2 (RUNX2) phosphorylation at the S451 residue. These results suggest several potential mechanisms by which CADD522 exerts an inhibitory function on RUNX2-DNA binding; interference with RUNX2 for the DNA binding pocket, inhibition of glucose uptake leading to cell cycle arrest, down-regulation of CBF-β, and reduction of S451-RUNX2 phosphorylation
We performed DNA-binding ELISA (D-ELISA) with MMP13 oligonucleotides designed from the promoter sequences near the Runt binding site, and found that CADD522 inhibited RUNX2 binding to the MMP13 oligonucleotides in a dose-dependent manner (Supplementary Figure 1C)
Summary
Despite recent advances in treatment, breast cancer (BC) still remains the second leading cause of cancerrelated deaths among women [1]. Luminal BC has the highest rates of relapse, often localizes to the bone or lung [2, 3] and accounts for 50% of all metastasis-related BC deaths in spite of the primary tumor being highly responsive to treatment [4]. Given their high rate of relapse, it is clear that current treatment modalities are insufficient to completely eradicate these heterogeneous tumors. Because of no useful biomarkers and no targeted therapeutic modalities for metastatic disease, treatment options for patients with TNBC are limited to cytotoxic chemotherapy. There is an urgent need to elucidate novel targets for BC therapy to improve the poor prognosis for patients
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
