Fold change levels from gene expression analyses of DEP domain containing 1 (DEPDC), Forkhead box M1 (FOXM1), and Lim domain only 4 (LM04). Control group is compared with treated group at 12 and 24 hours.
Instituto de Salud Carlos III
ACEPAIN; AMAC, Diputación de Albacete and CRIS Cancer Foundation
Ministry of Economy and Competitiveness of Spain
ARTICLE ABSTRACTTriple-negative breast cancer (TNBC) is an incurable disease with poor prognosis. At this moment, therapeutic options are limited to chemotherapy, and no targeted agent has reached the clinical setting. Bromodomain and extraterminal (BET) inhibitors are a new family of compounds that inhibit bromodomain-containing proteins affecting the expression of transcription factors, therefore modifying the expression of relevant oncogenic genes. In the present article, by using an in silico approach, we have identified the expression of upregulated transcription factors in TNBC compared with normal breast. Treatment with JQ1, a well-characterized BET inhibitor, modified some transcription factors, including DEP domain containing 1 (DEPDC), Forkhead box M1 (FOXM1), and Lim domain only 4 (LM04). In cell line models, administration of JQ1 or OTX015, another BET inhibitor, produced a significant antiproliferative effect and synergized with chemotherapies. Biochemical evaluation demonstrated an arrest at G1 as the main mechanism of action with a clear increase of p27. Addition of these compounds to chemotherapy induced apoptosis compared to each agent given alone. Evaluation of JQ1 in xenografted tumors in nude mice showed a profound antitumoral effect with a reduction of DEPDC, FOXM1, and LM04, in addition to an increase of p27. Globally, our data demonstrate the antitumor effect of this new family of compounds in TNBC, paving the way for its future clinical development. Mol Cancer Ther; 15(8); 1823–33. ©2016 AACR.