Antiproliferative Modulation and Pro-Apoptotic Effect of BR2 Tumor-Penetrating Peptide Formulation 2-Aminoethyl Dihydrogen Phosphate in Triple-Negative Breast Cancer

SIMPLE SUMMARY: Triple-negative breast cancer (TNBC) is an aggressive, hard-to-treat form of breast cancer, accounting for about 15 percent of breast cancers. The aim of our study was to assess the potential added value of combining monophosphoester 2-aminoethyl dihydrogen phosphate (2-AEH(2)P), a molecule involved in phospholipid turnover with antiproliferative and pro-apoptotic properties toward cancer cells, and the antitumor BR2 cell-penetrating peptide for TNBC treatment. Using an array of TNBC cells, our data demonstrate that, while possessing limited anti-cancer properties when used as single agents, a drastic synergy was observed with the association 2-AEH(2)P+BR2. Mechanistically, the 2-AEH(2)P+BR2 combination acts by inducing TNBC cells, but not normal cells, apoptosis and by preventing their migration potential through the modulation of cell death-related proteins, reduction of the mitochondrial potential and intracellular redistribution of important components such as the cytoskeleton. Our observations provide a clear rationale for the association of 2-AEH(2)P with the BR2 peptide as a new TNBC treatment. ABSTRACT: Breast cancer is the most common cancer in women, the so-called “Triple-Negative Breast Cancer” (TNBC) subtype remaining the most challenging to treat, with low tumor-free survival and poor clinical evolution. Therefore, there is a clear medical need for innovative and more efficient treatment options for TNBC. The aim of the present study was to evaluate the potential therapeutic interest of the association of the tumor-penetrating BR2 peptide with monophosphoester 2-aminoethyl dihydrogen phosphate (2-AEH(2)P), a monophosphoester involved in cell membrane turnover, in TNBC. For that purpose, viability, migration, proliferative capacity, and gene expression analysis of proteins involved in the control of proliferation and apoptosis were evaluated upon treatment of an array of TNBC cells with the BR2 peptide and 2-AEH(2)P, either separately or combined. Our data showed that, while possessing limited single-agent activity, the 2-AEH(2)P+BR2 association promoted significant cytotoxicity in TNBC cells but not in normal cells, with reduced proliferative potential and inhibition of cell migration. Mechanically, the 2-AEH(2)P+BR2 combination promoted an increase in cells expressing p53 caspase 3 and caspase 8, a reduction in cells expressing tumor progression and metastasis markers such as VEGF and PCNA, as well as a reduction in mitochondrial electrical potential. Our results indicate that the combination of the BR2 peptide with 2-AEH(2)P+BR2 may represent a promising therapeutic strategy in TNBC with potential use in clinical settings.