Breast cancer is the most frequent cancer and the leading cause of cancer death in women. Oxidative stress and the generation of reactive oxygen species (ROS) have been related to cancer progression. Compared to their normal counterparts, tumor cells show higher ROS levels and tight regulation of REDOX homeostasis to maintain a low degree of oxidative stress. Traditionally antioxidants have been extensively investigated to counteract breast carcinogenesis and tumor progression as chemopreventive agents; however, there is growing evidence indicating their potential as adjuvants for the treatment of breast cancer. Aimed to elucidate whether antioxidants could be a reality in the management of breast cancer patients, this review focuses on the latest investigations regarding the ambivalent role of antioxidants in the development of breast cancer, with special attention to the results derived from clinical trials, as well as their potential use as plausible agents in combination therapy and their power to ameliorate the side effects attributed to standard therapeutics. Data retrieved herein suggest that antioxidants play an important role in breast cancer prevention and the improvement of therapeutic efficacy; nevertheless, appropriate patient stratification based on “redoxidomics” or tumor subtype is mandatory in order to define the dosage for future standardized and personalized treatments of patients.

On the basis of the identified stress-independent cellular functions of activating transcription factor 4 (ATF4), we reported enhanced ATF4 levels in MCF10A cells treated with TGFβ1. is overexpressed in patients with triple-negative breast cancer (TNBC), but its impact on patient survival and the underlying mechanisms remain unknown. We aimed to determine effects on patients with breast cancer survival and TNBC aggressiveness, and the relationships between TGFβ and ATF4. Defining the signaling pathways may help us identify a cell signaling-tailored gene signature. Patient survival data were determined by Kaplan-Meier analysis. Relationship between TGFβ and ATF4, their effects on aggressiveness (tumor proliferation, metastasis, and stemness), and the underlying pathways were analyzed in three TNBC cell lines and using patient-derived xenografts (PDX). overexpression correlated with TNBC patient survival decrease and a SMAD-dependent crosstalk between ATF4 and TGFβ was identified. expression inhibition reduced migration, invasiveness, mammosphere-forming efficiency, proliferation, epithelial-mesenchymal transition, and antiapoptotic and stemness marker levels. In PDX models, silencing decreased metastases, tumor growth, and relapse after chemotherapy. ATF4 was shown to be active downstream of SMAD2/3/4 and mTORC2, regulating TGFβ/SMAD and mTOR/RAC1-RHOA pathways independently of stress. We defined an eight-gene signature with prognostic potential, altered in 45% of 2,509 patients with breast cancer. ATF4 may represent a valuable prognostic biomarker and therapeutic target in patients with TNBC, and we identified a cell signaling pathway-based gene signature that may contribute to the development of combinatorial targeted therapies for breast cancer. .

Purpose This study was aimed to determine the impact of hydroxytyrosol (HT), a minor compound found in olive oil, on breast cancer stem cells (BCSCs) and the migration capacity of triple-negative breast cancer (TNBC) cell lines through the alteration of epithelial-tomesenchymal transition (EMT) and embryonic signaling pathways. MethodsBCSCs self-renewal was determined by the mammosphere-forming efficiency in SUM159PT, BT549, MDA-MB-231 and Hs578T TNBC cell lines. Flow cytometric analysis of CD44 + /CD24 -/low and aldehyde dehydrogenase positive (ALDH + ) subpopulations, migration by the "wound healing assay", invasion and western blot of EMT markers and TGFβ signaling were investigated in SUM159PT, BT549 and MDA-MB-231 cell lines. Wnt/β-catenin signaling was assessed by western blot in BT549 cells expressing WNT1 and MDA-MB-231 cells. Changes in TGFβ activity was determined by SMAD Binding Element (SBE) reporter assay. Results HT reduced BCSCs self-renewal, ALDH + (aldehyde dehydrogenase) and CD44 + /CD24 -/low subpopulations, tumor cell migration and invasion. Consistently, HT suppressed Wnt/βcatenin signaling by decreasing p-LRP6, LRP6, β-catenin and cyclin D1 protein expression and the EMT markers SLUG, ZEB1, SNAIL and VIMENTIN. Finally, HT inhibited p-SMAD2/3 and SMAD2/3 in SUM159PT, BT549 and MDA-MB-231 cells, what was correlated with a less TGFβ activity. Conclusion In conclusion, we report for the first time the inhibitory role of HT on BCSCs and tumor cell migration by targeting EMT, Wnt/β-catenin and TGFβ signaling pathways. Our findings highlight the importance of the chemopreventive compound HT as a novel candidate to be investigated as an alternative targeted therapy for TNBC.4