Dark Sweet Cherry (Prunus avium) Anthocyanins Inhibited the Growth and Biomarkers for Breast Cancer Growth and Invasion in Highly Metastatic 4T1 Tumor Cells

To investigate the mechanisms underlying the breast cancer anti-invasive activity of DSC phenolics enriched in anthocyanins (ACN) in vitro and their potential in vivo. 4T1 cells were treated with ACN extracted from DSC concentrate juice (FruitSmart, Grandview, WA) within dose range 20–80 µg cyanidin 3-glucoside equivalent (C3G)/mL to assess reactive oxygen species (ROS) levels using carboxy-H2DFFDA probe and cell viability using the resazurin kit (Sigma-Aldrich, St Louis, MO). Protein and mRNA expression were investigated using standard procedures and cell migration by wound healing assay. The pilot in vivo study was performed with 4T1 cells orthotopically injected into mammary fat pads of BALB/c mice (Envigo, Houston, TX, USA) (n = 4). After tumor growth, animals were gavaged with ACN (150 mg C3G/kg body weight/day, n = 2) or saline solution (control, n = 2) for one week followed by euthanasia and collection of tumors, lungs, and liver tissues for analyses. ACN induced ROS production (up to 5.13-fold of control) and inhibited cell viability by 50% (IC50) at 58.6 µg C3G/mL. The ACN (IC50 dose) treatment downregulated phospho-ERK1/2 and upregulated phospho-p38 proteins, linked to cell growth inhibition and caspase-dependent apoptosis mediated by the increase in cleaved/total caspase-3 protein ratio (∼3-fold of control) and suppression of total PARP (∼0.4-fold of control). ACN also suppressed the Akt/mTOR/CREB pathway that promotes proliferation and invasion. 4T1 cell migration was inhibited by 22%, consistent with the phospho-Src downregulation (down to ∼ 0.25-fold of control), that regulate epithelial-mesenchymal transition. Phospho-ERK1/2 and phospho-CREB were downregulated in mice tumors. This was accompanied by the downregulation of Cenpf mRNA in liver and lungs, which correlates with poor prognosis and metastasis, thus supporting the in vitro findings. ACN provides a dietary alternative to fight human breast cancer invasion by incorporating DSC into the diet. More studies are guarantee to help improve the quality of life of breast cancer patients. This work was supported by the Northwest Cherry Growers. The authors thank the support of Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Brazil for providing Ana Carolina Silveira Rabelo the scholarship.