Ethanol extract of propolis and its constituent caffeic acid phenethyl ester inhibit breast cancer cells proliferation in inflammatory microenvironment by inhibiting TLR4 signal pathway and inducing apoptosis and autophagy

Abstract

BackgroundPropolis and its major constituent – caffeic acid phenethyl ester (CAPE) have good abilities on antitumor and anti-inflammation. However, little is known about the actions of propolis and CAPE on tumor in inflammatory microenvironment, and inflammatory responses play decisive roles at different stages of tumor development. To understand the effects and mechanisms of ethanol-extracted Chinese propolis (EECP) and its major constituent - CAPE in inflammation-stimulated tumor, we investigated their effects on Toll-like receptor 4 (TLR4) signaling pathway which plays a crucial role in breast cancer MDA-MB-231 cell line.Methods80% confluent breast cancer MDA-MB-231 cells were stimulated with 1 μg/mL lipopolysaccaride (LPS). Then the cells were divided for treatment by CAPE (25 μg/mL) and EECP (25, 50 and 100 μg/mL), respectively. Cell viability, nitric oxide (NO) production and cell migration were measured by sulforhodamine B assay, chemical method and scratch assay. The levels of TLR4, MyD88, IRAK4, TRIF, caspase 3, PARP, LC3B and p62 were investigated through western blotting. The expression of TLR4, LC3B and nuclear factor-κB p65 (NF-κB p65) were tested by immunofluorescence microscopy assay.ResultsTreatment of different concentrations of EECP (25, 50 and 100 μg/mL) and CAPE (25 μg/mL) significantly inhibited LPS-stimulated MDA-MB-231 cell line proliferation, migration and NO production. Furthermore, EECP and CAPE activated caspase3 and PARP to induce cell apoptosis, and also upregulated LC3-II and decreased p62 level to induce autophagy during the process. TLR4 signaling pathway molecules such as TLR4, MyD88, IRAK4, TRIF and NF-κB p65 were all down-regulated after EECP and CAPE treatment in LPS-stimulated MDA-MB-231 cells.ConclusionsThese findings indicated that EECP and its major constituent - CAPE inhibited breast cancer MDA-MB-231 cells proliferation in inflammatory microenvironment through activating apoptosis, autophagy and inhibiting TLR4 signaling pathway. EECP and CAPE may hold promising prospects in treating inflammation-induced tumor.

Theaflavins attenuate ethanol‑induced oxidative stress and cell apoptosis in gastric mucosa epithelial cells via downregulation of the mitogen‑activated protein kinase pathway

“…ROS are involved in cell oxidative stress mechanisms, predominantly via the induction of lipid peroxidation in the phospholipid membrane, the production of oxygen radicals and the induction of cell apoptosis ( 26 , 27 ). Antioxidant enzymes, such as SOD and GSH, eliminate ROS to maintain the balance of ROS generation and elimination during cell normal metabolism ( 45 , 46 ).…”

“…In addition to the role of oxidative stress, studies have indicated that the underlying molecular mechanisms of ethanol-induced gastric diseases may involve multiple signaling pathways, including apoptosis and mitogen-activated protein kinase (MAPK) pathways, such as extracellular signal-regulated kinase (ERK)1, ERK2, c-Jun N-terminal kinase (JNK) and p38 kinase (p38) MAPK pathways ( 26 , 27 ). Apoptosis is induced by oxidative stress and the subsequent increases in superoxide and hydroxyl radicals, and MAPK pathways have important roles in cell proliferation, differentiation and apoptosis.…”

Chemopreventive Effects of Propolis in the MNU-Induced Rat Mammary Tumor Model

“…A recent paper sustains that caffeic acid phenethyl ester is rather most efficient than caffeic acid, inducing cell cycle arrest in S phase and triggering apoptosis in the triple-negative human Caucasian breast adenocarcinoma line cells (MDA-MB-231) [20]. In a similar report, caffeic acid phenethyl ester inhibited breast cancer MDA-MB-231 cells proliferation, activating apoptosis and autophagy, and inhibiting TLR4 signaling pathway [21]. The antiproliferative and proapoptotic activity of Lebanese propolis was demonstrated on breast adenocarcinoma MDA-MB-231 cells, Jurkat leukemic T-cells and glioblastoma U251 cells [16].…”

A Great Concern Regarding the Authenticity Identification and Quality Control of Chinese Propolis and Brazilian Green Propolis

“…It has been demonstrated that CAPE can cause acetylated histones accumulation in MDA-MB-231 (ER-/PR-/Her2-) and MCF-7 (ER+) cells, which is associated with up-regulated ER and downrelulated EGFR in MDA-MB-231 cells and decreased ER and PR in MCF-7 cells. This evidence provides a potential mechanistic basis for propolis activity in breast cancer, which can be optimized for therapeutic intervention in cancer [86,87]. In addition, the results of in vivo and in vitro studies suggest that chrysin in both Chinese propolis and Brazilian green propolis may inhibit tumor cell progression and may be useful as a protential chemotherapeutic or chemopreventive antitumor reagent [88].…”