Polyphenols from Artemisia annua L Inhibit Adhesion and EMT of Highly Metastatic Breast Cancer Cells MDA‐MB‐231

Recent evidence suggests that polyphenolic compounds from plants have anti‐invasion and anti‐metastasis capabilities. The Korean annual weed, Artemisia annua L., has been used as a folk medicine for treatment of various diseases. Here, we isolated and characterized polyphenols from Korean A. annua L (pKAL). We investigated anti‐metastatic effects of pKAL on the highly metastatic MDA‐MB‐231 breast cancer cells especially focusing on cancer cell adhesion to the endothelial cell and epithelial‐mesenchymal transition (EMT). Firstly, pKAL inhibited cell viability of MDA‐MB‐231 cells in a dose‐dependent manner, but not that of human umbilical vein endothelial cells (ECs). Polyphenols from Korean A. annua L inhibited the adhesion of MDA‐MB‐231 cells to ECs through reducing vascular cell adhesion molecule‐1 expression of MDA‐MB‐231 and ECs, but not intracellular adhesion molecule‐1 at the concentrations where pKAL did not influence the cell viability of either MDA‐MB‐231 cells nor EC. Further, pKAL inhibited tumor necrosis factor‐activated MDA‐MB‐231 breast cancer cell invasion through inhibition of matrix metalloproteinase‐2 and matrix metalloproteinase‐9 and EMT. Moreover, pKAL inhibited phosphorylation of Akt, but not that of protein kinase C. These results suggest that pKAL may serve as a therapeutic agent against cancer metastasis at least in part by inhibiting the cancer cell adhesion to ECs through suppression of vascular cell adhesion molecule‐1 and invasion through suppression of EMT. Copyright © 2016 John Wiley & Sons, Ltd.     

Theacrine attenuates epithelial mesenchymal transition in human breast cancer MDA‐MB‐231 cells

Theacrine, a purine alkaloid structurally similar to caffeine, has recently become of interest as a potential therapeutic compound. Here, we investigated the antimetastatic potential of theacrine on human breast cancer MDA‐MB‐231 cells. We observed that theacrine can reverse epithelial‐to‐mesenchymal transition (EMT), which resulted in a decrease in the levels of mesenchymal markers (Fibronectin, Vimentin, N‐cadherin, Twist, and Snail) and an increase in the levels of epithelial markers (Occludin and E‐cadherin) in the cells. Additionally, theacrine attenuates TGF‐β‐induced EMT, cell adhesion, migration, and invasion in MDA‐MB‐231 cells. Overall, our results suggest that theacrine may inhibit the breast cancer cell metastasis by reversing the EMT process.     

High Throughput Screening of Natural Products for Anti‐mitotic Effects in MDA‐MB‐231 Human Breast Carcinoma Cells

Some of the most effective anti‐mitotic microtubule‐binding agents, such as paclitaxel (Taxus brevifolia) were originally discovered through robust National Cancer Institute botanical screenings. In this study, a high‐through put microarray format was utilized to screen 897 aqueous extracts of commonly used natural products (0.00015–0.5 mg/mL) relative to paclitaxel for anti‐mitotic effects (independent of toxicity) on proliferation of MDA‐MB‐231 cells. The data obtained showed that less than 1.34 % of the extracts tested showed inhibitory growth (IG₅₀) properties <0.0183 mg/mL. The most potent anti‐mitotics (independent of toxicity) were Mandrake root (Podophyllum peltatum), Truja twigs (Thuja occidentalis), Colorado desert mistletoe (Phoradendron flavescens), Tou Gu Cao Speranskia herb (Speranskia tuberculata), Bentonite clay, Bunge root (Pulsatilla chinensis), Brucea fruit (Brucea javanica), Madder root (Rubia tinctorum), Gallnut of Chinese Sumac (Melaphis chinensis), Elecampane root (Inula Helenium), Yuan Zhi root (Polygala tenuifolia), Pagoda Tree fruit (Melia Toosendan), Stone root (Collinsonia Canadensis), and others such as American Witchhazel, Arjun, and Bladderwrack. The strongest tumoricidal herbs identified from amongst the subset evaluated for anti‐mitotic properties were wild yam (Dioscorea villosa), beth root (Trillium Pendulum), and alkanet root (Lithospermum canescens). Additional data was obtained on a lesser‐recognized herb: (S. tuberculata), which showed growth inhibition on BT‐474 (human ductal breast carcinoma) and Ishikawa (human endometrial adenocarcinoma) cells with ability to block replicative DNA synthesis, leading to G2 arrest in MDA‐MB‐231 cells. In conclusion, these findings present relative potency of anti‐mitotic natural plants that are effective against human breast carcinoma MDA‐MB‐231 cell division. Copyright © 2013 John Wiley & Sons, Ltd.     

Norstictic Acid Inhibits Breast Cancer Cell Proliferation,Migration, Invasion,and In Vivo Invasive Growth Through Targeting C‐Met

Breast cancer is a major health problem affecting the female population worldwide. The triple‐negative breast cancers (TNBCs) are characterized by malignant phenotypes, worse patient outcomes, poorest prognosis, and highest mortality rates. The proto‐oncogenic receptor tyrosine kinase c‐Met is usually dysregulated in TNBCs, contributing to their oncogenesis, tumor progression, and aggressive cellular invasiveness that is strongly linked to tumor metastasis. Therefore, c‐Met is proposed as a promising candidate target for the control of TNBCs. Lichens‐derived metabolites are characterized by their structural diversity, complexity, and novelty. The chemical space of lichen‐derived metabolites has been extensively investigated, albeit their biological space is still not fully explored. The anticancer‐guided fractionation of Usnea strigosa (Ach.) lichen extract led to the identification of the depsidone‐derived norstictic acid as a novel bioactive hit against breast cancer cell lines. Norstictic acid significantly suppressed the TNBC MDA‐MB‐231 cell proliferation, migration, and invasion, with minimal toxicity to non‐tumorigenic MCF‐10A mammary epithelial cells. Molecular modeling, Z'‐LYTE biochemical kinase assay and Western blot analysis identified c‐Met as a potential macromolecular target. Norstictic acid treatment significantly suppressed MDA‐MB‐231/GFP tumor growth of a breast cancer xenograft model in athymic nude mice. Lichen‐derived natural products are promising resources to discover novel c‐Met inhibitors useful to control TNBCs. Copyright © 2016 John Wiley & Sons, Ltd.     

Zanthoxylum usambarense (Engl.) Kokwaro (Rutaceae) Extracts Inhibit the Growth of the Breast Cancer Cell Lines MDA‐MB‐231 and MCF‐7, But Not the Brain Tumour Cell Line U251 In Vitro

Zanthoxylum usambarense (Engl.) Kokwaro has traditionally been used for the treatment of malaria, upper respiratory tract infections, cough, rheumatism, tooth decay and sore gums in Kenya and other African countries. Dried ground parts of Z. usambarense were extracted by maceration using methanol (MeOH) at room temperature, extract was dried and reconstituted in 70% aq. MeOH and partitioned against n‐hexane and chloroform (CHCl₃) to obtain MeOH, n‐hexane and CHCl₃ extracts. All extracts were assessed for cytotoxicity against two breast cancer cell lines, MDA‐MB‐231 and MCF‐7, and the brain tumour cell line U251 by the MTT assay. The free‐radical scavenging activity of the extracts was also determined by the 2,2‐diphenyl‐1‐picryhydrazyl (DPPH) assay. In the DPPH assay, the MeOH extract was found to be the most active free‐radical scavenger with a RC₅₀ value of 41.1 × 10^?3 mg/mL. It also displayed significant cytotoxicity against the MCF‐7 cell line (IC₅₀ 42.9 µg/mL) and appeared to have induced cell death through apoptosis. None of the test extracts showed any activity against the U251 cell line at test concentrations. The present findings demonstrated that Z. usambarense could be a potential source for new cytotoxic compounds for possible anticancer drug development. Copyright © 2012 John Wiley & Sons, Ltd.     

Zerumbone Suppresses IL‐1β‐induced Cell Migration and Invasion by Inhibiting IL‐8 and MMP‐3 Expression in Human Triple‐negative Breast Cancer Cells

Inflammation is a key regulatory process in cancer development. Prolonged exposure of breast tumor cells to inflammatory cytokines leads to epithelial‐mesenchymal transition, which is the principal mechanism involved in metastasis and tumor invasion. Interleukin (IL)‐1β is a major inflammatory cytokine in a variety of tumors. To date, the regulatory mechanism of IL‐1β‐induced cell migration and invasion has not been fully elucidated. Here, we investigated the effect of zerumbone (ZER) on IL‐1β‐induced cell migration and invasion in breast cancer cells. The levels of IL‐8 and matrix metalloproteinase (MMP)‐3 mRNA were analyzed by real‐time polymerase chain reaction. The levels of secreted IL‐8 and MMP‐3 protein were analyzed by enzyme‐linked immunosorbent assay and western blot analysis, respectively. Cell invasion and migration was detected by Boyden chamber assay. The levels of IL‐8 and MMP‐3 expression were significantly increased by IL‐1β treatment in Hs578T and MDA‐MB231 cells. On the other hand, IL‐1β‐induced IL‐8 and MMP‐3 expression was decreased by ZER. Finally, IL‐1β‐induced cell migration and invasion were decreased by ZER in Hs578T and MDA‐MB231 cells. ZER suppresses IL‐1β‐induced cell migration and invasion by inhibiting IL‐8 expression and MMP‐3 expression in TNBC cells. ZER could be a promising therapeutic drug for treatment of triple‐negative breast cancer patients. Copyright © 2014 John Wiley & Sons, Ltd.