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Induction of apoptosis in cancer cells can be a promising treatment method in cancer therapy. Naturally derived products had drawn growing attention as agent in cancer therapy. The main target of anticancer drugs may be distinct, but eventually, they lead to identical cell death pathway, which is apoptosis. Here, we indicated that britannin, a sesquiterpene lactone isolated from Asteraceae family, has antiproliferative activity on the MCF-7 and MDA-MB-468 human breast cancer cells. Annexin V/propidium iodide (PI) staining, Hoechst 33258 staining, and caspase-3/9 activity assay confirmed that britannin is able to induce apoptosis in MCF-7 and MDA-MB-468 cells. The Western blot analysis showed that the expression of Bcl-2 was noticeably decreased in response to britannin treatment, while the expression of Bax protein was increased, which were positively correlated with elevated expression of p53. Moreover, britannin also increased reactive oxygen species (ROS) generation which in turn triggered the loss of mitochondrial transmembrane potential (ΔΨm) and the subsequent release of cytochrome c from mitochondria into cytosol. Taken together, these results suggest that britannin inhibits growth of MCF-7 and MDA-MB-468 breast cancer cells through the activation of the mitochondrial apoptotic pathway and may potentially serve as an agent for breast cancer therapy.

Numerous studies have demonstrated the role of A3 adenosine receptor (A3AR) and signaling pathways in the multiple aspects of the tumor. However, there is a little study about the function of A3AR in the biological processes of cancer stem cells (CSCs). CSCs have a critical role in the maintenance and survival of breast cancer. The aim of current study was to investigate the effect of A3AR agonist on breast cancer stem cells (BCSCs). XTT assay showed antiproliferative effect of A3AR agonist (Cl-IB-MECA) on BCSCs. Our results also demonstrated that A3AR agonist reduces mammosphere formation in a dose-dependent manner. Flow cytometry analysis showed that A3AR agonist induces G1 cell cycle arrest and apoptosis in BCSCs. Western blot assay showed that A3AR agonist inhibits the expression of cell cycle and apoptotic regulatory proteins as well as the expression of ERK1/2 and GLI-1 proteins. Finally, these findings propose that A3AR agonist induces cell cycle arrest and apoptosis in BCSCs by inhibition of ERK1/2 and GLI-1 cascade. J. Cell. Biochem. 118: 2909-2920, 2017. © 2017 Wiley Periodicals, Inc.

From our results we conclude that A2BAR induces breast CSC cell cycle arrest and apoptosis through downregulation of the ERK1/2 cascade. As such, A2BAR may be considered as a novel target for the treatment of breast cancer.

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These findings indicated that adenosine induces cell cycle arrest and apoptosis through inhibition of GLI-1 and ERK1/2 pathways in breast CSCs.

Natural products isolated from plants provide a valuable source for expansion of new anticancer drugs. Nardosinen (4,9-dihydroxy-nardosin-6-en) is a natural sesquiterpene extracted from Juniperus foetidissima. Recently, we have reported the cytotoxic effects of nardosinen in various cancer cells. The aim of the current study was to investigate the anticancer features of nardosinen as well as its possible molecular mechanisms of the nardosinen cytotoxic effect on breast tumor cells. MTT assay showed that nardosinen notably inhibited cell proliferation in a dose-dependent manner in MCF-7 breast cancer cells. The growth inhibitory effect of nardosinen was associated with the induction of cell apoptosis, activation of caspase-6, increase of reactive oxygen species (ROS), and loss of mitochondrial membrane potentials (ΔΨm). Western blot assay following treatment with nardosinen showed that the expression levels of the Bax were significantly up-regulated and the expression levels of the Bcl-2 were significantly down-regulated. Our results finally exhibited that nardosinen induces apoptosis in breast cancer cells via the mitochondrial and caspase pathways.