Efficient degradation of tetracycline residues in pharmaceutical wastewater by Ni/Fe bimetallic atomic cluster composite catalysts with enhanced electron transfer pathway.

Metal cluster catalysts have large atomic load, interaction between atomic sites, and wide application of catalysis. In this study, a Ni/Fe bimetallic cluster material was prepared by a simple hydrothermal method and used as an efficient catalyst to activate the degradation system of peroxymonosulfate (PMS), which showed nearly 100% tetracycline (TC) degradation performance over a wide pH range (pH = 3-11). The results of electron paramagnetic resonance test, quenching experiment and density functional theory (DFT) calculation show that the non-free radical pathway electron transfer efficiency of the catalytic system is effectively improved, and a large number of PMS are captured and activated by high density Ni atomic clusters in Ni/Fe bimetallic clusters. The degradation intermediates identified by LC/MS showed that TC was efficiently degraded into small molecules. In addition, the Ni/Fe bimetallic cluster/PMS system has excellent efficiency for degrading various organic pollutants and practical pharmaceutical wastewater. This work opens up a new way for metal atom cluster catalysts to efficiently catalyze the degradation of organic pollutants in PMS systems.

Narasin inhibits tumor metastasis and growth of ERα­positive breast cancer cells by inactivation of the TGF­ß/SMAD3 and IL­6/STAT3 signaling pathways.

Treatment of human estrogen receptor (ER)­positive breast cancer (ER+ BC) using conventional chemotherapy remains a challenge and is often ineffective as a result of tumor metastasis. The present study aimed to investigate the ability of narasin, an ionophore antibiotic, to potentially inhibit tumor metastasis and growth in human ER+ BC. Narasin was found to have significant inhibitory abilities on cell proliferation, migration and invasion in ER+ BC cell lines MCF­7 and T47D compared with the triple­negative BC cell MDA­MB­231. For the in vivo studies, narasin effectively decreased the number of tumor metastasis nodules, tumor volume and weight without apparent toxicity in human MCF­7 nude mouse left ventricle injection tumor metastasis and xenograft models. Mechanistically, it demonstrated that exposure to TGF­ß or IL­6 induced the expression of epithelial­mesenchymal transition (EMT) markers in ER+ BC cell lines. On the contrary, narasin dose­dependently reversed EMT by increasing the expression of E­cadherin and decreasing the expression of N­cadherin, vimentin, ß­catenin and zinc finger E­box­binding homeobox 1 at the protein and gene expression levels. Gene microarray, molecular docking and western blotting were performed to demonstrate that those protein and gene expression levels are regulated by the inactivation of the TGF­ß/phosphorylated (p)­SMAD3 and IL­6/p­STAT3 signaling pathways. Taken together, these findings indicated that narasin may be a promising candidate that can be further optimized for the treatment of human ER+ BC.

Pracinostat (SB939), a histone deacetylase inhibitor, suppresses breast cancer metastasis and growth by inactivating the IL-6/STAT3 signalling pathways.

AIMS: Histone deacetylases inhibitors have shown favorable antitumor activity in clinical investigations. In the present study, we assessed the effects of a novel hydroxamic acid-based HDAC inhibitor, SB939, on breast cancer metastasis and tumor growth and characterized the underlying molecular mechanisms. MAIN METHODS: MTS, Wound-healing, and Transwell chamber invasion assays were used to detect the inhibition effects of SB939 on proliferation, migration, and invasion of breast cancer cells. Western blot, cellular immunofluorescence, and EMSA were used to explore the molecular mechanism of SB939 in suppressing breast cancer metastasis. MDA-MB-231 subcutaneous tumor-bearing model of nude mice and the spontaneous metastasis model of breast cancer were both applied to verify in vivo anti-tumor growth and anti-metastatic effects. KEY FINDINGS: Our results demonstrated that SB939 at 0.5-1 µmol/L markedly impaired the chemotactic motility of breast cancer cells. SB939 reversed epithelial-mesenchymal transition (EMT) process, as evidenced by upregulation E-cadherin expression and downregulation expressions of N-cadherin and vimentin through increasing the levels of ac-histone H3 and H4 and drecreasing the expressiongs of HDAC 5 and 4. This cascade inhibition mediated by SB939 was well interpreted by inactivating phosphorylation of STAT3, blocking its DNA-binding activity, and decreasing the expressions of STAT3-dependent target genes, including MMP2 and MMP9. Furhtermore, we found that SB939 significantly inhibited breast cancer metastasis and tumor growth in vivo and showed superior anti-tumor properties compared with SAHA in two breast cancer animal models. SIGNIFICANCE: Our findings indicate that SB939 may be an effective therapeutic option for treating advanced breast cancer.

Limonin inhibits angiogenesis and metastasis of human breast cancer cells by suppressing the VEGFR2/IGFR1-mediated STAT3 signaling pathway.

BACKGROUND: Limonin is one of the major active ingredients of citrus. In the present study, the anti-angiogenic and anti-metastatic effects of limonin were investigated. METHODS: The Molecular docking assay was carried out to assess the binding ability of limonin with VEGFR2 receptor. MTS assay was used to detect the effect of limonin on the proliferation of breast cancer cells (MDA-MB-231, MCF-7). The Wound-healing and Transwell chamber invasion assays were used to detect the inhibition effect of limonin on migration and invasion of HUVECs cells or breast cancer cells. The capillary-like tube formation assay and Matrixgel plug experiment were used to further measure the in vivo anti-angiogenic activity of limonin. Western blot, RNA isolation, microarray data analysis and RT-PCR were used to explore the molecular mechanism of limonin in suppressing breast cancer angiogenesis and metastasis. Left ventricular tumor metastasis model and caudal vein tumor metastasis model of breast cancer were both applied to verify in vivo anti-metastatic effects. RESULTS: Limonin dose-dependently inhibited the vascular endothelial growth factor (VEGF)-mediated tyrosine phosphorylation of vascular endothelial growth factor receptor 2 (VEGFR2) by blocking VEGF binding to VEGFR2 and suppressing constitutive STAT3 activation in human umbilical vein endothelial cells. Limonin effectively inhibited VEGF-induced endothelial cell proliferation, migration and tubular-structure formation in vitro and markedly reduced VEGF-triggered neovascularization in mouse matrigel plugs in vivo. Moreover, limonin treatment led to a remarkable suppression of tumor metastasis by decreasing the phosphorylation of insulin growth factor receptor 1-mediated STAT3 and the expression levels of its downstream members MMP-9 and VEGF in breast cancer cells. The data further showed that limonin increased the levels of the negative STAT3 regulator SHP-1 in breast cancer cells. CONCLUSIONS: Limonin is a promising anti-angiogenic and anti-metastatic candidate compound that can be further optimized as a therapeutic agent for breast cancer.