Effect of coumarin and diallyl polysulfides on HCT116 colon cancer cells

Polysulfanes from garlic are regarded as potential chemopreventive compounds as they have proven to be effective inhibitors of cancer cells. Yet, certain aspects of the triggered inhibitory effects remain unclear. The aim of this study was, hence, to determine the anti-carcinogenic properties of novel coumarin and diallyl polysulfides against HCT116 colorectal cancer cells. These polysulfides inhibited the viability and proliferation of cultured HCT116 cells in a time- and dose-dependent manner. The mechanism of cell inhibition included cell cycle arrest and induction of apoptosis. While polysulfanes are known to cause oxidative stress, little is known about the underlying signalling cascades leading to antioxidant defence or apoptosis. It was, thus, hypothesised in this study that polysulfanes may induce ROS generation and/or regulate cellular thiol, which in turn may regulate signalling pathways leading to cell survival or apoptosis. The effect of polysulfanes on cellular thiol, ROS and ER stress signalling pathways was hence analysed. An immediate rise in the level of O2•-, H2O2 and an overall thiol depletion was found. There was also an increase in PERK and eIF2 phosphorylation along with Nrf2, HO-1, and NQO1 protein levels in a time- and concentration-dependent manner. Pre-treatment of cells with antioxidants drastically reduced the high expression levels of these proteins. A direct role of Nrf2 was shown by its interaction with the stress response element of the HO-1 promoter. Interestingly, however, not only did DATTS fail to induce cell cycle arrest in the G2/M phase of the cell cycle in normal epithelial ARPE-19 cells, but also apoptosis and ER stress. This study, shows for the first time, a parallel but not equal activation of signaling pathways by DATTS in particular, with a competitive ultimate cellular outcome. Results also suggest that the inhibitory and apoptotic effects are more prominent in HCT116 cancer cells than in ARPE-19 noncancer cells.Polysulfane sind Inhaltsstoffe des Knoblauchs, die als potentielle pharmakologisch wirksame Verbindungen betrachtet werden, da sie sich als Hemmstoffe des Krebszellwachstums herauskristallisiert haben. Zahlreiche Aspekte dieser Hemmung sind noch unklar. Das Ziel dieser Studie war es daher, die antikarzinogenen Eigenschaften von neuartigen Cumarin- und Diallylpolysulfanen in der Darmkrebszelllinie HCT116 zu bestimmen. Diese Polysulfane hemmen Wachstum und Vitalität der kultivierten HCT116 Zellen in einer zeit- und dosisabhängigen Weise. Der Mechanismus der Hemmung umfasst einen Zellzyklusarrest und die Induktion von Apoptose. Während Polysulfane dafür bekannt sind, oxidativen Stress zu verursachen, ist nur wenig über die Signalwege bekannt, die zur Verteidigung mittels Antioxidantien oder Apoptose führen. Dieser Arbeit liegt die Hypothese zugrunde, dass Polysulfane zu ROS-Entstehung führen und/oder zelluläres Thiol regulieren könnten, was wiederum Signalwege regulieren könnte, die über Apoptose oder Überleben entscheiden. Tatsächlich konnte ein unmittelbarer Anstieg von O2•--Radikalen und H2O2, sowie eine Abnahme der Thiolkonzentration gezeigt werden. Es war auch ein zeit- und dosisabhängiger Anstieg der Expression von ER-Stress Markerproteinen zu beobachten. Die Vorbehandlung der Zellen mit Antioxidantien reduzierte die Expression dieser Proteine drastisch. Eine direkte Rolle von Nrf2 auf HO-1 wurde durch die Interaktion mit dem StRE-Promotorelement des HO-1 Gens gezeigt. Interessanterweise konnte Diallyltetrasulfan (DATTS) in der normalen Epithelzelllinie ARPE-19 weder einen G2/M Zellzyklusarrest, noch ER-Stress oder Apoptose induzieren. Diese Studie zeigte erstmals eine parallele, aber nicht identische Aktivierung von Signalwegen durch DATTS mit kompetitivem Ausgang für die Zelle. Die Ergebnisse legen außerdem nahe, dass die hemmenden und apoptotischen Effekte von DATTS in HCT116 Krebszellen deutlich stärker sind als in ARPE-19 Nicht-Krebszellen

The Nrf2-Antioxidant Response Element Signaling Pathway Controls Fibrosis and Autoimmunity in Scleroderma

Systemic sclerosis (SSc) is an autoimmune disease with fibrosis of the skin and internal organs and vascular alterations. Dysregulations in the oxidant/antioxidant balance are known to be a major factor in the pathogenesis of the disease. Indeed, reactive oxygen species (ROS) trigger neoepitopes leading to a breach of immune tolerance and autoimmune responses, activate fibroblasts to proliferate and to produce excess of type I collagen. ROS also alter endothelial cells leading to vascular dysfunction. Glutathione (GSH) is the most potent antioxidant system in eukaryotic cells. Numerous studies have reported a defect in GSH in SSc animal models and humans, but the origin of this defect remains unknown. The transcription factor NRF2 is a key player in the antioxidant defense, as it can induce the transcription of antioxidant and cytoprotective genes, including GSH, through its interaction with the antioxidant response elements. In this work, we investigated whether NRF2 could be implicated in the pathogenesis of SSc, and if this pathway could represent a new therapeutic target in this orphan disease with no curative medicine. Skin biopsies from 11 patients and 10 controls were harvested, and skin fibroblasts were extracted. Experimental SSc was induced both in BALB/c and in nrf2−/− mice by daily intradermal injections of hypochloric acid. In addition, diseased BALB/c mice were treated with an nrf2 agonist, dimethyl fumarate, or placebo. A drop in nrf2 and target genes mRNA levels was observed in skin fibroblasts of SSc patients compared to controls. Moreover, the nrf2 pathway is also downregulated in skins and lungs of SSc mice. In addition, we observed that nrf2−/− mice have a more severe form of SSc with increased fibrosis and inflammation compared to wild-type SSc mice. Diseased mice treated with the nrf2 agonist dimethyl fumarate (DMF) exhibited reduced fibrosis and immune activation compared to untreated mice. The ex vivo treatment of skin fibroblasts from SSc mice with DMF restores GSH intracellular content, decreases ROS production and cell proliferation. These results suggest that the nrf2 pathway is highly dysregulated in human and SSc mice with deleterious consequences on fibrosis and inflammation and that Nrf2 modulation represents a therapeutic target in SSc

Wirkung von Cumarin und Diallyl Polysulfide auf Darmkrebszellen HCT116

Polysulfanes from garlic are regarded as potential chemopreventive compounds as they have proven to be effective inhibitors of cancer cells. Yet, certain aspects of the triggered inhibitory effects remain unclear. The aim of this study was, hence, to determine the anti-carcinogenic properties of novel coumarin and diallyl polysulfides against HCT116 colorectal cancer cells. These polysulfides inhibited the viability and proliferation of cultured HCT116 cells in a time- and dose-dependent manner. The mechanism of cell inhibition included cell cycle arrest and induction of apoptosis. While polysulfanes are known to cause oxidative stress, little is known about the underlying signalling cascades leading to antioxidant defence or apoptosis. It was, thus, hypothesised in this study that polysulfanes may induce ROS generation and/or regulate cellular thiol, which in turn may regulate signalling pathways leading to cell survival or apoptosis. The effect of polysulfanes on cellular thiol, ROS and ER stress signalling pathways was hence analysed. An immediate rise in the level of O2•-, H2O2 and an overall thiol depletion was found. There was also an increase in PERK and eIF2 phosphorylation along with Nrf2, HO-1, and NQO1 protein levels in a time- and concentration-dependent manner. Pre-treatment of cells with antioxidants drastically reduced the high expression levels of these proteins. A direct role of Nrf2 was shown by its interaction with the stress response element of the HO-1 promoter. Interestingly, however, not only did DATTS fail to induce cell cycle arrest in the G2/M phase of the cell cycle in normal epithelial ARPE-19 cells, but also apoptosis and ER stress. This study, shows for the first time, a parallel but not equal activation of signaling pathways by DATTS in particular, with a competitive ultimate cellular outcome. Results also suggest that the inhibitory and apoptotic effects are more prominent in HCT116 cancer cells than in ARPE-19 noncancer cells.Polysulfane sind Inhaltsstoffe des Knoblauchs, die als potentielle pharmakologisch wirksame Verbindungen betrachtet werden, da sie sich als Hemmstoffe des Krebszellwachstums herauskristallisiert haben. Zahlreiche Aspekte dieser Hemmung sind noch unklar. Das Ziel dieser Studie war es daher, die antikarzinogenen Eigenschaften von neuartigen Cumarin- und Diallylpolysulfanen in der Darmkrebszelllinie HCT116 zu bestimmen. Diese Polysulfane hemmen Wachstum und Vitalität der kultivierten HCT116 Zellen in einer zeit- und dosisabhängigen Weise. Der Mechanismus der Hemmung umfasst einen Zellzyklusarrest und die Induktion von Apoptose. Während Polysulfane dafür bekannt sind, oxidativen Stress zu verursachen, ist nur wenig über die Signalwege bekannt, die zur Verteidigung mittels Antioxidantien oder Apoptose führen. Dieser Arbeit liegt die Hypothese zugrunde, dass Polysulfane zu ROS-Entstehung führen und/oder zelluläres Thiol regulieren könnten, was wiederum Signalwege regulieren könnte, die über Apoptose oder Überleben entscheiden. Tatsächlich konnte ein unmittelbarer Anstieg von O2•--Radikalen und H2O2, sowie eine Abnahme der Thiolkonzentration gezeigt werden. Es war auch ein zeit- und dosisabhängiger Anstieg der Expression von ER-Stress Markerproteinen zu beobachten. Die Vorbehandlung der Zellen mit Antioxidantien reduzierte die Expression dieser Proteine drastisch. Eine direkte Rolle von Nrf2 auf HO-1 wurde durch die Interaktion mit dem StRE-Promotorelement des HO-1 Gens gezeigt. Interessanterweise konnte Diallyltetrasulfan (DATTS) in der normalen Epithelzelllinie ARPE-19 weder einen G2/M Zellzyklusarrest, noch ER-Stress oder Apoptose induzieren. Diese Studie zeigte erstmals eine parallele, aber nicht identische Aktivierung von Signalwegen durch DATTS mit kompetitivem Ausgang für die Zelle. Die Ergebnisse legen außerdem nahe, dass die hemmenden und apoptotischen Effekte von DATTS in HCT116 Krebszellen deutlich stärker sind als in ARPE-19 Nicht-Krebszellen

Coumarin polysulfides inhibit cell growth and induce apoptosis in HCT116 colon cancer cells

Coumarins and coumarin derivatives as well as diallyl polysulfides are well known as anticancer drugs. In order to find new drugs with anticancer activities, we combined coumarins with polysulfides in the form of di-coumarin polysulfides. These novel compounds were tested in the HCT116 colorectal cancer cell line. It turned out that they reduced cell viability of cancer cells in a time and concentration dependent manner. Cells tested with these coumarin polysulfides accumulate in the G(2)/M phase of the cell cycle and finally they go into apoptosis. A decrease in bcl-2 level, and increase in the level of bax, cytochrome c release into the cytosol, cleavage of caspase 3/7and PARP suggested that coumarin polysulfides induced the intrinsic pathway of apoptosis. Comparison of these new coumarin compounds with the well known diallyl polysulfides revealed that the coumarin disulfides were more active than the corresponding diallyl disulfides. The activities of the coumarin tetrasulfides and the corresponding diallyl tetrasulfides are similar. The novel coumarin compounds regulated the phosphatase activity of the cell cycle regulating cdc25 family members, indicating that these phosphatases are implicated in the induction of cell cycle arrest and possibly in apoptosis induction as well. In addition, coumarin polysulfides also down-regulated the level of cdc25C, which also contributed to the arrest in the G(2)-phase of the cell cycle. (C) 2011 Elsevier Ltd. All rights reserved

Preventive action of benztropine on platinum-induced peripheral neuropathies and tumor growth

Abstract The endogenous cholinergic system plays a key role in neuronal cells, by suppressing neurite outgrowth and myelination and, in some cancer cells, favoring tumor growth. Platinum compounds are widely used as part of first line conventional cancer chemotherapy; their efficacy is however limited by peripheral neuropathy as a major side-effect. In a multiple sclerosis mouse model, benztropine, that also acts as an anti-histamine and a dopamine re-uptake inhibitor, induced the differentiation of oligodendrocytes through M1 and M3 muscarinic receptors and enhanced re-myelination. We have evaluated whether benztropine can increase anti-tumoral efficacy of oxaliplatin, while preventing its neurotoxicity. We showed that benztropine improves acute and chronic clinical symptoms of oxaliplatin-induced peripheral neuropathies in mice. Sensory alterations detected by electrophysiology in oxaliplatin-treated mice were consistent with a decreased nerve conduction velocity and membrane hyperexcitability due to alterations in the density and/or functioning of both sodium and potassium channels, confirmed by action potential analysis from ex-vivo cultures of mouse dorsal root ganglion sensory neurons using whole-cell patch-clamp. These alterations were all prevented by benztropine. In oxaliplatin-treated mice, MBP expression, confocal and electronic microscopy of the sciatic nerves revealed a demyelination and confirmed the alteration of the myelinated axons morphology when compared to animals injected with oxaliplatin plus benztropine. Benztropine also prevented the decrease in neuronal density in the paws of mice injected with oxaliplatin. The neuroprotection conferred by benztropine against chemotherapeutic drugs was associated with a lower expression of inflammatory cytokines and extended to diabetic-induced peripheral neuropathy in mice. Mice receiving benztropine alone presented a lower tumor growth when compared to untreated animals and synergized the anti-tumoral effect of oxaliplatin, a phenomenon explained at least in part by benztropine-induced ROS imbalance in tumor cells. This report shows that blocking muscarinic receptors with benztropine prevents peripheral neuropathies and increases the therapeutic index of oxaliplatin. These results can be rapidly transposable to patients as benztropine is currently indicated in Parkinson’s disease in the United States

Corrigendum: The Nrf2-Antioxidant Response Element Signaling Pathway Controls Fibrosis and Autoimmunity in Scleroderma

[This corrects the article DOI: 10.3389/fimmu.2018.01896.]