BackgroundAllicin, a primary ingredient of garlic, has been proposed to possess cardioprotective properties, which are commonly mediated by improved endothelial function.MethodsTo investigate the effect and mechanism of allicin on the apoptosis of human umbilical vein endothelial cells (HUVECs), we used Propidium iodide (PI) staining and Annexin V/ PI staining assays to establish a model of oxidative stress apoptosis induced by H2O2. MTT, RT-PCR and western-blot assays were used to detect the effects and mechanism of allicin on the model.ResultsPI staining, Annexin V/ PI staining assays and morphological assessment suggest that the cell death induced by 0.5 mM H2O2 is primarily apoptotic. Conversely, allicin reverses the effect of H2O2 on cell death, suggesting a role in protecting HUVECs from apoptosis. We demonstrated that H2O2 activates PARP cleavage, reduces pro-Caspase-3 levels and activates Bax expression; however, allicin inhibits each of these apoptotic signaling indicators. Allicin also reduces the levels of malondialdehyde and increases the levels of superoxide dismutase, nitric oxide release and endothelial nitric oxide synthase mRNA, but has no significant effect on inducible nitric oxide synthase mRNA levels.ConclusionThese results demonstrate that allicin has powerful effects in protecting HUVECs from apoptosis and suggest that protection occurs via a mechanism involving the protection from H2O2-mediated oxidative stress.

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Overexpression of microRNA-182 (miR-182) is found in multiple cancers, but the association of miR-182 expression with the sensitivity of triple-negative breast cancer (TNBC) cells to tumor necrosis factor-alpha (TNF-α) remains unknown. In this study, up-regulation of miR-182 was validated in TNBC patients and cell lines. Knockdown of miR-182 was observed to hinder the proliferation of BT-549 cells. More importantly, knockdown of miR-182 significantly promoted the apoptosis induced by TNF-α treatment in BT-549. JC-1 staining and western blot assays revealed that the K63-linked ubiquitin chains on receptor-interacting protein 1 (RIP1) were removed and the outer mitochondrial membrane potential (MMP) and permeability was altered upon combination of TNF-α with anti-miR-182. We then demonstrated that knockdown of miR-182 up-regulated the expression of cylindromatosis (CYLD) deubiquitinase, which promoted the formation of death-inducing signaling complex (DISC) and subsequent caspase-8 activation in TNF-α-treated BT-549 cells. Collectively, the results of the present study improve our understanding of the role of miR-182 in TNBC, knockdown of which facilitates the degradation of ubiquitin chains on RIP1, leading to the caspase-8 activation and apoptosis in TNF-α-treated TNBC cells. This may be valuable for the development of cancer therapy.

Garlic and its water-soluble allyl sulfur-containing compound, S-Allyl-Lcysteine Sulfoxide (ACSO), have shown antioxidant and anti-inflammatory activities, inhibiting the development of atherosclerosis. However, little is known about the mechanism(s) underlying the therapeutic effect of ACSO in inhibiting the formation of atherosclerostic lesion. This study aimed to investigate whether ACSO could modulate tumor necrosis factor-alpha (TNF-a)-induced expression of intercellular cell adhesion molecule-1, monocyte adhesion and TNF-a-mediated signaling in human umbilical vein endothelial cells. While TNF-a promoted the intercellular cell adhesion molecule-1 mRNA transcription in a dose-and time-dependent manner, ACSO treatment significantly reduced the levels of TNF-a-induced intercellular cell adhesion molecule-1 mRNA transcripts (P < 0.01). Furthermore, ACSO dramatically inhibited TNF-a triggered adhesion of THP-1 monocytes to endothelial cells and porcine coronary artery rings. Moreover, ACSO mitigated TNF-a induced depolarization of mitochondrial membrane potential and overproduction of superoxide anion, associated with the inhibition of NOX4, a subunit of nicotinamide adenine dinucleotide phosphate-oxidase, mRNA transcription. In addition, ACSO also inhibited TNF-a-induced phosphorylation of JNK, ERK1/2 and IjB, but not p38. Apparently, ACSO inhibited proinflammatory cytokine-induced adhesion of monocytes to endothelial cells by inhibiting the mitogen-activated protein kinase signaling and related intercellular cell adhesion molecule-1 expression, maintaining mitochondrial membrane potential, and suppressing the overproduction of superoxide anion in endothelial cells. Therefore, our findings may provide new insights into ACSO on controlling TNF-a-mediated inflammation and vascular disease. Anat Rec, 293:421-430, 2010. V V C 2010 Wiley-Liss, Inc.