Fas signaling was reported to participate in cell apoptosis. However, this pathway has also been shown to promote tumor cell motility, leading to the hypothesis that Fas signaling may induce epithelial-mesenchymal transition (EMT) to promote metastasis. The effects of Fas-ligand (FasL) treatment and inhibition of Fas signaling on colorectal and gastric cancer cells were tested using motility assay, immunofluorescence, RT-PCR and immunoblot analyses. Fas signaling downregulated epithelial markers, upregulated mesenchymal markers and promoted motility in gastrointestinal (GI) cancer cells. FasL treatment also increased the expression of EMT transcriptional factors in the nucleus and induced a spindle shape cell morphology in these cells. Knockdown of Snail or Twist expression significantly decreased FasL-induced motility. The ERK1/2 pathway was activated by Fas signaling and is required for FasL-induced EMT and motility. Moreover, oxaliplatin, a chemotherapeutic agent, induced EMT partly through Fas signaling. Evaluation of human GI clinical specimens showed that FasL expression increased whereas E-cadherin expression decreased during GI cancer progression. Both markers were significantly inversely correlated. Tissue samples with a non-EMT phenotype were mainly distributed in patients with early cancer stages, whereas samples with an EMT phenotype were mostly distributed in patients with advanced cancer stages. A non-EMT phenotype significantly correlated with better prognosis. Altogether, these data indicate that Fas signaling may induce EMT to promote tumor motility and metastasis in GI cancer in vivo and in vitro.
ObjectiveStatins are commonly prescribed cholesterol-lowering drugs. Preclinical studies suggest that statins may possess cancer preventive properties. The primary objective of this meta-analysis was to determine the association between statin use and risk of liver cancer.DesignMeta-analysis.SettingInternational.ParticipantsA comprehensive literature search of PubMed, BIOSIS Previews, Web of Science, EMBASE, EBSCO and Cochrane Library was conducted through March 2014. The effect estimate was reported as pooled relative risk (RR) with 95% CIs, using the random-effects model.ResultsA total of 12 studies (1 individual patient data analysis of 22 randomised controlled trials, 5 cohorts and 6 case–controls) were qualified for this meta-analysis, involving 5 640 313 participants including 35 756 liver cancer cases. Our results indicated a significant risk reduction of liver cancer among all statin users (RR=0.58, 95% CIs 0.51 to 0.67). The difference of the study designs can partly explain the significant heterogeneity found in the overall analysis (I2=65%, p=0.0006). No evidence of publication bias was observed in this meta-analysis. Similar risk reductions were found in the subgroups analysis of Western and Asian countries, lipophilic and hydrophilia statins. There was a trend towards more risk reductions in subgroups with higher baseline risk, inadequate adjustment and higher cumulative dosage of statin use.ConclusionsThis meta-analysis suggests that statin is associated with a significant risk reduction of liver cancer when taken daily for cardiovascular event prevention. However, this preventive effect might be overestimated due to the exposure period, the indication and contraindication of statins and other confounders. Statins might be considered as an adjuvant in the treatment of liver cancer.
Recent evidence has shown that an increase in CD4+CD25+FoxP3+ regulatory T (Treg) cells may contribute to stroke-induced immunosuppression. However, the molecular mechanisms that underlie this increase in Treg cells remain unclear. Here, we used a transient middle cerebral artery occlusion model in mice and specific pathway inhibitors to demonstrate that stroke activates the sympathetic nervous system, which was abolished by 6-OHDA. The consequent activation of β2-adrenergic receptor (AR) signaling increased prostaglandin E2 (PGE2) level in bone marrow. β2-AR antagonist prevented the upregulation of PGE2. PGE2, which acts on prostaglandin E receptor subtype 4 (EP4), upregulated the expression of receptor activator for NF-κB ligand (RANKL) in CD4+ T cells and mediated the increase in Treg cells in bone marrow Treatment of MCAO mice with RANKL antagonist OPG inhibited the increase in percent of bone marrow Treg cells. PGE2 also elevated the expression of indoleamine 2,3 dioxygenase in CD11C+ dendritic cells and promoted the development of functional Treg cells. The effect was neutralized by treatment with indomethacin. Concurrently, stroke reduced production of stromal cell-derived factor-1 (SDF-1) via β3-AR signals in bone marrow but increased the expression of C-X-C chemokine receptor (CXCR) 4 in Treg and other bone marrow cells. Treatment of MCAO mice with β3-AR antagonist SR-59230A reduced the percent of Treg cells in peripheral blood after stroke. The disruption of the CXCR4–SDF-1 axis may facilitate mobilization of Treg cells and other CXCR4+ cells into peripheral blood. This mechanism could account for the increase in Treg cells, hematopoietic stem cells, and progenitor cells in peripheral blood after stroke. We conclude that cerebral ischemia can increase bone marrow CD4+CD25+FoxP3+ regulatory T cells via signals from the sympathetic nervous system.
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