Isoliquiritigenin inhibits the growth of multiple myeloma via blocking IL-6 signaling

Previous studies have suggested that isoliquiritigenin (ISL) has anti-carcinogenic activity in several kinds of solid tumors, however, little is known about the effects of ISL on hematologic malignancies. In this study, we investigated the effects of ISL on multiple myeloma (MM) cells both in vitro and in vivo. The results showed that ISL could inhibit the growth of MM cells and induce their apoptosis in time- and dose-dependent manners. ISL exhibited significant anti-tumor activity in MM xenograft models and synergistically enhanced the anti-myeloma activity of adriamycin. Further analysis demonstrated that ISL not only downregulated IL-6 expression but also significantly decreased levels of phosphorylated ERK and STAT3 and could inhibit phosphorylation levels of ERK and STAT3 induced by recombinant human IL-6, which are critical signaling proteins in IL-6 signaling regulation networks. Taken together, our findings suggested that ISL could inhibit the growth of MM via blocking IL-6 signaling and might serve as a promising therapeutic agent for treatment of MM.     

Blockade of IL-6 signaling exacerbates liver injury and suppresses antiapoptotic gene expression in methionine choline-deficient diet-fed db/db mice

Our previous study revealed that blockade of interleukin-6 (IL-6)-STAT3 signaling ameliorated liver injury, although hepatic STAT3(-/-) or GP130(-/-) mice have been reported to develop severe liver injury, in a murine methionine choline deficient (MCD) diet-induced model of non-alcoholic steatohepatitis (NASH). In this study, to determine whether profound blockade of IL-6-STAT3 signaling may still ameliorate liver injury, we studied db/db mice, which have impaired leptin-mediated STAT3 activation, using the MCD diet-induced NASH model. Male lean and db/db mice (6 weeks old) were fed either control chow or an MCD diet for 8 or 12 weeks. Half of the mice were treated with 15 mg/kg rat anti-mouse IL-6 receptor neutralizing antibody (MR16-1) intraperitoneally twice weekly, the remainder were injected with 15 mg/kg rat IgG as a control. Hepatic steatosis, injury, fibrosis, markers of lipid peroxidation/oxidant stress and antiapoptotic gene expression were evaluated. Plasma IL-6 levels were elevated in all groups of db/db mice. Although hepatic IL-6/ GP130 signaling was activated in chow-fed db/db mice, this was suppressed in MCD diet-fed db/db mice, accompanied by downregulation of hepatic IL-6 receptor and GP130 mRNA expression. MR16-1 treatment of MCD diet-fed db/db mice further repressed STAT3 activities and expression of STAT3-related antiapoptotic genes, such as Bcl-2 and Ref-1, but increased plasma-free fatty acid and hepatic markers of lipid peroxidation/oxidant stress, leading to increased liver injury, hepatocyte apoptosis and liver fibrosis. Although 'moderate' blockade of enhanced IL-6-STAT3 signaling may be beneficial in NASH, as we reported previously, these findings demonstrate that a profound defect in STAT3 activation is detrimental in terms of liver injury, hepatocyte apoptosis and liver fibrosis, indicating the hepato-protective role of IL-6 signaling in this severe NASH model.     

TGFbeta-dependent gene expression profile during maturation of dendritic cells

Primary immune response to pathogens involves the maturation of antigen-presenting dendritic cells (DC). Bacterial lipopolysacharride (LPS) is a potent inducer of DC maturation, whereas the transforming growth factor beta (TGFbeta) attenuates much of this process. Here, we analyzed the global gene expression pattern in LPS-treated bone marrow derived DC during inhibition of their maturation process by TGFbeta. Exposure of DC to LPS induces a pronounced cell response, manifested in altered expression of a large number of genes. Interestingly, TGFbeta did not affect most of the LPS responding genes. Nevertheless, analysis identified a subset of genes that did respond to TGFbeta, among them the two inflammatory cytokines interleukin (IL)-12 and IL-18. Expression of IL-12, the major proinflammatory cytokine secreted by mature DC, was downregulated by TGFbeta, whereas the expression level of the proinflammatory cytokine IL-18, known to potentiate the IL-12 effect, was upregulated. Expression of the peroxisome proliferator-activated receptor gamma (PPARgamma) increased in response to TGFbeta, concomitantly with reduced expression of chemokine receptor 7 (CCR7). This finding supports the possibility that TGFbeta-dependent inhibition of CCR7 expression in DC is mediated by PPARgamma.     

The KSHV viral IL-6 homolog is sufficient to induce blood to lymphatic endothelial cell differentiation

The predominant tumor cell of Kaposi's Sarcoma (KS) is the spindle cell, a cell of endothelial origin that expresses markers of lymphatic endothelium. In culture, Kaposi's Sarcoma-associated herpesvirus (KSHV) infection of blood endothelial cells drives expression of lymphatic endothelial cell specific markers, in a process that requires activation of the gp130 receptor and the JAK2/STAT3 and PI3K/AKT signaling pathways. While expression of each of the KSHV major latent genes in endothelial cells failed to increase expression of lymphatic markers, the viral homolog of human IL-6 (vIL-6) was sufficient for induction and requires the JAK2/STAT3 and PI3K/AKT pathways. Therefore, activation of gp130 and downstream signaling by vIL-6 is sufficient to drive blood to lymphatic endothelial cell differentiation. While sufficient, vIL-6 is not necessary for lymphatic reprogramming in the context of viral infection. This indicates that multiple viral genes are involved and suggests a central importance of this pathway to KSHV pathogenesis.     

CD25 Blockade protects T Cells from Activation-induced Cell Death (AICD) via Maintenance of TOSO Expression

CD25 monoclonal antibody binding to the α -chain of the Interleukin-2 (IL-2) receptor, blocks high-affinity IL-2 binding, thereby preventing complete T-cell activation and being of ample importance in transplantation medicine and potentially the treatment of autoimmune disease. However, CD25 antibodies do not only block T-cell activation but also prevent activation-induced cell death (AICD) attributing a dual function to IL-2. In this study, the modulation of the genomic expression profile of human peripheral blood mononuclear cells (PBMC) with therapeutic concentrations of humanized anti-CD25 mAb was investigated. PBMC were stimulated with CD3 antibody OKT-3 together with recombinant IL-2 in the absence or presence of anti-CD25 mAb. RNA was extracted and subjected to microarray analysis on U133A microarrays (Affymetrix). Anti-CD25 treatment inhibited several genes typically expressed during T-cell activation including granzyme B, signalling lymphocyte activation molecule, family member 1 (SLAMF1), CD40-Ligand (CD40-L), IL-9 and interferon (IFN)- γ . Interestingly, anti-CD25 mAb also blocked the expression of several genes important for susceptibility to apoptosis, such as death receptor 6 (DR6) or reversed IL-2-mediated repression of anti-apoptotic genes, such as Fas apoptotic inhibitory molecule 3 (FAIM3)/TOSO. Functional significance of DR6 and TOSO expression in IL-2-dependent T-cell activation was subsequently evaluated by RNA interference in AICD: While siRNA specifically directed against DR6 did not modulate FAS-L-mediated apoptosis induction in primary T cells, down-regulation of TOSO significantly increased susceptibility to apoptosis, emphasizing an important role for TOSO in IL-2-mediated AICD.     

Constitutive activation of Stat3 signaling confers resistance to apoptosis in human U266 myeloma cells

Interleukin 6 (IL-6) is the major survival factor for myeloma tumor cells and induces signaling through the STAT proteins. We report that one STAT family member, Stat3, is constitutively activated in bone marrow mononuclear cells from patients with multiple myeloma and in the IL-6-dependent human myeloma cell line U266. Moreover, U266 cells are inherently resistant to Fas-mediated apoptosis and express high levels of the antiapoptotic protein Bcl-xL. Blocking IL-6 receptor signaling from Janus kinases to the Stat3 protein inhibits Bcl-xL expression and induces apoptosis, demonstrating that Stat3 signaling is essential for the survival of myeloma tumor cells. These findings provide evidence that constitutively activated Stat3 signaling contributes to the pathogenesis of multiple myeloma by preventing apoptosis.     

干扰STAT3基因对哮喘气道损伤的影响

目的:探讨信号转导及转录激活因子3(STAT3)在哮喘气道损伤中的作用及相关机制。方法:首先,通过Western blot检测哮喘患者的支气管黏膜组织中STAT3的表达及活化情况;其次,以支气管上皮细胞为研究对象,检测屋尘螨抗原P1(Derp1)刺激对STAT3的表达及活化的影响;再次,采用shRNA干扰支气管上皮细胞中STAT3的表达,CCK-8实验检测细胞活力,同时检测细胞培养液中肿瘤坏死因子α(TNF-α)、白细胞介素1β(IL-1β)和IL-6的含量来反映细胞的炎症反应,检测细胞中丙二醛(MDA)的含量及超氧化物歧化酶(SOD)和谷胱甘肽过氧化物酶(GSH-Px)的活性来反映细胞氧化应激水平;流式细胞术检测细胞凋亡情况。结果:哮喘患者的支气管黏膜组织中p-STAT3的蛋白水平显著上升,Derp1刺激可显著上调支气管上皮细胞中p-STAT3的蛋白水平。沉默STAT3可抑制TNF-α、IL-1β和IL-6释放,降低MDA的含量,升高SOD和GSH-Px的活性,并抑制细胞凋亡,提高细胞活力(P0.05)。结论:沉默STAT3可减轻尘螨诱导的气道损伤,其作用机制可能是通过抑制JAK/STAT信号通路的激活,抑制支气管上皮细胞分泌炎症细胞因子及细胞内氧化应激反应,进而减少细胞凋亡。