EGCG对LPS刺激人肺腺癌A549细胞凋亡及CUGBP1蛋白表达的影响

目的:研究表没食子儿茶素-3-没食子酸酯(epigallocatechin-3-gallate,EGCG)对炎性刺激的人肺腺癌A549细胞增殖和凋亡的影响及与CUGBP1表达的关系。方法:MTT法检测EGCG和LPS刺激A549细胞增殖活性的影响;流式细胞仪检测细胞凋亡;免疫细胞化学检测EGCG对LPS刺激人肺腺癌A549细胞内CUGBP1蛋白的表达。结果:与对照组相比,LPS体外显著促进A549细胞增殖,其胞核胞质内CUGBP1表达明显增强(P0.01)。加入EGCG可拮抗LPS促A549细胞增殖的作用,促进其凋亡,明显抑制LPS刺激的A549细胞内CUGBP1的表达(P0.01)。CUGBP1蛋白定量分析可知EGCG和LPS共同孵育A549细胞4h、24h时,细胞中的CUGBP1蛋白表达量较单纯LPS作用时降低。但EGCG和LPS共同孵育A549细胞24h,A549细胞中胞核CUGBP1蛋白表达量(1210.565±3.46)较4h时胞核CUGBP1蛋白表达量(67.344±3.68)高,差异有统计学意义(t=927.164,P0.001)。结论:EGCG可能通过干扰CUGBP1基因的表达抑制炎症刺激人肺腺癌细胞A549的增殖,促进其凋亡。     

木黄酮对人催乳素瘤细胞增殖及其凋亡影响的实验研究

目的观察木黄酮(genistein,GST)对培养的人垂体催乳素瘤细胞增殖和凋亡的影响。方法将GST、β-雌二醇(E2)作用于体外培养的人催乳素瘤细胞,测定MTT值及3H-TdR掺入量,流式细胞仪测定细胞周期,并用TUNEL法观察细胞凋亡情况。结果不同浓度的GST可抑制催乳素瘤细胞的增殖,并存在着剂量效应,10-5mol*L-1GST可使G1期的细胞比例从对照组的55.3%上升为90.3%;不同浓度的E2以剂量依赖方式刺激催乳素瘤细胞的增殖,并使G2期的细胞比例从对照组的15.6%上升为41.8%。GST和E2的共同作用仍可抑制催乳素瘤细胞的增殖,但抑制程度降低。不同浓度的GST均明显促进催乳素瘤细胞的凋亡,E2对GST的促凋亡作用无明显影响。结论GST在体外能明显抑制培养人催乳素瘤细胞的增殖,并促进其凋亡。E2可部分拮抗GST的抑制增殖作用,但对其促凋亡作用无明显影响。     

视黄醇结合蛋白4 对血管平滑肌细胞迁移和增殖的影响及机制

目的:研究视黄醇结合蛋白4(Retinol-binding protein 4,RBP4)对血管平滑肌细胞(SMCs)迁移和增殖的影响及分子机制。方法:体外培养大鼠主动脉SMCs,采用划痕实验及Boyden's迁移小室实验观察RBP4对SMCs迁移的影响,采用免疫印迹实验技术检测Akt的磷酸化水平,采用Boyden's小室实验观察PI3K抑制剂LY294002预处理细胞对RBP4促SMCs迁移的影响,应用MTT比色实验结合流式细胞仪技术,检测RBP4对SMCs细胞增殖及细胞周期的影响。结果:RBP4呈剂量依赖性诱导大鼠血管SMCs迁移(P0.05);RBP4处理细胞显著增加了Akt磷酸化;PI3K抑制剂LY294002预处理细胞则显著抑制了RBP4的促迁移作用(P0.05);RBP4处理有增加SMCs数量的趋势,且可轻微阻滞细胞进入S期,但未达到统计学显著性(P0.05)。结论:RBP4通过PI3K-Akt通路诱导大鼠血管SMCs迁移,对细胞增殖及细胞周期则无显著影响。     

木黄酮对人催乳素瘤细胞增殖及其凋亡影响的实验研究

目的：观察木黄酮（genistein,GST)对培养的人垂体催乳素瘤细胞增殖和凋亡的影响。方法：将CST、β-雌二醇（E2）作用于体外培养的人催乳素瘤细胞,测定MTT值及^3H-TdR掺入量,流式细胞仪测定细胞周期,并用TUNEL法观察细胞凋亡情况。结果：不同浓度的GST可抑制催乳素瘤细胞的增殖,并存在着剂量效应,10^-5mol.L^-1GST可使G1期的细胞比例从对照组的55.3%上升为90.3%;不同浓度的E2以剂量依赖方式刺激催乳素瘤细胞的增殖,并使G2期的细胞比例从对照组的15.6%上升为41.8%,GST和E2的共同作用仍可抑制催乳素瘤细胞的增殖,但抑制程度降低,不同浓度的GST均明显促进催乳素瘤细胞的凋亡,E2对GST的促凋亡作用无明显影响。结论：GST在体外能明显抑制培养人催乳素瘤细胞的增殖,并促进其凋亡,E2可部分拮抗GST的抑制增殖作用,但对其促凋亡作用无明显影响。     

EGCG对LPS刺激人肺腺癌A549细胞凋亡及CUGBP1蛋白表达的影响

目的：研究表没食子儿茶素-3-没食子酸酯（epigallocatechin-3-gallate,EGCG）对炎性刺激的人肺腺癌A549细胞增殖和凋亡的影响及与CUGBP1表达的关系。方法：MTT法检测EGCG和LPS刺激A549细胞增殖活性的影响;流式细胞仪检测细胞凋亡;免疫细胞化学检测EGCG对LPS刺激人肺腺癌A549细胞内CUGBP1蛋白的表达。结果：与对照组相比,LPS体外显著促进A549细胞增殖,其胞核胞质内CUGBP1表达明显增强（P〈0.01）。加入EGCG可拮抗LPS促A549细胞增殖的作用,促进其凋亡,明显抑制LPS刺激的A549细胞内CUGBP1的表达（P〈0.01）。CUGBP1蛋白定量分析可知EGCG和LPS共同孵育A549细胞4h、24h时,细胞中的CUGBP1蛋白表达量较单纯LPS作用时降低。但EGCG和LPS共同孵育A549细胞24h,A549细胞中胞核CUGBP1蛋白表达量（1210.565±3.46）较4h时胞核CUGBP1蛋白表达量（67.344±3.68）高,差异有统计学意义（t=927.164,P〈0.001）。结论：EGCG可能通过干扰CUGBP1基因的表达抑制炎症刺激人肺腺癌细胞A549的增殖,促进其凋亡。     

肿瘤坏死因子样弱凋亡诱导因子对人肝星状细胞生物学行为的影响

目的:观察肿瘤坏死因子样弱凋亡诱导因子(TWEAK)对人肝星状细胞(HSCs)株LX-2增殖、细胞周期、细胞凋亡、迁移及粘附能力的影响。方法:用不同浓度TWEAK培养LX-2细胞24或48 h,采用CCK-8法检测TWEAK对LX-2细胞增殖的影响,流式细胞术检测TWEAK对LX-2细胞周期和凋亡的影响,Transwell小室检测TWEAK对LX-2细胞迁移能力的影响,Matrigel基质胶检测TWEAK对LX-2细胞的粘附能力的影响。结果:与对照组相比,40 ng/m L和100 ng/m L TWEAK都能使LX-2细胞的迁移能力增强(P0.05),且100 ng/m L较40 ng/m L作用更强(P0.01);100 ng/m L TWEAK能够明显抑制LX-2细胞的粘附能力(P0.0001);40 ng/m L、100 ng/m L TWEAK对LX-2细胞的增殖、周期及凋亡无明显影响(P0.05)。结论:TWEAK能够增强LX-2细胞迁移能力,抑制其粘附能力。     

肌动蛋白解聚对巨噬细胞TLRs的表达及细胞凋亡的影响

在肺癌等的癌细胞中,脂多糖(lipopolysaccharide, LPS)等致炎因子介导的促瘤效应涉及Toll样受体(Toll like receptors, TLRs)/纤维型肌动蛋白(fibrous actin, F-actin)通路。该研究探讨了外源性松胞菌素D(cytochalasin D, cytD)和细胞内源过表达的重组肌动蛋白解聚因子丝切蛋白(Cofilin-1)所诱导的肌动蛋白解聚对巨噬细胞TLR2、TLR4和TLR9的表达和细胞凋亡水平的影响。分别用6种不同浓度的cytD处理RAW264.7小鼠巨噬细胞48 h,用Western blot检测6组细胞TLR2、TLR4、TLR9的表达水平。构建重组pEGFP-N1-Cofilin-1质粒并转染RAW264.7细胞,设置空质粒对照和空白细胞对照组。用Real-time PCR法和Western blot检测细胞转染前后Cofilin-1表达水平;Western blot检测巨噬细胞TLR2、TLR4、TLR9的表达情况;用流式细胞术检测3组细胞的凋亡水平。结果显示,终浓度≥1.5μmol/L的cytD处理细胞后, RAW264.7细胞表达TLR2明显降低(P0.05);终浓度≥1.0μmol/L的cytD处理细胞后,巨噬细胞表达TLR4、TLR9明显降低(P0.05)。重组质粒转染组细胞的cofilin-1 mRNA及Cofilin-1蛋白水平均高于空质粒对照组和空白细胞对照组(P0.05),且其TLR2、TLR4、TLR9蛋白表达水平和细胞凋亡水平均显著低于空质粒对照组和空白细胞对照组(P0.05)。结果表明,外源性cytD和巨噬细胞内源性高表达的Cofilin-1蛋白均可下调巨噬细胞TLR2、TLR4、TLR9的表达,其中,细胞高表达的Cofilin-1蛋白还显著降低了细胞凋亡率。该文通过揭示肌动蛋白解聚对巨噬细胞TLRs的表达及细胞凋亡的抑制,为进一步研究炎症与肿瘤的关系及分子机制奠定了基础。     

双歧杆菌脂磷壁酸对结肠癌细胞抑制增殖和促凋亡的研究

目的 探讨双歧杆菌脂磷壁酸(lipoteichoic acid,LTA)抑制人类结肠癌细胞株HCT116细胞增殖和促进凋亡情况.方法 培养结肠癌细胞株HCT116和提取双歧杆菌LTA;实验分为4组,即LTA低剂量组(20 μg/mL)、中剂量(60 μg/mL)、高剂量(100μg/mL)和HCT116对照组(Control);用四甲基偶氮唑蓝法(MTT)检测LTA对结肠癌细胞增殖的抑制率,流式细胞仪检测LTA对结肠癌细胞周期分布变化和凋亡率,免疫组化分析bcl-2、Cytochrome C和NF-kBp65含量变化,RT-PCR检测TLR2mRNA和TLR4m RNA的表达.结果 MTT法测得LTA各组对结肠癌细胞HCT116均具有较好的抑制(P＜0.01);流式细胞仪检得G0/G1期细胞显著增多(P＜0.01),而G2和S期细胞减少(P＜0.05),细胞凋亡率增加(P＜0.05);免疫组化分析IOD/Area值,bcl-2和NF-kBp65表达显著下调,Cytochrome C显著上升(P＜0.05);RT-PCR测得TLR2 mRNA和TLR4 mRNA的表达均上升(P＜0.05).结论 LTA具有明显的抑制结肠癌细胞增殖和促进凋亡作用,为研制高效、无毒的新型抗结肠癌药物奠定一定的基础.     

共轭亚油酸诱导人结肠癌细胞Caco-2凋亡的作用

共轭亚油酸（conjugated linoleic acid,CLA）有着多种异构体以及多种生理活性,如抗癌、减肥、抗动脉粥样硬化等。本研究主要对c9,t11-CLA和t9,t11-CLA两种异构体的混合物诱导人结肠癌细胞Caco-2凋亡的作用及可能机制进行了探讨。采用MTT方法、透射电镜观察、流式细胞术检测和RT—PCR方法,研究了CLA混合物抑制Caco-2细胞增殖,诱导Caco-2细胞凋亡的作用及可能机制。实验结果证明,c9,t11-CLA和t9,t11-CLA混合物能抑制Caco-2细胞的增殖,并可诱导Caco-2的凋亡。随着所用的CLA混合物浓度的增加以及作用时间的延长,细胞凋亡率增加。通过RT—PCR分析,Caco-2细胞中的caspase 3的mRNA的表达随着CLA混合物浓度的增加而上调。这两种CLA的混合物可抑制Caco-2细胞的增殖,诱导Caco-2的凋亡,而caspase 3的表达上调可能与细胞凋亡密切相关。     

凋亡素2配体对放射线诱导95-D细胞凋亡的影响的研究

目的:探讨凋亡素2配体(Apo-2L)对放射线诱导肺癌95-D细胞凋亡的影响。方法:MTT法检测不同浓度凋亡素2配体在体外对肺癌95-D细胞的抑制率,将细胞分为4组,对照组、凋亡素2配体组、单纯照射组、凋亡素2配体+放射照射组,流式细胞仪检测各组凋亡率及细胞周期。结果:凋亡素2配体对95-D细胞的体外抑制作用明显,随着药物浓度的增大及时间的延长,抑制率明显增高(P0.05)。流式细胞术显示凋亡素2配体与放射线联用能够使95-D细胞的凋亡率提高,与单用凋亡素2配体组及单纯放疗组相比,凋亡率差异显著(P0.05)。结论:凋亡素2配体在体外具有抑制95-D细胞增殖的作用并能够促进细胞的凋亡,同时凋亡素2配体联合放射线可以明显提高肺癌95-D细胞的凋亡率。     

Effects of azathioprine and its metabolites on repair mechanisms of the intestinal epithelium in vitro

Erosions and ulcerations of the intestinal epithelium are hallmarks of inflammatory bowel diseases (IBD). Intestinal epithelial cell migration (restitution) and proliferation are pivotal mechanisms for healing of epithelial defects after mucosal injury. In addition, the rate of apoptosis of epithelial cells may modulate intestinal wound healing. The purine antagonists azathioprine (AZA) and 6-mercaptopurine (6-MP) are widely used drugs in the treatment of IBD. In the present study, the hitherto unknown effects of AZA as well as its metabolites 6-MP and 6-thioguanine (6-TG) on repair mechanisms and apoptosis of intestinal epithelia were analysed. Intestinal epithelial cell lines (human Caco-2, T-84 and HT-29 cells, rat IEC-6 cells) were incubated with AZA, 6-MP or 6-TG for 24 h (final concentrations 0.1-10 microM). Migration of Caco-2 and IEC-6 cells was analysed by in vitro restitution assays. Caco-2 and IEC-6 cell proliferation was evaluated by measurement of [3H]thymidine incorporation into DNA. Apoptosis of Caco-2, T-84, HT-29 and IEC-6 cells was assessed by histone ELISA, 4'6'diamidino-2'phenylindole-dihydrochloride staining as well as flow cytometric analysis of Annexin V/propidium iodide (PI)-stained cells. Cell cycle progression was evaluated by PI staining and flow cytometry. Epithelial restitution was not significantly affected by any of the substances tested. However, proliferation of intestinal epithelial cells was inhibited in a dose-dependent manner (maximal effect 92%) by AZA, 6-MP as well as 6-TG. In HT-29 cells, purine antagonist-effected inhibition of cell proliferation was explained by a cell cycle arrest in the G2 phase. In contrast, AZA, 6-MP and 6-TG induced no cell cycle arrest in Caco-2, T-84 and IEC-6 cells. AZA, 6-MP as well as 6-TG induced apoptosis in the non-transformed IEC-6 cell line but not in human Caco-2, T-84 and HT-29 cells. In summary, AZA and its metabolites exert no significant effect on intestinal epithelial restitution. However, they profoundly inhibit intestinal epithelial cell growth via various mechanisms: they cause a G2 cell cycle arrest in HT-29 cells, induce apoptosis in IEC-6 cells and dose-dependently inhibit intestinal epithelial proliferation.     

Activation of TLR4 signaling promotes gastric cancer progression by inducing mitochondrial ROS production

Chronic infection, such as Helicobacter pylori infection, has been associated with the development of gastric cancer (GC). Pathogen-associated molecular patterns can trigger inflammatory responses via Toll-like receptors (TLRs) in GC. Here we showed that Toll-like receptor 4 (TLR4) was highly expressed in GC cells and was associated with the aggressiveness of GC. The binding of lipopolysaccharide (LPS) to TLR4 on GC cells enhanced proliferation without affecting apoptosis. Higher level of reactive oxygen species (ROS) was induced after activation of TLR4 signaling in GC. Using oxidase inhibitors and antioxidants, we found that mitochondrial ROS (mROS) was major source of TLR4-stimulated ROS generation. This elevated mROS production can be inhibited by diphenylene iodonium (DPI), and the blocking of the mROS production rather than ROS neutralization resulted in cell cycle arrest and the loss of mitochondrial potential, which were plausible reason for decreased cell viability. Furthermore, the increased mROS owing to TLR4 signaling resulted in the activation of Akt phosphorylation and NF-κB p65 nuclear translocation. Altogether, these results reveal a novel pathway linking innate immune signaling to GC cell proliferation, implicate mROS as an important component of cell survival signals and further establish mitochondria as hubs for GC therapies.     

TLR4/P38/JNK信号通路在海马神经元凋亡中的作用

目的：探讨Toll样受体4（TLR4）/P38/JNK信号通路在海马神经元凋亡中的作用及其机制,为神经退行性疾病（ND）的发病机制与防治研究提供新的实验依据。方法：采用体外培养7 d的新生大鼠海马神经元,免疫荧光双标法鉴定海马神经元纯度。用TLR4配体脂多糖（LPS）或TLR4抗体预处理海马神经元,以激活或阻断TLR4的作用。实验1设正常对照组、LPS组及TLR4抗体+ LPS组;免疫荧光法检测P-P38,P-JNK的表达。实验2分为6组：正常对照组,LPS组,TLR4抗体+ LPS组,SB202190（抑制P38） + LPS组,SP600125（抑制JNK） + LPS组,PD98059（抑制ERK） + LPS组;分别用TLR4抗体、P38、JNK及ERK的抑制剂预处理海马神经元后再给以LPS刺激24 h,Western blot法检测Bcl-2,Bax,Active-caspase-3的表达变化;流式细胞术检测海马神经元凋亡率。结果：LPS组海马神经元P-P38、P-JNK的表达明显高于正常对照组（P < 0. 01）,TLR4抗体+ LPS组P-P38,P-JNK表达显著低于LPS组（P <0.01）。与正常对照组相比,LPS组海马神经元Bcl-2/Bax表达减少、Active-caspase-3表达增加,海马神经元凋亡率增加（P < 0.01）。而TLR4抗体+ LPS组、SB202190 + LPS组、SP600125 + LPS组Bcl-2/Bax显著高于LPS组、Active cas-pase-3显著低于LPS组（P < 0.01）,海马神经元凋亡率显著低于LPS组（P < 0. 05,P < 0. 01）。PD98059 + LPS组与LPS组海马神经元凋亡率无明显差异。结论：①海马神经元中有TLR4介导的P38/JNK信号通路。②海马神经元TLR4激活后,P-P38、P-JNK表达增加,使Bcl-2/Bax的比例降低和Active-caspase-3表达增加,从而促进海马神经元的凋亡。海马神经元凋亡过程中有TLR4介导的P38/JNK信号通路的参与。     

Cutting edge: T cells respond to lipopolysaccharide innately via TLR4 signaling

LPS, a molecule produced by Gram-negative bacteria, is known to activate both innate immune cells such as macrophages and adaptive immune B cells via TLR4 signaling. Although TLR4 is also expressed on T cells, LPS was observed not to affect T cell proliferation or cytokine secretion. We now report, however, that LPS can induce human T cells to adhere to fibronectin via TLR4 signaling. This response to LPS was confirmed in mouse T cells; functional TLR4 and MyD88 were required, but T cells from TLR2 knockout mice could respond to LPS. The human T cell response to LPS depended on protein kinase C signaling and involved the phosphorylation of the proline-rich tyrosine kinase (Pyk-2) and p38. LPS also up-regulated the T cell expression of suppressor of cytokine signaling 3, which led to inhibition of T cell chemotaxis toward the chemokine stromal cell-derived factor 1alpha (CXCL12). Thus, LPS, through TLR4 signaling, can affect T cell behavior in inflammation.     

The molecular mechanisms of the effect of Dexamethasone and Cyclosporin A on TLR4 /NF-κB signaling pathway activation in oral lichen planus

Toll-like receptors (TLRs) and the nuclear factor-kappa B (NF-κB) signaling transduction pathway play important roles in the pathogenesis of several chronic inflammatory diseases, but its function in oral lichen planus (OLP) remains unclear. In this study, we examined the expression of TLR4 and NF-κB-p65 and inflammatory cytokines TNF-α and IL-1β by immunohistochemistry in OLP tissues, and found that TLR4 and NF-κB-p65 were significantly upregulated in OLP compared to normal oral mucosa (P<0.05). We used keratinocytes HaCaT stimulated with lipopolysaccharide (LPS) to simulate the local OLP immune environment to some extent. RT-PCR and immunoblotting analyses showed significant activation of TLR4 and NF-κB-p65 in the circumstance of LPS-induced inflammatory response. The high expression of TLR4 and NF-κB-p65 are correlated with expression of cytokines TNF-α and IL-1β (P<0.05). We further showed that NF-κB could act as an anti-apoptotic molecule in OLP. We conclude that TLR4 and the NF-κB signaling pathway may interact with the perpetuation of OLP. Steroids and cyclosporine are effective in the treatment of symptomatic OLP. However, there was some weak evidence for the mechanism over Dexamethasone (DeX) and Cyclosporine A (CsA) for the palliation of symptomatic OLP. In the present study, we found that Dexamethasone and Cyclosporine A negatively regulated NF-κB signaling pathway under LPS simulation in HaCaT cells by inhibiting TLR4 expression, on the other hand, Cyclosporine A could inhibit HaCaT cell proliferation by the induction of the apoptosis of HaCaT cells to protect OLP from the destruction of epidermal cells effectively.     

Expression and Functional Analysis of Toll-like Receptor 4 in Human Cervical Carcinoma

Toll-like receptors are expressed in human immune cells and many tumors, but the role of toll-like receptor 4 (TLR4) in the development of tumors is controversial. We demonstrated the expression, distribution, and functional activity of TLR4 in tissues of normal cervix, cervical intraepithelial neoplasia (CIN), invasion cervical cancers (ICC), and different human papillomavirus (HPV)-infected cervical cancer cells. The results showed that TLR4 expression was in accordance with the histopathological grade: higher in ICC than in CIN, and low in normal cervical tissues and malignant cervical stroma. Expression was higher in SiHa (HPV16+) than in HeLa (HPV18+) cells, but was not observed in C33A (HPV?) cells. After treatment with its agonist, lipopolysaccharide (LPS), the expression levels of TLR4 was increased and apoptosis resistance was induced in SiHa cells, but not in HeLa or C33A cells. Meanwhile, LPS treatment did not alter the cell cycle distribution in SiHa cells. The mechanism of apoptosis resistance may be related to HPV16 infection and not correlated with the cell cycle distribution. Targeting TLR4 in combination with traditional drug treatment may serve as a novel strategy for more effectively killing cancer cells.     

NF-κB is involved in the LPS-mediated proliferation and apoptosis of MAC-T epithelial cells as part of the subacute ruminal acidosis response in cows

Objectives

To determine the effect of NF-κB on cell proliferation and apoptosis, we investigate the expression of inflammation and apoptosis-related factors in the bovine mammary epithelial cell line, MAC-T.

Results

MAC-T cells were cultured in vitro and MTT and LDH assays used to determine the effects of lipopolysaccharide (LPS) on proliferation and cytotoxicity respectively. RT-PCR and western blotting were used to evaluate the effect of LPS and NF-κB inhibition [pyrrolidine dithiocarbamate (PDTC) treatment] on the expression of inflammation and apoptosis-related factors. LPS significantly inhibited MAC-T cell proliferation in a dose- and time-dependent manner. Furthermore, LPS promoted apoptosis while the NF-кB inhibitor PDTC attenuated this effect. After LPS treatment, the NF-кB signaling pathway was activated, and the expression of inflammation and apoptosis-related factors increased. When PDTC blocked NF-кB signaling, the expression of inflammation and apoptosis-related factors were decreased in MAC-T cells.

Conclusions

LPS activates the TLR4/NF-κB signaling pathway, inhibits proliferation and promotes apoptosis in MAC-T cells. NF-кB inhibition attenuates MAC-T cell apoptosis and TLR4/NF-κB signaling pathway. NF-кB inhibitor alleviating MAC-T cell apoptosis is presumably modulated by NF-кB.

     

MD-2 controls bacterial lipopolysaccharide hyporesponsiveness in human intestinal epithelial cells

Intestinal epithelial cells (IEC) have adapted to the presence of commensal bacteria through a state of tolerance that involves a limited response to lipopolysaccharide (LPS). Low or absent expression of two LPS receptor molecules, the myeloid differentiation (MD)-2 receptor, and toll-like receptor (TLR)4 was suggested to underlie LPS tolerance in IEC. In the present study we performed transfections of TLR4 and MD-2 alone or combined in different IEC lines derived from intestinal cancer (Caco-2, HT-29, and SW837). We found that LPS responsiveness increased more than 100-fold when IEC were transfected with MD-2 alone, but not TLR4. The release of interleukin (IL)-8, but also the expression of cyclooxygenase (Cox-)2 and the related secretion of prostaglandin (PG)E2 were coordinately stimulated by LPS in IEC transfected with MD-2 alone. Supernatants collected from MD-2-transfected IEC supported LPS activation of naïve HT-29, providing additional support to the concept that MD-2 alone endows IEC with LPS responsiveness. LPS responsiveness detected at concentrations as low as 110 pg/ml, and maximal values obtained by 10 ng/ml were clearly beyond those evoked by classical stimuli as IL-1β. In polarized cells, apical LPS stimulation was markedly more efficient than basolateral. Our data contradict previous opinion that both TLR4 and MD-2 limit IEC response to LPS, and emphasize the prominent role of MD-2 in intestinal immune responses to Gram-negative bacteria.     

Cyclooxygenase-2 inhibition by novel Bisaryl imidazolyl imidazole derivatives increases Bax/Bcl-2 ratio and upregulates Caspase-3 gene expression in Caco-2 colorectal cancer cell line

Cyclooxygenase-2 (COX-2) inhibitors including celecoxib inhibit cell growth and induce apoptosis in cancer cells. In this study, the relation of Bax (an apoptosis promoter) to Bcl-2 (an apoptosis inhibitor) ratio with the apoptosis co-ordination enzyme, caspase-3 was investigated in correlation with the treatment of 4,5-bisaryl imidazolyl imidazoles as novel selective COX-2 inhibitors in Caco-2 colorectal cancer cells. Recently, the organic reactions under microwave irradiation attracted attention of scientists due to their high reaction rate, mild reaction conditions and the formation of clean products. Therefore, a microwave-assisted method was used to synthesize our compounds. The effects of these COX-2 inhibitors on the proliferation of Caco-2 cells were evaluated by MTT assay. cDNA microarray and clustering analysis were used to evaluate effects of our synthetic compounds on gene expression pattern of 112 genes involved in apoptosis pathways. Bax, Bcl-2 and caspase-3 mRNA expression and their relationship were analyzed by quantitative real-time PCR. Results indicated that proliferation of Caco-2 cells after treatment with 4,5-bisaryl imidazolyl imidazoles on Caco-2 cells were time and dose dependent. We conclude that increase in Bax/Bcl-2 ratio leads to an up-regulation in caspase-3 mRNA expression.