Induction of endoplasmic reticulum stress-mediated apoptosis and non-canonical autophagy by luteolin in NCI-H460 lung carcinoma cells

In this study, we investigated the anti-cancer effects of luteolin, a member of the flavonoid family, in NCI-H460 human lung carcinoma cells. It was shown that luteolin induces apoptotic cell death through modulating both the extrinsic pathway and intrinsic pathways, which are suppressed by z-VAD-fmk, indicating that luteolin triggers caspase-dependant apoptosis. Furthermore, we found that the α subunit of the eukaryotic initiation factor 2 (eIF2α/C/EBP homologous protein pathway, but not the c-Jun N-terminal kinase pathway, played a critical role in induction of apoptosis by luteolin. The data indicated that luteolin also induces autophagy; evidence for this is the accumulation of microtubule-associated protein light chain-3 (LC3) II protein, the increase of LC3 puncta as well as an enhanced autophagy flux. In addition, inhibiting autophagy by bafilomycin A1 reduced apoptotic cell death, suggesting that luteolin-induced autophagy functions as a cell death mechanism. Notably, the activated caspases that appeared with luteolin treatment cleaved Beclin-1, and the expression of LC3II remained the same even after cells were challenged with Beclin-1 siRNA, demonstrating that luteolin induces Beclin-1-independent autophagy. Taken together, our findings showed that luteolin triggers both endoplasmic reticulum stress-related apoptosis and non-canonical autophagy, which function as a cell death mechanism in NCI-H460 human lung cancer cells.     

木犀草素抑制PKM2继而促进自噬诱导肝癌细胞凋亡

目的：探究木犀草素对人肝癌HepG2细胞中PKM2表达的影响，继而挖掘木犀草素诱导肝癌细胞凋亡的机制。方法：通过数据库比较肝癌的癌旁组织和肿瘤组织中的PKM2表达差异，收集肝癌患者标本，检测癌和癌旁组织中PKM2 mRNA和蛋白的表达差异。木犀草素刺激肝癌细胞HepG2，用CCK8、流式凋亡及Western blot方法检测木犀草素对肝癌生存率和凋亡的影响，以及木犀草素作用于肝癌细胞后PKM2的变化。在肝癌细胞系中敲减或过表达PKM2，用木犀草素刺激肝癌细胞，探究PKM2对木犀草素诱导肝癌细胞增殖和凋亡的影响，同时检测自噬相关分子，探究PKM2及木犀草素对自噬的影响。结果：与癌旁组织相比，肿瘤组织中PKM2表达量升高；木犀草素以浓度依赖性和时间依赖性抑制HepG2细胞增殖，诱导细胞凋亡，并且随着木犀草素浓度的增高PKM2的表达逐渐降低；敲减PKM2可以显著抑制肝癌细胞增殖，促进肝癌细胞凋亡，而过表达PKM2可以削弱木犀草素对肝癌细胞的凋亡作用。木犀草素可以促进肝癌细胞自噬，敲减PKM2后可以抑制木犀草素诱导的自噬。结论：木犀草素可以通过抑制PKM2表达，诱导肝癌细胞发生自噬，促进细胞凋亡。     

二萜类化合物excisanin A诱导人结肠癌SW620细胞凋亡及机制研究

目的本文研究大萼香茶菜有效单体exc isan in A诱导人结肠癌SW 620细胞株凋亡及其分子机制。方法MTT法检测细胞增殖抑制作用,AnnexinV/PI双染法检测细胞早期凋亡率,W estern b lot法检测exc isan in A对PARP、caspase-3、caspase-9剪切片断的影响,及对MAPKs通路相关蛋白,包括p-ERK、ERK、p-JNK、JNK、p-p38、p38、c-Jun表达的影响。结果Excisanin A对结肠癌SW620细胞株生长具有明显的抑制作用,并呈浓度依赖性,其IC50值为8.22μmol.L-1。用8.71μmol.L-1excisanin A处理SW620细胞12、24、36 h,AnnexinV/PI双染检测细胞的早期凋亡,其凋亡率分别为17.2%、20.5%、13.8%,而对照组细胞的凋亡率仅为1.9%(P<0.05)。不同浓度的excisanin A作用于SW620细胞48h后,Western blot法检测发现PARP、caspase-3,caspase-9 3种蛋白均出现断裂片断,并随着浓度的增加断裂更明显。进一步研究发现,excisanin A处理SW620细胞后,JNK、p38的磷酸化水平明显升高,c-Jun的表达亦增高。结论Excisa-nin A具有明显的细胞毒作用,能诱导SW620细胞凋亡,JNK和p38途径的激活可能是其诱导凋亡的分子机制之一。     

Luteolin shows an antidepressant-like effect via suppressing endoplasmic reticulum stress

Depression is a significant public health problem and some reports indicate an association between depression and endoplasmic reticulum stress. Luteolin is a flavonoid contained in many plants and with a variety of known pharmacological properties such as anti-inflammatory, anti-anxiety, and memory-improving effects, suggesting that luteolin penetrates into the brain. In the present study, we investigated the effects of luteolin on endoplasmic reticulum stress-induced neuronal cell death. Luteolin significantly suppressed tunicamycin-induced cell death at 1 to 10 μM in human neuroblastoma cells. Luteolin increased in the expression of the 78 kDa glucose-regulated protein and 94 kDa glucose-regulated protein and decreased in the cleavage activation of caspase-3. Additionally, to investigate whether chronic luteolin treatment has an antidepression effect, we performed some behavioral tests. Chronic luteolin treatment showed antidepressant-like effects in behavioral tests and, luteolin attenuated the expression of endoplasmic reticulum stress-related proteins in the hippocampus of corticosterone-treated depression model mice. These findings indicate that luteolin has antidepressant-like effects, partly due to the suppression of endoplasmic reticulum stress.     

Luteolin prevents PDGF-BB-induced proliferation of vascular smooth muscle cells by inhibition of PDGF beta-receptor phosphorylation

Luteolin occurs as glycosylated forms in celery, green pepper, perilla leaf and camomile tea, and has been shown to possess antimutagenic, antitumorigenic, antioxidant and antiinflammatory properties. In this study, we have investigated the antiproliferable effect and its mechanism of luteolin on platelet-derived growth factor (PDGF)-BB-induced proliferation of rat aortic vascular smooth muscle cells (VSMCs). Luteolin significantly inhibited PDGF-BB-induced proliferation and DNA synthesis of rat aortic VSMCs in a concentration-dependent manner. In addition, flow cytometry analysis of DNA content revealed blocking of the PDGF-BB-inducible cell cycle progression by luteolin. Pre-incubation of rat aortic VSMCs with luteolin significantly inhibited the PDGF-BB-induced extracellular signal-regulated kinase 1/2 (ERK1/2), Akt and phospholipase C (PLC)-gamma1 activation as well as c-fos gene expression. Consisted with these findings, luteolin inhibited PDGF-Rbeta phosphorylation induced by PDGF-BB in a concentration-dependent manner. These results suggest that the inhibitory effect of luteolin on the PDGF-BB-induced proliferation of rat aortic VSMCs may be mediated by blocking phosphorylation of PDGF-Rbeta.     

Luteolin protects osteoblastic MC3T3-E1 cells from antimycin A-induced cytotoxicity through the improved mitochondrial function and activation of PI3K/Akt/CREB

Luteolin is a flavonoid found in many herbal extracts including celery, green pepper, parsley, perilla leaf and seeds, and chamomile. Antimycin A (AMA) is an inhibitor of the mitochondrial electron transport chain. In the present study, the protective effect of luteolin on AMA-induced cell damage was investigated in osteoblastic MC3T3-E1 cells. Luteolin significantly increased the viability of MC3T3-E1 cells in the presence of AMA and the effect of luteolin in increasing cell viability was completely prevented by the presence of LY294002, Akt inhibitor, or auranofin, suggesting that the effect of luteolin might be partly mediated from PI3K, Akt, and thioredoxin reductase. Pre-treatment with luteolin prior to AMA exposure significantly prevented mitochondrial membrane potential dissipation, ATP loss, inactivation of complex I and IV, ROS production, inactivation of thioredoxin reductase, intracellular calcium elevation, and cytochrome c release induced by AMA. Moreover, luteolin increased activities of PI3K (phosphoinositide 3-kinase) and Akt (protein kinase B), and CREB (cAMP-response element-binding protein) phosphorylation inhibited by AMA treatment. Collectively, these results suggest that luteolin protects MC3T3-E1 cells from AMA-induced cell damage through the improved mitochondrial function and activation of PI3K/Akt/CREB.     

Luteolin and chicoric acid synergistically inhibited inflammatory responses via inactivation of PI3K-Akt pathway and impairment of NF-κB translocation in LPS stimulated RAW 264.7 cells

Synergistic anti-inflammatory effects of luteolin and chicoric acid, two abundant constituents of the common dandelion (Taraxacum officinale Weber), were investigated in lipopolysaccharide (LPS) stimulated RAW 264.7 cells. Co-treatment with luteolin and chicoric acid synergistically reduced cellular concentrations of nitric oxide (NO) and prostaglandin E2 (PGE2) and also inhibited expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). In addition, co-treatment reduced the levels of proinflammatory cytokines, tumor necrosis factor (TNF)-α, and interleukin (IL)-1β. Both luteolin and chicoric acid suppressed oxidative stress, but they did not exhibit any synergistic activity. Luteolin and chicoric acid co-treatment inhibited phosphorylation of NF-κB and Akt, but had no effect on extracellular signal-regulated kinase (ERK), c-Jun NH2-terminal kinase (JNK), and p38. This anti-inflammatory signaling cascade coincides with that affected by luteolin treatment alone. These results suggest that luteolin plays a central role in ameliorating LPS-induced inflammatory cascades via inactivation of the NF-κB and Akt pathways, and that chicoric acid strengthens the anti-inflammatory activity of luteolin through NF-κB attenuation.     

A critical role of luteolin-induced reactive oxygen species in blockage of tumor necrosis factor-activated nuclear factor-kappaB pathway and sensitization of apoptosis in lung cancer cells

Nuclear factor kappaB (NF-kappaB) activated by tumor necrosis factor (TNF) attenuates the TNF-induced apoptosis pathway. Therefore, blockage of NF-kappaB should improve the anticancer activity of TNF. Luteolin, a naturally occurring polyphenol flavonoid, has been reported to sensitize colorectal cancer cells to TNF-induced apoptosis through suppression of NF-kappaB; however, the mechanisms of this effect have not been well elucidated. In this article, we provide evidence showing a critical role of reactive oxygen species (ROS) accumulation induced by luteolin in modulating TNF-activated pathways in lung cancer cells. Luteolin effectively suppressed NF-kappaB, whereas it potentiated the c-Jun N-terminal kinase (JNK) to increase apoptosis induced by TNF in lung cancer cells. Our results further demonstrate that luteolin induced an early phase ROS accumulation via suppression of the cellular superoxide dismutase activity. It is noteworthy that suppression of ROS accumulation by ROS scavengers butylated hydroxyanisole, and N-acetyl-L-cysteine prevented the luteolin-induced suppression of NF-kappaB and potentiation of JNK and significantly suppressed the synergistic cytotoxicity seen with cotreatment of luteolin and TNF. Taken together, these results suggest that the accumulation of ROS induced by luteolin plays a pivotal role in suppression of NF-kappaB and potentiation of JNK to sensitize lung cancer cells to undergo TNF-induced apoptosis.     

Luteolin inhibits apoptosis and improves cardiomyocyte contractile function through the PI3K/Akt pathway in simulated ischemia/reperfusion

Luteolin, a naturally occurring polyphenol flavonoid, has demonstrated to exert myocardial protection effects. However, the mechanisms have not been fully elucidated. In the present study, we investigated whether luteolin pretreatment was associated with cardioprotection in a rat ischemia/reperfusion (I/R) model. Luteolin significantly not only restored contractility of the left ventricle, but also reduced the infarct size and lactate dehydrogenase leakage during I/R. In addition, luteolin pretreatment significantly improved cardiomyocyte shortening amplitude, decreased the apoptotic rate, upregulated Bcl-2 expression, downregulated Bax expression and raised the Bcl-2/Bax ratio under a simulated ischemia/reperfusion (SI/R) condition. Moreover, luteolin pretreatment increased protein kinase B (Akt) phosphorylation, phospholamban phosphorylation and the expression of sarcoplasmic reticulum calcium ATPase following SI/R. The phosphoinositide 3-kinase (PI3K)/Akt pathway is one of the most important intracellular survival signal pathways. To determine whether luteolin-induced cardioprotection was mediated by the PI3K/Akt pathway, we utilized the PI3K inhibitor LY294002. Inhibition of Akt activity markedly abolished luteolin-induced positive contraction and inhibition of apoptosis in SI/R cardiomyocytes. These results showed that luteolin inhibits apoptosis and improves cardiomyocyte contractile function at least partly through the PI3K/Akt pathway in SI/R.     

TEOA,a triterpenoid from <Emphasis Type="Italic">Actinidia eriantha</Emphasis>, induces autophagy in SW620 cells via endoplasmic reticulum stress and ROS-dependent mitophagy

2α,3α,24-Thrihydroxyurs-12-en-28-oicacid (TEOA), a pentacyclic triterpenoid, isolated from the roots of Actinidia eriantha, exhibits significant cytotoxicity against SW620, BGC-823, HepG-2, A549 and PC-3 cancer cells. In this study, we investigated the underlying molecular mechanism of the anticancer activity of TEOA in SW620 cells. We demonstrated that TEOA induced apoptosis through cleavage of caspase-9 and PARP in SW620 cells. In addition, evidence of TEOA-mediated autophagy included the induction of autophagolysosomes and activation of autophagic markers LC-3B and p62. Further analysis illustrated that TEOA promoted the phosphorylation of PERK and elF2α, followed by up-regulation of the downstream protein CHOP, suggesting the involvement of PERK/eIF2α/CHOP pathway and ER stress in TEOA-induced autophagy in SW620 cells. Meanwhile, TEOA-mediated PINK1, Parkin, ubiquitin and p62 activation revealed that TEOA induced specific autophagy-mitophagy in SW620 cells. Additionally, an antioxidant NAC attenuated the TEOA-induced mitophagy, indicating that TEOA triggers mitophagy via a ROS-dependent pathway. Collectively, our findings revealed a novel cellular mechanism of TEOA in the colon cancer cell line SW620, thus providing a molecular basis for developing TEOA into an anti-tumor candidate.     

木犀草素抑制白血病耐药株K562/A02的GST-π表达

目的 探讨木犀草素(luteolin)对白血病耐药株K562/A02细胞谷胱甘肽S转移酶π(GST-π)的影响.方法 木犀草素30 mmol/L预处理K562/A02细胞第1、3、5d后,MTT法测定阿霉素IC50,采用722分光光度计测定细胞内GSH含量及Western Blot法测定木犀草素处理后GST-π蛋白表达.结果 木犀草素对K562/A02的耐药性具有明显的逆转作用,用木犀草素处理后,对阿霉素药物敏感性的相对逆转效率第1、3、5d分别为10.7％、42.7％和15.8％;木犀草素显著降低K562/A02细胞内GSH含量,GST-π蛋白的表达于用药后第1、3、5d分别下降22％、56％和34％.结论 木犀草素具有较强的逆转K562/A02细胞多药耐药的作用,其逆转机制可能与降低细胞内GSH含量,下调K562/A02细胞GST-π蛋白的表达相关.     

二甲双胍在结肠癌中通过抑制lncRNA-MALAT1的表达发挥抗肿瘤效应

目的 探讨二甲双胍（MET）对结肠癌细胞的抑制作用及其机制。方法 采用CCK-8、流式细胞术及Transwell检测MET对结肠癌细胞SW480和SW620增殖、凋亡及侵袭的影响,qRT-PCR检测5种lncRNA在结肠癌细胞中的表达,Western blotting检测MET和/或MALAT1基因敲减在体外对PI3K/AKT和ERK通路活性的影响。结果 MET在体外对SW480和SW620细胞具有抑制作用,且呈剂量和时间依赖性（P<0.05）。MET可促进SW480和SW620细胞凋亡（P<0.05）。在5种lncRNA中,lncRNA-MALAT1在SW480和SW620细胞中的表达水平最高（P<0.01）。siRNA可抑制lncRNA-MALAT1表达,并进一步增强MET介导的抗结肠癌作用（P<0.05）。MET可下调结肠癌细胞中lncRNA-MALAT1的表达（P<0.05）,并通过PI3K/AKT和ERK信号通路与lncRNA-MALAT1敲减协同抑制结肠癌细胞的增殖和侵袭,并促进其凋亡（P<0.01）。结论 MET在结肠癌细胞中通过抑制lncRNA-MALAT1的表达发挥抗肿瘤效应。     

Epigallocatechin-3-gallate inhibits proliferation and migration of human colon cancer SW620 cells in vitro

Aim:

Epigallocatechin-3-gallate (EGCG) is the major polyphenolic constituent in green tea. The aim of this study is to investigate the effects of EGCG on proliferation and migration of the human colon cancer SW620 cells.

Methods:

Proliferation and migration of SW620 cells were induced by the protease-activated receptor 2-agonist peptide (PAR2-AP, 100 μmol/L) or factor VIIa (10 nmol/L), and analyzed using MTT and Transwell assays, respectively. The cellular cytoskeleton was stained with rhodamine-conjugated phalloidin and examined with a laser scanning confocal fluorescence microscope. The expression of caspase-7, tissue factor (TF) and matrix metalloproteinase (MMP)-9 in the cells was examined using QT-PCR, ELISA and Western blot assays. The activation of extracellular signal-regulated kinase 1 and 2 (ERK1/2) and nuclear factor-kappa B (NF-κB) signaling pathways was analyzed with Western blot.

Results:

Both PAR2-AP and factor VIIa promoted SW620 cell proliferation and migration, and caused cytoskeleton reorganization (increased filopodia and pseudopodia). Pretreatment with EGCG (25, 50, 75, and 100 μg/mL) dose-dependently blocked the cell proliferation and migration induced by PAR2-AP or factor VIIa. EGCG (100 μg/mL) prevented the cytoskeleton changes induced by PAR2-AP or factor VIIa. EGCG (100 μg/mL) counteracted the down-regulation of caspase-7 expression and up-regulation of TF and MMP-9 expression in the cells treated with PAR2-AP or factor VIIa. Furthermore, it blocked the activation of ERK1/2 and NF-κB (p65/RelA) induced by PAR2-AP or factor VIIa.

Conclusion:

EGCG blocks the proliferation and migration of SW620 cells induced by PAR2-AP and factor VIIa via inhibition of the ERK1/2 and NF-κB pathways. The compound may serve as a preventive and therapeutic agent for colon cancers.     

丹参酮ⅡA磺酸钠对海水浸泡人肺泡上皮细胞钠钾三磷酸腺苷酶的影响

目的 探讨丹参酮ⅡA磺酸钠(STS)对海水浸泡人肺泡上皮A549细胞钠钾三磷酸腺苷酶(NKA)的影响,并研究细胞外信号调节激酶(ERK)信号通路在其中的作用.方法 将A549细胞随机分为正常组(NG组)、STS组(STS组)、海水组(SW组)、海水+STS组(SW+STS组)、海水+STS+ ERK抑制剂组(SW+ STS+ U0126组).分别以海水、STS及U0126按各组要求浸泡A549细胞,通过Westernblotting法检测各组NKAα1,NKAβ1,ERK1/2蛋白的表达,水解比色法检测NKA活性.结果 SW组的NKA表达及活性均较NG组明显下降,SW+ STS组的NKA活性、NKAα1及NDKβ1蛋白丰度较SW组明显增高,而SW+ STS+ U0126组NKA活性及表达均较SW+ STS组明显下降.结论 STS可抑制海水浸泡A549细胞后导致的NKA活性、NKAα1及NKAβ1蛋白表达的下降,而ERK信号通路在其中发挥了一定的作用.     

靶向沉默TrkB基因对结肠癌细胞SW620 失巢凋亡水平的影响

摘要： 目的 在结肠癌细胞SW620中靶向沉默神经营养因子酪氨酸激酶受体B （TrkB） 基因以探讨其对肿瘤细胞的失巢凋亡水平的影响。方法 构建TrkB慢病毒干扰载体, 使用TrkB-shRNA慢病毒感染SW620细胞, 利用实时定量PCR和Western blot法分别检测TrkB基因在mRNA和蛋白水平表达量的变化; 酶联免疫吸附试验 （ELISA） 检测下调TrkB基因表达后贴壁和悬浮生长状态下细胞失巢凋亡率的变化。结果 成功构建TrkB-shRNA慢病毒干扰载体,获得SW620-iTrkB稳定感染细胞系。与SW620-iLuc对照组相比, 转染SW620-iTrkB细胞中TrkB基因的mRNA和蛋白相对表达水平均降低 （P＜0.05）。不同生长状态和不同转染质粒转染均对SW620-iTrkB细胞的失巢凋亡水平有影响, 存在交互效应 （P＜0.05）。与贴壁状态相比, 悬浮状态下SW620-iLuc组和SW620-iTrkB组细胞凋亡率均明显上升 （P＜0.05）; 在悬浮状态下, SW620-iTrkB组细胞凋亡率明显高于SW620-iLuc组 （P＜0.05）。结论 慢病毒载体介导的TrkB-shRNA能在结肠癌细胞SW620中产生特异性的基因沉默效应, 显著增加细胞的失巢凋亡水平。     

Anti-oxidant and anti-apoptotic effects of luteolin on mice peritoneal macrophages stimulated by angiotensin II

PurposeLuteolin, a plant flavonoid, can be found in a variety of plants and possesses anti-tumorigenic, anti-mutagenic, anti-oxidant and anti-inflammatory properties. However, the protective effects of luteolin on mice peritoneal macrophages stimulated by Angiotensin II (Ang II) have not been fully elucidated.Methods and resultsMice peritoneal macrophages were confirmed to be strongly positive for the macrophage marker CD68. Cell viability was tested after cells were pretreated with different concentrations of luteolin (6.25, 12.5 and 25 μM) and stimulated by Ang II. Luteolin not only significantly increased the viability of macrophages in the presence of Ang II, but also decreased the apoptotic rate, up-regulated Bcl-2 expression, and down-regulated Bax expression, thereby raising the ratio of Bcl-2 to Bax. In addition, luteolin pretreatment significantly increased the activity of SOD and reduced the levels of malondialdehyde (MDA), which was up-regulated in the presence of Ang II. This protective effect was also seen with Vitamin E (VitE) pretreatment, which was used as a standard control in this study.ConclusionsThese data clearly demonstrate that luteolin suppresses Ang II-directed oxidative stress and apoptosis on mice peritoneal macrophages.     

Luteolin suppresses IL-31 production in IL-33-stimulated mast cells through MAPK and NF-κB signaling pathways

IL-31 and IL-33 are cytokines, which are expressed in many inflammatory and pathological disorders, thus suggesting an IL-31/IL-33 axis interaction in pathological diseases. Luteolin from natural products is known for its anti-inflammatory activities associated with the regulation of inflammatory signaling pathways. Here, we investigated the effects of luteolin in the regulation of IL-33-stimulated production and secretion of IL-31 in HMC-1.2 mast cells. Human mast cells (HMC-1.2) were treated with luteolin and stimulated with IL-33. Real-time PCR was used to measure IL-31 mRNA expression. Western blot and immunofluorescence assays were used to measure IL-31 expression. ELISA techniques were used to measure IL-31 secretion and NF-κB-DNA-binding activities. The results revealed that luteolin inhibited the expression of IL-31 in IL-33-stimulated HMC-1.2 cells at the mRNA and protein levels. Also, Luteolin inhibited the secretion of IL-31 into the cell culture media of the IL-33-stimulated HMC-1.2 cells. Further findings demonstrated that luteolin inhibited the activation of ERK, JNK, p38, and NF-κB p65 in the IL-33-stimulated HMC-1.2 cells. In addition, luteolin also prevented the nuclear translocation and binding of p65 to its DNA-binding site. Based on the results, luteolin may be considered as a potential therapeutic or functional food agent for the prevention and/or treatment of IL-31 and IL-33-related diseases.     

Inhibition of LPS-stimulated pathways in macrophages by the flavonoid luteolin

1: We have previously shown that the flavonoid luteolin inhibits the expression of pro-inflammatory molecules induced by LPS. In the present study we tested the ability of luteolin to block signalling pathways implicated in LPS-induced inflammatory gene expression in macrophages. 2: Exposure of the murine macrophage cell line RAW 264.7 to LPS increased phosphorylation of the mitogen-activated protein kinase family members ERK1/2, p38 and JNK1/2 in a time-dependent manner. Pretreatment of RAW 264.7 with luteolin inhibited the LPS-induced ERK1/2 and p38, but not JNK1/2, phosphorylation, and blocked the LPS-induced TNF-alpha release. 3: To investigate which of these pathways contribute to the inhibitory effects of luteolin on TNF-alpha release, cells were pretreated with pharmacological inhibitors of these pathways; PD98059 and SB203580 when used alone failed to inhibit TNF-alpha release, whereas pretreatment with both agents attenuated TNF-alpha release. 4: We have previously shown that luteolin blocks Akt phosphorylation in response to LPS in RAW 264.7 macrophages. To determine the role of Akt in TNF-alpha release, cells were transiently transfected with a dominant negative form of Akt (K179M). Overexpression of K179M Akt did not alter LPS-induced TNF-alpha release, suggesting that inhibition of this kinase does not mediate the inhibitory action of luteolin. 5: In addition, DRB (a pharmacological inhibitor of CK2) blocked TNF-alpha release in a concentration-dependent manner, whereas co-treatment of cells with luteolin and DRB did not have an additive effect. 6: We conclude that luteolin interferes with LPS signalling by reducing the activation of several MAPK family members and that its inhibitory action on TNF-alpha release correlates with inhibition of ERK, p38 and CK2 activation.