6‐Dehydrogingerdione,an active constituent of dietary ginger,induces cell cycle arrest and apoptosis through reactive oxygen species/c‐Jun N‐terminal kinase pathways in human breast cancer cells

This study is the first to investigate the anticancer effect of 6‐dehydrogingerdione (DGE), an active constituent of dietary ginger, in human breast cancer MDA‐MB‐231 and MCF‐7 cells. DGE exhibited effective cell growth inhibition by inducing cancer cells to undergo G2/M phase arrest and apoptosis. Blockade of cell cycle was associated with increased levels of p21, and reduced amounts of cyclin B1, cyclin A, Cdc2 and Cdc25C. DGE also enhanced the levels of inactivated phosphorylated Cdc2 and Cdc25C. DGE triggered the mitochondrial apoptotic pathway indicated by a change in Bax/Bcl‐2 ratios, resulting in caspase‐9 activation. We also found the generation of reactive oxygen species is a critical mediator in DGE‐induced cell growth inhibition. DGE clearly increased the activation of apoptosis signal‐regulating kinase 1 and c‐Jun N‐terminal kinase (JNK), but not extracellular signal‐regulated kinase 1/2 (ERK1/2) and p38. In addition, antioxidants vitamin C and catalase significantly decreased DGE‐mediated JNK activation and apoptosis. Moreover, blocking JNK by specific inhibitors suppressed DGE‐triggered mitochondrial apoptotic pathway. Taken together, these findings suggest that a critical role for reactive oxygen species and JNK in DGE‐mediated apoptosis of human breast cancer.     

Acanthoic acid induces cell apoptosis through activation of the p38 MAPK pathway in HL-60 human promyelocytic leukaemia

The present study was designed to evaluate the molecular mechanisms of the action of acanthoic acid (ACAN) from Acanthopanax koreanum (Araliaceae) against HL-60 human promyelocytic leukaemia cells. ACAN reduced the proliferation of HL-60 cells in a dose- and time-dependent manner accompanied by the induction of apoptosis. Possible mechanisms of ACAN-induced apoptosis were also examined. The results showed that ACAN-induced the phosphorylation of members of the mitogen-activated protein kinase (MAPK) family, c-Jun N-terminal kinase (JNK), p38 MAPK (p38), and extracellular signal-regulated kinase (ERK). A specific p38 MAPK inhibitor (SB203580) significantly blocked ACAN-induced apoptosis and cell viability, whereas an ERK inhibitor (PD98059) and JNK inhibitor (SP600125) had no effect. Moreover, ACAN induced the cleavage of caspase-3 and poly-ADP-ribose polymerase (PARP), and decreased the level of Bcl-xL, but these effects were inhibited by SB203580 pre-treatment. These results strongly suggest that ACAN may have cancer chemopreventive and therapeutic potential, due to its ability to activate the p38 MAPK-mediated signalling pathways.     

Phenethyl isothiocyanate inhibits STAT3 activation in prostate cancer cells

This study was undertaken to investigate the mechanism by which phenethyl isothiocyanate (PEITC), a natural compound from cruciferous vegetables, exhibits antitumor effect on prostate cancer cells. Cell proliferation, cell cycle, Western blot, gene transfer, and reporter assays were used to test the effects of PEITC on the growth and IL6/JAK/STAT3 pathway in prostate cancer. The result showed that PEITC significantly inhibited DU145 cell proliferation in a dose‐dependent manner and induced the cell arrest at G2‐M phase. PEITC inhibited both constitutive and IL‐6‐induced STAT3 activity in DU145 cells. IL‐6‐stimulated phosphorylation of JAK2, an STAT3 upstream kinase, was also attenuated by PEITC. Moreover, an antioxidant reagent, N‐acetyl‐L ‐cysteine (NAC) which suppresses reactive oxygen species (ROS) generation, reversed the early inhibitory effects of PEITC on cell proliferation, constitutive or IL‐6‐mediated JAK‐STAT3 phosphorylation in PCa cells. Taken together, our data demonstrated that PEITC can inhibit the activation of the JAK‐STAT3 signal‐cascade in prostate cancer cells and the underlying mechanism may be partially involved with blocking cellular ROS production during the early stage of the signaling activation by IL‐6.     

Cover Picture: Mol. Nutr. Food Res. 9'2010

Regular issues provide a wide range of research and review articles covering all aspects of Molecular Nutrition & Food Research. Selected topics of issue 09 are: Diet‐induced obesity regulates the galanin‐mediated signaling cascade in the adipose tissue of mice 6‐Dehydrogingerdione, an active constituent of dietary ginger, induces cell cycle arrest and apoptosis through reactive oxygen species/c‐Jun N‐terminal kinase pathways in human breast cancer cells Ursolic acid, a naturally occurring triterpenoid, suppresses migration and invasion of human breast cancer cells by modulating c‐Jun N‐terminal kinase, Akt and mammalian target of rapamycin signaling Eupafolin, a flavonoid isolated from Artemisia princeps, induced apoptosis in human cervical adenocarcinoma HeLa cells Isolation, cloning, and characterization of the 2S albumin: A new allergen from hazelnut     

Phenethyl isothiocyanate suppresses nitric oxide production via inhibition of phosphoinositide 3‐kinase/Akt‐induced IFN‐γ secretion in LPS‐activated peritoneal macrophages

Phenethyl isothiocyanate (PEITC), a constituent of many cruciferous vegetables, is well known to have versatile physiological activities, including chemopreventive effects. On the other hand, its anti‐inflammatory effects are poorly reported. Nitric oxide (NO) is associated with a wide variety of inflammatory diseases. In this study, we investigated the effects of PEITC on NO production in LPS‐activated peritoneal macrophages from ICR mice. The signaling pathway of LPS‐induced NO production was examined using neutralizing antibodies [anti‐interferon (IFN)‐γ and anti‐interleukin (IL‐12)] and specific protein kinase inhibitors, as well as others. The activity of PEITC toward NOx production was assessed in mice that received LPS via intraperitoneal administration. The neutralizing antibody of anti‐IFN‐γ, but not anti‐IL‐12, suppressed LPS‐induced NO production by 90%. LY294002, a specific inhibitor of phosphoinositide‐3‐kinase, suppressed Akt and IFN‐γ mRNA expression up‐regulated by LPS, whereas PEITC exhibited a similar inhibition profile. Furthermore, oral administration of PEITC significantly suppressed the serum concentration of NOx in ICR mice. Our results suggest that PEITC suppresses LPS‐induced NO production via inhibition of Akt activation and the resultant decrease in expression of IFN‐γ. This is one of the first reports to demonstrate a marked anti‐inflammatory effect of PEITC following its oral administration.     

Phenethyl isothiocyanate decreases thymic stromal lymphopoietin‐induced inflammatory reactions in mast cells

Phenethyl isothiocyanate (PEITC) has been reported to have anti‐inflammatory and anti‐carcinogenic properties. However, the anti‐inflammatory effects of PEITC on thymic stromal lymphopoietin (TSLP)‐induced inflammatory responses are uncertain. This study evaluates pharmacological activities of PEITC on inflammatory reactions in TSLP‐stimulated mast cells. Human mast cell line HMC‐1 was treated with PEITC (0.04, 0.4, and 4 µM) and subjected to inflammation by TSLP. Our results showed that PEITC significantly attenuated IL‐13 and TNF‐α levels increased by TSLP in HMC‐1. PEITC significantly decreased TSLP‐promoted HMC‐1 proliferation and Ki67 mRNA expression. Protein levels of MDM2 and pSTAT6 increased by TSLP were significantly suppressed by PEITC in HMC‐1. In addition, PEITC significantly enhanced protein levels of cleaved poly ADP‐ribose polymerase and p53 decreased by TSLP. Based on the effects of PEITC on inflammation and proliferation in this study, it is possible that PEITC is a potential candidate to treat mast cells‐mediated inflammatory disorders.

Practical applications

This report provides strong evidence that Phenethyl isothiocyanate (PEITC) which is a dietary constituent derived from cruciferous vegetables, may be considered an alternative agent for treatment of mast cells‐mediated inflammatory disorders.     

Quercetin‐induced apoptotic cascade in cancer cells: Antioxidant versus estrogen receptor α‐dependent mechanisms

The flavonol quercetin, especially abundant in apple, wine, and onions, is reported to have anti‐proliferative effects in many cancer cell lines. Antioxidant or pro‐oxidant activities and kinase inhibition have been proposed as molecular mechanisms for these effects. In addition, an estrogenic activity has been observed but, at the present, it is poorly understood whether this latter activity plays a role in the quercetin‐induced anti‐proliferative effects. Here, we studied the molecular mechanisms of quercetin committed to the generation of an apoptotic cascade in cancer cells devoid or containing transfected estrogen receptor α (ERα; i.e., human cervix epitheloid carcinoma HeLa cells). Although none of tested quercetin concentrations increase reactive oxygen species (ROS) generation in HeLa cells, quercetin stimulation prevents the H₂O₂‐induced ROS production both in the presence and in the absence of ERα. However, this flavonoid induces the activation of p38/MAPK, leading to the pro‐apoptotic caspase‐3 activation and to the poly(ADP‐ribose) polymerase cleavage only in the presence of ERα. Notably, no down‐regulation of survival kinases (i.e., AKT and ERK) was reported. Taken together, these findings suggest that quercetin results in HeLa cell death through an ERα‐dependent mechanism involving caspase‐ and p38 kinase activation. These findings indicate new potential chemopreventive actions of flavonoids on cancer growth.     

Study of the fermentation conditions and the antiproliferative activity of rapeseed peptides by bacterial and enzymatic cooperation

Based on previously determined preparation conditions of rapeseed peptides by mixed solid‐state fermentation, the optimisation of the fermentation conditions of rapeseed meal to obtain rapeseed peptides using the cooperation of mixed bacteria and a neutral protease was studied. The appropriate parameters of synergistic fermentation using mixed bacteria and a neutral protease were as follows: initial fermentation pH of 6.5, fermentation temperature of 35 °C, fermentation time of 2 day and the added amount of neutral protease of 200 U g^?1 weight of dry rapeseed meal. Furthermore, Tricine‐SDS‐PAGE analysis of the rapeseed peptide extracts was performed, and the amino acid composition of the rapeseed meal before and after fermentation was evaluated. Then, the analysis of cytotoxicity and antiproliferative activity of the extracts on human HepG2 liver cancer cells, human MCF‐7 breast cancer cells and human HeLa cervical cancer cells indicated that the extracts had an antiproliferative effect on the cancer cells.     

虾青素保护PC-3细胞免受H2O2氧化应激的作用机制

目的：研究虾青素对过氧化氢诱导PC-3细胞氧化应激的保护作用,探索其信号通路机制。方法：建立H2O2 氧化应激模型,采用不同浓度虾青素预处理PC-3细胞,检测细胞存活率、细胞凋亡、活性氧（reactive oxygen species, ROS）水平、B淋巴细胞瘤-2（B-cell lymphoma-2,Bcl-2）、Bcl-2相关X蛋白（Bcl-2-associated X protein,Bax）、 活化半胱天冬酶-3表达及丝裂原活化蛋白激酶-核因子E2相关基因2-血红素氧合酶1（mitogen-activated protein kinases nuclear factor erythroid-2-related factor 2-heme oxygenase 1,MAPK-Nrf2-HO-1）通路的变化。结果：20 μmol/L虾青 素预处理显著提高H2O2所降低的细胞存活率、降低ROS水平（P＜0.05）,同时通过抑制Bcl-2/Bax比率下降及半胱 天冬酶-3的激活,从而使细胞凋亡率从51.4%降低至14.8%,进一步研究发现虾青素能够促进Nrf2磷酸化,并促进 HO-1的表达,呈现浓度依赖性。通过细胞外调节蛋白激酶（extracellular regulated protein kinases,ERK）抑制剂 （U0126）和Akt抑制剂（LY294002）预处理,发现当ERK和磷脂酰肌醇激酶/蛋白激酶B（phosphoinositide 3-kinase/ protein kinase B,PI3K/Akt）通路被抑制后,Nrf2表达降低,表明HO-1上调受上游ERK和胞内PI3K/Akt通路的调 控。在对MAPK途径对细胞毒性影响的研究中,ERK通路被抑制后细胞存活率显著下降,而c-Jun氨基末端激酶 （c-Jun N-terminal kinase,JNK）和p38 MAPK通路被抑制后并不影响其保护作用,表明虾青素抑制细胞存活率下降 是通过MAPK途径中的ERK通路,而不是JNK和p38通路。结论：虾青素预处理PC-3细胞可以减轻H2O2诱导的氧化 应激,维持细胞生理活性。     

Suppression of EGF-induced tumor cell migration and matrix metalloproteinase-9 expression by capsaicin via the inhibition of EGFR-mediated FAK/Akt, PKC/Raf/ERK, p38 MAPK, and AP-1 signaling

Scope: Capsaicin is a cancer‐suppressing agent. The aim of our study was to determine the effect of capsaicin on tumor invasion and migration; the possible mechanisms involved in this inhibition were investigated in human fibrosarcoma cells. Methods and results: We employed invasion, migration and gelatin zymography assays to characterize the effect of capsaicin on HT‐1080 cells. Transient transfection assays and immunoblot analysis were performed to study its molecular mechanisms of action. Capsaicin inhibited the epidermal growth factor (EGF)‐induced activation of matrix metalloproteinase (MMP)‐9 and MMP‐2, and further inhibited cell invasion and migration. Capsaicin decreased the EGF‐induced expression of MMP‐9, MMP‐2, and MT1‐MMP, but did not alter TIMP‐1 and TIMP‐2 levels. Capsaicin suppressed EGF‐induced c‐Jun and c‐Fos nuclear translocation, and also abrogated the EGF‐induced phosphorylation of EGF receptor (EGFR), focal adhesion kinase (FAK), protein kinase C (PKC), phosphatidylinositol 3‐Kinase (PI3K)/Akt, extracellular regulated kinase (ERK)1/2, and JNK1/2, an upstream modulator of AP‐1. Furthermore, the EGFR inhibitor inhibited EGF‐induced MMP‐9 expression, as well as AP‐1 activity and cell migration. Conclusion: Capsaicin inhibited the EGF‐induced invasion and migration of human fibrosarcoma cells via EGFR‐dependent FAK/Akt, PKC/Raf/ERK, p38 mitogen‐activated protein kinase (MAPK), and AP‐1 signaling, leading to the down‐regulation of MMP‐9 expression. These results indicate the role of capsaicin as a potent anti‐metastatic agent, which can markedly inhibit the metastatic and invasive capacity of fibrosarcoma cells.     

Anti-inflammatory effect of phenethyl isothiocyanate, an active ingredient of Raphanus sativus Linne

Phenethyl isothiocyanate (PEITC) is an active ingredient of Raphanus sativus Linne (Cruciferae). However, regulatory mechanism of PEITC involved in caspase-1 signalling has not been fully elucidated in mast cells. First, PEITC inhibited the production of IL-6 through the inhibition of caspase-1/receptor-interacting protein 2, followed by regulation of NF-κB/IκBα pathway or p38 and extracellular signal-regulated kinase mitogen-activated protein kinases. Second, PEITC inhibited the IL-1β production through the inhibition of caspase-1 proteolytic activity. Overall, these results provide a proof that PEITC can inhibit the inflammatory reactions by two distinct pathways in mast cells and open new perspectives to pharmacologically manipulate the expression and production of IL-6 and IL-1β by molecules acting on the caspase-1 pathway.     

Shallot and licorice constituent isoliquiritigenin arrests cell cycle progression and induces apoptosis through the induction of ATM/p53 and initiation of the mitochondrial system in human cervical carcinoma HeLa cells

This study is the first to investigate the anticancer effect of isoliquiritigenin (ISL) in human cervical carcinoma HeLa cells. The results reveal that ISL inhibits HeLa cells by blocking cell cycle progression in the G2/M phase and inducing apoptosis. Blockade of cell cycle is associated with increased activation of ataxia telangiectasia‐mutated (ATM). Activation of ATM by ISL phosphorylated p53 at Serine15, resulting in increased stability of p53 by decreasing p53 and murine double minute‐2 (MDM2) interaction. In addition, ISL‐mediated G2/M phase arrest was also associated with decreases in the amounts of cyclin B, cyclin A, cdc2, and cdc25C, and increases in the phosphorylation of Chk2, cdc25C, and cdc2. The specific ATM inhibitor caffeine significantly decreased ISL‐mediated G2/M arrest by inhibiting the phosphorylation of p53 (Serine15) and Chk2. ISL induced apoptotic cell death is associated with changes in the expression of Bax and Bak, decreasing levels of Bcl‐2 and Bcl‐X_L, and subsequently triggering mitochondrial apoptotic pathway. In addition, pretreatment of cells with caspase‐9 inhibitor blocked ISL‐induced apoptosis, indicating that caspase‐9 activation is involved in ISL‐mediated HeLa cell apoptosis. These findings suggest that ISL may be a promising chemopreventive agent against human uterine cervical cancer.     

Phenethyl isothiocyanate inhibits hypoxia-induced accumulation of HIF-1α and VEGF expression in human glioma cells

Phenethyl isothiocyanate (PEITC), a natural dietary isothiocyanate, inhibits angiogenesis but the molecular mechanisms that underlie this effect are not known. In this study, under hypoxic conditions (1% O₂), we examined the effect of PEITC on the intracellular level of the hypoxia inducible factor (HIF-1α) and extracellular level of the vascular endothelial growth factor (VEGF) in a variety of human cancer cell lines. Surprisingly, we observed that PEITC suppressed the HIF-1α accumulation during hypoxia in human glioma U87, human prostate cancer DU145, colon cancer HCT116, liver cancer HepG2, and breast cancer SkBr3 cells. PEITC treatment also significantly reduced the hypoxia-induced secretion of VEGF. Suppression of HIF-1α accumulation during treatment with PEITC in hypoxia was related to PI3K and MAPK pathways. Taken together, these results suggest that PEITC inhibits the HIF-1α expression through inhibiting the PI3K and MAPK signalling pathway and provide a new insight into a potential mechanism of the anticancer properties of PEITC.     

草苁蓉提取物对HepG2细胞氧化应激损伤的保护作用

目的：研究草苁蓉乙醇提取物（Boschniakia rossica ethanol extract,BREE）对H2O2诱导的HepG2细胞氧化应激损伤的保护作用。方法：用H2O2诱导HepG2细胞氧化应激损伤,采用噻唑蓝（methylthiazolyldiphenyltetrazoliumbromide,MTT）比色法检测BREE对HepG2细胞氧化损伤的保护作用;比色法测定培养液中乳酸脱氢酶（lactate dehydrogenase,LDH）、谷丙转氨酶（alanine aminotransferase,ALT）、谷草转氨酶（aspartateaminotransferase,AST）的释放率,以及细胞中超氧化物歧化酶（superoxide dismutase,SOD）、还原型谷胱甘肽（reduced glutathione,GSH）及丙二醛（malondialdelyde,MDA）水平;蛋白印迹法测定细胞外信号调节蛋白激酶（extracellular signal-regulated kinase,ERK）、c-Jun氨基末端激酶（c-Jun N-terminal kinase,JNK）、p38丝裂原活化蛋白激酶（p38 mitogen-activated protein kinase,p38 MAPK）总蛋白及其磷酸化形式的表达水平以及核转录因子-κB（nuclear factor-κB,NF-κB）的核内转移。结果：BREE单独处理时,在所测质量浓度范围内对HepG2细胞增殖无显著影响。与模型组相比,BREE能显著提高氧化损伤细胞的存活率;降低氧化损伤细胞培养液中LDH、ALT和AST的释放;降低细胞MDA水平,增高细胞SOD活性和GSH含量。氧化损伤发生的不同时期,ERK、JNK、p38 MAPK和NF-κB蛋白均有激活,而BREE在氧化损伤发生1 h时减少ERK激活和NF-κB核转移,氧化损伤发生12 h时减少JNK蛋白激活。结论：BREE对H2O2所致HepG2细胞氧化应激损伤具有保护作用,此作用可能与其抑制ERK、JNK的活化和NF-κB的核内转移有关。     

N-乙酰-半胱氨酸干预壬基酚对小鼠Sertoli TM4细胞的损伤作用

目的：研究N-乙酰-半胱氨酸（N-acetyl-cysteine,NAC）对壬基酚（nonylphenol,NP）诱导的小鼠Sertoli TM4细胞氧化损伤及凋亡的干预作用。方法：以Sertoli TM4细胞为对象,实验分为对照组、NP组（20 μmol/L NP处理）、NP＋NAC组（5 mmol/L NAC预处理4 h后20 μmol/L NP处理24 h）、NAC组（5 mmol/L NAC处理4 h后换正常培养基培养）,采用噻唑蓝法检测细胞存活率;流式细胞术检测活性氧（reactive oxygen species,ROS）含量和细胞凋亡情况;试剂盒法检测超氧化物歧化酶（superoxide dismutase,SOD）活力、过氧化氢酶（catalase,CAT）活力、丙二醛（malondialdehyde,MDA）含量及Caspase-3相对活力;Western blot法检测细胞外信号调节激酶（extracellular signal-regulated kinase,ERK）和c-Jun氨基末端激酶（c-Jun N-terminal kinase,JNK）磷酸化情况。结果：与对照组相比,20 μmol/L NP处理24 h能显著降低细胞存活率（P＜0.05）,同时诱导细胞内ROS生成,下调SOD和CAT活力,增加MDA含量,诱导Sertoli TM4细胞凋亡,增加Caspase-3相对活力,促进ERK、JNK蛋白磷酸化激活;与NP组相比,NAC预处理能够明显削弱NP引起的细胞内ROS生成,使SOD、CAT活力下调,MDA含量增加,Sertoli TM4细胞凋亡,Caspase-3相对活力增强,激活ERK、JNK信号通路。结论：NAC具有干预NP对小鼠Sertoli TM4细胞损伤的作用,这可能与NAC抑制NP诱导的细胞氧化应激和凋亡以及阻断ERK、JNK信号通路的激活相关。     

Nutritional Sources and Anticancer Potential of Phenethyl Isothiocyanate: Molecular Mechanisms and Therapeutic Insights

Phenethyl isothiocyanate (PEITC), a compound derived from cruciferous vegetables, has garnered attention for its anticancer properties. This review synthesizes existing research on PEITC, focusing on its mechanisms of action in combatting cancer. PEITC has been found to be effective against various cancer types, such as breast, prostate, lung, colon, and pancreatic cancers. Its anticancer activities are mediated through several mechanisms, including the induction of apoptosis (programmed cell death), inhibition of cell proliferation, suppression of angiogenesis (formation of new blood vessels that feed tumors), and reduction of metastasis (spread of cancer cells to new areas). PEITC targets crucial cellular signaling pathways involved in cancer progression, notably the Nuclear Factor kappa-light-chain-enhancer of activated B cells (NF-κB), Protein Kinase B (Akt), and Mitogen-Activated Protein Kinase (MAPK) pathways. These findings suggest PEITC's potential as a therapeutic agent against cancer. However, further research is necessary to determine the optimal dosage, understand its bioavailability, and assess potential side effects. This will be crucial for developing PEITC-based treatments that are both effective and safe for clinical use in cancer therapy.     

Effect of orally administered phenethyl isothiocyanate on hepatic gene expression in rats

Scope: Phenethyl isothiocyanate (PEITC) is a constituent of cruciferous vegetables that has demonstrated cancer preventive activity in a number of cancer models including lung, prostate, and breast cancer. Our objective was to examine the effects of the oral administration of PEITC for 7 days on the hepatic expression of genes important in drug metabolism and toxicity in Sprague Dawley rats. The liver is the major site for the metabolism of various xenobiotics and carcinogens, and determining the effects of PEITC on the gene expression of hepatic enzymes may provide insight into mechanisms underlying the cancer preventive activity of PEITC. Methods and results: Using a microarray containing 282 genes, we observed that PEITC significantly up‐regulated UDP‐glucuronosyltransferase UGT1A6 and strongly down‐regulated nicotinamide N‐methyltransferase (NNMT). We also confirmed the down‐regulation of NNMT by real‐time quantitative RT‐PCR. Other genes that were significantly up‐regulated were the drug metabolizing enzyme cyp2b15, the anti‐apoptotic gene bcl2l2, and the stress regulators Gadd45b, Dnajb9, Dnajb5 and Hspb1. Conclusion: Our results indicate new targets that may be important in the mechanisms of the anticancer effects of PEITC. Of particular significance was the down‐regulation of NNMT which may represent a new target for the treatment of a variety of cancers.     

Docosahexaenoic acid downregulates phenobarbital-induced cytochrome P450 2B1 gene expression in rat primary hepatocytes via the c-Jun NH2-terminal kinase mitogen-activated protein kinase pathway

Mitogen-activated protein kinase (MAPK) pathways play central roles in the transduction of extracellular stimuli into cells and the regulation of expression of numerous genes. Docosahexaenoic acid (DHA) was shown to be involved in the regulation of expression of drug metabolizing enzymes (DMEs) in rat primary hepatocytes in response to xenobiotics. Cytochrome P450 2B1 (CYP 2B1) is a DME that is dramatically induced by phenobarbital-type inducers. The constitutive androstane receptor (CAR) plays a critical role in regulating the expression of DMEs, and the phosphorylation/dephosphorylation of CAR is an important event in CYP 2B1 expression. In the present study, we determined the effect of DHA on MAPK transactivation and its role in CYP 2B1 expression induced by phenobarbital. c-Jun NH2-terminal kinase (JNK) JNK1/2 and ERK1/2 were activated by phenobarbital in a dose-dependent manner. DHA (100 muM) inhibited JNK1/2 and ERK2 activation induced by phenobarbital in a time-dependent manner. Both SP600125 (a JNK inhibitor) and SB203580 (a p38 MAPK inhibitor) inhibited CYP 2B1 protein and mRNA expression induced by phenobarbital. SB203580 significantly increased the intracellular 3'-5'-cyclic adenosine monophosphate (cAMP) concentration compared with a control group (p < 0.05). Our results suggest that inhibition of JNK activation by DHA is at least part of the mechanisms of DHA's downregulation of CYP 2B1 expression induced by phenobarbital.     

嗜酸乳杆菌胞外蛋白调控MAPK和PI3K-AKT信号途径关键蛋白活化水平

探讨并揭示嗜酸乳杆菌(Lactobacillus acidophilus)CICC6005分泌的相关蛋白质促进肠道健康及分子机制具有重要研究价值。本实验在确定了L.acidophilus CICC6005分泌的胞外蛋白抑制HT-29结肠癌细胞增殖的基础上,进一步探讨67 ku和37 ku的胞外蛋白通过何种途径发挥抑制结肠癌细胞增殖。研究以HT-29细胞作为靶细胞,用丝裂原激活的蛋白激酶(mitogen activated protein kinase,MAPK)和磷脂酰肌醇-3激酶-丝氨酸/苏氨酸蛋白激酶(phosphatidylinositol 3-kinase-protein kinase B,PI3K-AKT)信号通路为考察对象,以Western Blotting为手段,分析两个通路中关键的靶点蛋白p38、c-Jun氨基末端激酶(c-Jun N-terminal kinase,JNK)、胞外信号调节激酶(extracellular signal-regulated kinase,ERK)、磷酸化p38(phosphorylated p38,p-p38)、磷酸化c-Jun氨基末端激酶(phosphorylated c-Jun N-terminal kinase,p-JNK)、磷酸化的细胞外信号调节蛋白激酶(phosphorylated extracellular signal-regulated kinase,p-ERK)、磷酸化蛋白激酶B(phosphorylated AKT,p-AKT)、PI3K的表达水平,以探讨并阐述源于L.acidophilus CICC6005胞外蛋白调控结肠癌细胞增殖状况的分子机制。结果表明,不同质量浓度的67 ku和37 ku胞外蛋白分别作用HT-29细胞一定时间后,两种胞外蛋白均具有下调两个信号通路途径中p-ERK1/2、p-p38、p-AKT、PI3K蛋白的表达,且存在浓度依赖关系;但对p-JNK、ERK1/2、p38、JNK蛋白的表达没有影响。因此,源于L.acidophilus CICC6005分泌的37 ku和67 ku胞外蛋白表现出显著的抑制HT-29细胞增殖的功能,其机制可能与调控MAPK和PI3K-AKT两个信号通路中几个关键的靶点蛋白的活化水平相关。该研究结果提示,食用嗜酸乳杆菌其分泌的胞外蛋白质将达到维护肠道健康的目标。