Induction of cytochromes P-450 1A1 and 1B1 by motorcycle exhaust particulate in human breast cancer MCF-7 cells

The effects of motorcycle exhaust particulate (MEP) on cytochrome P-450-dependent monooxygenases were determined using MCF-7 human breast cancer cells treated with organic extracts of MEP. Treatment with MEP extract produced concentration- and time-dependent increases of monooxygenase activity in S9 fractions. Treatment with 50 microg/ml MEP extract for 24 h increased benzo[a]pyrene hydroxylase and 7-ethoxycoumarin, 7-ethoxyresorufin, and methoxyresorufin O-dealkylases activities in S9. Treatments with 1 and 10 microg/ml MEP extract for 24 h markedly enhanced catabolism of 17beta-estradiol in MCF-7 cells. Cotreatment of the cells with 2 microM alpha-naphthoflavone, a cytochrome P-450 inhibitor and arylhydrocarbon receptor antagonist, blocked the increase of benzo[a]pyrene hydroxylase activity induced by treatment with MEP extract alone. Immunoblot analyses of S9 proteins using a mouse monoclonal antibody 1-12-3 against rat cytochrome P-450 1A1 and a rabbit polyclonal antibody against human cytochrome P-450 1B1 revealed that MEP extract induced proteins immunorelated to cytochromes P-450 1A1 and 1B1. RNA blot analysis of total RNA using human cytochrome P-450 (CYP)1A1 3'-end and human CYP1B1 RT-PCR product cDNA probes showed that MEP extract increased the levels of cytochromes P-450 1A1 and 1B1 mRNA hybridizable to the respective cDNA probes. Treatment with 10 micro M benzo[a]pyrene, a component of MEP extract, for 24 h induced catalytic activity, protein, and mRNA of cytochromes P-450 1A1 and 1B1 in MCF-7 cells. Treatment with MEP extract increased cytochromes P-450 1A1 and 1B1 proteins and mRNA levels in NCI-H322 human lung carcinoma and CL5 human lung adenocarcinoma cells. The extract also increased cytochrome P-450 1A1, but not cytochrome P-450 1B1, protein, and mRNA, in HepG2 human hepatoma cells. The present findings demonstrate that MEP extract has the ability to induce cytochromes P-450 1A1 and 1B1 in the estrogen-responsive MCF-7 cells. Induction of the carcinogen- and estrogen-metabolizing cytochromes P-450 1A1 and 1B1 may be an important factor to consider in assessing the potential health effects associated with human exposure to MEP.     

辛基酚对MCF-7乳腺癌细胞增殖及凋亡作用研究

目的探讨辛基酚（octylphenols,OP）诱导乳腺癌细胞凋亡及抑制乳腺癌细胞增殖的可能机制。方法应用MTT法及流式细胞仪检测OP对乳腺癌细胞MCF-7的增殖抑制及细胞周期的变化;Real Time PCR和Western blot法检测OP对MCF-7乳腺癌细胞中细胞周期相关蛋白p27Kip1和CyclinE的mRNA及蛋白表达的影响及对凋亡抑制蛋白PAK4表达的影响。结果 OP对MCF-7细胞增殖有明显的抑制作用,MCF-7细胞阻滞在G0/G1期,使S期的细胞减少;Real Time PCR和Western Blot检测发现培养的MCF-7细胞,随着OP的处理浓度增加,CyclinE蛋白在分子水平和蛋白水平均降低,p27Kip1的表达量升高。结论 OP可能通过调控细胞周期相关蛋白的表达,抑制MCF-7乳腺癌细胞增殖。     

NADH: Ubiquinone Oxidoreductase Inhibitors Block Induction of Ornithine Decarboxylase Activity in MCF-7 Human Breast Cancer Cells*

Abstract: Rotenone is the classical inhibitor of NADH: ubiquinone oxidoreductase and its analogue deguelin is a potent inhibitor of 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced ornithine decarboxylase mRNA steady state level and enzyme activity in mouse 308 cells (Gerhäuser et al. 1995). In MCF-7 human breast cancer cells, rotenone, deguelin and two structurally-unrelated miticides (pyridaben and fenazaquin) inhibit not only NADH: ubiquinone oxidoreductase but also induced ornithine decarboxylase activity with IC₅₀ values of <1 to 70 nM. Rotenone inhibits ornithine decarboxylase activity equally well as induced by TPA, insulin-like growth factor I and 17β-oestradiol. Pyridaben is the most potent of the four inhibitors not only for NADH: ubiquinone oxidoreductase activity (bovine heart enzyme) and TPA-induced ornithine decarboxylase activity and mRNA steady state level but also for TPA-induced reactive oxygen species. It is therefore proposed that NADH: ubiquinone oxidoreductase inhibitors block multiple and possibly reactive oxygen species-modulated pathways which regulate ornithine decarboxylase activity.     

蛇床子素通过p53信号通路诱导人乳腺癌细胞株MCF-7凋亡

目的 探讨蛇床子素对人乳腺癌细胞株MCF-7的作用及其机制。方法 对数生长期的MCF-7 细胞用0,25,50,100 mmol·L^-1的蛇床子素处理。细胞培养48 h后,利用MTT检测细胞增殖;流式检测细胞凋亡和膜电位。RT-PCR检测p53、p21、BCL-2、Bax和CytC mRNA水平;免疫印迹法检测p53、p21、BCL-2、Bax 和CytC 表达。结果 蛇床子素可以成浓度依赖性诱导MCF-7 细胞增殖抑制和凋亡,上调Bax、p53、p21和CytC表达,下调 Bcl-2的表达以及细胞膜电位。结论 蛇床子素可通过激活p53信号通路而诱导MCF-7细胞凋亡。     

青藤碱逆转人乳腺癌MCF-7细胞他莫昔芬耐药及机制研究

目的 探究青藤碱（sinomenine,SIN）对人乳腺癌MCF-7细胞他莫昔芬（tamoxifen,TAM）耐药的逆转作用及相关机制。方法 采用高剂量短时间刺激诱导法构建MCF-7/TAM耐药株,并通过MTT法验证细胞耐药性的改变,进一步采用MTT法检测SIN和TAM对MCF-7/TAM细胞的增殖抑制作用,并采用CompuSyn软件评估两者的联合效应。流式细胞术检测SIN和TAM对MCF-7/TAM细胞凋亡和周期的影响,Western blotting检测SIN对MCF-7/TAM细胞中PI3K/AKT/mTOR信号通路的影响。结果 MCF-7/TAM细胞对TAM敏感性显著降低,已产生耐药性;SIN和TAM单用均能够抑制MCF-7/TAM细胞的增殖,TAM和SIN联合使用对MCF-7/TAM细胞的抑制作用显著增强,经CompuSyn软件分析显示两药具有协同作用;SIN和TAM联用能够更显著地诱导MCF-7/TAM细胞凋亡和阻滞细胞周期;MCF-7/TAM细胞中PI3K、Akt和mTOR的磷酸化水平显著高于MCF-7细胞,SIN干预后MCF-7/TAM细胞中PI3K、Akt和mTOR的磷酸化水平显著下降。结论 SIN能够通过调控PI3K/AKT/mTOR信号通路,从而逆转MCF-7细胞对TAM耐药。     

PTEN 在乳腺癌对顺铂化疗敏感性中的作用及其机制研究

目的：探讨PTEN在乳腺癌对顺铂化疗敏感性中的作用及其可能的机制。方法应用脂质体转染技术建立PTEN沉默的乳腺癌细胞系MCF-7/PTENi,通过MTT实验检测其对顺铂的敏感性,并通过Western印迹法检测细胞中Bcl-2的表达水平;应用小分子抑制剂ABT-737抑制Bcl-2表达后,再次检测MCF-7/PTENi对顺铂的敏感性。结果 MCF-7/PTENi和阴性对照细胞（MCF-7/NC）对顺铂的IC50值分别为（16.01±3.03）和（7.86±0.85）μM,两者差异有统计学意义（P=0.003）。MCF-7/PTENi细胞中Bcl-2的表达水平明显高于MCF-7/NC细胞（P=0.015）。2μM ABT-737处理的MCF-7/PTENi和MCF-7/NC细胞对顺铂的IC50值比较无显著性差异（P=0.087）。结论PTEN沉默可降低乳腺癌细胞对顺铂的敏感性,其机制可能与其增加Bcl-2的表达有关。     

冬凌草甲素对MCF-7细胞的生长抑制作用及诱导凋亡作用的实验研究

目的探讨冬凌草甲素对人乳腺癌细胞MCF-7细胞的生长抑制作用及诱导凋亡作用。方法以不同浓度的冬凌草甲素作用于体外培养的MCF-7细胞,MTT法检测细胞生长抑制率,应用Hoechst 33258荧光染色法以及流式细胞仪观察细胞凋亡情况。结果冬凌草甲素可显著抑制MCF-7细胞的生长及诱导细胞发生凋亡,并呈现出一定的剂量-效应与时间-效应关系。Hoechst 33258荧光染色观察到典型的核浓缩、核碎裂等细胞凋亡的形态学变化。结论冬凌草甲素能显著抑制MCF-7细胞的生长,诱导细胞发生凋亡是其重要作用方式。     

SMYD3调控人乳腺癌MCF-7细胞增殖机制的研究

目的：通过转染技术抑制或增强SMYD3基因的表达,以探讨SMYD3对乳腺癌MCF-7细胞增殖的调控机制机制。方法：以MTY法和软琼脂克隆形成实验研究抑制或增强SMYD3基因表达对细胞增殖的影响,以RT-PCR法和Western印迹法检测MCF-7细胞经转染后,胞内SMYD3、ERK／MAPK通路相关蛋白及其磷酸化产物,以及凋亡和细胞周期调控相关蛋白表达水平的变化。结果：用针对SMYD3基因的shRNAs表达质粒转染MCF-7细胞后,其SMYD3基因mRNA和蛋白表达水平下调,细胞生长受到抑制,细胞中ERK1／2、CyclinD1和CDK4蛋白水平明显下调;软琼脂克隆形成实验显示,增强SMYD3基因表达能明显促进MCF-7细胞克隆形成。结论：SMYD3可通过激活ERK／MAPK信号转导通路和上调细胞周期相关蛋白CyclinD1和CDK4的水平提高肿瘤细胞的增殖能力。     

消瘤1号诱导MCF-7人乳腺癌细胞凋亡的研究

目的:研究中成药消瘤1号诱导MCF-7人乳腺癌细胞的凋亡作用,并通过分析其作用后MCF-7细胞Bax和Bcl-2蛋白表达的变化,探讨其诱导MCF-7细胞凋亡的分子机制。方法:采用细胞培养技术,用1、10、100、1000μg·mL-1的消瘤1号处理MCF-7细胞24h,PI染细胞,流式细胞仪测定细胞周期的变化,Western Blot法检测Bax和Bcl-2蛋白的表达。结果:流式细胞仪检测结果表明细胞阻滞在G0/G1期;Weston Blot法测定结果表明消瘤1号能够增加细胞中Bax蛋白表达,减少Bcl-2蛋白表达,且该2种蛋白的表达依赖于消瘤1号的浓度。结论:消瘤1号可通过调节Bax/Bcl-2蛋白表达的变化诱导MCF-7细胞凋亡。     

羽扇豆醇通过MAPKs信号通路对人乳腺癌MCF-7细胞增殖的抑制作用研究

目的:探讨羽扇豆醇对人乳腺癌MCF-7细胞增殖的抑制作用及可能机制。方法:以MCF-7细胞为对象,采用MTT法检测不同剂量羽扇豆醇(7.5、15、30、60、90 mg/L)作用24 h后的细胞增殖情况,并计算细胞存活率和半数抑制浓度(IC_(50));采用倒置显微镜和细胞克隆试验分别观察和检测不同剂量羽扇豆醇(15、30、60 mg/L)作用24 h后的细胞形态学特征以及克隆集落形成情况,并计算克隆形成率;分别采用MTT法和Western blotting法检测加用丝裂原活化蛋白激酶(MAPKs)信号通路相关调控蛋白抑制剂(PD98059、SP600125、SB203580)后细胞的增殖情况和相关调控蛋白[细胞外调节蛋白激酶1/2(ERK1/2)、磷酸化ERK1/2(p-ERK1/2)、c-Jun氨基末端激酶(JNK)、磷酸化JNK(p-JNK)、p38丝裂原活化蛋白激酶(p38 MAPK)、磷酸化p38 MAPK(p-p38MAPK)]的表达情况。结果:经15、30、60、90 mg/L羽扇豆醇作用后,细胞的存活率均显著降低(P<0.05或P<0.01);该化合物的IC_(50)值为52.94 mg/L。经15、30、60 mg/L羽扇豆醇作用后,各组细胞形态均有所改变,并可见细胞脱落、漂浮、固缩、变圆、体积变小、坏死等现象,其克隆集落形成均有所减少,克隆形成率均显著降低(P<0.05或P<0.01)。单用羽扇豆醇时,细胞的存活率(60mg/L羽扇豆醇)均较对照组显著降低,p-ERK1/2(15、30、60 mg/L羽扇豆醇)、p-JNK(30、60 mg/L羽扇豆醇)、p-p38 MAPK(30、60mg/L羽扇豆醇)的相对表达量均较对照组显著升高(P<0.05或P<0.01);加用相应抑制剂后,联用组细胞的存活率均较60 mg/L羽扇豆醇组显著升高,p-ERK1/2、p-JNK、p-p38 MAPK的相对表达量均较60 mg/L羽扇豆醇组显著降低(P<0.05或P<0.01)。结论:羽扇豆醇对人乳腺癌MCF-7细胞的增殖具有明显的抑制作用,其机制可能与促进MAPKs信号通路相关调控蛋白的磷酸化有关。     

黄芩素对乳腺癌细胞MCF-7和MDA-MB-231增殖的影响

目的：探讨植物雌激素结构类似物黄芩素对乳腺癌细胞MCF-7和MDA－MB-231增殖的影响。方法：MTT法测定不同剂量黄芩素作用于MCF－7和MDA—MB-231细胞株不同时间后对细胞增殖的影响;流式细胞术（FCM）检测细胞凋亡情况。结果：随黄芩素浓度增加,细胞增殖受到抑制,细胞的生存率逐渐下降;随着黄芩素作用时间的延长,细胞的生存率也逐渐下降。结论：黄芩素能抑制MCF07和MDA—MB-231细胞的增殖,诱导细胞凋亡的发生。     

Transient induction of cytochromes P450 1A1 and 1B1 in MCF-7 human breast cancer cells by indirubin

The aryl hydrocarbon receptor (AhR), when activated by exogenous ligands such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), regulates expression of several phase I and phase II enzymes and is also involved in the regulation of cell proliferation. Several studies suggest that endogenous AhR ligand(s) may exist. One putative endogenous ligand is indirubin, which was recently identified in human urine and bovine serum. We determined the effect of indirubin in MCF-7 breast cancer cells on induction of the activities of cytochromes P450 (CYP) 1A1 and 1B1, as measured by estradiol and ethoxyresorufin metabolism, and on induction of the CYP1A1 and CYP1B1 mRNAs. With 4-hr exposure, the effects of indirubin and TCDD at 10nM on CYP activity were comparable, but the effects of indirubin, unlike those of TCDD, were transitory. Indirubin-induced ethoxyresorufin-O-deethylase activity was maximal by 6-9 hr post-exposure and had disappeared by 24 hr, whereas TCDD-induced activities remained elevated for at least 72 hr. The effects of indirubin on CYP mRNA induction were maximal at 3 hr. Indirubin was metabolized by microsomes containing cDNA-expressed human CYP1A1 or CYP1B1. The potency of indirubin was comparable to that of TCDD in a CYP1B1-promoter-driven luciferase assay, when MCF-7 cells were co-exposed to the AhR ligands together with the CYP inhibitor, ellipticine. Thus, if indirubin is an endogenous AhR ligand, then AhR-mediated signaling by indirubin is likely to be transient and tightly controlled by the ability of indirubin to induce CYP1A1 and CYP1B1, and hence its own metabolism.     

常春藤皂苷元抑制人乳腺癌MCF-7和肺癌A549裸鼠移植瘤生长研究

目的 研究常春藤皂苷元对人乳腺癌MCF-7和肺癌A549裸鼠移植瘤生长的影响.方法 采用BALB/c裸鼠在体抗肿瘤实验来考察常春藤皂苷元对乳腺癌和肺癌肿瘤的在体抑制率.结果 常春藤皂苷元具有在体抗乳腺癌和肺癌肿瘤的确切活性,各给药组小鼠与阴性对照组相比较,其肿瘤的重量均具有显著性差异(P＜0.0l),抑瘤率均在60％以上.结论 常春藤皂苷元具有显著地抑制人乳腺癌MCF-7和肺癌A549裸鼠移植瘤生长的作用.     

Bromelain-Functionalized Multiple-Wall Lipid-Core Nanocapsules: Formulation,Chemical Structure and Antiproliferative Effect Against Human Breast Cancer Cells (MCF-7)

Purpose

This study was conducted a promising approach to surface functionalization developed for lipid-core nanocapsules and the merit to pursue new strategies to treat solid tumors.

Methods

Bromelain-functionalized multiple-wall lipid-core nanocapsules (Bro-MLNC-Zn) were produced by self-assembling following three steps of interfacial reactions. Physicochemical and structural characteristics, in vitro proteolytic activity (casein substrate) and antiproliferative activity (breast cancer cells, MCF-7) were determined.

Results

Bro-MLNC-Zn had z-average diameter of 135 nm and zeta potential of +23 mV. The complex is formed by a Zn-N chemical bond and a chelate with hydroxyl and carboxyl groups. Bromelain complexed at the nanocapsule surface maintained its proteolytic activity and showed anti-proliferative effect against human breast cancer cells (MCF-7) (72.6?±?1.2% at 1.250 μg mL^?1 and 65.5?±?5.5% at 0.625 μg mL^?1). Comparing Bro-MLNC-Zn and bromelain solution, the former needed a dose 160-folds lower than the latter for a similar effect. Tripan blue dye assay corroborated the results.

Conclusions

The surface functionalization approach produced an innovative formulation having a much higher anti-proliferative effect than the bromelain solution, even though both in vitro proteolytic activity were similar, opening up a great opportunity for further studies in nanomedicine.

     

ADAM17-siRNA抑制人MCF-7乳腺癌细胞体外侵袭能力的研究

目的:观察人MCF-7乳腺癌细胞中解聚素-金属蛋白酶17(ADAM17)的表达受抑制后对肿瘤细胞体外侵袭能力的影响。方法:构建可以表达针对ADAM17的小干扰RNA(siRNA)的干涉载体,转染人乳腺癌细胞系MCF-7。利用real-time PCR法检测肿瘤细胞内ADAM17 mRNA的表达水平,Western blot法检测ADAM17蛋白的表达,Transwell方法检测肿瘤细胞的体外侵袭能力。结果:ADAM17 mRNA及蛋白在MCF-7细胞中呈高表达,转染特异性ADAM17-siRNA后,其表达显著被抑制,同时细胞的体外侵袭能力也明显受到抑制。结论:ADAM17及特异性的siRNA有望成为抗肿瘤侵袭治疗的新方法。     

Induction of liver microsomal cytochrome P-450 2B1 by dimethyl diphenyl bicarboxylate in rats.

Dimethyl diphenyl bicarboxylate (dimethyl-4,4'-dimethyloxy-5,6,5',6'-dimethylene-dioxy-di phe nyl-2,2'- bicarboxylate, DDB), a synthetic mimic of the natural product schizandrin C, is used in China as a hepatoprotective agent to improve the liver functions of patients with hepatitis or under cancer chemotherapy. In this study, we investigated the effects of DDB on liver microsomal drug-metabolizing enzymes. When male Sprague-Dawley rats were treated with a daily intragastric dose of DDB (200 mg.kg-1) for 3 d, the microsomal pentoxyresorufin dealkylase activity and P-450 2B1 protein levels were markedly increased. The fold increase was lower than that by phenobarbital (75 mg.kg-1, ip once daily x 3 d). The level of P-450 2B1 mRNA was elevated by DDB but the magnitude of the elevation was much less than that caused by phenobarbital. DDB also increased the rates of testosterone hydroxylation at positions 16 beta, 16 alpha, 6 beta, and 2 beta as well as the rate of ethoxyresorufin dealkylation, suggesting moderate increases in the levels of P-450 3A and P-450 1A1 in addition to the huge increase in P-450 2B1. The level of glutathione S-transferase was also slightly increased, but the levels of P-450 2E1 and NAD(P)H: quinone oxidoreductase were not changed. The results indicate that DDB is an inducer of P-450 2B1.     

Cytochromes P-4501A, P-4503A and P-4502B in liver and heart of Mugil capito treated with CYP1A inducers

Hepatic microsomes of Aroclor 1254-treated Mugil capito showed a single protein band detected in immunoblot with monoclonal antibody 1-12-3 to teleost (scup) CYP1A. The hepatic CYP1A like protein was induced with dose dependency after exposure of the fish to β-naphthoflavone (BNF) as well as to Aroclor 1254. The induced mullet hepatic CYP1A protein was confined to a distinct fraction obtained by DE-52 anion exchange chromatography, and its relative content in that fraction increased in fish that were treated with higher doses of inducer. EROD (7-ethoxyresorufin O-deethylase) activity in hepatic microsomes from mullet treated with various doses of BNF correlated significantly (r(2)=0.81502, P<0.01) with CYP1A content. Treatment of the mullet with low dose of Aroclor 1254 (25 mg/kg) induced only traces of CYP1A in liver microsomes (5.1±4.8 mg/kg). However, in mullet treated with the high dose of Aroclor 1254 (100 mg/kg) there was a dramatic induction in CYP1A content (408±275 pmol/mg) and this hemoprotein comprised about 83% of the total P-450 content of liver microsomes. The total level of P-450, although induced in the liver tissue, was not induced in heart tissue of Aroclor 1254 treated mullet. On the other hand, P-4501A was induced in treated mullet to a level that comprised almost all of the cardiac P-450 content. EROD activity in the heart tissue of induced mullet was characterized by low V(max) and high K(m) values (K(m)=2.35 mM, V(max)=39.5 pmol/min per mg) compared to the values recorded for the enzyme from the liver (K(m)=1.0 mM, V(max)=288.0 pmol/min per mg). Cardiac CYP1A with low catalytic activity and repression of CYP-types other then CYP1A in heart of CYP1A induced fish may be part of a mechanism aimed to preserve crucial levels of electron donors and molecular oxygen in cardiac muscle of fish exposed to CYP1A inducers.     

Selective mechanism-based inactivation of cytochromes P-450 2B1 and P-450 2B6 by a series of xanthates.

Fifteen xanthates with carbon chains of different lengths or substitutions, including the antiviral compound D609 (O-tricyclo[5.2. 1.0(2,6)]dec-9-yl-dithiocarbonate), were tested for their ability to inactivate cytochromes P-450 (P-450s) 2B1 and 2B6. All of the xanthates tested were found to inactivate P-450 2B1 in a time- and concentration-dependent manner. The rates of inactivation at 30 degrees C ranged from 0.22 min-1 to 0.02 min-1. The concentrations required for half-maximal inactivation were between 2.4 and 69 microM. A general trend in the inactivation kinetics could be observed with an increasing chain length of the xanthates. Longer carbon chains resulted in slower rates of inactivation with longer half-times of inactivation and higher partition ratios. For P-450 2B1, the most effective inactivators were xanthates with substitutions of intermediate length. The best inactivator for P-450 2B1 was the C8 xanthate, with an inactivation potency (KI) of 2.4 microM, a rate of inactivation of 0.07 min-1, and a partition ratio of 4. Four xanthates were further examined for their effect on the 7-ethoxy-4-(trifluoromethyl)coumarin activity of P-450 2B6. The C8 xanthate was again the most effective inactivator, with a KI of 1 microM. Although the KI values were generally lower than those found with P-450 2B1, the rates of inactivation for P-450 2B6 with the various xanthates were 3- to 5-fold slower. In addition, the isozyme selectivity of xanthates was tested with P-450s 2E1, 1A1, 3A2, 3A4, 2C9, and 2D6. P-450 2E1 was inactivated by xanthates at concentrations 15- to 100-fold higher than those required to inactivate either P-450 2B1 or 2B6. P-450 1A1 was not inactivated by xanthates. However, all of the xanthates tested were able to inhibit the enzymatic activity of P-450 1A1 to a different extent, depending on the length of the xanthate carbon chain. Virtually no inactivation of P-450s 2D6 or 2C9 was seen, except that C8 and D609 were inhibitory at high concentrations (0.2-0.6 mM). None of the xanthates studied had any effect on the activities of P-450s 3A2 or 3A4.