用MCF-7细胞检测有机磷农药拟雌激素样活性

目的 观察常用有机磷农药对MCF-7细胞增殖以及对雌激素受体基因和pS2基因表达的影响。方法 选用乐果、乙酰甲胺磷、久效磷、马拉硫磷、对硫磷、对氧磷6种有机磷农药进行MCF-7人乳腺癌细胞增殖实验和转录活化实验。结果 6种有机磷农药不能诱导MCF-7人乳腺癌细胞增殖,但乐果却能使pS2基因表达上调。结论 乐果可能具有拟雌激素样活性,且引起pS2基因表达上调不通过雌激素受体介导。     

甲基硒酸对乳腺癌细胞增殖及生长影响的研究

目的 观察甲基硒酸对乳腺癌细胞系MCF-7体外增殖及生长的影响.方法 以不同浓度的甲基硒酸作用于乳腺癌细胞系MCF-7,在不同时间内观察不同浓度甲基硒酸对乳腺癌细胞体外增殖、形态、生长的影响.采用噻唑盐法测定细胞的增殖,用光学显微镜观察细胞形态及生长情况.结果 ①甲基硒酸可明显抑制乳腺癌细胞的体外增殖.随着药物浓度的增加,甲基硒酸对乳腺癌细胞体外增殖的抑制作用逐渐增强;随着药物作用时间的增加,甲基硒酸对乳腺癌细胞体外增殖的抑制作用也逐渐增强,但作用48小时后,甲基硒酸的作用不再增强;②甲基硒酸可抑制乳腺癌细胞的生长,使乳腺癌细胞发生核碎裂和核消失现象,随着药物浓度及作用时间的增加,对乳腺癌生长及形态改变的作用也逐渐增强.结论 甲基硒酸可抑制乳腺癌细胞的体外增殖、生长,改变乳腺癌细胞形态,甲基硒酸有望成为预防和治疗乳腺癌的一种新方法.     

硒-甲基硒代半胱氨酸诱导乳腺癌细胞凋亡作用

目的 探讨硒-甲基硒代半胱氨酸（MSC）对人乳腺癌MDA-MB-231细胞的生长抑制作用。方法 不同浓度MSC培养液（12.5、25.0、50.0、100.0、200.0 μmol/L）作用于MDA-MB-231细胞24、48 h,噻唑蓝法检测MSC对细胞增殖的抑制作用;Hoechst染色法观察细胞凋亡形态;试剂盒检测超氧化物歧化酶（SOD）、丙二醛（MDA）、谷胱甘肽过氧化物酶（GSH-Px）活力变化。结果 MSC对细胞增殖具有抑制作用,与对照组比较（100±0.00%）,200 μmol/L MSC处理24、48 h细胞生存率[分别为（64.15±2.81）%、（42.57±2.25）%]明显下降（P<0.01）,呈剂量和时间效应关系;Hoechst染色结果显示,高剂量MSC组细胞可见明显染色质凝聚现象;与对照组[SOD （82.47±1.99）、GSH-Px （46.69±0.55） U/mgprot、MDA （5.80±0.11）μmol/mgprot]比较, 200 μmol/L MSC处理组细胞24 h时,细胞内SOD、GSH-Px活力[分别为（20.99±3.03）、（22.00±0.75） U/mgprot]明显下降,MDA含量[（36.20±0.25）μmol/mgprot]明显升高,差异有统计学意义（P<0.01）;相同剂量MSC作用MDA-MB-231细胞48 h时,细胞内氧化应激指标变化趋势与作用24 h时趋势相同。结论 MSC能够抑制乳腺癌细胞MDA-MB-231的增殖,诱导其凋亡,其机制可能与细胞内氧化应激状态改变有关。     

Hydroxytyrosol protects against oxidative DNA damage in human breast cells

Over recent years, several studies have related olive oil ingestion to a low incidence of several diseases, including breast cancer. Hydroxytyrosol and tyrosol are two of the major phenols present in virgin olive oils. Despite the fact that they have been linked to cancer prevention, there is no evidence that clarifies their effect in human breast tumor and non-tumor cells. In the present work, we present hydroxytyrosol and tyrosol's effects in human breast cell lines. Our results show that hydroxytyrosol acts as a more efficient free radical scavenger than tyrosol, but both fail to affect cell proliferation rates, cell cycle profile or cell apoptosis in human mammary epithelial cells (MCF10A) or breast cancer cells (MDA-MB-231 and MCF7). We found that hydroxytyrosol decreases the intracellular reactive oxygen species (ROS) level in MCF10A cells but not in MCF7 or MDA-MB-231 cells while very high amounts of tyrosol is needed to decrease the ROS level in MCF10A cells. Interestingly, hydroxytyrosol prevents oxidative DNA damage in the three breast cell lines. Therefore, our data suggest that simple phenol hydroxytyrosol could contribute to a lower incidence of breast cancer in populations that consume virgin olive oil due to its antioxidant activity and its protection against oxidative DNA damage in mammary cells.     

染料木黄酮对人乳腺癌细胞雌激素样作用机制研究

目的 探讨染料木黄酮(genistein,GEN)对人乳腺癌细胞增殖影响及作用机制.方法 MTT法测定GEN对雌激素依赖性乳腺癌细胞MCF-7和非雌激素依赖性乳腺癌细胞MDA-MB231增殖作用,应用雌激素受体拮抗剂IC1182780观察GEN的雌激素样作用途径,采用流式细胞术分析乳腺癌细胞周期情况.结果 GEN可促进MCF-7细胞的增殖,使G1期向S期转变,增殖作用可被雌激素受体拮抗剂所拮抗;对非雌激素依赖性MDA-MB231细胞增殖无影响.结论 GEN通过雌激素受体(ER)介导而发挥雌激素样活性作用.     

Phytoestrogen consumption and breast cancer risk in a multiethnic population: the Bay Area Breast Cancer Study

Research on the relation between phytoestrogens and breast cancer risk has been limited in scope. Most epidemiologic studies have involved Asian women and have examined the effects of traditional soy foods (e.g., tofu), soy protein, or urinary excretion of phytoestrogens. The present study extends this research by examining the effects of a spectrum of phytoestrogenic compounds on breast cancer risk in non-Asian US women. African-American, Latina, and White women aged 35-79 years, who were diagnosed with breast cancer between 1995 and 1998, were compared with women selected from the general population via random digit dialing. Interviews were conducted with 1,326 cases and 1,657 controls. Usual intake of specific phytoestrogenic compounds was assessed via a food frequency questionnaire and a newly developed nutrient database. Phytoestrogen intake was not associated with breast cancer risk (odds ratio = 1.0, 95% confidence interval: 0.80, 1.3 for the highest vs. lowest quartile). Results were similar for pre- and postmenopausal women, for women in each ethnic group, and for all seven phytoestrogenic compounds studied. Phytoestrogens appear to have little effect on breast cancer risk at the levels commonly consumed by non-Asian US women: an average intake equivalent to less than one serving of tofu per week.     

Conjugated linoleic acid blocks estrogen signaling in human breast cancer cells

Conjugated linoleic acid (CLA), a mixture of positional and geometric isomers of linoleic acid found in dairy products and meat from ruminants, has been widely shown to possess anticarcinogenic activity against breast cancer both in vitro and in animal models. However, little information is available concerning the mechanisms of the antitumor effects of these compounds. In this study, we investigated whether CLA has direct antiestrogenic activity in estrogen receptor positive (ER+) breast cancer cells. Treatment of the ER+ cell line, MCF-7, with 5 purified CLA isomers as well as "mixed" CLA showed a dose-dependent growth inhibition with the 9cis,11cis and 9cis,11trans being the most and least potent isomers, respectively. In assessing effects on a number of variables that play obligatory roles in the estrogen signaling pathway, we determined that CLA treatment downregulated ERalpha expression at both mRNA and protein levels and decreased binding activity of nuclear protein to a canonical estrogen response element (ERE(v)). Using a reporter gene construct (ERE(v)-tk-Luc) that was transiently transfected into MCF-7 cells, we also demonstrated inhibition of promoter activity by CLA that was directly mediated by blockage of activity through the ERE. The results indicated that the order of potency of the CLA isomers for inhibiting activation of ERE(v) was similar to that demonstrated for their antiproliferative activity on MCF-7 cells. Taken together, these findings demonstrate that CLA compounds possess potent antiestrogenic properties that may at least partly account for their antitumor activity on breast cancer cells.     

环境雌激素致乳腺癌细胞DNA损伤作用

目的观察环境雌激素辛基酚（0P）和三羟异黄酮（GEN）对乳腺癌细胞株（MDA-MB-231）增殖和DNA损伤的影响。方法以2，8和32μmol／LOP或GEN与乳腺癌细胞共培养24，48或72h，用四甲基偶氮噻唑蓝（MTT）试验和单细胞凝胶电泳观察环境雌激素影响细胞增殖和DNA损伤程度。结果OP能明显抑制细胞增殖，DNA损伤明显增加，并呈剂量-效应和时间-效应关系。2，8μmol／LGEN促进细胞的增殖，DNA损伤无明显改变，32μmol／L却明显抑制细胞的增殖，彗星拖尾长度明显增长，但增长效应不及OP。结论OP和高浓度GEN通过损伤MDA-MB-231细胞DNA导致细胞增殖受到抑制，但GEN损伤效应不及OP。     

Anticancer activities of pomegranate extracts and genistein in human breast cancer cells

Previous studies have demonstrated the anticarcinogenic activity of pomegranate extracts and genistein in a series of human cancer cells. In the present study, the potential anticancer effects of pomegranate extracts and genistein on inhibition of cell proliferation and induction of apoptosis in human breast cancer cells was investigated. Human breast cancer cells (MCF-7) were cultured as monolayers in complete RPMI 1640 medium. The cells were cultured for 48 hours to allow growth and achieve about 80% confluence in 48-well culture plates, and then exposed to the agents for 24 hours in single and combination treatments. Post-treatment growth rate and apoptosis induction were assessed by the use of a series of bioassays-lactate dehydrogenase and 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (inner salt) for viability and cytotoxicity; acridine orange-ethidium bromide and terminal deoxyribonucleotidyl transferase-mediated dUTP nick-end labeling assays for induction of apoptosis. Both pomegranate extracts and genistein had significant (dose- and time-dependent) cytotoxic and growth inhibition effects on MCF-7 cancer cells. Both growth inhibition and cytotoxicity were significantly higher (P < .01) in the combination treatments than in the single treatments with either agent. The data revealed that both drugs in single and in combination treatments induced apoptosis in MCF-7 cells. Apoptotic induction in the combination treatments was significantly higher (P < .01) than in single treatments. Both pomegranate extracts and genistein inhibit the growth of MCF-7 breast cancer cells through induction of apoptosis, with combination treatment being more efficacious than single treatments.     

Induction of apoptosis in human breast cancer cells by tocopherols and tocotrienols

The apoptosis-inducing properties of RRR-alpha-, beta-, gamma-, and delta-tocopherols, alpha-, gamma-, and delta-tocotrienols, RRR-alpha-tocopheryl acetate (vitamin E acetate), and RRR-alpha-tocopheryl succinate (vitamin E succinate) were investigated in estrogen-responsive MCF7 and estrogen-nonresponsive MDA-MB-435 human breast cancer cell lines in culture. Apoptosis was characterized by two criteria: 1) morphology of 4,6-diamidino-2-phenylindole-stained cells and oligonucleosomal DNA laddering. Vitamin E succinate, a known inducer of apoptosis in several cell lines, including human breast cancer cells, served as a positive control. The estrogen-responsive MCF7 cells were more susceptible than the estrogen-nonresponsive MDA-MB-435 cells, with concentrations for half-maximal response for tocotrienols (alpha, gamma, and delta) and RRR-delta-tocopherol of 14, 15, 7, and 97 micrograms/ml, respectively. The tocotrienols (alpha, gamma, and delta) and RRR-delta-tocopherol induced MDA-MB-435 cells to undergo apoptosis, with concentrations for half-maximal response of 176, 28, 13, and 145 micrograms/ml, respectively. With the exception of RRR-delta-tocopherol, the tocopherols (alpha, beta, and gamma) and the acetate derivative of RRR-alpha-tocopherol (RRR-alpha-tocopheryl acetate) were ineffective in induction of apoptosis in both cell lines when tested within the range of their solubility, i.e., 10-200 micrograms/ml. In summary, these studies demonstrate that naturally occurring tocotrienols and RRR-delta-tocopherol are effective apoptotic inducers for human breast cancer cells.     

New thiophene analogues of kenpaullone: synthesis and biological evaluation in breast cancer cells

Thieno analogues of kenpaullone have been synthesized using an established method. We investigated the effect of five structural analogues of kenpaullone on vincristine sensitive and resistant MCF7 (human mammary adenocarcinoma) cells. One analogue, 8-Bromo-6,11-dihydro-thieno-[3',2':2,3]azepino[4,5-b]indol-5(4H)-one (3a), showed an antiproliferative activity in the drug sensitive cell line that led to cell accumulation in G2/M phase. In addition, repression of cdk1, a G2/M transition key regulator, as well as induction of p21 were observed at the mRNA level. Programmed cell death (apoptosis) was induced in early time treatments and was accompanied by p53 mRNA induction. The antiproliferative and proapoptotic properties of 3a make this CDK inhibitor an interesting candidate for further investigations.     

Effects of arsenic on DNA synthesis in human lymphocytes

Effects of arsenic on DNA synthesis in human lymphocytes were biphasic: Either trivalent (arsenic trioxide and sodium arsenite) or pentavalent (sodium arsenate) arsenic compounds at very low concentrations enhanced DNA synthesis in human lymphocytes stimulated by phytohemagglutinin (PHA), whereas higher concentrations inhibited DNA synthesis. There were differences among individual susceptibities to arsenic-induced DNA synthesis. Either stimulating or inhibiting effects of trivalent arsenic on DNA synthesis in PHA-stimulated lymphocytes were always stronger than those of pentavalent arsenic. Both trivalent and pentavalent arsenic could be rapidly taken up into the human lymphocytes and immediately stimulate or inhibit DNA synthesis. A possible dual effect of arsenic at very low concentrations as both comutagen and inhibitor of mutagenesis is discussed.     

甲基硒酸对乳腺癌细胞体外凋亡和细胞周期的影响

目的:观察甲基硒酸(MSA)对乳腺癌细胞系MCF-7凋亡和细胞周期的影响。方法:以不同浓度的MSA作用乳腺癌细胞系MCF-7,在不同时间内,观察不同浓度MSA对乳腺癌细胞凋亡率和细胞周期的影响。流式细胞术检测细胞凋亡率和细胞周期。结果:①MSA可诱导乳腺癌细胞体外凋亡,随着药物浓度及作用时间的增加,乳腺癌细胞凋亡率逐渐增加。②MSA可改变乳腺癌的细胞周期,将乳腺癌细胞周期阻断在G1期,并且减少S期细胞的比例。结论:MSA可诱导乳腺癌细胞体外凋亡、调控乳腺癌细胞周期。MSA有望成为预防和治疗乳腺癌的一种新方法。     

不同的游离脂肪酸对人乳腺癌细胞凋亡和侵袭的影响

目的探讨不同游离脂肪酸(FFAs)对MDA-MB-231人乳腺癌细胞凋亡和迁移的影响.方法用50、200、500 umol/L三种不同浓度的油酸(0A)和棕榈酸(PA)分别刺激MDA-MB-231细胞,采用实时定量PCR分析细胞中PTEN的mRNA含量,蛋白免疫印迹法检测PTEN和Bcl-2的蛋白表达,原位末端标记法(TUNEL)观察细胞的凋亡情况,小室迁移实验测定细胞的迁移能力.结果OA使MDA-MB-231细胞中PTEN的mRNA和蛋白表达水平降低,Bcl-2蛋白表达升高(P均＜0.05);PA则使PTEN的mRNA和蛋白表达水平上升,Bcl-2蛋白表达下降(P均＜0.05).显微镜下观察到PA刺激后的MDA-MB-231细胞凋亡增加.迁移实验显示OA和PA都能使乳腺癌细胞侵袭能力增强.结论PA可能通过上调PTEN的表达促进MDA-MB-231人乳腺癌细胞凋亡,但同时也增强细胞的侵袭能力.OA也可增强癌细胞侵袭能力.     

Phytosterols reduce in vitro metastatic ability of MDA-MB-231 human breast cancer cells

Metastasis plays a major role in morbidity and mortality from breast cancer. Differences in the incidence and mortality of breast cancer between societies suggest that environmental factors such as diet may play a role in the disease. Previous work from this laboratory suggests that dietary phytosterols (PS) may offer protection from breast cancer by inhibiting growth of the tumor and its metastasis in severe combined immunodeficient mice. Because metastasis is a multistep process, the aim of the present study was to investigate the effect of PS on some steps of the metastatic process: tumor cell invasion, adhesion, and migration. In addition, cell growth and cell cycle progression were evaluated. MDA-MB-231 cells were supplemented with cholesterol, beta-sitosterol, and campesterol. Cells were treated for 3 days with 16 microM sterol that was loaded on 5 mM cyclodextrin. beta-Sitosterol inhibited tumor cell invasion through Matrigel and adhesion of cells to plates coated with collagen I, collagen IV, fibronectin, and laminin compared with cholesterol treatments and controls. Cholesterol treatment resulted in increased adhesion to laminin and collagen IV, two basement membrane (BM) components that are implicated in signaling tumor cell invasion in this cell line. Only cholesterol treatment increased cellular migration. beta-Sitosterol inhibited cell growth by 70% compared with controls and induced cell cycle arrest at the G2/M phase. It is concluded that, among PS, beta-sitosterol may offer protection from breast cancer metastasis by inhibiting cell invasion of the BM, which may be mediated by its ability to limit the adhesive interaction of the tumor cell and the BM.     

Effect of branched-chain fatty acids on fatty acid biosynthesis of human breast cancer cells

This paper describes the antitumoral activity of branched-chain fatty acid (BCFA) in human breast cancer cells with an emphasis on its effect on fatty acid biosynthesis. First, the relationship between chain-length and antitumoral activity was studied. The highest activity was observed with iso-16:0, and the activity decreased with increase or decrease of the chain-lengths from C16:0. Anteiso-BCFA, as well as iso-series, was cytotoxic to the breast cancer cells. Cytotoxicity of BCFA was comparable to that of conjugated linoleic acid known as antitumoral fatty acid. Incubation of breast cancer cells with BCFA (13-methyltetradecanoic acid) significantly reduced the [14C] acetate incorporation into free fatty acid and fatty acid esters, showing the inhibition of fatty acid biosynthesis by BCFA. Examination of substrate level effect found that BCFA slightly inhibited fatty acid synthetase and acetyl-CoA carboxylase, and significantly the glucose-6-phosphate dehydrogenase which was the main NADPH generating system in breast cancer cells. The present study thus suggests that BCFA synthetically lowers the fatty acid biosynthesis by reducing the precursors, in addition to its direct inhibitory effect on fatty acid synthetase.     

Effects of dietary fish oil on fatty acids and eicosanoids in metastasizing human breast cancer cells

We examined the relationships between the suppressive effects of dietary fish oil on growth and metastasis of MDA-MB-435 human breast cancer cells in female nude mice and the primary tumor phospholipid fatty acid concentrations, phospholipase A2 activity, and eicosanoid levels. Mice (n = 120) were fed a 23% (wt/wt) corn oil (CO) linoleic acid (LA)-rich diet for seven days before and after 10(6) tumor cells were injected into a mammary fat pad, and then the mice receive one of three isocaloric diets containing 23% total fat but different proportions of CO and menhaden oil (MO) (18% CO-5% MO, 11.5% CO-11.5% MO, 5% CO-18% MO) or a 23% fat diet containing 18% deodorized fish oil supplemented with tocopherol and tert-butylhydroquinone antioxidants (FAO). Primary tumor growth rate was significantly greater in mice fed the 18% CO diet than in the three diets containing higher levels of fish oil (all p < 0.05). The 18% MO diet, but not the 11.5% MO or the 18% FAO diet, suppressed the development of lung metastases compared with the 18% CO diet. Increasing the proportion of MO relative to CO in the diets produced corresponding increases in the primary tumor phospholipid eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) concentrations and reductions in LA and arachidonic acid. There was a significant positive correlation between the LA concentration in these tumors and the extent of lung metastasis (r = 0.504). Tumor phospholipase A2 activity was unaffected by dietary MO intake. Prostaglandin E2 concentration was inversely correlated with phospholipid EPA (r = -0.484) and DHA (r = -0.439), but there was no relationship with lung metastasis. Tumor leukotriene B4 and 5-hydroxyeicosatetraenoic acid levels were not reduced by dietary MO. The 18% FAO- and the 18% MO-fed mice showed similar relationships for the phospholipid fatty acids and prostaglandin E2, despite the lack of effect on metastasis. The strong correlation between phospholipid LA levels and metastasis and the lack of an association with tumor eicosanoids suggest that the 18% MO diet inhibited metastasis because dietary LA was replaced by other fatty acids.     

Effects of retinoic acid isomers on apoptosis and enzymatic antioxidant system in human breast cancer cells

Retinoic acids (RAs) modulate growth, differentiation, and apoptosis in normal, pre-malignant & malignant cells. In the present study, the effects of RA isomers (all-trans RA, 13-cis RA, and 9-cis RA) on the cell signal transduction of human breast cancer cells have been studied. The relationship between RAs and an enzymatic antioxidant system was also determined. Estrogen-receptor (ER) positive MCF-7 and ER-negative MDA-MB-231 human breast cancer cells were treated with different doses of each RA isomers, all-trans RA, 13-cis RA, or 9-cis RA. Treatment of RA isomers inhibited cell viability and induced apoptosis of MCF-7 cells as a result of increased caspase activity in cytoplasm and cytochrome C released from mitochondria. All-trans RA was the most effective RA isomer in both cell growth inhibition and induction of apoptosis in MCF-7 cells. However, no significant effect of RA isomers was observed on the cell growth or apoptosis in ER-negative MDA-MB-231 cells. In addition, activities of antioxidant enzymes such as catalase and glutathione peroxidase were decreased effectively after treatment of RA in MCF-7 cells, whereas SOD activity was rarely affected. Thus, the present data suggest that all-trans RA is the most potential inducer of apoptosis and modulator of antioxidant enzymes among RA isomers in MCF-7 human breast cancer cells.