Catechol estrogens induce oxidative DNA damage and estradiol enhances cell proliferation

Estrogen-induced carcinogenesis involves enhanced cell proliferation (promotion) and genotoxic effects (initiation). To investigate the contribution of estrogens and their metabolites to tumor initiation, we examined DNA damage induced by estradiol and its metabolites, the catechol estrogens 2-hydroxyestradiol (2-OHE(2)) and 4-hydroxyestradiol (4-OHE(2)). In the presence of Cu(II), catechol estrogens formed piperidine-labile sites at thymine and cytosine residues in (32)P 5'-end-labeled DNA fragments and induced the formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine. NADH markedly enhanced Cu(II)-dependent DNA damage mediated by nanomolar concentrations of catechol estrogens. Catalase and bathocuproine inhibited the DNA damage, suggesting the involvement of H(2)O(2) and Cu(I). These results suggest that H(2)O(2), generated during Cu(II)-catalyzed autoxidation of catechol estrogens, reacts with Cu(I) to form the Cu(I)-peroxide complex, leading to oxidative DNA damage, and that NADH enhanced DNA damage through the formation of redox cycle. To investigate the role of estrogens and their metabolites in tumor promotion, we examined their effects on proliferation of estrogen-dependent MCF-7 cells. Estradiol enhanced the proliferation of MCF-7 cells at much lower concentrations than catechol estrogens. These findings indicate that catechol estrogens play a role in tumor initiation through oxidative DNA damage, whereas estrogens themselves induce tumor promotion and/or progression by enhancing cell proliferation in estrogen-induced carcinogenesis.     

敌百虫暴露对小鼠及胎鼠生殖发育影响

目的研究母鼠器官形成期经口暴露较低浓度的有机磷农药-敌百虫,对母鼠生殖功能、内分泌功能及胚胎发育的影响。方法孕鼠随机分为对照组和3个实验组,在胎儿器官形成期即妊娠第6～15d经口灌胃染毒敌百虫,剂量分别为0,12.5,25和50 mg/kg。在妊娠第17d经眼球取血后处死孕鼠,研究在本实验剂量下,敌百虫对孕鼠生殖功能、内分泌功能以及胚胎发育的影响。结果（1）母鼠器官形成期经口暴露敌百虫,可导致各实验组胎鼠外观畸形发生率显著增高（P〈0.01）。（2）各剂量敌百虫暴露对孕鼠的生育力及妊娠结局无明显影响,表现在孕鼠的体重、卵巢脏器系数、胎盘脏器系数、黄体数、着床率、活胎数、死胎数、吸收胎数等与对照组比较差异无统计学意义（P〉0.05）;（3）除50mg/kg剂量敌百虫的暴露可引起母鼠血清雌二醇浓度下降外,其他各剂量组母鼠血清和卵巢的雌二醇浓度均未见明显影响。结论在本实验剂量下,器官形成期雌鼠经口暴露敌百虫对子代胚胎的生长发育有影响,表现为胎鼠的畸形发生率增加,但对母鼠的生殖功能、内分泌功能未见明显影响。     

雌激素对去势小鼠脾细胞凋亡的作用机制探讨

目的:探讨雌激素对去势小鼠脾细胞凋亡、凋亡基因Fas、FasL及ER亚型表达的影响。方法:流式细胞仪检测不同浓度E2时去势小鼠脾细胞的凋亡率;RT-PCR方法检测细胞内Fas、FasL及ERα和ERβmRNA的表达。结果:除最低浓度(10-5μmol/L)外,去势+E2组凋亡率及Fas、FasL基因的表达都高于青年组(P<0.05);与去势对照组相比,E2在10-3μmol/L、10-2μmol/L浓度时凋亡率及Fas、FasL基因的表达增高(均P<0.01)。E2在10-4μmol/L时ERα、ERβ基因的表达升高(ERα:P<0.05;ERβ:P<0.01),以后随浓度增加ERα和ERβmRNA水平有下降去势。结论:高浓度E2致脾细胞凋亡,与上调凋亡促进基因Fas、FasL基因表达有关,低浓度E2可能逆转去势小鼠脾细胞凋亡。不同浓度E2对去势小鼠脾细胞ERα和ERβ基因表达的影响支持雌激素对ER表达的调节作用:在生理范围内为正向调节,超生理范围为负向调节。     

地塞米松上调禁欲的发情雄性小鼠睾丸间质细胞芳香化酶表达

目的:探讨地塞米松对禁欲的发情雄性小鼠睾丸组织芳香化酶表达的影响。方法:发情昆明雄性小鼠随机分成3组,每组10只:性表达组(A组)、禁欲组(B组)、地塞米松+禁欲组(C组,皮下给地塞米松16.66mg/kg),采用放射免疫法检测各组血清睾酮(T)、雌二醇(E2)水平以及睾丸组织E2含量;采用化学发光法检测血清皮质醇水平;采用原位杂交和免疫组织化学技术检测睾丸组织芳香化酶(P450arom)的表达。结果:C组睾丸间质细胞芳香化酶表达增强(P<0.01),睾丸组织、血清E2水平升高(P<0.01),而血清皮质醇水平降低(P<0.01)。结论:地塞米松可能通过抑制禁欲的发情雄性小鼠肾上腺皮质醇分泌而上调睾丸间质细胞P450arom表达。     

雌孕激素对子宫内膜细胞增殖凋亡的影响

目的探讨雌、孕激素对卵巢摘除大鼠子宫内膜凋亡和增殖的影响。方法SD雌性大鼠分为5组:假手术组(Sham)、卵巢摘除组(OVX)、卵巢摘除加肌注苯甲酸雌二醇组(OVX BE2)、卵巢摘除加肌注黄体酮组(OVX P)、卵巢摘除同时加肌注BE2和P组(OVX BE2 P),实验组分别在激素作用5、10周后取材。流式细胞术(FCM)及TUNEL法分别检测内膜细胞凋亡与增殖情况,SP法检测子宫内膜PCNA的活性表达。结果OVX BE2组的增殖率明显升高;OVX P组、OVX BE2组、OVX BE2 P组凋亡率均显著减少。结论雌、孕激素影响子宫内膜上皮细胞的增殖与凋亡,是激素调控内膜的机制之一。     

Successful co‐treatment with LHRH‐agonist for ovarian over‐stimulation and cystic formation in premenopausal tamoxifen exposure

The present study evaluates the potential beneficial effect of cotreatment with LHRHagonist in resolving premenopausal tamoxifen's induced supraphysiological serum 17 estradiol levels and persistent ovarian cysts. Ultrasonographic and serum hormonal evaluations were performed before, during, and following three consecutive injections of long acting LHRHagonist administered to 14 premenopausal breast cancer patients treated with tamoxifen, who had supraphysiological serum 17 estradiol levels and simultaneous persistent ovarian cysts. Within 3 weeks of the first LHRHagonist injection, all patients had menopausal serum estradiol levels. Ovarian cysts completely disappeared within 2 months following the first injection. Following the discontinuation of LHRHagonist cotreatment, serum estradiol levels remained in physiological levels and the ovaries remained a normal size in 64.3% of the patients for 13.3 ± 11.5 months. 28.6% of the patients had a gradual reappearance of high serum estradiol levels and of ovarian cysts, and were, therefore, treated with a second course of LHRHagonist. Following the second course, serum estradiol levels remained in physiological levels and the ovaries remained a normal size for 8–15 months. It is concluded that short duration of cotreatment with long acting LHRHagonist administered to premenopausal breast cancer patients treated with tamoxifen, successfully resolved the tamoxifeninduced supraphysiological serum 17 estradiol levels and the ovarian cysts.affiliated with Sackler Faculty of Medicine, Tel Aviv University     

17β-雌二醇对脂蛋白诱导内皮细胞产生炎性细胞因子的影响

目的：研究低脂蛋白（ＬＤＬ）和氧化低密度脂蛋白（ｏｘＬＤＬ）对内皮细胞产生炎性细胞因子白细胞介素６（ＩＬ－６）和肿瘤坏死因子（ＴＮＦ）的影响及１７β－雌二醇对此的作用。方法：经体外培养的人脐静脉内皮细胞（ＨＵＶＥＣ）为模型。将ＬＤＬ、ｏｘＬＤＬ与ＨＵＶＥＣ孵育,及ＨＵＶＥＣ经他莫昔芬（ｔａｍｏｘｉｆｅｎ）和（或）１７β－雌二醇预处理后,再与ＬＤＬ、ｏｘＬＤＬ孵育,检测培养液中ＩＬ－６和ＴＮＦ活性。     

人胎儿卵巢培养时雌二醇的分泌

19例16～30孕周的人胎儿卵巢经体外培养以观察培养前、后及加入不同比例促性腺激素培养后培养液中雌二醇(E_2)值的释放值,培养时间最长达6d。经体外培养的卵巢组织均具有分泌E_2的能力。16～19 6/7周的胎儿卵巢与FSH、LH培养1d,比不加激素组产生更多的E_2(P<0.05)。说明人胎儿卵巢自16周起就具有对促性腺激素作出反应的能力。24～30周的卵巢在加入FSH:LH为4:1(FSH1.33IU/ml,LH0.33IU/ml)经3d培养,可以产生更多的E_2(P<0.05)。上述现象与人胎儿卵巢的形态学研究资料相符。     

17β-雌二醇对卵巢切除小鼠海马内脑源性神经营养因子及神经营养因子 3表达的影响(英文)

目的　为确定雌激素可能具有的神经营养调节作用。方法　采用蛋白质印迹法检测上述指标的变化。结果　与卵巢未切除对照组相比 ,小鼠卵巢切除 10周后海马内脑源性神经营养因子 (BDNF)表达水平明显下降 ,给予 17β 雌二醇 (2 .4或 4 .8μg·d- 1,sc ,连续 12周 )替代具有明显的改善作用 (P <0 .0 1)。但卵巢切除及 17β 雌二醇替代对海马内神经营养因子 3表达水平无明显影响。结论　海马内BDNF表达水平的改变与雌激素缺乏具有密切关系。雌激素对调节海马内BDNF水平具有重要作用。