Common Molecular Mechanisms of Mammary Gland Development and Breast Cancer

During its lifetime, the mammary gland undergoes many phases of development and differentiation. Much of this occurs during puberty, when the ductal epithelium expands by branching morphogenesis, invading the surrounding fat pad to form an organised mammary tree. Throughout its existence, the epithelium will go through several cycles of proliferation and cell death during pregnancy, lactation and involution. Many of the signalling mechanisms which control the initial invasion of the fat pad by the epithelium, and regulate its continuing plasticity, can be harnessed or corrupted by tumour cells in order to support their aberrant growth and progression towards invasion. This is true not just for the epithelial cells themselves but also for cells in the surrounding microenvironment, including fibroblasts, macrophages and adipocytes. This review examines the complex web of signalling and adhesion interactions controlling branching morphogenesis, and how their alteration can promote malignancy. Current in vivo and in vitro mammary gland models are also discussed. (Part of a Multi-author Review)     

Common Molecular Mechanisms of Mammary Gland Development and Breast Cancer

Hypoxia affects many important processes in tumour progression and is a key feature in the tumour microenvironment that needs to be taken into account when evaluating prognostics and therapeutic options for cancer patients. Hypoxia-regulating proteins, i.e. hypoxia inducible factors (HIFs), and associated gene products have been linked to certain tumour behaviours and might be useful as prognostic and predictive markers. Recently, hypoxia-driven gene products have been launched as novel cancer treatment targets with the potential to increase tumour-specific effects. Breast cancer consists of a multitude of different diseases with certain common characteristics, but also clearly disparate behaviours and genetic alterations. In this review we will summarise the role of hypoxia in breast cancer and specifically outline the importance of hypoxia and HIF-1alpha regarding prognostic and treatment-specific implications. (Part of a Multi-author Review).     

Common Molecular Mechanisms of Mammary Gland Development and Breast Cancer

Evidence is accumulating that breast cancer is not one disease but many separate diseases. DNA microarray-based gene expression profiling has demonstrated subtypes with distinct phenotypic features and clinical responses. Prominent among the new subtypes is 'basal-like' breast cancer, one of the 'intrinsic' subtypes defined by negativity for the estrogen, progesterone, and HER2/neu receptors and positivity for cytokeratins-5/6. Focusing on basal-like breast cancer, we discuss how molecular technologies provide new chemotherapy targets, optimising treatment whilst sparing patients from unnecessary toxicity. Clinical trials are needed that incorporate long-term follow-up of patients with well-characterised tumour markers. Whilst the absence of an obvious dominant oncogene driving basal-like breast cancer and the lack of specific therapeutic agents are serious stumbling blocks, this review will highlight several promising therapeutic candidates currently under evaluation. Thus, new molecular technologies should provide a fundamental foundation for better understanding breast and other cancers which may be exploited to save lives. (Part of a Multi-author Review).     

Common Molecular Mechanisms of Mammary Gland Development and Breast Cancer

Cancer cell invasion involves the breaching of tissue barriers by cancer cells, and the subsequent infiltration of these cells throughout the surrounding tissue. In breast cancer, invasion at the molecular level requires the coordinated efforts of numerous processes within the cancer cell and its surroundings. Accumulation of genetic changes which impair the regulation of cell growth and death is generally accepted to initiate cancer. Loss of cell-adhesion molecules, resulting in a loss in tissue architecture, in parallel with matrix remodelling may also confer a motile or migratory advantage to breast cancer cells. The tumour microenvironment may further influence the behaviour of these cancer cells through expression of cytokines, growth factors, and proteases promoting chemotaxis and invasion. This review will attempt to summarise recent work on these fundamental processes influencing or facilitating breast cancer cell invasion. (Part of a Multi-author Review).     

循环雌二醇及代谢物与绝经后乳腺癌的相关性

目的探讨循环雌二醇（E2）、4-羟雌二醇（4-OHE2）、2-甲氧雌二醇（2-MOE2）水平及4-羟雌二醇：2-甲氧雌二醇（4-OHE2：2-MOE2）比值与绝经后乳腺癌危险性的相关性。方法采用ELISA法检测绝经后34例乳腺癌、40例乳腺良性（乳腺纤维腺瘤与乳腺囊性增生病）疾病患者和20例正常对照循环雌二醇、4-羟雌二醇、2-甲氧雌二醇水平并计算4-羟雌二醇：2-甲氧雌二醇比值。结果乳腺癌组及乳腺良性疾病组循环2-甲氧雌二醇水平差异无统计学意义（P〉0．05）,但均较正常对照组低（P〈0．05）;乳腺癌组及乳腺良性疾病组4-羟雌二醇：2、甲氧雌二醇比值差异无统计学意义（P〉0．05）,但均较正常对照组升高（P〈0．05）。乳腺癌Ⅰ期～Ⅲ期各期循环雌二醇、4．羟雌二醇、2-甲氧雌二醇、4-羟雌二醇：2-甲氧雌二醇比值差异无统计学意义（P〉0．05）。4-羟雌二醇、2．甲氧雌二醇、4．羟雌二醇：2-甲氧雌二醇比值在乳腺癌ER（-）组与ER（＋）组间差异无统计学意义（P〉005）,但ER（＋）组雌二醇水平较ER（-）组明显升高（P〈0．05）。结论2．甲氧雌二醇与绝经后乳腺疾病负相关;4-羟雌二醇：2-甲氧雌二醇比值可能预示绝经后乳腺疾病危险。     

MDM2启动子SNP309多态性与亚洲人群乳腺癌易感性关系的Meta分析

目的探讨MDM2基因启动子309位点多态性与亚洲人群乳腺癌易感性的关系。方法计算机检索Pub Med、EMBASE、Cochrane Library、中国期刊全文数据库、中国生物医学文献数据库、中文科技期刊数据库和万方数据库,收集MDM2基因SNP309多态性与亚洲人乳腺癌易感性关系的相关文献,然后用Stata软件进行亚组分析、敏感性分析和文献的发表偏倚检验。结果病例组和对照组相比,显性模型(GG+TG vs TT:OR=1.012,95%CI为0.56~1.83)、隐性模型(GG vs TG+TT:OR=1.10,95%CI为0.65~1.263)和等位基因模型(G vs T:OR=1.012,95%CI为0.81~1.83),共显性模型(GG vs TT:OR=0.86,95%CI为0.49~1.58),无统计学意义。结论在亚洲人群患者人群中,携带MDM2SNP309不会提高乳腺癌的发病风险。     

不同转移潜能乳腺癌细胞中EGFR的表达及意义

目的 研究表皮生长因子受体（epidermal growth factor receptor,EGFR）在不同转移潜能乳腺癌细胞中的表达,并探讨其在乳腺癌侵袭转移过程中的作用. 方法 利用人工基质膜侵袭实验获得高、低转移潜能乳腺癌细胞亚系,四甲基偶氮唑盐（MTT）法检测两系细胞生长曲线和倍增时间,流式细胞仪检测两系细胞周期,transwell侵袭小室模型比较两系的迁移能力.应用逆转录聚合酶链反应（RT-PCR）和免疫印迹（Western Blot）检测EGFR在两系细胞中的表达. 结果 利用transwell小室成功筛选出高、低转移潜能乳腺癌细胞亚系;它们的体外生长速度、倍增时间、细胞周期和侵袭力具有明显差异;RT-PCR和Western Blot均显示在高转移潜能乳腺癌细胞中EGFR在基因和蛋白水平的表达均显著高于低转移乳腺癌细胞. 结论 EGFR的过表达与乳腺癌细胞侵袭能力显著性相关,EGFR在乳腺癌侵袭过程中发挥了重要的作用.     

沉默Maspin基因对人乳腺癌细胞MCF-7侵袭迁移能力的影响

目的 探讨靶向沉默maspin基因对乳腺癌MCF-7细胞侵袭和迁移能力的影响.方法 构建针对maspin基因的具有荧光蛋白表达的shRNA真核表达载体,稳定转染入乳腺癌细胞MCF-7中.通过划痕实验和Transwell小室侵袭实验分别观察转染前后细胞迁移及侵袭能力的影响.分别用RT-PCR及Western Blot检测转染重组质粒前后细胞maspin mRNA和蛋白表达情况.结果 成功构建表达质粒pGenesil-HK、pGenesil-maspin-1和pGenesil-maspin-2,并成功稳定转染MCF-7细胞.与未转染组和pGenesil-HK组相比,转染pGenesil-maspin-1和pGenesil-maspin-2后的MCF-7细胞划痕伤口愈合速度加快(P＜0.05),细胞侵袭至小室下层的细胞数明显高于对照组(P＜0.05).RT-PCR及Western Blot结果表明转染pGenesil-maspin-1和pGenesil-maspin-2后的细胞maspin的mRNA和蛋白表达明显下降.结论 靶向maspin基因的RNA干扰能够下调maspin基因在乳腺癌MCF-7细胞中的表达,并能增强肿瘤细胞的侵袭和迁移能力.     

COX-2与CYPlBl在人乳腺癌中的表达及意义

目的探讨人乳腺癌组织中COX-2和CYPlBl的表达规律及与临床病理特征的关系,对认识其在乳腺癌发生发展中的作用奠定初步病理学基础。方法应用免疫组织化学方法检测42例乳腺癌组织中COX-2和CYPlBl的表达情况,结合临床病理指标进行研究分析。结果在乳腺癌中COX-2和CYPIBl表达阳性率分别为78．6％和73．8％。COX-2的阳性表达与乳腺癌淋巴结转移、组织学分级显著相关（P〈0．05）;CYPlBI的阳性表达与组织学分级、ER表达显著相关（P〈0．05）。乳腺癌COX-2与CYPlBI表达呈正相关（r=0．481,P〈0．01）。结论人乳腺癌组织存在COX-2与CYPlBl的共同阳性表达,COX-2可能促进CYPlBl表达,共同作用参与乳腺癌的发生发展。     

Curcumin通过Wnt信号通路抑制乳腺癌细胞MCF-7增殖的研究

目的 观察姜黄素(Curcumin)对乳腺癌细胞MCF-7增殖的影响,以及对细胞内Wnt信号通路的影响,探索Curcumin可能存在的抑制乳腺癌细胞增殖的分子机制.方法 体外培养人乳腺癌细胞MCF-7,并用不同浓度的Curcumin作用不同的时间.用MTT检测Curcumin对MCF-7细胞生长情况的影响;流式细胞仪观察经Curcumin作用后细胞周期的改变;RT-PCR和Westernblot分别检测细胞内β -catenin和下游靶基因CyclinD1的mRNA和蛋白水平的表达.结果 MTT结果显示Curcumin可以抑制MCF-7的增殖,并具有剂量-时间依赖性.在浓度为20 μmol·L-1时,对细胞生长的抑制作用最为明显.流式细胞仪观察细胞周期的结果提示,Curcumin能够阻止MCF-7细胞由G1期进入S期,提高Go/G1期细胞的百分比.RT-PCR和Western blot结果显示,Curcumin显著降低了细胞内β-catenin和CyclinD1的mRNA和蛋白水平的表达,且呈剂量-时间依赖性.结论 Curcumin能够抑制MCF-7细胞胞浆内β -catenin蛋白进入胞核,阻断Wnt信号转导通路.进而抑制下游靶基因CyclinD1的表达,阻止MCF-7由G1期进入S期,有效抑制了MCF-7细胞的增殖.     

Mechanisms and consequences of intestinal dysbiosis

The composition of the gut microbiota is in constant flow under the influence of factors such as the diet, ingested drugs, the intestinal mucosa, the immune system, and the microbiota itself. Natural variations in the gut microbiota can deteriorate to a state of dysbiosis when stress conditions rapidly decrease microbial diversity and promote the expansion of specific bacterial taxa. The mechanisms underlying intestinal dysbiosis often remain unclear given that combinations of natural variations and stress factors mediate cascades of destabilizing events. Oxidative stress, bacteriophages induction and the secretion of bacterial toxins can trigger rapid shifts among intestinal microbial groups thereby yielding dysbiosis. A multitude of diseases including inflammatory bowel diseases but also metabolic disorders such as obesity and diabetes type II are associated with intestinal dysbiosis. The characterization of the changes leading to intestinal dysbiosis and the identification of the microbial taxa contributing to pathological effects are essential prerequisites to better understand the impact of the microbiota on health and disease.     

学习和记忆的神经基础

学习和记忆是脑是基本的高级功能,是我们每时每刻都在经历着的事情。学习和记忆过程中脑内发生了什么？在过去的２０多年中,有关学习和记忆的神经机制研究取得了重大进展。     

神经退行性疾病病变机理及药物作用新靶点

神经退行性疾病是医学研究领域中的一大难题,近年来,该类疾病遗传因素及病变机理的研究取得了很大进展。研究表明这类疾病的发生与某些基因突变后产生的蛋白有关,这些蛋白可进而直接或间接地引起一系列反应,影响神经系统中某些特定的神经细胞,最终导致这些细胞死亡。     

Mechanisms of transfer between environment and cell

Résumé Un essai de choix entre plusieurs mécanismes théoriques du transport actif dans les cellules, dans des conditions d'équilibre de flux, n'apparaît pas satisfaisant à la lumière de cette étude. Des analyses cinétiques capables de constituer les séparations désirées entre ces mécanismes sont présentées.     

Mechanisms of circulatory homeostasis and response inAplysia

This review concerns the organization and function of arterial vasculature inAplysia californica, especially the vasomotor reflexes that support circulatory homeostasis, and fixed patterns of response that may reroute blood flow during changes in behavioral state. The observations presented here raise three hypotheses for further study: 1)Arterial vasculature is functionally organized with precisely structured, independently regulated subdivisions; these are most evident for arterial systems serving digestive and reproductive processes; 2) arterial musculature is inherently responsive to local pressure changes, having both static and dynamic reflexes that promote efficient, evenly-distributed flow of blood; and 3) complex, long-lasting behaviors like egg laying have, as part of their makeup, equally prolonged and stereotypical changes in the pattern of circulation. Taken together, these observations support the view that maintenance and adjustment of blood flow in gastropod molluscs is an unexpectedly complex and highly integrated component of behavior.     

Common and differential mechanisms of gonadotropin receptors

The gonadotropin receptors are G-protein-coupled receptors with unique structural and functional features, consisting of two halves. The N-terminal extracellular half (exodomain) binds the hormones, whereas the C-terminal membrane-associated half (endodomain) is responsible for receptor activation. In this review, the novel ternary interactions, contact points and mutual modulations among the exodomain, endodomain and hormone for hormone binding and signal generation are described based on the latest observations. This discussion is contrary to the view that the exodomain and endodomain are independent, at least functionally, and provides new insights into the receptor mechanisms for the gonadotropins and other G-protein-coupled receptors. Received 7 November 2001; received after revision 2 January 2002; accepted 3 January 2002