DACT1, an antagonist to Wnt/β-catenin signaling,suppresses tumor cell growth and is frequently silenced in breast cancer

Introduction

Aberrant activation of Wnt/β-catenin signaling plays an important role in the pathogenesis of breast cancer. DACT1 (Dapper/Frodo) has been identified as involved in antagonizing Wnt/β-catenin signaling through interacting with Dishevelled (Dvl), a central mediator of Wnt signaling, whereas its role in breast tumorigenesis remains unclear.

Methods

We examined DACT1 expression in breast cancer cell lines and primary tumors with semiquantitative or quantitative RT-PCR and immunochemistry, and further evaluated the promoter methylation of DACT1 with methylation-specific PCR (MSP). We also explored the tumor-suppressive functions of DACT1 in vivo and in vitro, and its related mechanism in breast cancer.

Results

We identified DACT1 as a methylated target in our breast cancer epigenome study. Here, we further investigated DACT1 expression in multiple breast cell lines and primary tumors, and further studied its function and molecular mechanisms. We found that DACT1 expression was silenced in eight (88.9%) of nine breast cancer cell lines, and its protein levels were obviously reduced in breast tumors compared with paired surgical-margin tissues. Promoter CpG methylation of DACT1 was detected in five (55.6%) of nine breast cancer cell lines and 40 (29.9%) of 134 primary tumors, but not in surgical-margin tissues and normal breast tissues. Demethylation treatment of breast cancer cell lines restored DACT1 expression along with promoter demethylation, suggesting that an epigenetic mechanism mediates DACT1 silencing in breast cancer. Functional assays showed that ectopic expression of DACT1 could inhibit breast tumor cell proliferation in vivo and in vitro through inducing apoptosis, and further suppress tumor cell migration through antagonizing the Wnt/β-catenin signaling pathway.

Conclusions

Our study demonstrates that DACT1 could function as a tumor suppressor but was frequently downregulated in breast cancer.     

宫腔镜手术前米索前列醇不同给药方案的临床研究

目的：米索前列醇不同用药方案作为宫腔镜手术前宫颈预处理的临床效果比较。方法：随机的前瞻性研究。组Ⅰ和组Ⅱ：米索0．6mg和0．4mg阴道给药；组Ⅲ和组Ⅳ：米索0．6mg和0．4mg口服给药。观察并记录宫颈软化程度、术中疼痛评分（VRS）、手术时间及不良反应的情况。结果：四组宫颈软化程度比较差异有显著性（P〈0．01）；四组的手术时间及膨宫液用量比较差异无显著性（P〉0．05）；组Ⅰ、组Ⅱ和组Ⅲ各组间疼痛程度比较差异无显著性（P〉0．05）。组Ⅲ的腹泻、下腹痛的发生率与其他各组之间比较差异性有显著性（P〈0．05）。结论：宫腔镜手术前4h阴道放置0．4mg的米索，用药剂量小、副反应轻、宫颈松软适度，是理想的宫颈预处理方案。     

似昼夜节律对小鼠视网膜电图的影响

目的:观察不同时间对昆明、BALB/C,C57BL/6J小鼠视网膜电图(electroretinography,ERG)的影响,探讨小鼠ERG的似昼夜节律改变。方法:将各品系小鼠分为6组,每组5只,分别在4:00～8:00,08:00～12:00,12:00～16:00,16:00～20:00,20:00～24:00,24:00～4:006个时间区间,按照国际临床视觉电生理标准化方案进行暗适应ERG(ScotERG),最大混合反应(MaxERG),明适应ERG(PhotoERG)记录。结果:各品系小鼠视网膜电图表现较为规律的节律性,在20:00～24:00区间其ERG的b波幅值最高,在4:00～8:00区间开始下降,在12:00～16:00区间b波幅值最低。明适应ERG的b波幅和暗适应b波幅值有相反的节律性。结论:不同品系小鼠视网膜光敏感性有较规律的节律性,可能和小鼠的活动规律有关,时间节律的影响能严重的影响小鼠视觉电生理检查的稳定性。     

Experimental Verification of the Elastic Formula for the Aspirated Length of a Single Cell Considering the Size and Compressibility of Cell During Micropipette Aspiration

In this study, an aspiration system for elastic spheres was developed to verify the approximate elastic formula for the aspirated length of a single solid-like cell undergoing micropipette aspiration (MPA), which was obtained in our previous study by theoretical analysis and numerical simulation. Using this system, foam silicone rubber spheres with different diameters and mechanical properties were aspirated in a manner similar to the MPA of single cells. Comparisons between the approximate elastic formula and aspiration experiments of spheres indicated that the predictions of the formula agreed with the experimental results. Additionally, combined with the MPA data of rabbit chondrocytes, differences in terms of the elastic parameters derived from the half-space model, incompressible sphere model, and compressible sphere model were explored. The results demonstrated that the parameter ξ (ξ?=?R/a, where R is the radius of the cell and a is the inner radius of the micropipette) and Poisson’s ratio significantly influenced the determination of the elastic modulus and bulk modulus of the cell. This work developed for the first time an aspiration system of elastic spheres to study the elastic responses of the MPA of a single cell and provided new evidence supporting the use of the approximate elastic formula to determine cellular elastic parameters from the MPA data.     

覆膜气管支架治疗全肺切除术后支气管胸膜瘘

目的:初步探讨覆膜气管支架治疗全肺切除术后支气管胸膜瘘的可行性。方法:应用覆膜气管支架治疗全肺切除术后支气管胸膜瘘2例。结果:2例分别经20d和35d胸腔冲洗而痊愈,随访期间无复发。结论:覆膜气管支架为全肺切除术后支气管胸膜瘘治疗提供了一个安全、有效的方法。     

柠檬酸发酵液的活性炭吸附处理法

提出了用活性炭吸附处理柠檬酸发酵液的工艺条件及流程。探讨了湿度、通量、停留时间、再生碱液浓度等对吸附、脱附操作的影响。解决了萃取法制柠檬酸操作时的界面污物现象，为充实该法制柠檬酸提供了依据。     

加减龙胆泻肝汤对肝经郁火型多囊卵巢综合征患者卵泡膜细胞P450c17酶的影响

目的：探讨加减龙胆泻肝汤治疗肝经郁火型多囊卵巢综合征（polycystic ovary syndrome，PCOS）的作用机理。方法：将正常卵巢与多囊卵巢卵泡膜细胞分离并进行体外培养，加入含不同药物的血清培养液培养，检测雄烯二酮和17羟孕酮。结果：雄烯二酮和17羟孕酮的含量在正常高剂中药组、正常低剂中药组、正常胰岛素组与正常血清组比较无显著性差异（P〉0．05）；在多囊血清组显著高于正常血清组（P〈0．05）；在多囊高剂中药组显著低于多囊血清组（P〈0．05），在多囊低剂中药组与多囊血清组比较无显著性差异（P〉0．05）；在多囊高剂中药组与正常血清组无显著性差异（P〉0．05）；在多囊胰岛素组显著高于多囊血清组（P〈0．05）。结论：通过降低P450c17酶的活性改善高雄激素血症可能是疏肝泻火中药治疗PCOS的疗效机理之一；胰岛素在肝经郁火型PCOS中并非起到发病的启动作用，而是在PCOS患者卵泡膜细胞P450c17酶活性改变的基础上，起到了加重作用；疏肝泻火中药对卵泡膜细胞P450c17酶活性具有双重调节作用。     

人骨髓间充质干细胞体外分离培养的实验研究

目的探索体外分离培养人骨髓间充质干细胞的方法并观察基本生长特性，为今后研究其分化提供实验依据。方法：采用Ficoll-Paque淋巴细胞分离液分离人骨髓间充质干细胞，体外培养扩增，在倒置相差显微镜下观察细胞形态变化，细胞计数法绘制生长曲线，流式细胞仪检测细胞周期。结果：密度梯度离心法可获得较高纯度的骨髓间充质干细胞，细胞形态呈圆形、三角形或棒杆状，48h后细胞开始贴壁，4-5d可见有集落形成，2w左右可达到基本融合。生长曲线示骨髓间充质干细胞增殖活跃，流式细胞仪检测显示约有86％的细胞处于G0、G1期。结论：人骨髓间充质干细胞在体外培养条件下生长性状稳定，增殖能力较强，可作为肝组织工程中理想的种子细胞来源。     

龈沟液超氧化物歧化酶活性与牙周炎的关系

目的：探讨龈沟液超氧化物歧化酶（ＳＯＤ）活性与牙周炎症的关系。方法：采用邻苯三酚法检测性成人牙周炎患者龈沟液ＳＯＤＩ舔生。结果：牙周炎症牙位龈沟液ＳＯＤ活性显著低于健康牙位,且随牙组织炎性破坏的加重明显降低,在治疗后又明显回升,与牙龈指数、附着丧失、探针深度等牙周临床指标呈高度负相关。结论：龈沟液ＳＯＤ活性与牙炎症的的发生和发展有密切关系,可作为牙周炎症的临床参考指标。     

Effects of mitomycin C on the expression of proliferating cell nuclear antigen after filtering surgery in rabbits

Background: The aim of the study was to evaluate the effects of mitomycin C on the cell replication activity in wound healing following experimental filtration surgery. Methods: Trabeculectomy with or without application of mitomycin C was performed on albino rabbit eyes. At 1, 4, 7, 14, and 28 days after surgery, the expression of proliferating cell nuclear antigen, a marker of cell proliferation, in the filtering site was examined immunohistochemically using a streptavidin-biotin complex method. Results: In control eyes that underwent trabeculectomy but did not receive mitomycin C, the number of immunoreactive cells increased 4–7 days after operation and decreased markedly at around 14 days. The filtering site was obstructed histologically at 4–7 days after operation. In the mitomycin C-treated eyes, immunoreactive cells appeared 4 days after surgery but disappeared by 7 days at the surgical site. The number of immunoreactive cells in the treated eyes was much lower than that in control eyes. Conclusion: The cell replication activity was markedly inhibited by administration of mitomycin C. The filtering site remained open for 28 days after surgery, whereas it was completely obstructed within 7 days in control eyes. Immunocytochemistry for proliferating cell nuclear antigen, as used in this study, is a simple and reliable method for detection of cell replication activity.