BMP-6 inhibits microRNA-21 expression in breast cancer through repressing 6EF1 and AP-1

MicroRNAs （miRNAs）, which are small noncoding RNA molecules, play important roles in the post-transcriptional regulation process. The microRNA-21 gene （miR-21） has been reported to be highly expressed in various solid tumors, including breast cancer. Bone morphogenetic protein-6 （BMP-6） has been identified as an inhibitor of breast cancer epithelial-mesenchymal transition （EMT） through rescuing E-cadherin expression. We initiated experi- ments to identify the relationships between miR-21 and BMP-6 in breast cancer progression. Real-time PCR analysis showed that miR-21 expression was very high in MDA-MB-231 cells that expressed little BMP-6. A reverse correla- tion between BMP-6 and miR-21 was also determined in breast cancer tissue samples. Moreover, BMP-6 inhibited miR-21 transcription in MDA-MB-231 cells. In order to investigate how BMP-6 inhibited the miR-21 promoter （miPPR-21）, we constructed a series of miPPR-21 reporters. Luciferase assay results indicated that BMP-6 inhibited miPPR-21 activity through the E2-box and AP-l-binding sites. We also demonstrated that both δEF1 and TPA in- duced miR-21 expression. Using site-directed mutation and CHIP assay, we found that δEF1 induced miPPR-21 ac- tivity by binding to the E2-box on miPPR-21. Moreover, TPA triggered miPPR-21 activity through the AP-I binding sites. BMP-6 treatment significantly reduced the binding of these factors to miPPR-21 by decreasing the expression of δEF1 and c-Fos/c-Jun. We also demonstrated that BMP-6-induced downregulation of miR-21 modified the activ- ity of PDCD4 3＇UTR and inhibited MDA-MB-231 cell invasion. δEF1 overexpression and TPA induction blocked this inhibitory effect of BMP-6. In conclusion, BMP-6-induced inhibition of miR-21 suggests that BMP-6 may function as an anti-metastasis factor by a mechanism involving transcriptional repression of miR-21 in breast cancer.

大鼠脑梗死后缺氧组织显像的动态变化

【目的】研究大鼠脑梗死后缺氧组织是否能长期存在及其动态变化。【方法】利用大鼠大脑中动脉闭塞(MCAO)模型,分别采用99Tcm-HL91放射自显影和EF5免疫荧光的方法进行缺氧显像。分持续缺血组(PI)、1.5h缺血再灌注组(1.5hIR)、2h缺血再灌注组和3h缺血再灌注组4组,放射自显影的观察时间点选取手术后1d和14d,免疫荧光则选取术后1、3、7、14、21d,每个时间点各3只大鼠。【结果】放射自显影显示1.5hIR组手术后1d和14d均为缺氧阳性,其余各组均阴性;免疫荧光示1.5hIR组术后1、3、7和14d均有缺氧组织,面积(μm2)有缩小倾向(分别为21478±8254、4405±1490、2647±463和1612±239),但荧光强度没有明显减弱(分别为1.66±0.07、1.75±0.02、1.68±0.08和1.64±0.01);而其余各组在术后7d均已无缺氧组织。【结论】与人类脑梗死相似,大鼠脑梗死后缺氧组织可存在较长时间,且随着时间的延长而逐渐减少;1.5hIR的大鼠MCAO模型是研究脑梗死后缺氧组织长时间存在的合适模型。

Long-term existence of cerebral hypoxic tissue in a rat model of cerebral ischemia/reperfusion injury

BACKGROUND： Hypoxic tissue surrounding the ischemic core may represent the ischemic penumbra following cerebral infarction. However, some studies have shown that the duration of ischemic tissue is longer than previously believed. OBJECTIVE： To clarify whether cerebral hypoxic tissue could survive long-term and whether it is altered in rats following cerebral infarction; to establish an ischemiaJreperfusion model in which hypoxic tissue exists for extended periods of time. DESIGN, TIME AND SE＇I-I＇ING： A completely randomized grouping and controlled experiment was performed at the Experimental Animal Center of Sun Yat-sen University and Medical Research Center, the Second Affiliated Hospital of Sun Yat-sen University between June and December 2008. MATERIALS： 4,9-diaza-3,3,10,10-tetramethyldodecan-2, 11 -dione dioxime （BnAO） （HL91）, used as the hypoxic marker for autoradiography, was supplied by the Beijing Syncor Star Medicinal, China, and the flesh eluent Na99TcmO4 to mark HL91 was supplied by Guangzhou Medical Isotope Center of the China Institute of Atomic Energy. 2-（2-nitro-1H-imidazole-l-yl）-N-（2,2,3,3,3-pentafluoropropyl） acetamide （EF5） and its antibody ELK3-51, used as a hypoxic marker for immunofluorescence, were supplied by the University of Pennsylvania, USA. METHODS： Male Sprague Dawley rats were randomly divided into four groups： 1.5-hour ischemiaJreperfusion group （1.5 h IR）, 2-hour ischemiaJreperfusion group （2 h IR）, 3-hour ischemiaJreperfusion group （3 h IR）, and permanent ischemia （PI） group, with 21 rats in each group. The middle cerebral artery occlusion model was established using the intraluminal suture method, while reperfusion was performed by removing the suture at each observation time point. However, in the PI group, the suture was left in the artery. MAIN OUTCOME MEASURES： Area and average absorbance of fluorescence, representing hypoxic tissue, were measured by image-analysis. RESULTS： Autoradiography revealed positive hypoxia at days 1 and 14 postoperatively in the 1.5 h IR group. Immunohistochemistry results demonstrated that hypoxic tissue existed in the 1.5 h IR group on days 1, 3, 7, and 14, with decay of the area, but no significant weakening of fluorescent intensity. Hypoxic tissues were not observed at day 7 postoperatively in the 2 h and 3 h IR groups, as well as PI group. CONCLUSION： Similar to human cerebral infarction, hypoxic tissues in rats exist for an extended period of time following cerebral infarction, and diminish over even longer periods. Moreover, the 1.5 h IR rat model was the suitable model for studying long-term hypoxic tissue after cerebral infarction.

Magnetic Resonance Spectroscopy and Prognostic Analysis of Molecular Subtypes of Medulloblastoma

Aim: The aim of this study was to investigate whether magnetic resonance spectrum (MRS) and MR imaging features can be used for non-invasive medulloblastoma subgrouping, and analyse patient characteristics and prognosis of molecular subtypes of medulloblastoma. Material and Methods: 32 patients with medulloblastoma underwent MRI prior to surgical resection, 16 of them underwent MRS. MR imaging features and metabolites measured by MRS were analysed to distinguish molecular subtypes of medulloblastoma. Patient demographics, histopathological types, and prognosis of different molecular subtypes were analysed and compared respectively. Results: MRS and MR imaging features differed from different individuals, but without statistical significance that involves acquiring non-quantitative MR imaging features and NAA/Cr, Cho/Cr, Lip/Cr, Glu and Gln/Cr ratio, to be used to determine molecular subtypes. There was no significant difference of the three molecular subtypes in age, gender and pathological type. The 5-year event-free survival (EFS) of SHH, WNT and non SHH/WNT subtype respectively were 75%, 57.1%, 38.1%, with no significant difference (p = 0.382). 5-year EFS of non SHH/WNT subtype was significantly higher in ≤3 years old group than >3 years old group (p = 0.047). Conclusion: MRS and MR imaging features can’t be used to determine molecular subtypes based on our small sample study. There was no significant difference of the prognosis in the three molecular subtypes. The prognosis of ≤3 years old group of non SHH/WNT subtype is better than >3 years old group.

大孔吸附树脂分离纯化淫羊藿EF5黄酮

目的:采用HPLC法和UV法监测AB-8大孔吸附树脂分离纯化以淫羊藿苷、朝藿定A、朝藿定B、朝藿定C和宝藿苷I这五种黄酮为主要成分的淫羊藿EF5黄酮并筛选出最佳分离纯化工艺参数。方法:采用UV法,以淫羊藿总黄酮洗脱率为指标,考察树脂对淫羊藿总黄酮的吸附容量、解吸附率、吸附动力学,以确定树脂分离纯化淫羊藿EF5黄酮的最佳吸附性能;采用HPLC法,以淫羊藿EF5黄酮中五种黄酮单体的洗脱率为指标,考察洗脱液浓度和洗脱液用量等参数,确定淫羊藿EF5黄酮的最佳洗脱参数。结果:AB-8大孔吸附树脂对淫羊藿总黄酮的吸附容量以湿树脂计为(58.37±2.36)mg·g-1,解吸附率为(86.77±2.32)%,最佳吸附时间为180min,最佳洗脱液为60%乙醇,最佳洗脱液用量为5BV,纯化后真空干燥所得棕褐色淫羊藿EF5黄酮粉末中朝藿定A、朝藿定B、朝藿定C、淫羊藿苷和宝藿苷I的含量分别为3.51%、4.87%、1.22%、33.05%、1.36%,淫羊藿EF5黄酮纯度为44%。结论:AB-8大孔吸附树脂分离纯化得到的淫羊藿EF5黄酮的纯度较高,适合工业生产。

长江上游农业源溪流雨季中N_2O间接排放特征

农业源溪流与农田生态系统有着紧密的水文连接,其会随着农业非点源氮(N)污染的加剧而成为重要的N汇和氧化亚氮(N_2O)间接排放源.本研究采用静态暗箱-气相色谱法于2015年6~9月(所研究区域的雨季)原位测定了长江上游紫色土丘陵区农业源溪流的N_2O间接排放通量.结果表明,农业源溪流雨季中N_2O平均排放通量为12. 8μg·(m^2·h)^(-1),接近其所在区域内同季节农田的N_2O直接排放水平,是重要的农业N_2O间接排放源.该农业源溪流中N_2O间接排放系数值(EF5r=0. 01%)远低于IPCC的建议值(0. 25%)和重新计算的全球平均值(0. 20%),然而,全球EF5r的现有数据量仍十分有限、且有较大的空间差异,应加强对此类N_2O间接排放的研究,从而进一步修正EF5r的精度、减少N_2O间接排放估算的误差.本研究的N_2O间接排放通量与水中NO-3-N浓度正相关,反硝化是N_2O的主要产生过程.雨季中较强的降雨(如连续降雨日内降雨> 9 mm)可促进溪流中NO-3-N浓度在雨后短期内急剧升高,进而激发水中N_2O间接排放通量的明显增加.