Inactivation of CDK2 is synthetically lethal to MYCN over-expressing cancer cells

Two genes have a synthetically lethal relationship when the silencing or inhibiting of 1 gene is only lethal in the context of a mutation or activation of the second gene. This situation offers an attractive therapeutic strategy, as inhibition of such a gene will only trigger cell death in tumor cells with an activated second oncogene but spare normal cells without activation of the second oncogene. Here we present evidence that CDK2 is synthetically lethal to neuroblastoma cells with MYCN amplification and over-expression. Neuroblastomas are childhood tumors with an often lethal outcome. Twenty percent of the tumors have MYCN amplification, and these tumors are ultimately refractory to any therapy. Targeted silencing of CDK2 by 3 RNA interference techniques induced apoptosis in MYCN-amplified neuroblastoma cell lines, but not in MYCN single copy cells. Silencing of MYCN abrogated this apoptotic response in MYCN-amplified cells. Inversely, silencing of CDK2 in MYCN single copy cells did not trigger apoptosis, unless a MYCN transgene was activated. The MYCN induced apoptosis after CDK2 silencing was accompanied by nuclear stabilization of P53, and mRNA profiling showed up-regulation of P53 target genes. Silencing of P53 rescued the cells from MYCN-driven apoptosis. The synthetic lethality of CDK2 silencing in MYCN activated neuroblastoma cells can also be triggered by inhibition of CDK2 with a small molecule drug. Treatment of neuroblastoma cells with roscovitine, a CDK inhibitor, at clinically achievable concentrations induced MYCN-dependent apoptosis. The synthetically lethal relationship between CDK2 and MYCN indicates CDK2 inhibitors as potential MYCN-selective cancer therapeutics.     

Preserved pulmonary vasodilative properties of aerosolized brain natriuretic peptide

IntroductionInhalation of vasoactive substances is an effective treatment of pulmonary hypertension. The B-type natriuretic peptide (BNP) leads to relaxation of smooth muscle cells, caused by an increased formation of cyclic guanosine monophosphate (cGMP). The biologic activity of BNP using an inhalative approach has not been addressed.MethodsIn order to assess the vasorelaxing capacity of exogenous BNP in the isolated ventilated and buffer perfused rabbit lung model, a stable pulmonary vasoconstriction was established by either the application of endothelin-1 or the thromboxane A₂ mimetic U46619. This was followed by an intravascular or aerosol application of BNP. CGMP was measured in the recirculating buffer fluid using a radioimmunoassay technique.ResultsDuring a stable plateau of U46619 induced pulmonary vasoconstriction (mean pulmonary artery pressure, PAP 25.5 ± 0.23 mmHg), the intravascular administration of BNP induced a rapid vasodilation (mean PAP 18.13 ± 0.95 mmHg, p < 0.001). This vasodilation was dose dependent and was paralleled by a 6-fold increase of cGMP. When BNP was aerosolized, pulmonary vasoconstriction was also significantly alleviated in the U46619 model (mean PAP 22 ± 2.1 mmHg) and during endothelin-1 induced vasoconstriction (mean PAP 17.1 ± 2.47 mmHg). Correspondingly, inhalation caused a significant augmentation of cGMP levels was.ConclusionThe vasodilative capability of BNP as an indicator of the biologic activity of this peptide is preserved during its aerosolization. Presumably these vascular actions are caused at least in part by an increased availability of cGMP.     

Release pattern of N-terminal probrain natriuretic peptide after intra-aortic balloon pump counterpulsation: Insights into the effects of mechanical unloading in patients with acute decompensated heart failure

A 60-year-old man with dilated cardiomyopathy and severe decompensated heart failure was acutely managed with intra-aortic balloon pump (IABP) counterpulsation. The present report shows the release pattern of plasma natriuretic peptides after IABP therapy. Preliminary findings suggest that natriuretic peptide levels can be used to measure adequate ventricular unloading by IABP counterpulsation, and that a significant early decrease in natriuretic peptide levels after IABP therapy may potentially help identify future candidates for cardiac recovery after prolonged circulatory support.     

冰片及芒硝外敷联合柴芍承气汤内服对重症急性胰腺炎并发肠麻痹的疗效观察

[目的]观察冰片及芒硝外敷联合柴芍承气汤内服对重症急性胰腺炎（SAP）并发肠麻痹患者的治疗效果。[方法]102例SAP并发肠麻痹患者在西医治疗的基础上加用冰片及芒硝外敷,柴芍承气汤内服（治疗组）,并与单纯西医治疗的90例相对照（对照组）,观察2组治疗后肠麻痹及实验室指标恢复情况、并发症、中转手术率、死亡率及住院天数。[结果]治疗组较对照组腹痛、腹胀缓解时间,肠鸣音及排便恢复时间,白细胞、炎症递质指标恢复正常时间及住院天数明显缩短（P〈0．05）;肠麻痹恢复有效率高,并发症发生率及中转手术率低（P〈0．05）;死亡率有所下降,但无统计学意义;血、尿淀粉酶恢复时间2组比较P〉0．05。[结论]冰片及芒硝外敷,柴芍承气汤内服能有效缓解SAP患者的肠麻痹,从而防止SAP患者病情进一步重症化。     

新型抗结核多肽N22肽衍生物的稳定性和体外抑菌活性研究

目的研究多肽N22肽衍生物的稳定性以及体外抑菌活性,证实这种新型抗结核多肽的抑菌作用并且为进一步的药代动力学研究提供参考依据。方法通过高效液相色谱分析N22肽衍生物和异烟肼在37℃培养基中（PH7.2）0～6d的含量变化。采用试管二倍稀释法以及AlamarBlue法考察N22肽衍生物的体外抑菌活性。结果HPLC的实验结果表明N22肽衍生物稳定性较异烟肼差。体外抑菌实验证实N22肽衍生物对结核分枝杆菌有明显的抑制作用,最低抑菌浓度（MIC）为50μg/ml,小于异烟肼的最低抑菌浓度。同时该多肽对大肠杆菌也有抑制作用,其MIC为130μg/ml。结论N22肽衍生物在热、酸碱条件下不稳定、易降解,与对照药物异烟肼相比,N22肽衍生物体外抑菌效果较好、MIC较低,而且该多肽不仅对结核分枝杆菌有抑制作用,对大肠杆菌同样具有抑制作用。     

乙型肝炎病毒相关性肝细胞癌中分泌型卷曲相关蛋白基因甲基化分析

目的 研究HBV相关性肝细胞癌(HCC)中分泌型卷曲相关蛋白(SFRP)1、SFRP2基冈甲基化状态及其与肝细胞癌发牛发展的关系.方法 利用甲基化特异性聚合酶链反应(MSP)法检测45例肝细胞癌患者术中取得癌组织、癌旁组织及6例胆囊结石或肝脏血管瘤患者正常肝组织中SFRP1、SFRP2基因的甲基化状态.数据行X2检验、Fisher's 确切概率法统计分析.结果 在45例HCC患者中,癌组织和癌旁组织中SFRP1基因的甲基化率分别占62.2%和35.6%(X2=6.403,P＜0.05);SFRP2基因的甲基化率分别占51.1%和28.9%(X2=4.630,P＜0.05);6例正常肝组织均未检测到甲基化.癌组织中SFRPI与SFRP2基因甲基化在性别、年龄、HBV血清标志物、癌旁组织类型、有无转移和病理分级等因素之间差异均无统计学意义(P＞0.05),癌组织中SFRP1与SFRP2基因异常甲基化具有线性相关性(r=0.381,P=0.01).结论 SFRP1和SFRP2基因甲基化在HBV相关性HCC中是个频发事件,将来有可能作为一种预测HCC形成的分子生物学标志物.     

B-Type Natriuretic Peptides for the Evaluation of Exercise Intolerance

Background

Cardiopulmonary exercise testing is the method of choice for the differentiation of exercise intolerance. This study sought to assess the utility of B-type natriuretic peptide (BNP) and N-terminal-pro-B-type natriuretic peptide (NT-proBNP) for the identification of a cardiocirculatory exercise limitation.

Methods

In 162 patients undergoing cardiopulmonary exercise testing, rest and peak exercise BNP and NT-proBNP levels were measured. In 94 patients fulfilling criteria for appropriate effort and sufficient diagnostic certainty, the accuracy of BNP and NT-proBNP for the prediction of a cardiocirculatory limitation, as assessed based on clinical and exercise testing data, was determined.

Results

A cardiocirculatory limitation was identified in 27 (29%) patients. Median (interquartile range) resting BNP [162 (45-415) vs 39 (19-94) vs 24 (15-46) pg/mL; P <.001] and NT-proBNP [506 (129-1167) vs 77 (35-237) vs 34 (19-77) pg/mL; P <.001] were higher in patients with cardiocirculatory as compared with those with pulmonary limitation (n = 28) and those without cardiocirculatory or pulmonary limitation (n = 39). The area under the receiver operator characteristics curve for BNP and NT-proBNP to identify a cardiocirculatory limitation was 0.79 and 0.84, respectively (P = .15 for comparison of the curves). Sensitivity and specificity of the optimal BNP cutoff of 85 pg/mL were 63% and 84%, respectively. Sensitivity and specificity of the optimal NT-proBNP cutoff of 223 pg/mL were 74% and 85%, respectively. Peak exercise biomarkers were not more accurate than resting levels.

Conclusions

Among patients referred for cardiopulmonary exercise testing for evaluation of unexplained exercise intolerance, BNP and NT-proBNP were similarly useful to identify those with a cardiocirculatory limitation.     

Cell surface nucleolin antagonist causes endothelial cell apoptosis and normalization of tumor vasculature

Nucleolin is specifically transported to the surface of proliferating endothelial cells in vitro and in vivo. In contrast to its well defined functions in the nucleus and cytoplasm, the function of cell surface nucleolin is poorly defined. We have previously identified the nucleolin-binding antibody NCL3 that specifically binds to cell surface nucleolin on angiogenic blood vessels in vivo and is internalized into the cell. Here, we show that NCL3 inhibits endothelial tube formation in vitro as well as angiogenesis in the matrigel plaque assay and subcutaneous tumor models in vivo. Intriguingly, the specific targeting of proliferating endothelial cells by NCL3 in subcutaneous tumor models leads to the normalization of the tumor vasculature and as a result to an increase in tumor oxygenation. Treatment of endothelial cells with anti-nucleolin antibody NCL3 leads to a decrease of mRNA levels of the anti-apoptotic molecule Bcl-2 and as a consequence induces endothelial cell apoptosis as evidenced by PARP cleavage. These data reveal a novel mode of action for anti-angiogenic therapy and identify cell surface nucleolin as a novel target for combinatorial chemotherapy.