急性T细胞白血病细胞变异型sil-tal1融合转录本和基因组DNA断裂点

本研究探究1例儿童急性T淋巴细胞白血病（T-ALL）的变异型sil-tal1融合转录本的序列。将PCR扩增产物克隆入质粒载体并测序,针对变异部分序列设计引物,对基因组DNA进行PCR扩增及序列比对。结果表明,在cDNA水平发现4种不同的融合转录本,分别保留了sil基因的部分外显子或内含子序列,并存在插入和删除现象。经分析白血病细胞的基因组DNA序列,发现了一种新的sil-tal1重组,其sil基因的断裂点在DNA水平上与文献报道不同。结论：此例患儿白血病细胞的tal1基因发生了新型重组,并表达经典型的和至少3种变异型的融合转录本,此现象可能是由于白血病细胞转录剪接机制异常所致。     

ADAR1同工型基因在小鼠急性T淋巴细胞白血病模型中的表达

本研究探讨RNA编辑酶ADAR1的2种同工型P110和P150在小鼠白血病发展中的表达变化规律。采用Notch1过表达小鼠急性T淋巴细胞白血病移植模型,在发病不同阶段分离骨髓单个核细胞,并在发病晚期用流式细胞术分选CD45.2+GFP+白血病细胞,用实时定量PCR方法检测ADAR1的表达变化。结果表明:对照组和白血病组小鼠骨髓细胞均表达ADAR1的2种同工型P110和P150mRNA;Notch1过表达导致的小鼠白血病发展过程中2种同工型的表达水平变化不同;随着白血病的发展,P110的表达水平逐渐升高,而P150表达水平逐渐降低,在移植后的第14天降至对照组的1/4。分选后的CD45.2+GFP+白血病细胞高表达P110而低表达P150。结论 :ADAR1的亚型P110和P150mRNA在小鼠白血病中的表达变化规律存在差异,提示二者介导的RNA编辑可能在白血病发展中发挥不同作用。     

肾透明细胞癌NOTCH1与JAG1的表达及意义

目的：探讨肾透明细胞癌跨膜受体蛋白（NOTCH1）与人类Jagged1基因（JAG1）的表达及意义。方法：应用免疫组化染色法比较肾透明细胞癌（n=129）及正常肾组织（n=33）中NOTCH1和JAG1蛋白的表达差异,并分析两者的表达与肿瘤临床病理参数的相关性。结果：肾透明细胞癌NOTCH1、JAG1阳性表达率高于正常肾组织（分别为95.3%比36.4%,P〈0.05;93.0%比42.4%,P〈0.05）;随着肾癌的病理分级、临床分期的增高和肿瘤的增大,NOTCH1和JAG1的表达水平均增高。复发组NOTCH1和JAG1蛋白的表达均高于未复发组,差异有统计学意义（P〈0.05）。结论：肾透明细胞癌NOTCH1和JAG1表达均高于正常肾组织,且与肿瘤分级、分期及肿瘤大小有关。两者对临床预后判断可能具有一定价值。     

NOTCH1在急性T淋巴细胞白血病中的作用及研究进展

急性T淋巴细胞白血病(T-ALL)是一组异质性极强的血液系统恶性肿瘤,在儿童和成人ALL中分别占10%~15%和20%~25%[1]。成人T-ALL由于原发化疗耐药以及早期复发等原因致预后不良,5年无事件生存(EFS)率仅为20%~50%[1]。目前对T-ALL发病机制的相关研究还很欠缺,同时缺少大样本的临床试验,缺乏有效的靶向药物和免疫治疗策略,导致T-ALL的基础和临床研究进展受限。值得注意的是,在60%以上的T-ALL患者中鉴定出NOTCH1基因功能获得性突变,导致非配体依赖性和持续激活的NOTCH1受体信号转导,为T-ALL的治疗干预提供了新思路[2]。迄今为止,NOTCH1是T-ALL基础研究中最为热门的癌基因之一。本文将重点对NOTCH1在T-ALL发病中的作用和最新研究进展作一综述,并对新型NOTCH1靶向治疗在临床上的应用前景进行了展望。     

成人T细胞急性淋巴细胞白血病中NOTCH1突变的特征研究

本研究旨在阐明NOTCH1突变在成人T细胞急性淋巴细胞白血病（T-ALL）中的特征及临床意义。通过对42例成人T-ALL患者外显子（exon）26／异二聚体N末端（HD-N）、exon27／异二聚体c末端（HD-C）、exon28和exon34／脯氨酸-谷氨酸-丝氨酸-苏氨酸（PEST）区域进行扩增、克隆和测序,研究NOTCH1突变的发生率、突变位点和类型、突变与临床和实验室指标的相关性及其预后意义。结果显示,本组成人T-ALL中NOTCH1突变率66．7％（28／42）,共发现45种NOTCH1突变,最多见于HD-N（48．9％,22／45）和PEST（40．0％,18／45）;HD-N结构域突变最多位于氨基酸位点1575（L1575P）（25．O％,7／28）,PEST结构域突变最多位于氨基酸位点2443（14．3％,4／28）;初诊时白细胞计数大于10×10^9／L者NOTCH1突变组显著高于无突变组（91．7％vs 54．5％,P=0．021）;骨髓原始及幼稚淋巴细胞比例超过50％者突变组显著高于无突变组（95．8％vs 57．1％,P=0．006）;流式免疫表型CDl0阳性表达率突变组显著高于无突变组（51．9％vs0％,P=0．006））,CD15和CD11b阳性表达率突变组显著低于无突变组（分别为5．3％vs 42．9％,P=0．047和0％vs57．1％,P=0．002）。结论：成人T-ALL的NOTCH1突变具有不同于儿童的突变特征和预后意义,而且中国成人T-ALL的NOCH1突变与西方国家相比可能存在差异。     

JAGGED1/NOTCH3 activation promotes aortic hypermuscularization and stenosis in elastin deficiency

Obstructive arterial diseases, including supravalvular aortic stenosis (SVAS), atherosclerosis, and restenosis, share 2 important features: an abnormal or disrupted elastic lamellae structure and excessive smooth muscle cells (SMCs). However, the relationship between these pathological features is poorly delineated. SVAS is caused by heterozygous loss-of-function, hypomorphic, or deletion mutations in the elastin gene (ELN), and SVAS patients and elastin-mutant mice display increased arterial wall cellularity and luminal obstructions. Pharmacological treatments for SVAS are lacking, as the underlying pathobiology is inadequately defined. Herein, using human aortic vascular cells, mouse models, and aortic samples and SMCs derived from induced pluripotent stem cells of ELN-deficient patients, we demonstrated that elastin insufficiency induced epigenetic changes, upregulating the NOTCH pathway in SMCs. Specifically, reduced elastin increased levels of γ-secretase, activated NOTCH3 intracellular domain, and downstream genes. Notch3 deletion or pharmacological inhibition of γ-secretase attenuated aortic hypermuscularization and stenosis in Eln^–/– mutants. Eln^–/– mice expressed higher levels of NOTCH ligand JAGGED1 (JAG1) in aortic SMCs and endothelial cells (ECs). Finally, Jag1 deletion in SMCs, but not ECs, mitigated the hypermuscular and stenotic phenotype in the aorta of Eln^–/– mice. Our findings reveal that NOTCH3 pathway upregulation induced pathological aortic SMC accumulation during elastin insufficiency and provide potential therapeutic targets for SVAS.     

Hypercoagulability in cirrhosis: causes and consequences1

Summary. Decreased levels of most coagulation factors and thrombocytopenia are the main haemostatic abnormalities of cirrhosis. As a consequence, this condition was, until recently, considered as the prototype acquired coagulopathy responsible for bleeding. However, recent evidence suggests that it should, rather, be regarded as a condition associated with normal or even increased thrombin generation. The bleeding events that occur in these patients should, therefore, be explained by the superimposed conditions that frequently occur in this setting. Due to elevated levels of factor VIII (procoagulant driver) in combination with decreased protein C (anticoagulant driver), which are typically found in patients with cirrhosis, a procoagulant imbalance, defined as a partial resistance to the in vitro anticoagulant action of thrombomodulin, can be demonstrated. Whether this in vitro hypercoagulability is truly representative of what occurs in vivo remains to be established. However, the hypothesis that it may have clinical consequences is attractive and deserves attention. The possible consequences that we discuss herein include whether (i) cirrhosis is a condition associated with increased risk of venous thromboembolism or portal vein thrombosis; (ii) the hypercoagulability associated with cirrhosis has any other role outside coagulation (i.e. progression of liver fibrosis); and (iii) anticoagulation should be used in cirrhosis. Although apparently provocative, considering anticoagulation as a therapeutic option in patients with cirrhosis is now supported by a rationale of increasing strength. There may be subgroups of patients who benefit from anticoagulation to treat or prevent thrombosis and to slow hepatic fibrosis. Clinical studies are warranted to explore these therapeutic options.     

Percutaneous thin needle biopsy of malignant and nonmalignant thoracic lesions

An analysis of 1,454 percutaneous thin needle biopsies (PTNB) performed in 1,061 patients in the years 1976-1987 disclosed the sensitivity for the detection of malignancy 93.7%, specificity 95.8%, and accuracy 93.9%. The most commonly encountered indication for PTNB was a solitary lung lesion (56% of 1,061 patients), with a rate of true positive cytologic findings 93.4% of patients with proved malignant tumours. Indications for PTNB included pulmonary opacities of or without recognizable segmental distribution, enlargement of mediastinum or hilus, lesions of the pleura or chest wall, and cavitary lesions, with results not significantly worse than in circumscribed peripheral lesions. Pneumothorax occurred in 18%, hemoptysis in 1.9%, other minor complications very rarely. PTNB appears to be a safe, reliable, and accurate technique for diagnosing chest lesions with various types of roentgenographic image.     

Analysis of the chronic lymphocytic leukemia coding genome: role of NOTCH1 mutational activation

The pathogenesis of chronic lymphocytic leukemia (CLL), the most common leukemia in adults, is still largely unknown. The full spectrum of genetic lesions that are present in the CLL genome, and therefore the number and identity of dysregulated cellular pathways, have not been identified. By combining next-generation sequencing and copy number analysis, we show here that the typical CLL coding genome contains <20 clonally represented gene alterations/case, including predominantly nonsilent mutations, and fewer copy number aberrations. These analyses led to the discovery of several genes not previously known to be altered in CLL. Although most of these genes were affected at low frequency in an expanded CLL screening cohort, mutational activation of NOTCH1, observed in 8.3% of CLL at diagnosis, was detected at significantly higher frequency during disease progression toward Richter transformation (31.0%), as well as in chemorefractory CLL (20.8%). Consistent with the association of NOTCH1 mutations with clinically aggressive forms of the disease, NOTCH1 activation at CLL diagnosis emerged as an independent predictor of poor survival. These results provide initial data on the complexity of the CLL coding genome and identify a dysregulated pathway of diagnostic and therapeutic relevance.     

急性T细胞白血病细胞变异型sil-tall融合转录本和基因组DNA断裂点

本研究探究1例儿童急性T淋巴细胞白血病(T-ALL)的变异型sil-tal1融合转录本的序列。将PCR扩增产物克隆入质粒载体并测序,针对变异部分序列设计引物,对基因组DNA进行PCR扩增及序列比对。结果表明,在cDNA水平发现4种不同的融合转录本,分别保留了sil基因的部分外显子或内含子序列,并存在插入和删除现象。经分析白血病细胞的基因组DNA序列,发现了一种新的sil-tal1重组,其sil基因的断裂点在DNA水平上与文献报道不同。结论:此例患儿白血病细胞的tal1基因发生了新型重组,并表达经典型的和至少3种变异型的融合转录本,此现象可能是由于白血病细胞转录剪接机制异常所致。     

High-level IGF1R expression is required for leukemia-initiating cell activity in T-ALL and is supported by Notch signaling

T cell acute lymphoblastic leukemia (T-ALL) is an aggressive cancer of immature T cells that often shows aberrant activation of Notch1 and PI3K-Akt pathways. Although mutations that activate PI3K-Akt signaling have previously been identified, the relative contribution of growth factor-dependent activation is unclear. We show here that pharmacologic inhibition or genetic deletion of insulin-like growth factor 1 receptor (IGF1R) blocks the growth and viability of T-ALL cells, whereas moderate diminution of IGF1R signaling compromises leukemia-initiating cell (LIC) activity as defined by transplantability in syngeneic/congenic secondary recipients. Furthermore, IGF1R is a Notch1 target, and Notch1 signaling is required to maintain IGF1R expression at high levels in T-ALL cells. These findings suggest effects of Notch on LIC activity may be mediated in part by enhancing the responsiveness of T-ALL cells to ambient growth factors, and provide strong rationale for use of IGF1R inhibitors to improve initial response to therapy and to achieve long-term cure of patients with T-ALL.     

Shifting ecologies of malignant and nonmalignant cells following BRAF inhibition

Clinical vignette: A 49-year-old man with stage IV BRAF^V600E-driven melanoma was initiated on twice-daily 960 mg of vemurafenib for treatment of progressive and recurrent subcutaneous metastatic disease of the left lower extremity. The patient’s melanoma responded well to targeted BRAF inhibition. At treatment onset, hematologic parameters were all within normal limits; however, within three months of initiating therapy, wbc were found to be elevated (to 20 K) with sustained lymphocytosis of mature phenotype. Immunophenotypic analysis was consistent with chronic lymphocytic leukemia (CLL), and FISH results revealed presence of the CLL-associated deletion in chromosome 13q14 as well as in 2p33. Vemurafenib was withdrawn after approximately one year of therapy, and subsequently, his peripheral lymphocytosis resolved and CLL regressed. Nevertheless, a monoclonal B cell population persisted even 732 days after discontinuation of vemurafenib.In this issue, Yaktapour et al. describe a patient with metastatic melanoma harboring the BRAF^V600E mutation who, upon treatment with the BRAF inhibitor vemurafenib, developed a sustained lymphocytosis that was ultimately diagnosed as del13q14 chronic lymphocytic leukemia (CLL) without mutations in IGHV. Notably, Yaktapour and colleagues demonstrate that SYK-mediated B cell receptor (BCR) signaling in CLL in the presence of drug-bound BRAF is a putative driver of the paradoxical MEK/ERK activation that has been occasionally observed in response to BRAF inhibition (1).     

Bafilomycin A1 and intracellular multiplication of Legionella pneumophila.

Multiplication of Legionella pneumophila in HeLa cells was found to be inhibited by noncytotoxic concentrations of bafilomycin A1, with blockage of bacterial growth at a concentration 15.6 nM. The inhibiting action was evident only when the antibiotic was present during the initial phase of intracellular multiplication, i.e., during the formation of the phagosome, whereas the addition of the drug did not affect microorganisms already actively multiplying within the phagosome.     

Misplacing V1 and V2 can have clinical consequences

The precordial electrocardiogram (ECG) leads V1 and V2 are often misplaced. Such misplacement usually involves placing these leads too high on the chest. The resulting ECG may generate erroneous ECG patterns: e.g. incomplete right bundle branch block, anterior T wave inversion, septal Q waves, ST-segment elevation. These features may falsely suggest acute or old cardiac ischemia, pulmonary embolism, or a type-2 Brugada pattern. On rare occasion, conversely, high placement of V1 and V2 may reveal a true type-1 Brugada pattern. The emergency clinician needs to be aware of the possibility of lead misplacement, and should know how to suspect it based on unusual P wave morphology in V1 and V2.     

Neointima formation and thrombosis after vascular injury in transgenic mice overexpressing plasminogen activator inhibitor-1 (PAI-1)

Summary.  The controversial role of plasminogen activator inhibitor-1 (PAI-1) in neointima formation and restenosis was studied with the use of a vascular injury model in transgenic mice overexpressing murine PAI-1 (PAI-1 Tg) and in wild-type (WT) controls. Despite the high circulating PAI-1 levels in the PAI-1 Tg mice (52 ± 9.8 ng mL⁻¹ vs. 0.76 ± 0.17 ng mL⁻¹ in WT mice), no significant fibrin deposition was observed in non-injured femoral arteries of 8- to 12-week-old mice. Two weeks after severe electric injury, extensive and comparable fibrin deposition was observed in both genotypes, despite a significantly reduced in situ fibrinolytic activity in arterial sections of the PAI-1 Tg mice. The neointimal and medial areas were similar in WT and PAI-1 Tg mice, resulting in comparable intima/media ratios (e.g. 0.94 ± 0.25 and 1.04 ± 0.17 at the center of the injury). Nuclear cell counts in cross-sectional areas of the neointima of the injured region were also comparable in arteries from WT and PAI-1 Tg mice (224 ± 63, 233 ± 20), and the distribution pattern of α-actin-positive smooth muscle cells was similar. These findings indicate that in a vascular injury model that induces extensive and persistent fibrin deposition in femoral arteries of mice, overexpression of PAI-1 does not affect neointima formation.     

人源性Notch-1胞内段腺病毒载体构建及鉴定

目的:构建携带人Notch-1胞内区基因的腺病毒栽体(Ad-GFP-NICD),观察其在真核细胞中的表达.方法:通过PCR从pIRES2-EGFP-NICD质粒中扩增目的片段Notch-1胞内区,定向克隆至穿梭质粒栽体pShuttle-CMV-EGFP中,经酶切及测序鉴定后,将Notch-1胞内区定向克隆至重组腺病毒骨架载体pAdxsi,构建携带人Notch-1胞内区基因表达盒及绿色荧光蛋白的重组腺病毒栽体(pAdxsi-GFP-NICD).酶切鉴定正确后,转染人胚肾细胞系293细胞,进行重组腺病毒的包装,生产及纯化,半数组织感染量法测定病毒滴度.用重组腺病毒转染人脐静脉内皮细胞,荧光显微镜下观察细胞绿色荧光蛋白的表达,并通过PCR扩增观察细胞Notch-1胞内区的表达.结果:成功构建了携带人Notch-1胞内区的重组腺病毒,纯化后病毒滴度达1.6×1010 pfu/mL.腺病毒载体转染人脐静脉内皮细胞后24 h在荧光显微镜下即可观察到绿色荧光蛋白,48 h更为强烈,PCR扩增证实细胞表达Notch-1胞内区.结论:成功构建了携带Notch-1胞内区的重组腺病毒载体,为进一步研究Notch信号通路促进动脉形成的机制研究奠定了实验基础.     

Suppression of macrophage oxidative metabolism by products of malignant and nonmalignant cells

Each of 11 tumors tested produced a factor that markedly suppressed the ability of macrophages to release H2O2 or O.2- in response to phorbol myristate acetate or zymosan. Four of seven normal cell types produced a similar activity, which was 3.5-7 times lower in titer than that in tumor cell-conditioned medium (TCM), and which was much more rapidly reversible in its effects. TCM caused 50% inhibition of H2O2 release when it was present in the medium for 48 h at a concentration of 13%, or when 100% TCM was present in the medium for 18 h. The H2O2-releasing capacity of macrophages incubated in TCM only returned to control levels by 6 d after its removal. TCM prevented augmentation of H2O2- releasing capacity by lymphokines. The titer of suppressive activity in TCM depended on both the concentration of tumor cells and the duration of their incubation. TCM did not augment the activity of catalase, myeloperoxidase, glutathione peroxidase, or glutathione reductase or the content of glutathione within macrophages, suggesting that decreased synthesis rather than increased catabolism was responsible for reduced secretion of H2O2. Suppression of the release of H2O2 or O.2- by TCM appeared to be a relatively specific effect, in that TCM increased macrophage spreading and adherence to glass while exerting little influence on rates of phagocytosis, synthesis of protein, or secretion of lysozyme, plasminogen activator, or arachidonic acid and its metabolites. Thus, tumor cells and some normal cells can secrete a factor that selectively deactivates macrophage oxidative metabolism.