Molecular and Morphologic Correlates of the Alternative Lengthening of Telomeres Phenotype in High‐Grade Astrocytomas

Recent studies suggest that the telomere maintenance mechanism known as alternative lengthening of telomeres (ALT) is relatively more common in specific glioma subsets and strongly associated with ATRX mutations. We retrospectively examined 116 high‐grade astrocytomas (32 pediatric glioblastomas, 65 adult glioblastomas, 19 anaplastic astrocytomas) with known ALT status using tissue microarrays to identify associations with molecular and phenotypic features. Immunohistochemistry was performed using antibodies against ATRX, DAXX, p53 and IDH1^R132H mutant protein. EGFR amplification was evaluated by fluorescence in situ hybridization (FISH). Almost half of fibrillary and gemistocytic astrocytomas (44%) demonstrated ALT. Conversely all gliosarcomas (n = 4), epithelioid (n = 2), giant cell (n = 2) and adult small cell astrocytomas (n = 7) were ALT negative. The ALT phenotype was positively correlated with the presence of round cells (P = 0.002), microcysts (P < 0.0002), IDH1 mutant protein (P < 0.0001), ATRX protein loss (P < 0.0001), strong P53 immunostaining (P < 0.0001) and absence of EGFR amplification (P = 0.004). There was no significant correlation with DAXX expression. We conclude that ALT represents a specific phenotype in high‐grade astrocytomas with distinctive pathologic and molecular features. Future studies are required to clarify the clinical and biological significance of ALT in high‐grade astrocytomas.     

Recurrent mutations of NOTCH genes in follicular lymphoma identify a distinctive subset of tumours

Follicular lymphoma (FL) is one of the most common malignant lymphomas. The t(14;18)(q32;q21) translocation is found in about 80% of cases and plays an important role in lymphomagenesis. However, the molecular mechanisms involved in the development and transformation of this lymphoma are not fully understood. Gain‐of‐function mutations of NOTCH1 or NOTCH2 have recently been reported in several B cell lymphoid neoplasms but the role of these mutations in FL is not known. In this study we investigated the mutational status of these genes in 112 FLs. NOTCH1 and NOTCH2 mutations were identified in five and two cases, respectively (total 7/112, 6.3%). All mutations predicted for truncated protein in the PEST domain and were identical to those identified in other B cell lymphoid neoplasms. NOTCH‐mutated FL cases were characterized by lower frequency of t(14;18) (14% versus 69%, p = 0.01), higher incidence of splenic involvement (71% versus 25%, p = 0.02) and female predominance (100% versus 55%, p = 0.04). A diffuse large B cell lymphoma (DLBCL) component was more frequently identified in NOTCH‐mutated FL than in wild‐type cases (57% versus 18%, p = 0.03). These results indicate that NOTCH mutations are uncommon in FL but may occur in a subset of cases with distinctive, characteristic, clinicopathological features. Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

VEGF165抑制HK2细胞上皮-间充质转化过程中NOTCH信号系统的变化

目的 探讨应用血管内皮生长因子（VEGF）干预肾小管上皮-间充质转化（EMT）过程中NOTCH信号系统的变化及其意义。方法 1.体外培养的人肾小管上皮细胞（HK2）分为转化生长因子-β1（TGF-β1,5μg/L）单独作用组（T组）、TGF-β1（5μg/L）与VEGF（100μg/L）共同作用组（T+V组）,RT-PCR 及Western blot方法检测不同作用时间点JAGGED-1、α-平滑肌肌动蛋白（α-SMA）的表达。2. TGF-β1与不同浓度VEGF165（0.1、1、10和100μg/L）共同作用细胞24h,激光共聚焦显微镜（CFMS）、RT- PCR及Western blot检测E-cadherin、α-SMA、JAGGED-1、NOTCH1表达。 结果 1.作用后24和48h,T+V组α-SMA和JAGGED-1蛋白表达均明显低于T组（P<0.05）。2.同TGF-β1单独作用组比较,VEGF165（100 μg/L）与TGF-β1共同作用组E-cadherin表达明显增强,α-SMA、 JAGGED-1及NOTCH1表达均明显降低（P<0.05）。结论 VEGF可抑制TGF-β1诱导HK2细胞发生EMT,并同时下调EMT过程中JAGGED-1、NOTCH1分子表达,提示该效应可能是VEGF抑制EMT的机制之一。     

Putative role of specific JAG1 gene exons in modulating clinical features in patients with leukoencephalopathy

The aim of this study was to investigate the possible role of JAG1 gene mutations in modulating clinical features in patients with CADASIL-like phenotype which resulted negative for NOTCH3 gene mutations. Sixty-six CADASIL-like patients without NOTCH3 gene mutations were investigated for 5 out of 26 exons of the JAG1 gene, whose mutations were implicated in central nervous system vascular abnormalities. PCR was performed with primers specific for exons 3, 4, 13, 23 and 24 comprising the intron-exon boundaries. Amplicons were then analyzed by denaturing high performance liquid chromatography (DHPLC). The exons showing a variant DHPLC profile were directly sequenced. The sequence of exons 3, 4 and 23 revealed the presence of four already described polymorphisms in JAG1. 1001C/T (g.16015 C>T) in exon 4 was found in 9 patients, IVS23+18delT (g.33147 delT) in 29 patients, IVS3-15T/C (g.15852 T>C) in 17 patients, IVS2-43C/T (g.10532 C>T) in 1 patient; both the polymorphism 1001C/T and IVS3-15T/C were found in 3 patients. No mutations were found. These data demonstrate absence of correlation between mutations in specific JAG1 gene exons and clinical features in patients with CADASIL-like phenotype.     

Expression of a lymphatic endothelial cell marker in benign and malignant vascular tumors

Tumors of endothelial cell origin are relatively common. Soft tissue tumors and numerous subtypes of benign and malignant vascular tumors have been described; the histogenesis of many of these tumors is uncertain, and distinguishing between benign and malignant vascular tumors, some of which express lymphatic endothelial cell markers, can be problematic. In the present study, immunophenotypic expression of a novel hyaluronan receptor (LYVE-1), which is expressed by endothelial cells of normal lymphatic vessels but not blood vessels, was determined in benign and malignant vascular tumors. It was found that, except in lymphangiomas, intramuscular hemangiomas, and Masson's hemangiomas, endothelial cells in benign blood vessel tumors (including capillary and cavernous hemangiomas, glomus tumors, pyogenic granulomas, and epithelioid hemangiomas) were negative for LYVE-1, and that all angiosarcomas and Kaposi's sarcomas were positive for LYVE-1. Expression of LYVE-1 and other lymphatic endothelial cell markers in relatively few vascular neoplasms has implications for the histogenesis of these lesions, and may prove useful in distinguishing angiosarcoma and Kaposi's sarcoma from most common benign vascular tumors.     

肝癌细胞系PLC/PRF/5中染色质重塑蛋白ATRX表达的调控作用

目的探讨肝癌细胞中地中海贫血伴精神发育迟滞综合征基因(ATRX)对基因表达的影响及其可能机制。方法利用CRISPR/Cas9技术敲除PLC/PRF/5细胞中的ATRX。全转录组测序技术(RNA-seq)检测ATRX敲除前后的基因表达水平,并用DESeq2软件得出差异表达基因。最后利用转座酶可及性核染色质区域分析技术(ATAC-seq)对差异基因的染色质可及性进行分析。结果分析得到2 754个差异表达基因,其中MUC16和CXCL8均在ATRX缺失后表达显著上调(P0.05),且两基因附近都存在升高的染色质可及性的区域。结论在肝癌细胞中,ATRX调控大量基因的表达,且可能直接参与了MUC16与CXCL8的抑制,为进一步研究ATRX在肝癌发生中的作用提供了新的线索。     

Variant ATRX Syndrome with Dysfunction of ATRX and MAGT1 Genes

A 0.8kb intronic duplication in MAGT1 and a single base pair deletion in the last exon of ATRX were identified using a chromosome X‐specific microarray and exome sequencing in a family with five males demonstrating intellectual disability (ID) and unusual skin findings (e.g., generalized pruritus). MAGT1 is an Mg²⁺ transporter previously associated with primary immunodeficiency and ID, whereas mutations in ATRX cause ATRX‐ID syndrome. In patient cells, the function of ATRX was demonstrated to be abnormal based on altered RNA/protein expression, hypomethylation of rDNA, and abnormal cytokinesis. Dysfunction of MAGT1 was reflected in reduced RNA/protein expression and Mg²⁺ influx. The mutation in ATRX most likely explains the ID, whereas MAGT1 disruption could be linked to abnormal skin findings, as normal magnesium homeostasis is necessary for skin health. This work supports observations that multiple mutations collectively contribute to the phenotypic variability of syndromic ID, and emphasizes the importance of correlating clinical phenotype with genomic and cell function analyses.     

Prognostic Significance of NOTCH1 and FBXW7 Mutations in Pediatric T-ALL

The NOTCH signaling pathway plays important role in the development of multicellular organisms, as it regulates cell proliferation, survival, and differentiation. In adults, it is essential for the T- or B-lymphocyte lineage commitment. NOTCH1 and FBXW7 mutations both lead the activation of the NOTCH1 pathway and are found in the majority of T-ALL patients. In this study, the mutation analysis of NOTCH1 and FBXW7 genes was performed in 87 pediatric T-ALLs who were treated on the ALL-BFM protocols. In 19 patients (22%), activating NOTCH1 mutations were observed either in the heterodimerization domain or in the PEST domain and 7 cases (10%) demonstrated FBXW7 mutations (2 cases had both NOTCH1 and FBXW7 mutations). We also analyzed the relationship of the mutation data between the clinical and biological data of the patients. NOTCH1 and FBXW7, NOTCH1 alone were found correlated with lower initial leucocyte counts which was independent from the sex and T- cell immunophenotype. However, NOTCH1 and FBXW7 mutations were not predictive of outcome in the overall cohort of pediatric T-ALLs.     

Immunohistochemical localization of CD31, NOTCH1 and JAGGED1 proteins in experimentally induced polycystic ovaries of immature rats

We analyzed histomorphometrical changes and blood vessel immunohistochemical staining of CD31, NOTCH1 and JAGGED1 in induced polycystic ovaries of immature female Wistar rats, as well as serum hormone levels. The rats were randomly divided into control (n=18) and treated (n=18) groups. Treated animals received intramuscularly testosteronenantat weekly (0.1 mg/g). Controls received the same amount of ricinus oil. Rats were weighed daily. Control and treated subgroups (6 rats per subgroup) were subsequently sacrificed after 21, 28 and 35 days of treatment. In ovaries of treated rats we found large cystic follicles, thick stromal tissue, many atretic preantral follicles, no ovulation and a thinner granulosa cell layer. CD31 stained blood vessels in the theca layer were reduced, with reduced JAGGED1 and NOTCH1 immunostaining. In controls, preantral and antral follicles were larger than in the treated group. Treated animals showed statistically significant lower progesterone and higher testosterone levels. They gained more weight than controls. Reduced immunostaining for NOTCH1 and JAGGED1 of reduced blood vessels of the theca layer was found in all stages of folliculogenesis with a distinct reduction in cystic and atretic follicles. Our results provide evidence of intrinsic abnormality during all stages of folliculogenesis in polycystic ovaries and this may result from crosstalk between circulating gonadotropins and follicular angiogenesis.     

The matricellular protein CCN3 regulates NOTCH1 signalling in chronic myeloid leukaemia

Deregulated NOTCH1 has been reported in lymphoid leukaemia, although its role in chronic myeloid leukaemia (CML) is not well established. We previously reported BCR‐ABL down‐regulation of a novel haematopoietic regulator, CCN3, in CML; CCN3 is a non‐canonical NOTCH1 ligand. This study characterizes the NOTCH1–CCN3 signalling axis in CML. In K562 cells, BCR‐ABL silencing reduced full‐length NOTCH1 (NOTCH1‐FL) and inhibited the cleavage of NOTCH1 intracellular domain (NOTCH1‐ICD), resulting in decreased expression of the NOTCH1 targets c‐MYC and HES1. K562 cells stably overexpressing CCN3 (K562/CCN3) or treated with recombinant CCN3 (rCCN3) showed a significant reduction in NOTCH1 signalling (> 50% reduction in NOTCH1‐ICD, p < 0.05). Gamma secretase inhibitor (GSI), which blocks NOTCH1 signalling, reduced K562/CCN3 colony formation but increased that of K562/control cells. GSI combined with either rCCN3 or imatinib reduced K562 colony formation with enhanced reduction of NOTCH1 signalling observed with combination treatments. We demonstrate an oncogenic role for NOTCH1 in CML and suggest that BCR‐ABL disruption of NOTCH1–CCN3 signalling contributes to the pathogenesis of CML. © 2013 The Authors. Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.     

Mutation analysis of K-ras-2 in liver angiosarcoma and adjacent nonneoplastic liver tissue from patients occupationally exposed to vinyl chloride

Vinyl chloride (VC) is a potent liver carcinogen that induces angiosarcomas in humans and animals. Recent evidence shows that liver tumors from patients with VC exposure may have a specific K-ras mutation pattern. This study was performed to determine the status of K-ras-2 in liver angiosarcomas (LAS) from workers occupationally exposed to VC. We examined the presence of K-ras-2 mutations in 15 LAS from patients with known exposure to VC (median exposure: 8,260 ppm [range 3,900- 21,000 ppm]]. In all cases, other risk factors for the development of LAS were excluded. Direct DNA sequencing after microdissection of the tumor cells was used for the analysis. Heterozygous mutations of K-ras-2 were detected in 8/15 LAS (53%). Five patients (33%) had a mutation of codon 12 and three of codon 13 (20%). The most common changes were G-->A transitions in five LAS which lead to the substitution of aspartic acid for glycine in the resulting p21 protein. In two patients (13%), mutations of the K-ras-2 gene were identified in the adjacent nonneoplastic liver tissue. These data indicate that VC induces a high frequency of G-->A transitions in human LAS. This mutation pattern is likely a consequence of VC-DNA-adduct formation.