High Incidence of Activating TERT Promoter Mutations in Meningiomas Undergoing Malignant Progression

Meningiomas are common central nervous system tumors. The World Health Organization (WHO) defines three grades, predictive of the risk of recurrence. These tumors can relapse frequently and sometimes undergo malignant transformation. Maintenance of telomere length is a key process in malignant progression, and mutations in TERT promoter have recently been identified in various types of cancer. We sequenced the TERT promoter in 85 meningiomas from 73 patients. We found a high incidence of TERT promoter mutations in patients with meningiomas undergoing malignant histological progression (28%, n = 5/18 patients). In this subset of patients with histological progression, TERT promoter mutations were found in both the lowest and the highest grade tumors, and in both NF2‐mutated and nonmutated samples. In contrast, one mutation was identified in 35 meningiomas without recurrence or progression, belonging to various histological grades. This sample was an aggressive meningioma in a patient who died shortly after surgery. Interestingly, tumors showing relapse without histological progression were not mutated for TERT promoter (n = 20). Finally, TERT promoter mutations were associated with a marked increase in TERT expression. Thus, TERT promoter mutations are pivotal genetic alterations involved in malignant progression of meningiomas and could be used as a biomarker to identify meningiomas at risk of malignant transformation.     

Metastatic meningioma detected in pleural fluid

Meningiomas with both malignant cytologic features and clinical behavior are rare. A 39-yr-old man with recurrent meningioma developed a pleural effusion which, on cytologic examination, contained metastatic meningioma. The diagnosis was subsequently confirmed histologically and ultrastructurally. In conclusion, metastatic meningiomas can retain meningotheliomatous cytologic features which may allow a diagnosis to be made of clinically unanticipated tumor spread. Diagn. Cytopathol. 1998;18:453–457. © 1998 Wiley-Liss, Inc.     

TERT多表位疫苗的制备及其免疫原性初步研究

目的:制备端粒酶逆转录酶(TERT)的多表位(meTERT)肽疫苗和DNA疫苗,免疫小鼠,对其免疫原性进行初步研究。方法:用重叠延伸PCR将TERT的多个CD4+和CD8+T细胞表位串联连接,得meTERT的DNA片段;将该片段分别连接到真核表达载体pcDNA3.1及原核表达载体pGEX-4T中,制备DNA疫苗(PCT),并原核表达多表位肽疫苗(PCG);皮下/肌肉(50μg/100μg)免疫小鼠3次,取脾细胞,用ELISPOT法检测分泌IFN-γ和IL-4的细胞频率;用乳酸脱氢酶(LDH)释放法检测特异性脾细胞杀伤率(抗原刺激的SP2/0细胞为靶细胞)。结果:成功制备meTERT的PCT和PCG疫苗;动物实验表明:PCT+PCG联合免疫诱导的分泌IFN-γ的淋巴细胞数量显著高于其它各组(P0.01);另外,PCT+PCG诱导的分泌IFN-γ的淋巴细胞数显著高于分泌IL-4的数量;PCT+PCG联合免疫诱导了显著的脾细胞杀伤活性(67.8%)。结论:含多个CD4+和CD8+T细胞表位的meTERT的DNA疫苗PCT和多表位肽疫苗PCG联合免疫能够诱导强烈的Th1和CTL细胞免疫应答。     

The genetic landscape of anaplastic pleomorphic xanthoastrocytoma

Pleomorphic xanthoastrocytoma (PXA) is an astrocytic neoplasm that is typically well circumscribed and can have a relatively favorable prognosis. Tumor progression to anaplastic PXA (WHO grade III), however, is associated with a more aggressive biologic behavior and worse prognosis. The factors that drive anaplastic progression are largely unknown. We performed comprehensive genomic profiling on a set of 23 PXAs from 19 patients, including 15 with anaplastic PXA. Four patients had tumor tissue from multiple recurrences, including two with anaplastic progression. We find that PXAs are genetically defined by the combination of CDKN2A biallelic inactivation and RAF alterations that were present in all 19 cases, most commonly as CDKN2A homozygous deletion and BRAF p.V600E mutation but also occasionally BRAF or RAF1 fusions or other rearrangements. The third most commonly altered gene in anaplastic PXA was TERT, with 47% (7/15) harboring TERT alterations, either gene amplification (n = 2) or promoter hotspot mutation (n = 5). In tumor pairs analyzed before and after anaplastic progression, two had increased copy number alterations and one had TERT promoter mutation at recurrence. Less commonly altered genes included TP53, BCOR, BCORL1, ARID1A, ATRX, PTEN, and BCL6. All PXA in this cohort were IDH and histone H3 wildtype, and did not contain alterations in EGFR. Genetic profiling performed on six regions from the same tumor identified intratumoral genomic heterogeneity, likely reflecting clonal evolution during tumor progression. Overall, anaplastic PXA is characterized by the combination of CDKN2A biallelic inactivation and oncogenic RAF kinase signaling as well as a relatively small number of additional genetic alterations, with the most common being TERT amplification or promoter mutation. These data define a distinct molecular profile for PXA and suggest additional genetic alterations, including TERT, may be associated with anaplastic progression.     

Massively parallel sequencing of phyllodes tumours of the breast reveals actionable mutations,and TERT promoter hotspot mutations and TERT gene amplification as likely drivers of progression

Phyllodes tumours (PTs) are breast fibroepithelial lesions that are graded based on histological criteria as benign, borderline or malignant. PTs may recur locally. Borderline PTs and malignant PTs may metastasize to distant sites. Breast fibroepithelial lesions, including PTs and fibroadenomas, are characterized by recurrent MED12 exon 2 somatic mutations. We sought to define the repertoire of somatic genetic alterations in PTs and whether these may assist in the differential diagnosis of these lesions. We collected 100 fibroadenomas, 40 benign PTs, 14 borderline PTs and 22 malignant PTs; six, six and 13 benign, borderline and malignant PTs, respectively, and their matched normal tissue, were subjected to targeted massively parallel sequencing (MPS) using the MSK‐IMPACT sequencing assay. Recurrent MED12 mutations were found in 56% of PTs; in addition, mutations affecting cancer genes (eg TP53, RB1, SETD2 and EGFR) were exclusively detected in borderline and malignant PTs. We found a novel recurrent clonal hotspot mutation in the TERT promoter (?124 C>T) in 52% and TERT gene amplification in 4% of PTs. Laser capture microdissection revealed that these mutations were restricted to the mesenchymal component of PTs. Sequencing analysis of the entire cohort revealed that the frequency of TERT alterations increased from benign (18%) to borderline (57%) and to malignant PTs (68%; p < 0.01), and TERT alterations were associated with increased levels of TERT mRNA (p < 0.001). No TERT alterations were observed in fibroadenomas. An analysis of TERT promoter sequencing and gene amplification distinguished PTs from fibroadenomas with a sensitivity and a positive predictive value of 100% (CI 95.38–100%) and 100% (CI 85.86–100%), respectively, and a sensitivity and a negative predictive value of 39% (CI 28.65–51.36%) and 68% (CI 60.21–75.78%), respectively. Our results suggest that TERT alterations may drive the progression of PTs, and may assist in the differential diagnosis between PTs and fibroadenomas. Copyright © 2015 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

BRAF mutation,TERT promoter mutation,and HER2 amplification in sporadic or neurofibromatosis-related neurofibromas and malignant peripheral nerve sheath tumors: do these molecules have a signature in malignant transformation?

Peripheral nerve sheath tumors may occur sporadically or related to neurofibromatosis (NF). Unless the mechanisms of tumorigenesis in NF related malignant peripheral nerve sheath tumors (MPNST) are better understood, it remained unclear in sporadic cases. We aimed to investigate the genetic route for malignancy in both individuals with NF-1 and sporadic ones to open a way for targeted therapies in the future. We investigated the role of HER2 with Dual ISH DNA Probe Cocktail test, BRAF mutation (exon 15) and TERT promoter mutation frequency with Sanger sequencing method in respectively 25 sporadic neurofibromas, 25 NF-1 related neurofibromas and 25 MPNST cases from two institutes. Categorical data were analyzed and summarized as frequency and percentage. Statistical analysis was done with SPSS v.22 statistical package, and the statistical significance level was considered as 0.05. We identified TERT promoter mutation only in one sporadic MPNST (4%) and no BRAF mutation in any case. HER2 amplification is found in 10/25 (40%) MPNST cases. No mutations or gene amplification detected in neurofibromas (p < 0.001). MPNSTs are sarcomas with poor prognosis and limited treatment options. TERT promoter mutations and HER2 amplification may play a putative role in therapeutic purposes.     

Prevalence of HBV core promoter/precore/core mutations in Gambian chronic carriers.

One hundred forty-two precore/core sequences were obtained from Gambian chronic hepatitis B virus (HBV) carriers and the predominant variants defined. The two point mutations, from A to T and G to A at nt positions 1762 and 1764 in the basic core promoter region, were found in only 7/99 (7%) of the samples where this region was sequenced. These mutations were found in both HBeAg-positive and -negative patients. The precore stop-codon mutation at nt position 1896 was found in 14/51 (27%) of HBeAg-negative samples, which is a lower prevalence rate in comparison with other parts of the world with high carrier rates. In HBeAg-positive patients the core amino acid sequences were conserved, but after seroconversion to anti-HBe significantly more changes were apparent. Several of the amino acid substitutions found have been described previously been in wild-type viruses of other genotypes.