A simple bone cyst (SBC) is a benign bone lesion of unknown etiology. It can be differentiated from an aneurysmal bone cyst (ABC) by radiologic and histopathologic features, as well as by the absence of fusions of the USP6 gene characteristic of an ABC. In an attempt to differentiate between ABC and SBC in a recurrent bone cyst, we performed targeted RNA sequencing and found an EWSR1-NFATC2 fusion and no fusion of the USP6 gene. We subsequently analyzed additional 10 cysts, consistent with SBCs after radiologic-pathologic correlation, for the presence of an NFATC2 gene fusion, by targeted RNA sequencing, reverse-transcription polymerase chain reaction (RT-PCR) and Sanger sequencing, and fluorescent in situ hybridization. Targeted RNA sequencing showed a FUS-NFATC2 fusion in 4 of 11 SBCs and an EWSR1-NFATC2 fusion in 2 of 11 SBCs. No fusion was identified in 3 SBCs and the analysis was not successful in 2 SBCs because of the low quantity or poor quality of isolated RNA. All the 6 fusions detected by targeted RNA sequencing were confirmed by RT-PCR and Sanger sequencing, and 5 of the 6 fusions by fluorescent in situ hybridization. An additional FUS-NFATC2 fusion was identified by RT-PCR, Sanger sequencing, and fluorescent in situ hybridization in 1 of the 3 cases negative for fusions by targeted RNA sequencing. At least a large subset of SBCs represents cystic neoplasms characterized by FUS-NFATC2 or EWSR1-NFATC2 fusions, which also define a group of distinct, rare “Ewing-like” sarcomas that predominantly arise in long bones. Our results provide additional evidence of the existence of benign lesions with FUS-NFATC2 or EWSR1-NFATC2 fusions. Although they can recur locally in a nondestructive manner, their clinical course and possible relation to sarcoma with EWSR1-NFATC2 or FUS-NFATC2 fusion remains to be elucidated.

BackgroundIdentifying the early genetic drivers can help diagnose glioma tumours in their early stages, before becoming malignant. However, there is emerging evidence that disturbance of epigenetic mechanisms also contributes to cell’s malignant transformation and cancer progression. Long non-coding RNAs are one of key epigenetic modulators of signalling pathways, since gene expression regulation is one of their canonical mechanisms. The aim of our study was to search new gliomagenesis-specific candidate lncRNAs involved in epigenetic regulation.Patients and methodsWe used a microarray approach to detect expression profiles of epigenetically involved lncRNAs on a set of 12 glioma samples, and selected LOC285758 for further qPCR expression validation on 157 glioma samples of different subtypes. To establish if change in expression is a consequence of epigenetic alterations we determined methylation status of lncRNA’s promoter using MS-HRM. Additionally, we used the MLPA analysis for determining the status of known glioma biomarkers and used them for association analyses.ResultsIn all glioma subtypes levels of LOC285758 were significantly higher in comparison to normal brain reference RNA, and expression was inversely associated with promoter methylation. Expression substantially differs between astrocytoma and oligodendroglioma, and is elevated in higher WHO grades, which also showed loss of methylation.ConclusionsOur study revealed that lncRNA LOC285758 changed expression in glioma is methylation-dependent and methylation correlates with WHO malignancy grade. Methylation is also distinctive between astrocytoma I-III and other glioma subtypes and may thus serve as an additional biomarker in glioma diagnosis.

Glioblastoma is the most common and malignant brain malignancy worldwide, with a 10-year survival of only 0.7%. Aggressive multimodal treatment is not enough to increase life expectancy and provide good quality of life for glioblastoma patients. In addition, despite decades of research, there are no established biomarkers for early disease diagnosis and monitoring of patient response to treatment. High throughput sequencing technologies allow for the identification of unique molecules from large clinically annotated datasets. Thus, the aim of our study was to identify significant molecular changes between short- and long-term glioblastoma survivors by transcriptome RNA sequencing profiling, followed by differential pathway-activation-level analysis. We used data from the publicly available repositories The Cancer Genome Atlas (TCGA; number of annotated cases = 135) and Chinese Glioma Genome Atlas (CGGA; number of annotated cases = 218), and experimental clinically annotated glioblastoma tissue samples from the Institute of Pathology, Faculty of Medicine in Ljubljana corresponding to 2–58 months overall survival (n = 16). We found one differential gene for long noncoding RNA CRNDE whose overexpression showed correlation to poor patient OS. Moreover, we identified overlapping sets of congruently regulated differential genes involved in cell growth, division, and migration, structure and dynamics of extracellular matrix, DNA methylation, and regulation through noncoding RNAs. Gene ontology analysis can provide additional information about the function of protein- and nonprotein-coding genes of interest and the processes in which they are involved. In the future, this can shape the design of more targeted therapeutic approaches.

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The aggressive nature of malignant gliomas and their genetic and clinical heterogeneity present a major challenge in their diagnosis and treatment. Development of targeted therapy brought attention on detecting novel gene fusions, since they represent promising therapeutic targets (eg, TRK inhibitors in NTRK fusion‐positive tumors). Using targeted next‐generation sequencing, we prospectively analyzed 205 primary brain tumors and detected a novel PTPRZ1‐ETV1 fusion transcript in 11 of 191 (5.8%) gliomas, including nine glioblastomas, one anaplastic oligodendroglioma and one pilocytic astrocytoma. PTPRZ1‐ETV1 fusion was confirmed by RT‐PCR followed by Sanger sequencing, and in‐silico analysis predicted a potential driver role. The newly detected fusion consists of the PTPRZ1 promoter in frame with the highly conserved DNA‐binding domain of ETV1 transcription factor. The ETV1 and PTPRZ1 genes are known oncogenes, involved in processes of tumor development. ETV1 is a member of the ETS family of transcription factors, already known oncogenic drivers in Ewing sarcoma, prostate cancer and gastrointestinal stromal tumors, but not in gliomas. Its overexpression contributes to tumor growth and more aggressive tumor behavior. PTPRZ1 is already considered to be a tumor growth promoting oncogene in gliomas. In 8%–16% of gliomas, PTPRZ1 is fused to the MET oncogene, resulting in a PTPRZ1‐MET fusion, which is associated with poorer prognosis but is also a positive predictive biomarker for treatment with kinase inhibitors. In view of the oncogenic role that the two fusion partners, PTPRZ1 and ETV1, exhibit in other malignancies, PTPRZ1‐ETV1 fusion might present a novel potential therapeutic target in gliomas. Although histopathological examination of PTPRZ1‐ETV1 fusion‐positive gliomas did not reveal any specific or unique pathological features, and the follow‐up period was too short to assess prognostic value of the fusion, careful monitoring of patients and their response to therapy might provide additional insights into the prognostic and predictive value of this novel fusion.