Reduced hydroxymethylation characterizes medulloblastoma while TET and IDH genes are differentially expressed within molecular subgroups.

INTRODUCTION: Medulloblastoma (MB) is an embryonal tumour that originates from genetic deregulation of cerebellar developmental pathways and is classified into 4 molecular subgroups: SHH, WNT, group 3, and group 4. Hydroxymethylation levels progressively increases during cerebellum development suggesting a possibility of deregulation in MB pathogenesis. The aim of this study was to investigate global hydroxymethylation levels and changes in TET and IDH gene expression in MB samples compared to control cerebellum samples. METHODS: The methods utilized were qRT-PCR for gene expression, dot-blot and immunohistochemistry for global hydroxymethylation levels and sequencing for the investigation of IDH mutations. RESULTS: Our results show that global hydroxymethylation level was decreased in MB, and low 5hmC level was associated with the presence of metastasis. TET1 expression levels were decreased in the WNT subgroup, while TET3 expression levels were decreased in the SHH subgroup. Reduced TET3 expression levels were associated with the presence of events such as relapse and death. Higher expression of IDH1 was observed in MB group 3 samples, whereas no mutations were detected in exon 4 of IDH1 and IDH2. CONCLUSION: These findings suggest that reduction of global hydroxymethylation levels, an epigenetic event, may be important for MB development and/or maintenance, representing a possible target in this tumour and indicating a possible interaction of TET and IDH genes with the developmental pathways specifically activated in the MB subgroups. These genes could be specific targets and markers for each subgroup.

MiRNA Dysregulation in Childhood Hematological Cancer.

For decades, cancer biology focused largely on the protein-encoding genes that have clear roles in tumor development or progression: cell-cycle control, apoptotic evasion, genome instability, drug resistance, or signaling pathways that stimulate growth, angiogenesis, or metastasis. MicroRNAs (miRNAs), however, represent one of the more abundant classes of cell modulators in multicellular organisms and largely contribute to regulating gene expression. Many of the ~2500 miRNAs discovered to date in humans regulate vital biological processes, and their aberrant expression results in pathological and malignant outcomes. In this review, we highlight what has been learned about the roles of miRNAs in some of the most common human pediatric leukemias and lymphomas, along with their value as diagnostic/prognostic factors.

TET2 Regulates the Neuroinflammatory Response in Microglia.

Epigenomic mechanisms regulate distinct aspects of the inflammatory response in immune cells. Despite the central role for microglia in neuroinflammation and neurodegeneration, little is known about their epigenomic regulation of the inflammatory response. Here, we show that Ten-eleven translocation 2 (TET2) methylcytosine dioxygenase expression is increased in microglia upon stimulation with various inflammogens through a NF-κB-dependent pathway. We found that TET2 regulates early gene transcriptional changes, leading to early metabolic alterations, as well as a later inflammatory response independently of its enzymatic activity. We further show that TET2 regulates the proinflammatory response in microglia of mice intraperitoneally injected with LPS. We observed that microglia associated with amyloid ß plaques expressed TET2 in brain tissue from individuals with Alzheimer's disease (AD) and in 5xFAD mice. Collectively, our findings show that TET2 plays an important role in the microglial inflammatory response and suggest TET2 as a potential target to combat neurodegenerative brain disorders.

TLE1 as an indicator of adverse prognosis in pediatric acute lymphoblastic leukemia.

PURPOSE: Acute lymphoblastic leukemia (ALL) is the most common type of cancer in children, and despite the high rate of cure (over 80%) it still has a big impact on morbidity and mortality. The Transducin-like enhancer of split 1 (TLE1), a transcriptional corepressor, has been described as dysregulated and recently emerged as a tumor marker in several cancer types, including hematologic malignancies. METHODS: In the present study TLE1 gene expression was evaluated by RT-qPCR. A total of 60 consecutive pathological ALL samples and 8 normal bone marrow samples were included. Associations between TLE1 levels and clinicopathological features were estimated using Mann-Whitney tests. RESULTS: TLE1 mRNA levels were significantly diminished in ALL samples when compared to normal counterparts (fold change -1.45, p-value 0.039). Lower TLE1 expression levels were associated with poorer prognostic features such as age at diagnosis (<1 or >9 years-old), absence of the Common Acute Lymphoblastic Leukemia Antigen (CALLA) and high white cell count. Considering immunophenotype, decreased expression of TLE1 was only evident for T-cell ALL, what was validated using gene expression profiling data available in public repositories. No associations with event or overall survival were observed. However, TLE1 expression was statistically different between patients who achieved complete clinical remission (CCR) from those that relapsed or died. CONCLUSION: These data are of particular interest and give support for a plausible role of TLE1 as a tumor suppressor in T-cell ALL. Moreover, the prognostic value of this corepressor may assist ALL treatment stratification and suggest the need of alternative regimens.