48 research outputs found
Biomolecular characterization of metastatic medulloblastoma and study of telomere lengthening control
No full textMedulloblastoma (MDB) is a malignant embryonic brain tumor and occurs typically in pediatric patients. Medulloblastoma cells can disseminate through the cerebrospinal fluid in the leptomeningeal space; approximately 30% of children present metastasis at the onset and no gold standard treatment has been defined for these patients. Genetic, epigenetic and molecular analyses identified four molecular subgroups (WNT, SHH, group 3 and group 4), associated with prognostic stratification of patients; however, previous works in literature included only small amount of metastatic cases, not analyzed independently from the non-metastatic counterpart. Furthermore, recent studies evidenced that mechanisms of telomeres elongation can be activated in pediatric brain tumours and telomeres maintenance was enriched in SHH and group 3 non-metastatic MDB; however, elongation of telomeres was not previously investigated in metastatic medulloblastomas.
Therefore, our aim is to characterize a series of 39 pediatric MDB, selected from a cohort of 60, with leptomeningeal dissemination at the onset, studying molecular features involved in malignancy, metastasis, telomeres elongation and senescence escape. We analyzed several biomarkers and we correlated results to outcome of patients, evaluating the prognostic relevance of molecular biomarkers and subgroups. Furthermore, we analyzed the activation of mechanisms involved in control of telomeres lengthening, in order to figure out if telomeres elongation could have a role in metastatic medulloblastomas.
We show that distribution of metastatic MDB into four molecular subgroups is highly similar to the distribution of non-metastatic cases, reflecting a high molecular heterogeneity; interestingly, our molecular subgrouping system defines high-risk (group SHH, 3 and 4) and standard-risk (group WNT and Not Classifiable) patients. Furthermore, we evidence that FSTL5 over-expression is associated exclusively with groups 3/4 and with poor outcome of patients, highlighting that FSTL5 can be used to better define molecular subgroups, prognosis and risk stratification of metastatic medulloblastomas.
In addition, we analyzed H3.3 and ATRX mutations, involved in activation of the Alternative Lengthening of Telomeres (ALT) pathway, and the mutation and methylation status of TERT promoter, involved in telomerase reactivation. We evidence that metastatic MDB activate elongation of telomeres both via telomerase (14%) and via ALT mechanism (27%), triggered by ATRX mutations; interestingly, ALT pathway is highly activated in our cohort compared to MDB previously analysed in literature (<5%), highlighting the differences between metastatic and non-metastatic tumors in control of telomeres elongation and senescence escape. Furthermore, metastatic MDB show a higher reactivation of telomerase compared to pHGG (0%), triggered by TERT promoter mutations in combination with hyper-methylation. Our findings suggest that immortalization of tumor cells in metastatic MDB is a common process to escape from senescence and characterizes all molecular subgroups.
In conclusion, our results contribute to improve the current characterization of pediatric patients with metastatic medulloblastoma; however, further studies will be necessary to increase the number of cases and to analyze, with statistical significance, the molecular subgroups, FSTL5 expression, and telomeres elongation, which could be used to “personalize” treatments or develop targeted therapies, reducing the side effects of the current therapeutic protocols
Mastering Microsoft Windows Server 2008 R2
No full textThe one book you absolutely need to get up and running with Windows Server 2008 R2. One of the world's leading Windows authorities and top-selling author Mark Minasi explores every nook and cranny of the latest version of Microsoft's flagship network operating system, Windows Server 2008 R2, giving you the most in-depth coverage in any book on the market.: Focuses on Windows Windows Server 2008 R2, the newest version of Microsoft's Windows' server line of operating system, and the ideal server for new Windows 7 clients; Author Mark Minasi is one of the world's leading Windows authorities and
Mastering Windows Server 2008 Networking Foundations
No full textFind in-depth coverage of general networking concepts and basic instruction on Windows Server 2008 installation and management including active directory, DNS, Windows storage, and TCP/IP and IPv4 networking basics in Mastering Windows Server 2008 Networking Foundations. One of three new books by best-selling author Mark Minasi, this guide explains what servers do, how basic networking works (IP basics and DNS/WINS basics), and the fundamentals of the under-the-hood technologies that support staff must understand. Learn how to install Windows Server 2008 and build a simple network, security c
Distribution and prognostic impact of molecular subgroups in a homogeneously treated series of metastatic medulloblastoma
No full textMedulloblastoma (MDB) is the most common malignant paediatric brain
tumor. Prognostic system based on clinical parameters and histopathological
variants is commonly used in clinical practice. Four different molecular subgroups
are recognized: WNT and SHH, having specific homonymous
pathwayalterations;Cand D, havingseveral genetic alterationsand associated
to a worse outcome, but the system has not been prospectively validated in
metastatic cohorts. Purpose of this studywasto evaluate distribution andprognostic
impact of the four molecular subgroups in 47 MDB metastatic at the
onset, homogenously treated in a single institution (Gandola et al, JCO
2009). Subgroup biomarkers were investigated by IHC, RT-PCR, mRNA sequencing,
FISH; results were correlated with patient outcomes by
Kaplan-Meier. We identify 11% WNT with nuclear b-catenin, 19% SHH,
26%groupCand15%group D;29%were unclassifiable (NC) having heterogeneous
biomarkers. MYC amplification was more frequent (32.5%) compared
to MYCN (2.7%). WNT and NC groups showed longer (not
significant) OSand PFS compared to SHH,Cand D. Furthermore, low expression
of FSTL5 was associated with good prognosis (OS rate 90%, PFS rate
100%), while FSTL5 higher expression correlate with worse outcome (OS
and PFS rate 66%); difference was statistically significant (p 1⁄4 0,05). We
have previously shown that histological variants maintain prognostic value
in metastatic MDB; on the opposite, molecular sub-grouping is inefficient to
allow a better risk stratification in our metastatic MDB cohort; furthermore,
FSTL5 gene expression might be used in metastatic MDB as prognostic
factor to better define patient outcome
Biomolecular Analysis of Pediatric Medulloblastoma and Prognostic Relevance of FSTL5 Expression: A Single-Center Study
No full textFSTL5 expression is a marker of Group C metastatic medulloblastomas
No full textINTRODUCTION: Medulloblastoma (MB) is the most commonmalignant
brain tumor in children. Four different molecular subgroups are recognized,
which differ in gene expression, genomic aberrations, histology, demographics
and survival:WNT and SHH groups, having specific mutations in the homonymous
pathway, and groups C and D having several genetic alternations
not specific to a single pathway. The gene for follistatin-like protein 5, FSTL5,
is overexpressed in nonSHH/nonWNT MBs poorly characterized. Highexpression
of FSTL5 is significantly associated with reduced event-free and
overall survival in non-WNT/non-SHHMBs. The major aim of this project is
to study the FSTL5 expression level in pediatric MBs with metastasis at the
onset. METHOD: We investigated the protein expression of biomarkers involved
in metastatic pathways by IHC and FSTL5 expression level by
RT-PCR in 26 metastatic MBs samples and correlated these data with the outcomes
by Kaplan-Meier statistic analysis. RESULTS: 83% of Group C MBs
showed high level of FSTL5 while none of these presented down-expression.
Low-expression level of FSTL5 was find in 60% of SHH MBs and none
showed over-expression. Kaplan-Meier test revealed that, in our cohort, highexpression
ofFSTL5didnot correlatewithworse outcomewhile lowexpression
of FSTL5 was associated with good prognosis and the co-presence of FSTL5
with other biomarkers correlated with poorer prognosis. CONCLUSION:
FSTL5 is a marker of Group C in medulloblastomas with metastasis at the
onset and the results highlighted decreased FSTL5 expression as a marker of
good prognosis. Group C MBs have characteristic molecular features that
confirm the poorest outcome also inMBs with metastasis at the onset
Brafv600e and Ctbn1 Mutational Study in Rathke's Cleft Cysts
No full textAim: Rathke's cleft cysts and craniopharyngiomas tipically involve sellar region and their histogenetic relationship
is still matter of debate. Clinical and histopathologic differentiation of cystic lesions from the sellar region, that is,
craniopharyngiomas (CPs) and Rathke cleft cysts (RCCs), is challenging and has great importance with respect to
variable clinical manifestation and adapted surgical treatment strategies in both entities. The recent acquisition that
adamantinomatous and papillary craniopharyngiomas bear distinct molecular alterations i.e., β-catenin (CTNNB1)
and BRAFv600 mutations respectively, has suggest to screen for such alteration a series of Rathke cyst to seek a
possible relation with one of the two craniopharyngioma type.
Methods: Seven Rathke's cleft cysts were analyzed for BRAF and CTNNB1 mutational status by sequencing and
immunohistochemistry. Radiological, clinical and histological features were performed.
Results: None of the 7 Rathke's cleft cysts harbor BRAFV600E mutation. No CTNNB1 mutation was found.
Radiological, clinical and histological re-evaluation of the cases confirmed the diagnosis of Rathke's cleft cysts.
Conclusion: BRAFV600E and CTNNB1 mutations appeared, as most reliable factor for the differentiation
between purely cystic CPs and RCCs, whereas tumor location, tumor size, and radiological parameter of the tumor
were less consistent parameters. This study again confirms that craniopharyngiomas (CPs) and Rathke cleft cysts
(RCCs), are associated with distinct pathogenic pathways
Case report of a pediatric medulloblastoma with concurrent MYC and MYCN subclonal amplification in distinct populations of neoplastic cells
No full text: Medulloblastomas (MDBs) are classified into molecular groups showing peculiar immunohistochemical and genetic features and distinct DNA methylation profile. Group 3 and group 4 MDBs have the worst prognosis; the former is treated with high-risk protocols and features MYC amplification, whereas the latter receives standard-risk protocols and harbors MYCN amplification. Herein, we report a unique case of MDB showing histological and immunohistochemical features consistent with non-SHH/non-WNT classic MDB, with both MYCN (30% of tumor cells) and MYC (5-10% tumor cells) amplification in distinct subclones of neoplastic cells at fluorescence in situ hybridization (FISH), characterized by specific patterns. In spite of MYC amplification in only a small percentage of tumor cells, this case had DNA methylation profile consistent with group 3, emphasizing the importance to test both MYC and MYCN amplifications at a single cell level using highly sensitive methods, such as FISH, for diagnostic and therapeutic purposes
MEDB-68. Analysis of telomeres length and Alternative Lengthening of Telomeres (ALT) in molecular subgroups of infant medulloblastoma
No full textWe investigated the association between the molecular profile and telomere length in a infant medulloblastoma (iMB) cohort, retrospectively studied. Activation of telomeres maintenance mechanisms was analyzed to determine whether the senescence escape triggered by telomere-elongation mechanisms could explain the aggressivity of some iMB belonging to the same molecular subgroup. Interestingly, several telomerase- and ALT-targeted therapies have recently been tested on pediatric cancers and might represent a promising strategy for the future treatment of aggressive telomerase- or ALT-positive iMB. We analyzed a cohort of 50 FFPE tissues from young MB patients (age ≤ 3); IHC, FISH, and an Illumina 850K methylation profile were used to identify molecular subgroups. Telomere length was measured using Telo-quantitative FISH, and image analysis was performed using TFL-Telo software. Three distinct telomere intensity categories (low (L), medium (M), and high (H)) were identified by comparing neoplastic- to endothelial-cell signals in each sample. ATRX loss and TERTp mutation/methylation were investigated using IHC and Sanger sequencing/methylation-specific PCR. SHH-MBs accounted for 59% of our cohort, while Group3/4-MBs accounted for 41%; no WNT-MBs were detected. ALT was found to be activated in 10% of iMBs and was not exclusive to any molecular subgroup, implying that it could be a potential mechanism associated with aggressive behaviour in a subset of iMBs. Promising results have been found in the telomere length distribution among the iMB molecular subgroups: SHH iMBs had a higher frequency of High (H) telomeres length (85%) than NON-SHH/NON-WNT iMBs (p=0.046), which were more frequently associated with Medium (M) telomeres length. CONCLUSIONS: ALT activation in infant MBs (10%) could be a novel target for risk-stratification and personalized therapy. It may be useful to examine ALT as a potential predictor of aggressive behaviour and as a promising novel therapeutic approach for a subset of these tumors in the diagnostic workup
HGG-09. MicroRNAs expression profile in Meningioma 1 (MN1) gene altered astroblastoma
No full textAstroblastoma is a rare glial neoplasm arising more frequently in young, predominantly female, patients and with unclear clinical behavior and outcome. The diagnostic molecular alteration is the rearrangement of meningioma 1 (MN1) gene.However, little is known about the specific mechanism of tumor development driven by such genetic change. microRNAs (miRNAs) are important gene expression regulators with strong implications in several biological processes. In this study we investigated the microRNAs’ expression and regulation in MN1 altered neoplasms. We collected a cohort of 14 formalin-fixed, paraffin-embedded (FFPE) tumor samples histologically defined classified as astroblastoma. The DNA methylation analysis showed that only 8 cases harbored the MN1 rearrangement characteristic of astroblastoma. The 8 MN1 altered tumors were analyzed for their expression pattern of miRNAs by Nanostring technology. Thirty-nine deregulated miRNAs were found in the 8 astroblastomas compared to normal brain tissue. In order to understand the underlying mechanisms of the miRNAs aberrant expression, we first investigated the methylation status of themicroRNA promoters. Thirty-two out 39 deregulated miRNA resulted epigenetically regulated. with methylation status coherent with microRNA expression in 14/32 miRNAs.. Secondly, we investigated the hypothesis of a genomic alteration as a reason for the abnormal expression of the remaining 18/32 deregulated miRNAs by analyzing the Copy Number Variation (CNV) of tumor samples. but no alteration was found on miRNAs chromosome loci. Finally, we identified validated targets of the 32 deregulated miRNAs and uncovered biological processes putatively correlated to miRNA target genes, clinically and pathologically relevant in MN1-altered astroblastomas. Our findings shed light on the biology of this rare disease with potential implications on prognostic markers and therapy
