Snf5F/Fp53L/LGFAP-Cre tumors and human AT/RT show similar gene expression signatures
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ABSTRACT: Human medulloblastoma (MB) can be segregated into four major categories based on gene expression patterns: Hedgehog (HH) subtype, Wnt subtype, Group 3, and Group 4. However, they all exhibit strikingly different gene expression profiles from Atypical Teratoid/Rhabdoid Tumor (AT/RT). We re-analyzed published gene expression microarray dataset of pediatric brain tumors to identify a gene expression profile that clearly distinguished human AT/RT from human MB. We used this profile, choosing only genes that have clear murine orthologs, to compare tumors from Snf5F/Fp53L/LGFAP-Cre mice (in C57Bl/6 strain background) with MB from Ptc1+/- mice (in mixed C57Bl/6 and 129Sv strain background). Snf5F/Fp53L/LGFAP-Cre tumors are clearly very different from mouse MB and the markers that distinguish human AT/RT from human MB also distinguish the mouse tumors.
Project description:Pediatric embryonal brain tumor (PEBT), which includes medulloblastoma (MB), primitive neuroectodermal tumor (PNET) and atypical teratoid/rhabdoid tumor (AT/RT), is the second most prevalent pediatric tumor type among brain tumors of childhood. AT/RT is highly malignant and is often misdiagnosed as MB and PNET. Distinguishing AT/RT from PNET/MB is of clinical significance since the survival rate of AT/RT patients is much lower. The diagnosis of AT/RT relies primarily on the morphologic assessment and immunohistochemistry (IHC) staining on a few known markers such as the lack of INI1 protein expression. However, in our clinical practice we observed several AT/RT-like tumors, which fulfilled histopathologic and all other biomarker criteria for AT/RT diagnosis, still showed retained INI1 immunoreactivity. Recent studies also reported retained INI1 immunoreactivity among certain diagnosed AT/RTs. It is therefore necessary to re-evaluate INI1(+), AT/RT-like cases. Sanger sequencing, array CGH and mRNA microarray analyses were performed on PEBT samples for studying their genomics landscapes. AT/RT and INI(+) AT/RT-like patients had similar survival rate, and global array CGH analysis and INI1 gene sequencing showed there is no differential chromosomal aberration marker between INI1(-) AT/RT and INI(+) AT/RT-like cases. We did not misdiagnose MB or PNET as AT/RT-like cases since transcriptome profiling revealed that not only AT/RT and INI(+) AT/RT-like cases expressed distinct mRNA and microRNA profiles, and their gene expression patterns were different from those of MBs and PNETs. AT/RTs shared the closest transcriptome profile to embryonic stem cells, INI1(+) AT/RT-like tumors were more similar to somatic neural stem cell, while MBs were closer to fetal brain. Novel biomarkers were identified to distinguish INI1(-) AT/RTs, INI1(+) AT/RT-like cases and MBs. Our studies disclosed a novel INI1(+) ATRT-like subtype among Taiwanese pediatric cases. New diagnostic biomarkers, as well as new therapeutic tactics, can be developed according to the transcriptome information unveiled in this work.
Project description:Pediatric embryonal brain tumor (PEBT), which includes medulloblastoma (MB), primitive neuroectodermal tumor (PNET) and atypical teratoid/rhabdoid tumor (AT/RT), is the second most prevalent pediatric tumor type among brain tumors of childhood. AT/RT is highly malignant and is often misdiagnosed as MB and PNET. Distinguishing AT/RT from PNET/MB is of clinical significance since the survival rate of AT/RT patients is much lower. The diagnosis of AT/RT relies primarily on the morphologic assessment and immunohistochemistry (IHC) staining on a few known markers such as the lack of INI1 protein expression. However, in our clinical practice we observed several AT/RT-like tumors, which fulfilled histopathologic and all other biomarker criteria for AT/RT diagnosis, still showed retained INI1 immunoreactivity. Recent studies also reported retained INI1 immunoreactivity among certain diagnosed AT/RTs. It is therefore necessary to re-evaluate INI1(+), AT/RT-like cases. Sanger sequencing, array CGH and mRNA microarray analyses were performed on PEBT samples for studying their genomics landscapes. AT/RT and INI(+) AT/RT-like patients had similar survival rate, and global array CGH analysis and INI1 gene sequencing showed there is no differential chromosomal aberration marker between INI1(-) AT/RT and INI(+) AT/RT-like cases. We did not misdiagnose MB or PNET as AT/RT-like cases since transcriptome profiling revealed that not only AT/RT and INI(+) AT/RT-like cases expressed distinct mRNA and microRNA profiles, and their gene expression patterns were different from those of MBs and PNETs. AT/RTs shared the closest transcriptome profile to embryonic stem cells, INI1(+) AT/RT-like tumors were more similar to somatic neural stem cell, while MBs were closer to fetal brain. Novel biomarkers were identified to distinguish INI1(-) AT/RTs, INI1(+) AT/RT-like cases and MBs. Our studies disclosed a novel INI1(+) ATRT-like subtype among Taiwanese pediatric cases. New diagnostic biomarkers, as well as new therapeutic tactics, can be developed according to the transcriptome information unveiled in this work. 2 AT/RT-like cases and 7 AT/RT cases are subjected to transcriptome analysis.
Project description:Four main medulloblastoma (MB) molecular subtypes have been identified based on transcriptional, DNA methylation and genetic profiles. However, it is currently not known whether MB subtypes have their own specific 3D genome architecture. Hi-C maps were globally stable across MB subtypes. However, among the 3D genome features we tested, boundary strengths of topologically associating domains (TADs) were the best at classifying MB samples – including Group 3 and Group 4 specimens - according to their known molecular subtypes. Although boundary strength was not generally associated with differential gene expression between subtypes, we found that Group 3 and Group 4 specimens had differential TAD boundary strengths near genes that are uniquely expressed in their respective lineages of origin. Accordingly, we provide examples of TAD boundary reorganization that clearly distinguish Group 3 and 4 samples at these developmentally important genomic sites. TAD boundary strength allows classification of MB molecular subtypes, indicating that the shape of the 3D genome is unique to each molecular subtype. Genome topologies of Group 3 and 4 tumors are shaped differently at key lineage genes, but these differences are not strongly predictive of changes in gene expression. 3D genome architecture might be a fossil of the lineages of origin of MB subtypes.
Project description:Medulloblastoma (MB) is an embryonal tumor of the cerebellum and a highly malignant childhood brain tumor. Cell-free circulating tumor DNA (ctDNA) from the cerebrospinal fluid (CSF) of patients with brain tumors faithfully represent genomic alterations of brain tumors. Distinct epigenetic signatures among subgroups of MB allow us to detect epigenetic alterations in CSF to aid classify and guide therapy of MB tumors. Here, we evaluate DNA methylation and hydroxymethylation of ctDNA derived from small amount of CSF (200 µL) and matched tumor DNA from 3 MB patients. We find highly concordance of DNA methylation and hydroxymethylation between CSF ctDNA and tumor DNA, especially in CpG islands. Importantly, CSF ctDNA can mostly recapitulate the dynamic changes of DNA methylation and hydroxymehtylation in tumor species compared to healthy cerebellums. Those MB tumor signature CpGs’ DNA methylation status are recovered in CSF ctDNA can clearly distinguish MB subgroups by utilizing public large cohort data. We further identified potential diagnostic and prognostic DNA methylation markers in CSF ctDNA. Our results show that CSF ctNDA methylation and hydroxymethylation can be a minimal invasive method to assess epigenetic alterations of MB, which is complementary to current diagnoses of MB tumors.
Project description:Embryonal tumors of the central nervous system (CNS) represent a highly malignant tumor group of medulloblastoma (MB), atypical teratoid/rhabdoid tumor (AT/RT), and primitive neuroectodermal tumor (PNET) that frequently afflict children. In this study, we report transcriptome traits in MB by using gene expression microarray analyses. We also compare MB dataset with AT/RT cases and AT/RT-like cases.
Project description:Medulloblastoma (MB) is an embryonal tumor of the cerebellum and a highly malignant childhood brain tumor. Cell-free circulating tumor DNA (ctDNA) from the cerebrospinal fluid (CSF) of patients with brain tumors faithfully represent genomic alterations of brain tumors. Distinct epigenetic signatures among subgroups of MB allow us to detect epigenetic alterations in CSF to aid classify and guide therapy of MB tumors. Here, we evaluate DNA methylation of ctDNA derived from small amount of CSF (200 µL) and matched tumor DNA from four subtypes of MB patients. We find highly concordance of DNA methylation between CSF ctDNA and tumor DNA in a subtype manner. Our results show that CSF ctNDA methylation can be a minimal invasive precisely method to assess epigenetic alterations of MB in a subtype manner, which is complementary to current diagnoses of MB tumors.
Project description:Medulloblastoma (MB) is an embryonal tumor of the cerebellum and a highly malignant childhood brain tumor. Cell-free circulating tumor DNA (ctDNA) from the cerebrospinal fluid (CSF) of patients with brain tumors faithfully represent genomic alterations of brain tumors. Distinct epigenetic signatures among subgroups of MB allow us to detect epigenetic alterations in CSF to aid classify and guide therapy of MB tumors. Here, we evaluate DNA methylation of ctDNA derived from small amount of CSF (200 µL) and matched tumor DNA from four subtypes of MB patients. We find highly concordance of DNA methylation between CSF ctDNA and tumor DNA in a subtype manner. Our results show that CSF ctNDA methylation can be a minimal invasive precisely method to assess epigenetic alterations of MB in a subtype manner, which is complementary to current diagnoses of MB tumors.
Project description:Genomic rearrangements leading to intragenic gene fusion are mainly found in some types of haematopoietic malignancies and sarcomas. Recently they have been described also in carcinomas such as the papillary thyroid histotype (60%-70%) and the Hürthle thyroid tumours (58%). The presence of junction oncogene constitutes an area of exciting research for emerging therapy as targeting the RET-PTC1 fusion oncogene by using small interfering RNA (siRNA) strategies since it is present only in the tumour cells and not in the surrounding normal cells. Therefore, we developed a siRNA against RET-PTC1 junction and assess its efficiency on the human papillary thyroid carcinoma cell line TPC-1 which spontaneously harbours the RET-PTC1 oncogene. The targeted genes are assessed by microarray analysis by comparing the regulated genes by the siRNA_RET-PTC1 vs a siRNA_RET developed on the RET part of the mRNA minus the siRNA_control that contain four mutation within the RET-PTC1 sequence. To test the targeted genes in the TPC-1 cell line that spontaneously harbours RET-PTC1 junction of two siRNAs developed: Within the RET-PTC1 junction, and in the mRNA RET part. A non-specific siRNA harbouring 4 mutations within the RET-PTC1 sequence was used as negative control (siRNA_control). By real-time PCR (Q-RT-PCR) we demonstrated that both siRNAs (siRNA_RET-PTC1 and siRNA_RET) significantly reduce RET mRNA levels of about 85 % in TPC-1 cells. The negative control did not show an effect of RET mRNA levels. Three independent transfections were performed on TPC-1 cells using 5 µl of Lipofectamine 2000 transfection reagent (Invitrogen, Cergy-Pontoise, France) and 50nM of i) siRNA_RET-PTC1 or ii) siRNA_RET or iii) siRNA_control that harbour 4 mutations within its sequence. Total RNAs of untreated cells and transfected cells were purified using the RNA cleanup and concentration kit (QIAGEN, Hilden, Germany) and gathered in 4 pools : 1) TPC-1 harbouring RET-PTC1 ; 2) TPC-1 silenced for RET-PTC1 with siRNA RET-PTC1 ; 3) TPC-1 silenced for siRNA RET ; 4) TPC-1 treated with the siRNA control.
Project description:Expression analysis from two genetically engineered mouse models of osteosarcoma determine the expression profile of mouse osteosarcoma Human osteosarcoma (OS) is comprised of three different subtypes: fibroblastic, chondroblastic and osteoblastic. We previously generated a mouse model of fibroblastic OS by conditional deletion of p53 and Rb in osteoblasts. Here we report an accurate mouse model of the osteoblastic subtype using shRNA-based suppression of p53. Like human OS, tumors frequently present in the long bones and preferentially disseminate to the lungs; features less consistently modeled using Cre:lox approaches. Our approach allowed direct comparison of the in vivo consequences of targeting the same genetic drivers using different technology. This demonstrated that the effects of Cre:lox and shRNA mediated knock-down are qualitatively different, at least in the context of osteosarcoma. Through the use of complementary genetic modification strategies we have established a model of a distinct clinical subtype of OS that was not previously represented and more fully recapitulated the clinical spectrum of this human tumor. 4 primary tumors from Cre:lox OS model; 4 primary tumors from shRNA OS model.