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Project description:Loss of function mutations in SMARCB1 are prevalent in pediatric atypical teratoid rhabdoid tumors (ATRTs) and confer an oncogenic dependency on EZH2, providing a compelling rationale for treating these genetically defined cancers via EZH2 inhibition (EZH2i). EZH2i results in tumor regression in SMARCB1-deficient tumors in preclinical studies, but the molecular mechanism has not been fully elucidated. Here we found that the sensitivity of SMARCB1-deficient tumors to EZH2i is associated with the viral mimicry response that depends on both double-stranded RNA (dsRNA) and cytoplasmic DNA sensing pathways. Unlike other epigenetic therapies targeting transcriptional repressors, viral mimicry by EZH2i in SMARCB1-deficient tumors is not triggered by crypt initiation of endogenous retroelements, but rather mediated by increased expression of genes enriched for intronic inverted-repeat Alu (IR-Alu) elements. Interestingly, we found that interferon-stimulated genes (ISGs) are highly enriched for dsRNA-forming intronic IR-Alu elements, suggesting a positive feedback loop whereby interferon response leads to dsRNA formation from intronic ISGs and activation of viral mimicry. Moreover, EZH2i in ATRT cells also enhances the expression of full-length LINE-1 elements, leading to genomic instability and cGAS/STING response in a process dependent on reverse transcriptase activity. Supporting this mechanism, co-depletion of dsRNA sensing and cytoplasmic DNA sensing completely rescues the viral mimicry response to EZH2i in SMARCB1-deficient tumors.
2024-09-05 | GSE213249 | GEO
Project description:Loss of function mutations in SMARCB1 are prevalent in pediatric atypical teratoid rhabdoid tumors (ATRTs) and confer an oncogenic dependency on EZH2, providing a compelling rationale for treating these genetically defined cancers via EZH2 inhibition (EZH2i). EZH2i results in tumor regression in SMARCB1-deficient tumors in preclinical studies, but the molecular mechanism has not been fully elucidated. Here we found that the sensitivity of SMARCB1-deficient tumors to EZH2i is associated with the viral mimicry response that depends on both double-stranded RNA (dsRNA) and cytoplasmic DNA sensing pathways. Unlike other epigenetic therapies targeting transcriptional repressors, viral mimicry by EZH2i in SMARCB1-deficient tumors is not triggered by crypt initiation of endogenous retroelements, but rather mediated by increased expression of genes enriched for intronic inverted-repeat Alu (IR-Alu) elements. Interestingly, we found that interferon-stimulated genes (ISGs) are highly enriched for dsRNA-forming intronic IR-Alu elements, suggesting a positive feedback loop whereby interferon response leads to dsRNA formation from intronic ISGs and activation of viral mimicry. Moreover, EZH2i in ATRT cells also enhances the expression of full-length LINE-1 elements, leading to genomic instability and cGAS/STING response in a process dependent on reverse transcriptase activity. Supporting this mechanism, co-depletion of dsRNA sensing and cytoplasmic DNA sensing completely rescues the viral mimicry response to EZH2i in SMARCB1-deficient tumors.
2024-09-05 | GSE213248 | GEO
Project description:Inhibiting EZH2 Targets Atypical Teratoid Rhabdoid Tumor by Triggering Viral Mimicry via Both RNA and DNA Sensing Pathways
| PRJNA880260 | ENA
Project description:Inhibiting EZH2 Targets Atypical Teratoid Rhabdoid Tumor by Triggering Viral Mimicry via Both RNA and DNA Sensing Pathways [RNA-Seq]
| PRJNA880266 | ENA
Project description:Inhibiting EZH2 Targets Atypical Teratoid Rhabdoid Tumor by Triggering Viral Mimicry via Both RNA and DNA Sensing Pathways [CUT&RUN]
| PRJNA880265 | ENA
Project description:BACKGROUND: To describe therapeutic approaches in children with atypical Teratoid Rhabdoid Tumours (ATRT) in France. METHODS: Observational study including all children less than 18 years old diagnosed with ATRT in France between 2009 and 2011. RESULTS: Forty seven children were included in this retrospective study. Six patients received no curative treatment while forty-one patients had a curative project. Median age was 1.5 years (range 0-16). The disease was disseminated in 10 patients. Surgical resection was complete in 21 cases. Chemotherapy was administered in 41 children. Twenty-six patients received upfront Vincristine-Methotrexate (5g/m2 x 3) with intra-thecal Methotrexate, which was stopped in eleven patients: in four cases the disease progressed and in seven cases the toxicities were manageable. Fifteen children received different chemotherapy courses and in four of them the diseases progressed. Eight patients underwent second-look surgery. Radiotherapy was administered in 17 patients at a median time of 19 weeks (13-44) after diagnosis. High-dose chemotherapy (HDCT) was given in 9 children and maintenance therapy in 5 children, starting at respectively 35 and 42 weeks after diagnosis. Median follow-up was 26 months (0.6-47). Median time for progression was 5 months. Two-years overall survival was 32% + /-8%. Median survival was 8 months. DISCUSSION: The survival rate of children with ATRT remains poor, the addition of VM is easily manageable but its benefit remains uncertain. The disease progressed mostly before radiotherapy. Future trials should focus on the delay of radiotherapy and the benefit of HDCT.
| S-EPMC4046281 | biostudies-literature
Project description:Atypical teratoid rhabdoid tumor (ATRT) is an aggressive pediatric brain tumor with limited therapeutic options. The hypothesis for this study was that the Wnt pathway triggered by the Wnt5B ligand plays an important role in ATRT biology. To address this hypothesis, the role of WNT5B and other Wnt pathway genes was analyzed in ATRT tissues and ATRT primary cell lines.Transcriptome-sequencing analyses were performed using nanoString platforms, immunohistochemistry, Western blotting, quantitative reverse transcriptase PCR, immunoprecipitation, short interference RNA studies, cell viability studies, and drug dose response (DDR) assays.Our transcriptome-sequencing results of Wnt pathway genes from ATRT tissues and cell lines indicated that the WNT5B gene is significantly upregulated in ATRT samples compared with nontumor brain samples. These results also indicated a differential expression of both canonical and noncanonical Wnt genes. Imunoprecipitation studies indicated that Wnt5B binds to Frizzled1 and Ryk receptors. Inhibition of WNT5B by short interference RNA decreased the expression of FRIZZLED1 and RYK. Cell viability studies a indicated significant decrease in cell viability by inhibiting Frizzled1 receptor. DDR assays showed promising results with some inhibitors.These promising therapeutic options will be studied further before starting a translational clinical trial. The success of these options will improve care for these patients.
| S-EPMC4483069 | biostudies-literature
Project description:Atypical teratoid/rhabdoid tumor (AT/RT) is a rare CNS cancer that typically occurs in children younger than 3 years of age. Histologically, AT/RTs are embryonal tumors that contain a rhabdoid component as well as areas with primitive neuroectodermal, mesenchymal, and epithelial features. Compared to other CNS tumors of childhood, AT/RTs are characterized by their rapid growth, short symptomatic prodrome, and large size upon presentation, often leading to brain compression and intracranial hypertension requiring urgent intervention. For decades, the mainstay of care has been a combination of maximal safe surgical resection followed by adjuvant chemotherapy and radiotherapy. Despite advances in each of these modalities, the relative paucity of data on these tumors, their inherently aggressive course, and a lack of molecular data have limited advances in treatment over the past 3 decades. Recent large-scale, multicenter interdisciplinary studies, however, have significantly advanced our understanding of the molecular pathogenesis of these tumors. Multiple clinical trials testing molecularly targeted therapies are underway, offering hope for patients with AT/RT and their families.
| S-EPMC6656328 | biostudies-literature
Project description:IntroductionOverexpression of the Polycomb repressive complex 2 (PRC2) subunit Enhancer of Zeste 2 (EZH2) occurs in several malignancies, including prostate cancer, breast cancer, medulloblastoma, and glioblastoma multiforme. Recent evidence suggests that EZH2 may also have a role in rhabdoid tumors. Atypical teratoid/rhabdoid tumor (ATRT) is a rare, high-grade embryonal brain tumor that occurs most commonly in young children and carries a very poor prognosis. ATRTs are characterized by absence of the chromatin remodeling protein SMARCB1. Given the role of EZH2 in regulating epigenetic changes, we investigated the role of EZH2 in ATRT.MethodsMicroarray analysis was used to evaluate expression of EZH2 in ATRT tumor samples. We used shRNA and a chemical inhibitor of EZH2 to examine the impact of EZH2 inhibition on cell growth, proliferation, and tumor cell self-renewal.ResultsHere, we show that targeted disruption of EZH2 by RNAi or pharmacologic inhibition strongly impairs ATRT cell growth, suppresses tumor cell self-renewal, induces apoptosis, and potently sensitizes these cells to radiation. Using functional analysis of transcription factor activity, we found the cyclin D1-E2F axis to be repressed after EZH2 depletion in ATRT cells.ConclusionsOur observations provide evidence that EZH2 disruption alters cell cycle progression and may be an important new therapeutic target, particularly in combination with radiation, in ATRT.
| S-EPMC3548579 | biostudies-literature
Project description:Atypical teratoid/rhabdoid tumors (AT/RTs) are lethal central nervous system tumors, which are primarily diagnosed in infants. Current treatments for AT/RTs include surgery, radiotherapy, and chemotherapy; these treatments have poor prognoses and challenging side effects. The pivotal genetic event in AT/RT pathogenesis comprises the inactivation of SMARCB1 or SMARCA4. Recent epigenetic studies have demonstrated mutual and subtype-specific epigenetic derangements that drive tumorigenesis; the exploitation of these potential targets might improve the dismal treatment outcomes of AT/RTs. This review aims to summarize the literature concerning targeted molecular therapies for pediatric AT/RTs.
| S-EPMC9218972 | biostudies-literature