Ontology highlight
ABSTRACT:
PROVIDER: PRJNA956444 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR24298940_1.fastq.gz | Fastqsanger.gz | |||
| SRR24298940_2.fastq.gz | Fastqsanger.gz | |||
| SRR24298941_1.fastq.gz | Fastqsanger.gz | |||
| SRR24298941_2.fastq.gz | Fastqsanger.gz | |||
| SRR24298942_1.fastq.gz | Fastqsanger.gz |
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Project description:This is a Phase II, non-randomized, open-label study to evaluate temozolomide in combination with olaparib in patients with MGMT promoter hypermethylated advanced colorectal cancer.
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Project description:Temozolomide (TMZ) is an important first-line treatment for glioblastoma (GBM), but there are limitations to TMZ response in terms of durability and dependence on the promoter methylation status of the DNA repair gene O6-methylguanine DNA methyltransferase (MGMT). MGMT-promoter-hypermethylated (MGMT-M) GBMs are more sensitive to TMZ than MGMT-promoter-hypomethylated (MGMT-UM) GBMs. Moreover, TMZ resistance is inevitable even in TMZ-sensitive MGMT-M GBMs. Hence, epigenetic reprogramming strategies are desperately needed in order to enhance TMZ response in both MGMT-M and MGMT-UM GBMs. In this study, we present novel evidence that the epigenetic reactivation of Tumor Suppressor Candidate 3 (TUSC3) can reprogram sensitivity of GBM stem cells (GSCs) to TMZ irrespective of MGMT promoter methylation status. Interrogation of TCGA patient GBM datasets confirmed TUSC3 promoter regulation of TUSC3 expression and also revealed a strong positive correlation between TUSC3 expression and GBM patient survival. Using a combination of loss-of-function, gain-of-function and rescue studies, we demonstrate that TUSC3 reactivation is associated with enhanced TMZ response in both MGMT-M and MGMT-UM GSCs. Further, we provide novel evidence that the demethylating agent 5-Azacitidine (5-Aza) reactivates TUSC3 expression in MGMT-M GSCs, whereas the combination of 5-Aza and MGMT inhibitor Lomeguatrib is necessary for TUSC3 reactivation in MGMT-UM GSCs. Lastly, we propose a pharmacological epigenetic reactivation strategy involving TUSC3 that leads to significantly prolonged survival in MGMT-M and MGMT-UM orthotopic GSCs models. Collectively, our findings provide a framework and rationale to further explore TUSC3-mediated epigenetic reprogramming strategies that could enhance TMZ sensitivity and outcomes in GBM. Mechanistic and translational evidence gained from such studies could contribute towards optimal design of impactful trials for MGMT-UM GBMs that currently do not have good treatment options.
2024-11-26 | GSE282886 | GEO
Project description:Temozolomide (TMZ) has been used for the treatment of glioblastoma (GBM) since last decade, but its treatment benefits are limited by acquired resistance, a process that remains incompletely understood. Here we report that a novel enhancer, located between the promoters of Ki67 and O6-methylguanine-DNA-methyltransferase (MGMT) genes, is activated in TMZ-resistant patient-derived xenograft (PDX) lines as well as in recurrent tumor samples. Activation of the enhancer correlates with increased MGMT expression, a major known mechanism for TMZ resistance. We show that forced activation of the enhancer in cell lines with low MGMT expression results in elevated MGMT expression. Deletion of this enhancer in cell lines with high MGMT expression leads to reduced levels of MGMT and Ki67, increased TMZ sensitivity and impaired proliferation. Together, these studies uncover a novel mechanism that regulates MGMT expression, confers TMZ resistance and potentially regulates tumor proliferation.
2018-07-13 | GSE113816 | GEO
Project description:Acquired resistance of temozolomide (TMZ) is one of the major obstacle of glioblastoma clinical treatment and the mechanism of TMZ resistance is still not very clear. In the presented research we show that deletion of rs16906252-associated MGMT enhancer in MGMT negative glioma cells induced increase sensitivity to temozolomide and combination of RNA-seq and Capture HiC identified several long-range target genes of rs16906252-associated MGMT enhancer. In addition, HiC data shows alterations of chromatin structures in glioma cells survived from high-dosage TMZ treatment and changes of TADs influence rs16906252-associated MGMT enhancer’s long-range regulations of target genes. Our study suggests rs16906252-associated MGMT enhancer regulates glioma cells’ TMZ sensitivity by long-range regulations of several target genes, which is a novel mechanism of regulation of TMZ sensitivity in glioma cells.
2020-04-02 | GSE129476 | GEO
Project description:Patients diagnosed with glioblastoma (GBM) with sustained synthesis of the DNA repair enzyme, O6-methyl guanine DNA methytransferase (MGMT), are rendered resistant to Temozolomide (TMZ) chemotherapy. Here, we hypothesized that pretreatment with the proteasome inhibitor Bortezomib (BTZ, Velcade) might sensitize these GBM to TMZ by depleting MGMT.
2019-08-20 | PXD007193 | Pride
Project description:Temozolomide (TMZ) increases the overall survival of patients with glioblastoma (GBM), but its role in the clinical management of diffuse low-grade gliomas (LGG) is still being defined. DNA hypermethylation of the O 6 -methylguanine-DNA methyltransferase (MGMT) promoter is associated with an improved response to TMZ treatment, while inactivation of the DNA mismatch repair (MMR) pathway is associated with therapeutic resistance and TMZ-induced mutagenesis. We previously demonstrated that TMZ treatment of LGG induces driver mutations in the RB and AKT-mTOR pathways, which may drive malignant progression to secondary GBM. To better understand the mechanisms underlying TMZ-induced mutagenesis and malignant progression, we explored the evolution of MGMT methylation and genetic alterations affecting MMR genes in a cohort of 34 treatment-naïve LGGs and their recurrences. Recurrences with TMZ-associated hypermutation had increased MGMT methylation compared to their untreated initial tumors and higher overall MGMT methylation compared to TMZ-treated non-hypermutated recurrences. A TMZ-associated mutation in one or more MMR genes was observed in five out of six TMZ-treated hypermutated recurrences. In two cases, pre-existing heterozygous deletions encompassing MGMT, or an MMR gene, were followed by TMZ-associated mutations in one of the genes of interest. These results suggest that tumor cells with methylated MGMT may undergo positive selection during TMZ treatment in the context of MMR deficiency.
| EGAS00001001179 | EGA
Project description:Glioblastoma (GBM) is the most aggressive and lethal CNS tumor with only 14 months median overall survival after diagnosis and ∼5% 5-years survival rate. The treatment strategy is mainly surgery and/or radiation therapy, both combined with adjuvant temozolomide (TMZ) chemotherapy. TMZ treatment results in methylation of DNA purine bases, where the primary cytotoxic lesion is O6-methylguanine that can be removed by DNA repair enzyme methylguanine methyltransferase (MGMT) when tumors express this protein. Historically, methylation of MGMT gene promoter is used as the major biomarker predicting individual tumor response to TMZ, but there are also additional biomarkers. However, most of them were developed using TCGA project collection of molecular profiles which were unproperly diagnosed as GBM and now need to be reclassified according to the most recent WHO CNS5 tumor classification. Here we for the first time compared biomarker potentials of MGMT methylation, expression levels of 361 DNA repair genes, and activation levels of 38 DNA repair pathways on updated TCGA and other samplings and validated the results on our experimental multicenter GBM patient cohort (n=50). We found that expression/activation levels of 7 and 6 emerging gene/pathway biomarkers served as high-quality positive (HR<0.61) and negative (HR>1.63), respectively, patient survival biomarkers, all performed significantly better than MGMT methylation. Positive survival biomarkers were enriched in the processes of ATM-dependent checkpoint activation and cell cycle arrest whereas negative – in excision DNA repair. We also built and characterized gene signature which was informative for GBM patient survival following TMZ administration (HR 0.27-0.44, p<0,0004; AUC 0.69-0.9).
2024-04-17 | GSE263890 | GEO
Project description:LncRNAs interact with other cellular molecules, such as DNA, RNA and proteins, to regulate various biological processes. In our study, we demonstrated that LINC01956 promoted MGMT mRNA nuclear export and led to TMZ resistance. In order to elucidate the potential molecular mechanism of LINC01956 promoting MGMT mRNA nuclear export, RNA pulldown experiments and quantitative proteomics mass-spectrometry (MS) analysis were performed.
2024-10-28 | PXD055168 | Pride
Project description:Overexpression of histone deacetylases (HDACs) in cancer commonly causes resistance to genotoxic based therapies. Here we report on the novel mechanism whereby overexpressed class I HDACs increase the resistance of glioblastoma cells to the SN1 methylating agent temozolomide (TMZ). The chemotherapeutic TMZ triggers the activation of the DNA damage response (DDR) in resistant glioma cells, leading to DNA lesion bypass and cellular survival. Mass spectrometry analysis revealed that the catalytic activity of class I HDACs stimulates the expression of the E3 ubiquitin ligase RAD18. Furthermore, the data show that RAD18 is part of the O6-methylguanine-induced DDR as TMZ induces the formation of RAD18 foci at sites of DNA damage. Downregulation of RAD18 by HDAC inhibition prevents glioma cells from activating the DDR upon TMZ exposure. Lastly, RAD18 or O6-methylguanine-DNA methyltransferase (MGMT) overexpression abolishes the sensitization effect of HDAC inhibition on TMZ-exposed glioma cells. Our study describes the mechanism whereby class I HDAC overexpression in glioma cells causes resistance to TMZ treatment. HDACs accomplish this by promoting the bypass of O6-methylguanine DNA lesions via enhancing RAD18 expression. It also provides a treatment option with HDAC inhibition to undermine this mechanism.
2022-04-01 | PXD028683 | Pride