TMZ + Olaparib for MGMT Hypermethylated Colorectal Cancer
Ontology highlight
ABSTRACT:
DISEASE(S): Colorectal Cancer,Colorectal Neoplasms
PROVIDER: 2322183 | ecrin-mdr-crc |
REPOSITORIES: ECRIN MDR
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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: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:Angiogenesis inhibitors, such as sunitinib, represent a promising strategy to improve glioblastoma (GBM) tumor response. In this study, we used the O6-methylguanine methyltransferase (MGMT)-negative GBM cell line U87MG stably transfected with MGMT (U87/MGMT) to assess whether MGMT expression affects the response to sunitinib. We showed that the addition of sunitinib to standard therapy (temozolomide [TMZ] and radiation therapy [RT]) significantly improved the response of MGMT positive but not of MGMT-negative cells. Gene expression profiling revealed alterations in the angiogenic profile, as well as differential expression of several receptor tyrosine kinases targeted by sunitinib. MGMT-positive cells displayed higher levels of vascular endothelial growth factor receptor 1 (VEGFR-1) compared with U87/EV cells, whereas they displayed decreased levels of VEGFR-2. Depleting MGMT using O6-benzylguanine suggested that the expression of these receptors was directly related to the MGMT status. Also, we showed that MGMT expression was associated with a dramatic increase in the soluble VEGFR-1/VEGFA ratio, thereby suggesting a decrease in bioactive VEGFA and a shift towards an antiangiogenic profile. The reduced angiogenic potential of MGMT-positive cells is supported by: (i) the decreased ability of their secreted factors to induce endothelial tube formation in vitro and (ii) their low tumorigenicity in vivo compared with the MGMT-negative cells. Our study is the first to show a direct link between MGMT expression and decreased angiogenicity and tumorigenicity of GBM cells and suggests the combination of sunitinib and standard therapy as an alternative strategy for GBM patients with MGMT-positive tumors. RNA was isolated from parental U87 (U87_EV) and MGMT-transfected U87 (U87_MGMT) triplicate. Pairwise gene expression differences were compared between the two cell lines. Features selected had more than 2-fold up-or down-regulated (P values of >05, unpaired Studentâs t-test with Bonferroni multiple testing correction) were identified. Database for annotation, visualization, and integrated discovery23 was used to identify enriched gene ontology (GO) biological themes.24 The GO data mining was conducted at a term specificity level 3.25 The EASE score was set at 0.05 and the minimum number of genes in a category was 5.
2012-09-11 | E-GEOD-40776 | biostudies-arrayexpress
Project description:Two cell lines were used for methylation profiling to investigate how BET protein inhibition sensitizes glioblastoma cells to temozolomide treatment by attenuating MGMT expression
2022-12-21 | GSE217515 | GEO
Project description:Angiogenesis inhibitors, such as sunitinib, represent a promising strategy to improve glioblastoma (GBM) tumor response. In this study, we used the O6-methylguanine methyltransferase (MGMT)-negative GBM cell line U87MG stably transfected with MGMT (U87/MGMT) to assess whether MGMT expression affects the response to sunitinib. We showed that the addition of sunitinib to standard therapy (temozolomide [TMZ] and radiation therapy [RT]) significantly improved the response of MGMT positive but not of MGMT-negative cells. Gene expression profiling revealed alterations in the angiogenic profile, as well as differential expression of several receptor tyrosine kinases targeted by sunitinib. MGMT-positive cells displayed higher levels of vascular endothelial growth factor receptor 1 (VEGFR-1) compared with U87/EV cells, whereas they displayed decreased levels of VEGFR-2. Depleting MGMT using O6-benzylguanine suggested that the expression of these receptors was directly related to the MGMT status. Also, we showed that MGMT expression was associated with a dramatic increase in the soluble VEGFR-1/VEGFA ratio, thereby suggesting a decrease in bioactive VEGFA and a shift towards an antiangiogenic profile. The reduced angiogenic potential of MGMT-positive cells is supported by: (i) the decreased ability of their secreted factors to induce endothelial tube formation in vitro and (ii) their low tumorigenicity in vivo compared with the MGMT-negative cells. Our study is the first to show a direct link between MGMT expression and decreased angiogenicity and tumorigenicity of GBM cells and suggests the combination of sunitinib and standard therapy as an alternative strategy for GBM patients with MGMT-positive tumors.
2012-09-11 | GSE40776 | GEO
Project description:Acquisition of resistance to the PARP inhibitor, Olaparib, constitutes a major challenge for the treatment of advanced prostate cancer. The purpose of this study was to identify molecular targets responsible for the development of acquired Olaparib resistance in advanced prostate cancer. Towards this goal, next-generation sequencing (NGS)-based gene expression profiling (RNA-Sequencing; RNA-Seq) was performed on castration-sensitive prostate cancer (CSPC)/Olaparib-sensitive LNCaP cells, castration-sensitive prostate cancer (CSPC)/Olaparib-resistant LN-OlapR cells, castration-resistant prostate cancer (CSPC)/Olaparib-sensitive C4-2B cells, and castration-resistant prostate cancer (CSPC)/Olaparib-resistant 2B-OlapR cells.
2023-12-06 | GSE249514 | 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:An upfront-intensified treatment combining all the three active cytotoxic agents in metastatic colorectal cancer (mCRC) including fluoropyrimidines, oxaliplatin, irinotecan (FOLFOXIRI) plus antiangiogenic blockade with bevacizumab significantly improved survival. No biomarkers are available for predicting sensitivity/resistance to single chemotherapeutic drugs, the simultaneous delivery of all active chemotherapeutic agents might overcome resistance to single drugs.
Temozolomide has modest but non-negligible activity (about 10%) in chemo-refractory patients with MGMT methylated mCRC. The response rate to temozolomide-based therapy in pretreated patients is increased to up to 20% when restricting the focus on those with MGMT IHC-negative/MGMT methylated and MSS cancers. Clinical and preclinical synergy has been reported for combination of temozolomide with irinotecan and fluoropyrimidines. Temozolomide could be regarded as a "targeted" chemotherapy for patients with MSS and MGMT silenced tumors. In this subgroup of patients, an intensified triplet upfront regimen including temozolomide, fluoropyrimidines, irinotecan, associated with bevacizumab, could be a novel combination in molecularly super-selected mCRC patients.
Moving from this, the investigators designed this open-label, monocentric, phase 1b study evaluating the safety of the combination regimen 5-fluorouracil, leucovorin, irinotecan, temozolomide and bevacizumab in patients with MGMT silenced and MSS mCRC.
The study will consist in a dose-escalation assessment of the safety of the treatment in subjects with previously untreated MGMT silenced, MSS mCRC. A 3 + 3 design will be used to assess the maximum tolerated dose (MTD) or maximum tested dose of the combination FLIRT-bevacizumab.
| 2362355 | ecrin-mdr-crc
Project description:Quantitative methylation-specific tests suggest that not all cells in a glioblastoma with detectable promoter methylation of the O6-methylguanine DNA methyltransferase (MGMT) gene carry a methylated MGMT allele. This observation may indicate cell subpopulations with distinct MGMT status, raising the question of the clinically relevant cutoff of MGMT methylation therapy. Epigenetic silencing of the MGMT gene by promoter methylation blunts repair of O6-methyl guanine and has been shown to be a predictive factor for benefit from alkylating agent therapy in glioblastoma. Samples of glioblastoma and respective glioblastoma-derived spheres (GS), cultured under stem cell conditions, were analyzed for the degree and pattern of MGMT promoter methylation by methylation-specific clone sequencing, MGMT gene dosage, chromatin status, and respective effects on MGMT expression and MGMT activity.
2017-12-15 | GSE108098 | GEO