Evolution of DNA repair defects during malignant progression of low-grade gliomas after temozolomide treatment

Abstract 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...
Source: Acta Neuropathologica - Category: Neurology Source Type: research

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Publication date: Available online 13 October 2019Source: Seminars in Cancer BiologyAuthor(s): Vikram Shaw, Suyash Srivastava, Sanjay K. SrivastavaAbstractThe recent development of high throughput compound screening has allowed drug repurposing to emerge as an effective avenue for discovering novel treatments for cancer. FDA-approved antipsychotic drugs fluspirilene, penfluridol, and pimozide are clinically used for the treatment of psychotic disorders, primarily schizophrenia. These compounds, belong to diphenylbutylpiperidine class of antipsychotic drugs, are the potent inhibitors of dopamine D2 receptor and calcium chan...
Source: Seminars in Cancer Biology - Category: Cancer & Oncology Source Type: research
This study was carried out to elucidate the antineoplastic effect of quercetin through regulating both Notch and Hh pathways, apoptosis, cell proliferation and CK2α activity.Main methodsHepatocellular carcinoma was induced in male Sprague Dawley rats by thioacetamide. Quercetin was administered in both protective and curative doses. Parameters of liver function and oxidative stress were assessed. CK2α, Notch and Hh pathways were evaluated using RT-PCR and ELISA. Apoptosis was investigated by detecting caspase-3, caspase-8 and p53. Proliferative and cell cycle markers as cyclin D1 and Ki-67 were detected immunoh...
Source: Life Sciences - Category: Biology Source Type: research
Abstract Etoposide (VP-16) is the topoisomerase 2 (Top2) inhibitor used for treating of glioma patients however at high dose with serious side effects. It induces DNA double-strand breaks (DSBs). These DNA lesions are repaired by non-homologous DNA end joining (NHEJ) mediated by DNA-dependent protein kinase (DNA-PK). One possible approach to decrease the toxicity of etoposide is to reduce the dose while maintaining the anticancer potential. It could be achieved through combined therapy with other anticancer drugs. We have assumed that this objective can be obtained by (1) a parallel topo2 α inhibition and (2...
Source: Molecular Biology Reports - Category: Molecular Biology Authors: Tags: Mol Biol Rep Source Type: research
ConclusionsIO seems to be ineffective in HmGB with somatic mut regardless the onset of diagnosis (newly/recurrent) or type of Hm phenotype. However, germline HmGB may have durable responses to IO. Further investigation is needed to determine the potential antitumor immune response in this population.Legal entity responsible for the studyThe authors.FundingThis work was supported in part by the Sheikh Khalifa Al Nahyan Ben Zayed Institute for Personalized Cancer Therapy, and the MD Anderson Cancer Center Support grant (P30 CA016672) MD Anderson Cancer Center.DisclosureAll authors have declared no conflicts of interest.
Source: Annals of Oncology - Category: Cancer & Oncology Source Type: research
Conclusions1. Glioblastoma, anaplastic glioma and neuroblastoma cell lines have a high sensitivity to Cabazitaxel in vitro. 2. Cell lines with MGMT methylation and MMR expression (A172 and LN 229) are the most sensitive. Of them, line A172 presents a p53 wild type, and therefore, a greater sensitivity to Cabazitaxel. 3. The expression of CD133 correlates inversely with the values of IC50 to Cabazitaxel, and may also be a predictor of response.Legal entity responsible for the studyUGR.FundingHas not received any funding.DisclosureAll authors have declared no conflicts of interest.
Source: Annals of Oncology - Category: Cancer & Oncology Source Type: research
ConclusionsA subgroup of recurrent MMRd HGG patients might benefit from Pem, especially those with anaplastic gliomas. There was a trend for a longer PFS and OS in PTS with aMMRd. Analyses for identifying additional molecular predictive factors is ongoing.Legal entity responsible for the studyThe authors.FundingHas not received any funding.DisclosureAll authors have declared no conflicts of interest.
Source: Annals of Oncology - Category: Cancer & Oncology Source Type: research
In conclusion, our findings promote our understanding of the roles of DNA methylation in MGMT umethylated GBMs and offer a very promising TMZ-sensitivity predictive signature for these GBMs that could be tested prospectively.
Source: Frontiers in Genetics - Category: Genetics & Stem Cells Source Type: research
In conclusion, although the CNS is not any more considered as an "immunological sanctuary" and despite some encouraging experimental and clinical results in CNS oncotherapy, the routine application of IT in case of MGs is still awaited. PMID: 31533142 [PubMed - in process]
Source: Magyar Onkologia - Category: Cancer & Oncology Authors: Tags: Magy Onkol Source Type: research
Abstract Recent advances in single-cell RNA sequencing (scRNA-seq) have endowed researchers with the ability to detect and analyze the transcriptomes of individual cancer cells. In the present study, 16,128 tumor cells from EGFR wild-type and EGFRvIII mutant cells were profiled by scRNA-seq. Analyses of scRNA-seq data from both U87MG and U87MG-EGFRvIII libraries revealed inherent heterogeneity in gene expression and biological processes. The cells stably expressing EGFRvIII showed enhanced transcriptional activities and a relatively homogeneous pattern, which manifested as less diverse distributions, gene expressi...
Source: Aging - Category: Biomedical Science Authors: Tags: Aging (Albany NY) Source Type: research
Conclusions: We identified a hyper-mutated subgroup among IDH-wt GBMs in adults < 55 years that had improved prognosis. Two cases were ultra-mutated and characterized by the presence of at least 25% giant cells, MMR mutations, and MSI. Since high TML has been associated with response to immune checkpoint inhibition in paediatric gliomas, the identification of a subtype of ultra-mutated IDH-wt GBM may have implications for immunotherapy.
Source: Cancers - Category: Cancer & Oncology Authors: Tags: Article Source Type: research
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