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Theranostics 2020: Glioma is the most common primary malignant brain tumor in adults. Chemoresistance of temozolomide (TMZ), the first-line chemotherapeutic agent, is a major issue in...
: Glioma is the most common primary malignant brain tumor in adults. Chemoresistance of temozolomide (TMZ), the first-line chemotherapeutic agent, is a major issue in the management of patients with glioma. Alterations of alpha thalassemia/mental retardation syndrome X-linked (ATRX) gene constitute one of the most prevalent genetic abnormalities in gliomas. Therefore, elucidation of the role of ATRX contributing to TMZ resistance in glioma is urgently needed. : We performed the bioinformatics analysis of gene expression, and DNA methylation profiling, as well as RNA and ChIP-seq data sets. CRISPR-Cas9 gene editing system was used to achieve the ATRX knockout in TMZ resistant cells. In vitro and in vivo experiments were carried out to investigate the role of ATRX contributing to TMZ resistance in glioma. : We found that ATRX expression was upregulated via DNA demethylation mediated by STAT5b/TET2 complex and strengthened DNA damage repair by stabilizing PARP1 protein in TMZ resistant cells. ATRX elicited PARP1 stabilization by the down-regulating of FADD expression via the H3K27me3 enrichment, which was dependent on ATRX/EZH2 complex in TMZ resistant cells. Magnetic resonance imaging (MRI) revealed that the PARP inhibitor together with TMZ inhibited glioma growth in ATRX wild type TMZ resistant intracranial xenograft models. : The present study further illustrated the novel mechanism of the ATRX/PARP1 axis contributing to TMZ resistance. Our results provided substantial new evidence that PARP inhibitor might be a potential adjuvant agent in overcoming ATRX mediated TMZ resistance in glioma.
Topics: Animals; Antineoplastic Agents, Alkylating; Brain Neoplasms; CRISPR-Cas Systems; DNA Damage; DNA Methylation; DNA Repair; DNA, Neoplasm; DNA-Binding Proteins; Dioxygenases; Drug Resistance, Neoplasm; Enhancer of Zeste Homolog 2 Protein; Fas-Associated Death Domain Protein; Gene Editing; Gene Expression Regulation, Neoplastic; Gene Knockout Techniques; Glioma; Histone Code; Humans; Mice; Mice, Inbred BALB C; Mice, Nude; Neoplasm Proteins; Poly (ADP-Ribose) Polymerase-1; Promoter Regions, Genetic; Proto-Oncogene Proteins; STAT5 Transcription Factor; Temozolomide; Tumor Stem Cell Assay; Up-Regulation; X-linked Nuclear Protein; Xenograft Model Antitumor Assays
PubMed: 32194873
DOI: 10.7150/thno.41219 -
Neuro-oncology Jun 2021Temozolomide (TMZ) resistance in glioblastoma multiforme (GBM) is mediated by the DNA repair protein O6-methylguanine DNA methyltransferase (MGMT). MGMT promoter...
BACKGROUND
Temozolomide (TMZ) resistance in glioblastoma multiforme (GBM) is mediated by the DNA repair protein O6-methylguanine DNA methyltransferase (MGMT). MGMT promoter methylation (occurs in about 40% of patients) is associated with loss of MGMT expression (MGMT-) that compromises DNA repair, leading to a favorable response to TMZ therapy. The 60% of patients with unmethylated MGMT (MGMT+) GBM experience resistance to TMZ; in these patients, understanding the mechanism of MGMT-mediated repair and modulating MGMT activity may lead to enhanced TMZ activity. Here, we report a novel mode of regulation of MGMT protein activity by poly(ADP-ribose) polymerase (PARP).
METHODS
MGMT-PARP interaction was detected by co-immunoprecipitation. PARylation of MGMT and PARP was detected by co-immunoprecipitation with anti-PAR antibody. O6-methylguanine (O6-MetG) adducts were quantified by immunofluorescence assay. In vivo studies were conducted in mice to determine the effectiveness of PARP inhibition in sensitizing GBM to TMZ.
RESULTS
We demonstrated that PARP physically binds with MGMT and PARylates MGMT in response to TMZ treatment. In addition, PARylation of MGMT by PARP is required for MGMT binding to chromatin to enhance the removal of O6-MetG adducts from DNA after TMZ treatment. PARP inhibitors reduced PARP-MGMT binding and MGMT PARylation, silencing MGMT activity to repair O6-MetG. PARP inhibition restored TMZ sensitivity in vivo in MGMT-expressing GBM.
CONCLUSION
This study demonstrated that PARylation of MGMT by PARP is critical for repairing TMZ-induced O6-MetG, and inhibition of PARylation by PARP inhibitor reduces MGMT function rendering sensitization to TMZ, providing a rationale for combining PARP inhibitors to sensitize TMZ in MGMT-unmethylated GBM.
Topics: Animals; Antineoplastic Agents, Alkylating; Cell Line, Tumor; DNA Damage; DNA Modification Methylases; DNA Repair Enzymes; Dacarbazine; Glioblastoma; Guanine; Humans; Mice; Poly ADP Ribosylation; Poly(ADP-ribose) Polymerase Inhibitors; Temozolomide; Tumor Suppressor Proteins
PubMed: 33433610
DOI: 10.1093/neuonc/noab003 -
Neuro-oncology Jul 2023Efficient DNA repair in response to standard chemo and radiation therapies often contributes to glioblastoma (GBM) therapy resistance. Understanding the mechanisms of...
BACKGROUND
Efficient DNA repair in response to standard chemo and radiation therapies often contributes to glioblastoma (GBM) therapy resistance. Understanding the mechanisms of therapy resistance and identifying the drugs that enhance the therapeutic efficacy of standard therapies may extend the survival of GBM patients. In this study, we investigated the role of KDM1A/LSD1 in DNA double-strand break (DSB) repair and a combination of KDM1A inhibitor and temozolomide (TMZ) in vitro and in vivo using patient-derived glioma stem cells (GSCs).
METHODS
Brain bioavailability of the KDM1A inhibitor (NCD38) was established using LS-MS/MS. The effect of a combination of KDM1A knockdown or inhibition with TMZ was studied using cell viability and self-renewal assays. Mechanistic studies were conducted using CUT&Tag-seq, RNA-seq, RT-qPCR, western blot, homologous recombination (HR) and non-homologous end joining (NHEJ) reporter, immunofluorescence, and comet assays. Orthotopic murine models were used to study efficacy in vivo.
RESULTS
TCGA analysis showed KDM1A is highly expressed in TMZ-treated GBM patients. Knockdown or knockout or inhibition of KDM1A enhanced TMZ efficacy in reducing the viability and self-renewal of GSCs. Pharmacokinetic studies established that NCD38 readily crosses the blood-brain barrier. CUT&Tag-seq studies showed that KDM1A is enriched at the promoters of DNA repair genes and RNA-seq studies confirmed that KDM1A inhibition reduced their expression. Knockdown or inhibition of KDM1A attenuated HR and NHEJ-mediated DNA repair capacity and enhanced TMZ-mediated DNA damage. A combination of KDM1A knockdown or inhibition and TMZ treatment significantly enhanced the survival of tumor-bearing mice.
CONCLUSIONS
Our results provide evidence that KDM1A inhibition sensitizes GBM to TMZ via attenuation of DNA DSB repair pathways.
Topics: Animals; Mice; Temozolomide; Glioblastoma; Lysine; DNA Breaks, Double-Stranded; Tandem Mass Spectrometry; Cell Line, Tumor; Glioma; DNA Repair; DNA; Histone Demethylases; Drug Resistance, Neoplasm; Antineoplastic Agents, Alkylating; Brain Neoplasms; Xenograft Model Antitumor Assays
PubMed: 36652263
DOI: 10.1093/neuonc/noad018 -
International Journal of Molecular... Jun 2022Glioblastoma is a fatal brain tumor with a bleak prognosis. The use of chemotherapy, primarily the alkylating agent temozolomide, coupled with radiation and surgical... (Review)
Review
Glioblastoma is a fatal brain tumor with a bleak prognosis. The use of chemotherapy, primarily the alkylating agent temozolomide, coupled with radiation and surgical resection, has provided some benefit. Despite this multipronged approach, average patient survival rarely extends beyond 18 months. Challenges to glioblastoma treatment include the identification of functional pharmacologic targets as well as identifying drugs that can cross the blood-brain barrier. To address these challenges, current research efforts are examining metabolic differences between normal and tumor cells that could be targeted. Among the metabolic differences examined to date, the apparent addiction to exogenous methionine by glioblastoma tumors is a critical factor that is not well understood and may serve as an effective therapeutic target. Others have proposed this property could be exploited by methionine dietary restriction or other approaches to reduce methionine availability. However, methionine links the tumor microenvironment with cell metabolism, epigenetic regulation, and even mitosis. Therefore methionine depletion could result in complex and potentially undesirable responses, such as aneuploidy and the aberrant expression of genes that drive tumor progression. If methionine manipulation is to be a therapeutic strategy for glioblastoma patients, it is essential that we enhance our understanding of the role of methionine in the tumor microenvironment.
Topics: Antineoplastic Agents, Alkylating; Brain Neoplasms; Epigenesis, Genetic; Glioblastoma; Humans; Methionine; Temozolomide; Tumor Microenvironment
PubMed: 35806160
DOI: 10.3390/ijms23137156 -
BMJ Case Reports Jul 2019
Topics: Aged; Antineoplastic Agents, Alkylating; Antineoplastic Agents, Immunological; Bendamustine Hydrochloride; Conjunctival Neoplasms; Humans; Lymphoma, Non-Hodgkin; Rituximab
PubMed: 31296640
DOI: 10.1136/bcr-2019-229599 -
Balkan Medical Journal Jun 2020
Topics: Antineoplastic Agents, Alkylating; Antineoplastic Agents, Immunological; Bevacizumab; Headache; Humans; Magnetic Resonance Imaging; Male; Neoplasms, Neuroepithelial; Radiotherapy; Temozolomide; Young Adult
PubMed: 32212579
DOI: 10.4274/balkanmedj.galenos.2020.2019.11.39 -
Theranostics 2023Glioblastoma is the most common and lethal brain tumor in adults. The incorporation of temozolomide (TMZ) into the standard treatment has increased the overall survival... (Review)
Review
Glioblastoma is the most common and lethal brain tumor in adults. The incorporation of temozolomide (TMZ) into the standard treatment has increased the overall survival rate of glioblastoma patients. Since then, significant advances have been made in understanding the benefits and limitations of TMZ. Among the latter, the unspecific toxicity of TMZ, poor solubility, and hydrolyzation are intrinsic characteristics, whereas the presence of the blood-brain barrier and some tumor properties, such as molecular and cellular heterogeneity and therapy resistance, have limited the therapeutic effects of TMZ in treating glioblastoma. Several reports have revealed that different strategies for TMZ encapsulation in nanocarriers overcome those limitations and have shown that they increase TMZ stability, half-life, biodistribution, and efficacy, offering the promise for future nanomedicine therapies in handling glioblastoma. In this review, we analyze the different nanomaterials used for the encapsulation of TMZ to improve its stability, blood half-life and efficacy, paying special attention to polymer- and lipid-based nanosystems. To improve TMZ drug resistance, present in up to 50% of patients, we detail TMZ combined therapeutic with i) other chemotherapies, ii) inhibitors, iii) nucleic acids, iv) photosensitizers and other nanomaterials for photodynamic therapy, photothermal therapy, and magnetic hyperthermia, v) immunotherapy, and vi) other less explored molecules. Moreover, we describe targeting strategies, such as passive targeting, active targeting to BBB endothelial cells, glioma cells, and glioma cancer stem cells, and local delivery, where TMZ has demonstrated an improved outcome. To finish our study, we include possible future research directions that could help decrease the time needed to move from bench to bedside.
Topics: Humans; Temozolomide; Glioblastoma; Endothelial Cells; Tissue Distribution; Brain Neoplasms; Cell Line, Tumor; Antineoplastic Agents, Alkylating; Drug Resistance, Neoplasm
PubMed: 37284445
DOI: 10.7150/thno.82005 -
Toxicology Letters Feb 2020Sulfur mustard and related vesicants are cytotoxic alkylating agents that cause severe damage to the respiratory tract. Injury is progressive leading, over time, to... (Review)
Review
Sulfur mustard and related vesicants are cytotoxic alkylating agents that cause severe damage to the respiratory tract. Injury is progressive leading, over time, to asthma, bronchitis, bronchiectasis, airway stenosis, and pulmonary fibrosis. As there are no specific therapeutics available for victims of mustard gas poisoning, current clinical treatments mostly provide only symptomatic relief. In this article, the long-term effects of mustards on the respiratory tract are described in humans and experimental animal models in an effort to define cellular and molecular mechanisms contributing to lung injury and disease pathogenesis. A better understanding of mechanisms underlying pulmonary toxicity induced by mustards may help in identifying potential targets for the development of effective clinical therapeutics aimed at mitigating their adverse effects.
Topics: Alkylating Agents; Animals; Chemical Warfare Agents; Humans; Lung; Lung Injury; Mustard Compounds; Pulmonary Fibrosis; Respiratory Tract Diseases
PubMed: 31698045
DOI: 10.1016/j.toxlet.2019.10.026 -
Molecules (Basel, Switzerland) Sep 2022DNA-alkylating natural products play an important role in drug development due to their significant antitumor activities. They usually show high affinity with DNA... (Review)
Review
DNA-alkylating natural products play an important role in drug development due to their significant antitumor activities. They usually show high affinity with DNA through different mechanisms with the aid of their unique scaffold and highly active functional groups. Therefore, the biosynthesis of these natural products has been extensively studied, especially the construction of their pharmacophores. Meanwhile, their producing strains have evolved corresponding self-resistance strategies to protect themselves. To further promote the functional characterization of their biosynthetic pathways and lay the foundation for the discovery and rational design of DNA alkylating agents, we summarize herein the progress of research into DNA-alkylating antitumor natural products, including their biosynthesis, modes of action, and auto-resistance mechanisms.
Topics: Alkylating Agents; Biological Products; Biosynthetic Pathways; DNA
PubMed: 36234921
DOI: 10.3390/molecules27196387 -
Current Oncology Reports Mar 2022Elderly patients with newly diagnosed glioblastoma (eGBM) carry a worse prognosis compared with their younger counterparts. eGBM garners special attention due to the... (Review)
Review
PURPOSE OF REVIEW
Elderly patients with newly diagnosed glioblastoma (eGBM) carry a worse prognosis compared with their younger counterparts. eGBM garners special attention due to the unique challenges, including increased treatment-associated toxicity, less relative benefit from aggressive therapy, medical comorbidities, and immunosuppression. The pivotal GBM trials excluded patients > 70 years old and the optimal treatment approach remains unsettled for eGBM. In this review, we analyze the historical evidence-based data for treating eGBM and discuss the future direction for managing this vulnerable population.
RECENT FINDINGS
Treatment for eGBM continues to evolve. Therapy choice is guided by performance status and presence of O6-methylguanine-DNA-methyltransferase (MGMT) promoter methylation. For eGBM with good performance status, combinatorial hypofractionated radiation therapy (hRT) and temozolomide should be recommended. For those with poor performance status, further stratification based on MGMT promoter methylation test result is recommended. Single-agent temozolomide is a viable treatment option for MGMT methylated tumors (mMGMT); in particular, those classified with receptor tyrosine kinase II methylation. hRT alone can be considered in MGMT unmethylated (uMGMT) eGBM patients. As precision oncology continues to advance, effective targeted and immunotherapy may emerge as new treatment options for eGBM. Management of elderly patients with newly diagnosed GBM carries a unique set of challenges. Progress has been made in defining the optimal therapeutic approach for these patients, but many questions remain to be answered.
Topics: Aged; Antineoplastic Agents, Alkylating; Brain Neoplasms; DNA Methylation; Glioblastoma; Humans; Precision Medicine; Prognosis; Temozolomide
PubMed: 35122621
DOI: 10.1007/s11912-022-01201-7