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Chemistry (Weinheim An Der Bergstrasse,... Sep 2018Mitomycin C (MC), an antitumor drug, and decarbamoylmitomycin C (DMC), a derivative of MC, alkylate DNA and form deoxyguanosine monoadducts and interstrand crosslinks...
Mitomycin C (MC), an antitumor drug, and decarbamoylmitomycin C (DMC), a derivative of MC, alkylate DNA and form deoxyguanosine monoadducts and interstrand crosslinks (ICLs). Interestingly, in mammalian culture cells, MC forms primarily deoxyguanosine adducts with a 1"-R stereochemistry at the guanine-mitosene bond (1"-α) whereas DMC forms mainly adducts with a 1"-S stereochemistry (1"-β). The molecular basis for the stereochemical configuration exhibited by DMC has been investigated using biomimetic synthesis. Here, we present the results of our studies on the monoalkylation of DNA by DMC. We show that the formation of 1"-β-deoxyguanosine adducts requires bifunctional reductive activation of DMC, and that monofunctional activation only produces 1"-α-adducts. The stereochemistry of the deoxyguanosine adducts formed is also dependent on the regioselectivity of DNA alkylation and on the overall DNA CG content. Additionally, we found that temperature plays a determinant role in the regioselectivity of duplex DNA alkylation by mitomycins: At 0 °C, both deoxyadenosine (dA) and deoxyguanosine (dG) alkylation occur whereas at 37 °C, mitomycins alkylate dG preferentially. The new reaction protocols developed in our laboratory to investigate DMC-DNA alkylation raise the possibility that oligonucleotides containing DMC 1"-β-deoxyguanosine adducts at a specific site may be synthesized by a biomimetic approach.
Topics: Alkylation; Animals; Base Sequence; Chromatography, High Pressure Liquid; DNA; DNA Adducts; DNA, Bacterial; Deoxyadenosines; Deoxyguanosine; Mice; Micrococcus luteus; Mitomycin; Mitomycins; Stereoisomerism; Temperature
PubMed: 29958326
DOI: 10.1002/chem.201802038 -
Clinical Cancer Research : An Official... Apr 2021Cancers with DNA repair dysfunction are vulnerable to DNA-damaging agents that invoke a requirement for the disabled repair mechanism. Genome sequencing, coupled with a...
Cancers with DNA repair dysfunction are vulnerable to DNA-damaging agents that invoke a requirement for the disabled repair mechanism. Genome sequencing, coupled with a detailed understanding of mechanisms of DNA repair, has accelerated the discovery of pathway-selective agents that target DNA repair deficiencies in a tumor tissue agnostic manner..
Topics: Antineoplastic Agents, Alkylating; DNA Repair; Humans; Neoplasms; Poly(ADP-ribose) Polymerase Inhibitors; Sesquiterpenes
PubMed: 33472911
DOI: 10.1158/1078-0432.CCR-20-4708 -
Angewandte Chemie (International Ed. in... Jul 2016Our cells contain common molecules, such as water or oxygen, that can damage DNA. In his studies Tomas Lindahl has shown how specific repair enzymes remove and replace... (Review)
Review
Our cells contain common molecules, such as water or oxygen, that can damage DNA. In his studies Tomas Lindahl has shown how specific repair enzymes remove and replace damaged parts of DNA in a process of vital importance.
Topics: Alkylating Agents; DNA; DNA Damage; DNA Glycosylases; DNA Methylation; DNA Repair; S-Adenosylmethionine
PubMed: 27220039
DOI: 10.1002/anie.201602159 -
Molecular Biology Reports Oct 2014Temozolomide (TMZ) is an alkylating agent that is widely used in chemotherapy for cancer. A key mechanism of resistance to TMZ is the overexpression of... (Review)
Review
Temozolomide (TMZ) is an alkylating agent that is widely used in chemotherapy for cancer. A key mechanism of resistance to TMZ is the overexpression of O(6)-methylguanine-DNA methyltransferase (MGMT). MGMT specifically repairs the DNA O(6)-methylation damage induced by TMZ and irreversibly inactivates TMZ. Regulation of MGMT expression and research regarding the mechanism of TMZ resistance will help rationalize the clinical use of TMZ. In this review, we provide an overview of recent advances in the field, with particular emphasis on MGMT structure, function, expression regulation, and the association between MGMT and resistance to TMZ.
Topics: Animals; Antineoplastic Agents, Alkylating; DNA Methylation; Dacarbazine; Drug Resistance, Neoplasm; Gene Expression; Gene Expression Regulation, Neoplastic; Humans; Neoplasms; O(6)-Methylguanine-DNA Methyltransferase; Promoter Regions, Genetic; Research; Temozolomide
PubMed: 24990698
DOI: 10.1007/s11033-014-3549-z -
Mini Reviews in Medicinal Chemistry 2016O(6)-Methylguanine-DNA-methyltransferase (MGMT) is an antimutagenic DNA repair protein highly expressed in human brain tumors. Because MGMT repairs the mutagenic,... (Review)
Review
O(6)-Methylguanine-DNA-methyltransferase (MGMT) is an antimutagenic DNA repair protein highly expressed in human brain tumors. Because MGMT repairs the mutagenic, carcinogenic and cytotoxic O(6)-alkylguanine adducts, including those generated by the clinically used anticancer alkylating agents, it has emerged as a central and rational target for overcoming tumor resistance to alkylating agents. Although the pseudosubstrates for MGMT [O(6)-benzylguanine, O(6)-(4- bromothenyl)guanine] have gained attention as powerful and clinically-relevant inhibitors, bone marrow suppression due to excessive alkylation damage has diminished this strategy. Our laboratory has been working on various posttranslational modifications of MGMT that affect its protein stability, DNA repair activity and response to oxidative stress. While these modifications greatly impact the physiological regulation of MGMT, they also highlight the opportunities for inactivating DNA repair and new drug discovery in this specific area. This review briefly describes the newer aspects of MGMT posttranslational regulation by ubiquitination, sumoylation and glutathionylation and reveals how the reactivity of the active site Cys145 can be exploited for potent inhibition and depletion of MGMT by thiol-reacting drugs such as the disulfiram and various dithiocarbamate derivatives. The possible repurposing of these nontoxic and safe drugs for improved therapy of pediatric and adult brain tumors is discussed.
Topics: Animals; Antineoplastic Agents, Alkylating; Brain; Brain Neoplasms; Cysteine; DNA Repair; Drug Discovery; Glutathione; Humans; Models, Molecular; Molecular Targeted Therapy; O(6)-Methylguanine-DNA Methyltransferase; Oxidative Stress; Protein Processing, Post-Translational
PubMed: 26202203
DOI: 10.2174/1389557515666150722101046 -
Chemical Research in Toxicology Sep 2020The cellular outcomes of chemical exposure are as much about the cellular to the chemical as it is an of the chemical. We are growing in our understanding of the... (Review)
Review
The cellular outcomes of chemical exposure are as much about the cellular to the chemical as it is an of the chemical. We are growing in our understanding of the genotoxic interaction between chemistry and biology. For example, recent data has revealed the biological basis for mutation induction curves for a methylating chemical, which has been shown to be dependent on the repair capacity of the cells. However, this is just one end point in the toxicity pathway from chemical exposure to cell death. Much remains to be known in order for us to predict how cells will respond to a certain dose. Methylating agents, a subset of alkylating agents, are of particular interest, because of the variety of adverse genetic end points that can result, not only at increasing doses, but also over time. For instance, methylating agents are mutagenic, their potency, for this end point, is determined by the cellular repair capacity of an enzyme called methylguanine DNA-methyltransferase (MGMT) and its ability to repair the induceed methyl adducts. However, methyl adducts can become clastogenic. Erroneous biological processing will convert mutagenic adducts to clastogenic events in the form of double strand breaks (DSBs). How the cell responds to DSBs is via a cascade of protein kinases, which is called the DNA damage response (DDR), which will determine if the damage is repaired effectively, via homologous recombination, or with errors, via nonhomologous end joining, or whether the cell dies via apoptosis or enters senescence. The fate of cells may be determined by the extent of damage and the resulting strength of DDR signaling. Therefore, thresholds of damage may exist that determine cell fate. Such thresholds would be dependent on each of the repair and response mechanisms that these methyl adducts stimulate. The molecular mechanism of how methyl adducts kill cells is still to be fully resolved. If we are able to quantify each of these thresholds of damage for a given cell, then we can ascertain, of the many adducts that are induced, what proportion of them are mutagenic, what proportion are clastogenic, and how many of these clastogenic events are toxic. This review examines the possibility of dose and damage thresholds for methylating agents, from the perspective of the underlying evolutionary mechanisms that may be accountable.
Topics: Alkylating Agents; Animals; Enzyme Inhibitors; Humans; Methylation; O(6)-Methylguanine-DNA Methyltransferase
PubMed: 32388971
DOI: 10.1021/acs.chemrestox.0c00052 -
Oncotarget May 2023
Topics: Humans; Temozolomide; Glioblastoma; DNA Repair; Dacarbazine; Autophagy; DNA Modification Methylases; DNA Repair Enzymes; Antineoplastic Agents, Alkylating; Brain Neoplasms; Drug Resistance, Neoplasm; GTP-Binding Proteins
PubMed: 37204260
DOI: 10.18632/oncotarget.28370 -
CNS Neuroscience & Therapeutics Apr 2024To elucidate the relationship between USP19 and O(6)-methylguanine-DNA methyltransferase (MGMT) after temozolomide treatment in glioblastoma (GBM) patients with...
OBJECTIVE
To elucidate the relationship between USP19 and O(6)-methylguanine-DNA methyltransferase (MGMT) after temozolomide treatment in glioblastoma (GBM) patients with chemotherapy resistance.
METHODS
Screening the deubiquitinase pannel and identifying the deubiquitinase directly interacts with and deubiquitination MGMT. Deubiquitination assay to confirm USP19 deubiquitinates MGMT. The colony formation and tumor growth study in xenograft assess USP19 affects the GBM sensitive to TMZ was performed by T98G, LN18, U251, and U87 cell lines. Immunohistochemistry staining and survival analysis were performed to explore how USP19 is correlated to MGMT in GBM clinical management.
RESULTS
USP19 removes the ubiquitination of MGMT to facilitate the DNA methylation damage repair. Depletion of USP19 results in the glioblastoma cell sensitivity to temozolomide, which can be rescued by overexpressing MGMT. USP19 is overexpressed in glioblastoma patient samples, which positively correlates with the level of MGMT protein and poor prognosis in these patients.
CONCLUSION
The regulation of MGMT ubiquitination by USP19 plays a critical role in DNA methylation damage repair and GBM patients' temozolomide chemotherapy response.
Topics: Humans; Temozolomide; DNA Repair Enzymes; DNA Modification Methylases; Antineoplastic Agents, Alkylating; Animals; Cell Line, Tumor; Drug Resistance, Neoplasm; Tumor Suppressor Proteins; DNA Methylation; Mice, Nude; Brain Neoplasms; Glioblastoma; Mice; Male; Female; Dacarbazine; DNA Repair; Endopeptidases; Xenograft Model Antitumor Assays; Ubiquitination
PubMed: 38644551
DOI: 10.1111/cns.14711 -
-alkylguanine-DNA Alkyltransferases in Microbes Living on the Edge: From Stability to Applicability.International Journal of Molecular... Apr 2020The genome of living cells is continuously exposed to endogenous and exogenous attacks, and this is particularly amplified at high temperatures. Alkylating agents cause... (Review)
Review
The genome of living cells is continuously exposed to endogenous and exogenous attacks, and this is particularly amplified at high temperatures. Alkylating agents cause DNA damage, leading to mutations and cell death; for this reason, they also play a central role in chemotherapy treatments. A class of enzymes known as AGTs (alkylguanine-DNA-alkyltransferases) protects the DNA from mutations caused by alkylating agents, in particular in the recognition and repair of alkylated guanines in -position. The peculiar irreversible self-alkylation reaction of these enzymes triggered numerous studies, especially on the human homologue, in order to identify effective inhibitors in the fight against cancer. In modern biotechnology, engineered variants of AGTs are developed to be used as for the attachment of chemical ligands. In the last decade, research on AGTs from (hyper)thermophilic sources proved useful as a model system to clarify numerous phenomena, also common for mesophilic enzymes. This review traces recent progress in this class of , emphasizing their usefulness in basic research and their consequent advantages for in vivo and in vitro biotechnological applications.
Topics: Alkylation; Biotechnology; DNA Damage; DNA Repair; DNA Replication; Molecular Targeted Therapy; Neoplasms; O(6)-Methylguanine-DNA Methyltransferase; Structure-Activity Relationship; Thermodynamics; Thermoproteus
PubMed: 32326075
DOI: 10.3390/ijms21082878 -
Organic Letters Dec 2022DNA-encoded library (DEL) screens have become a key technology to find small molecule binders to biological targets for drug discovery applications. The development of...
DNA-encoded library (DEL) screens have become a key technology to find small molecule binders to biological targets for drug discovery applications. The development of new DNA-compatible chemistries to expand the accessible DEL chemical space is imperative to enhance screen success across broad target classes and modalities. Additionally, reactions that use commonly available building blocks as well as those that enable the fsp of library members to be increased would have high impact for accessing diverse drug-like structures. Herein, we report a DNA-compatible Giese-type addition of nonstabilized C-centered radicals generated by the deoxygenation of preactivated alcohols into on-DNA olefins. Although alcohols have been historically underused as a building block class within DEL synthesis, their activation to a xanthate enables Csp-Csp coupling to furnish sp-rich products. This reaction is compatible with multiple classes of functional groups, does not damage the DNA tag, and is suitable for use in DEL productions.
Topics: Alcohols; Alkenes; Alkylation; DNA; Oxidation-Reduction; Indicators and Reagents
PubMed: 36541781
DOI: 10.1021/acs.orglett.2c03994