-
Brain : a Journal of Neurology Mar 2024Parkinson's disease (PD) is a neurodegenerative disorder primarily known for typical motor features that arise due to the loss of dopaminergic neurons in the substantia...
Parkinson's disease (PD) is a neurodegenerative disorder primarily known for typical motor features that arise due to the loss of dopaminergic neurons in the substantia nigra. However, the precise molecular etiology of the disease is still unclear. Several cellular pathways have been linked to PD, including the autophagy-lysosome pathway (ALP), α-synuclein (α-syn) aggregation, and mitochondrial function. Interestingly, the mechanistic link between GBA1, the gene that encodes for lysosomal β-glucocerebrosidase (GCase), and PD lies in the interplay between GCase functions in the lysosome and mitochondria. GCase mutations alter mitochondria-lysosome contact sites. In the lysosome, reduced GCase activity leads to glycosphingolipid buildup, disrupting lysosomal function and autophagy, thereby triggering α-syn accumulation. Additionally, α-syn aggregates reduce GCase activity, creating a self-perpetuating cycle of lysosomal dysfunction and α-syn accumulation. GCase can also be imported into the mitochondria, where it promotes the integrity and function of mitochondrial complex I. Thus, GCase mutations that impair its normal function increase oxidative stress in mitochondria, the compartment where dopamine is oxidized. In turn, the accumulation of oxidized dopamine-adducts further impairs GCase activity, creating a second cycle of GCase dysfunction. The oxidative state triggered by GCase dysfunction can also induce mitochondrial DNA damage which, in turn, can cause dopaminergic cell death. In this review, we highlight the pivotal role of GCase in PD pathogenesis and discuss promising examples of GCase-based therapeutics such as gene and enzyme replacement therapies, small molecule chaperones, and substrate reduction therapies, among others, as potential therapeutic interventions.
PubMed: 38437875
DOI: 10.1093/brain/awae070 -
ACS Chemical Biology Jun 2024Methylglyoxal (MGO) is an electrophilic α-oxoaldehyde generated endogenously through metabolism of carbohydrates and exogenously due to autoxidation of sugars,...
Methylglyoxal (MGO) is an electrophilic α-oxoaldehyde generated endogenously through metabolism of carbohydrates and exogenously due to autoxidation of sugars, degradation of lipids, and fermentation during food and drink processing. MGO can react with nucleophilic sites within proteins and DNA to form covalent adducts. MGO-induced advanced glycation end-products such as protein and DNA adducts are thought to be involved in oxidative stress, inflammation, diabetes, cancer, renal failure, and neurodegenerative diseases. Additionally, MGO has been hypothesized to form toxic DNA-protein cross-links (DPC), but the identities of proteins participating in such cross-linking in cells have not been determined. In the present work, we quantified DPC formation in human cells exposed to MGO and identified proteins trapped on DNA upon MGO exposure using mass spectrometry-based proteomics. A total of 265 proteins were found to participate in MGO-derived DPC formation including gene products engaged in telomere organization, nucleosome assembly, and gene expression. experiments confirmed DPC formation between DNA and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), as well as histone proteins H3.1 and H4. Collectively, our study provides the first evidence for MGO-mediated DNA-protein cross-linking in living cells, prompting future studies regarding the relevance of these toxic lesions in cancer, diabetes, and other diseases linked to elevated MGO levels.
Topics: Pyruvaldehyde; Humans; DNA; DNA Adducts; Proteins; Proteomics
PubMed: 38752800
DOI: 10.1021/acschembio.4c00100 -
Biomedicines Nov 2023Cellular organisms possess intricate DNA damage repair and tolerance pathways to manage various DNA lesions arising from endogenous or exogenous sources. The...
Cellular organisms possess intricate DNA damage repair and tolerance pathways to manage various DNA lesions arising from endogenous or exogenous sources. The dysregulation of these pathways is associated with cancer development and progression. Synthetic lethality (SL), a promising cancer therapy concept, involves exploiting the simultaneous functional loss of two genes for selective cell death. PARP inhibitors (PARPis) have demonstrated success in BRCA-deficient tumors. Cisplatin (CPT), a widely used chemotherapy agent, forms DNA adducts and crosslinks, rendering it effective against various cancers, but less so for prostate cancer (PCa) due to resistance and toxicity. Here, we explore the therapeutic potential of TLK1, a kinase upregulated in androgen-insensitive PCa cells, as a target for enhancing CPT-based therapy. TLK1 phosphorylates key homologous recombination repair (HRR) proteins, RAD54L and RAD54B, which are critical for HRR alongside RAD51. The combination of CPT with TLK1 inhibitor J54 exhibits SL in androgen-insensitive PCa cells. The formation of double-strand break intermediates during inter-strand crosslink processing necessitates HRR for effective repair. Therefore, targeting TLK1 with J54 enhances the SL of CPT by impeding HRR, leading to increased sensitivity in PCa cells. These findings suggest a promising approach for improving CPT-based therapies in PCa, particularly in androgen-insensitive cases. By elucidating the role of TLK1 in CPT resistance, this study provides valuable insights into potential therapeutic targets to overcome PCa resistance to CPT chemotherapy. Further investigations into TLK1 inhibition in combination with other DNA-damaging agents may pave the way for more effective and targeted treatments for PCa and other cancers that exhibit resistance to traditional chemotherapy agents.
PubMed: 38001987
DOI: 10.3390/biomedicines11112987 -
The Journal of Biological Chemistry Aug 2023Acrylamide, a common food contaminant, is metabolically activated to glycidamide, which reacts with DNA at the N7 position of dG, forming...
Acrylamide, a common food contaminant, is metabolically activated to glycidamide, which reacts with DNA at the N7 position of dG, forming N7-(2-carbamoyl-2-hydroxyethyl)-dG (GAdG). Owing to its chemical lability, the mutagenic potency of GAdG has not yet been clarified. We found that GAdG undergoes ring-opening hydrolysis to form N-(2-deoxy-d-erythro-pentofuranosyl)-2,6-diamino-3,4-dihydro-4-oxo-5-[N-(2-carbamoyl-2-hydroxyethyl)formamido]pyrimidine (GA-FAPy-dG), even at neutral pH. Therefore, we aimed to examine the effects of GA-FAPy-dG on the efficiency and fidelity of DNA replication using an oligonucleotide carrying GA-FAPy-9-(2-deoxy-2-fluoro-β-d-arabinofuranosyl)guanine (dfG), a 2'-fluorine substituted analog of GA-FAPy-dG. GA-FAPy-dfG inhibited primer extension by both human replicative DNA polymerase ε and the translesion DNA synthesis polymerases (Polη, Polι, Polκ, and Polζ) and reduced the replication efficiency by less than half in human cells, with single base substitution at the site of GA-FAPy-dfG. Unlike other formamidopyrimidine derivatives, the most abundant mutation was G:C > A:T transition, which was decreased in Polκ- or REV1-KO cells. Molecular modeling suggested that a 2-carbamoyl-2-hydroxyethyl group at the N position of GA-FAPy-dfG can form an additional H-bond with thymidine, thereby contributing to the mutation. Collectively, our results provide further insight into the mechanisms underlying the mutagenic effects of acrylamide.
Topics: Humans; Acrylamides; Deoxyguanosine; DNA; DNA Adducts; DNA Damage; DNA Replication; Mutagenesis; Mutagens; Food Contamination
PubMed: 37394003
DOI: 10.1016/j.jbc.2023.105002 -
Chemico-biological Interactions Sep 2023Vitamin B (cyano- or hydroxo-cobalamin) acts, via its coenzymes, methyl- and adenosyl-cobalamin, as a partner for enzymatic reactions in humans catalysed by methionine...
Vitamin B (cyano- or hydroxo-cobalamin) acts, via its coenzymes, methyl- and adenosyl-cobalamin, as a partner for enzymatic reactions in humans catalysed by methionine synthase and methylmalonyl-CoA mutase. As well as its association with pernicious anaemia, human B deficiency may also be a risk factor for neurological illnesses, heart disease and cancer. In the present work the effect of vitamin B (hydroxocobalamin) on the formation of DNA adducts by the epoxide phenyloxirane (styrene oxide), a genotoxic metabolite of phenylethene (styrene), has been studied using an in vitro model system. Styrene was converted to its major metabolite styrene oxide as a mixture of enantiomers using a microsomal fraction from the livers of Sprague-Dawley rats with concomitant inhibition of epoxide hydrolase. However, microsomal oxidation of styrene in the presence of vitamin B gave diastereoisomeric 2-hydroxy-2-phenylcobalamins. The quantitative formation of styrene oxide-DNA adducts was investigated using 2-deoxyguanosine or calf thymus DNA in the presence or absence of vitamin B. Microsomal incubations containing either deoxyguanosine or DNA in the absence of vitamin B gave 2-amino-7-(2-hydroxy-1-phenylethyl)-1,7-dihydro-6H-purin-6-one [N7-(2-hydroxy-1-phenylethyl)-guanine], and 2-amino-7-(2-hydroxy-2-phenylethyl)-1,7-dihydro-6H-purin-6-one [N7-(2-hydroxy-2-phenylethyl)guanine] as the principal adducts. With deoxyguanosine the level of formation of guanine adducts was ca. 150 adducts/10 unmodified nucleoside. With DNA the adduct level was 36 pmol/mg DNA (ca. 1 adduct/0.83 × 10 nucleotides). Styrene oxide adducts from deoxyguanosine or DNA were not detected in microsomal incubations of styrene in the presence of vitamin B. These results suggest that vitamin B could protect DNA against genotoxicity due to styrene oxide and other xenobiotic metabolites. However, this potential defence mechanism requires that the 2-hydroxyalkylcobalamins derived from epoxides are not 'anti-vitamins' and ideally liberate, and therefore, recycle vitamin B. Otherwise, depletion of vitamin B leading to human deficiency could increase the risk of carcinogenesis initiated by genotoxic epoxides.
Topics: Animals; Rats; Humans; DNA Adducts; Vitamin B 12; Xenobiotics; Rats, Sprague-Dawley; Epoxy Compounds; DNA Damage; DNA; Guanine; Deoxyguanosine; Styrenes; Styrene
PubMed: 37302460
DOI: 10.1016/j.cbi.2023.110591 -
BioRxiv : the Preprint Server For... Jan 2024Acetaldehyde is the primary metabolite of alcohol and is present in many environmental sources including tobacco smoke. Acetaldehyde is genotoxic, whereby it can form...
Acetaldehyde is the primary metabolite of alcohol and is present in many environmental sources including tobacco smoke. Acetaldehyde is genotoxic, whereby it can form DNA adducts and lead to mutagenesis. Individuals with defects in acetaldehyde clearance pathways have increased susceptibility to alcohol-associated cancers. Moreover, a mutation signature specific to acetaldehyde exposure is widespread in alcohol and smoking-associated cancers. However, the pathways that repair acetaldehyde-induced DNA damage and thus prevent mutagenesis are vaguely understood. Here, we used to systematically delete genes in each of the major DNA repair pathways to identify those that alter acetaldehyde-induced mutagenesis. We found that deletion of the nucleotide excision repair (NER) genes, or , led to an increase in mutagenesis upon acetaldehyde exposure. Acetaldehyde-induced mutations were dependent on translesion synthesis as well as DNA inter-strand crosslink (ICL) repair in strains. Moreover, whole genome sequencing of the mutated isolates demonstrated an increase in C→A changes coupled with an enrichment of gCn→A changes in the acetaldehyde-treated isolates. The gCn→A mutation signature has been shown to be diagnostic of acetaldehyde exposure in yeast and in human cancers. We also demonstrated that the deletion of the two DNA-protein crosslink (DPC) repair proteases, and , also led to increased acetaldehyde-induced mutagenesis. Defects in base excision repair (BER) led to a mild increase in mutagenesis, while defects in mismatch repair (MMR), homologous recombination repair (HR) and post replicative repair pathways did not impact mutagenesis upon acetaldehyde exposure. Our results in yeast were further corroborated upon analysis of whole exome sequenced liver cancers, wherein, tumors with defects in ERCC1 and ERCC4 (NER), FANCD2 (ICL repair) or SPRTN (DPC repair) carried a higher gCn→A mutation load than tumors with no deleterious mutations in these genes. Our findings demonstrate that multiple DNA repair pathways protect against acetaldehyde-induced mutagenesis.
PubMed: 38260495
DOI: 10.1101/2024.01.07.574575 -
International Journal of Molecular... Jul 2023Glioblastoma multiforme (GBM) has high mortality and recurrence rates. Malignancy resilience is ascribed to Glioblastoma Stem Cells (GSCs), which are resistant to...
Glioblastoma multiforme (GBM) has high mortality and recurrence rates. Malignancy resilience is ascribed to Glioblastoma Stem Cells (GSCs), which are resistant to Temozolomide (TMZ), the gold standard for GBM post-surgical treatment. However, Nitric Oxide (NO) has demonstrated anti-cancer efficacy in GBM cells, but its potential impact on GSCs remains unexplored. Accordingly, we investigated the effects of NO, both alone and in combination with TMZ, on patient-derived GSCs. Experimentally selected concentrations of diethylenetriamine/NO adduct and TMZ were used through a time course up to 21 days of treatment, to evaluate GSC proliferation and death, functional recovery, and apoptosis. Immunofluorescence and Western blot analyses revealed treatment-induced effects in cell cycle and DNA damage occurrence and repair. Our results showed that NO impairs self-renewal, disrupts cell-cycle progression, and expands the quiescent cells' population. Consistently, NO triggered a significant but tolerated level of DNA damage, but not apoptosis. Interestingly, NO/TMZ cotreatment further inhibited cell cycle progression, augmented G0 cells, induced cell death, but also enhanced DNA damage repair activity. These findings suggest that, although NO administration does not eliminate GSCs, it stunts their proliferation, and makes cells susceptible to TMZ. The resulting cytostatic effect may potentially allow long-term control over the GSCs' subpopulation.
Topics: Humans; Temozolomide; Glioblastoma; Nitric Oxide; Dacarbazine; Cell Line, Tumor; Cell Proliferation; Cell Cycle; Stem Cells; Brain Neoplasms; Drug Resistance, Neoplasm; Neoplastic Stem Cells; Antineoplastic Agents, Alkylating
PubMed: 37511047
DOI: 10.3390/ijms241411286 -
Scientific Reports Jul 2023Nicotine is a highly addictive alkaloid and a neurostimulator found in tobacco that causes addiction in humans and makes tobacco a high-demand commercial product. It is...
Nicotine is a highly addictive alkaloid and a neurostimulator found in tobacco that causes addiction in humans and makes tobacco a high-demand commercial product. It is popularly used for recreational purposes and is a harmful substance (Oral LD value for rat is 50 mg/kg) and causes addiction. The metabolites of nicotine such as the Tobacco-specific Nitrosamines (TSNAs) are hazardous substances whose metabolites are highly electrophilic and form DNA adducts, which will initiate the process of carcinogenesis. TSNAs are formed during curing, storage and fermentation due to the nitrosation of nicotine and other tobacco alkaloids. TSNAs are used as biomarkers for cancer risk assessment in humans exposed to tobacco and its products. To determine the occasional formation of TSNAs in tobacco-feeding insects, 5th instar larvae of Spodoptera litura and their faeces were analyzed for the presence of N'-nitrosonornicotine (NNN), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) along with the stored tobacco leaves (PT-76) using an Agilent 6470B LC-MS/MS system following ISO/DIS 19290:2015 protocol. The larvae are extracted in a buffered acetonitrile-water extraction and the amount of TSNAs are quantified in multiple reaction monitoring (MRM) mode. 20 [Formula: see text]l of each extracted and cleaned up sample was injected into the LC-MS/MS system for quantification. The Limit of Detection (LOD) and Limit of Quantification (LOQ) were 0.001 mg/kg and 0.005 mg/kg for all the tested nitrosamines. NNN was found to be 0.361 mg/kg, 0.340 mg/kg, and 5.66 mg/kg in insect whole-body samples, faeces, and tobacco leaves, respectively. NNK was found to be 0.060 mg/kg, 0.035 mg/kg and 0.93 mg/kg in insect whole body samples, faeces and tobacco leaves, respectively. However, NNAL was not detected in both the insect's whole body and faeces. Recoveries ranged between 95 and 98% for all compounds when spiked at LOD and LOQ. The presence of TSNAs is a biomarker for cancer risk and their presence in insects would point to cancer risk assessment in tobacco feeding insects and any possible TSNA-detoxifying pathways in insects that might prevent mutagenesis caused these compounds.
Topics: Humans; Animals; Rats; Nicotine; Spodoptera; Chromatography, Liquid; Tandem Mass Spectrometry; Nitrosamines; Carcinogenesis; Alkaloids; Biomarkers; Carcinogens
PubMed: 37500666
DOI: 10.1038/s41598-023-37656-2 -
Journal of Medicinal Chemistry Dec 2023WD40 repeat-containing protein 91 (WDR91) regulates early-to-late endosome conversion and plays vital roles in endosome fusion, recycling, and transport. WDR91 was...
WD40 repeat-containing protein 91 (WDR91) regulates early-to-late endosome conversion and plays vital roles in endosome fusion, recycling, and transport. WDR91 was recently identified as a potential host factor for viral infection. We employed DNA-encoded chemical library (DEL) selection against the WDR domain of WDR91, followed by machine learning to predict ligands from the synthetically accessible Enamine REAL database. Screening of predicted compounds identified a WDR91 selective compound , with a of 6 ± 2 μM by surface plasmon resonance. The co-crystal structure confirmed the binding of to the WDR91 side pocket, in proximity to cysteine 487, which led to the discovery of covalent analogues and . The covalent adduct formation for and was confirmed by intact mass liquid chromatography-mass spectrometry. The discovery of , , and , accompanying structure-activity relationship, and the co-crystal structures provide valuable insights for designing potent and selective chemical tools against WDR91 to evaluate its therapeutic potential.
Topics: DNA; Gene Library; Ligands; Machine Learning; Small Molecule Libraries
PubMed: 37996079
DOI: 10.1021/acs.jmedchem.3c01471 -
Environmental Pollution (Barking, Essex... Jun 2024Urbanization has numerous benefits to human society, but some aspects of urban environments, such as air pollution, can negatively affect human health. Two major air... (Meta-Analysis)
Meta-Analysis Review
Urbanization has numerous benefits to human society, but some aspects of urban environments, such as air pollution, can negatively affect human health. Two major air pollutants, particulate matter (PM) and polycyclic aromatic hydrocarbons (PAH), have been classified as carcinogens by the International Agency for Research on Cancer. Here, we answer two questions: (1) What are the carcinogenic effects of PM and PAH exposure? (2) How does carcinogenic risk vary across geographical regions? We performed a comprehensive literature search of peer-reviewed published studies examining the link between air pollution and human cancer rates. Focusing on studies published since 2014 when the last IARC monograph on air pollution was published, we converted the extracted data into relative risks and performed subgroup analyses. Exposure to PM (per 10 μg/m) resulted in an 8.5% increase in cancer incidence when all cancer types were combined, and risk for individual cancer types (i.e. lung cancer and adenocarcinoma) was also elevated. PM was also associated with 2.5% higher mortality due to cancer when all types of cancer were combined, and for individual cancer types (i.e., lung and breast cancer). Exposure to PM and PM posed the greatest risk to lung cancer incidence and mortality in Europe (PM RR 2.15; PM RR 1.26); the risk in Asia and the Americas was also elevated. Exposure to PAH and benzo[a]pyrene significantly increased the pooled risk of cancer incidence (10.8% and 8.0% respectively) at the highest percentile of exposure concentration. Our meta-analyses of studies over the past decade shows that urban air pollution in the form of PM, PM, and PAH all elevate the incidence and mortality of cancer. We discuss the possible mechanisms of carcinogenesis of PM and PAH. These results support World Health Organization's conclusion that air pollution poses among the greatest health risks to humans living in cities.
Topics: Humans; Air Pollutants; Air Pollution; Carcinogens; Environmental Exposure; Neoplasms; Particulate Matter; Polycyclic Aromatic Hydrocarbons
PubMed: 38614427
DOI: 10.1016/j.envpol.2024.123941