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International Journal of Molecular... Nov 2023Cisplatin is a commonly used chemotherapeutic agent with proven efficacy in treating various malignancies, including testicular, ovarian, cervical, breast, bladder, head... (Review)
Review
Cisplatin is a commonly used chemotherapeutic agent with proven efficacy in treating various malignancies, including testicular, ovarian, cervical, breast, bladder, head and neck, and lung cancer. Cisplatin is also used to treat tumors in children, such as neuroblastoma, osteosarcoma, and hepatoblastoma. However, its clinical use is limited by severe side effects, including ototoxicity, nephrotoxicity, neurotoxicity, hepatotoxicity, gastrointestinal toxicity, and retinal toxicity. Cisplatin-induced ototoxicity manifests as irreversible, bilateral, high-frequency sensorineural hearing loss in 40-60% of adults and in up to 60% of children. Hearing loss can lead to social isolation, depression, and cognitive decline in adults, and speech and language developmental delays in children. Cisplatin causes hair cell death by forming DNA adducts, mitochondrial dysfunction, oxidative stress, and inflammation, culminating in programmed cell death by apoptosis, necroptosis, pyroptosis, or ferroptosis. Contemporary medical interventions for cisplatin ototoxicity are limited to prosthetic devices, such as hearing aids, but these have significant limitations because the cochlea remains damaged. Recently, the U.S. Food and Drug Administration (FDA) approved the first therapy, sodium thiosulfate, to prevent cisplatin-induced hearing loss in pediatric patients with localized, non-metastatic solid tumors. Other pharmacological treatments for cisplatin ototoxicity are in various stages of preclinical and clinical development. This narrative review aims to highlight the molecular mechanisms involved in cisplatin-induced ototoxicity, focusing on cochlear inflammation, and shed light on potential antioxidant and anti-inflammatory therapeutic interventions to prevent or mitigate the ototoxic effects of cisplatin. We conducted a comprehensive literature search (Google Scholar, PubMed) focusing on publications in the last five years.
Topics: Humans; Child; Cisplatin; Antineoplastic Agents; Ototoxicity; Hearing Loss; Osteosarcoma; Deafness; Bone Neoplasms; Inflammation
PubMed: 38003734
DOI: 10.3390/ijms242216545 -
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 -
Nucleic Acids Research Jan 2024Although ubiquitylation had traditionally been considered limited to proteins, the discovery of non-proteinaceous substrates (e.g. lipopolysaccharides and adenosine...
Although ubiquitylation had traditionally been considered limited to proteins, the discovery of non-proteinaceous substrates (e.g. lipopolysaccharides and adenosine diphosphate ribose (ADPr)) challenged this perspective. Our recent study showed that DTX2 E3 ligase efficiently ubiquitylates ADPr. Here, we show that the ADPr ubiquitylation activity is also present in another DELTEX family member, DTX3L, analysed both as an isolated catalytic fragment and the full-length PARP9:DTX3L complex, suggesting that it is a general feature of the DELTEX family. Since structural predictions show that DTX3L possesses single-stranded nucleic acids binding ability and given the fact that nucleic acids have recently emerged as substrates for ADP-ribosylation, we asked whether DELTEX E3s might catalyse ubiquitylation of an ADPr moiety linked to nucleic acids. Indeed, we show that DTX3L and DTX2 are capable of ubiquitylating ADP-ribosylated DNA and RNA synthesized by PARPs, including PARP14. Furthermore, we demonstrate that the Ub-ADPr-nucleic acids conjugate can be reversed by two groups of hydrolases, which remove either the whole adduct (e.g. SARS-CoV-2 Mac1 or PARP14 macrodomain 1) or just the Ub (e.g. SARS-CoV-2 PLpro). Overall, this study reveals ADPr ubiquitylation as a general function of the DELTEX family E3s and presents the evidence of reversible ubiquitylation of ADP-ribosylated nucleic acids.
Topics: Adenosine Diphosphate Ribose; ADP-Ribosylation; Nucleic Acids; Okadaic Acid; Proteins; Ubiquitin-Protein Ligases; Humans
PubMed: 38000390
DOI: 10.1093/nar/gkad1119 -
Cells Nov 2023Duplication of the genome requires the replication apparatus to overcome a variety of impediments, including covalent DNA adducts, the most challenging of which is on... (Review)
Review
Duplication of the genome requires the replication apparatus to overcome a variety of impediments, including covalent DNA adducts, the most challenging of which is on the leading template strand. Replisomes consist of two functional units, a helicase to unwind DNA and polymerases to synthesize it. The helicase is a multi-protein complex that encircles the leading template strand and makes the first contact with a leading strand adduct. The size of the channel in the helicase would appear to preclude transit by large adducts such as DNA: protein complexes (DPC). Here we discuss some of the extensively studied pathways that support replication restart after replisome encounters with leading template strand adducts. We also call attention to recent work that highlights the tolerance of the helicase for adducts ostensibly too large to pass through the central channel.
Topics: DNA Replication; DNA Helicases; DNA
PubMed: 37998342
DOI: 10.3390/cells12222607 -
Chemical Research in Toxicology Dec 2023The genotoxic 3-(2-deoxy-β-D-erythro-pentofuranosyl)pyrimido[1,2-α]purin-10(3H)-one (MdG) DNA lesion arises from endogenous exposures to base propenals generated by...
The genotoxic 3-(2-deoxy-β-D-erythro-pentofuranosyl)pyrimido[1,2-α]purin-10(3H)-one (MdG) DNA lesion arises from endogenous exposures to base propenals generated by oxidative damage and from exposures to malondialdehyde (MDA), produced by lipid peroxidation. Once formed, MdG may oxidize, , to 3-(2-deoxy-β-D-erythropentofuranosyl)-pyrimido[1,2-]purine-6,10(3,5)-dione (6-oxo-MdG). The latter blocks DNA replication and is a substrate for error-prone mutagenic bypass by the Y-family DNA polymerase hpol η. To examine structural consequences of 6-oxo-MdG damage in DNA, we conducted NMR studies of 6-oxo-MdG incorporated site-specifically into 5' -d(CATATGACGCT)-3':5'-d(AGCGTCATCATG)-3' ( = 6-oxo-MdG). NMR spectra afforded detailed resonance assignments. Chemical shift analyses revealed that nucleobase C, complementary to 6-oxo-MdG, was deshielded compared with the unmodified duplex. Sequential NOEs between 6-oxo-MdG and A were disrupted, as well as NOEs between T and C in the complementary strand. The structure of the 6-oxo-MdG modified DNA duplex was refined by using molecular dynamics (rMD) calculations restrained by NOE data. It revealed that 6-oxo-MdG intercalated into the duplex and remained in the -conformation about the glycosyl bond. The complementary cytosine C extruded into the major groove, accommodating the intercalated 6-oxo-MdG. The 6-oxo-MdG H7 and H8 protons faced toward the major groove, while the 6-oxo-MdG imidazole proton H2 faced into the major groove. Structural perturbations to dsDNA were limited to the 6-oxo-MdG damaged base pair and the flanking T:A and A:T base pairs. Both neighboring base pairs remained within the Watson-Crick hydrogen bonding contact. The 6-oxo-MdG did not stack well with the 5'-neighboring base pair T:A but showed improved stacking with the 3'-neighboring base pair A:T. Overall, the base-displaced intercalated structure was consistent with thermal destabilization of the 6-oxo-MdG damaged DNA duplex; thermal melting temperature data showed a 15 °C decrease in compared to the unmodified duplex. The structural consequences of 6-oxo-MdG formation in DNA are evaluated in the context of the chemical biology of this lesion.
Topics: DNA Adducts; DNA; Purines; DNA Damage; Molecular Conformation; Protons; Nucleic Acid Conformation; Deoxyguanosine
PubMed: 37989274
DOI: 10.1021/acs.chemrestox.3c00226 -
Chemical Research in Toxicology Dec 2023Human exposure to DNA alkylating agents is poorly characterized, partly because only a limited range of specific alkyl DNA adducts have been quantified. The human DNA...
Mass Spectrometric Analysis of the Active Site Tryptic Peptide of Recombinant -Methylguanine-DNA Methyltransferase Following Incubation with Human Colorectal DNA Reveals the Presence of an -Alkylguanine Adductome.
Human exposure to DNA alkylating agents is poorly characterized, partly because only a limited range of specific alkyl DNA adducts have been quantified. The human DNA repair protein, -methylguanine -methyltransferase (MGMT), irreversibly transfers the alkyl group from DNA -alkylguanines (-alkGs) to an acceptor cysteine, allowing the simultaneous detection of multiple -alkG modifications in DNA by mass spectrometric analysis of the MGMT active site peptide (ASP). Recombinant MGMT was incubated with oligodeoxyribonucleotides (ODNs) containing different -alkGs, Temozolomide-methylated calf thymus DNA (Me-CT-DNA), or human colorectal DNA of known -MethylG (-MeG) levels. It was digested with trypsin, and ASPs were detected and quantified by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry. ASPs containing -methyl, -ethyl, -propyl, -hydroxyethyl, -carboxymethyl, -benzyl, and -pyridyloxobutyl cysteine groups were detected by incubating MGMT with ODNs containing the corresponding -alkGs. The LOQ of ASPs containing -methylcysteine detected after MGMT incubation with Me-CT-DNA was <0.05 pmol -MeG per mg CT-DNA. Incubation of MGMT with human colorectal DNA produced ASPs containing -methylcysteine at levels that correlated with those of -MeG determined previously by HPLC-radioimmunoassay ( = 0.74; p = 0.014). -CMG, a putative -hydroxyethylG adduct, and other potential unidentified MGMT substrates were also detected in human DNA samples. This novel approach to the identification and quantitation of -alkGs in human DNA has revealed the existence of a human DNA alkyl adductome that remains to be fully characterized. The methodology establishes a platform for characterizing the human DNA -alkG adductome and, given the mutagenic potential of -alkGs, can provide mechanistic information about cancer pathogenesis.
Topics: Humans; Catalytic Domain; Colorectal Neoplasms; Cysteine; DNA; DNA Repair; Mass Spectrometry; O(6)-Methylguanine-DNA Methyltransferase; Oligodeoxyribonucleotides; Peptides
PubMed: 37983188
DOI: 10.1021/acs.chemrestox.3c00207 -
Stem Cells (Dayton, Ohio) Feb 2024Hematopoietic stem cells (HSC) from cord blood can be applied as an alternative to bone marrow in transplantation to treat hematological diseases. Umbilical cord blood...
Hematopoietic stem cells (HSC) from cord blood can be applied as an alternative to bone marrow in transplantation to treat hematological diseases. Umbilical cord blood (UCB) consists of cycling and non-cycling CD34+/CD45low cells needed for long-term and short-term engraftment. After sorting and subsequent in vitro culture, quiescent HSCs enter the cell cycle. This enables the analysis of HSCs in 2 different cell cycle stages and the comparison of their responses to different genotoxic noxae. To analyze different mechanisms of DNA damage induction in cells, 2 different genotoxins were compared: etoposide, a topoisomerase II inhibitor that targets mitosis in the S/G2-phase of the cell cycle and the alkylating nitrosamine N-Nitroso-N-methylurea (MNU), which leads to the formation of methyl DNA adducts resulting in DNA double breaks during DNA replication and persistent mutations. Cycling cells recovered after treatment even with higher concentrations of etoposide (1.5µM/ 5µM/10µM), while sorted cells treated with MNU (0.1mM/0.3mM/0.5mM/1mM/3Mm/ 5mM) recovered after treatment with the lower MNU concentrations whereas high MNU concentrations resulted in apoptosis activation. Quiescent cells were not affected by etoposide treatment showing no damage upon entry into the cell cycle. Treatment with MNU, similarly to the cycling cells, resulted in a dose-dependent cell death. In conclusion, we found that depending on the genotoxic trigger and the cycling status, CD34+cells have distinct responses to DNA damage. Cycling cells employ both DDR and apoptosis mechanisms to prevent damage accumulation. Quiescent cells predominantly undergo apoptosis upon damage, but their cell cycle status protects them from certain genotoxic insults.
Topics: Fetal Blood; Etoposide; Hematopoietic Stem Cells; DNA Damage; DNA Repair; Noxae
PubMed: 37962865
DOI: 10.1093/stmcls/sxad085 -
Nucleic Acids Research Dec 2023Sequence context influences structural characteristics and repair of DNA adducts, but there is limited information on how epigenetic modulation affects conformational...
Sequence context influences structural characteristics and repair of DNA adducts, but there is limited information on how epigenetic modulation affects conformational heterogeneity and bypass of DNA lesions. Lesions derived from the environmental pollutant 2-nitrofluorene have been extensively studied as chemical carcinogenesis models; they adopt a sequence-dependent mix of two significant conformers: major groove binding (B) and base-displaced stacked (S). We report a conformation-dependent bypass of the N-(2'-deoxyguanosin-8-yl)-7-fluoro-2-aminofluorene (dG-FAF) lesion in epigenetic sequence contexts (d[5'-CTTCTC#G*NCCTCATTC-3'], where C# is C or 5-methylcytosine (5mC), G* is G or G-FAF, and N is A, T, C or G). FAF-modified sequences with a 3' flanking pyrimidine were better bypassed when the 5' base was 5mC, whereas sequences with a 3' purine exhibited the opposite effect. The conformational basis behind these variations differed; for -CG*C- and -CG*T-, bypass appeared to be inversely correlated with population of the duplex-destabilizing S conformer. On the other hand, the connection between conformation and a decrease in bypass for flanking purines in the 5mC sequences relative to C was more complex. It could be related to the emergence of a disruptive non-S/B conformation. The present work provides novel conformational insight into how 5mC influences the bypass efficiency of bulky DNA damage.
Topics: Base Sequence; Nucleic Acid Conformation; Fluorenes; DNA Adducts; Epigenesis, Genetic; Deoxyguanosine
PubMed: 37953358
DOI: 10.1093/nar/gkad1038 -
Molecular Cell Dec 2023Reactive aldehydes are abundant endogenous metabolites that challenge homeostasis by crosslinking cellular macromolecules. Aldehyde-induced DNA damage requires repair to...
Reactive aldehydes are abundant endogenous metabolites that challenge homeostasis by crosslinking cellular macromolecules. Aldehyde-induced DNA damage requires repair to prevent cancer and premature aging, but it is unknown whether cells also possess mechanisms that resolve aldehyde-induced RNA lesions. Here, we establish photoactivatable ribonucleoside-enhanced crosslinking (PAR-CL) as a model system to study RNA crosslinking damage in the absence of confounding DNA damage in human cells. We find that such RNA damage causes translation stress by stalling elongating ribosomes, which leads to collisions with trailing ribosomes and activation of multiple stress response pathways. Moreover, we discovered a translation-coupled quality control mechanism that resolves covalent RNA-protein crosslinks. Collisions between translating ribosomes and crosslinked mRNA-binding proteins trigger their modification with atypical K6- and K48-linked ubiquitin chains. Ubiquitylation requires the E3 ligase RNF14 and leads to proteasomal degradation of the protein adduct. Our findings identify RNA lesion-induced translational stress as a central component of crosslinking damage.
Topics: Humans; RNA; Ubiquitination; Ubiquitin; Ribosomes; Ubiquitin-Protein Ligases; Aldehydes; Protein Biosynthesis
PubMed: 37951216
DOI: 10.1016/j.molcel.2023.10.012 -
Cells Oct 2023E-cigarette use has been reported to affect cell viability, induce DNA damage, and modulate an inflammatory response resulting in negative health consequences. Most... (Review)
Review
E-cigarette use has been reported to affect cell viability, induce DNA damage, and modulate an inflammatory response resulting in negative health consequences. Most studies focus on oral and lung disease associated with e-cigarette use. However, tissue damage can be found in the cardio-vascular system and even the bladder. While the levels of carcinogenic compounds found in e-cigarette aerosols are lower than those in conventional cigarette smoke, the toxicants generated by the heat of the vaping device may include probable human carcinogens. Furthermore, nicotine, although not a carcinogen, can be metabolized to nitrosamines. Nitrosamines are known carcinogens and have been shown to be present in the saliva of e-cig users, demonstrating the health risk of e-cigarette vaping. E-cig vape can induce DNA adducts, promoting oxidative stress and DNA damage and NF-kB-driven inflammation. Together, these processes increase the transcription of pro-inflammatory cytokines. This creates a microenvironment thought to play a key role in tumorigenesis, although it is too early to know the long-term effects of vaping. This review considers different aspects of e-cigarette-induced cellular changes, including the generation of reactive oxygen species, DNA damage, DNA repair, inflammation, and the possible tumorigenic effects.
Topics: Humans; Electronic Nicotine Delivery Systems; Vaping; Respiratory Aerosols and Droplets; Carcinogens; Epithelial Cells; Nitrosamines; Carcinogenesis; Inflammation; Tumor Microenvironment
PubMed: 37947630
DOI: 10.3390/cells12212552