-
Nature Communications Jun 2024RNA Polymerase (RNAP) II transcription on non-coding repetitive satellite DNAs plays an important role in chromosome segregation, but a little is known about the...
RNA Polymerase (RNAP) II transcription on non-coding repetitive satellite DNAs plays an important role in chromosome segregation, but a little is known about the regulation of satellite transcription. We here show that Topoisomerase I (TopI), not TopII, promotes the transcription of α-satellite DNAs, the main type of satellite DNAs on human centromeres. Mechanistically, TopI localizes to centromeres, binds RNAP II and facilitates RNAP II elongation. Interestingly, in response to DNA double-stranded breaks (DSBs), α-satellite transcription is dramatically stimulated in a DNA damage checkpoint-independent but TopI-dependent manner, and these DSB-induced α-satellite RNAs form into strong speckles in the nucleus. Remarkably, TopI-dependent satellite transcription also exists in mouse 3T3 and Drosophila S2 cells and in Drosophila larval imaginal wing discs and tumor tissues. Altogether, our findings herein reveal an evolutionally conserved mechanism with TopI as a key player for the regulation of satellite transcription at both cellular and animal levels.
Topics: Animals; DNA, Satellite; Humans; Centromere; Mice; DNA Topoisomerases, Type I; Transcription, Genetic; RNA Polymerase II; DNA Breaks, Double-Stranded; Drosophila; Drosophila melanogaster; Evolution, Molecular
PubMed: 38886382
DOI: 10.1038/s41467-024-49567-5 -
Drug Delivery and Translational Research Jun 2024Doxorubicin is a key treatment for breast cancer, but its effectiveness often comes with significant side effects. Its actions include DNA intercalation, topoisomerase... (Review)
Review
Doxorubicin is a key treatment for breast cancer, but its effectiveness often comes with significant side effects. Its actions include DNA intercalation, topoisomerase II inhibition, and reactive oxygen species generation, leading to DNA damage and cell death. However, it can also cause heart problems and low blood cell counts. Current trials aim to improve doxorubicin therapy by adjusting doses, using different administration methods, and combining it with targeted treatments or immunotherapy. Nanoformulations show promise in enhancing doxorubicin's effectiveness by improving drug delivery, reducing side effects, and overcoming drug resistance. This review summarizes recent progress and difficulties in using doxorubicin for breast cancer, highlighting its mechanisms, side effects, ongoing trials, and the potential impact of nanoformulations. Understanding these different aspects is crucial in optimizing doxorubicin's use and improving outcomes for breast cancer patients. This review examines the toxicity of doxorubicin, a drug used in breast cancer treatment, and discusses strategies to mitigate adverse effects, such as cardioprotective agents and liposomal formulations. It also discusses clinical trials evaluating doxorubicin-based regimens, the evolving landscape of combination therapies, and the potential of nanoformulations to optimize delivery and reduce systemic toxicity. The review also discusses the potential of liposomes, nanoparticles, and polymeric micelles to enhance drug accumulation within tumor tissues while sparing healthy organs.
PubMed: 38884850
DOI: 10.1007/s13346-024-01648-0 -
Archiv Der Pharmazie Jun 2024A series of tetrahydrobenzo[b]thiophene derivatives was designed and synthesized as dual topoisomerase (Topo) I/II inhibitors implicating potential DNA intercalation....
Pharmacophore-based, rationale design, and efficient synthesis of novel tetrahydrobenzo[b]thiophene candidates as potential dual Topo I/II inhibitors and DNA intercalators.
A series of tetrahydrobenzo[b]thiophene derivatives was designed and synthesized as dual topoisomerase (Topo) I/II inhibitors implicating potential DNA intercalation. Ethyl-2-amino-3-cyano-4,5,6,7-tetrahydrobenzo[b]thiophene-4-carboxylate (1) was prepared by modification of the Gewald reaction procedure using a FeO nanocatalyst and then it was used as a building block for the synthesis of tetrahydrobenzo[b]thiophene candidates (2-14). Interestingly, compound 14 showed the best cytotoxic potential against hepatocellular, colorectal, and breast cancer cell lines (IC = 7.79, 8.10, and 3.53 µM), respectively, surpassing doxorubicin at breast cancer (IC = 4.17 µM). Meanwhile, the Topo I and II inhibition assay displayed that compound 3 could exhibit the best inhibitory potential among the investigated candidates (IC = 25.26 and 10.01 nM), respectively, in comparison to camptothecin (IC = 28.34 nM) and doxorubicin (IC = 11.01 nM), as reference standards. In addition, the DNA intercalation assay showed that compound 14 could display the best binding affinity with an IC value of 77.82 µM in comparison to doxorubicin (IC = 58.03 µM). Furthermore, cell cycle and apoptosis analyses described that compound 3 prompts the G1 phase arrest in michigan cancer foundation-7 cancer cells and increases the apoptosis ratio by 29.31% with respect to untreated cells (2.25%). Additionally, the conducted molecular docking assured the promising binding of the investigated members toward Topo I and II with potential DNA intercalation. Accordingly, the synthesized compounds could be treated as promising anticancer candidates for future optimization.
PubMed: 38864845
DOI: 10.1002/ardp.202400217 -
Expert Opinion on Therapeutic Patents Jun 2024is a common sexually transmitted disease connected with extensive drug resistance to many antibiotics. Presently, only expanded spectrum cephalosporins (ceftriaxone and... (Review)
Review
INTRODUCTION
is a common sexually transmitted disease connected with extensive drug resistance to many antibiotics. Presently, only expanded spectrum cephalosporins (ceftriaxone and cefixime) and azithromycin remain useful for its management.
AREAS COVERED
New chemotypes for the classical antibiotic drug target gyrase/topoisomerase IV afforded inhibitors with potent binding to these enzymes, with an inhibition mechanism distinct from that of fluoroquinolones, and thus less prone to mutations. The α-carbonic anhydrase from the genome of this bacterium (NgCAα) was also validated as an antibacterial target.
EXPERT OPINION
By exploiting different subunits from the gyrase/topoisomerase IV as well as new chemotypes, two new antibiotics reached Phase II/III clinical trials, zoliflodacin and gepotidacin. They possess a novel inhibition mechanism, binding in distinct parts of the enzyme compared to the fluoroquinolones. Other chemotypes with inhibitory activity in these enzymes were also reported. NgCAα inhibitors belonging to a variety of classes were obtained, with several sulfonamides showing MIC values in the range of 0.25-4 µg/mL and significant activity in animal models of this infection. Acetazolamide and similar CA inhibitors might thus be repurposed as antiinfectives. The scientific/patent literature has been searched for on PubMed, ScienceDirect, Espacenet, and PatentGuru, from 2016 to 2024.
Topics: Neisseria gonorrhoeae; Anti-Bacterial Agents; Humans; Animals; Drug Repositioning; Patents as Topic; Gonorrhea; Drug Resistance, Bacterial; Topoisomerase II Inhibitors; Oxazolidinones; Microbial Sensitivity Tests; DNA Topoisomerase IV; DNA Gyrase; Morpholines; Isoxazoles; Spiro Compounds; Heterocyclic Compounds, 3-Ring; Barbiturates; Acenaphthenes
PubMed: 38856987
DOI: 10.1080/13543776.2024.2367005 -
ELife Jun 2024DNA gyrase, a ubiquitous bacterial enzyme, is a type IIA topoisomerase formed by heterotetramerisation of 2 GyrA subunits and 2 GyrB subunits, to form the active...
DNA gyrase, a ubiquitous bacterial enzyme, is a type IIA topoisomerase formed by heterotetramerisation of 2 GyrA subunits and 2 GyrB subunits, to form the active complex. DNA gyrase can loop DNA around the C-terminal domains (CTDs) of GyrA and pass one DNA duplex through a transient double-strand break (DSB) established in another duplex. This results in the conversion from a positive (+1) to a negative (-1) supercoil, thereby introducing negative supercoiling into the bacterial genome by steps of 2, an activity essential for DNA replication and transcription. The strong protein interface in the GyrA dimer must be broken to allow passage of the transported DNA segment and it is generally assumed that the interface is usually stable and only opens when DNA is transported, to prevent the introduction of deleterious DSBs in the genome. In this paper, we show that DNA gyrase can exchange its DNA-cleaving interfaces between two active heterotetramers. This so-called interface 'swapping' (IS) can occur within a few minutes in solution. We also show that bending of DNA by gyrase is essential for cleavage but not for DNA binding per se and favors IS. Interface swapping is also favored by DNA wrapping and an excess of GyrB. We suggest that proximity, promoted by GyrB oligomerization and binding and wrapping along a length of DNA, between two heterotetramers favors rapid interface swapping. This swapping does not require ATP, occurs in the presence of fluoroquinolones, and raises the possibility of non-homologous recombination solely through gyrase activity. The ability of gyrase to undergo interface swapping explains how gyrase heterodimers, containing a single active-site tyrosine, can carry out double-strand passage reactions and therefore suggests an alternative explanation to the recently proposed 'swivelling' mechanism for DNA gyrase (Gubaev et al., 2016).
Topics: DNA Gyrase; Protein Multimerization; DNA, Bacterial; Escherichia coli; DNA
PubMed: 38856655
DOI: 10.7554/eLife.86722 -
The Journal of Biological Chemistry Jun 2024Meiosis reduces ploidy through two rounds of chromosome segregation preceded by one round of DNA replication. In meiosis I, homologous chromosomes segregate, while in...
Meiosis reduces ploidy through two rounds of chromosome segregation preceded by one round of DNA replication. In meiosis I, homologous chromosomes segregate, while in meiosis II, sister chromatids separate from each other. Topoisomerase II (Topo II) is a conserved enzyme that alters DNA structure by introducing transient double-strand breaks. During mitosis, Topo II relieves topological stress associated with unwinding DNA during replication, recombination, and sister chromatid segregation. Topo II also plays a role in maintaining mitotic chromosome structure. However, the role and regulation of Topo II during meiosis is not well-defined. Previously, we found an allele of Topo II, top-2(it7), disrupts homologous chromosome segregation during meiosis I of Caenorhabditis elegans spermatogenesis. In a genetic screen, we identified different point mutations in 5'-tyrosyl-DNA phosphodiesterase two (Tdp2, C. elegans tdpt-1) that suppress top-2(it7) embryonic lethality. Tdp2 removes trapped Top-2-DNA complexes. The tdpt-1 suppressing mutations rescue embryonic lethality, ameliorate chromosome segregation defects, and restore TOP-2 protein levels of top-2(it7). Here, we show that both TOP-2 and TDPT-1 are expressed in germ line nuclei but occupy different compartments until late meiotic prophase. We also demonstrate that tdpt-1 suppression is due to loss of function of the protein and that the tdpt-1 mutations do not have a phenotype independent of top-2(it7) in meiosis. Lastly, we found that the tdpt-1 suppressing mutations either impair the phosphodiesterase activity, affect the stability of TDPT-1, or disrupt protein interactions. This suggests that the WT TDPT-1 protein is inhibiting chromosome biological functions of an impaired TOP-2 during meiosis.
PubMed: 38844130
DOI: 10.1016/j.jbc.2024.107446 -
Life Science Alliance Aug 2024RNA-binding proteins are frequently deregulated in cancer and emerge as effectors of the DNA damage response (DDR). The non-POU domain-containing octamer-binding protein...
RNA-binding proteins are frequently deregulated in cancer and emerge as effectors of the DNA damage response (DDR). The non-POU domain-containing octamer-binding protein NONO/p54 is a multifunctional RNA-binding protein that not only modulates the production and processing of mRNA, but also promotes the repair of DNA double-strand breaks (DSBs). Here, we investigate the impact of deletion in the murine KP ( , ) cell-based lung cancer model. We show that the deletion of Nono impairs the response to DNA damage induced by the topoisomerase II inhibitor etoposide or the radiomimetic drug bleomycin. Nono-deficient KP (KPN) cells display hyperactivation of DSB signalling and high levels of DSBs. The defects in the DDR are accompanied by reduced RNA polymerase II promoter occupancy, impaired nascent RNA synthesis, and attenuated induction of the DDR factor growth arrest and DNA damage-inducible beta (Gadd45b). Our data characterise Gadd45b as a putative Nono-dependent effector of the DDR and suggest that Nono mediates a genome-protective crosstalk of the DDR with the RNA metabolism via induction of Gadd45b.
Topics: Animals; DNA Repair; Mice; RNA-Binding Proteins; DNA Damage; DNA Breaks, Double-Stranded; Antigens, Differentiation; Bleomycin; DNA-Binding Proteins; Etoposide; Signal Transduction; Lung Neoplasms; Tumor Suppressor Protein p53; Cell Line, Tumor; RNA Polymerase II; Humans; GADD45 Proteins
PubMed: 38843934
DOI: 10.26508/lsa.202302555 -
PloS One 2024Signal regulatory protein alpha (SIRPα) is an immune inhibitory receptor on myeloid cells including macrophages and dendritic cells, which binds to CD47, a ubiquitous...
Signal regulatory protein alpha (SIRPα) is an immune inhibitory receptor on myeloid cells including macrophages and dendritic cells, which binds to CD47, a ubiquitous self-associated molecule. SIRPα-CD47 interaction is exploited by cancer cells to suppress anti-tumor activity of myeloid cells, therefore emerging as a novel immune checkpoint for cancer immunotherapy. In blood cancer, several SIRPα-CD47 blockers have shown encouraging monotherapy activity. However, the anti-tumor activity of SIRPα-CD47 blockers in solid tumors seems limited, suggesting the need for combination therapies to fully exploit the myeloid immune checkpoint in solid tumors. Here we tested whether combination of SIRPα-CD47 blocker with antibody-drug conjugate bearing a topoisomerase I inhibitor DXd (DXd-ADC) would enhance anti-tumor activity in solid tumors. To this end, DS-1103a, a newly developed anti-human SIRPα antibody (Ab), was assessed for the potential combination benefit with datopotamab deruxtecan (Dato-DXd) and trastuzumab deruxtecan (T-DXd), DXd-ADCs targeting human trophoblast cell-surface antigen 2 and human epidermal growth factor receptor 2, respectively. DS-1103a inhibited SIRPα-CD47 interaction and enhanced antibody-dependent cellular phagocytosis of Dato-DXd and T-DXd against human cancer cells. In a whole cancer cell vaccination model, vaccination with DXd-treated cancer cells led to activation of tumor-specific T cells when combined with an anti-mouse SIRPα (anti-mSIRPα) Ab, implying the benefit of combining DXd-ADCs with anti-SIRPα Ab on anti-tumor immunity. Furthermore, in syngeneic mouse models, both Dato-DXd and T-DXd combination with anti-mSIRPα Ab showed stronger anti-tumor activity over the monotherapies. Taken together, this study provides a preclinical rationale of novel therapies for solid tumors combining SIRPα-CD47 blockers with DXd-ADCs.
Topics: CD47 Antigen; Animals; Receptors, Immunologic; Humans; Mice; Immunoconjugates; Antigens, Differentiation; Cell Line, Tumor; Female; Trastuzumab; Topoisomerase I Inhibitors; Immunotherapy; Mice, Inbred BALB C
PubMed: 38843278
DOI: 10.1371/journal.pone.0304985 -
Nature Communications May 2024Type II topoisomerases are ubiquitous enzymes that play a pivotal role in modulating the topological configuration of double-stranded DNA. These topoisomerases are...
Type II topoisomerases are ubiquitous enzymes that play a pivotal role in modulating the topological configuration of double-stranded DNA. These topoisomerases are required for DNA metabolism and have been extensively studied in both prokaryotic and eukaryotic organisms. However, our understanding of virus-encoded type II topoisomerases remains limited. One intriguing example is the African swine fever virus, which stands as the sole mammalian-infecting virus encoding a type II topoisomerase. In this work, we use several approaches including cryo-EM, X-ray crystallography, and biochemical assays to investigate the structure and function of the African swine fever virus type II topoisomerase, pP1192R. We determine the structures of pP1192R in different conformational states and confirm its enzymatic activity in vitro. Collectively, our results illustrate the basic mechanisms of viral type II topoisomerases, increasing our understanding of these enzymes and presenting a potential avenue for intervention strategies to mitigate the impact of the African swine fever virus.
Topics: African Swine Fever Virus; DNA Topoisomerases, Type II; Animals; Crystallography, X-Ray; Cryoelectron Microscopy; Swine; Viral Proteins; Models, Molecular; Protein Conformation; African Swine Fever
PubMed: 38816407
DOI: 10.1038/s41467-024-49047-w -
Scientific Reports May 2024DNA topoisomerase II alpha (TOP2A) expression, gene alterations, and enzyme activity have been studied in various malignant tumors. Abnormal elevation of TOP2A...
DNA topoisomerase II alpha (TOP2A) expression, gene alterations, and enzyme activity have been studied in various malignant tumors. Abnormal elevation of TOP2A expression is considered to be related to the development of non-small cell lung cancer (NSCLC). However, its association with tumor metastasis and its mode of action remains unclear. Bioinformatics, real-time quantitative PCR, immunohistochemistry and immunoblotting were used to detect TOP2A expression in NSCLC tissues and cells. Cell migration and invasion assays as well as cytoskeletal staining were performed to analyze the effects of TOP2A on the motility, migration and invasion ability of NSCLC cells. Cell cycle and apoptosis assays were used to verify the effects of TOP2A on apoptosis as well as cycle distribution in NSCLC. TOP2A expression was considerably upregulated in NSCLC and significantly correlated with tumor metastasis and the occurrence of epithelial-mesenchymal transition (EMT) in NSCLC. Additionally, by interacting with the classical ligand Wnt3a, TOP2A may trigger the canonical Wnt signaling pathway in NSCLC. These observations suggest that TOP2A promotes EMT in NSCLC by activating the Wnt/β-catenin signaling pathway and positively regulates malignant events in NSCLC, in addition to its significant association with tumor metastasis. TOP2A promotes the metastasis of NSCLC by stimulating the canonical Wnt signaling pathway and inducing EMT. This study further elucidates the mechanism of action of TOP2A, suggesting that it might be a potential therapeutic target for anti-metastatic therapy.
Topics: DNA Topoisomerases, Type II; Humans; Carcinoma, Non-Small-Cell Lung; Lung Neoplasms; Epithelial-Mesenchymal Transition; Poly-ADP-Ribose Binding Proteins; Cell Movement; Cell Line, Tumor; Gene Expression Regulation, Neoplastic; Neoplasm Metastasis; Wnt Signaling Pathway; Apoptosis; Male; Female; Middle Aged; Wnt3A Protein
PubMed: 38806610
DOI: 10.1038/s41598-024-63055-2