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By applying our pioneering "Targeted Drug Conjugate (TDC)" concept, a new PARP1-specific Pt(II)-based TDC for the treatment of ovarian cancer was reported. In vitro biological assays indicated that the representative compound Ola-604 could target PARP1, exhibit an inhibitory effect on SKOV3 cancer cells, and overcome cisplatin resistance via inducing cell apoptosis, causing cell cycle arrest, enhancing the cellular accumulation of platinum element, promoting the level of DNA platination within the genome, and suppressing DNA damage repair. Notably, compound Ola-604 demonstrated higher tumor growth inhibitory efficacy than cisplatin, olaparib, and their physical mixture in SKOV3 mice xenograft models, while exhibiting lower toxicity. Overall, the TDC entity sets a new benchmark for precision therapy in ovarian cancer. Show less

Abstract Most clinically used chemotherapeutic agents act by inducing apoptosis. However, their clinical effectiveness is often limited by poor therapeutic efficacy and the rapid development of drug resistance. In contrast, oncosis, as an inflammatory form of cell death independent of adenosine triphosphate (ATP) and apoptotic pathways, exhibits unique advantages in overcoming tumor drug resistance and regulating anti‐tumor immune responses. Herein, we present the first iridium(III)‐based immunogenic oncosis inducers designed to concurrently induce oncosis and activate the cGAS–STING pathway, thereby bridging chemotherapy with immunotherapy. Through a bioisosteric design strategy, we identified benzoselenazole and benzothiazole derivatives as key pharmacophores for triggering oncosis. These iridium(III)‐based oncosis‐inducers rapidly disrupt mitochondrial architecture, induce oxidative stress, and promote Ca(II) release, which subsequently activate calpain and porimin to initiate oncosis in multidrug‐resistant cancer cells. Transcriptomic profiling further revealed their ability to regulate actin cytoskeleton organization, modulate ABC transporter activity, and affect glycolysis/gluconeogenesis. Notably, the metal complexes induce mitochondrial swelling and mt‐DNA damage, leading to robust activation of the cGAS–STING innate immune pathway and eliciting a strong anticancer immune response. Based on these multimodal mechanisms, the Ir(III)‐based immunogenic oncosis inducers were able to effectively kill drug‐resistant cancer cells and enhance the anticancer immune response in tumor mouse models. Show less

Z-DNA-binding protein 1 (ZBP1; also known as DAI or DLM-1) regulates cell death and inflammation by sensing left-handed double-helical nucleic acids, including Z-RNA and Z-DNA. However, the physiological conditions that generate Z-form nucleic acids (Z-NAs) and activate ZBP1-dependent signaling pathways remain largely elusive. In this study, we developed a probe, Zα-mFc, that specifically detected both Z-DNA and Z-RNA. Utilizing this probe, we discovered that inhibiting spliceosome causes nuclear accumulation of Z-RNA:DNA hybrids, which are sensed by ZBP1 via its Zα domains, triggering apoptosis and necroptosis in mammalian cells. Furthermore, we solved crystal structures of the human or mouse Zα1 domain complexed with a 6-bp RNA:DNA hybrid, revealing that the RNA:DNA hybrid adopts a left-handed conformation. Our findings demonstrate that the spliceosome acts as a checkpoint preventing accumulation of Z-RNA:DNA hybrids, which potentially function as endogenous ligands activating ZBP1-dependent cell death pathways. Show less

ABSTRACTThe nucleolus, a prominent membrane‐less nuclear compartment, is organized around ribosomal RNA (rRNA) gene (rDNA) clusters, known as nucleolar organizing regions (NORs), located on the short arms of acrocentric chromosomes. It serves as the primary site for ribosome biogenesis, an energy‐intensive process crucial for cell growth and proliferation. This involves RNA polymerase I (Pol I)‐mediated transcription of 47S precursor rRNA (pre‐rRNA), pre‐rRNA processing, and ribosomal subunit assembly, reflected in its tripartite structure maintained by liquid–liquid phase separation. Recent evidence indicates that only about 30% of nucleolar proteins are exclusively involved in ribosome production. The remaining proteome participates in diverse cellular functions, establishing the nucleolus as a multifunctional organelle. It functions as a critical stress sensor and signaling hub, responding to various intracellular insults such as nutrient starvation, DNA damage, and viral infection. Many chemotherapeutic agents also induce the response called nucleolar stress via disruption of the nucleolar structure or function, potentially leading to rDNA instability. Nucleolar stress frequently leads to dynamic transition of nucleolar proteins, inducing nucleolar reorganization. Of these, the stress induced by transcriptional changes leads to the unique nucleolar structures termed nucleolar caps and nucleolar necklaces. In this review, we summarize the recent findings about the molecular mechanism of nucleolar changes upon stresses and discuss the possible relationship between rDNA instability and cancer. Show less

Platinum-based drugs are a mainstay in chemotherapy, with traditional forms exerting their work directly on DNA. In recent years, it has been observed that platinum complexes had the potential to induce immunogenic cell death (ICD) and effectively trigger antitumor immune responses. Herein, to obtain novel platinum complexes with chemo-immunological properties, a series of Pt(ΙΙ)-N-heterocyclic carbene (Pt(ΙΙ)-NHC) complexes derived from 4,5-diarylimidazoles were synthesized. Among them, the dominant complex 3f was proved to exhibit better anti-liver cancer capacity compared to cisplatin and oxaliplatin. Complex 3f showed the ability to cause DNA damage by binding to DNA. In addition, it triggered intracellular reactive oxygen species (ROS) generation, affected the function of mitochondria, and blocked cells in G0/G1 phase, ultimately induced apoptosis in liver cancer cells. Furthermore, complex 3f activated endoplasmic reticulum stress (ERS) which promoted the release of damage-associated molecular patterns (DAMPs), induced ICD and dendritic cells (DCs) maturation. Interestingly, complex 3f also upregulated PD-L1, consequently converted "cold tumors" into "hot tumors". Overall, complex 3f had the potential to be regarded as a promising chemoimmunotherapy for the treatment of liver cancer. Show less

AbstractOne of the conventional ways to eradicate tumor cells is to utilize chemotherapy agents, e.g., cisplatin, to induce DNA damage. However, DNA damage repair mechanisms can significantly limit the therapeutic efficacy of cisplatin. These mechanisms enable tumor cells to repair the DNA damage caused by the drug, leading to resistance. Cisplatin and similar drugs bind to specific DNA sites without significantly altering their conformation. As a result, DNA repair enzymes can still attach to and repair the damaged DNA. To address this issue, we designed four Ru(II) complexes (RuC3, RuC6, RuC9, and RuC12) with high positive charges of +8 valence and regulated their nuclear accumulation levels by adjusting the length of alkyl chains. RuC9 exhibits the highest nucleus accumulation level. DNA conformation was significantly altered by inducing DNA condensation through indiscriminately neutralizing the negative charge of the DNA backbone. This significant change prevents DNA‐related enzymes from binding to DNA, ultimately leading to the efficient eradication of various tumor cell lines. To the best of our knowledge, it is the first work that kills tumor cells and overcomes cisplatin resistance through inducing DNA condensation. Show less

Cisplatin and its analogs are extensively utilized as metal-based anticancer agents in clinical settings due to their mechanism of action, which involves targeting genomic double-stranded DNA to induce cytotoxicity in cancer cells. However, the associated severe side effects and DNA damage repair-inducing drug resistance present significant challenges. In recent years, G-quadruplex nucleic acids, formed through the self-assembly of guanine-rich nucleic acid sequences, have emerged as a compelling target for the design of novel anticancer therapeutics. The strategic design of platinum complexes that selectively interact with, stabilize, or cleave G-quadruplex structures represents a promising approach for developing effective anticancer agents to overcome cisplatin resistance. This review will emphasize the advancements made over the past decade in interacting G-quadruplexes with platinum complexes as potential anticancer therapeutics. The ongoing development of platinum complexes spans from targeting nuclear DNA G-quadruplexes to mitochondrial DNA and cytoplasmic RNA G-quadruplexes, evolving from monotherapy approaches, such as chemotherapy and photodynamic therapy, to a combination of radiotherapy, immunotherapy, and more, highlighting the dynamic progress of platinum complexes. At the end, we have summarized 4 points of pending issues in this fast-growing field, which we hope can provide some help to the development of this field. Show less

Copper is a trace element which is essential for biological organisms, and its homeostatic balance is important for living organisms to maintain the normal function. When the copper homeostasis is disordered, the cellular function and structure will be disrupted. Excess copper cause oxidative stress and DNA damage in cells, thereby inducing regulated cell death such as apoptosis and necroptosis. Excess copper in mitochondria can bind to lipoylated proteins in the tricarboxylic acid (TCA) cycle and cause them to aggregate, resulting in proteotoxic stress and eliciting a novel cell death modality: cuproptosis. Cancer cells have a greater demand for copper compared to normal tissue, and high levels of copper ions are closely associated with tumour proliferation and metastasis. The anti-tumor mechanisms of copper include the production of oxidative stress, inhibition of the ubiquitin–proteasome system, suppression of angiogenesis, and induction of copper-dependent cell death. Targeting copper is one of the current directions in oncology research, including the use of copper ion carriers to increase intracellular copper levels to induce oxidative stress and cuproptosis, as well as the use of copper ion chelators to reduce copper bioavailability. However, copper complexes have certain toxicity, so their biosafety needs to be improved. Emerging nanotechnology is expected to solve this problem by utilizing copper-based nanomaterials (Cu-based NMs) to deliver copper ions and a variety of drugs with different functions, thereby improving the anti-tumor efficacy and reducing the side effects. Therefore, a thorough understanding of copper metabolic processes and the mechanism of cuproptosis will greatly benefit anti-tumor therapy. This review summarizes the processes of copper metabolism and the mechanism of cuproptosis. In addition, we discuss the current anti-tumor paradigms related to copper, we also discuss current nanotherapeutic approaches to copper mortality and provide prospective insights into the future copper-mediated cancer therapy. Show less

Background

Cyclin-dependent kinase 9 (CDK9) is a crucial regulator of transcriptional progression of RNA polymerase-II (RNAP2). RNA polymerases trapped in DNA can be a source of transcription-replication conflict (T-R conflict), which is a common source of replication stress. AZD4573, a highly selective CDK9 inhibitor, has been shown to induce apoptosis in leukemia cell lines, while its anti-tumor potential in breast cancer has yet to be elucidated.

Methods

To evaluate the cytotoxicity of AZD4573 in vitro, MTT assays were performed. The expression of signal transduction molecules was determined using Western blotting, immunoprecipitation, and immunofluorescence. Apoptotic cell death was verified by the annexin-V assay. DNA strand breaks and repair efficacy were evaluated through the alkaline comet assay. The siRNA knock-down system was used to confirm the action mechanism.

Results

AZD4573 induced T-R conflicts during S-phase, increasing replication stress and DNA strand breaks, resulting in apoptosis by induction of caspase-3. Furthermore, we identified Dead-box 25 (DDX25) helicase as a key mediator in resolving the T-R conflicts. Nuclear translocation of DDX25 correlated with reduced sensitivity to AZD4573 by the resolution of T-R conflicts.

Conclusions

Inhibition of CDK9 by AZD4573 induces the accumulation of DNA damage through T-R conflicts. DDX25 helicases were identified as a key mediator in resolving T-R conflicts and the reduced sensitivity to AZD4573. Show less

As two pivotal regulatory factors in cancer biology, oxidative stress and inflammation interact dynamically through complex network mechanisms to influence tumor initiation, progression, and treatment resistance. Oxidative stress induces genomic instability, oncogenic signaling activation, and tumor microenvironment (TME) remodeling via the abnormal accumulation of reactive oxygen species (ROS) or reactive nitrogen species (RNS). Conversely, inflammation sustains malignant phenotypes by releasing pro-inflammatory cytokines and chemokines and promoting immune cell infiltration. These processes create a vicious cycle via positive feedback loops whereby oxidative stress initiates inflammatory signaling, while the inflammatory milieu further amplifies ROS/RNS production, collectively promoting proliferation, migration, angiogenesis, drug resistance, and immune evasion in tumor cells. Moreover, their crosstalk modulates DNA damage repair, metabolic reprogramming, and drug efflux pump activity, significantly impacting the sensitivity of cancer cells to chemotherapy, radiotherapy, and targeted therapies. This review systematically discusses these advances and the molecular mechanisms underlying the interplay between oxidative stress and inflammation in cancer biology. It also explores their potential as diagnostic biomarkers and prognostic indicators and highlights novel therapeutic strategies targeting the oxidative stress-inflammation axis. The goal is to provide a theoretical framework and translational roadmap for developing synergistic anti-tumor therapies. Show less

A branch of the nucleotide excision repair (NER) pathway, transcription-coupled repair (TCR or TC-NER) specifically operates on the template DNA strand of actively transcribed genes. Initiated by stalling of elongating RNA polymerase complexes at damaged sites, TC-NER has historically been viewed as "accelerated repair", arguably necessary for the maintenance of vital transcription function. Conversely, the conventional "global genome" (GG-NER) mechanism, operating throughout the genome, is usually regarded as a much slower process, even though it has long been found that differences in repair kinetics between transcribed DNA and the rest of the genome are not manifested for all structural types of DNA damage. Considering that damage detection is the rate-limiting step of overall repair reactions in most cases and that the mechanisms of the initial recognition of modified DNA structure are fundamentally different between TC-NER and GG-NER, it is suggestive to attribute the observed kinetic differences to different damage spectra recognized by the two pathways. This review summarizes current knowledge on the differential requirements of TC-NER and GG-NER towards specific damage types, based on their structural rather than spatial characteristics, and highlights some common features of DNA modifications repaired preferentially or exclusively by TC-NER, while evading other repair mechanisms. Show less

The tumor suppressor protein, p53, which is mutated in half of human tumors, plays a critical role in cellular responses to DNA damage and maintenance of genome stability. Therefore, increasing our understanding of the p53 pathway is essential for improving cancer treatment and diagnosis. Show less

The effectiveness of existing systemic and targeted therapies remains limited in triple-negative breast cancer (TNBC) treatment. Much research has been conducted on reactive oxygen species (ROS)-mediated cancer cell death to overcome the shortcomings of the currently applied chemotherapeutic treatments. Herein, we have developed novel Ru(II)/Ir(III)-mediated triazolylpyridine complexes as ROS inducers. Upon entering the TNBC cells, the Ru(II) complex effectively accumulated in mitochondria and triggered the creation of ROS, facilitating dysfunction of mitochondria and oxidative DNA damage, ultimately causing death of cells through G2/M phase cell cycle arrest. Eventually, this complex induced the upregulation of BAX (pro-apoptotic protein) and downregulation of BCL-2 (antiapoptotic protein) and triggered the caspase 3/9 pathway and released cytochrome c in the cytosol for apoptosis. The complex JRu (RuII triazolylpyridine) significantly reduced the integrity and viability of TNBC 3D spheroids. Show less

The nucleotide excision repair (NER) mechanism is responsible for removing bulky DNA damage, such as pyrimidine dimers induced by ultraviolet (UV) light. The NER pathway excises the damaged strand through incisions at the 5’ and 3’ ends of the damage, with the 5’ incision catalyzed by the XPF-ERCC1 endonuclease complex. Here, we identify an XPF ortholog in Trypanosoma brucei, the causative agent of human African trypanosomiasis (sleeping sickness). XPF-deficient parasites exhibit hypersensitivity to UV irradiation and a slower rate of DNA damage repair. Consistent with its role in DNA repair, XPF localizes to the nucleus, associating with nucleoplasmic and nucleolar regions. Additionally, we demonstrate that TbXPF protects against intra- and inter-strand crosslinks induced by cisplatin and mitomycin C, respectively. The presence of a functional NER pathway in trypanosomes suggests that these organisms are susceptible to replication- and transcription-blocking DNA damage in vivo. Under genotoxic stress, genome stability and parasite survival may heavily rely on DNA repair systems such as NER which, for this reason, could be an effective target for chemotherapeutic interventions. Show less

Copper(II), manganese(II), and mercury(II) complexes of 4-amino-5-(2-(1-pyridine-2-yl)ethylidene)hydrazinyl)-4H-1,2,4-triazole-3-thiol (H2TAP) were synthesized and characterized using CHN analysis, FT-IR, 1H-NMR, 13C-NMR, UV–Vis, ESR, MS, PXRD, magnetic moment measurements, molar conductance, and TG/DTA. DFT calculations indicate octahedral geometries and the neutral bidentate or tridentate chelating behavior of the ligand. Cyclic voltammetry revealed the complexes’ redox properties, and Job’s method elucidated stoichiometric compositions in solution. Biochemical assays demonstrated antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Candida albicans. The MnII complex exhibited potent antitumor activity against HepG-2 cells. Antioxidant and DNA binding studies showed promising results, with docking investigations indicating strong interactions between the ligand/complexes and target proteins (PDB: 1YWN) and DNA (PDB: 8EC1), suggesting therapeutic potential. Show less

Protein Arginine Methyltransferases (PRMTs) are a family of enzymes regulating protein arginine methylation, which is a post-translational modification crucial for various cellular processes. Recent studies have highlighted the mechanistic role of PRMTs in cancer pathogenesis, immunotherapy, and drug resistance. PRMTs are involved in diverse oncogenic processes, including cell proliferation, apoptosis, and metastasis. They exert their effects by methylation of histones, transcription factors, and other regulatory proteins, resulting in altered gene expression patterns. PRMT-mediated histone methylation can lead to aberrant chromatin remodeling and epigenetic changes that drive oncogenesis. Additionally, PRMTs can directly interact with key signaling pathways involved in cancer progression, such as the PI3K/Akt and MAPK pathways, thereby modulating cell survival and proliferation. In the context of cancer immunotherapy, PRMTs have emerged as critical regulators of immune responses. They modulate immune checkpoint molecules, including programmed cell death protein 1 (PD-1), through arginine methylation. Drug resistance is a significant challenge in cancer treatment, and PRMTs have been implicated in this phenomenon. PRMTs can contribute to drug resistance through multiple mechanisms, including the epigenetic regulation of drug efflux pumps, altered DNA damage repair, and modulation of cell survival pathways. In conclusion, PRMTs play critical roles in cancer pathogenesis, immunotherapy, and drug resistance. In this overview, we have endeavored to illuminate the mechanistic intricacies of PRMT-mediated processes. Shedding light on these aspects will offer valuable insights into the fundamental biology of cancer and establish PRMTs as promising therapeutic targets. Show less

Drug resistance remains a major challenge in cancer treatment, necessitating the development of novel strategies to overcome it. Protein arginine methyltransferases (PRMTs) are enzymes responsible for epigenetic arginine methylation, which regulates various biological and pathological processes, as a result, they are attractive therapeutic targets for overcoming anti-cancer drug resistance. The ongoing development of small molecules targeting PRMTs has resulted in the generation of chemical probes for modulating most PRMTs and facilitated clinical treatment for the most advanced oncology targets, including PRMT1 and PRMT5. In this review, we summarize various mechanisms underlying protein arginine methylation and the roles of specific PRMTs in driving cancer drug resistance. Furthermore, we highlight the potential clinical implications of PRMT inhibitors in decreasing cancer drug resistance. PRMTs promote the formation and maintenance of drug-tolerant cells via several mechanisms, including altered drug efflux transporters, autophagy, DNA damage repair, cancer stem cell-related function, epithelial-mesenchymal transition, and disordered tumor microenvironment. Multiple preclinical and ongoing clinical trials have demonstrated that PRMT inhibitors, particularly PRMT5 inhibitors, can sensitize cancer cells to various anti-cancer drugs, including chemotherapeutic, targeted therapeutic, and immunotherapeutic agents. Combining PRMT inhibitors with existing anti-cancer strategies will be a promising approach for overcoming anti-cancer drug resistance. Furthermore, enhanced knowledge of the complex functions of arginine methylation and PRMTs in drug resistance will guide the future development of PRMT inhibitors and may help identify new clinical indications. Show less

Nucleotide excision repair (NER) is vital for genome integrity. Yet, our understanding of the complex NER protein machinery remains incomplete. Combining cryo-EM and XL-MS data with AlphaFold2 predictions, we build an integrative model of the NER pre-incision complex(PInC). Here TFIIH serves as a molecular ruler, defining the DNA bubble size and precisely positioning the XPG and XPF nucleases for incision. Using simulations and graph theoretical analyses, we unveil PInC's assembly, global motions, and partitioning into dynamic communities. Remarkably, XPG caps XPD's DNA-binding groove and bridges both junctions of the DNA bubble, suggesting a novel coordination mechanism of PInC's dual incision. XPA rigging interlaces XPF/ERCC1 with RPA, XPD, XPB, and 5' ssDNA, exposing XPA's crucial role in licensing the XPF/ERCC1 incision. Mapping disease mutations onto our models reveals clustering into distinct mechanistic classes, elucidating xeroderma pigmentosum and Cockayne syndrome disease etiology. Show less

It is well established that oxaliplatin, one of the three Pt(II) anticancer drugs approved worldwide, and phenanthriplatin, an important preclinical monofunctional Pt(II) anticancer drug, possess a different mode of action from that of cisplatin and carboplatin, namely, the induction of nucleolar stress. The exact mechanisms that lead to Pt-induced nucleolar stress are, however, still poorly understood. As such, studies aimed at better understanding the biological targets of both oxaliplatin and phenanthriplatin are urgently needed to expand our understanding of Pt-induced nucleolar stress and guide the future design of Pt chemotherapeutics. One approach that has seen great success in the past is the use of Pt-click complexes to study the biological targets of Pt drugs. Herein, we report the synthesis and characterization of the first examples of click-capable phenanthriplatin complexes. Furthermore, through monitoring the relocalization of nucleolar proteins, RNA transcription levels, and DNA damage repair biomarker γH2AX, and by investigating their in vitro cytotoxicity, we show that these complexes successfully mimic the cellular responses observed for phenanthriplatin treatment in the same experiments. The click-capable phenanthriplatin derivatives described here expand the existing library of Pt-click complexes. Significantly they are suitable for studying nucleolar stress mechanisms and further elucidating the biological targets of Pt complexes. Show less

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease characterised by antibodies to DNA (anti-DNA) and other nuclear macromolecules. Anti-DNA antibodies are markers for classification and disease activity and promote pathogenesis by forming immune complexes that deposit in the tissue or stimulate cytokine production. Studies on the antibody response to DNA have focused primarily on a conformation of DNA known as B-DNA, the classic right-handed double helix. Among other conformations of DNA, Z-DNA is a left-handed helix with a zig-zag backbone; hence, the term Z-DNA. Z-DNA formation is favoured by certain base sequences, with the energetically unfavourable flip from B-DNA to Z-DNA dependent on conditions. Z-DNA differs from B-DNA in its immunogenicity in animal models. Furthermore, anti-Z-DNA antibodies, but not anti-B-DNA antibodies, can be present in otherwise healthy individuals. In SLE, antibodies to Z-DNA can occur in association with antibodies to B-DNA as a cross-reactive response, rising and falling together. While formed transiently in chromosomal DNA, Z-DNA is stably present in bacterial biofilms; biofilms can provide protection against antibiotics and other challenges including elements of host defence. The high GC content of certain bacterial DNA also favours Z-DNA formation as do DNA-binding proteins of bacterial or host origin. Together, these findings suggest that sources of Z-DNA can enhance the immunogenicity of DNA and, in SLE, stimulate the production of cross-reactive antibodies that bind both B-DNA and Z-DNA. As such, DNA can act as a molecular chameleon that, when stabilised in the Z-DNA conformation, can drive autoimmunity. Show less

DNA damage occurs throughout life from a variety of sources, and it is imperative to repair damage in a timely manner to maintain genome stability. Thus, DNA repair mechanisms are a fundamental part of life. Nucleotide excision repair (NER) plays an important role in the removal of bulky DNA adducts, such as cyclobutane pyrimidine dimers from ultraviolet light or DNA crosslinking damage from platinum-based chemotherapeutics, such as cisplatin. A main component for the NER pathway is transcription factor IIH (TFIIH), a multifunctional, 10-subunit protein complex with crucial roles in both transcription and NER. In transcription, TFIIH is a component of the pre-initiation complex and is important for promoter opening and the phosphorylation of RNA Polymerase II (RNA Pol II). During repair, TFIIH is important for DNA unwinding, recruitment of downstream repair factors, and verification of the bulky lesion. Several different disease states can arise from mutations within subunits of the TFIIH complex. Most strikingly are xeroderma pigmentosum (XP), XP combined with Cockayne syndrome (CS), and trichothiodystrophy (TTD). Here, we summarize the recruitment and functions of TFIIH in the two NER subpathways, global genomic (GG-NER) and transcription-coupled NER (TC-NER). We will also discuss how TFIIH's roles in the two subpathways lead to different genetic disorders. Show less

Necrotizing enterocolitis (NEC) involves intestinal epithelial damage and inflammatory response and is associated with high morbidity and mortality in infants. To improve therapeutic prospects, elucidating underlying molecular mechanisms of intestinal epithelial damage during NEC is of the essence. Poly (ADP-ribose) polymerase 1 (PARP1)-dependent parthanatos is a programmed inflammatory cell death. In the present study, the presence of parthanatos-associated proteins PARP1 and poly (ADP-ribose) (PAR), along with high expression of DNA damage-associated biomarkers, 8-hydroxy-2’-deoxyguanosine (8-OHdG) and phosphorylation of histone H2AX (γH2AX), were discovered in the intestinal tissues of NEC infants. Additionally, the upregulated expression of PARP1 and PAR in NEC intestinal tissues correlated distinctly with clinical indices indicative of NEC incidence and severity. Furthermore, we demonstrated that inhibiting the expression of parthanatos-associated proteins, by either pharmacological blockage using 3-aminobenzamide (3-AB), an inhibitor of PARP1, or genetic knockout using Parp1-deficient mice, resulted in substantial improvements in both histopathological severity scores associated with intestinal injury and inflammatory reactions. Moreover, in an in vitro NEC model, reactive oxygen species (ROS)-induced DNA damage promoted the formation of PAR and nuclear translocation of apoptosis-inducing factor (AIF), thus activating PARP1-dependent parthanatos in Caco-2 cells and human intestinal organoids. Our work verifies a previously unexplored role for parthanatos in intestinal epithelial damage during NEC and suggests that inhibition of parthanatos may serve as a potential therapeutic strategy for intervention of NEC. Show less

Hereditary nucleotide excision repair deficiencies cause different cancerous and progeroid disorders of which the exact etiology is not understood. This study finds that prolonged binding of DNA repair factor TFIIH to DNA damage contributes to a more severe phenotype caused by DNA repair deficiency. Show less

Abstract The mechanisms of action for the platinum compounds cisplatin and oxaliplatin have yet to be fully elucidated, despite the worldwide use of these drugs. Recent studies suggest that the two compounds may be working through different mechanisms, with cisplatin inducing cell death via the DNA damage response (DDR) and oxaliplatin utilizing a nucleolar stress-based cell death pathway. While cisplatin- induced DDR has been subject to much research, the mechanisms for oxaliplatin’s influence on the nucleolus are not well understood. Prior work has outlined structural parameters for Pt(II) derivatives capable of nucleolar stress induction. In this work, we gain insight into the nucleolar stress response induced by these Pt(II) derivatives by investigating potential correlations between this unique pathway and DDR. Key findings from this study indicate that Pt(II)-induced nucleolar stress occurs when DDR is inhibited and works independently of the ATM/ATR-dependent DDR pathway. We also determine that Pt(II)-induced stress may be linked to the G1 cell cycle phase, as cisplatin can induce nucleolar stress when cell cycle inhibition occurs at the G1/S checkpoint. Finally, we compare Pt(II)-induced nucleolar stress with other small-molecule nucleolar stress-inducing compounds Actinomycin D, BMH-21, and CX-5461, and find that only Pt(II) compounds cause irreversible nucleolar stress. Taken together, these findings contribute to a better understanding of Pt(II)-induced nucleolar stress, its deviation from ATM/ATR- dependent DDR, and the possible influence of cell cycle on the ability of Pt(II) compounds to cause nucleolar stress. Show less

AbstractArtificial metallo‐nucleases (AMNs) are small molecule DNA cleavage agents, also known as DNA molecular scissors, and represent an important class of chemotherapeutic with high clinical potential. This review provides a primary level of exploration on the concepts key to this area including an introduction to DNA structure, function, recognition, along with damage and repair mechanisms. Building on this foundation, we describe hybrid molecules where AMNs are covalently attached to directing groups that provide molecular scissors with enhanced or sequence specific DNA damaging capabilities. As this research field continues to evolve, understanding the applications of AMNs along with synthetic conjugation strategies can provide the basis for future innovations, particularly for designing new artificial gene editing systems. Show less

DNA crosslinking agents such as cisplatin and related platinum(II) analogs are effective drugs to treat solid tumors. However, these therapeutics can cause high toxicity in the body, and tumors can develop resistance to them. To develop less toxic and more effective DNA crosslinkers, medicinal chemists have focused on tuning the ligands in square planar platinum(II) complexes to modulate their bioavailability, targeted cell penetration, and DNA binding rates. Unfortunately, linking in vitro DNA binding capacity of DNA crosslinkers with their in vivo efficacy has proven challenging. Here we report an electrochemical biosensor strategy that allows the study of platinum(II)-DNA binding in real time. Our biosensors contain a purine-rich deoxynucleotide sequence, T6 (AG)10 , modified with a 5' hexylthiol linker for easy self-assembly onto gold electrodes. The 3' terminus is functionalized with the redox reporter methylene blue. Electron transfer from methylene blue to the sensor is a function of platinum(II) compound concentration and reaction time. Using these biosensors, we resolve DNA binding mechanisms including monovalent and bivalent binding, as well as base stacking. Our approach can measure DNA binding kinetics in buffers and in 50 % serum, offering a single-step, real-time approach to screen therapeutic compounds during drug development. Show less

Significance: Reactive oxygen species (ROS) are generated during mitochondrial oxidative metabolism, and are tightly controlled through homeostatic mechanisms to maintain intracellular redox, regulating growth and proliferation in healthy cells. However, ROS production is perturbed in cancers where abnormal accumulation of ROS leads to oxidative stress and genomic instability, triggering oncogenic signaling pathways on one hand, while increasing oxidative damage and triggering ROS-dependent death signaling on the other. Recent Advances: Our review illuminates how critical interactions between ROS and oncogenic signaling, the tumor microenvironment, and DNA damage response (DDR) pathways have led to interest in ROS modulation as a means of enhancing existing anticancer strategies and developing new therapeutic opportunities. Critical Issues: ROS equilibrium exists via a delicate balance of pro-oxidant and antioxidant species within cells. "Antioxidant" approaches have been explored mainly in the form of chemoprevention, but there is insufficient evidence to advocate its routine application. More progress has been made via the "pro-oxidant" approach of targeting cancer vulnerabilities and inducing oxidative stress. Various therapeutic modalities have employed this approach, including direct ROS-inducing agents, chemotherapy, targeted therapies, DDR therapies, radiotherapy, and immunotherapy. Finally, emerging delivery systems such as "nanosensitizers" as radiotherapy enhancers are currently in development. Future Directions: While approaches designed to induce ROS have shown considerable promise in selectively targeting cancer cells and dealing with resistance to conventional therapies, most are still in early phases of development and challenges remain. Further research should endeavor to refine treatment strategies, optimize drug combinations, and identify predictive biomarkers of ROS-based cancer therapies. Show less