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18 recordsLinked to original sources
PubMed2024

PARP1 UFMylation ensures the stability of stalled replication forks.

The S-phase checkpoint involving CHK1 is essential for fork stability in response to fork stalling. PARP1 acts as a sensor of replication stress and is required for CHK1 activation. However, it is unclear how the activity of PARP1 is regulated. Here, we found that UFMylation is required for the efficient activation of CHK1 by UFMylating PARP1 at K548 during replication stress. Inactivation of UFL1, the E3 enzyme essential for UFMylation, delayed CHK1 activation and inhibits nascent DNA degradation during replication blockage as seen in PARP1-deficient cells. An in vitro study indicated that PARP1 is UFMylated at K548, which enhances its catalytic activity. Correspondingly, a PARP1 UFMylation-deficient mutant (K548R) and pathogenic mutant (F553L) compromised CHK1 activation, the restart of stalled replication forks following replication blockage, and chromosome stability. Defective PARP1 UFMylation also resulted in excessive nascent DNA degradation at stalled replication forks. Finally, we observed that PARP1 UFMylation-deficient knock-in mice exhibited increased sensitivity to replication stress caused by anticancer treatments. Thus, we demonstrate that PARP1 UFMylation promotes CHK1 activation and replication fork stability during replication stress, thus safeguarding genome integrity.

DNA Replication↗
PubMed2026

DNA-PKcs and PARP1 at the interface between DNA damage responses and cGAS-STING signaling: context-dependent roles and therapeutic implications.

AIMS: To explore the roles of DNA-dependent protein kinase catalytic subunit (DNA-PKcs) and poly(ADP-ribose) polymerase 1 (PARP1) in both the DNA damage repair (DDR) pathway and the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway mediated immune response, and to analyze the therapeutic potential of their inhibitors. METHODS: This is a review article synthesizing recent findings on the functions of DNA-PKcs and PARP1 in DDR, their context-dependent effects on the cGAS-STING pathway and the therapeutic mechanisms of their inhibitors. RESULTS: DNA-PKcs and PARP1 are key components of two major DDR mechanisms. Beyond their canonical repair functions, both factors significantly regulate the cGAS-STING pathway, a central mediator linking cytoplasmic DNA and the type I interferon response. CONCLUSION: DNA-PKcs and PARP1 connect genome maintenance with innate immune signaling through context-dependent mechanisms. Targeting these proteins represents a promising strategy for modulating cGAS-STING signaling and improving disease treatment.

Humans↗
PubMed2026

Cell type-dependent induction of type I interferon and PARP1 activation in astrocytes and neurons during chikungunya virus infection.

Chikungunya virus, a mosquito-borne alphavirus, causes fever, rash, arthritis, and neurological disorders. Its non-structural protein 3 harbors a macrodomain, a key neurovirulence factor that removes adenosine diphosphate ribose from ADP-ribosylated substrates. Notably, chikungunya virus infection results in distinct ADP-ribosylation patterns and non-structural protein 3 macrodomain-mediated replication dynamics in astrocytes and neurons. Understanding the connection between ADP-ribosylation and the activation of innate immunity, particularly interferon release, is key to elucidating how the cellular immunological state influences ADP-ribosylation, an understudied post-translational modification during viral infection. Here, murine astrocytic (C8-D1A) and neuronal (NSC-34) cells were infected with chikungunya virus to profile transcript and protein expression of innate immune mediators and type I IFNs. The role of PARP1 in global ADP-ribosylation patterns was assessed using PARP-specific inhibitors and genetic depletion approaches. Our investigations revealed that neuronal chikungunya virus infection induces ADP-ribosylation through PARP1 activation, driven by caspase-3-mediated apoptosis, without transcriptionally activating PARPs. In contrast, astrocytic infections showed minimal ADP-ribosylation despite transcriptional activation of interferon-stimulated PARPs. Neurons exhibited limited innate immune response gene transcriptional activity, whereas astrocytes demonstrated strong upregulation of genes essential for pattern recognition receptor activation, thus enhancing double-stranded RNA sensing and increasing type I interferon production during infection. We posit that PARP1 activation and type I IFN response differentially regulate ADP-ribosylation in chikungunya virus-infected neural cells in a cell type-dependent manner.IMPORTANCEChikungunya virus is an emergent mosquito-borne alphavirus increasingly associated with neurological infection and subsequent long-term disabilities. Its continued global spread and recurrent outbreaks underscore its significant pandemic potential and the urgent need for effective countermeasures. Chikungunya virus showcases distinct, cell-type dependent replication dynamics within astrocytes and neurons, two major permissive cerebral cell types. However, understanding of the immunological basis of such cell type-specific infection dynamics remains limited, yet is necessary to elucidate virus pathogenesis within the brain and thus identification of downstream drug targets. Our study characterized two distinctly activated innate immunological pathways in chikungunya virus-infected astrocytes versus neurons, thus significantly contributing to molecular understanding cell type-specific chikungunya virus neurovirulence on a molecular level.

Animals↗
PubMed2024

Angiopoietin-like protein 8 directs DNA damage responses towards apoptosis by stabilizing PARP1-DNA condensates.

Upon genotoxic stresses, cells employ various DNA damage responses (DDRs), including DNA damage repair or apoptosis, to safeguard genome integrity. However, the determinants among different DDRs choices are largely unknown. Here, we report angiopoietin-like protein 8 (ANGPTL8), a secreted regulator of lipid metabolism, localizes to the nucleus and acts as a dynamic switch that directs DDRs towards apoptosis rather than DNA repair after genotoxin exposure. ANGPTL8 deficiency alleviates DNA damage and apoptosis in cells exposed to genotoxins, as well as in the liver or kidney of mice injured by hepatic ischemia/reperfusion or cisplatin treatment. Mechanistically, ANGPTL8 physically interacts with Poly (ADP-ribose) polymerase 1 (PARP1), in a PARylation-independent manner, and reduces the fluidity of PARP1-DNA condensates, thereby enhancing the pro-apoptotic accumulation of PARP1 and PAR chains on DNA lesions. However, the transcription of ANGPTL8 is gradually decreased following genotoxin treatment, partly due to downregulation of CCAAT enhancer binding protein alpha (CEBPA), presumably to avoid further cytotoxicity. Together, we provide new insights by which genotoxic stress induced DDRs are channeled to suicidal apoptosis to safeguard genome integrity.

Animals↗
PubMed2026

USP10-SIRT6-PARP1 axis drives keratinocyte senescence and skin photoaging under chronic UVA exposure.

Chronic exposure to ultraviolet A (UVA) radiation is the principal environmental driver of skin photoaging, yet the upstream molecular events that commit irradiated keratinocytes to senescence remain poorly understood. Here we show that SIRT6, an NAD+-dependent protein deacetylase with established roles in genome maintenance and organismal longevity, functions as a central gatekeeper of keratinocyte homeostasis under photic stress. Using a chronic UVA irradiation model in mice together with cultured human keratinocytes, we demonstrate that UVA inflicts extensive DNA damage and G2/M cell-cycle arrest, accompanied by selective depletion of SIRT6 among all sirtuin family members. Mechanistically, UVA suppresses the deubiquitinase USP10 at both transcriptional and post-transcriptional levels, thereby licensing ubiquitin-dependent proteasomal degradation of SIRT6. The resulting SIRT6 deficiency unleashes hyperactivation of the DNA-damage sensor PARP1, amplifying genomic injury signaling and driving keratinocytes into irreversible senescence with concomitant elaboration of a broad pro-inflammatory secretory programme encompassing chemokines and cytokines. Pharmacological reactivation of SIRT6 with the selective agonist UBCS039 reverses epidermal hyperplasia, attenuates DNA damage and senescence marker accumulation, and suppresses inflammatory mediator induction both in vivo and in vitro, establishing SIRT6 loss as a causal rather than correlative event. Furthermore, molecular docking and functional validation identify osthole, a plant-derived coumarin from the medicinal herb Cnidium monnieri, as a candidate SIRT6-engaging compound that counteracts UVA-induced senescence and inflammation in keratinocytes. Collectively, these findings define a USP10-SIRT6-PARP1 signaling axis whose disruption underlies cutaneous photoaging and suggest that SIRT6-directed strategies may offer therapeutic benefit against UV-driven tissue degeneration.

Animals↗
PubMed2025

NR2F6 regulates Temozolomide resistance in glioma via the E2F2-PARP1 pathway.

BACKGROUND: Glioma is the most common primary malignant brain tumor in adults. Temozolomide (TMZ) represents a standard-of-care chemotherapeutic agent in glioblastoma (GBM). However, the development of drug resistance constitutes a significant hurdle in the treatment of malignant glioma. Elucidating the mechanisms of temozolomide (TMZ) resistance in glioma is of critical clinical importance for improving patient prognosis and developing novel therapeutic strategies. METHODS: We obtained RNA sequencing (RNA-seq) data of 648 glioma samples from The Cancer Genome Atlas (TCGA) and 325 samples from the Chinese Glioma Genome Atlas (CGGA) as study cohorts. Additionally, we validated the expression characteristics of the NR2F6 gene in our in-house cohort of glioma patients. Furthermore, we investigated the potential mechanism of NR2F6 in TMZ resistance in glioma by constructing TMZ-resistant cell lines in vitro. Statistical analyses and graphical work were primarily performed using R language and GraphPad Prism software. RESULTS: We observed a significant upregulation of NR2F6 expression in high-grade gliomas, which is associated with an unfavorable prognosis in patients. Concurrently, our findings revealed a significant upregulation of NR2F6 in drug-resistant cells, which induced TMZ resistance in glioma cells via the E2F2-PARP1 axis. CONCLUSION: In brief, NR2F6, as a nuclear transcription factor, enhances the transcription of E2F2.The increased expression of E2F2 enhances PARP1 expression, which in turn facilitates TMZ-mediated DNA damage repair, thereby diminishing glioma sensitivity to TMZ.

Journal Article↗
PubMed2025

Poly(ADP-ribose) Polymerase 1 Deficiency Attenuates Amyloid Pathology, Neurodegeneration, and Cognitive Decline in a Familial Alzheimer's Disease Model.

Poly(ADP-ribose) (PAR) polymerase-1 (PARP1) has been implicated in DNA damage responses and neuroinflammation in Alzheimer's disease (AD), yet its role in amyloid-β (Aβ) pathology remains unclear. Here, we show that PARP1 activation drives Aβ pathology and neurodegeneration. Using a sensitive ELISA, we observed significantly elevated PAR levels in the cerebrospinal fluid (CSF) of patients with mild cognitive impairment (MCI) and AD compared to controls. In vitro, oligomeric Aβ1-42 activated PARP1 and induced DNA damage, while genetic or pharmacological inhibition of PARP1 conferred neuroprotection. In vivo, PARP1 knockout in the 5XFAD mouse model of amyloidosis led to reduced amyloid plaque burden, preserved synaptic and neuronal integrity, attenuated glial activation and neuroinflammation, and rescued cognitive deficits. Mechanistically, PARP1 deficiency decreased amyloid precursor protein (APP) and BACE1 levels, altered γ-secretase complex composition, and enhanced Aβ degradation via neprilysin. These findings position PARP1 as a critical mediator of Aβ toxicity and neurodegeneration, suggesting its inhibition as a promising therapeutic strategy for AD.

Alzheimer’s disease↗
PubMed2026

Integrative proteomics reveals MSH6 to modulate PARP inhibitor sensitivity in BRCA1/2-proficient ovarian cancer.

Ovarian cancer remains a leading cause of gynecologic cancer-related deaths worldwide. Deficiencies in BRCA1/2 are well-established biomarkers that predict sensitivity to poly(ADP-ribose) polymerase inhibitors (PARPis). However, emerging evidence indicates that a subset of BRCA-proficient tumors also responds to PARPi therapy, suggesting the presence of additional molecular mechanisms. We hypothesized that the composition of the PARP1 protein complex and PARylation-mediated signaling contribute to PARPi response in BRCA-proficient HGSOC. We assessed PARPi response across a panel of BRCA-proficient ovarian cancer cell lines and identified distinct sensitive and resistant groups. Chemical proteomics with rucaparib revealed different PARP1 complexes including higher enrichment of MSH6 in sensitive cells. Co-immunoprecipitation analyses further confirmed differential assembly of PARP1-MSH6-PARP2 complexes between sensitive and resistant models. To explore PARylation signaling, we performed ADP-ribosylation proteomics using clickable NAD⁺ analogs, revealing distinct PARylation profiles between sensitive and resistant cell lines. CHAF1A, a known MSH6 interactor and PARP1 substrate, showed more pronounced reduction in ADP-ribosylation in PARPi-sensitive cells. Targeting MSH6 using CRISPR or siRNA decreased PARPi sensitivity. In addition, mTOR signaling was reduced in sensitive, but increased in resistant cells, following rucaparib treatment. Notably, MSH6 knockdown led to increased CHAF1A expression regardless of rucaparib treatment. Importantly, knockdown of CHAF1A significantly impaired cell viability, especially in A2780 cells, and suppressed mTOR signaling, suggesting that CHAF1A acts downstream of MSH6 to regulate the mTOR axis. Furthermore, co-treatment with mTORC1 inhibitors enhanced the cellular effects of rucaparib in resistant cells, suggesting a therapeutic potential of targeting downstream mTOR effectors to overcome intrinsic resistance. In conclusion, this study identifies the PARP1-MSH6 interaction to modulate PARPi sensitivity via CHAF1A-mTOR signaling in BRCA-proficient ovarian cancer. By integrating chemical proteomics and ADP-ribosylation proteomics, we delineate the interplay between PARP1 complex composition and signaling dynamics, highlighting MSH6 as a critical modulator of PARPi response and potential biomarker to enhance therapeutic efficacy in BRCA-proficient HGSOC.

Humans↗
PubMed2017

Small-Molecule Inhibitors Targeting DNA Repair and DNA Repair Deficiency in Research and Cancer Therapy.

To maintain stable genomes and to avoid cancer and aging, cells need to repair a multitude of deleterious DNA lesions, which arise constantly in every cell. Processes that support genome integrity in normal cells, however, allow cancer cells to develop resistance to radiation and DNA-damaging chemotherapeutics. Chemical inhibition of the key DNA repair proteins and pharmacologically induced synthetic lethality have become instrumental in both dissecting the complex DNA repair networks and as promising anticancer agents. The difficulty in capitalizing on synthetically lethal interactions in cancer cells is that many potential targets do not possess well-defined small-molecule binding determinates. In this review, we discuss several successful campaigns to identify and leverage small-molecule inhibitors of the DNA repair proteins, from PARP1, a paradigm case for clinically successful small-molecule inhibitors, to coveted new targets, such as RAD51 recombinase, RAD52 DNA repair protein, MRE11 nuclease, and WRN DNA helicase.

DNA Helicases↗
PubMed2025

The cGAS-STING pathway is a master regulator of OCT4 expression in persistent sarcoma cells and enhances cellular immunotherapy with NK and CIK lymphocytes.

Advanced sarcomas have a poor prognosis and limited therapeutic options. Disease recurrence is caused by persistent cells that survive drug treatments. The alkylating agent trabectedin, when combined with the poly (ADP-ribose) polymerase 1 (PARP1) inhibitor olaparib, exhibits variable antitumor effects in advanced sarcomas. In this study, we demonstrate that the expression of the transcription factor OCT4 is upregulated in persistent cells that survive treatment with trabectedin and olaparib, through the cGAS-STING-IRF3-IFNβ pathway. This route also leads to the upregulation of natural killer (NK) and cytokine-induced killer (CIK) lymphocyte activating ligands. These molecular events enhance the antitumor efficacy of immunotherapy with NK and CIK cells, targeting both the bulk population and residual drug-tolerant cells. In conclusion, the activation of the cGAS-STING pathway has a double-edged effect, enriching the OCT4+ persistent cell population while increasing the expression of NK/CIK ligands. The addition of olaparib to trabectedin potentiates the cGAS-STING pathway activation and the upregulation of NKG2DLs, while simultaneously counteracting the OCT4 overexpression. Therefore, sequential treatment with trabectedin and olaparib followed by NK/CIK immunotherapy represents a promising strategy against advanced sarcomas and warrants further investigation.

Humans↗
PubMed2026

The TyrRS cascade: circadian gating of neuronal DNA repair and its collapse in aging.

Age-related neurodegenerative diseases are characterized by progressive DNA damage in post-mitotic neurons against a backdrop of deteriorating circadian rhythms, yet the molecular link between these conjoined features of brain aging remains unclear. We propose the TyrRS cascade as that link: a signaling architecture in which the noncanonical nuclear functions of tyrosyl-tRNA synthetase (TyrRS/YARS1) schedule neuronal genome maintenance across the day through three coregulated streams, PARP1-mediated damage sensing, TRIM28/NuRD heterochromatin maintenance, and LIN9/DREAM control of a 67-gene repair archive. The model's central commitment is that the operative variable is oscillation amplitude rather than mean activity. We argue that as serum tyrosine rises with age and circadian amplitude flattens, these insults compound into a double-hit collapse that traps the cascade in a frozen-intermediate state, which bulk-tissue assays misread as elevated mean activity when the oscillation has merely lost its excursion. Placed in dialogue with oscillatory-clearance models of sleep, the cascade and the glymphatic system emerge as complementary, compartment-separated arms of a single sleep-dependent maintenance program that fail together through amplitude collapse, yielding a signature of preserved phase architecture with reduced dynamic range. Reframing neurodegeneration as a scheduling failure rather than a capacity failure carries three translational consequences: Pulsatile, phase-aligned dosing should outperform sustained-release pharmacology, which is predicted to flatten the rhythm it aims to restore; demonstrating target engagement will require phase-resolved rather than single-timepoint measurement; and because both arms fail together, combined restoration of intracellular repair and extracellular clearance should outperform single-arm intervention.

Alzheimer’s disease↗
PubMed2026

Alternative End Joining Dependency Imposed by miR-21-5p Defines Radiation Resistance and a Targetable Vulnerability in Oral Squamous Cell Carcinoma.

PURPOSE: Clinical control of oral squamous cell carcinoma (OSCC) is constrained by heterogeneous radiosensitivity driven by divergent DNA damage response programs. The architecture and functional contribution of alternative end joining (Alt-EJ), an error-prone DNA double-strand break (DSB) repair pathway frequently upregulated in cancer, to radiation resistance remains poorly defined. METHODS AND MATERIALS: We profiled microRNAs in radioresistant OSCC clones and performed multiomic integration across an institutional OSCC cohort, an external OSCC cohort from the Gene Expression Omnibus, The Cancer Genome Atlas pan-cancer tumors, and cell lines characterized by Sanger Genomics of Drug Sensitivity in Cancer to infer DNA damage response characteristics, genomic scar features, drug sensitivity, and radiation therapy outcomes. DSB repair capacity and pathway usage were validated using functional assays, including Alt-EJ reporters and droplet digital PCR quantification of microhomology-mediated repair events. Core Alt-EJ effectors such as PARP1 and POLQ were perturbed genetically and pharmacologically. Therapeutic efficacy of PARP or POLQ inhibition with or without irradiation was tested in a syngeneic OSCC model, followed by bulk tumor transcriptomics to assess pathway engagement. RESULTS: Upregulation of miR-21-5p was not only selectively detected in radioresistant OSCC, but also modulated radiosensitivity in vitro and in vivo, and was associated with inferior postradiation therapy survival. A calibrated miR-21-5p target-gene signature tracked Alt-EJ activity across patient and mouse tumors and cancer cell lines, correlated with microhomology-mediated indels and broader genomic scarring, and predicted sensitivity to clinically available PARP inhibitors. Functionally, enforced miR-21-5p expression increased Alt-EJ usage and accelerated DSB repair, whereas inhibition or depletion of key Alt-EJ effectors reduced repair efficiency and restored radiosensitivity. In vivo, Alt-EJ targeting with PARP or POLQ inhibitor abrogated miR-21-5p-driven radiation resistance; transcriptomic profiling supported suppression of Alt-EJ programs as the operative mechanism. CONCLUSIONS: These findings establish a mechanistic link between miR-21-5p activity and Alt-EJ dependence, provide a clinically deployable signature to identify Alt-EJ-dependent OSCC, and support rational combinations of Alt-EJ targeting agents with radiation therapy to overcome treatment failure and advance precision radiation oncology.

MicroRNAs↗
PubMed2026

Low-pass whole-genome sequencing reveals genomic diversity and ecotype-specific adaptation in indigenous Tigrayan chickens.

Indigenous chickens play a critical role in food security and climate resilience in smallholder systems, yet their genomic diversity and adaptive potential remain insufficiently characterised. This study employed low-pass whole-genome sequencing (LP-WGS; 0.2-1.99×) to investigate genomic diversity, population structure, inbreeding and candidate environment-associated genomic variation in 33 chickens from highland, midland, and lowland agroecologies in the Tigray region of northern Ethiopia. After imputation and stringent filtering, 23.4 million high-confidence SNPs were retained, including ~ 17% novel variants, indicating substantial uncharacterised genetic diversity in these populations. SNP density (13.8 ± 8.6 SNPs/kb) was comparable to values reported from high-coverage Ethiopian chicken datasets, demonstrating the suitability of LP-WGS for population genomics in resource-limited settings. Marked differences in genomic diversity were observed among ecotypes: midland chickens showed the highest nucleotide diversity (π = 0.00267), followed by lowland (π = 0.00233), whereas highland chickens showed the lowest diversity (π = 0.00203) and elevated genomic inbreeding (FROH and FHOM ≈ 0.18). Population structure analyses revealed clear genetic separation among ecotypes. PCA (13.91% variation explained) distinguished lowland chickens along PC1 and separated highland from midland along PC2, while ADMIXTURE and FST patterns supported three major ancestral genomic backgrounds. Functional annotation of private missense variants uncovered distinct adaptive signatures reflecting the contrasting agroecological conditions. Highland chickens showed enrichment of candidate genes potentially involved in physiological processes relevant to high-altitude environments, including cold response, angiogenesis, cardiovascular regulation and metabolic homeostasis (eg., PARP1, ACOX2, ITGB3, EDNRB, SOX8, and SOX10). Midland chickens exhibited candidate signals of selection in genes with known roles in innate antiviral immunity, bacterial defence and inflammatory regulation (eg., BAK1, CLSTN1, CYSLTR1, CYSLTR2, CXCR7, GIPR, DSCAM, GDAP1, TLR3, TLR4, TLR7, IFIH1, ADORA1, EPHB1, and TMPRSS2). Lowland chickens displayed candidate variants associated with heat-stress response, DNA damage repair, oxidative balance and cardiovascular support under extreme temperatures (e.g., MLH1, BDKRB1, GPR19, FLT1, CCL18, TGM2, and RAMP3). Overall, the results indicate substantial genomic differentiation among ecotypes and suggest candidate environment-associated genetic divergence across Tigray's diverse agroecological zones. These populations may represent important reservoirs of adaptive genetic variation for climate-resilient poultry breeding, warranting further functional validation and conservation-oriented management.

Animals↗
PubMed2026

PARG inhibition reduces ssDNA levels and limits RPA loading upon replication fork collapse.

Poly(ADP-ribosyl)ation (PARylation) is a transient post-translational modification catalyzed by PARP enzymes and reversed by PARG. PARG inhibition causes sustained PARylation and is being explored as an anticancer strategy, but its cellular consequences remain incompletely understood. Here, we examine how persistent PARylation influences cellular responses to replication stress and DNA damage. We show that sustained PARylation reduces phosphorylated and chromatin-bound RPA most strongly under fork-stalling conditions that progress toward fork collapse. This effect requires PARP1 activity and is restrained by intact ATR-CHK1 signaling, as checkpoint inhibition renders otherwise resistant cells permissive for PARG inhibitor-associated phosphorylated RPA loss from the chromatin. The reduction of RPA phosphorylation is not dependent on BRCA1 and it is not accompanied by increased RAD51 loading. Instead, reduced chromatin-bound RPA coincides with decreased exposed ssDNA. Our results identify a checkpoint-dependent fork-collapse state in which sustained PARylation limits ssDNA and RPA levels.

Replication Protein A↗
PubMed2016

A mechanism for 1,4-Benzoquinone-induced genotoxicity.

Benzene is a common environmental toxin and its metabolite, 1-4-Benzoquinone (BQ) causes hematopoietic cancers like myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). BQ has not been comprehensively assessed for its impact on genome maintenance, limiting our understanding of the true health risks associated with benzene exposure and our ability to identify people with increased sensitivity to this genotoxin. Here we analyze the impact BQ exposure has on wild type and DNA repair-defective mouse embryonic stem (ES) cells and wild type human cells. We find that double strand break (DSB) repair and replication fork maintenance pathways including homologous recombination (HR) and Fanconi anemia (FA) suppress BQ toxicity. BQ-induced damage efficiently stalls replication forks, yet poorly induces ATR/DNA-PKCS responses. Furthermore, the pattern of BQ-induced γH2AX and 53BP1foci is consistent with the formation of poly(ADP-ribose) polymerase 1 (PARP1)-stabilized regressed replication forks. At a biochemical level, BQ inhibited topoisomerase 1 (topo1)-mediated DNA ligation and nicking in vitro; thus providing mechanism for the cellular phenotype. These data are consistent with a model that proposes BQ interferes with type I topoisomerase's ability to maintain replication fork restart and progression leading to chromosomal instability that has the potential to cause hematopoietic cancers like MDS and AML.

Animals↗
PubMed2026

Prognostic significance of DNA damage response-related markers in esophageal squamous cell carcinoma using machine learning approaches.

BACKGROUND: Esophageal squamous cell carcinoma (ESCC) lacks reliable prognostic biomarkers. Homologous recombination deficiency (HRD) has been implicated in genomic instability across multiple cancers, but its prognostic significance in ESCC remains unexplored. This study aimed to evaluate HRD score as a prognostic biomarker and develop a machine learning-based predictive model for ESCC. METHODS: Transcriptomic and clinical data from 78 ESCC patients were obtained from The Cancer Genome Atlas (TCGA) and randomly split into training (70%) and test (30%) cohorts. Prognostic models were constructed using 112 machine learning algorithm combinations based on DNA damage response (DDR)-related genes. Gene set enrichment analysis (GSEA), somatic mutation profiling, and immune cell infiltration estimation via CIBERSORT were performed to characterize HRD-associated molecular features. RESULTS: High HRD scores were significantly associated with poorer overall survival (P<0.05). Among 112 algorithm combinations, the survival support vector machine (Survival-SVM) model demonstrated optimal performance [training concordance index (C-index): 0.741; test C-index: 0.708], identifying six hub genes: PARP1, MBD4, TELO2, NSMCE3, SMUG1, and BABAM1. A nomogram incorporating risk score (RS) and clinical variables achieved strong predictive accuracy for 1- to 3-year survival [area under the curve (AUC) >0.7]. High-HRD tumors exhibited distinct mutational patterns (TP53 and TTN) and enriched glutathione metabolism and cytochrome P450 pathways. Immune infiltration analysis revealed significant differences in plasma cell and neutrophil infiltration between risk groups (P<0.05), suggesting HRD-associated immune microenvironment remodeling. CONCLUSIONS: We developed a novel HRD-based prognostic model incorporating six DDR-related genes that demonstrates robust predictive performance in ESCC. HRD score is identified as an independent prognostic factor associated with genomic instability, immune microenvironment alterations, and clinical outcomes. These findings provide a theoretical basis for personalized treatment strategies, including potential applications of PARP inhibitors and immunotherapy in ESCC.

Esophageal squamous cell carcinoma (ESCC)↗
PubMed2026

Uncovering ShuangZi Powder's Anti-Ovarian Cancer Mechanism: A Systems Biology and Experimental Approach.

INTRODUCTION: This study investigated the anti-ovarian cancer (OC) effects of Shuangzi Powder (SZP) and its regulatory impact on the tumor microenvironment. METHOD: This study employed systems biology approaches, integrating molecular docking and experimental validation, to explore the pharmacological mechanisms of SZP in OC treatment. To identify potential bioactive compounds and target genes of SZP, network pharmacology, protein- protein interaction network analysis,.Gene Ontology (GO) analysis, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment were conducted. RESULTS: Among the 11 bioactive ingredients identified in SZP, 1,767 potential therapeutic targets were predicted, while 2,637 differentially expressed genes were found to be associated with OC. KEGG pathway analysis revealed significant enrichment in pathways related to cancer, apoptosis, the PI3K-Akt signaling pathway, and the PD-L1/PD-1 checkpoint pathway. Treatment of A2780 cells with &#x3b2;,&#x3b2;-Dimethylacrylshikonin (DMAS) inhibited cell viability, migration, and invasion. Moreover, DMAS downregulated the expression of cell cycle- and apoptosis-related genes (CCNB1, CHEK1, CCNE1, and PARP1) and upregulated the immune checkpoint gene PD-L1. DISCUSSION: These findings indicate that multiple components, targets, and pathways are involved in OC treatment by SZP. CONCLUSION: DMAS, one of the bioactive ingredients of SZP, was predicted and preliminarily validated to exert inhibitory effects on OC cells, mainly through the regulation of the cell cycle, apoptosis, and immune response, as demonstrated by molecular docking and experimental analyses.

Ovarian Neoplasms↗
PubMed2026

Lactylome Reprogramming Mediates Therapeutic Response and Adaptation to Neoadjuvant Chemotherapy in Esophageal Squamous Cell Carcinoma.

Esophageal squamous cell carcinoma (ESCC) exhibits high prevalence in China and poor prognosis despite neoadjuvant chemotherapy (NACT), with significant chemoresistance development. Tumor-associated metabolic reprogramming and NACT-induced cellular stress promote lactate accumulation, which serves as a precursor for lysine lactylation (Kla), a post-translational modification potentially regulating cancer progression. We hypothesized that systematic characterization of the lactylome in response to NACT could reveal critical molecular mechanisms underlying treatment and identify new therapeutic vulnerabilities in ESCC. Herein, through comprehensive proteomic and lactylome profiling of tumor and adjacent normal adjacent tissues from 31 ESCC patients (with or without NACT treatment), we identified 8281 proteins and 1836 Kla sites across 62 samples. NACT induced substantial lactylome alterations with 307 differentially expressed Kla sites predominantly in nonhistone proteins involved in DNA damage response and metabolic pathways. Our data revealed that while NACT-induced suppression of energy metabolism, coupled with upregulated 3-hydroxy-3-methylglutaryl reductase degradation 1 complex expression, may exert potential proapoptotic effects, the activation of ribosome biogenesis and increased nucleoprotein lactylation triggered tumor-protective mechanisms. Mechanistically, we demonstrated that DNA damage and elevated lactate levels induced poly(ADP-ribose) polymerase 1 K654 lactylation, enhancing its enzymatic activity and augmenting poly(ADP-ribosyl)ation of downstream targets, potentially playing a pivotal role in chemotherapy resistance-associated pathways. This comprehensive tissue-level landscape of Kla dynamics in ESCC response to chemotherapy establishes Kla as a critical regulatory mechanism in treatment response, potentially offering novel therapeutic targets and predictive biomarkers for personalized treatment strategies.

Humans↗