Epigallocatechin gallate (EGCG) exerts cardioprotective effects on acute myocardial infarction through multiple pathways. However, the clinical application of EGCG is limited because of its instability under physiological conditions and low bioavailability. In this study, poly(lactic-co-glycolic acid) was used as a drug carrier to prepare EGCG nanoparticles (NPs), then an EGCG targeting drug delivery system was designed by modifying with cardiac homing peptide. We constructed a preparation route combining the double-emulsion solvent evaporation method and the carbodiimide method. By optimizing the preparation process, the particle size of the EGCG NP was reduced, and the dispersibility was improved. In addition, the established preparation procedure uses safe and low-toxicity reagents, requires no strict temperature control or specialized instrumentation, and therefore significantly reduces the technical difficulty of large-scale industrial production. EGCG-poly(lactic-co-glycolic acid)-cardiac homing peptide had myocardial targeting and good safety in the 3‑(4,5‑dimethyl‑2‑thiazolyl)‑2,5‑diphenyl‑2H‑tetrazolium bromide (MTT) cytotoxicity test, and alleviated acute myocardial infarction by regulating apoptosis-related protein expression in a dose-dependent manner. Compared with EGCG monomer, EGCG-poly(lactic-co-glycolic acid)-cardiac homing peptide achieved a better therapeutic effect. This study provides a new strategy for promoting the application of EGCG in the clinical treatment of acute myocardial infarction. SIGNIFICANCE STATEMENT: This study develops cardiac homing peptide-modified poly(lactic-co-glycolic acid) nanoparticles to enable targeted delivery of epigallocatechin gallate for acute myocardial infarction therapy. By overcoming the inherent instability and poor bioavailability of epigallocatechin gallate, this scalable nanoplatform achieves superior cardioprotection through regulated apoptosis and exhibits excellent safety in the MTT cytotoxicity test. These findings establish a clinically translatable strategy for targeted drug delivery in the treatment of cardiovascular disease.

Alzheimer's disease (AD) is a neurodegenerative disorder marked by cognitive decline, where females account for 60% of diagnosed cases. AD is featured by β-amyloid deposition, which influences the activity of M1 muscarinic acetylcholine receptors (M1 mAChRs) that are essential for memory and learning. We previously demonstrated that VU0486846, a M1 mAChR positive allosteric modulator, improves cognitive function in AD mice by ameliorating β-amyloid pathology. However, it remains unclear how changes in M1 mAChR signaling and subcellular localization in AD brain influences its mechanism and how this differs between sexes. Nine-month-old male and female APPswe/PSEN1ΔE9 (APP/PS1) and wild-type mice were treated with VU0486846 (10 mg/kg/day) or vehicle via drinking water for 8 weeks. Elevated extracellular signal-regulated kinase 1/2 signaling, a plausible driver for β-amyloid pathology, was observed in female but not male APP/PS1 mice cortices, whereas VU0486846 mitigated this change. Additionally, VU0486846 enhanced the phosphorylation of the neuronal transcription factor cAMP response element-binding protein and increased the level of c-Fos, which regulate neuronal survival, in female wild-type and APP/PS1 mice only. In contrast, only male APP/PS1 mice exhibited increased levels of p62/SQSTM1 and decreased glycogen synthase kinase-3β activity, indicative of impaired autophagic flux, a change that was ameliorated by VU0486846 treatment. In subcellular fractions obtained from mice cortices, VU0486846 only increased cytosolic M1 mAChR level in female wild-type and APP/PS1 mice but not in males. Our findings indicate that M1 mAChR signaling is disrupted in APP/PS1 mice in a sex-dependent manner. VU0486846 enhances prosurvival signaling in females, potentially by increasing the cytosolic pool of M1 mAChRs, while modulating autophagy pathways in males, highlighting a sex-specific mechanism of action and underscoring its therapeutic potential. SIGNIFICANCE STATEMENT: The study highlights the sex-specific role of M1 muscarinic acetylcholine receptor (M1 mAChR) in Alzheimer's disease (AD) pathophysiology, providing evidence that the ability of M1 mAChR positive allosteric modulation to alleviate β-amyloid pathology occurs through distinct mechanisms. It rescues neuronal activity in females, which could be linked to enhanced cytosolic receptor pooling, while restoring autophagic flux in males. The study also reinforces the therapeutic potential of M1 mAChR positive allosteric modulators and supports the development of sex-tailored interventions for AD.

Therapies capable of resolving rheumatoid arthritis (RA)-associated lung disease, particularly in the setting of environmental exposures, are lacking. This study sought to determine whether blocking interleukin (IL)-33 in a murine model of RA-associated lung disease induced by combined collagen-induced arthritis (CIA) and repeated inhalant lipopolysaccharide (LPS) exposures could be advantageous. Arthritis prone male DBA/1J mice received CIA (vs saline) injections (days 1 and 21) plus intranasal LPS (100 ng) or saline daily for 4 weeks and were subsequently treated with 5 doses of anti-IL-33 (10 mg/kg) or isotype over 11 days. Anti-IL-33 therapy significantly (P < .05) mitigated several CIA+LPS-induced effects. Anti-IL-33 reduced arthritis inflammatory score by 76% and serum acute phase reactant pentraxin-2 by 70% and reversed weight loss induced by CIA+LPS coexposure. Anti-IL-33 reduced CIA+LPS-induced antimalondialdehyde acetaldehyde but not anticitrullinated autoantibodies in serum and reduced serum levels of inflammatory mediators. Lung cell infiltrates induced by coexposure, including neutrophils, activated lung macrophages, transitional monocytes-macrophages, monocytic-like cells, and dendritic cells, were reduced with anti-IL-33. Anti-IL-33 also reduced CIA+LPS-induced lung levels of chemokines involved in monocyte-macrophage recruitment and fibrotic/repair mediators collagen deposition, IL-33 expression, inflammatory CC motif chemokine receptor 2[+] monocytes/macrophages, and airway Muc5b immunostaining induced by CIA+LPS were reduced with anti-IL-33. CIA+LPS-induced lung expression of post-translational modified autoantigens including citrullinated and malondialdehyde acetaldehyde and its common substrate, vimentin, was reduced with anti-IL-33 treatment. Blocking IL-33 was beneficial in hastening lung recovery after establishment of disease by coexposure to CIA+LPS and potentially represents a novel therapeutic approach in RA-associated lung disease. SIGNIFICANCE STATEMENT: Blocking the interleukin (IL)-33 signaling pathway after the establishment of, but not during the induction of, rheumatoid arthritis (RA)-associated lung disease, as modeled by coexposure of collagen-induced arthritis with repetitive inhalant endotoxin, demonstrated beneficial consequences in reducing inflammatory joint, systemic, and lung disease. Treatment with anti-IL-33 agents, particularly in men with a history of environmental exposures, may represent a novel approach to reduce disease burden in humans with established RA-lung disease, underscoring an important role for the IL-33 pathway.

N-pyrrolidino (PYR) nitazenes are a subset of 2-benzylbenzimidazole opioids appearing in illicit drug markets, but there is limited information about the pharmacology of these compounds. Here, we examined the opioid-like effects of PYR nitazenes with varying alkoxy chain lengths (ie, methoxy, ethoxy, propoxy, and isopropoxy) compared with fentanyl. Opioid receptor binding and functional assays were employed to determine affinities and potencies of the compounds in vitro. Acute opioid-like effects were examined in mice, using hot plate antinociception, motor activity, and body temperature measures. PYR nitazenes displayed high affinity at the μ-opioid receptor (Ki = 1-12 nM), with weaker affinities at δ and κ sites. The compounds were potent and efficacious agonists in assays measuring μ-opioid receptor-mediated inhibition of cAMP formation (EC50 = 0.03-0.91 nM, Emax = 104%-106%) compared with fentanyl (EC50 = 0.23 nM, Emax = 100%). The nitazenes also induced β-arrestin 2 recruitment, but with weaker potencies. In mouse studies, the compounds induced dose-dependent antinociception, hyperactivity, and hypothermia. Across in vivo measures, the ethoxy, propoxy, and isopropoxy compounds (ED50 = 0.002-0.033 mg/kg) were more potent than fentanyl (ED50 = 0.081-0.178 mg/kg). The acute in vivo effects of ethoxy and isopropoxy analogs were fully or partially reversed by naloxone (0.3 mg/kg). PYR nitazenes with intermediate alkoxy chain lengths are most potent for eliciting opioid-like effects in vitro and in mice. In particular, the ethoxy, propoxy, and isopropoxy analogs are more potent than fentanyl, highlighting an elevated risk for overdose with these compounds. SIGNIFICANCE STATEMENT: The present study characterized the pharmacology of N-pyrrolidino nitazene opioids that vary by alkoxy chain length and are associated with overdose cases in humans. The ethoxy, isopropoxy, and propoxy N-pyrrolidino nitazenes were found to be more potent than fentanyl in both in vitro and in vivo assays, suggesting that these compounds pose a serious overdose risk to humans who are unknowingly exposed to the compounds in the illicit opioid supply.

α-Synuclein (α-syn) is a presynaptic protein implicated in Parkinson disease and related synucleinopathies, but its physiological function remains incompletely understood. Monoamine transporters, including the dopamine transporter (DAT) and serotonin transporter (SERT), are key determinants of neurotransmitter clearance and primary targets of psychostimulant drugs. Although α-syn has been reported to interact with these transporters, its impact on transporter function remains unresolved. In the present study, we systematically manipulated α-syn expression in cellular models to determine its effects on DAT and SERT function. Overexpression of α-syn increased substrate uptake at both transporters, reflected by a selective increase in maximal transport velocity (Vmax) without significant changes in substrate affinity (KM). This effect was accompanied by elevated total DAT and SERT protein levels. Conversely, small interfering RNA-mediated knockdown or CRISPR/Cas9-mediated knockout of α-syn reduced transporter expression and decreased uptake capacity. In addition, amphetamine-induced transporter-mediated efflux was significantly attenuated in α-syn-deficient cells. These findings identify α-syn as a positive regulator of monoamine transporter expression and transport capacity. By controlling transporter abundance, α-syn modulates both substrate uptake and psychostimulant-induced reverse transport. This regulatory mechanism has important implications for monoamine homeostasis and for the pharmacological actions of transporter-targeting drugs such as D-amphetamine or 3,4-methylenedioxymethamphetamine ("ecstasy"). SIGNIFICANCE STATEMENT: The physiological role of α-synuclein (α-syn), a protein central to Parkinson disease, is not fully understood. This study demonstrates that α-syn enhances the expression and transport capacity of dopamine and serotonin transporters, thereby regulating monoamine clearance and amphetamine-induced efflux. This identifies α-syn as a key modulator of monoaminergic signaling and provides a mechanistic framework linking its normal function to disease-related alterations in neurotransmission.

The ENHANCE trials demonstrated that ensifentrine (CAS Number 1884461-72-6), an inhaled dual phosphodiesterase (PDE) 3/4 inhibitor, offers additional benefits in chronic obstructive pulmonary disease (COPD). Its bifunctional activity warrants pharmacological investigation to elucidate mechanisms behind lung function improvements and exacerbation reduction. Human bronchial tissues from COPD donors were examined after lipopolysaccharide challenge. The effects of ensifentrine on bronchial relaxation were evaluated in response to carbachol and electrical field stimulation (EFS), also in combination with long-acting muscarinic antagonist (LAMA), long-acting β2-adrenoceptor agonists (LABA), and inhaled corticosteroids (ICS). Anti-inflammatory effects were assessed by profiling cytokines, alarmins, and growth factors. Drug interactions were analyzed using the Bliss-Loewe Uncertainty Range (BLUR) model. Ensifentrine induced concentration-dependent relaxation to carbachol in both epithelium-intact and epithelium-denuded tissues (Emax 81.97 ± 6.17%, pEC50 4.86 ± 0.17) and inhibited EFS-induced contractility from 0.1 μM, with maximum reduction of 29.01% ± 2.50%. When combined with a LAMA, dual LABA/LAMA, or triple ICS/LABA/LAMA combinations, ensifentrine showed synergistic bronchorelaxant effect (overall increase in relaxation 20.47% ± 0.39%), leading to near-complete relaxation (>90%) at higher concentrations. At lower concentrations, ensifentrine reduced inflammation by 84.34% ± 8.69% in medium bronchi and 64.75% ± 8.96% in small airways; at the higher concentrations, inflammation was almost abolished (>90%), comparable to roflumilast. Drug combinations showed synergistic anti-inflammatory interactions in 31.43% of cases, mainly affecting interleukin 10, interleukin 25, granulocyte-macrophage colony-stimulating factor, and tumor necrosis factor-α. This study supports ensifentrine as an adjunct in COPD therapy, because of its dual bronchodilator and anti-inflammatory actions. Further research is warranted to optimize combination strategies to maximize clinical benefits and to identify additional activities in the target tissue. SIGNIFICANCE STATEMENT: The inhaled dual PDE 3/4 inhibitor ensifentrine emerges as a potent therapeutic option for COPD, showing remarkable bronchodilator and anti-inflammatory effects within human airways, the primary target tissue. It exhibits synergistic interactions with existing inhaler therapies, enhancing their efficacy. By demonstrating anti-inflammatory efficacy comparable to the established PDE4 inhibitor, roflumilast, our findings emphasize ensifentrine's capacity to significantly improve treatment outcomes and guide the development of optimized future combination strategies for COPD management.

Peptide hormones play a central role in maintaining metabolic homeostasis by integrating complex signaling pathways to coordinate interorgan crosstalk. Aberrant production and/or dysfunction of peptide hormones are important contributors to the pathophysiology of a cluster of interrelated chronic metabolic diseases (CMDs), including obesity, type 2 diabetes mellitus, dyslipidemia, metabolic dysfunction-associated steatotic liver disease, and cardiovascular diseases. These CMDs often co-occur, ranking among the top causes of death and disability in the rapidly aging population. Peptide hormone-based pharmacotherapies are the mainstay of treatment for these CMDs. Analogs and agonists of peptide hormones produced by classical endocrine cells, especially insulin and glucagon-like peptide-1, are cornerstones in managing diabetes and obesity. Furthermore, peptide hormones released from nonclassical endocrine organs, such as liver-secreted fibroblast growth factors 21 and growth differentiation factor 15, have emerged as highly promising therapeutic candidates for obesity-related metabolic comorbidities. These peptide hormones act synergistically and/or complementarily to exert pleiotropic metabolic benefits through their distinct receptors in different target organs/tissues. Combination pharmacotherapies with these peptide hormones are much more effective than monotherapy and hold promise to address the multimorbidity issue in patients with CMDs. This review summarizes recent advances in the pharmacoengineering and pharmacology of these peptide hormone-based long-acting analogs and coagonists and discusses their synergistic and antagonistic interactions in the treatment of CMDs. Furthermore, we highlight major challenges and future perspectives in the clinical development of multiple peptide hormone-based coagonists as safe and effective pharmacotherapy for the management of metabolic comorbidities. SIGNIFICANCE STATEMENT: This review highlights recent clinical advances in combination peptide hormone therapies for chronic metabolic diseases, emphasizing their superior efficacy over monotherapies in addressing metabolic multimorbidity. Summarizing the latest developments in long-acting analogs and coagonists of peptide hormones provides critical insights into their synergistic mechanisms, clinical potential, and future challenges, offering a comprehensive perspective for improving the management of complex metabolic disorders.

Chronic pain conditions affect a large proportion of the global population and pain has tremendous personal and economic impact, affecting quality of life and ability to work while imposing a significant burden on families and health care systems. Neurological disorders and painful conditions are frequently accompanied by chronic pain, which is often jointly diagnosed with age-related neurodegenerative diseases, however, many patients do not receive adequate treatment. This review aims to create a working framework around the issue of under-recognized/undertreated chronic pain in Alzheimer disease by offering an in-depth overview of the mechanisms driving chronic pain and how we can leverage this knowledge to advance therapeutics approaches for these patients with an emphasis on the immune system. SIGNIFICANCE STATEMENT: Chronic pain conditions are prevalent among the aging population, and they positively associate with dementia. The incidence of chronic pain is associated with neuropsychiatric symptoms of dementia and pain management should aim for effective treatments regardless of cognitive status.

Calcitonin gene-related peptide (CGRP), a neuropeptide, has been implicated in autoimmune diseases, endometriosis, tumors, and primary headaches, including migraine. The development of a novel, fast-acting CGRP receptor antagonist administered via nasal spray could address current clinical demands. PRT-064040, a novel, potent, and selective CGRP receptor antagonist, was discovered and developed by Sichuan Purity Pharmaceutical Co, Ltd. Its pharmacological characteristics were investigated through a series of experimental studies. In vitro assays, including radioligand binding and cAMP accumulation functional assays, demonstrated that PRT-064040 possesses high affinity for the human CGRP receptor (Ki = 26.67 ± 6.27 pM) and effectively inhibited human αCGRP-induced cAMP production (IC50 = 22.29 pM). The compound exhibited high selectivity within the calcitonin family member, with an IC50 of 5.38 nM for amylin receptor 1 and no inhibitory activity on other closely related receptors at concentrations up to 10 μM. In vivo efficacy was evaluated using a human αCGRP-induced dermal blood flow model in cynomolgus monkeys, in which PRT-064040 dose-dependently attenuated αCGRP-mediated dermal vasodilation. Following nasal administration in rats, brain penetration of PRT-064040 was minimal. Pharmacokinetic profiling in cynomolgus monkeys revealed rapid absorption (time to maximum concentration (Tmax) = 10-15 minutes) postnasal delivery. Collectively, these findings indicate that PRT-064040 functions as a competitive antagonist with high affinity, potency, and selectivity for the human CGRP receptor. Moreover, a potent, concentration-dependent relationship was observed between plasma levels of PRT-064040 and inhibition of αCGRP-mediated physiological effects. SIGNIFICANCE STATEMENT: This study demonstrates that PRT-064040 is a competitive antagonist exhibiting high affinity, potency, and selectivity for the human calcitonin gene-related peptide receptor. Its rapid absorption at low doses may not only facilitate a fast-onset action but also suggest a potential for reduced adverse events in clinical practice.

The kidneys are highly metabolically active organs that undergo a progressive, intrinsic decline in renal function with aging, a process that can be further exacerbated by chronic exposure to oxidative stress, inflammation, hypertension, and various toxins. Studies have shown that the prevalence of acute kidney injury and chronic kidney disease is significantly higher in the elderly. This suggests that the age-related reduction in baseline renal function, rather than advanced age itself, increases the susceptibility to and severity of these disorders after nephrotoxic insults. We comprehensively discuss the emerging recognition of shared molecular and cellular mechanisms underpinning fibrosis and cellular senescence, 2 hallmark features of functional decline seen in renal aging, acute kidney injury, and chronic kidney disease, as well as proposing the interconnection between these events. Furthermore, we highlight therapeutic strategies aimed at mitigating kidney damage and counteracting the effects of aging. These include lifestyle modifications, small-molecule inhibitors, and senotherapeutic approaches such as senolytics and senomorphics. Overall, this work aims to establish a foundation for understanding the pathogenesis of renal aging and related diseases, while also identifying promising avenues for effective therapeutic intervention. SIGNIFICANCE STATEMENT: Cellular senescence and fibrosis intersect in renal aging, acute kidney injury, and chronic kidney disease, highlighting shared pathways that may be targeted to slow disease progression and providing insights into the underlying mechanisms, current interventions, and future strategies for age-related kidney disorders.

Xylazine is an α2-adrenergic agonist typically used in as a sedative and analgesic in veterinary medicine. For some years, xylazine has been reported as an additive to fentanyl on the illicit drug market and has been associated with severe side-effects including severe ulcerations and potential amputations at the sites of injection along with an increased risk of respiratory depression and death. We recently reported that xylazine has modest κ opioid agonist activity in vitro and in vivo and asked if other α2-adrenergic agonists had similar off-target activities. To test this hypothesis, we profiled US Food and Drug Administration-approved α2-adrenergic agonists at 320 G protein coupled receptors to identify potentially deleterious and/or beneficial off-targets. Although all other tested α2-adrenergic agonists were devoid of κ opioid agonist activity, each had a distinct pattern of activity at various G protein coupled receptors and differential patterns of signaling bias at α2-receptor subtypes. These findings suggest potential molecular targets for both side-effects and therapeutic activities among known α2-adrenergic agonists. SIGNIFICANCE STATEMENT: Xylazine was recently shown to be a κ-opioid receptor agonist and we examined other US Food and Drug Administration-approved α2-agonists for κ-opioid activity. Xylazine is unique in having κ-agonist activity.

Experimental and clinical evidence continues to accumulate, supporting the critical role of dysregulated inflammation, immunity, and redox signaling in the pathophysiology of various age-related cardiometabolic and neurodegenerative diseases. While ongoing research is investigating novel anti-inflammatory and immunomodulatory therapies for such conditions, available antirheumatic drugs may serve a similar purpose. One such drug, methotrexate, has been successfully used at high doses since the 1940s as an anticancer agent and, more recently, at lower doses in patients with autoimmune diseases. Although the effects of methotrexate have traditionally been attributed to its antiproliferative activity via folic acid modulation, additional targets have been identified, including AMP-activated protein kinase, Janus kinase/signal transducer and activator of transcription, high mobility group box 1 protein, the gut microbiota, and additional pharmacological effects of adenosine, a key mediator of methotrexate. The beneficial effects of modulating these targets on downstream inflammatory and immune pathways, cellular senescence, and vascular, metabolic, and brain homeostasis have been increasingly investigated in experimental models. Furthermore, studies conducted over the past 20 years suggest an association between low-dose methotrexate and a decreased risk of certain age-related cardiometabolic and neurodegenerative diseases, particularly in patients with autoimmune conditions. The results of these studies support the potential protective role of methotrexate against age-associated cardiometabolic and neurodegenerative diseases through multiple mechanisms, unlike targeted immunomodulatory and anti-inflammatory drugs, thereby providing a robust framework for investigating its repurposing in future intervention studies. SIGNIFICANCE STATEMENT: New treatments are essential to address the burden of age-related diseases. The important roles of dysregulated inflammation, immunity, and redox signaling in these conditions have spurred research into developing new therapies or repurposing existing drugs to target these dysfunctions. The disease-modifying antirheumatic drug methotrexate has shown potential protective effects against cellular senescence and certain age-related cardiometabolic and neurodegenerative diseases. This knowledge will encourage further research into the repurposing of methotrexate for the treatment of these diseases.

G-quadruplexes (G4s), a specialized nucleic acid secondary structure, have been found in recent years to be widely distributed in gene promoter regions. Growing evidence has highlighted the significance of G4 structures of promoter region in regulating various biological processes, including transcription and epigenetic regulation. In this review, we first proposed the 8 main characteristics of G-quadruplexes in the promoter region: widespread distribution, positional specificity, structural diversity, precise regulation, genetic modifiability, dynamic reversibility, signal responsiveness, and synergistic regulation. Common G4 regulators were then categorized as natural products, transcription factors and other binding proteins, small molecule ligands, and nucleic acids, which were fully summarized. Then different types of characterization methods for promoter region G4 and its ligands are summarized. Finally, the directions of promoter region G4 applications, including disease diagnosis, bioimaging, synthetic biology, targeted therapies, and antiviral potentials, which have been the focus of recent studies, are sorted out and presented. SIGNIFICANCE STATEMENT: Promoter G-quadruplexes (G4s) are emerging as dynamic and multifunctional regulatory elements that shape transcription, epigenetic states, and cellular responses to environmental cues. By pioneering the definition of 8 key features and corresponding regulatory mechanisms, this review highlights their significant potential as novel targets for therapeutic intervention and provides a comprehensive framework that advances both fundamental understanding and translational exploration of promoter G4s in disease diagnosis, imaging, synthetic biology, and targeted therapy.

Ovarian cancer (OC) is associated with high mortality and frequent resistance to poly (ADP-ribose) polymerase inhibitors, such as Olaparib, particularly in patients with breast cancer gene-proficient tumors. To explore the potential mechanisms underlying Olaparib resistance, Olaparib-resistant OC cell lines were established through stepwise drug induction. Candidate resistance-related genes were screened using bioinformatic analyses and subsequently validated in clinical specimens. Their biological functions and underlying mechanisms were further investigated through gene silencing, coimmunoprecipitation, immunofluorescence, comet assays, and an OVCAR3 xenograft model. Bioinformatic analyses indicated that thyroid hormone receptor interactor 13 (TRIP13) and kinetochore-associated 1 (KNTC1) were highly expressed in Olaparib-resistant cells and were associated with poor prognosis. Their elevated expression was further confirmed by real-time quantitative polymerase chain reaction, Western blotting, and immunohistochemistry. Functional studies showed that silencing either TRIP13 or KNTC1 inhibited cell proliferation and induced apoptosis in Olaparib-resistant OC cells. Mechanistically, coimmunoprecipitation and immunofluorescence analyses confirmed a cytoplasmic interaction between TRIP13 and KNTC1. TRIP13 knockdown impaired nonhomologous end joining (NHEJ)-mediated DNA repair, as evidenced by decreased expression of NHEJ-related proteins, increased γH2AX accumulation, and enhanced comet tail formation. Conversely, TRIP13 overexpression promoted NHEJ repair and reduced Olaparib-induced DNA damage, whereas these effects were partially reversed by the NHEJ inhibitor SCR130. In vivo, TRIP13 overexpression promoted tumor growth and reduced sensitivity to Olaparib, whereas KNTC1 knockdown reversed these effects. Collectively, these findings suggest that TRIP13 and KNTC1 cooperatively promote NHEJ-mediated DNA repair, thereby contributing to Olaparib resistance in breast cancer gene-proficient OC. Targeting the TRIP13/KNTC1 axis may therefore enhance the therapeutic efficacy of Olaparib and provide a promising strategy for overcoming poly (ADP-ribose) polymerase inhibitor resistance. SIGNIFICANCE STATEMENT: Olaparib resistance remains a major obstacle to effective ovarian cancer treatment. This study demonstrates that the thyroid hormone receptor interactor 13/kinetochore-associated 1 axis promotes Olaparib resistance in ovarian cancer by enhancing nonhomologous end joining-mediated DNA damage repair. Targeting this axis restored Olaparib sensitivity in resistant cells, thereby highlighting thyroid hormone receptor interactor 13/kinetochore-associated 1 as a potential therapeutic target for improving the response to poly (ADP-ribose) polymerase inhibitors.