Tumor cellular senescence, characterized by reversible cell cycle arrest following anti-cancer therapies, presents a complex paradigm in oncology. Given that senescent tumor cells may promote angiogenesis, tumorigenesis, and metastasis, selective killing senescent cells (SCs)-a strategy termed senotherapy-has emerged as a promising approach to improve cancer treatment. However, the clinical implementation of senotherapy faces significant hurdles, including lack of precise methods for SCs identification and the potential for adverse effects associated with highly cytotoxic senolytic agents. In this account, we elucidate recent advancement in developing novel approaches for the detection and selective elimination of SCs, encompassing prodrugs, nanoparticles, and other cutting-edge drug delivery systems such as PROTAC technology and CAR T cell therapy. Furthermore, we explore the paradoxical nature of SCs, which can induce growth arrest in adjacent neoplastic cells and recruit immunomodulatory cells that contribute to tumor suppression. Therefore, we utilize SCs membrane as vehicles to elicit antitumor immunity and potentially augment existing anti-cancer therapies. Finally, the opportunities and challenges are put forward to facilitate the development and clinical transformation of SCs detection, elimination or utilization.

Krukenberg tumors are a notably rare type of metastatic ovarian malignant tumor, often originating from the stomach. Due to their low incidence rate and the short survival time of patients, there is currently a lack of consensus on the diagnosis and treatment of this disease, as well as a deficiency in genomic analyses and research into the pathogenetic molecular mechanisms. In the present study, the case of a patient with gastric cancer who, 2 years after curative surgery and chemotherapy with oxaliplatin and tegafur, developed recurrent metastatic bilateral Krukenberg tumors with distant metastasis in the ovaries. During treatment, a total hysterectomy and bilateral salpingo-oophorectomy were performed, and intraoperative intraperitoneal chemotherapy with cisplatin (70 mg) was administered. Additionally, ureteroscopy and bilateral ureteral stent placement were conducted transurethrally. Post-surgery, assessments of the genomic alterations and microsatellite instability of the tumor revealed an AT-rich interaction domain 1A (ARID1A) exon c.4720delC mutation and a KRAS exon c.35G>C mutation. The potential pathogenic mechanisms and clinical significance of these mutations were then further discussed. Mutations in the ARID1A gene could increase the sensitivity of the patient to immune checkpoint inhibitor therapy. Additionally, the successful application of KRASG12C inhibitors in other cancer types offers a new approach for the targeted therapy of Krukenberg tumors. Therefore, the present study provides further evidence regarding the genomics of Krukenberg tumors, which may aid in the development of targeted treatment strategies.

During cytokinesis in human cells, a failure to resolve persistent DNA bridges that span the cell-division plane maintains the Aurora B-dependent abscission checkpoint in an active state. However, the molecular mechanism by which unresolved sister-chromatid bridging signals to this checkpoint is poorly defined. Here, we define an essential role for the Bloom's syndrome helicase, BLM, in signaling to the abscission-checkpoint machinery in response to replication stress through the conversion of dsDNA bridges into RPA-coated ssDNA. RPA then promotes ATR-CHK1 signaling to Aurora B, utilizing a kinase cascade shared with the S-phase checkpoint. BLM-deficient cells ultimately abandon cytokinesis in response to replication stress, which promotes binucleation and hence aneuploidy. Considering that aneuploidy is a hallmark of cancer, we propose that this role for BLM in cytokinesis is a plausible reason for cancer predisposition in Bloom's syndrome individuals. Consistent with this, BLM deficiency promotes anchorage-independent growth of non-cancer cells.

Homologous recombination repair (HRR) is crucial for maintaining genomic stability by repairing DNA damage. Despite its importance, HRR's role in cancer progression is not fully elucidated. Here, this work shows that nuclear-localized branched-chain α-ketoacid dehydrogenase kinase (BCKDK) acts as a modulator of HRR, promoting cell resistance against DNA damage-inducing therapy in breast cancer. Mechanistically, this work demonstrates that BCKDK is localized in the nucleus and phosphorylates RNF8 at Ser157, preventing the ubiquitin-mediated degradation of RAD51, thereby facilitating HRR-mediated DNA repair under replication stress. Notably, aberrant expression of the BCKDK/p-RNF8/RAD51 axis correlates with breast cancer progression and poor patient survival. Furthermore, this work identifies a small molecule inhibitor of BCKDK, GSK180736A, that disrupts its HRR function and exhibits strong tumor suppression when combined with DNA damage-inducing drugs. Collectively, this study reveals a new role of BCKDK in regulating HRR, independent of its metabolic function, presenting it as a potential therapeutic target and predictive biomarker in breast cancer.

External beam radiation therapy (RT) is a cornerstone of modern cancer management, being utilized in both curative and palliative settings due to its safety, efficacy, and widespread availability. A primary biological effect of RT is DNA damage, which leads to significant cytostatic and cytotoxic effects. Importantly, malignant cells possess a limited capacity for DNA repair compared to normal cells, and when combined with irradiation techniques that minimize damage to healthy tissues, this creates an advantageous therapeutic window. However, the clinical effectiveness of RT also appears to involve both direct and indirect interactions between RT and non-transformed components of the tumoral ecosystem, particularly immune cells. In this review, we describe the molecular and cellular mechanisms by which irradiated cancer cells modify the immunological tumor microenvironment and how such changes ultimately impact tumor growth.

Insufficient tumor cell-intrinsic interferon response represents a major obstacle in immune checkpoint blockade (ICB) therapy, particularly in anti-PD-1 treatment. Although cholesterol metabolism has been demonstrated to be a critical regulator of anti-tumor immune responses, whether cholesterol influences tumor cell-intrinsic interferon response in microsatellite instability (MSI) colorectal cancer (CRC) remains unknown. Through comprehensive siRNA library screening and Gene Set Enrichment Analysis (GSEA), we identified mevalonate kinase (MVK) as a crucial negative regulator of tumor cell-intrinsic interferon response in MSI CRC cells. Genetic ablation of MVK resulted in significant upregulation of Th1 type chemokines (CXCL9 and CXCL10) and enhanced CD8+T cell infiltration in MSI CRC, consequently leading to marked tumor growth suppression in immunocompetent mice. At the molecular level, we demonstrated that MVK physically interacts with the transcriptional activation domain (TAD) of signal transducer and activator of transcription 1 (STAT1). This interaction substantially impairs STAT1 nuclear translocation, thereby attenuating interferon signaling cascade. Furthermore, analyses of humanized PBMC-PDX models and clinical cohorts of MSI CRC patients revealed that reduced MVK expression in tumor tissues strongly correlates with favorable responses to anti-PD-1 therapy. Collectively, our findings establish MVK as a pivotal mediator in cholesterol synthesis pathway that negatively regulates tumor cell-intrinsic interferon response in MSI CRC. These results suggest that therapeutic targeting of MVK represents a promising strategy to enhance ICB efficacy through potentiation of interferon responses in MSI CRC patients.

Tumorigenesis in mammals is driven by inherited genetic variants, environmental factors and random errors during normal DNA replication that lead to cancer-causing mutations. These factors initiate uncontrolled cellular proliferation and disrupt the regulation of critical checkpoints. A few mammalian species possess unique protective mechanisms that enable them to resist widespread cancer development and achieve longevity. Tissue-specific tumor protection adds another layer of complexity to this diversity. Breast cancer is a leading cause of human mortality, particularly among females. Driven by the need for new strategies in treatment and prevention, this opinion article explores and supports the idea that herbivores are more resistant to mammary cancer than carnivores and omnivores. This diversity has occurred despite the remarkably similar basic mammary biology. Herbivores' meatless diet cannot explain the differences in cancer resistance, which have accompanied species segregation since the Jurassic era. To investigate the causes of this diversity, the characteristics of tumorigenesis in the human breast-and to a lesser extent in other carnivores-have been compared with data from retrospective analyses of bovine mammary tumor development across various locations over the past century. Well-established genomic, cellular, and systemic triggers of breast cancer exhibit different, or less pronounced tissue-specific activity in the bovine mammary gland, accompanied by novel bovine-specific protective mechanisms. Together, these factors contribute to the near absence of breast cancer in bovines and offer a basis for developing future anticancer strategies.

The intricate relationship between cancer, circadian rhythms, and aging is increasingly recognized as a critical factor in understanding the mechanisms underlying tumorigenesis and cancer progression. Aging is a well-established primary risk factor for cancer, while disruptions in circadian rhythms are intricately associated with the tumorigenesis and progression of various tumors. Moreover, aging itself disrupts circadian rhythms, leading to physiological changes that may accelerate cancer development. Despite these connections, the specific interplay between these processes and their collective impact on cancer remains inadequately explored in the literature. In this review, we systematically explore the physiological mechanisms of circadian rhythms and their influence on cancer development. We discuss how core circadian genes impact tumor risk and prognosis, highlighting the shared hallmarks of cancer and aging such as genomic instability, cellular senescence, and chronic inflammation. Furthermore, we examine the interplay between circadian rhythms and aging, focusing on how this crosstalk contributes to tumorigenesis, tumor proliferation, and apoptosis, as well as the impact on cellular metabolism and genomic stability. By elucidating the common pathways linking aging, circadian rhythms, and cancer, this review provides new insights into the pathophysiology of cancer and identifies potential therapeutic strategies. We propose that targeting the circadian regulation of cancer hallmarks could pave the way for novel treatments, including chronotherapy and antiaging interventions, which may offer important benefits in the clinical management of cancer.

Triple-negative breast cancer (TNBC) could benefit from PARP inhibitors (PARPi) for their frequent defective homologous recombination repair (HR). However, the efficacy of PARPi is limited by their lower bioavailability and high susceptibility to drug resistance, so it often needs to be combined with other treatments. Herein, polydopamine nanoparticles (PDMN) were constructed to load Olaparib (AZD) as two-channel therapeutic nanoplatforms. The PDMN has a homogeneous spherical structure around 100 nm and exhibits a good photothermal conversion efficiency of 62.4%. The obtained AZD-loaded nanoplatform (PDMN-AZD) showed enhanced antitumor effects through the combination of photothermal therapy (PTT) and PARPi. By western blot and flow cytometry, we found that PTT and PARPi could exert synergistic antitumor effects by further increasing DNA double-strand damage (DSBs) and enhancing HR defects. The strongest therapeutic effect of PDMN-AZD was observed in a BRCA-deficient mouse tumor model. In conclusion, the PDMN-AZD nanoplatform designed in this study demonstrated the effectiveness of PTT and PARPi for synergistic treatment of TNBC and preliminarily explained the mechanism.

Protein kinase dysregulation is a hallmark of many cancers, yet their tumorigenic mechanisms remain elusive despite 60 years of study. Since learning that their mechanism includes catalyzing phosphorylation of amino acids in protein substrates, researchers began devising their inhibition strategies. Initially, protein kinase inhibitors (PKIs) derived from natural products were employed despite high cytotoxicity risks. While synthetic PKIs proved less toxic, they face significant drug resistance challenges. This review examines the progress in understanding protein kinases' role in cancer, their classification and modes of action since their discovery. To illuminate the path towards less toxic yet highly effective kinase inhibitors, this study analyzes the synthesis and modification of all FDA-approved natural product derived kinase inhibitors (NPDKIs) as well as those that failed clinical trials. By providing insights into successful and unsuccessful approaches, this review also aims to advance medicinal chemistry strategies for developing more effective and safer PKIs, potentially improving cancer treatment outcomes.

Radioresistance remains a major obstacle in cervical cancer treatment, frequently engendering tumor relapse and metastasis. However, the details of its mechanism of action remain largely enigmatic. This study delineates the prospective impacts of short-form human T-cell lymphoma invasion and metastasis 2 (TIAM2S) involving the radiation resistance of cervical cancer. In this study, we established three pairs of radioresistant (RR) cervical cancer cells (HeLa, C33A and CaSki) and their parental wild-type (WT) cells. We revealed a consistent augmentation of TIAM2S, but not long-form human T-cell lymphoma invasion and metastasis 2 (TIAM2L) were displayed in RR cells that underwent a 6 Gy radiation administration. Remarkably, RR cells exhibited decreased radiosensitivity and abridged apoptosis, as estimated through a clonogenic survival curve assay and Annexin V/Propidium Iodide apoptosis assay, respectively. TIAM2S suppression increased radiosensitivity and enhanced cell apoptosis in RR cells, whereas its forced introduction modestly abolished radiosensitivity and diminished WT cell apoptosis. Furthermore, TIAM2S overexpression notably aggravated RR cell migration, whereas its blockage reduced WT cell mobilities, as confirmed by an in vitro time-lapse recording assay. Notably, augmented lung localization was revealed after a tail-vein injection of CaSki-RR cells using the in vivo short-term lung locomotion BALB/c nude mouse model. TIAM2S impediment notably reduced radioresistance-increased lung locomotion. This study provides evidence that TIAM2S may operate as an innovative signature in cervical cancer that is resistant to radiotherapy. It displays multi-faceted roles including radioprotection, restricting apoptosis, promoting cell proliferation, and escalating cell migration/metastasis. Targeting TIAM2S, together with conventional radiotherapy, may be an innovative strategy for intensifying radiosensitivity and protecting against subsequent uncontrolled tumor growth and metastasis in cervical cancer treatment.

Barrett's esophagus (BE) is described by the transformation of the normal squamous epithelium into metaplastic columnar epithelium, driven by chronic gastroesophageal reflux disease (GERD). BE is a recognized premalignant condition and the main precursor to esophageal adenocarcinoma (EAC). Understanding the molecular mechanisms underlying BE carcinogenesis is crucial for improving prevention, surveillance, and treatment strategies.

This narrative review examines the molecular abnormalities associated with the progression of BE to EAC.

This study highlights inflammatory, genetic, epigenetic, and chromosomal alterations, emphasizing key pathways and biomarkers. BE progression follows a multistep process involving dysplasia and genetic alterations such as TP53 and CDKN2A (p16) mutations, chromosomal instability, and dysregulation of pathways like PI3K/AKT/mTOR. Epigenetic alterations, including aberrant microRNA expression or DNA methylation, further contribute to this progression. These molecular changes are stage-specific, with some alterations occurring early in BE during the transition to high-grade dysplasia or EAC. Innovations in chemoprevention, such as combining proton pump inhibitors and aspirin, and the potential of antireflux surgery to halt disease progression are promising. Incorporating molecular biomarkers into surveillance strategies and advancing precision medicine may enable earlier detection and personalized treatments.

BE is the primary preneoplastic condition for EAC. A deeper understanding of its molecular transformation can enhance surveillance protocols, optimize the management of gastroesophageal reflux inflammation, and refine prevention and therapeutic strategies, ultimately contributing to a reduction in the global burden of EAC.

Mutation in genes involved in DNA replication continuously disrupt DNA replication and give rise to genomic instability, a critical driver of oncogenesis. To prevent leukemia, immature T lymphocytes with genomic instability often undergo rapid cell death during development. However, the mechanism by which immature T lymphocytes undergo rapid cell death upon genomic instability has been enigmatic. Here we show that zebrafish mcm5 mutation leads to DNA damage in immature T lymphocytes and the immature T cells sensitively undergo rapid cell death. Detailed analyses demonstrated that the immature T lymphocytes undergo rapid apoptosis via upregulation of tp53 and downregulation of bcl2 transcription in mcm5 mutants. Mechanistically, Mcm5 directly binds to Stat1a and facilitates its phosphorylation to enhance bcl2a expression under the conditions of DNA replication stress. However, in mcm5 mutants, the absence of the Mcm5-Stat1 complex decreases Stat1 phosphorylation and subsequent bcl2a transcription, accelerating apoptosis of immature T lymphocytes with genomic instability. Furthermore, our study shows that the role of Mcm5 in T-cell development is conserved in mice. In conclusion, our work identifies a role of Mcm5 in regulating T cell development via Stat1-Bcl2 cascade besides its role in DNA replication, providing a kind of mechanism by which immature T cells with gene mutation-induced DNA damage are rapidly cleared during T lymphocyte development.

Cancer cells display high levels of oncogene-induced replication stress (RS) and rely on DNA damage checkpoint for viability. This feature is exploited by cancer therapies to either increase RS to unbearable levels or inhibit checkpoint kinases involved in the DNA damage response. Thus far, treatments that combine these two strategies have shown promise but also have severe adverse effects. To identify novel, better-tolerated anticancer combinations, we screened a collection of plant extracts and found two natural compounds from the plant, Psoralea corylifolia, that synergistically inhibit cancer cell proliferation. Bakuchiol inhibited DNA replication and activated the checkpoint kinase CHK1 by targeting DNA polymerases. Isobavachalcone interfered with DNA double-strand break repair by inhibiting the checkpoint kinase CHK2 and DNA end resection. The combination of bakuchiol and isobavachalcone synergistically inhibited cancer cell proliferation in vitro. Importantly, it also prevented tumor development in xenografted NOD/SCID mice. The synergistic effect of inhibiting DNA replication and CHK2 signaling identifies a vulnerability of cancer cells that might be exploited by using clinically approved inhibitors in novel combination therapies.

Breast cancer is among the most prevalent malignant tumors globally, with carboplatin serving as a standard treatment option. However, resistance often compromises its efficacy. DNA damage repair (DDR) pathways are crucial in determining responses to treatment and are also associated with immune infiltration. This study aimed to identify the DDR genes involved in carboplatin resistance and to elucidate their effects on prognosis, immune infiltration, and drug sensitivity in breast cancer patients.

A 3D-culture model resistant to carboplatin was constructed and sequenced. Co-expressed DDR genes were analyzed to develop a predictive model. Immune infiltration analysis tools were employed to assess the immune microenvironment of patients with varying expression levels of these risk genes. Additionally, drug sensitivity predictions were made to evaluate the efficacy of other DNA damage-related drugs across different risk groups. Molecular assays were performed to investigate the role of the key gene TONSL in breast cancer.

By integrating data from public database, we established a prognostic signature comprising thirteen DDR genes. Our analysis indicated that this model is associated with immune infiltration patterns in breast cancer patients, particularly concerning CD8+ T cells and NK cells. Additionally, it demonstrated a significant correlation with sensitivity to other DDR-related drugs, suggesting its potential as a biomarker for treatment efficacy. Compared to the control group, TONSL-knockdown cell lines exhibited a diminished response to DNA-damaging agents, marked by a notable increase in DNA damage levels and enhanced drug sensitivity. Furthermore, single-cell analysis revealed elevated TONSL expression in dendritic and epithelial cells, particularly in triple-negative breast cancers.

Carboplatin resistance-related DDR genes are associated with prognosis, immune infiltration, and drug sensitivity in breast cancer patients. TONSL may serve as a potential therapeutic target for breast cancer, particularly in triple-negative breast cancer, indicating new treatment strategies for these patients.

An ideal chemotherapeutic agent damages DNA, specifically in cancer cells, without harming normal cells. Recently, we used Box A of HMGB1 plasmid as molecular scissors to produce DNA gaps in normal cells. The DNA gap relieves DNA tension and increases DNA strength, preventing DNA double-strand breaks (DSBs). Since the formation of HMGB1-produced DNA gaps in cancers may differ from normal cells, the outcome of introducing Box A into cancer cells may be different. We demonstrated that in lung cancer cells, γH2AX foci and histone modification associating DSBs were produced by Box A. We transfected Box A plasmid into lung cancer cell lines to overexpress Box A and evaluated the expression levels of γH2AX foci and other DNA damage response (DDR) signaling cascade markers, including ATM, ATR, and p53. Then, we demonstrated the downstream effects of DSBs on lung cancer, lowering cell proliferation, decreasing cell migration, and promoting apoptosis. Thus, Box A in lung cancer promoted the opposite outcome to normal cells by breaking cancer DNA.

Long AT repeat tracts form non-B DNA structures that stall DNA replication and cause chromosomal breakage. AT repeats are abundant in human common fragile sites (CFSs), genomic regions that undergo breakage under replication stress. Using an in vivo yeast model system containing AT-rich repetitive elements from human CFS FRA16D, we find that DNA polymerase zeta (Pol ζ) is required to prevent breakage and subsequent deletions at hairpin and cruciform forming (AT/TA)n sequences, with little to no role at an (A/T)28 repeat or a control non-structure forming sequence. DNA polymerase eta is not protective for deletions at AT-rich structures, while DNA polymerase delta is protective, but not in a repeat-specific manner. Using purified replicative holoenzymes in vitro, we show that hairpin structures are most inhibitory to yeast DNA polymerase epsilon, whereas yeast and human Pol ζ efficiently synthesize these regions in a stepwise manner. A requirement for the Rev1 protein and the modifiable lysine 164 of proliferating cell nuclear antigen to prevent deletions at AT/TA repeats suggests a mechanism for Pol ζ recruitment. Our results reveal a novel role for Pol ζ in replicating through AT-rich hairpins and suggest a role for Pol ζ in rescue of stalled replication forks caused by DNA structures.

A series of novel isatin-oxime ether derivatives were designed, synthesized and characterized by 1H NMR and 13C NMR and HRMS. These compounds were evaluated for their in vitro cytotoxicity against three human cancer cell lines (A549, HepG2 and Hela) by MTT assay. According to the experimental results, compounds 6a (IC50 = 0.34μM), 6c (IC50 = 14nM) and 6r (IC50 = 45nM) were found as the excellent selectivity and high activity against A549, whereas compounds 6m (IC50 = 12nM) and 6n (IC50 = 25nM) displayed the significant activity for HepG2, respectively. Compound 6f (IC50 = 30nM), 6n (IC50 = 9nM) and 6o (IC50 = 20nM) also showed the excellent activity against Hela. From the experiments of cell migration and colony formation assays, the findings demonstrated that 6m can effectively suppress the migration and growth of HepG2 cells. In addition, the results of molecular docking studies determined the strong binding interactions between the potential active compounds 6m and 6n and the active sites of isocitrate dehydrogenase 1 (IDH1) with the lowest binding affinity energy.

Tandem duplications (TD) are among the most frequent type of structural variant (SV) in the cancer genome. They are characterized by a single breakpoint junction that defines the boundaries and the size of the duplicated segment. Cancer-associated TDs often increase oncogene copy number or disrupt tumor suppressor gene function, and thus have important roles in tumor evolution. TDs in cancer genomes fall into three classes, defined by the size of duplications, and are associated with distinct genetic drivers. In this review, we survey key features of cancer-related TDs and consider possible underlying mechanisms in relation to stressed DNA replication and the 3D organization of the S phase genome.

Cellular senescence, a state of permanent cell cycle arrest, recapitulates the aging process at the cellular level. It can be triggered by intrinsic or extrinsic factors including telomere shortening (replicative senescence) and in response to various types of stresses such as oncogenic stress (oncogene-induced senescence, OIS). Senescence has been detected in vitro and in premalignant lesions in mice and humans expressing mutant oncogenes. MicroRNAs (miRNAs) are short noncoding RNAs that regulate gene expression at the posttranscriptional level, and have been involved in both replicative senescence and OIS. Several methods have been used to identify miRNAs and compare their expression in normal versus oncogene-induced senescent cells, as well as to analyze their role and their targets in senescence. Here, we describe several methods that can be employed to identify miRNAs in cells undergoing OIS, including miRNA-sequencing, RT-qPCR-based detection and quantification of miRNAs and Nanostring miRNA analysis (nCounter miRNA Expression Assay). Moreover, we perform a meta-analysis of studies employing the above methodologies, pinpoint miRNAs with consistent expression changes across senescence models, and predict their target genes and the pathways in which they partake.

Senescence is an inherent cellular mechanism triggered as a response to stressful insults. It associates with several aspects of cancer progression and therapy. Senescent cells constitute a highly heterogeneous cellular population and their identification can be very challenging. In fact, the term "senescence" has been often misused. This is also true in the case of immune cells. While several studies indicate the presence of senescent-like features (mainly in T cells), senescent immune cells are poorly described. Under this prism, we herein review the current literature on what has been characterized as T cell senescence and provide insights on how to accurately discriminate senescent cells against exhausted or anergic ones. We also summarize the major metabolic and epigenetic modifications associated with T cell senescence and underline the role of senescent T cells in the tumor microenvironment (TME). Moreover, we discuss how these cells associate with standard clinical therapeutic interventions and how they impact their efficacy. Finally, we underline the importance of precise identification and thorough characterization of "truly" senescent T cells in order to design successful therapeutic manipulations that would delay cancer incidence and maximize efficacy of immunotherapy.

The emerging field of senolytics is centered on eliminating senescent cells to block their contribution to the progression of age-related diseases, including cancer, and to facilitate healthy aging. Enhancing the selectivity of senolytic treatments toward senescent cells stands to reduce the adverse effects associated with existing senolytic interventions. Taking advantage of lipofuscin accumulation in senescent cells, we describe here the development of a highly efficient senolytic platform consisting of a lipofuscin-binding domain scaffold, which can be conjugated with a senolytic drug via an ester bond. As a proof of concept, we present the generation of GL392, a senolytic compound that carries a dasatinib senolytic moiety. Encapsulation of the GL392 compound in a micelle nanocarrier (termed mGL392) allows for both in vitro and in vivo (in mice) selective elimination of senescent cells via targeted release of the senolytic agent with minimal systemic toxicity. Our findings suggest that this platform could be used to enhance targeting of senotherapeutics toward senescent cells.

DNA double-strand breaks (DSBs) are a major source of genomic instability. Physiological DSBs are naturally occurring breaks that happen during normal cellular processes. Unlike DNA breaks resulting from DNA damage due to external factors like radiation or chemicals, physiological DSBs play critical roles in various normal biological functions. Some key processes involving physiological DSBs include V(D)J recombination, transcription, and replication. These breaks are typically tightly controlled and are part of the cellular machinery designed to maintain and enhance genomic integrity and diversity. However, if these breaks are misrepaired or left unrepaired, they can contribute to genomic instability, potentially leading to senescence and diseases such as cancer. Here, we outline various methods commonly employed to detect physiological DSBs and introduce a detailed, step-by-step protocol for mapping these breaks using the in-suspension break labeling in situ and sequencing (sBLISS) technique. sBLISS offers single nucleotide resolution and is versatile enough to be applied to any cell type amenable to single-cell suspension. This comprehensive approach not only enhances our understanding of DSBs but also aids in the exploration of their roles in genomic instability.

Low-grade glioma (LGG) is a slow-growing but invasive tumor that affects brain function. Histone deacetylases (HDACs) play a critical role in gene regulation and tumor progression. This study aims to develop a prognostic model based on HDAC-related genes to aid in risk stratification and predict therapeutic responses.

Expression data from The Cancer Genome Atlas (TCGA) and Chinese Glioma Genome Atlas (CGGA) were analyzed to identify an optimal HDAC-related risk signature from 73 genes using 10 machine learning algorithms. Patients were stratified into high- and low-risk groups based on the median risk score. Prognostic accuracy was evaluated using Kaplan-Meier survival analysis and receiver operating characteristic (ROC) curves. Functional enrichment analyses, including Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Gene Set Enrichment Analysis (GSEA), were performed to explore pathways linked to the gene signature. Immune infiltration and tumor microenvironment characteristics were assessed using Single Sample Gene Set Enrichment Analysis (ssGSEA) and ESTIMATE algorithm. SubMap was applied to predict responsiveness to immune checkpoint inhibitors, and chemotherapeutic sensitivity was analyzed via the Genomics of Drug Sensitivity in Cancer (GDSC) database.

A prognostic model consisting of four HDAC-related genes-SP140, BAZ1B, SP100, and SIRT1-was identified. This signature displayed strong prognostic accuracy, achieving a C-index of 0.945. Individuals with LGG were systematically divided into high-risk and low-risk cohorts based on the median risk value, enabling more precise risk stratification. The survival prognosis was significantly worse in the high-risk cohort compared to the low-risk group, highlighting distinct survival trajectories. Notably, the two cohorts exhibited marked shifts in immune checkpoint gene transcriptional profiles and immune cell infiltration maps, underscoring fundamental biological differences that contribute to these differing prognoses.

We developed an HDAC-related four-gene prognostic model that correlates with survival, immune landscape, and therapeutic response in LGG patients. This model may guide personalized treatment strategies and improve prognostic accuracy, warranting further validation in clinical settings.

DNA double-strand breaks (DSBs) occurring within the genomic DNA of mammalian cells significantly impact cell survival, depending upon their repair capacity. This study presents a mathematical model to fit fibroblast survival rates with a sequence-specific DSB burden induced by the restriction enzyme AsiSI. When cells had a sporadic DSB burden under mixed culture, cell growth showed a good fit to the Lotka-Volterra competitive equation, predicting the presence of modifying factors acting as competitive cell-to-cell interactions compared to monocultures. Under the predicted condition, we found the Acta2 gene, a known marker of cancer-associated fibroblasts, played a role in competitive interactions between cells with different DSB burdens. These data suggest that the progression to the cancer microenvironment is determined by genomic stress, providing clues for estimating cancer risk by reconsidering the fitness of cells in their microenvironment.

Cell division cycle 6 (CDC6) is essential for the initiation of DNA replication in eukaryotic cells and contributes to the development of various human tumors. Polycystic ovarian syndrome (PCOS) is a reproductive endocrine disease in women of childbearing age, with a significant risk of endometrial cancer (EC). However, the role of CDC6 in the progression of PCOS to EC is unclear. Therefore, we examined CDC6 expression in patients with PCOS and EC. We evaluated the relationship between CDC6 expression and its prognostic value, potential biological functions, and immune infiltrates in patients with EC. In vitro analyses were performed to investigate the effects of CDC6 knockdown on EC proliferation, migration, invasion, and apoptosis. CDC6 expression was significantly upregulated in patients with PCOS and EC. Moreover, this protein caused EC by promoting the aberrant infiltration of macrophages into the immune microenvironment in patients with PCOS. A functional enrichment analysis revealed that CDC6 exerted its pro-cancer and pro-immune cell infiltration functions via the PI3K-AKT pathway. Moreover, it promoted EC proliferation, migration, and invasion but inhibited apoptosis. This protein significantly reduced EC survival when mutated. These findings demonstrate that CDC6 regulates the progression of PCOS to EC and promotes immune infiltration.

Epithelial-to-mesenchymal transition (EMT) allows cancer cells to metastasize while acquiring resistance to apoptosis and chemotherapeutic agents with significant implications for patients' prognosis and survival. Despite its clinical relevance, the mechanisms initiating EMT during cancer progression remain poorly understood. We demonstrate that DNA damage triggers EMT and that activation of poly (ADP-ribose) polymerase (PARP) and the PARP-dependent chromatin remodeler ALC1 (CHD1L) was required for this response. Our results suggest that this activation directly facilitates access to the chromatin of EMT transcriptional factors (TFs) which then initiate cell reprogramming. We also show that EMT-TFs bind to the RAD51 promoter to stimulate its expression and to promote DNA repair by homologous recombination. Importantly, a clinically relevant PARP inhibitor reversed or prevented EMT in response to DNA damage while resensitizing tumor cells to other genotoxic agents. Overall, our observations shed light on the intricate relationship between EMT, DNA damage response, and PARP inhibitors, providing potential insights for in cancer therapeutics.

The MRE11 complex (comprising MRE11, RAD50, and NBS1) is integral to the maintenance of genome stability. We previously showed that a hypomorphic Mre11 mutant mouse strain (Mre11 ATLD1/ATLD1 ) was highly susceptible to oncogene-induced breast cancer. Here we used a mammary organoid system to examine which MRE11-dependent responses are tumor-suppressive. We found that Mre11 ATLD1/ATLD1 organoids exhibited an elevated interferon-stimulated gene (ISG) signature and sustained changes in chromatin accessibility. This Mre11 ATLD1/ATLD1 phenotype depended on DNA binding of a nuclear innate immune sensor, IFI205. Ablation of Ifi205 in Mre11 ATLD1/ATLD1 organoids restored baseline and oncogene-induced chromatin accessibility patterns to those observed in WT. Implantation of Mre11 ATLD1/ATLD1 organoids and activation of the oncogene led to aggressive metastatic breast cancer. This outcome was reversed in implanted Ifi205 -/- Mre11 ATLD1/ATLD1 organoids. These data reveal a connection between innate immune signaling and tumor development in the mammary epithelium. Given the abundance of aberrant DNA structures that arise in the context of genome instability syndromes, the data further suggest that cancer predisposition in those contexts may be partially attributable to chronic innate immune transcriptional programs.

BRAF V600E, one of the most frequent mutations in the MAPK pathway, confers poor prognosis to colorectal cancers (CRCs), partly because of chemotherapeutic resistance. Oncogene-induced DNA damage responses (DDRs) that primarily activate p53 are important mechanistic barriers to the malignant transformation of cells; however, the mechanism underlying this impairment in cancer remains unknown. Here, we evaluated the responses of BRAFV600E-induced DDRs in two CRC cell lines, SW48 and LIM1215, both of which harbor wild-type TP53, KRAS, and BRAF. BRAFV600E transduction exhibited distinct phenotypes in these cells: SW48 cell proliferation markedly decreased, whereas that of LIM1215 increased. BRAFV600E expression induced the activation of oncogene-induced DDR signaling in SW48 cells, but not in LIM1215 cells, whereas chemotherapeutic agents similarly activated DDRs in both cell lines. Knockdown experiments revealed that these responses in SW48 cells were mediated by p53-p21 pathway activation. Comet assay (both alkaline and neutral) revealed that BRAFV600E increased single-strand breaks to the same extent in both cell lines; however, in the case of LIM1215 cells, it only facilitated double-strand breaks. Furthermore, the proliferation of LIM1215 cells, wherein no oncogene-induced DDRs occurred, was synergistically inhibited upon MDM2 inhibitor-mediated p53 activation combined with MEK inhibition. Taken together, these distinct DDR signaling responses highlight the novel characteristics of BRAFV600E-mutated CRC cells and define the therapeutic potential of p53 activation combined with MAPK inhibition against TP53 wild-type CRC harboring a BRAFV600E mutation.

While oncogenes promote cancer cell growth, unrestrained proliferation represents a significant stressor to cellular homeostasis networks such as the DNA damage response (DDR). To enable oncogene tolerance, many cancers disable tumor suppressive DDR signaling through genetic loss of DDR pathways and downstream effectors (e.g., ATM or p53 tumor suppressor mutations). Whether and how oncogenes can help "self-tolerize" by creating analogous functional defects in physiologic DDR networks is not known. Here we focus on Ewing sarcoma, a FET fusion oncoprotein (EWSR1-FLI1) driven pediatric bone tumor, as a model for the class of FET rearranged cancers. Native FET family members are among the earliest factors recruited to DNA double-strand breaks (DSBs), though the function of both native FET proteins and FET fusion oncoproteins in DNA repair remains to be defined. We discover that the EWSR1-FLI1 fusion oncoprotein is recruited to DNA DSBs and interferes with native FET (EWSR1) protein function in activating the DNA damage sensor ATM. In multiple FET rearranged cancers, FET fusion oncoproteins induce functional ATM defects, rendering the compensatory ATR signaling axis as a collateral dependency and therapeutic target. More generally, we find that aberrant recruitment of a fusion oncoprotein to sites of DNA damage can disrupt physiologic DSB repair, revealing a mechanism for how growth-promoting oncogenes can also create functional defects within tumor suppressive DDR networks.

Completion of DNA replication before chromosome segregation is essential for the stable maintenance of the genome. Under replication stress, DNA synthesis may persist beyond S phase, especially in genomic regions that are difficult to proceed with the replication processes. Incomplete replication in mitosis emerges as non-disjoined segment in mitotic chromosomes leading to anaphase bridges. The resulting chromosome rearrangements are not well characterized, however. Here, we report that incomplete replication due to SMC5/6 deficiency impairs sister chromatid disjunction at difficult-to-replicate regions, including common fragile sites. These non-disjoined regions manifest as cytologically defined symmetric gaps, causing anaphase bridges. These bridges break at the gaps, leading to telomere loss, micronucleation, and fragmentation. Subsequently, fusions between telomere-deficient chromosomes generate complex chromosomal rearrangements, including dicentric chromosomes, suggesting the occurrence of breakage-fusion-bridge cycle. Additionally, chromosomes in micronuclei were pulverized, indicative of chromothripsis. Our findings suggest that incomplete replication facilitates complex chromosomal rearrangements, which may contribute to genomic instability in human cancers.

Chemotherapy is a therapy of choice for many cancers. However, it is often inefficient for long-term patient survival and is usually accompanied by multiple adverse effects. The adverse effects are mainly associated with toxicity to normal cells, frequently resulting in immune system depression, nausea, loss of appetite and metabolic changes. In this respect, the combination of chemotherapy with cannabinoids, especially non-psychoactive, such as cannabidiol, cannabinol and other minor cannabinoids, as well as terpenes, may become very useful. This is especially pertinent because the mechanisms of anticancer effects of cannabinoids on cancer cells are often different from conventional chemotherapeutics. In addition, cannabinoids help alleviate chemotherapy-induced adverse effects, regulate sleep and appetite, and are shown to have analgesic properties. Another component for achieving potential anti-cancer synergism is regulating nutrient availability and metabolism by calorie restriction and intermittent fasting in cancer cells. As tumours require a lot of energy to grow and because glucose is constantly available, malignant cells often opt to use glucose as a primary source of ATP production through substrate-level phosphorylation (fermentation) rather than through oxidative phosphorylation. Thus, periodic depletion of cancer cells of primary fuel, glucose, could result in a strong synergy in killing cancer cells by chemo- and possibly radiotherapy when combined with cannabinoids. This commentary will discuss what is known about such combinatorial treatments, including potential mechanisms and future protocols.

The DNA damage response (DDR) pathway is a cardinal cellular stress response mechanism that during cancer development follows an antagonistic pleiotropy mode of action. Given that DDR activation is an energy demanding process, interplay with macroautophagy/autophagy, a stress response and energy providing mechanism, is likely to take place. While molecular connections between both mechanisms have been reported, an open question regards whether autophagy activation follows solely or is entangled with DDR in a similar antagonistic pleiotropy pattern during cancer development. Combing evidence on the spatiotemporal relationship of DDR and autophagy in the entire spectrum of carcinogenesis from our previous studies, we discuss these issues in the current addendum.Abbreviation: AMPK: AMP-dependent protein kinase; DDR: DNA damage response.

Activation of oncogenes disturbs a wide variety of cellular processes and induces physiological dysregulation of DNA replication, widely referred to as replication stress (RS). Oncogene-induced RS can cause replication forks to stall or collapse, thereby leading to DNA damage. While the DNA damage response (DDR) can provoke an anti-tumor barrier to prevent the development of cancer, a small subset of cells triggers replication stress tolerance (RST), allowing precancerous cells to survive, thereby promoting clonal expansion and genomic instability (GIN). Genomic instability (GIN) is a hallmark of cancer, driving genetic alterations ranging from nucleotide changes to aneuploidy. These alterations increase the probability of oncogenic events and create a heterogeneous cell population with an enhanced ability to evolve. This review explores how major oncogenes such as RAS, cyclin E, and MYC induce RS through diverse mechanisms. Additionally, we delve into the strategies employed by normal and cancer cells to tolerate RS and promote GIN. Understanding the intricate relationship between oncogene activation, RS, and GIN is crucial to better understand how cancer cells emerge and to develop potential cancer therapies that target these vulnerabilities.

PML, a multifunctional protein, is crucial for forming PML-nuclear bodies involved in stress responses. Under specific conditions, PML associates with nucleolar caps formed after RNA polymerase I (RNAPI) inhibition, leading to PML-nucleolar associations (PNAs). This study investigates PNAs-inducing stimuli by exposing cells to various genotoxic stresses. We found that the most potent inducers of PNAs introduced topological stress and inhibited RNAPI. Doxorubicin, the most effective compound, induced double-strand breaks (DSBs) in the rDNA locus. PNAs co-localized with damaged rDNA, segregating it from active nucleoli. Cleaving the rDNA locus with I-PpoI confirmed rDNA damage as a genuine stimulus for PNAs. Inhibition of ATM, ATR kinases, and RAD51 reduced I-PpoI-induced PNAs, highlighting the importance of ATM/ATR-dependent nucleolar cap formation and homologous recombination (HR) in their triggering. I-PpoI-induced PNAs co-localized with rDNA DSBs positive for RPA32-pS33 but deficient in RAD51, indicating resected DNA unable to complete HR repair. Our findings suggest that PNAs form in response to persistent rDNA damage within the nucleolar cap, highlighting the interplay between PML/PNAs and rDNA alterations due to topological stress, RNAPI inhibition, and rDNA DSBs destined for HR. Cells with persistent PNAs undergo senescence, suggesting PNAs help avoid rDNA instability, with implications for tumorigenesis and aging.

Epigenetic mechanisms often fuel the quick evolution of cancer cells from normal cells. Mutations or aberrant expressions in the enzymes of DNA methylation, histone post-translational modifications, and chromatin remodellers have been extensively investigated in cancer pathogenesis; however, cancer-associated histone mutants have gained momentum in recent decades. Next-generation sequencing of cancer cells has identified somatic recurrent mutations in all the histones (H3, H4, H2A, H2B, and H1) with different frequencies for various tumour types. Importantly, the well-characterised H3K27M, H3G34R/V, and H3K36M mutations are termed as oncohistone mutants because of their wide roles, from defects in cellular differentiation, transcriptional dysregulation, and perturbed epigenomic profiles to genomic instabilities. Mechanistically, these histone mutants impart their effects on histone modifications and/or on irregular distributions of chromatin complexes. Recent studies have identified the crucial roles of the H3K27M and H3G34R/V mutants in the DNA damage response pathway, but their impacts on chemotherapy and tumour progression remain elusive. In this review, we summarise the recent developments in their functions toward genomic instabilities and tumour progression. Finally, we discuss how such a mechanistic understanding can be harnessed toward the potential treatment of tumours harbouring the H3K27M, H3G34R/V, and H3K36M mutations.

Cytokinetic abscission is a crucial process that guides the separation of daughter cells at the end of each cell division. This process involves the cleavage of the intercellular bridge, which connects the newly formed daughter cells. Over the years, researchers have identified several cellular contributors and intracellular processes that influence the spatial and temporal distribution of the cytoskeleton during cytokinetic abscission. This review presents the most important scientific discoveries that allow activation of the abscission checkpoint, ensuring a smooth and successful separation of a single cell into two cells during cell division. Here, we describe different factors, such as abscission checkpoint, ICB tension, nuclear pore defects, DNA replication stress, chromosomal stability, and midbody proteins, which play a role in the regulation and correct timing of cytokinetic abscission. Furthermore, we explore the downsides associated with the dysregulation of abscission, including its negative impact on cells and the potential to induce tumor formation in humans. Finally, we propose a novel factor for improving cancer therapy and give future perspectives in this research field.

Cell cycle checkpoints, oncogene-induced senescence and programmed cell death represent intrinsic barriers to tumorigenesis. Protein phosphatase magnesium-dependent 1 (PPM1D) is a negative regulator of the tumour suppressor p53 and has been implicated in termination of the DNA damage response. Here, we addressed the consequences of increased PPM1D activity resulting from the gain-of-function truncating mutations in exon 6 of the PPM1D. We show that while control cells permanently exit the cell cycle and reside in senescence in the presence of DNA damage caused by ionising radiation or replication stress induced by the active RAS oncogene, RPE1-hTERT and BJ-hTERT cells carrying the truncated PPM1D continue proliferation in the presence of DNA damage, form micronuclei and accumulate genomic rearrangements revealed by karyotyping. Further, we show that increased PPM1D activity promotes cell growth in the soft agar and formation of tumours in xenograft models. Finally, expression profiling of the transformed clones revealed dysregulation of several oncogenic and tumour suppressor pathways. Our data support the oncogenic potential of PPM1D in the context of exposure to ionising radiation and oncogene-induced replication stress.