Epigenetic-Metabolic Interplay in the DNA Damage Response and Therapeutic Resistance of Breast Cancer

Tumor Metastasis: Mechanistic Insights and Therapeutic Intervention

Metastasis remains a leading cause of cancer‐related deaths, defined by a complex, multi‐step process in which tumor cells spread and form secondary growths in distant tissues. Despite substantial progress in understanding metastasis, the molecular mechanisms driving this process and the development of effective therapies remain incompletely understood. Elucidating the molecular pathways governing metastasis is essential for the discovery of innovative therapeutic targets. The rapid advancements in sequencing technologies and the expansion of biological databases have significantly deepened our understanding of the molecular drivers of metastasis and associated drug resistance. This review focuses on the molecular drivers of metastasis, particularly the roles of genetic mutations, epigenetic changes, and post‐translational modifications in metastasis progression. We also examine how the tumor microenvironment influences metastatic behavior and explore emerging therapeutic strategies, including targeted therapies and immunotherapies. Finally, we discuss future research directions, stressing the importance of novel treatment approaches and personalized strategies to overcome metastasis and improve patient outcomes. By integrating contemporary insights into the molecular basis of metastasis and therapeutic innovation, this review provides a comprehensive framework to guide future research and clinical advancements in metastatic cancer.

The role of glycolysis in tumorigenesis: From biological aspects to therapeutic opportunities

Glycolytic metabolism generates energy and intermediates for biomass production. Tumor-associated glycolysis is upregulated compared to normal tissues in response to tumor cell-autonomous or non-autonomous stimuli. The consequences of this upregulation are twofold. First, the metabolic effects of glycolysis become predominant over those mediated by oxidative metabolism. Second, overexpressed components of the glycolytic pathway (i.e. enzymes or metabolites) acquire new functions unrelated to their metabolic effects and which are referred to as "moonlighting" functions. These functions include induction of mutations and other tumor-initiating events, effects on cancer stem cells, induction of increased expression and/or activity of oncoproteins, epigenetic and transcriptional modifications, bypassing of senescence and induction of proliferation, promotion of DNA damage repair and prevention of DNA damage, antiapoptotic effects, inhibition of drug influx or increase of drug efflux. Upregulated metabolic functions and acquisition of new, non-metabolic functions lead to biological effects that support tumorigenesis: promotion of tumor initiation, stimulation of tumor cell proliferation and primary tumor growth, induction of epithelial-mesenchymal transition, autophagy and metastasis, immunosuppressive effects, induction of drug resistance and effects on tumor accessory cells. These effects have negative consequences on the prognosis of tumor patients. On these grounds, it does not come to surprise that tumor-associated glycolysis has become a target of interest in antitumor drug discovery. So far, however, clinical results with glycolysis inhibitors have fallen short of expectations. In this review we propose approaches that may allow to bypass some of the difficulties that have been encountered so far with the therapeutic use of glycolysis inhibitors.

Cancer metabolic reprogramming and precision medicine-current perspective

Despite the advanced technologies and global attention on cancer treatment strategies, cancer continues to claim lives and adversely affects socio-economic development. Although combination therapies were anticipated to eradicate this disease, the resilient and restorative nature of cancers allows them to proliferate at the expense of host immune cells energetically. This proliferation is driven by metabolic profiles specific to the cancer type and the patient. An emerging field is exploring the metabolic reprogramming (MR) of cancers to predict effective treatments. This mini-review discusses the recent advancements in cancer MR that have contributed to predictive, preventive, and precision medicine. Current perspectives on the mechanisms of various cancer types and prospects for MR and personalized cancer medicine are essential for optimizing metabolic outputs necessary for personalized treatments.

Curcumin improves atrial fibrillation susceptibility by regulating tsRNA expression in aging mouse atrium

Age is an independent risk factor for atrial fibrillation (AF), and curcumin can delay aging related disease through reducing oxidative stress and inflammation. However, its target in aging-related AF remains unclear. Transfer RNA-derived small RNA (tsRNA) is a novel short non-coding RNA (sncRNA), and exerts a potential regulatory function in aging. This study was to explore the therapeutic targets of curcumin in atrium of aged mice by PANDORA-seq. Aged mice (18 month) were treated with curcumin (100 mg/kg). Rapid transjugular atrial pacing was performed to observe AF inducibility. SA-β-gal staining, reactive oxygen species (ROS) detection and qRT-PCR were used to assess the degree of aging and oxidative stress/inflammation levels. PANDORA-seq was performed to reveal the differentially expressed sncRNAs in the atrium of mice. The results showed that curcumin reduced the susceptibility AF of aged mice by improving aging-related atrial fibrosis. Compared to young mice (5 month) group, aged mice yielded 473 significantly altered tsRNA sequences, while 947 tsRNA sequences were significantly altered after treated with curcumin. Enrichment analysis revealed that the target genes were mainly related to DNA damage and protein modification. Compared with the 5 month group, the expression levels of mature-mt_tRNA-Val-TAC_CCA_end, mature-mt_tRNA-Glu-TTC_CCA_end, and mature-tRNA-Asp-GTC_CCA_end were up-regulated in the 18 month group, while the expression of mature-mt_tRNA-Thr-TGT_5_end was down-regulated. This trend was reversed in the 18 month + curcumin group. Increased cellular ROS levels, inflammation expression and senescence in aged mice atrium were improved by the down-regulation of mature-mt_tRNA-Val-TAC_CCA_end. In conclusion, our findings identified mature-mt_tRNA-Val-TAC_CCA_end participated in the mechanism of aging-related atrial fibrosis, providing new intervention target of aging-related AF.

Mechanism of Histone Arginine Methylation Dynamic Change in Cellular Stress

Histone arginine residue methylation is crucial for individual development and gene regulation. However, the dynamics of histone arginine methylation in response to cellular stress remains largely unexplored. In addition, the interplay and regulatory mechanisms between this and other histone modifications are important scientific questions that require further investigation. This study aimed to investigate the changes in histone arginine methylation in response to DNA damage. We report a global decrease in histone H3R26 symmetric dimethylation (H3R26me2s) and hypoacetylation at the H3K27 site in response to DNA damage. Notably, H3R26me2s exhibits a distribution pattern similar to that of H3K27ac across the genome, both of which are antagonistic to H3K27me3. Additionally, histone deacetylase 1 (HDAC1) may be recruited to the H3R26me2s demethylation region to mediate H3K27 deacetylation. These findings suggest crosstalk between H3R26me2s and H3K27ac in regulating gene expression.

The future of cancer treatment: combining radiotherapy with immunotherapy

Radiotherapy (RT) and immunotherapy (IT) are the powerful tools for cancer treatment which act through the stimulation of immune response, and evidence suggest that combinatorial actions of these therapies may augment each other's beneficial effect through complex synergistic mechanisms. These molecular strategies are designed to target rapidly dividing cancer cells by either directly or indirectly inducing DNA damage. However, when cells detect DNA damage, they activate a range of signalling pathways known as the DNA damage response (DDR) to repair. Strategies are being developed to interfere with the DDR pathways in cancer cells to ensure their damage-induced degeneration. The stability of a cell's genetic material is largely dependent on the efficacy of DNA repair and therefore, an in-depth understanding of DNA damages and repair mechanism(s) in cancer cells is important to develop a promising therapeutic strategies for ensuring the efficacy of damage-induced tumor cell death. In recent years, a wide range of small molecule drugs have been developed which are currently being employed to combat the DNA repair deficiencies associated with tumor cells. Sequential or concurrent use of these two modalities significantly enhances the anti-tumor response, however with a concurrent probability of increased incidence of symptomatic adverse effects. With advent of newer IT agents, and administration of higher doses of radiation per fraction, such effects are more difficult to predict owing to the paucity of randomized trial data. It is well established that anti cytotoxic-T-lymphocyte-associated antigen 4 (CTLA-4), anti- Programmed cell death protein 1(PD-1), anti-Programmed cell death one ligand 1 (PD-L1) can be safely administered with RT and many studies have demonstrated survival benefit with such combination for patients with metastatic malignancy. However, the biology of radioimmunotherapy (RT/IT) is still an open area where research need to be focused to determine optimum dosage specially the interaction of the RT/IT pathways to determine optimum dosing schedule. In the current article we have summarised the possible intracellular immunological events that might be triggered when RT and IT modalities are combined with the DDR antagonists and highlighted present clinical practices, outcome, and toxicity profile of this novel treatment strategy.

Epigenetic modulations in triple-negative breast cancer: Therapeutic implications for tumor microenvironment

Triple-negative breast cancer (TNBC) is an aggressive subtype lacking estrogen receptors, progesterone receptors and lacks HER2 overexpression. This absence of critical molecular targets poses significant challenges for conventional therapies. Immunotherapy, remarkably immune checkpoint blockade, offers promise for TNBC treatment, but its efficacy remains limited. Epigenetic dysregulation, including altered DNA methylation, histone modifications, and imbalances in regulators such as BET proteins, plays a crucial role in TNBC development and resistance to treatment. Hypermethylation of tumor suppressor gene promoters and the imbalance of histone methyltransferases such as EZH2 and histone deacetylases (HDACs) profoundly influence tumor cell proliferation, survival, and metastasis. In addition, epigenetic alterations critically shape the tumor microenvironment (TME), including immune cell composition, cytokine signaling, and immune checkpoint expression, ultimately contributing to immune evasion. Targeting these epigenetic mechanisms with specific inhibitors such as EZH2 and HDAC inhibitors in combination with immunotherapy represents a compelling strategy to remodel the TME, potentially overcoming immune evasion and enhancing therapeutic outcomes in TNBC. This review aims to comprehensively elucidate the current understanding of epigenetic modulation in TNBC, its influence on the TME, and the potential of combining epigenetic therapies with immunotherapy to overcome the challenges posed by this aggressive breast cancer subtype.

Glutamine inhibition combined with CD47 blockade enhances radiotherapy-induced ferroptosis in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is a formidable cancer type that poses significant treatment challenges, including radiotherapy (RT) resistance. The metabolic characteristics of tumors present substantial obstacles to cancer therapy, and the relationship between RT and tumor metabolism in HNSCC remains elusive. Ferroptosis is a type of iron-dependent regulated cell death, representing an emerging disease-modulatory mechanism. Here, we report that after RT, glutamine levels rise in HNSCC, and the glutamine transporter protein SLC1A5 is upregulated. Notably, blocking glutamine significantly enhances the therapeutic efficacy of RT in HNSCC. Furthermore, inhibition of glutamine combined with RT triggers immunogenic tumor ferroptosis, a form of nonapoptotic regulated cell death. Mechanistically, RT increases interferon regulatory factor (IRF) 1 expression by activating the interferon signaling pathway, and glutamine blockade augments this efficacy. IRF1 drives transferrin receptor expression, elevating intracellular Fe2+ concentration, disrupting iron homeostasis, and inducing cancer cell ferroptosis. Importantly, the combination treatment-induced ferroptosis is dependent on IRF1 expression. Additionally, blocking glutamine combined with RT boosts CD47 expression and hinders macrophage phagocytosis, attenuating the treatment effect. Dual-blocking glutamine and CD47 promote tumor remission and enhance RT-induced ferroptosis, thereby ameliorating the tumor microenvironment. Our work provides valuable insights into the metabolic and immunological mechanisms underlying RT-induced ferroptosis, highlighting a promising strategy to augment RT efficacy in HNSCC.

Polo-like kinase 4 promotes tumorigenesis and glucose metabolism in glioma by activating AKT1 signaling

Glioblastoma (GBM) is an extremely aggressive tumor associated with a poor prognosis that impacts the central nervous system. Increasing evidence suggests an inherent association between glucose metabolism dysregulation and the aggression of GBM. Polo-like kinase 4 (PLK4), a highly conserved serine/threonine protein kinase, was found to relate to glioma progression and unfavorable prognosis. As revealed by the integration of proteomics and phosphoproteomics, PLK4 was found to be involved in governing metabolic processes and the PI3K/AKT/mTOR pathway. For the first time, this study supports evidence demonstrating that PLK4 activated PI3K/AKT/mTOR signaling through direct binding to AKT1 and subsequent phosphorylating AKT1 at S124, T308, and S473 to promote tumorigenesis and glucose metabolism in glioma. In addition, PLK4-mediated phosphorylation of AKT1 S124 significantly augmented the phosphorylation of AKT1 S473. Therefore, PLK4 exerted an influence on glucose metabolism by stimulating PI3K/AKT/mTOR signaling. Additionally, the expression of PLK4 protein exhibited a positive correlation with AKT1 phosphorylation in glioma patient tissues. These findings highlight the pivotal role of PLK4-mediated phosphorylation of AKT1 in glioma tumorigenesis and dysregulation of glucose metabolism.

Understanding Cancer's Defense against Topoisomerase-Active Drugs: A Comprehensive Review

In recent years, the emergence of cancer drug resistance has been one of the crucial tumor hallmarks that are supported by the level of genetic heterogeneity and complexities at cellular levels. Oxidative stress, immune evasion, metabolic reprogramming, overexpression of ABC transporters, and stemness are among the several key contributing molecular and cellular response mechanisms. Topo-active drugs, e.g., doxorubicin and topotecan, are clinically active and are utilized extensively against a wide variety of human tumors and often result in the development of resistance and failure to therapy. Thus, there is an urgent need for an incremental and comprehensive understanding of mechanisms of cancer drug resistance specifically in the context of topo-active drugs. This review delves into the intricate mechanistic aspects of these intracellular and extracellular topo-active drug resistance mechanisms and explores the use of potential combinatorial approaches by utilizing various topo-active drugs and inhibitors of pathways involved in drug resistance. We believe that this review will help guide basic scientists, pre-clinicians, clinicians, and policymakers toward holistic and interdisciplinary strategies that transcend resistance, renewing optimism in the ongoing battle against cancer.

Targeted Delivery of Potent Chemical Drugs and RNAi to Drug-Resistant Breast Cancer Using RNA-Nanotechnology and RNA-Ligand Displaying Extracellular vesicles

This review describes a new technology to treat breast-cancer-drug-resistance by targeting the ABC as the multi-homo-subunit ATPase, enlightening by the Christmas-lighting budge with serial circuit and the asymmetrical homo-hexamer of the phi29 DNA packaging motor with sequential revolving mechanism. Chemotherapeutics has been widely used in breast cancer treatments, but drug resistance has raised a serious concern. RNA therapeutics has emerged as the third milestone in pharmaceutical drug development. RNA nanoparticles are dynamic, mild, and deformative, resulting in spontaneous, rapid, and efficient accumulation in tumor vasculature after IV injection. Their negative charge and favorable size bypass the nonspecific targeting of vital organs and normal cells. This motile and deformable nature also led to the fast passing of glomerular filters and their movement into the urine for rapid body clearance for those non-tumor-accumulated nanoparticles, resulting in undetectable toxicity. Extracellular vesicles have shown potential as a delivery system for RNAi and chemotherapeutic drugs in vivo, contributing to the efficacy of cancer remission. However, the lack of cell-targeting ligands on extracellular vesicles and the nonspecific entry into healthy cells has led to safety concerns. This review addresses how to apply RNA nanotechnology and RNA-ligand displaying extracellular vesicles for specific delivery to breast cancer. The particular focus is on using and combining the RNA and extracellular vesicle technology to deal with breast cancer drug resistance. The targeting capabilities and drug safety can be improved through extracellular vesicle engineering techniques, such as affixing ligands on the extracellular vesicle surface utilizing arrow-tail RNA nanoparticles, ultimately addressing off-target effects and toxicity. Using RNA ligands for specific targeting and the efficient membrane fusion of extracellular vesicles has enabled the development of ligand-displayed extracellular vesicles capable of delivering both RNAi and chemical drugs to cells with precision, effectively inhibiting tumor growth. The negative charge inherent in the vesicles results in electrostatic repulsion, reducing non-specific binding to healthy cells that contain negatively charged lipid membranes. By leveraging the principles of RNA nanotechnology, the engineering of extracellular vesicles offers a promising avenue for addressing breast cancer drug resistance. This review also discusses applying the series of circuit mechanisms in Christmas-decorating-lighting to develop effective therapeutics to combat breast cancer chemoresistance by targeting the ABC drug transporter and breast cancer surface receptors.

A molecular classification system for estimating radiotherapy response and anticancer immunity for individual breast cancer patients

Objective

Radiotherapy is a cornerstone of breast cancer therapy, but radiotherapy resistance is a major clinical challenge. Herein, we show a molecular classification approach for estimating individual responses to radiotherapy.

Methods

Consensus clustering was adopted to classify radiotherapy-sensitive and -resistant clusters in the TCGA-BRCA cohort based upon prognostic differentially expressed radiotherapy response-related genes (DERRGs). The stability of the classification was proven in the GSE58812 cohort via NTP method and the reliability was further verified by quantitative RT-PCR analyses of DERRGs. A Riskscore system was generated through Least absolute shrinkage and selection operator (LASSO) analysis, and verified in the GSE58812 and GSE17705. Treatment response and anticancer immunity were evaluated via multiple well-established computational approaches.

Results

We classified breast cancer patients as radiotherapy-sensitive and -resistant clusters, namely C1 and C2, also verified by quantitative RT-PCR analyses of DERRGs. Two clusters presented heterogeneous clinical traits, with poorer prognosis, older age, more advanced T, and more dead status in the C2. The C1 tumors had higher activity of reactive oxygen species and response to X-ray, proving better radiotherapeutic response. Stronger anticancer immunity was found in the C1 tumors that had rich immune cell infiltration, similar expression profiling to patients who responded to anti-PD-1, and activated immunogenic cell death and ferroptosis. The Riskscore was proposed for improving patient prognosis. High Riskscore samples had lower radiotherapeutic response and stronger DNA damage repair as well as poor anticancer immunity, while low Riskscore samples were more sensitive to docetaxel, doxorubicin, and paclitaxel.

Conclusion

Our findings propose a novel radiotherapy response classification system based upon molecular profiles for estimating radiosensitivity for individual breast cancer patients, and elucidate a methodological advancement for synergy of radiotherapy with ICB.