Search Results (1,463)

Tumour hypoxia significantly influences disease advancement and treatment resistance in oral squamous cell carcinoma (OSCC). Hypoxia-inducible factor-1α (HIF-1α) is preserved when oxygen is lacking and triggers the expression of hypoxia-responsive genes that have roles in angiogenesis, metabolic adaptability, tumour cell viability, invasion, and metastasis. The elevated levels of vascular endothelial growth factor (VEGF) induced by HIF-1α result in atypical angiogenesis. The dysfunction of cell junction proteins and heightened activity of matrix metalloproteinases caused by hypoxia facilitate cancer invasion and metastasis. Hypoxic stress prompts cellular modifications, including autophagy and the preservation of cancer cell populations with enhanced survival capabilities, hence facilitating tumour recurrence and heterogeneity. Hypoxia diminishes the effectiveness of standard chemotherapy and radiotherapy due to decreased drug transport, hindered cell growth, and diminished oxygen-dependent radiation-induced DNA damage. Thus, treatment strategies for the hypoxic tumour microenvironment encompass the suppression of HIF and VEGF, tumour reoxygenation, hypoxia radiosensitizers, and hypoxia-activated lethal compounds. Nonetheless, the diverse and fluctuating characteristics of tumour hypoxia, along with the initiation of compensatory survival mechanisms, continue to pose significant obstacles. Enhanced comprehension of hypoxia-induced molecular networks and the advancement of multimodal, biomarker-directed treatment strategies could improve outcomes in OSCC. Full article

Glioblastoma (GBM) standard of care includes surgical resection followed by ionizing radiation (IR) and Temozolomide, which induce DNA double-strand breaks. Homologous recombination (HR), a critical DNA double-strand break repair pathway, is augmented in GBM, contributing to resistance and poor patient outcomes. Here, we demonstrate that increasing deoxyribonucleoside triphosphate (dNTP) levels impairs HR-mediated double-strand break repair, rendering GBM cells sensitive to IR and Temozolomide. Interestingly, combining an elevated dNTP pool level with IR and/or Temozolomide promotes the recruitment of DNA polymerase-α/primase, which is typically involved in Okazaki fragment synthesis during DNA replication, to the DNA double-strand break site, thereby interfering with DNA end resection. Specifically, higher dNTP pool levels disrupted the recruitment of HR-associated proteins such as RPA70 and RAD51, an effect reversed by Aphidicolin, a DNA polymerase-α/primase inhibitor. Impaired HR delayed IR- and/or Temozolomide-induced DNA double-strand break repair, leading to growth arrest and apoptosis. Furthermore, higher dNTP pool levels led to downregulation of DNA replication and HR-associated genes, while upregulating several pro-apoptotic genes. Increased sensitivity to IR and Temozolomide was also observed in engineered IR-resistant GBM cell lines and in naturally recurrent patient-derived GBM cells that emerge post-therapy. These findings emphasize how dNTP pool levels regulate HR and uncover a promising vulnerability that could be exploited to overcome resistance to DNA-damaging treatments in GBM and beyond. Full article

Current studies have elucidated the mechanisms of radiation-induced skin injury (RISI) and identified several medical countermeasures to reduce its severity. However, no treatment has yet proven effective in preventing or reversing radiation-induced skin fibrosis. Here, we show that radiation upregulates lipoprotein-associated phospholipase A2 (Lp-PLA₂) expression and induces endothelial cell dysfunction, characterized by an increased DNA damage response and reduced tube-forming capacity and mitochondrial function. To define the role of Lp-PLA₂ in the progression of RISI, we treated human dermal microvascular endothelial cells and the skin of SKH1 hairless mice with darapladib, a selective Lp-PLA₂ inhibitor. In endothelial cells, darapladib attenuated radiation-induced cellular damage and suppressed endothelial-to-mesenchymal transition (EndoMT). In irradiated mouse skin, darapladib reduced radiation-induced inflammation, adipose tissue disruption, dermal thickness, and skin fibrosis. Notably, darapladib modulated macrophage polarization and inhibited radiation-induced macrophage infiltration in irradiated skin. These findings suggest that Lp-PLA₂ inhibition may reveal potential targets for the treatment of RISI and other fibrotic skin diseases. Full article

The gastrointestinal tract is a critical target of acute radiation exposure. Severe radiation exposure can deplete epithelial stem and progenitor cells, compromise barrier integrity, alter host–microbe interactions, and drive fluid loss, inflammation, and systemic decline. Mammalian models remain essential for clinical translation, but their cost and complexity constrain sample sizes, statistical power, large-scale mechanistic discovery, and countermeasure screening. The adult Drosophila melanogaster midgut provides a complementary in vivo platform containing intestinal stem cells, absorptive enterocytes, enteroendocrine cells, epithelial junctions, an associated microbiota, and conserved innate immune and injury-response pathways. Direct irradiation studies have demonstrated DNA damage, altered stem cell proliferation and differentiation, epithelial plasticity, apoptosis, autophagy-associated responses, morphological disruption, barrier failure, microbiome changes, and reduced survival. These phenotypes can be modulated by genotype, sex, diet, microbial status, antioxidant capacity, and regenerative signaling. This review evaluates the biological rationale, direct evidence, experimental assays, and countermeasure applications supporting the fly midgut as a model for studying gastrointestinal radiation injury. Although Drosophila has a long history of use in radiation research, our analysis indicates that the fly midgut is best positioned not as a miniature model of clinical gastrointestinal acute radiation syndrome, but as a genetically precise and scalable system for identifying conserved mechanisms and prioritizing interventions for validation in mammalian models. Full article

Glioblastoma is the most aggressive primary tumor of the central nervous system, characterized by high invasiveness, rapid progression, and a poor prognosis despite the current treatment modalities. Molecular stratification, using biomarkers such as IDH1, TERT, and MGMT, is a crucial step in the 2021 WHO classification for improving diagnosis and prognosis. Oxidative stress, a feature of GB, has been identified as an important factor in the initiation, progression, and resistance to treatment. It occurs due to an imbalance between reactive oxygen species generated by mitochondrial metabolism, NADPH oxidases, and exogenous sources such as ionizing radiation and xenobiotics and antioxidant defense. This imbalance leads to DNA damage, genomic instability, and deregulation of signaling pathways involved in cell proliferation, apoptosis, and tumor progression. This review provides an overview of key oxidative stress biomarkers and their dual roles in tumor suppression and progression. It highlights how oxidative stress contributes to treatment responses and resistance to current GB treatments, including redox-adaptive mechanisms such as the Nrf2–Keap1 pathway, which promotes radioresistance. Finally, it discusses the potential of understanding these mechanisms to develop therapeutic strategies that target redox balance and homeostasis, aiming to overcome resistance and improve survival outcomes for glioblastoma patients. Full article

Background: Radiation-induced sepsis resulting from intestinal inflammation and injury is a severe complication of high-dose radiation exposure. High-dose radiation compromises the integrity of the intestinal lining, causing bacterial translocation, systemic inflammation, and sepsis. Extracellular cold-inducible RNA-binding protein (eCIRP), a damage-associated molecular pattern, plays a pivotal role in the pathogenesis of inflammatory diseases and contributes to organ injury. C23, a small molecular peptide antagonist of eCIRP, has demonstrated anti-inflammatory and organ-protective effects during organ-injury indications. However, its role in radiation-induced inflammation and injury is not known. The objective of this study is to evaluate whether C23 mitigates inflammation and injury, leading to improved survival in a murine model of partial-body irradiation (PBI) combined with sepsis. Methods: Mice were exposed to 10 Gy PBI, and at 48 h, they were subjected to cecal ligation and puncture (CLP), a well-established model of sepsis. C23 (8 mg/kg body weight [BW]) or vehicle (saline) was administered subcutaneously at 24 h and 48 h after PBI. Blood and intestinal tissue samples were collected 20 h after CLP (i.e., 68 h post-PBI) for various analyses. In another set of mice after PBI–sepsis, intestinal permeability was also assessed. In an additional cohort of mice subjected to the same experimental procedure, 10-day survival was monitored. Results: Our findings demonstrate that administration of C23 attenuated systemic inflammatory responses, intestinal permeability, intestinal injury, and apoptosis; increased crypt cell proliferation and improved survival after PBI–sepsis. Conclusions: These results reveal a novel protective role of the eCIRP antagonist, C23, in mitigating PBI–sepsis-induced inflammation and injury and represents a promising therapeutic candidate for the treatment of radiation combined injury with sepsis. Full article

Background: Solid tumors including glioblastoma (GBM), lung cancer (LC), and triple-negative breast cancer (TNBC) exhibit marked radioresistance driven by dysregulated cell-cycle control and genomic instability. Although CDK4/6 inhibitors suppress tumor proliferation, their radiosensitizing capacity is limited by persistent DNA repair. BUB1, a mitotic checkpoint kinase overexpressed in aggressive cancers, has emerged as a regulator of DNA damage signaling. We tested whether co-targeting BUB1 and CDK4/6 enhances radiosensitivity across solid tumors. Methods: GBM, LC, and TNBC cell lines were treated with BUB1 inhibitor BAY1816032, CDK4/6 inhibitors ribociclib and abemaciclib, and radiation. Proliferation, clonogenic survival, immunoblotting, and combination index analyses assessed cytotoxicity and synergy. CDK4/6-resistant models were generated to examine resistance. In vivo efficacy was evaluated using SUM159 xenografts. DNA damage and homologous recombination repair were measured by gH2AX, RAD51, RPA, BrdU foci and comet assay. The resection branchpoint was assessed by phospho-RPA, with ATR inhibition and BLM or EXO1 depletion testing resection dependence. Results: BUB1 inhibition increased cytotoxicity in vitro and improved therapeutic response in vivo. Combined BUB1 and CDK4/6 inhibition showed strong synergy (C.I. < 1) and enhanced radiosensitization in RB+ models. CDK4/6-resistant cells displayed increased BUB1 expression, and BUB1 inhibition partially restored sensitivity. Mechanistically, dual inhibition intensified homologous recombination defects, marked by persistent gH2AX and altered RAD51, RPA, and BrdU dynamics, consistent with sustained single stranded DNA and impaired HR repair. Persistent RPA32 Ser33 phosphorylation reflects ATR-dependent resection that requires BLM and EXO1 at later stages, supporting sustained resection and unresolved repair leading to increased cell death. Conclusions: Dual inhibition of BUB1 and CDK4/6 represents a promising therapeutic strategy for enhancing radiosensitivity in GBM, lung cancer, and TNBC, particularly in Rb-intact settings. Full article

Ionizing radiation can induce DNA damage through direct or indirect mechanisms and activate the DNA damage response network, thereby influencing cellular repair, cell cycle regulation and cell fate determination. MicroRNAs (miRNAs), as key post-transcriptional regulatory factors, play a vital role in modulating the radiation response and cell fate. This review summarizes radiation-induced changes in miRNA expression and the molecular regulatory mechanisms they mediate, and further discusses recent advances in their application in the assessment of radiation damage, the prediction of radiotherapy response, and therapeutic interventions. Although miRNAs possess significant translational value, their multi-target regulatory characteristics, tissue- and environment-dependence, as well as limitations in clinical detection and delivery systems, continue to hinder their application. In the future, the integration of multi-omics technologies, artificial intelligence analysis and precision delivery strategies is expected to further elucidate the miRNA-mediated radiation response network and advance their application in precision radiology. Full article

Background: Tumor hypoxia is a major determinant of radioresistance, limiting oxygen-mediated fixation of radiation-induced DNA damage and promoting metabolic adaptation, tumor aggressiveness, and treatment failure. Nitroimidazole derivatives and related hypoxia-targeting compounds have been investigated as radiosensitizers because of their oxygen-mimetic properties and selective activation under low-oxygen conditions. Methods: A structured narrative review was conducted to evaluate recent evidence on hypoxia-targeting strategies and nitroimidazole-based radiosensitizers combined with radiotherapy. PubMed and Scopus were searched in March 2026 using terms related to radiotherapy and nitroimidazoles. Studies published within the last five years were included if they investigated hypoxia-targeting compounds, radiosensitization strategies, or dose–response relationships relevant to radiotherapy. Preclinical, computational, and clinical studies were considered. Results: Sixteen studies were included, comprising preclinical, computational, and clinical investigations. Most studies were preclinical and evaluated in vitro cell lines, murine tumor models, or xenografts across multiple tumor types, including head and neck cancer, glioblastoma, breast cancer, colorectal cancer, cervical cancer, renal carcinoma, pancreatic cancer, and ovarian-related models. Nitroimidazole-based and related hypoxia-targeting strategies generally enhanced radiation response under hypoxic conditions, with sensitizer enhancement ratio values ranging from approximately 1.09 to 1.65. In vivo studies reported reductions in tumor growth or tumor volume when radiosensitizers were combined with radiotherapy. Clinical evidence, mainly in head and neck squamous cell carcinoma, showed variable effects on locoregional outcomes. Conclusions: Current evidence supports the biological relevance of hypoxia-targeting strategies for improving radiotherapy response. Nitroimidazole-based compounds show consistent radiosensitizing effects in preclinical models, but clinical translation remains heterogeneous. Future studies should integrate hypoxia imaging, standardized endpoints, advanced drug delivery systems, and clinically relevant radiotherapy models to better define their role in modern radiation oncology. Full article

Sphingolipid metabolism has emerged as a regulatory interface between lipid homeostasis, organelle stress, and genome maintenance. Although sphingolipids are essential structural components of cellular membranes, specific metabolites also function as bioactive mediators that shape cellular responses to genotoxic stress. In this review, we examine how canonical and atypical sphingolipid pathways influence the DNA damage response through three mechanistic axes. First, ceramide-centered stress signaling links radiation, chemotherapy, and inflammatory injury to kinase and phosphatase pathways, mitochondrial apoptosis, and checkpoint-associated cell-fate decisions. Second, nuclear sphingolipid metabolism, particularly sphingosine kinase 2-dependent production of sphingosine-1-phosphate, regulates chromatin-associated transcriptional programs through modulation of histone deacetylase activity. Third, persistent sphingolipid imbalance promotes metabolic stress by disrupting lysosomal turnover, mitochondrial function, endoplasmic reticulum homeostasis, and redox balance, thereby increasing endogenous oxidative DNA damage. We also discuss atypical sphingolipids, including 1-deoxysphingolipids generated through altered serine palmitoyltransferase substrate utilization, as emerging mediators of mitochondrial dysfunction and genome instability. Finally, we consider the relevance of these mechanisms to cancer, lysosomal storage disorders, and neurodegenerative diseases, where sphingolipid dysregulation may influence therapeutic responses and disease progression. Together, these position sphingolipid metabolism as an integrated regulatory network connecting cellular stress signaling, chromatin regulation, organelle dysfunction, and genome stability. Full article

Background/Objectives: The emergence of radioresistance is a major challenge in cancer treatment. Herein, we evaluated the radiosensitizing effects and associated molecular mechanisms of a small molecule, berberine, in HNSCC. Methods: HNSCC cells were treated with berberine, ionizing radiation (IR), and their combination. Radiosensitivity was assessed using methods for clonogenic survival, proliferation, cell death, apoptosis, cell cycle distribution, DNA damage, and associated mechanisms. Spheroid models were employed to examine tumor growth and stemness-related markers. Therapeutic efficacy was further evaluated using the syngeneic MOC2 tumor syngraft mouse model. Results: The combination of berberine and IR significantly decreased the colony-forming ability, cell proliferation, and survival in UM-SCC-22B and MOC2 cells. Correspondingly, a decrease in the pro-survival signaling, EGFR, ERK1/2, mTOR, and STAT-3 was noted. The combination treatment increased sub-G1 cell population and apoptotic cell death with enhanced DNA damage, which was also associated with downregulation of DNA repair proteins. Spheroids showed disintegration and altered morphology in the combination treatment. This combination also inhibited Wnt/β-catenin signaling and reduced the expression of genes associated with stemness-related pluripotency. Berberine further enhanced DNA damage and reduced stemness in EGFR-knockdown cells. The berberine-IR combination not only inhibited the growth of syngeneic MOC2 tumors but also mitigated the toxicity associated with IR. The in vitro findings of reduced expression of stemness and DNA damage repair genes were also observed in tumors. Conclusions: Our findings indicated that berberine enhances the radiation response of HNSCC through perturbation of pro-survival signaling, DDR signaling and reduction of stemness-associated features, thereby enhancing the therapeutic efficacy. Full article

Apoptosis is traditionally considered a definitive barrier against oncogenesis, as caspase activation typically eliminates damaged and genetically unstable cells. Here, we report that caspase-8, an initiator of extrinsic apoptosis, paradoxically promotes genetic instability and carcinogenesis following exposure to radiation. We observed that a substantial fraction of mammalian cells exposed to ionizing radiation can survive despite caspase-8 activation. This sublethal activation of caspase-8 facilitated persistent DNA damage, which was attenuated by the expression of a dominant-negative caspase-8 (C360A, Casp8DN) or short hairpin RNA (shRNA)-mediated knockdown of caspase-8 in mammalian cells. The facilitative role of caspase-8 in radiation-induced genomic instability was further validated in caspase-8 heterozygous mice. Moreover, inhibition of caspase-8 abolished iron-ion radiation-induced oncogenic transformation in both soft agar and nude mice. Mechanistically, sublethal caspase-8 activation promoted the nuclear translocation of mitochondrial endonuclease G and persistent DNA damage, accompanied by activation of non-canonical nuclear factor κB (NF-κB) signaling. Collectively, our findings demonstrate that caspase-8 can act as a causative driver of radiation-induced malignancy, challenging the dogma of caspases as universal anticancer barriers and providing important insights into the long-term health risks associated with space radiation and radiotherapy. Full article

Radiosensitizers are being investigated to improve the therapeutic efficacy of radiotherapy by enhancing tumor cell sensitivity while minimizing damage to normal tissues. Dihydroquinine (DHQ), a naturally occurring Cinchona alkaloid with diverse biological activities, has not previously been evaluated for radiosensitizing potential. In this study, human cervical cancer (HeLa) cells were pretreated with an IC20 concentration of DHQ and exposed to 6 MV X-ray irradiation. Clonogenic survival was assessed after irradiation at 2, 4, and 6 Gy, while intracellular ROS, γ-H2AX immunofluorescence, and apoptosis were evaluated following DHQ pretreatment and 2 Gy irradiation. DHQ pretreatment reduced clonogenic survival, yielding sensitizer enhancement ratio values of 1.37 and 1.55 at surviving fractions of 0.20 and 0.37, respectively, indicating modest-to-moderate enhancement of radiosensitivity. DHQ was also associated with increased ROS production, elevated γ-H2AX positivity, and enhanced apoptosis compared with irradiation alone. These findings suggest that DHQ enhances the radiation response in HeLa cells and is associated with increased radiation-induced cellular responses. Although the radiosensitizing effect was modest, the consistent findings across multiple biological endpoints support further investigation of DHQ as a potential adjunct to radiotherapy. Further studies are warranted to validate these findings in more clinically relevant preclinical models. Full article

Hair follicle homeostasis is influenced by hormonal pathways, the scalp microenvironment, and environmental stressors such as pollution, UV radiation, and oxidative stress. Elissara^®, a polyphenol-enriched botanical ingredient, has shown benefits for scalp moisturization, barrier function, sebum regulation, and redness. Building on these scalp-level benefits, we investigated Elissara’s effects on follicular signaling, survival-associated biomarkers, oxidative damage, and androgen-related pathways as potential contributors to follicular health, using in silico, in vitro, and ex vivo models. Molecular docking (AutoDock Vina) of the main Elissara bioactives (oleuropein, hydroxytyrosol, verbascoside, carnosic acid, carnosol, and quercetin) identified SRD5A2 as a favorable predicted target, with individual binding energies ranging from −8.70 to −9.73 kcal/mol, approaching finasteride/dutasteride reference values. As an exploratory approach, simultaneous multi-ligand docking showed favorable global docking outputs for several targets, indicating that multiple bioactives could be structurally accommodated within complementary regions of the binding site. In human follicle dermal papilla cells, Elissara significantly increased BrdU incorporation to 245.70% of control at 0.002% and reduced SRD5A2 protein levels by 18.48% at 0.006%. In human scalp explants, Elissara at 200 µg/mL increased β-catenin, Bcl-2, and collagen IV under basal conditions and counteracted acute PM_2.5/UVA-induced alterations in β-catenin, Ki67-positive cells, Bcl-2, IGF-1, collagen IV, and protein carbonylation. Together, these findings support the potential of Elissara as a promising nutricosmetic ingredient for supporting follicular resilience through multiple follicle-relevant pathways. Clinical studies assessing hair growth outcomes are needed to determine whether these preclinical findings translate into measurable benefits. Full article

Background/Objectives: High linear energy transfer (LET) carbon ions achieved more effective and biologically robust tumor control than photons in preclinical prostate cancer models; however, the longitudinal development of histopathological parameters remains insufficiently characterized, limiting the selection of the optimal treatment modality in patients. This study analyzed the temporal histological patterns after isoeffective photon, proton, and carbon ion irradiations. Methods: Two Dunning R3327 prostate carcinoma sublines (H, HI) grown subcutaneously in male Copenhagen rats received single-fraction isoeffective curative photon or carbon ion doses. For HI-tumors, the effectiveness of isoeffective curative proton doses and isoeffective subcurative photon and carbon ion doses was additionally investigated. Tumors were collected prior and up to 3 weeks after irradiation and processed for quantitative histology of proliferation (BrdU), DNA damage (γH2AX), hypoxia (pimonidazole), vascular (CD31), and immune cell (CD3, CD68) markers. Results: All modalities induced an early peak in γH2AX⁺ tumor cells and a pronounced suppression of BrdU⁺ cells, with more sustained effects after isoeffective carbon ions doses, particularly in the HI-tumors. These findings, however, differed strongly between hypoxic and oxic micro-environments. Vascular parameters, diffusion distances, and global and compartment-specific hypoxic fractions showed distinct temporal dynamics between photons and carbon ions in HI-tumors, whereas H-tumors exhibited more moderate and reversible changes. At curative carbon ion doses, there was a late rebound of BrdU-positive tumor cells and increased CD68⁺ macrophage accumulation in chronically hypoxic regions. CD3⁺ T cells showed a biphasic decrease-recovery pattern in HI-tumors largely independent of radiation quality and oxygenation. Conclusions: Longitudinal histology revealed modality- and tumor-line-specific trajectories of tumor, vascular, hypoxic, and immune responses after isoeffective photon, proton, and carbon ion irradiations in prostate carcinoma. The more persistent tumor cell damage and distinct vascular response, together with late proliferative and macrophage rebounds under chronic hypoxia after carbon ions, provide mechanistic support for the increased biological effectiveness and highlight hypoxia-driven repopulation and inflammation as key processes. Full article