Radiation Sensitivity Research Articles

Metformin-loaded chitosan nanoparticles augment silver nanoparticle-induced radiosensitization in breast cancer cells during radiation therapy

Recent research has focused on enhancing tumor response to radiation therapy using radiosensitizers to increase radiation absorption by cancerous tissues. This study utilized silver nanoparticles (AgNPs) as radiation sensitizers and chitosan as a nanocarrier to deliver metformin to breast cancer cells. Metformin-loaded chitosan nanoparticles (Met NPs) and AgNPs were synthesized and characterized. MCF-7 breast cancer cells were pretreated with Met NPs, followed by treatment with AgNPs and irradiation with X-rays at 2, 4, and 8 Gy doses. Cellular cytotoxicity, apoptosis, DNA damage, and 3D spheroid formation were evaluated. The synthesized Met NPs and AgNPs had average diameters of 51.5 ± 9.4 nm and 3.02 ± 0.03 nm, respectively. Cellular cytotoxicity assessment revealed the highest cytotoxicity in MCF-7 cells pretreated with Met NPs, treated with AgNPs, and irradiated with 8 Gy. Flow cytometry analysis demonstrated a 67.58 % apoptosis rate in cells pretreated with Met NPs, compared to 30.42 % in cells pretreated with plain metformin. DAPI staining revealed a 1.8-fold increase in DNA damage in cells pretreated with Met NPs and Ag NPs upon exposure to radiation. The 3D spheroid culture model confirmed a 60 % enhancement in the radiosensitivity of breast cancer cells in the presence of Met NPs and Ag NPs. The combination of Met NPs and Ag NPs represents a promising strategy to improve the therapeutic efficacy of radiation therapy for breast cancer treatment. The delivery of metformin can potentiate the radiosensitizing effects of Ag NPs, offering a novel approach to enhance cancer cells' response to radiation.

A review of criticality dosimetry at the Y-12 National Security Complex and practical importance of dose accuracy in emergency response

A nuclear criticality results in the emission of both neutron and gamma radiation and can produce doses to personnel near the event that exceed 0.1 Gy (10 rad). The primary purpose of nuclear accident dosimetry is to rapidly identify affected personnel in need of prompt medical treatment and to reassure personnel who have been only minimally exposed. While accurate dosimetry is desired, it must be recognized that dose determinations made from whole-body dosimeters or simple triage methods are very rough estimates and contain significant uncertainties. Even when accounting for factors like varying neutron energy spectra, mean photon energies, body orientation within the radiation field, and transient effects on dosimeter response, etc., the end value is a dosimetric quantity defined for very specific radiological conditions and determined within a simple phantom usually at a single depth. Of more importance is the biological response to the radiation, which will vary by person and can be affected by the individual's radiation sensitivity, age, gender, mass, and underlying health conditions. The overall biological, person-specific response to a given dose cannot be precisely determined except by patient symptom observation and individual biological dosimetry (e.g. chromosome analysis, lymphocyte ratios, etc.). This work describes and discusses the criticality accident dosimetry program at the Y-12 National Security Complex, a United States Department of Energy National Nuclear Security Administration facility. The primary goals of the Y-12 accident dosimetry program are, among others, the rapid identification of significantly exposed persons, prompt routing of exposed workers for medical evaluation and treatment, and the ultimate processing of dosimeters to assign doses to personnel.

Deciphering colorectal cancer radioresistance and immune microrenvironment: unraveling the role of EIF5A through single-cell RNA sequencing and machine learning.

Radiotherapy (RT) is a critical component of treatment for locally advanced rectal cancer (LARC), though patient response varies significantly. The variability in treatment outcomes is partly due to the resistance conferred by cancer stem cells (CSCs) and tumor immune microenvironment (TiME). This study investigates the role of EIF5A in radiotherapy response and its impact on the CSCs and TiME. Predictive models for preoperative radiotherapy (preRT) response were developed using machine learning, identifying EIF5A as a key gene associated with radioresistance. EIF5A expression was analyzed via bulk RNA-seq and single-cell RNA-seq (scRNA-seq). Functional assays and in vivo experiments validated EIF5A's role in radioresistance and TiME modulation. EIF5A was significantly upregulated in radioresistant colorectal cancer (CRC) tissues. EIF5A knockdown in CRC cell lines reduced cell viability, migration, and invasion after radiation, and increased radiation-induced apoptosis. Mechanistically, EIF5A promoted cancer stem cell (CSC) characteristics through the Hedgehog signaling pathway. Analysis of the TiME revealed that the radiation-resistant group had an immune-desert phenotype, characterized by low immune cell infiltration. In vivo experiments showed that EIF5A knockdown led to increased infiltration of CD8+ T cells and M1 macrophages, and decreased M2 macrophages and Tregs following radiation therapy, thereby enhancing the radiotherapy response. EIF5A contributes to CRC radioresistance by promoting CSC traits via the Hedgehog pathway and modulating the TiME to an immune-suppressive state. Targeting EIF5A could enhance radiation sensitivity and improve immune responses, offering a potential therapeutic strategy to optimize radiotherapy outcomes in CRC patients.

Synonymous rpsH variants: the common denominator in Escherichia coli adapting to ionizing radiation.

Ionizing radiation (IR) in high doses is generally lethal to most organisms. Investigating mechanisms of radiation resistance is crucial for gaining insights into the underlying cellular responses and understanding the damaging effects of IR. In this study, we conducted a comprehensive analysis of sequencing data from an evolutionary experiment aimed at understanding the genetic adaptations to ionizing radiation in Escherichia coli. By including previously neglected synonymous mutations, we identified the rpsH c.294T > G variant, which emerged in all 17 examined isolates across four subpopulations. The identified variant is a synonymous mutation affecting the 30S ribosomal protein S8, and consistently exhibited high detection and low allele frequencies in all subpopulations. This variant, along with two additional rpsH variants, potentially influences translational control of the ribosomal spc operon. The early emergence and stability of these variants suggest their role in adapting to environmental stress, possibly contributing to radiation resistance. Our findings shed light on the dynamics of ribosomal variants during the evolutionary process and their potential role in stress adaptation, providing valuable implications for understanding clinical radiation sensitivity and improving radiotherapy.

Dual role of targeting NAE1 in nasopharyngeal carcinoma: Antitumor effects yet inducing radiotherapy resistance

Background and objectivesThe inhibitor MLN4924 of Neural Precursor Cell-Expressed Developmentally Down-Regulated 8 (NEDD8) Activating Enzyme 1 (NAE1) has been found to suppress the growth of nasopharyngeal carcinoma (NPC). However, its effect on NPC's radiotherapy sensitivity remains unclear. MethodsBy integrating single-cell RNA sequencing and bulk RNA sequencing, we predict the impact of NAE1 on the cell cycle, cell death, and its relationship with radiotherapy sensitivity and prognosis in NPC. The effect of inhibiting NAE1 on NPC cell behavior and radiation sensitivity is explored through MLN4924 intervention in vitro and in vivo. We construct a prognosis prediction model based on NAE1 using machine learning methods and validate the efficacy of NAE1 and the model in clinical cohorts. ResultsNPC patients with high NAE1 expression have better prognosis and higher expression in the radiotherapy-sensitive group. Inhibiting NAE1 with MLN4924 causes cell cycle arrest in NPC cells, preventing them from entering the G2/M phase, thereby inhibiting proliferation but not affecting migration and metastasis. However, in vitro and in vivo experiments demonstrate that inhibiting NAE1 with MLN4924 leads to increased resistance of NPC to radiation. ConclusionsTargeting NAE1 for NPC treatment may have dual effects, inhibiting NPC proliferation while also increasing radiation resistance.

1715: Pathological Phenotypes and Radiation Sensitivity of Airway Stem Cells Derived from COPD Patients.

1715: Pathological Phenotypes and Radiation Sensitivity of Airway Stem Cells Derived from COPD Patients.

Exposure to endocrine disruptor DEHP promotes the progression and radiotherapy resistance of pancreatic cancer cells by increasing BMI1 expression and properties of cancer stem cells

Most patients diagnosed with pancreatic cancer are initially at an advanced stage, and radiotherapy resistance impact the effectiveness of treatment. This study aims to investigate the effects of endocrine disruptor Di-(2-ethylhexyl) phthalate (DEHP) on various biological behaviors and the radiotherapy sensitivity of pancreatic cancer cells, as well as its potential mechanisms. Our findings indicate that exposure to DEHP promotes the proliferation of various cancer cells, including those from the lung, breast, pancreas, and liver, in a time- and concentration-dependent manner. Furthermore, DEHP exposure could influence several biological behaviors of pancreatic cancer cells in vivo and vitro. These effects include reducing cell apoptosis, causing G0/G1 phase arrest, increasing migration capacity, enhancing tumorigenicity, elevating the proportion of cancer stem cells (CSCs), and upregulating expression levels of CSCs markers such as CD133 and BMI1. DEHP exposure can also increase radiation resistance, which can be reversed by downregulating BMI1 expression. In summary our research suggests that DEHP exposure can lead to pancreatic cancer progression and radiotherapy resistance, and the mechanism may be related to the upregulation of BMI1 expression, which leads to the increase of CSCs properties.

Correlation between gut microbiota characteristics and non-small cell lung cancer based on macrogenomics sequencing

ObjectiveNon-small cell lung cancer (NSCLC) patients undergoing chemotherapy and immunotherapy experience disturbances in the gut microbiota. This study intends to find out the correlation between gut microbiota and clinical indices before and after radiotherapy for NSCLC.MethodsTen patients with primary NSCLC were screened, and plasma and fecal samples were collected before and after radiotherapy, respectively. Inflammatory indices in plasma were detected. Genomic DNA was extracted from fecal specimens and sequenced on on Illumina HiSeq2000 sequencing platform. Thee sequenced data were subjected to Metagenome assembly, gene prediction, species annotation, and gene function analysis to study and analyze gut microbiota and metabolic functions. The correlation between the diversity of gut microbiota and the clinical indicators of NSCLC patients was evaluated, and the changes of gut microbiota before and after radiotherapy were observed.ResultsThe diversity of gut microbiota in NSCLC patients did not correlate with smoking, pathology, and inflammatory markers. The abundance of phylum (p)_Bacteroidetes increased; p_Firmicutes and p_Bacteroidetes accounted for the highest proportion in NSCLC patients, and the abundance of both was dominantly exchanged after radiotherapy. There was a decrease in genus (g)_Bifidobacterium after radiotherapy in NSCLC patients. There was no significant correlation between the diversity of gut microbiota after radiotherapy and radiotherapy sensitivity, and the structural composition and abundance of gut microbiota remained stable.ConclusionThe diversity of gut microbiota is altered after radiotherapy in NSCLC patients, showing an increase in harmful bacteria and a decrease in beneficial bacteria.

Photobleaching Effect on the Sensitivity Calibration at 638 nm of a Phosphorus-Doped Single-Mode Optical Fiber Dosimeter.

We investigated the influence of the photobleaching (PB) effect on the dosimetry performances of a phosphosilicate single-mode optical fiber (core diameter of 6.6 µm) operated at 638 nm, within the framework of the LUMINA project. Different irradiation tests were performed under ~40 keV mean energy fluence X-rays at a 530 µ Gy(SiO2)/s dose rate to measure in situ the radiation-induced attenuation (RIA) growth and decay kinetics while injecting a 638 nm laser diode source with powers varying from 500 nW to 1 mW. For injected continuous power values under 1 µW, we did not measure any relevant influence of the photobleaching effect on the fiber radiation sensitivity coefficient of ~140 dB km-1 Gy-1 up to ~30 Gy. Above 1 µW, the fiber radiation sensitivity is significantly reduced due to the PB associated with the signal and can decrease to ~80 dB km-1 Gy-1 at 1 mW, strongly affecting the capability of this fiber to serve as a dosimeter-sensitive element. Higher power values up to 50 µW can still be used by properly choosing a pulsed regime with periodic injection cycles to reduce the PB efficiency and maintain the dosimetry properties. Basing on the acquired data, a simple model of the photobleaching effect on a coil of the investigated fiber is proposed in order to estimate its sensitivity coefficient evolution as a function of the cumulated dose and its fiber length when injecting a certain laser power. Additional studies need to investigate the influence of the temperature and the dose rate on the PB effects since these parameters were fixed during all the reported acquisitions.

Differential regulation of radio-sensitivity/macrophage polarization in intestinal tissue and colorectal cancer for the optimized preoperative radiotherapy

Surgery is the preferred treatment for colorectal cancer, and the preoperative radiotherapy (pre-RT) improves surgical success and postoperative quality of life for patients. However, the therapeutic effect of pre-RT is limited by radiation resistance of tumor and radiation susceptibility of intestine, probably resulting in poor tumor suppression and postoperative anastomotic injury. Herein, we select carboxymethyl chitosan (CMCS) to complex with cerium oxide (CeO2) and calcium ion (Ca2+), obtaining CMCS/CeO2&Ca nano-enema for the optimized pre-RT of colorectal cancer. CMCS/CeO2 and CMCS/CeO2&Ca can mop up various kinds of reactive oxygen species (ROS) and decomposes H2O2 that largely exists in tumor tissue into OH and oxygen (some OH in acidic environment and main oxygen in neutral environment), enhancing free radical clearance in normal tissue and radiation sensitivity of tumor. Meanwhile, RT-induced M1 macrophage in intestinal tissue and the proportion of M2 macrophages in X-rays-treated tumor could be reduced, owing to CMCS/CeO2&Ca-induced change of ROS level. Moreover, CMCS/CeO2&Ca could also promote the proliferation of stem cells in intestine. Therefore, CMCS/CeO2&Ca improves the radio-immunotherapy outcome of colorectal cancer and reduces RT-induced intestinal inflammation/fibrosis, providing an optimal scheme and an effective enema for pre-RT for colorectal cancer.

Different Biocompatibility and Radioprotective Activity of Squid Melanin Nanoparticles on Human Stromal Cells.

Squid ink melanin nanoparticles (NPs) have recently been demonstrated to have a number of bioactivities; however, their biocompatibility has been poorly investigated. In this study, we aimed to evaluate the effects of this NP on stromal cells, including human fibroblasts (hFBs), human umbilical vein endothelial cells (hUVECs), and human umbilical cord-derived mesenchymal stem cells (UCMSCs), and on the development of zebrafish embryos under normal X-ray irradiation conditions. The NPs showed high biocompatibility with low cytotoxicity, no cell senescence induction, and no effect on cell migration in hFBs or cell differentiation in UCMSCs. Nonetheless, this compound prevented cell movement in UCMSCs and significantly suppressed tube formation in hUVECs at a dose of 25 μg/mL. The NPs successfully penetrated the hUVECs but not the other two stromal cell types. The expression levels of functional genes involved in angiogenesis, apoptosis, antioxidant activity, and radiation sensitivity were altered in NPs subjected to hUVECs but were not affected in hFBs and UCMSCs. Melanin NPs significantly rescued cell viability and gene expression in irradiated hFBs and UCMSCs but not in hUVECs. In vivo treatments of zebrafish embryos showed that melanin NPs were nontoxic whether alone or under X-ray irradiation. These findings suggested that nanosized squid ink melanin had biocompatibility with selective stromal cells and was safe for early development.

Targeting Nrf2/PHKG2 axis to enhance radiosensitivity in NSCLC

While ferroptosis shows promise in anti-cancer strategy, the molecular mechanisms behind this process remain poorly understood. Our research aims to highlight the regulation of radiotherapy-induced ferroptosis in non-small cell lung cancer (NSCLC) via the NRF2/PHKG2 axis-mediated mechanism. To identify ferroptosis-associated genes associated with radioresistance in NSCLC, this study employed high-throughput transcriptome sequencing and Lasso risk regression analysis. Clinical samples were analyzed to confirm PHKG2 expression changes before and after radiotherapy. The study further examined ferritinophagy-related factors, intracellular iron levels, mitochondrial function, and ferroptosis in NSCLC cells undergoing radiation exposure to explore the effect of PHKG2 on radiosensitivity or radioresistance. The research also demonstrated the transcriptional inhibition of PHKG2 by NRF2 and created in situ transplantation tumor models of NSCLC to examine the role of NRF2/PHKG2 axis in NSCLC radiosensitivity and resistance in vivo. The Lasso risk regression model that incorporated ferroptosis-associated genes effectively predicted the prognosis of patients with NSCLC. Radiotherapy-sensitive tissues exhibited an increased expression of PHKG2. Overexpression of PHKG2 led to elevated intracellular iron levels by promoting ferritinophagy and increased mitochondrial stress-dependent ferroptosis induced by radiotherapy. PHKG2 transcription repression was achieved through NRF2. The FAGs-Lasso risk regression model can accurately predict the prognosis of NSCLC patients. Targeting Nrf2 upregulates the expression of PHKG2 and reverses radiotherapy resistance in NSCLC by promoting iron autophagy and inducing mitochondrial dysfunction, thereby increasing radiotherapy sensitivity.

Targeting DNA damage repair mechanism by using RAD50-silencing siRNA nanoparticles to enhance radiotherapy in triple negative breast cancer

Radiotherapy (RT) is one of major therapeutic modalities in combating breast cancer. In RT, ionizing radiation is employed to induce DNA double-strand breaks (DSBs) as a primary mechanism that causes cancer cell death. However, the induced DNA damage can also trigger the activation of DNA repair mechanisms, reducing the efficacy of RT treatment. Given the pivotal role of RAD50 protein in the radiation-responsive DNA repair pathways involving DSBs, we developed a novel polymer-lipid based nanoparticle formulation containing RAD50-silencing RNA (RAD50-siRNA-NPs) and evaluated its effect on the RAD50 downregulation as well as cellular and tumoral responses to ionizing radiation using human triple-negative breast cancer as a model. The RAD50-siRNA-NPs successfully preserved the activity of the siRNA, facilitated its internalization by cancer cells via endocytosis, and enabled its lysosomal escape. The nanoparticles significantly reduced RAD50 expression, whereas RT alone strongly increased RAD50 levels at 24 h. Pretreatment with RAD50-siRNA-NPs sensitized the cancer cells to RT with ∼2-fold higher level of initial DNA DSBs as determined by a γH2AX biomarker and a 2.5-fold lower radiation dose to achieve 50 % colony reduction. Intratumoral administration of RAD50-siRNA-NPs led to a remarkable 53 % knockdown in RAD50. The pretreatment with RAD50-siRNA-NPs followed by RT resulted in approximately a 2-fold increase in DNA DSBs, a 4.5-fold increase in cancer cell apoptosis, and 2.5-fold increase in tumor growth inhibition compared to RT alone. The results of this work demonstrate that RAD50 silencing by RAD50-siRNA-NPs can disrupt RT-induced DNA damage repair mechanisms, thereby significantly enhancing the radiation sensitivity of TNBC MDA-MB-231 cells in vitro and in orthotopic tumors as measured by colony forming and tumor regrowth assays, respectively.

Autophagy and radiotherapy in esophageal cancer: modulating treatment sensitivity and overcoming challenges

Abstract Esophageal cancer (ESCA) is one of the most fatal gastrointestinal cancers worldwide. ESCA is often diagnosed in its middle or late stages since the first symptoms are not identifiable. The use of radiotherapy, either alone or in conjunction with surgical intervention and chemotherapy, is essential to achieve a positive prognosis. Radiotherapy is an essential component of treatment for ESCA. Autophagy, a prevalent biological phenomenon, has a twofold impact on the incidence, progression, and treatment response of malignant tumors. This review explores the intricate mechanisms by which autophagy modulates radiation sensitivity in ESCA, including its effects on DNA repair, oxidative stress responses, and apoptosis. We provide a comprehensive analysis of recent advancements in the modulation of autophagy, focusing on the use of autophagy inhibitors and inducers to enhance radiotherapy efficacy. We discuss how autophagy inhibitors such as chloroquine and 3-methyladenine can overcome radiation resistance by blocking autophagic processes, while autophagy inducers like rapamycin can sensitize cancer cells to radiotherapy-induced cell death. Additionally, we examine the potential therapeutic benefits of combining autophagy regulation with existing treatment modalities, offering new strategies to improve patient outcomes. This review highlights the critical role of autophagy in ESCA and underscores the promise of autophagy-targeted therapies in enhancing the effectiveness of radiotherapy, thereby providing a novel avenue for overcoming treatment resistance and improving prognosis in ESCA patients.

Quantitative analysis of dose dependent DNA fragmentation in dry pBR322 plasmid using long read sequencing and Monte Carlo simulations

Exposure to ionizing radiation can induce genetic aberrations via unrepaired DNA strand breaks. To investigate quantitatively the dose–effect relationship at the molecular level, we irradiated dry pBR322 plasmid DNA with 3 MeV protons and assessed fragmentation yields at different radiation doses using long-read sequencing from Oxford Nanopore Technologies. This technology applied to a reference DNA model revealed dose-dependent fragmentation, as evidenced by read length distributions, showing no discernible radiation sensitivity in specific genetic sequences. In addition, we propose a method for directly measuring the single-strand break (SSB) yield. Furthermore, through a comparative study with a collection of previous works on dry DNA irradiation, we show that the irradiation protocol leads to biases in the definition of ionizing sources. We support this scenario by discussing the size distributions of nanopore sequencing reads in the light of Geant4 and Geant4-DNA simulation toolkit predictions. We show that integrating long-read sequencing technologies with advanced Monte Carlo simulations paves a promising path toward advancing our comprehension and prediction of radiation-induced DNA fragmentation.

Study on the sensitizing effect of SM-1 combined with irradiation on head and neck squamous cell carcinoma

Purpose Head and neck squamous cell carcinoma (HNSCC) is globally prevalent with high recurrence, low survival rate, and poor quality of life for patients. Derived from PAC-1, SM-1 can activate procaspase-3 and induce apoptosis in cancer cells to exert anti-tumor effects. However, the inhibitory effect of SM-1 on HNSCC after combination with radiation are unclear. This study aims to investigate the radiosensitizing effect of SM-1 on HNSCC in vitro and in vivo. Methods MTT method was used to detect the effect of SM-1 on the viability of HNSCC cell lines (HONE1, HSC-2, and CAL27). The effects of SM-1 combined with radiation on the survival index of HONE1, HSC-2, and CAL27 cell lines were determined by colony formation assay. Flow cytometry was used to investigate the effects of SM-1 and radiation combination on cell apoptosis and cell cycle, and western blot experiments were performed to detect the expression of apoptosis and cell cycle-related proteins. Finally, a xenograft tumor model of CAL27 was established to evaluate the anti-tumor effect of SM-1 combined with radiation in vivo. Results In vitro, SM-1 effectively inhibited the activity of HNSCC cell lines HONE1, HSC-2, and CAL27 cells, and synergistically showed anti-proliferation activity during combined irradiation. Meanwhile, anti-tumor effect of SM-1 on HNSCC was higher than that of Debio1143, and the radiosensitivity of cells was greatly increased. Flow cytometry and western blot analysis showed that SM-1 induced G2/M phase arrest of head and neck squamous cell carcinoma cells via inhibiting the expression of CyclinB1 and CDC2. Moreover, SM-1 activated caspase-3 activity and up-regulated the cleaved form of PARP1 to induce cell apoptosis. In vivo, SM-1 combined irradiation showed a good anti-tumor effect. Conclusion SM-1 enhances HNSCC cell radiation sensitivity in vitro and in vivo, supporting its potential as a radiosensitizer for clinical trials in combination with radiotherapy.

Aurora Kinase A Inhibition Potentiates Platinum and Radiation Cytotoxicity in Non-Small-Cell Lung Cancer Cells and Induces Expression of Alternative Immune Checkpoints.

Despite major advances in non-small-cell lung cancer (NSCLC) treatment, the five-year survival rates for patients with non-oncogene-driven tumors remain low, necessitating combinatory approaches to improve outcomes. Our prior high-throughput RNAi screening identified Aurora kinase A (AURKA) as a potential key player in cisplatin resistance. In this study, we investigated AURKA's role in platinum and radiation sensitivity in multiple NSCLC cell lines and xenograft mouse models, as well as its effect on immune checkpoints, including PD-L1, B7x, B7-H3, and HHLA2. Of 94 NSCLC patient tumor specimens, 91.5% tested positive for AURKA expression, with 34% showing moderate-to-high levels. AURKA expression was upregulated following cisplatin treatment in NSCLC cell lines PC9 and A549. Both AURKA inhibition by alisertib and inducible AURKA knockdown potentiated the cytotoxic effects of cisplatin and radiation, leading to tumor regression in doxycycline-inducible xenograft mice. Co-treated cells exhibited increased DNA double-strand breaks, apoptosis, and senescence. Additionally, AURKA inhibition alone by alisertib increased PD-L1 and B7-H3 expression. In conclusion, our study demonstrates that AURKA inhibition enhances the efficacy of platinum-based chemotherapy in NSCLC cells and modulates the expression of multiple immune checkpoints. Therefore, combinatory regimens with AURKA inhibitors should be strategically designed and further studied within the evolving landscape of chemo-immunotherapy.

NAD+ Metabolism Reprogramming Mediates Irradiation-Induced Immunosuppressive Polarization of Macrophages

Purposeradiotherapy stands as an important complementary treatment for head and neck squamous cell carcinoma (HNSCC), yet it does not invariably result in complete tumor regression. The infiltration of immunosuppressive macrophages is believed to mediate the radiotherapy resistance, which mechanism remains largely unexplored. This study aimed to elucidate the role of immunosuppressive macrophages during radiotherapy and the associated underlying mechanisms. Materials and MethodsMale C3H mice bearing syngeneic SCC-VII tumor were received irradiation (2 × 8Gy). The impact of irradiation on tumor-infiltrating macrophages were assessed. Bone marrow derived macrophages were evaluated in differentiation, proliferation, migration, and inflammatory cytokines after treatment of irradiated tumor culture medium (irCM) and irradiated tumor derived extracellular vesicles (irTEVs). A comprehensive metabolomics profiling of the irTEVs was conducted using liquid chromatography-mass spectrometry, while key metabolites were investigated the mechanism in macrophage in vitro and in vivo. ResultsRadiotherapy on SCC-VII syngeneic graft tumors increased polarization of both M1 and M2 macrophages in tumor microenvironment and drove infiltrated macrophages towards an immunosuppressive phenotype. Irradiation-induced polarization and immunosuppression of macrophages were dependent on irTEVs which delivered an increased amount of nicotinamide (NAM) to macrophages. NAM directly bound to the NF-κB transcriptional activity regulator USP7, through which NAM reduced translocation of NF-κB into the nucleus, thereby decreasing the release of cytokines IL6 and IL8. Increased enzyme activity of nicotinamide phosphoribosyl transferase (NAMPT) which is the rate-limiting enzyme of NAD+ metabolism, contributed to the irradiation-induced accumulation levels of NAM in irradiated HNSCC and irTEVs. Inhibition of NAMPT decreased NAM levels in irTEVs and increased radiotherapy sensitivity through alleviating immunosuppressive function of macrophages. ConclusionsRadiotherapy could induce NAD+ metabolic reprogramming of HNSCC cells, which regulate macrophage towards an immunosuppressive phenotype. Pharmacological targeting NAD+ metabolism might be a promising strategy for radiotherapy sensitization of HNSCC.

Overexpression of ESYT3 improves radioimmune responses through activating cGAS-STING pathway in lung adenocarcinoma

BackgroundRadiotherapy can modulate systemic antitumor immunity, while immune status in the tumor microenvironment also influences the efficacy of radiotherapy, but relevant molecular mechanisms are poorly understood in lung adenocarcinoma (LUAD).MethodsIn this study, we innovatively proposed a radiotherapy response classification for LUAD, and discovered ESYT3 served as a tumor suppressor and radioimmune response sensitizer. ESYT3 expression was measured both in radioresistant and radiosensitive LUAD tissues and cells. The influence of ESYT3 on radiotherapy sensitivity and resistance was then investigated. Interaction between ESYT3 and STING was evaluated through multiple immunofluorescent staining and coimmunoprecipitation, and downstream molecules were further analyzed. In vivo models were constructed to assess the combination treatment efficacy of ESYT3 overexpression with radiotherapy.ResultsWe found that radioresistant subtype presented immunosuppressive state and activation of DNA damage repair pathways than radiosensitive subtype. ESYT3 expression was remarkably attenuated both in radioresistant LUAD tissues and cells. Clinically, low ESYT3 expression was linked with radioresistance. Overexpression of ESYT3 enabled to alleviate radioresistance, and sensitize LUAD cells to DNA damage induced by irradiation. Mechanically, ESYT3 directly interacted with STING, and activated cGAS-STING signaling, subsequently increasing the generation of type I IFNs as well as downstream chemokines CCL5 and CXCL10, thus improving radioimmune responses. The combination treatment of ESYT3 overexpression with radiotherapy had a synergistic anticancer effect in vitro and in vivo.ConclusionsIn summary, low ESYT3 expression confers resistance to radiotherapy in LUAD, and its overexpression can improve radioimmune responses through activating cGAS-STING-dependent pathway, thus providing an alternative combination therapeutic strategy for LUAD patients.

A Self-Catalytic NO/O2 Gas-Releasing Nanozyme for Radiotherapy Sensitization through Vascular Normalization and Hypoxia Relief.

Radiotherapy (RT), essential for treating various cancers, faces challenges from tumor hypoxia, which induces radioresistance. A tumor-targeted "prosthetic-Arginine" coassembled nanozyme system, engineered to catalytically generate nitric oxide (NO) and oxygen (O2) in the tumor microenvironment (TME), overcoming hypoxia and enhancing radiosensitivity is presented. This system integrates the prosthetic heme of nitric oxide synthase (NOS) and catalase (CAT) with NO-donating Fmoc-protected Arginine and Ru3+ ions, creating HRRu nanozymes that merge NOS and CAT functionalities. Surface modification with human heavy chain ferritin (HFn) improves the targeting ability of nanozymes (HRRu-HFn) to tumor tissues. In the TME, strategic arginine incorporation within the nanozyme allows autonomous O2 and NO release, triggered by endogenous hydrogen peroxide, elevating NO and O2 levels to normalize vasculature and improve blood perfusion, thus mitigating hypoxia. Employing the intrinsic O2-transporting ability of heme, HRRu-HFn nanozymes also deliver O2 directly to the tumor site. Utilizing esophageal squamous cell carcinoma as a tumor model, the studies reveal that the synergistic functions of NO and O2 production, alongside targeted delivery, enable the HRRu-HFn nanozymes to combat tumor hypoxia and potentiate radiotherapy. This HRRu-HFn nanozyme based approach holds the potential to reduce the radiation dose required and minimize side effects associated with conventional radiotherapy.