Enhanced Radiation Sensitivity Research Articles

Self-assembling chemodrug fiber-hydrogel for transarterial chemoembolization and radiotherapy-enhanced antitumor immunity.

Hydrogel, as a promising embolic material for hepatocellular carcinoma (HCC), may fully embolize both major vessels and peripheral microvessels. A self-assembling hydrogel composed of chemotherapeutic drugs offers significant clinical benefits without carrier introduction. Herein, we developed a sustained drug-releasing complex hydrogel (RKT@gel), which was fabricated by the self-assembly of raltitrexed chemotherapeutic drugs (R@gel), along with the incorporation of kaempferol and tantalum nanoparticles (Ta NPs). Kaempferol enhances the mechanical strength of R@gel and inhibits hypoxia-induced angiogenesis post-embolization, improving embolization effectiveness. In addition to enabling X-ray-guided transarterial chemoembolization (TACE), Ta NPs enhance radiation sensitivity. These synergistic effects of RKT@gel not only significantly induce immunogenic cell death, thereby enhancing the activation of dendritic cells, but also activate major histocompatibility complex class I (MHC-I)-mediated antitumor immune recognition and cytotoxicity. In vivo, RKT@gel achieves enhanced tumor deposition and sustained drug release, effectively suppressing tumor progression. Additionally, when combined with radiotherapy, RKT@gel achieves efficient antitumor immunoactivation. Overall, this versatile composite hydrogel not only achieves effective embolization therapy but also substantially triggers antitumor immune responses with good biocompatibility. This multifunctional design provides a TACE-based multidisciplinary strategy for HCC.

Long-Term Therapeutic Effects of 225Ac-DOTA-E[c(RGDfK)]2 Induced by Radiosensitization via G2/M Arrest in Pancreatic Ductal Adenocarcinoma.

Background: Alpha radionuclide therapy has emerged as a promising novel strategy for cancer treatment; however, the therapeutic potential of 225Ac-labeled peptides in pancreatic cancer remains uninvestigated. Methods: In the cytotoxicity study, tumor cells were incubated with 225Ac-DOTA-RGD2. DNA damage responses (γH2AX and 53BP1) were detected using flowcytometry or immunohistochemistry analysis. Biodistribution and therapeutic studies were carried out in BxPC-3-bearing mice. Results: 225Ac-DOTA-RGD2 demonstrated potent cytotoxicity against cells expressing αvβ3 or αvβ6 integrins and induced G2/M arrest and γH2AX expression as a marker of double-stranded DNA breaks. 225Ac-DOTA-RGD2 (20, 40, 65, or 90 kBq) showed favorable pharmacokinetics and remarkable tumor growth inhibition without severe side effects in the BxPC-3 mouse model. In vitro studies revealed that 5 and 10 kBq/mL of 225Ac-DOTA-RGD2 swiftly induced G2/M arrest and elevated γH2AX expression. Furthermore, to clarify the mechanism of successful tumor growth inhibition for a long duration in vivo, we investigated whether short-term high radiation exposure enhances radiation sensitivity. Initially, a 4 h induction treatment with 5 and 10 kBq/mL of 225Ac-DOTA-RGD2 enhanced both cytotoxicity and γH2AX expression with 0.5 kBq/mL of 225Ac-DOTA-RGD2 compared to a treatment with only 0.5 kBq/mL of 225Ac-DOTA-RGD2. Meanwhile, the γH2AX expression induced by 5 or 10 kBq/mL of 225Ac-DOTA-RGD2 alone decreased over time. Conclusions: These findings highlight the potential of using 225Ac-DOTA-RGD2 in the treatment of intractable pancreatic cancers, as its ability to induce G2/M cell cycle arrest enhances radiosensitization, resulting in notable growth inhibition.

Targeting ATM enhances radiation sensitivity of colorectal cancer by potentiating radiation-induced cell death and antitumor immunity.

The efficacy of radiotherapy in colorectal cancer (CRC) is often limited by radiation resistance. Ataxia telangiectasia mutated (ATM) is well known for its role in repairing double-strand DNA breaks within the DNA damage response (DDR) pathway. However, whether ATM mediates other mechanisms contributing to radiation resistance remains insufficiently investigated. This study investigates how targeting ATM enhances CRC radiation sensitivity and evaluates combination strategies to improve radiotherapy outcomes. Clinical specimens were analyzed to correlate ATM activation with radiotherapy response. Functional assays, including EdU, cell viability, clonogenic survival, and apoptosis assays, were used to assess the impact of ATM inhibition on radiation sensitivity. Mechanistic insights were gained through RNA-seq, RT-qPCR, western blotting, ELISA, immunofluorescence, flow cytometry, ChIP-qPCR, and co-immunoprecipitation. In vivo efficacy was evaluated using subcutaneous tumor models in nude, BALB/c, and C57BL/6J mice. High ATM phosphorylation levels correlated with poor radiotherapy response in CRC patients. ATM inhibition enhanced radiation sensitivity in both in vitro and in vivo models. Mechanistically, ATM inhibition increased radiation-induced ROS accumulation and mitochondrial damage, leading to the release of mitochondrial DNA (mtDNA) into the cytosol and activation of the STING-type I interferon pathway. This enhanced CD8+ T cell infiltration and boosted antitumor immunity. Additionally, ATM inhibition partially alleviated the radiation-induced upregulation of PD-L1, likely through the ATM/NEMO/NF-κB pathway. Notably, triple therapy combining radiotherapy, an ATM inhibitor, and anti-PD-L1 achieved superior tumor control and remission in mouse models, including large, treatment-resistant tumors. Targeting ATM enhances radiation-induced tumor cell death and boosts antitumor immune responses, offering a promising strategy to overcome CRC radiation resistance. The synergy of radiotherapy, ATM inhibitior, and immune checkpoint blockade highlights a novel therapeutic approach for CRC management.

CNSC-49. ELUCIDATING THERAPEUTIC POTENTIAL OF USP1 INHIBITION IN DIFFUSE MIDLINE GLIOMAS

Abstract Diffuse midline gliomas (DMGs) are aggressive childhood brain tumors with the H3K27M mutation in the H3F3A or H3C2 gene. Despite treatment advances, radiotherapy is the only viable option, but 99% of patients die within 1.5-2 years. Therefore, there is an urgent need to identify potential novel therapeutic targets for the treatment of DMGs. Ubiquitin-specific protease 1 (USP1) is a key deubiquitinating enzyme involved in genome integrity, cell cycle regulation, and cell homeostasis. USP1 is overexpressed in various cancers, including gliomas, is linked to poor prognosis. It promotes glioma stem cell (GSC) self-renewal and radio-resistance by regulating ID1 and CHEK1. Our recent findings show that ID1 is crucial for DMG invasion and migration. Inhibiting USP1 suppresses malignant growth, enhances radiation sensitivity, and improves chemotherapy response, highlighting its potential for combined therapies. However, USP1’s role in DMGs and its feasibility as a therapeutic target remain poorly understood. In this study, we investigated USP1 in DMGs for the first time. RNA sequencing revealed high USP1 expression in DMG patient samples and cell lines, directly linked to the H3K27M mutation. Correcting this mutation reduced USP1 expression in DMG cell lines. Pharmacologic inhibition of USP1 with the specific inhibitor SJB3-019A significantly reduced DMG cell proliferation, triggered apoptosis, and altered cell cycle profile. SJB3-019A-mediated USP1 inhibition decreases migration and invasion in multiple patient-derived DMG cell lines. Additional in vitro experiments revealed that USP1 inhibition leads to a significant decrease in the expression of ID1 and pAKT, suggesting the ID1/AKT pathway as a potential mechanism underlying the observed effects. H3K27M-mediated activation of USP1 in DMG is a promising therapeutic target, with inhibition by SJB3-019A reducing tumor aggressiveness by inhibiting invasion and migration. We will next assess SJB3-019A’s efficacy in vivo using genetically engineered isogenic mouse models (GEMM) with DNp53/PDGFRA/H3.3K27M (PPK) alterations and evaluate USP1 inhibition combined with radiation therapy as a potential radiosensitizer in DMGs.

PACAP38 synergizes with irradiation to suppress the proliferation of multiple cancer cells via regulating SOX6/Wnt/β-catenin signaling.

Pituitary adenylate cyclase-activating polypeptide (PACAP) 38 is an endogenous neuropeptide with diverse functions, notably its critical role in inhibiting tumor proliferation. Radiotherapy is an important step in the standard treatment modality of many tumors. Combining radiotherapy with therapeutic agents represents a new and promising trend aimed at enhancing radiation sensitivity and improving tumor treatment efficacy. However, the efficacy of PACAP38 combined with radiotherapy on tumors has not yet been studied. This study aimed to investigate the impact of PACAP38, both independently and in combination with irradiation, on glioma and breast cancer cells, while elucidating the underlying mechanisms involved. We investigated the impact of PACAP38 independently and combined it with irradiation on glioma and breast cancer cells in vitro through cell counting kit-8, clonogenic formation, Edu assays, and in vivo through a xenograft tumor model. We further explored the molecular mechanisms underlying the inhibitory effects of PACAP38 on tumors using RNA sequencing, western blotting assay, immunohistochemistry, and immunofluorescence analysis. Further investigation of gene function and the downstream mechanism was carried out through small interfering RNA and overexpression lentivirus targeting the SRY-related high-mobility group box 6 (SOX6) gene and western blotting assay. Our findings revealed that PACAP38 could effectively synergize with radiation to suppress the proliferation of glioma and breast cancer cells in vivo and in vitro. Molecular studies revealed that the inhibitory effect of PACAP38 on tumor cell proliferation was mediated by upregulating SOX6 protein expression through histone acetylation, thereby inhibiting the Wnt-β-catenin signaling pathway. PACAP38 synergizes with irradiation to suppress the proliferation of multiple cancer cells via regulating SOX6/Wnt/β-catenin signaling. This combination may represent a promising therapeutic strategy for cancer treatment, potentially improving outcomes for patients undergoing radiotherapy.

Comment on "gemcitabine, PI3kinase-Akt pathway inhibition and radiation in human glioma cell lines" by M.S. Elnaggar et al.1.

The combination of gemcitabine, PI3K-Akt pathway inhibitors, and radiation in human glioma cell lines shows potential to enhance radiation sensitivity in aggressive brain tumors. Inhibiting the overactive PI3K-Akt pathway may increase tumor vulnerability to treatment. However, variability in responses among different glioma cell lines highlights the need for personalized approaches. Future research should focus on identifying biomarkers to tailor treatment for individual patients. Additionally, addressing safety concerns and the challenges of translating preclinical findings into clinical practice is crucial. Further studies should explore the therapy's molecular mechanisms and evaluate its clinical potential.

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.

Enhanced radiation sensitivity, decreased DNA damage repair, and differentiation defects in airway stem cells derived from patients with chronic obstructive pulmonary disease.

Radiation therapy (RT) is a common treatment for lung cancer. Still, it can lead to irreversible loss of pulmonary function and a significant reduction in quality of life for one-third of patients. Preexisting comorbidities, such as chronic obstructive pulmonary disease (COPD), are frequent in patients with lung cancer and further increase the risk of complications. Because lung stem cells are crucial for the regeneration of lung tissue following injury, we hypothesized that airway stem cells from patients with COPD with lung cancer might contribute to increased radiation sensitivity. We used the air-liquid interface model, a three-dimensional (3D) culture system, to compare the radiation response of primary human airway stem cells from healthy and patients with COPD. We found that COPD-derived airway stem cells, compared to healthy airway stem cell cultures, exhibited disproportionate pathological mucociliary differentiation, aberrant cell cycle checkpoints, residual DNA damage, reduced survival of stem cells and self-renewal, and terminally differentiated cells post-irradiation, which could be reversed by blocking the Notch pathway using small-molecule γ-secretase inhibitors. Our findings shed light on the mechanisms underlying the increased radiation sensitivity of COPD and suggest that airway stem cells reflect part of the pathological remodeling seen in lung tissue from patients with lung cancer receiving thoracic RT.

The COP9 signalosome stabilized MALT1 promotes Non-Small Cell Lung Cancer progression through activation of NF-κB pathway

MALT1 has been implicated as an upstream regulator of NF-κB signaling in immune cells and tumors. This study determined the regulatory mechanisms and biological functions of MALT1 in non-small cell lung cancer (NSCLC). In cell culture and orthotopic xenograft models, MALT1 suppression via gene expression interference or protein activity inhibition significantly impaired malignant phenotypes and enhanced radiation sensitivity of NSCLC cells. CSN5, the core subunit of COP9 signalosome, was firstly verified to stabilize MALT1 via disturbing the interaction with E3 ligase FBXO3. Loss of FBXO3 in NSCLC cells reduced MALT1 ubiquitination and promoted its accumulation, which was reversed by CSN5 interference. An association between CSN5/FBXO3/MALT1 regulatory axis and poor prognosis in NSCLC patients was identified. Our findings revealed the detail mechanism of continuous MALT1 activation in NF-κB signaling, highlighting its significance as predictor and potential therapeutic target in NSCLC.Graphical

BET bromodomain inhibition potentiates radiosensitivity in models of H3K27-altered diffuse midline glioma.

Diffuse midline glioma (DMG) H3K27-altered is one of the most malignant childhood cancers. Radiation therapy remains the only effective treatment yet provides a 5-year survival rate of only 1%. Several clinical trials have attempted to enhance radiation antitumor activity using radiosensitizing agents, although none have been successful. Given this, there is a critical need for identifying effective therapeutics to enhance radiation sensitivity for the treatment of DMG. Using high-throughput radiosensitivity screening, we identified bromo- and extraterminal domain (BET) protein inhibitors as potent radiosensitizers in DMG cells. Genetic and pharmacologic inhibition of BET bromodomain activity reduced DMG cell proliferation and enhanced radiation-induced DNA damage by inhibiting DNA repair pathways. RNA-Seq and the CUT&RUN (cleavage under targets and release using nuclease) analysis showed that BET bromodomain inhibitors regulated the expression of DNA repair genes mediated by H3K27 acetylation at enhancers. BET bromodomain inhibitors enhanced DMG radiation response in patient-derived xenografts as well as genetically engineered mouse models. Together, our results highlight BET bromodomain inhibitors as potential radiosensitizer and provide a rationale for developing combination therapy with radiation for the treatment of DMG.

Enhancing starch functionality through synergistic modification via sequential treatments with cold plasma and electron beam irradiation

The impact of dual sequential modifications using radio-frequency (RF) plasma and electron beam irradiation (EBI) on starch properties was investigated and compared with single treatments within an irradiation dose range of 5–20 kGy. Regardless of sequence, dual treatments synergistically affected starch properties, increasing acidity, solubility, and paste clarity, while decreasing rheological features with increasing irradiation dose. The molecular weight distribution was also synergistically influenced. Amylopectin distribution broadened particularly below 10 kGy. Amylose narrowed its distribution across all irradiation doses. This was due to dominating EBI-induced degradation and molecular rearrangements from RF plasma. With the highest average radiation-chemical yield (G) and degradation rate constant (k) of (2.12 ± 0.14) × 10−6 mol·J−1 and (3.43 ± 0.23) × 10−4 kGy−1, respectively, upon RF plasma pre-treatment, amylose underwent random chain scission. In comparison to single treatments, dual modification caused minor alterations in spectral characteristics and crystal short-range order structure, along with increased granule aggregation and surface irregularities. The synergistic effect was dose-dependent, significant up to 10 kGy, irrespective of treatment sequence. The highest synergistic ratio was observed when RF plasma preceded irradiation, demonstrating the superior efficiency of plasma pre-treatment in combination with EBI. This synergy has the potential to lower costs and extend starch's technological uses by enhancing radiation sensitivity and reducing the irradiation dose.

LILRB2 inhibition enhances radiation sensitivity in non-small cell lung cancer by attenuating radiation-induced senescence

Radiotherapy (RT) in non-small cell lung cancer (NSCLC) triggers cellular senescence, complicating tumor microenvironments and affecting treatment outcomes. This study examines the role of lymphocyte immunoglobulin-like receptor B2 (LILRB2) in modulating RT-induced senescence and radiosensitivity in NSCLC. Through methodologies including irradiation, lentivirus transfection, and various molecular assays, we assessed LILRB2’s expression and its impact on cellular senescence levels and tumor cell behaviors. Our findings reveal that RT upregulates LILRB2, facilitating senescence and a senescence-associated secretory phenotype (SASP), which in turn enhances tumor proliferation and resistance to radiation. Importantly, LILRB2 silencing attenuates these effects by inhibiting the JAK2/STAT3 pathway, significantly increasing radiosensitivity in NSCLC models. Clinical data correlate high LILRB2 expression with reduced RT response and poorer prognosis, suggesting LILRB2’s pivotal role in RT-induced senescence and its potential as a therapeutic target to improve NSCLC radiosensitivity.

Post-Irradiation Behavior of Colored PVA-Based Films Containing Ag Nanoparticles as Radiation Detectors/Exposure Indicators.

Ionizing radiation covers a broad spectrum of applications. Since radioactive/radiation pollution is directly related to radiation risk, radiation levels should be strictly controlled. Different detection methods can be applied for radiation registration and monitoring. In this paper, radiation-induced variations in the optical properties of silver-enriched PVA-based hydrogel films with and without azo dye (Toluidine blue O, TBO, and Methyl red, MR) additives were investigated, and the feasibility of these free-standing films to serve as radiation detectors/exposure indicators was assessed. AgNO3 admixed with PVA gel was used as a source for the radiation-induced synthesis of silver nanoparticles (AgNPs) in irradiated gel films. Three types of sensors were prepared: silver-enriched PVA films containing a small amount of glycerol (AgPVAGly); silver-enriched PVA films with toluidine blue adducts (AgPVAGlyTBO); and silver-enriched PVA films with methyl red additives (AgPVAGlyMR). The selection of TBO and MR was based on their sensitivity to irradiation. The irradiation of the samples was performed in TrueBeam2.1 (VARIAN) using 6 MeV photons. Different doses up to 10 Gy were delivered to the films. The sensitivity of the films was assessed by analyzing the characteristic UV-Vis absorbance peaks on the same day as irradiation and 7, 30, 45, 90, and 180 days after irradiation. It was found that the addition of azo dyes led to an enhanced radiation sensitivity of the AgNPs containing films (0.6 Gy-1 for AgPVAGlyTBO and 0.4 Gy-1 for AgPVAGlyMR) irradiated with <2 Gy doses, indicating their applicability as low-dose exposure indicators. The irradiated films were less sensitive to higher doses. Almost no dose fading was detected between the 7th and 45th day after irradiation. Based on the obtained results, competing AgNP formation and color-bleaching effects in the AgPVAGly films with dye additives are discussed.

Abstract 3585: DNA-PK inhibition to enhance radiation sensitivity in metastatic pancreatic neuroendocrine cancer

Abstract Gastroenteropancreatic (GEP) neuroendocrine tumors (NETs) are neoplasms originating from the gastrointestinal track and pancreas. Unfortunately, most patients at the time of diagnosis have extensive metastatic disease and are not candidates for curative surgical resection of metastatic tumors. In such cases, targeted radiation therapy (RT) can slow the progression of metastatic disease, but eventually tumors develop resistance to radiation therapy. In this study, we examined whether DNA-PK inhibition could sensitize pancreatic NETs to radiation therapy and enhance the radiation therapy effect in a preclinical model of pNET metastasis. Methods. We used 96-well clonogenic assays to evaluate the efficacy of the DNA-PK inhibitor peposertib in combination with RT in vitro in QGP-1 and BON pancreatic NET cell lines. Double-strand break-induced DNA repair was visualized with confocal laser scanning microscopy using γ-H2AX immunofluorescence after peposertib treatment alone or in combination with RT. Western blot analysis was used to confirm inhibition of DNA-PKcs (pDNA-PKcs S2056) combination RT. The efficacy of peposertib in combination with RT was evaluated in QGP-1 and BON human xenograft models in athymic nude mice and a BON preclinical lung metastasis model. Results. Clonogenic assays demonstrated absence of cytotoxicity from peposertib alone at doses below 1000 nM and a strong radiosensitizing effect at 200 nM in both QGP-1 and BON cell lines. Pretreatment with peposertib or treatment within 2 h after RT suppressed colony formation; treatment at later timepoints did not enhance radiotherapy. Immunofluorescence analysis revealed high numbers of γH2AX foci with peposertib therapy alone at 96 h or when given 2 h after RT. Western blot analysis confirmed inhibition of DNA-PK Ser2056 after RT in combination with peposertib. DNA-PK inhibition in combination with RT led to remarkable repression of pNET growth both in subcutaneous xenografts (&amp;gt;90%) and in the preclinical lung metastasis model (&amp;gt;90%). Conclusions. Our results showed several advantages of targeting DNA-PK to enhance radiation sensitivity in high-grade pNETs: (1) DNA-PK inhibition alone disrupts DNA damage response in pNETs as demonstrated by strong H2AX phosphorylation. (2) DNA-PK inhibition is most effective at enhancing radiotherapy either right before or after radiation therapy administration. This demonstrates that extended DNA-PK inhibition is not necessary to achieve marked responses during pNET radiotherapy. (3) DNA-PK inhibition 30 min before radiation therapy is sufficient to greatly reduce pNET tumor growth or metastasis progression in pNET preclinical models. In summary, selective DNA-PK inhibition provides a potent therapeutic strategy for disruption of non-homologous end joining DNA double-strand break repair and may offer a novel therapeutic approach in advanced NET radiotherapy. Citation Format: Piotr G. Rychahou, Aman Chauhan, Zeta Chow, Tadahide Izumi, Quan Chen, Eun Y. Lee, Dana Napier, Lowell Brian Anthony, Michael J. Cavnar, Courtney M. Townsend, B. Mark Evers. DNA-PK inhibition to enhance radiation sensitivity in metastatic pancreatic neuroendocrine cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3585.

Abstract IA006: Multifaceted effects of DNA damage response inhibitors on radiation responses of glioblastoma and the normal brain

Abstract PARP inhibitors (PARPi) and ATM inhibitors (ATMi) enhance radiation sensitivity in multiple cancer models, both in vitro and in vivo. Our observation that the radiosensitizing properties of PARPi are most pronounced in rapidly proliferating cells is reflected in early phase clinical trial data showing exacerbation of acute radiation toxicity in rapidly proliferating tissues such as oropharyngeal and esophageal mucosa. Lack of radiosensitization in late responding, slowly proliferating normal tissues indicates that PARPi may be more effectively combined with radiation therapy (RT) in patients with brain tumors. ATMi are much more potent radiosensitizers than PARPi but less is known about their impact on normal tissue toxicity since they have only recently progressed to the clinic, although preclinical in vivo data are encouraging. We are evaluating the oral PARPi olaparib and the oral ATMi AZD1390 in combination with RT +/- temozolomide (TMZ) in the treatment of glioblastoma (GBM), the most prevalent and most aggressive primary brain tumor. Patients with GBM experience very poor outcomes in terms of both median survival (c.1 year) and neurocognitive decline, which is caused primarily by RT. Early phase testing of the olaparib-RT combination is underway in three populations of patients with newly diagnosed GBM. Patients aged &amp;gt;65 with MGMT unmethylated GBM are being recruited to a randomized, placebo-controlled phase II study (PARADIGM, ISRCTN52658296) after a phase I dose escalation study showed that olaparib (200 mg twice daily) was extremely well tolerated when combined with brain irradiation (40 Gray in 15#). Good performance status patients aged under 70 are being recruited to PARADIGM-2 (ISRCTN51253312) which comprises two parallel phase I dose escalation studies: patients with MGMT unmethylated tumors are receiving daily olaparib with RT (60 Gy in 30#) without TMZ, while patients with MGMT methylated tumors are receiving intermittent olaparib with standard chemoradiation. AZD1390 is being evaluated in a first-in-human phase I dose escalation study (NCT03423628) in combination with re-irradiation (35 Gy in 10#) in patients with recurrent GBM, and with first-line radical radiotherapy (60 Gy in 30#) in patients with newly diagnosed, MGMT unmethylated GBM. In parallel, we are undertaking preclinical studies to investigate the impact of PARPi and ATMi on RT induced neurotoxicity. In vivo imaging studies support the emerging concept that RT induced neuroinflammation is important in the pathogenesis of neurotoxicity, and we have generated preliminary behavioral data indicating that both PARPi and ATMi can alleviate the neurotoxic effects of RT. Ongoing experiments are defining the roles of microglia, astrocytes and neurogenesis in this phenomenon. We will present these diverse datasets in the context of our hypothesis that combining PARPi or ATMi with RT has potential to improve outcomes for GBM patients by enhancing tumor control while simultaneously suppressing neuroinflammation and alleviating RT related neurocognitive decline. Citation Format: Anthony J. Chalmers. Multifaceted effects of DNA damage response inhibitors on radiation responses of glioblastoma and the normal brain [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: DNA Damage Repair: From Basic Science to Future Clinical Application; 2024 Jan 9-11; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2024;84(1 Suppl):Abstract nr IA006.

CHAC1 promotes cell ferroptosis and enhances radiation sensitivity in thyroid carcinoma.

ChaC glutathione-specific γ-glutamylcyclotransferase 1 (CHAC1) is involved in intracellular glutathione depletion, ferroptosis, and tumorigenesis. The functional role of CHAC1 expression in thyroid carcinoma has not yet been established. The present study aimed to investigate the impact and mechanisms of CHAC1 on ferroptosis and radiation sensitivity in thyroid carcinoma. CHAC1 expression was examined in tumor tissue specimens and microarrays and thyroid carcinoma cell lines. CHAC1 was silenced or overexpressed by lentivirus transfection in thyroid carcinoma cells. Cell viability and lipid ROS levels were evaluated by Cell Counting Kit-8 and flow cytometry, respectively. The effect of CHAC1 on tumor growth in vivo was also measured. Ferroptosis-related proteins were measured by western blotting. CHAC1 expression was decreased in patients with thyroid carcinoma, and overexpression of CHAC1 suppressed cell viability of BCPAP cells and tumor growth in xenografted nude mice. Exposure to Ferrostatin-1, a ferroptosis inhibitor, significantly attenuated the inhibitory effects of CHAC1 overexpression on cell viability. In CHAC1-overexpressing BCPAP cells, ferroptosis was induced as indicated by increased lipid ROS production and PTGS2 expression. Knocking down of CHAC1 in K1 cells significantly induced cell viability, reduced lipid ROS production and PTGS2 expression, and enhanced GPX4 expression. Such effects were attenuated by RSL3, a ferroptosis inducer. Furthermore, we showed that CHAC1 overexpression enhanced radiation sensitivity in BCPAP cells as indicated by decreased cell viability, while CHAC1 knockdown had reversed effects in K1 cells as indicated by increased cell viability. Taken together, CHAC1 overexpression promoted ferroptosis and enhanced radiation sensitivity in thyroid carcinoma.

Revolutionizing head and neck squamous cell carcinoma treatment with nanomedicine in the era of immunotherapy.

Head and neck squamous cell carcinoma (HNSCC) is a prevalent malignant tumor globally. Despite advancements in treatment methods, the overall survival rate remains low due to limitations such as poor targeting and low bioavailability, which result in the limited efficacy of traditional drug therapies. Nanomedicine is considered to be a promising strategy in tumor therapy, offering the potential for maximal anti-tumor effects. Nanocarriers can overcome biological barriers, enhance drug delivery efficiency to targeted sites, and minimize damage to normal tissues. Currently, various nano-carriers for drug delivery have been developed to construct new nanomedicine. This review aims to provide an overview of the current status of HNSCC treatment and the necessity of nanomedicine in improving treatment outcomes. Moreover, it delves into the research progress of nanomedicine in HNSCC treatment, with a focus on enhancing radiation sensitivity, improving the efficacy of tumor immunotherapy, effectively delivering chemotherapy drugs, and utilizing small molecule inhibitors. Finally, this article discussed the challenges and prospects of applying nanomedicine in cancer treatment.

NRF2 connects Src tyrosine kinase to ferroptosis resistance in glioblastoma.

Glioblastoma is a severe brain tumor characterized by an extremely poor survival rate of patients. Glioblastoma cancer cells escape to standard therapeutic protocols consisting of a combination of ionizing radiation and temozolomide alkylating drugs that trigger DNA damage by rewiring of signaling pathways. In recent years, the up-regulation of factors that counteract ferroptosis has been highlighted as a major driver of cancer resistance to ionizing radiation, although the molecular connection between the activation of oncogenic signaling and the modulation of ferroptosis has not been clarified yet. Here, we provide the first evidence for a molecular connection between the constitutive activation of tyrosine kinases and resistance to ferroptosis. Src tyrosine kinase, a central hub on which deregulated receptor tyrosine kinase signaling converge in cancer, leads to the stabilization and activation of NRF2 pathway, thus promoting resistance to ionizing radiation-induced ferroptosis. These data suggest that the up-regulation of the Src-NRF2 axis may represent a vulnerability for combined strategies that, by targeting ferroptosis resistance, enhance radiation sensitivity in glioblastoma.

Luteolin inhibits angiogenesis and enhances radiotherapy sensitivity of laryngeal cancer via downregulating Integrin β1

AimTo demonstrate the role and mechanism of luteolin in radio-sensitization and angiogenesis of laryngeal cancer. MethodsFirstly, we analyzed the cytotoxicity of Luteolin and radiation sensitive cytotoxicity through CCK8, and selected subsequent radiation doses and Luteolin concentrations. Next, we further analyzed the effects of Luteolin on radiation sensitivity and neovascularization of laryngeal cancer, and conducted CCK8, plate cloning, and angiogenesis experiments, respectively. At the same time, the effects of individual treatment and combination treatment on the expression of Integrin β1 and VEGFA were analyzed through immunofluorescence analysis. We also analyzed the regulation of Integrin β1 protein expression by Luteolin through Western blot. To investigate the mechanism of Integrin β1, we transfected overexpressed and silenced Integrin β1 vectors and analyzed the role of Integrin β1 in Luteolin enhancing radiation sensitivity of laryngeal cancer by repeating the above experiments. We have also constructed an in vivo subcutaneous tumor transplantation model to further validate the cell experimental results. The expression of Integrin, KI67, VEGFA, and CD31 was analyzed through Western blot and immunohistochemistry experiments. ResultsRadiation inhibited cell proliferation and decreased Integrin β1 expression, and increased the radiosensitivity through inhibiting cell proliferation, and inhibit angiogenesis during radiation. Overexpression of Integrin β1 weakened radiotherapy sensitivity on the basis of cells treated with combined administration. Integrin β1 is considered as the downstream molecule of luteolin, participating in radiosensitivity of luteolin to FaDu cells. Animal experiments also demonstrated that luteolin strengthened tumor suppression and anti-angiogenesis during radiation via Integrin β1. ConclusionIn summary, our results manifested that radio-sensitivity effect of luteolin depended on downregulating Integrin β1 in laryngocarcinoma.

Gamma Secretase Inhibition Sensitizes Pancreatic Adenocarcinoma Tumors to RT In Vivo

Pancreatic adenocarcinoma (PDAC) is an extremely aggressive cancer that lacks curative treatment options. Almost half of patients present with unresectable disease limiting treatment to non-curative options. Patients treated with neoadjuvant radiation therapy (RT) exhibit increases in fibrosis and epithelial-to-mesenchymal transition (EMT). ADAM10, an extracellular sheddase, can stimulate stromal fibrosis, EMT, and radioresistance. ADAM10 also mediates EMT through Notch signaling by cleaving its extracellular domain. Further cleavage by gamma secretase produces the Notch intracellular domain (NICD), which translocates to the nucleus and activates downstream transcriptional targets. Here, we explore whether inhibition of Notch cleavage by gamma secretase radiosensitizes PDAC tumors. Bilateral flank subcutaneous PDAC isografts were produced in 40 mice using PK5L1940 KPC cells. Intraperitoneal injections of the gamma secretase inhibitor, DAPT (5 mg/kg), were delivered daily for 7 days, starting 3 days prior to RT. A single dose of 20 Gy was administered to each flank tumor, and volumes were measured twice weekly. Colony formation assays of KPC cells were performed after RT, in the presence or absence of DAPT. Since stromal fibrosis can mediate radio-resistance in the tumor microenvironment (TME), the effect of tumor cells on Notch pathway activation in mouse fibroblasts (3T3 cells) was investigated using a luciferase reporter assay. Thus, 3T3 cells transfected with a Notch pathway luciferase reporter were incubated with PDAC cells for 48 h, followed by measurement of luciferase activity. In vivo, the combination of DAPT and RT significantly delayed tumor growth, and some tumors were completely eradicated. Mean tumor size for the combination at 21 days was 21 mm3 (range = 0-53, p = 0.005), while tumor size was 577 mm3 (range = 217-955, p = 0.69) for DAPT alone, 435 mm3 for RT alone (range = 51-932, p = 0.79), and 367 mm3 for untreated vehicle (range = 97-1144). Surprisingly, DAPT did not reduce clonogenic survival in vitro. Both ADAM10 knockout and DAPT decreased NICD cleavage and transcription of the downstream target Hes1 in vivo and in vitro. Co-culture with PDAC cells increased Notch luciferase reporter activity in fibroblasts. This effect was not mimicked by PDAC-conditioned media, suggesting a requirement for intercellular contact. Notch pathway inhibition sensitizes PDAC tumors to RT in vivo, but not in vitro, suggesting involvement of the TME. Indeed, co-culture with PDAC cells stimulates notch signaling in fibroblasts, suggesting non-cell autonomous mechanisms mediating fibrosis in the TME driving radioresistance. Future studies will determine if ADAM10 inhibition targeting PDAC cells and/or gamma secretase inhibition targeting the TME enhances radiation sensitivity in vivo by blocking fibroblast Notch signaling.