Radiotherapy Resistance Research Articles

Nanocarriers Targeting Circular RNA ADARB1 Boost Radiosensitivity of Nasopharyngeal Carcinoma through Synergically Promoting Ferroptosis.

Nasopharyngeal carcinoma (NPC) is a common malignant tumor of the head and neck, prevalent in regions such as Southern China and Southeast Asia. Radiotherapy serves as the primary clinical treatment for this carcinoma. However, resistance to radiotherapy is a fundamental cause of treatment failure and patient mortality, with the underlying mechanisms yet to be fully elucidated. We identified a recently characterized circular RNA, circADARB1, which is markedly upregulated in NPC tissues and closely associated with poor prognosis and radiotherapy resistance. Both in vitro and in vivo experiments demonstrated that circADARB1 inhibited ferroptosis, thereby inducing radiotherapy resistance in NPC cells. Building on these findings, we synthesized a biomimetic nanomaterial consisting of semiconducting polymer nanoparticles wrapped in cell membranes, designed to deliver both siRNA targeting circADARB1 and iron ions. The application of this nanomaterial not only efficiently suppressed the expression of circADARB1 and boosted intracellular iron concentrations, but also enhanced ferroptosis induced by radiotherapy, improving the radiosensitivity of NPC cells. Furthermore, our study revealed that circADARB1 upregulated the expression of heat shock protein HSP90B1, which repaired misfolded SLC7A11 and GPX4 proteins triggered by radiotherapy, thereby preserving their stability and biological functions. Mechanistically, SLC7A11 facilitated cysteine transportation into cells and glutathione synthesis, while GPX4 employed glutathione to mitigate intracellular lipid peroxidation induced by radiotherapy, shielding cells from oxidative damage and inhibiting ferroptosis, and ultimately leading to radiotherapy resistance in NPC cells. Our investigation elucidates molecular mechanisms with substantial clinical relevance, highlights the promising application prospects of nanotechnology in precision cancer therapy.

Dual Roles of microRNA-122 in Hepatocellular Carcinoma and Breast Cancer Progression and Metastasis: A Comprehensive Review

microRNA-122 (miR-122) plays crucial yet contrasting roles in hepatocellular carcinoma (HCC) and breast cancer (BC), two prevalent and aggressive malignancies. This review synthesizes current research on miR-122’s functions in these cancers, focusing on its potential as a diagnostic, prognostic, and therapeutic target. A comprehensive literature search was conducted using PubMed, Web of Science, and Scopus databases. In HCC, miR-122 is downregulated in most cases, suppressing oncogenic pathways and reducing tumor growth and metastasis. Restoring miR-122 levels has shown promising therapeutic potential, increasing sensitivity to treatments like sorafenib. In contrast, in BC, miR-122 plays a pro-metastatic role, especially in triple-negative breast cancer (TNBC) and metastatic lesions. miR-122′s ability to influence key pathways, such as the Wnt/β-catenin and NF-κB pathways in HCC, and its role in enhancing the Warburg effect in BC underline its significance in cancer biology. miR-122, a key factor in breast cancer radioresistance, suppresses tumors in radiosensitive cells. Inhibiting miR-122 could reverse resistance and potentially overcome radiotherapy resistance. Given its context-dependent functions, miR-122 could serve as a potential therapeutic target, where restoring or inhibiting its expression may help in treating HCC and BC, respectively. The dual roles of miR-122 underscore its significance in cancer biology and its potential in precision medicine.

Investigating the role of disulfidptosis related genes in radiotherapy resistance of lung adenocarcinoma

BackgroundRadiotherapy resistance is an important reason for high mortality in lung cancer patients, but the mechanism is still unclear. Dysregulation of cell proliferation and death plays a crucial role in the onset and progression of lung adenocarcinoma (LUAD). In recent times, a novel form of cellular demise called disulfidptosis, has attracted increasing attention. However, it is unclear whether the radiation-related disulfidptosis genes have prognostic role in LUAD.MethodsA complete suite of bioinformatics tools was used to analyze the expression and prognostic significance of radiation-related disulfidptosis genes. Afterward, we investigated the predictive significance of the risk signature in tumor microenvironments (TME), somatic mutations, and immunotherapies. In addition, we conducted a series of experiments to verify the expression of differentially expressed radiotherapy related disulfidptosis genes (DERRDGs) in vitro.ResultsA total of 88 DERRDGs were found. We constructed and validated a novel prognostic model based on PRELP, FGFBP1, CIITA and COL5A1. The enrichment analysis showed the DERRDG affected tumor prognosis by influencing tumor microenvironments (TME) and immunotherapy. And we constructed nomogram to promote clinical application. In addition, q-PCR confirmed the significant differences in the expression of prognostic genes between A549 irradiation-resistance cell and A549. Finally, western-blot, IHC staining, and small interference experiment suggested that PRELP may be a potential biomarker for radiotherapy resistance, whose low expression was associated with poor outcomes in LUAD patients.ConclusionThis study reveals the signature and possible underlying mechanisms of DERRDGs in LUAD and discovered the key gene PRELP, which helps to identify new prognostic biomarkers and provides a basis for future research.

Reshaping Immunosuppressive Tumor Microenvironment Using Ferroptosis/Cuproptosis Nanosensitizers for Enhanced Radioimmunotherapy

AbstractRadiotherapy, a traditional cancer treatment, not only controls local tumor growth but also potentially induces immunogenic cell death, initiating systemic immune responses. However, radiotherapy resistance and immunosuppressive tumor microenvironments often limit the potency of radiation‐induced anti‐tumor immune responses, rendering them insufficient for clinical applications. Consequently, trimetallic nanoparticles are constructed with dual enzymatic activity, AuBiCu‐distearoyl phosphoethanolamine‐PEG nanoparticles (AuBiCu‐PEG NPs), to synergistically improve radiotherapy resistance through X‐ray deposition, hypoxia alleviation, and ferroptosis and cuproptosis induction. This approach promotes radiotherapy‐induced immunogenic cell death and boosts anti‐tumor immune responses. Furthermore, AuBiCu‐PEG NPs effectively reversed radiation‐induced upregulation of programmed cell death 1 ligand 1 (PD‐L1), inhibit tumor immune evasion, and reshaped the immune microenvironment. Non‐invasive and real‐time longitudinal monitoring of nanoparticle accumulation in tumors can be achieved using spectral computed tomography (CT) and photoacoustic (PA) imaging. In summary, the designed AuBiCu‐PEG NPs serve as promising nanoplatforms for immune microenvironment remodeling and can be used in multimodal molecular imaging‐guided ferroptosis‐cuproptosis‐enhanced radiotherapy.

Exploring MPC1 as a potential ferroptosis-linked biomarker in the cervical cancer tumor microenvironment: a comprehensive analysis

BackgroundThe increasing problems of drug and radiotherapy resistance in cervical cancer underscores the need for novel methods for its management. Reports indicate that the expression of MPC1 may be associated with the tumor microenvironment and the occurrence of ferroptosis in cervical cancer. The objective of this study was to visually illustrate the prognostic significance and immunological characterization of MPC1 in cervical cancer.MethodsThe expression profile and prognostic significance of MPC1 were analyzed using various databases, including UALCAN, TIMER2, GEPIA2, and Kaplan–Meier Plotter. TISIDB, TIMER2, and immunohistochemical analysis were used to investigate the correlation between MPC1 expression and immune infiltration. GO enrichment analysis, KEGG analysis, Reactome analysis, ConsensusPathDB, and GeneMANIA were used to visualize the functional enrichment of MPC1 and signaling pathways related to MPC1. The correlation analysis was carried out to examine the relationship between MPC1 and Ferroptosis gene in TIMER 2.0, ncFO, GEPIA Database and Kaplan–Meier Plotter.ResultsWe demonstrated that the expression levels of MPC1 in cervical cancer tissues were lower than those in normal cervical tissues. Kaplan–Meier survival curves showed shorter overall survival in cervical cancer patients with low levels of MPC1 expression. The expression of MPC1 was related to the infiltrating levels of tumor-infiltrating immune cells in cervical cancer. Moreover, MPC1 expression was associated with the iron-mediated cell death pathway, and several important ferroptosis genes were upregulated in cervical cancer cells. Furthermore, after knocking down MPC1 in HeLa cells, the expression of these genes decreased.ConclusionThese findings indicate that MPC1 functions as a prognostic indicator and plays a role in the regulation of the ferroptosis pathway in cervical cancer.

RRFERV stabilizes TEAD1 expression to mediate nasopharyngeal cancer radiation resistance rendering tumor cells vulnerable to ferroptosis.

Long noncoding RNAs (lncRNAs) regulate various essential biological processes, including cell proliferation, differentiation, apoptosis, migration, and invasion. However, in nasopharyngeal carcinoma (NPC), the clinical significance and mechanisms of lncRNAs in malignant progression are unknown. RNA sequencing and bioinformatic analysis were used to determine the potential function of RRFERV (radiation-resistant but ferroptosis vulnerable), and its biological effects were investigated using in vitro and in vivo experiments. Western blotting, quantitative real-time reverse transcription PCR, RNA immunoprecipitation (RIP) assays, and flow cytometry detected RRFERV expression. Ferroptosis and lipid peroxidation were added to evaluate the relationship between it and radiotherapy resistance. LncRNA-RRFERV was both highly expressed in NPC tissues and radiation-resistant cells. RRFERV is associated with poor clinical outcomes of NPC patients and stabilizes TEAD1 by competitive binding with microRNA-615-5p and microRNA-1293. RRFERV-TEAD1 signaling axis leads to malignant progression and radiotherapy resistance of NPC. Furthermore, we observed that NPC radiotherapy resistance cells exist in a fragile oxidative stress equilibrium, which makes them more sensitive to ferroptosis inducers. Surprisingly, we found that RRFERV-TEAD1 signaling axis also plays a key role in mediating the lipid peroxidation levels of NPC radiotherapy resistance cells through transcriptional activation of ACSL4/TFRC. RRFERV serves as an independent prognostic factor in NPC. During the malignant progression of NPC caused by high expression of RRFERV, ferroptosis can be induced to effectively kill cancer cells and reverse the radiotherapy resistance of NPC cells, suggesting a potential treatment approach for recurrent and refractory NPC.

Leucine restriction ameliorates Fusobacterium nucleatum-driven malignant progression and radioresistance in nasopharyngeal carcinoma

Radiotherapy resistance is the main cause of treatment failure among patients with nasopharyngeal carcinoma (NPC). Recently, increasing evidence has linked the presence of intratumoral Fusobacterium nucleatum (Fn) with the malignant progression and therapeutic resistance of multiple tumor types, but its influence on NPC has remained largely unknown. We found that Fn is prevalent in the tumor tissue of patients with NPC and is associated with radioresistance. Fn invaded and proliferated inside NPC cells and aggravated tumor progression. Mechanistically, Fn slowed mitochondrial dysfunction by promoting mitochondrial fusion and decreasing ROS generation, preventing radiation-induced oxidative damage. Fn inhibited PANoptosis by the SLC7A5/leucine-mTORC1 axis during irradiation stress, thus promoting radioresistance. Treatment with the mitochondria-targeted antibiotics or dietary restriction of leucine reduced intratumoral Fn load, resensitizing tumors to radiotherapy invivo. These findings demonstrate that Fn has the potential to be a predictive marker for radioresistance and to help guide individualized treatment for patients with NPC.

375 (PB363): Investigating cell-cell communication in glioblastoma: implications for radiotherapy resistance and therapeutic strategies

375 (PB363): Investigating cell-cell communication in glioblastoma: implications for radiotherapy resistance and therapeutic strategies

Targeting Cervical Cancer Stem Cells by Phytochemicals.

Cervical cancer (CaCx) poses a significant global health challenge, ranking as the fourth most common cancer among women worldwide. Despite the emergence of advanced treatment strategies, recurrence remains a bottleneck in favorable treatment outcomes and contributes to poor prognosis. The chemo- or radio-therapy resistance coupled with frequent relapse of more aggressive tumors are some key components that contribute to CaCx-related mortality. The onset of therapy resistance and relapse are attributed to a small subset of, slow-proliferating Cancer Stem Cells (CSC). These CSCs possess the properties of tumorigenesis, self-renewal, and multi-lineage differentiation potential. Because of slow cycling, these cells maintain themselves in a semi-quiescent stage and protect themselves from different anti-proliferative anti-cancer drugs. Keeping in view recent advances in their phenotypic and functional characterization, the feasibility of targeting CSC and associated stem cell signaling bears a strong translational value. The presence of CSC has been reported in CaCx (CCSC) which remains a forefront area of research. However, we have yet to identify clinically useful leads that can target CCSC. There is compelling evidence that phytochemicals, because of their advantages over synthetic anticancer drugs, could emerge as potential therapeutic leads to target these CCSCs. The present article examined the potential of phytochemicals with reported anti-CSC properties and evaluated their future in preclinical and clinical applications against CaCx.

Cephalomannine reduces radiotherapy resistance in non-small cell lung cancer cells by blocking the β-catenin-BMP2 signaling pathway

BackgroundThe management of non-small cell lung cancer (NSCLC) often includes the use of radiotherapy, with individual outcomes being impacted by the tumor's response to this treatment modality. Cephalomannine (CPM), a taxane diterpenoid found in Taxus spp, has been found to have anti-tumor activity. This study was aim to the explore the role and mechanism by which CPM affects radiotherapy resistance in NSCLC. MethodsH460 cells were pretreated with different doses of CPM. H460 cells were transfected with β-catenin overexpression plasmids. The cell viability, colony-forming ability, migration ability, and sphere-forming ability and apoptosis of the cells were measured by using CCK-8, colony-forming, transwell, and sphere-forming assay and flow cytometry. Western blot assay was employed to detect the expression of β-catenin and BMP2. ResultsThe cell viability, proliferation, migration and sphere-forming ability of cells in the radiotherapy-resistant (RR) group were significantly higher than those in the radiotherapy-sensitivity (RS) group. Conversely, the apoptosis rate of cells in the RR group was lower than that in the RS group. However, after CPM pretreatment of RR group cells, the above phenomena were reversed in a CPM dose-dependent manner. Subsequently, pretreatment with CPM resulted in a decrease in the expression levels of β-catenin and BMP2 in the RR group. In addition, overexpression of β-catenin mitigated the inhibitory effects of CPM on radiotherapy-resistant NSCLC cells. ConclusionCPM has the potential to decrease radiotherapy resistance in NSCLC cells by inhibiting the β-catenin-BMP2 signaling pathway, promoting apoptosis, and ultimately impeding cell growth.

Targeting MGST1 Makes Non-Small Cell Lung Cancer Cells Sensitive to Radiotherapy by Epigenetically Enhancing ALOX15-Mediated Ferroptosis.

Ferroptosis is closely related to radiotherapy resistance in multiple can-cers. Herein, the role of microsomal glutathione S-transferase 1 (MGST1) in regulating ferropto-sis and radiotherapy resistance in non-small cell lung cancer (NSCLC) was investigated. Radiation-resistant NSCLC cells (NCI-1299-IR and HCC827-IR cells) were estab-lished. After exposure to X-ray, cell proliferation and survival were assessed by colony formation assay and CCK-8 assay, and lipid ROS level was examined by the fluorophore BODIPY™ 581/591 C11. MDA, GSH, and Fe2+ levels were measured by ELISA kits. The molecular interac-tion was analyzed using ChIP and MSP assays. Our results showed that RSL3 treatment greatly enhanced the radiotherapy sensitivity of NCI-1299-IR and HCC827-IR cells. It was subsequently revealed that MGST1 was highly ex-pressed in NCI-1299-IR and HCC827-IR cells than its parent cells, and silencing of MGST1 re-duced radioresistance of NCI-1299-IR and HCC827-IR cells by facilitating ferroptosis. Mechanis-tically, MGST1 knockdown greatly reduced HO-1 and DNMT1/3A protein levels, leading to re-duced DNA methylation on the ALOX15 promoter region, thereby epigenetically upregulating ALOX15 expression. As expected, the promoting effects of MGST1 silencing on radiosensitivity and ferroptosis in radiation-resistant NSCLC cells were strikingly eliminated by ALOX15 knock-down. MGST1 knockdown epigenetically enhanced radiotherapy sensitivity of NCSLC cells by promoting ALOX15-mediated ferroptosis through regulating the HO-1/DNMT1 pathway.

The Effect of C-X-C Motif Chemokine Ligand 12 in Colorectal Cancer Associated with Chemoresistance and Radioresistance as Well as Stemness.

We aimed to explore the role of C-X-C motif chemokine ligand 12 (CXCL12) and cytokinecytokine receptor interaction signaling pathway in the radiotherapy and chemotherapy resistance as well as cell stemness in colorectal cancer (CRC). Bioinformatics analysis was used to identify the differentially expressed mRNAs and signal pathways closely related to differentially expressed mRNAs have also been analyzed in March 2022 at the Jinhua Central Hospital, China. Then, the expression of CXCL12 was detected by qRT-PCR in colorectal cancer cells and testing the effects of transfecting CXCL12 into different CRC-derived cell lines. The effects of CXCL12 on cell proliferation were evaluated by chemosensitivity assay and radiation sensitivity assay. Bioinformatics analysis of DEGs found a total of 2429 differentially expressed genes, THBS3 and CXCL12 genes are two abnormally highly expressed genes in the CRC. KEGG analysis showed the correlative signaling pathway, cytokine-cytokine receptor interaction, which is related to cell stemness. Furthermore, the expression of CXCL12 in CRC cells was detected and an increasing trend was obtained in CRC cells. In addition, the chemosensitivity and radiotherapy tolerance were elevated after transfected with CXCL12. CXCL12 could be a potential promote biomarkers in CRC and also promote the chemosensitivity and radiotherapy tolerance.

Abstract B086: Patient-derived pancreatic tumor organoids as a tool to evaluate cancer stem cell populations and their role in therapeutic resistance

Abstract Introduction: Pancreatic ductal adenocarcinoma remains one of the most lethal forms of cancer with a five-year survival rate of less than 15%. Regardless of surgery eligibility, most patients receive systemic chemo-radiation therapy, which includes FOLFIRINOX or gemcitabine and nab-paclitaxel, often followed by radiation therapy (RT) with or without 5-FU. Unfortunately, patients’ tumors frequently develop resistance to these therapies, and it’s often unclear as to why. One potential source of resistance and recurrence is cancer stem cell (CSC) perseverance following treatment. Purpose: The purpose of this study was to characterize and treat three patient-derived pancreatic tumor organoids (IDs: 8510, 7800, and 11777) with RT and LD50 doses of relevant chemotherapy drugs to evaluate the treatment response. Furthermore, we sought to examine the impact of individual and combination treatments (i.e., chemo-RT) on the population of CSCs in these organoids. Methods: Organoids were cultured in 3D BME gel domes and grown in an NCI-recommended media formulation. Genome sequencing of 505 relevant genes was performed using a PGDx kit. The dose responses of three organoids to radiation (2-12 Gy) and several chemotherapy approaches were determined via MTT assay. CSCs were identified as those cells staining positive for markers SOX2 and OCT4. The population of CSCs before and after chemotherapy, RT, and combined chemo-RT were evaluated with immunofluorescence, western blotting, and flow cytometry. Results: The data revealed a variation in the responses of tumor organoids to treatments, as demonstrated by different LD50 doses. For instance, tumor organoid 8510 exhibited higher tolerance to 5-FU and FOLFIRINOX treatments compared to organoid 7800. Interestingly, organoid 11777 showed resistance to RT, unlike organoids 8510 and 7800. Clinical genomic sequencing revealed that organoid 11777 showed unique variants of several genes known to be involved with DNA repair, including PIM1, RAD54L, and SLX4, as well as mutations in the ARID1b and TGFBR2 genes. The latter two genes may have implications for radiation resistance and could explain the unique resistance of organoid 11777 to RT. Further investigation is warranted. Regarding the population of CSCs, the immunofluorescence data has confirmed the presence of SOX2 and OCT4 in these organoids, and the immunoblot data showed an upregulation of SOX2 and OCT4 in tumor organoids treated with radiation alone. Flow cytometry analysis confirmed that the percentage of CSCs increased following radiation treatment; however, the CSC population was slightly decreased following treatment with FOLFIRINOX and significantly decreased after combination treatment with FOLFIRINOX and RT. Conclusions: Patient-derived pancreatic tumor organoids can be used as a surrogate to provide molecular insights and therapeutic sensitivity profiles in individual patients. Additionally, while the data suggests a link between CSCs and RT resistance, the combination approach results in a more pronounced inhibition of the CSC population. Citation Format: Zachery L Keepers, Sanjit Roy, William Ryan, Binny Bhandary, Narottam Lamichhane, France Carrier, Ramaswamy K Iyer, Jason K Molitoris, William F Regine, Hem D Shukla. Patient-derived pancreatic tumor organoids as a tool to evaluate cancer stem cell populations and their role in therapeutic resistance [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr B086.

Analysis of the Mechanism Underlying Radiotherapy Resistance Caused by Oligodendroglia Cells in Glioblastoma by Applying the Single-cell RNA Sequencing Technology.

Glioblastoma (GBM) is an aggressive malignancy. The inherent resistance of GBM to radiotherapy poses great challenges for clinical treatment. The primary objective of this study is to explore the molecular mechanisms of radiotherapy resistance in GBM and identify the key influencing factors that contribute to this phenomenon. The single-cell RNA sequencing (scRNA-seq) data of GBM were downloaded from the Gene Expression Omnibus (GEO) database. Cells were clustered using the Seurat R package, and the clusters were annotated using the CellMarker database. Pseudotime analysis was conducted using Monocle2. Marker scores were calculated based on the RNA-seq data of GBM from the UCSC database, and the enrichment of Hallmark gene sets was measured with the AUCell package. Furthermore, the most frequently mutated genes were identified using the simple nucleotide variation data from The Cancer Genome Atlas (TCGA) applying the maftools package. This study identified two oligodendrocyte subsets (ODC3 and ODC4) as radiotherapy-resistant groups in GBM. Enrichment and Pseudotime analysis revealed that the inflammatory response and immune activation pathways were enriched in ODC3, while the cell division and interferon response pathways were enriched in ODC4. The enrichment scores of hallmark gene sets further confirmed that ODC3 and ODC4 subpopulations developed radiotherapy resistance via distinct molecular mechanisms. Analysis of gene mutation frequencies showed that TP53 exhibited the most significant change in mutation frequency, indicating that it was an important risk factor involved in radiotherapy resistance in GBM. We identified two ODC subpopulations that exhibited resistance to radiotherapy, providing a new perspective and potential targets for personalized treatment strategies for GBM.

PRMT1 promotes radiotherapy resistance in glioma stem cells by inhibiting ferroptosis.

The existence of glioma stem cells (GSCs) in cancer is related to glioma radiotherapy resistance. In this research, the effect of protein arginine methyltransferase 1 (PRMT1) on the radiosensitivity of glioma stem cell (GSC)-like cells, as well as its underlying mechanism, was investigated. GSCs-like cells were analyzed and identified by flow cytometry. The self-renewal capability was evaluated by sphere-forming assay. The PRMT1 expression level in glioblastoma were analyzed using the Gene Expression Profiling Interactive Analysis database. The mRNA and protein were scrutinized by RT-qPCR and western blot, respectively. The radiosensitivity was evaluated by clonogenic survival assay. Ferroptosis was evaluated by detecting the levels of reactive oxygen species, malondialdehyde, Fe2+, glutathione, and 4-hydroxynonenal. U87 and SHG44 cells with GSC-like phenotype (GSC-U87 and GSC-SHG44) displayed strong expression of CD133 and nestin versus the glioma cells. GSC-U87 and GSC-SHG44 possess the self-renewal capability. The level of PRMT1 was higher in glioblastoma tumor tissues than in the normal paracancer tissues. Knockdown of PRMT1 enhanced the radiotherapy sensitivity of GSCs-like cells, which wasevidenced by reduced survival fraction in GSC-U87 and GSC-SHG44 underwent sh-PRMT1 transfection. But, this effect was attenuated by Fer-1 (a ferroptosis inhibitor) treatment, accompanied by the abatement of ferroptosis. PRMT1 promoted radiotherapy resistance in GSCs-like cells by inhibiting ferroptosis.

Glutathione S-transferase-Pi 1 protects cells from irradiation-induced death by inhibiting ferroptosis in pancreatic cancer.

Glutathione S-transferase-Pi 1 (GSTP1) is an isozyme that plays a key role in detoxification and antioxidative damage. It also confers resistance to tumor therapy. However, the specific role of GSTP1 in radiotherapy resistance in pancreatic cancer (PC) is not known. In this study, we investigated how GSTP1 imparts radioresistance in PC. The findings of previous studies and this study revealed that ionizing radiation (IR) induces ferroptosis in pancreatic cancer cells, primarily by upregulating the expression of ACSL4. Our results showed that after IR, GSTP1 prolonged the survival of pancreatic cancer cells by inhibiting ferroptosis but did not affect apoptosis. The expression of GSTP1 reduced cellular ferroptosis by decreasing the levels of ACSL4 and increasing the GSH content. These changes increase the resistance of pancreatic cancer cells and xenograft tumors to IR. Our findings indicate that ferroptosis participates in irradiation-induced cell death and that GSTP1 prevents IR-induced death of pancreatic cancer cells by inhibiting ferroptosis.

NEDD4L affects KLF5 stability through ubiquitination to control ferroptosis and radiotherapy resistance in oesophageal squamous cell carcinoma.

Oesophageal squamous cell carcinoma (ESCC) contributes to high mortality. Modulating ferroptosis may reverse resistance to radiotherapy. This article was to explore the ubiquitination modification of KLF5 and its effect on ferroptosis in ESCC. KLF5 was under-expressed by shRNA plasmids in the cells and ROS levels were analysed by flow cytometry, ferroptotic gene expression was detected by qRT-PCR, MDA and GSH levels were determined by ELISA, cell morphology was observed by transmission electron microscopy, and Fe ion levels were analysed by immunofluorescence. Cells were treated with Ferrostatin-1 and NAC and analysed for cell proliferation by colony formation assay, cell migration and invasion by Transwell assays, and apoptosis by flow cytometry. DNA damage in cells was also analysed using comet assay, EdU doping assay, γH2AX fluorescence, DNA-PKcs and PCR. NEDD4L and KLF5 binding was analysed by immunoprecipitation. Changes in ferroptosis, DNA damage and resistance were analysed in cells with both silencing NEDD4L and KLF5. Changes in tumour resistance to radiation were analysed in mice underexpressing NEDD4L and KLF5. Low expression of KLF5 significantly promotes cellular lipid peroxidation levels, with decreased expression of SOD and GPX4, and increased expression of ACSL4. Concurrently, MDA levels deplete GSH, and cells exhibit typical ferroptotic morphology with increased Fe2+ content. KLF5 inhibition results in enhanced cellular clonogenicity, migration and invasion activities, reduced apoptosis, increased tail DNA, nuclear EdU incorporation, nuclear γH2AX foci and elevated expression of DNA-PKcs, LIG4, RAD9B and BMI1. Ferrostatin-1 and NAC reverse these effects. NEDD4L ubiquitination modifies and degrades KLF5, with NEDD4L/KLF5 inhibition mitigating cellular ferroptosis and DNA damage, thereby promoting radiosensitivity both invitro and invivo. NEDD4L increases radiosensitivity by accelerating cellular ferroptosis via ubiquitination modification of KLF5.

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.

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.

DOT1L-mediated RAP80 methylation promotes BRCA1 recruitment to elicit DNA repair

Breast Cancer Type 1 Susceptibility Protein (BRCA1) is a tumor-suppressor protein that regulates various cellular pathways, including those that are essential for preserving genome stability. One essential mechanism involves a BRCA1-A complex that is recruited to double-strand breaks (DSBs) by RAP80 before initiating DNA damage repair (DDR). How RAP80 itself is recruited to DNA damage sites, however, is unclear. Here, we demonstrate an intrinsic correlation between a methyltransferase DOT1L-mediated RAP80 methylation and BRCA1-A complex chromatin recruitment that occurs during cancer cell radiotherapy resistance. Mechanistically, DOT1L is quickly recruited onto chromatin and methylates RAP80 at multiple lysines in response to DNA damage. Methylated RAP80 is then indispensable for binding to ubiquitinated H2A and subsequently triggering BRCA1-A complex recruitment onto DSBs. Importantly, DOT1L-catalyzed RAP80 methylation and recruitment of BRCA1 have clinical relevance, as inhibition of DOT1L or RAP80 methylation seems to enhance the radiosensitivity of cancer cells both in vivo and in vitro. These data reveal a crucial role for DOT1L in DDR through initiating recruitment of RAP80 and BRCA1 onto chromatin and underscore a therapeutic strategy based on targeting DOT1L to overcome tumor radiotherapy resistance.