Hypoxic tumors are sensitive to FLASH radiotherapy
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE223607 | GEO | 2024/01/24
REPOSITORIES: GEO
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Project description:Thoracic radiation therapy is limited by the development of acute (i.e. pneumonitis) and late (i.e. pulmonary fibrosis) side-effects. The goal of this study is to analyze, at the single cell level, the molecular impact of two radiation treatments : a conventional/clinical (CONV) modality vs. FLASH, a new radiation method that spares healthy tissue from late radiation-induced toxicities (Science Translational Medicine 6: 245ra293, 2014). We analyzed by single cell RNA sequencing (scRNAseq) dissociated lung cells from a non-irradiated control mouse (NI), a mouse 4 days after CONV thoracic irradiation (CONV) and a mouse 4 days after FLASH irradiation (FLASH). We identify transcriptional alterations induced in the distinct lung cell types after irradiation and show that FLASH irradiated lung cells present a reduced pro-inflammatory phenotype as well as a diminished activation of epithelial lung progenitor cells. In line with previous report (Radiother Oncol 124: 365-9, 2017), this study indicates that FLASH radiation therapy limits inflammation and preserves the regenerative capcity of the lung.
2019-12-07 | GSE133992 | GEO
Project description:AsiDNA, a cholesterol-coupled oligonucleotide mimicking double-stranded DNA breaks, was developed to sensitize tumour cells to radio- and chemotherapy. This drug acts as a decoy hijacking the DNA damage response. Previous studies have demonstrated that standalone AsiDNA administration is well tolerated with no additional adverse effects when combined with chemo- and/or radiotherapy. This lack of normal tissue complication encouraged further examination into the role of AsiDNA in normal cells. The delayed development of pulmonary fibrosis after FLASH-RT compared to CONV-RT might be a known phenomenon but the complexity behind this specific tissue response is completely unidentified. Radiation has been shown to impact various cell types presented in the lung, resulting in changes in cellular activity and numerous pathway activations. Current unpublished data suggest a clear variety between the CONV and FLASH-RT gene signatures examined using single cell RNA sequencing. As the combined treatment of AsiDNA with CONV-RT resulted in a delay in radiation induced lung fibrosis compared to CONV-RT standalone, it is to be questioned if the signature of AsiDNA CONV-RT is similar to FLASH-RT or CONV-RT. To characterize the similarity in cellular changes and expression signatures in lungs 5 months post CONV-RT, FLASH-RT, AsiDNA CONV-RT or non-irradiated (Control) treatment. Single cell RNA sequencing of irradiated lungs revealed a closer resemblance between CONV AsiDNA and FLASH-RT in profibrotic gene signatures within the fibroblast and macrophages population, in comparison to CONV-RT standalone. Collectively, this information indicates that the activity of AsiDNA and FLASH-RT could draw upon identical mechanism interference to result in the protective capacities within the normal tissue.
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Project description:Tumor hypoxia is linked to poor outcome for many cancers, but the underlying mechanisms and the environmental factors that initiate tumor hypoxia are poorly understood. Here, we tracked tumor hypoxia in glioblastoma (GBM), a highly malignant brain cancer, in immunocompetent mice with a sensitive fluorescent reporter combined with single cell transcriptomics. We found that hypoxic GBM cells are quiescent and display a mesenchymal transition, both linked to malignant potency. We also captured in vivo hypoxia gene signature, which is more represented in recurrent GBM and predicts worse outcome. Interestingly, hypoxic GBM cells is a diverse population, consisted of four subclusters, and enriched for immune pathways. Concordantly, our reporter highlighted a distinct geographic pattern of immune cells in hypoxic regions, with phagocytic tumor-associated macrophages (TAMs) and CD8+ cytotoxic T cells (CTLs) congregated in hypoxic cores confined by hypoxic GBM cells in pseudopalisading patterns. Mechanistically, this is a dynamic temporospatial process, requiring cytokine CCL8. Remarkably, the sequestered TAMs also experience hypoxia, and they are reprogrammed to an immunotolerant state by factors released from hypoxic GBM cells. Contrary to the conventional viewpoint that hypoxia arises from rapid tumor expansion outstripping vascular supply, we discovered anticancer immunity as an important driving force of tumor hypoxia. Attenuating immune responses by implanting GBM in host mice with immunodeficiency or IL1β deletion significantly decreased GBM hypoxia in well-established tumors. Unexpectedly, radiation therapy (XRT) greatly reduced tumor hypoxia, and when combined with evofosfamide, a prodrug activated by hypoxia, achieved enhanced efficacy in tumor shrinkage and eradication of hypoxic GBM population. Analyses of human patient GBM samples highlighted a connection of mesenchymal subtype, immune response, and tumor hypoxia, all contributing to poor survival. Altogether, our study revealed a reciprocal influence of anti-tumor immunity and tumor hypoxia, which has important ramification for prognosis and immunotherapy for GBM.
2023-03-31 | GSE179077 | GEO
Project description:The molecular and cellular mechanisms driving the enhanced therapeutic ratio of ultra-high dose-rate radiotherapy (FLASH-RT) over slower conventional (CONV) ionizing radiation (IR) dose-rate are not known. However, attenuated DNA damage and transient oxygen depletion are among a number of proposed models. Here, we tested whether FLASH-IR under physioxic (4% O2) and hypoxic conditions (≤2% O2) attenuates detection of genome-wide translocations relative to CONV dose rates and whether any differences identified revert under normoxic (21% O2) conditions. We employed high-throughput rejoin and genome-wide translocation sequencing (HTGTS-JoinT-seq), usingS. pyogenesandS. aureusCas9 “bait” DNA double strand breaks (DSBs), to measure differences in proximal deletions, inversions, and excision circles and their translocation to “prey” genome-wide DSBs generated by CONV (0.08-0.13Gy/s) and FLASH (1x102-5x106Gy/s) dose rates, under varying IR doses and oxygen tensions. Normoxic and physioxic IR exposure in HEK293T cells increased translocations at the cost of decreasing proximal repair but were indistinguishable between CONV and FLASH dose-rates. Although decreased numbers of translocations were recovered as cells transitioned to hypoxic (<2%) conditions, the combined decrease in oxygen tension with IR dose-rate modulation did not reveal significant differences in the level of translocations nor in junction structures, which, for proximal repair, were increased in direct and short microhomologies. We conclude that irrespective of oxygen tension, FLASH IR dose rates produce translocations and junction structures at levels that are indistinguishable from CONV dose rates.
2023-03-29 | GSE227466 | GEO
Project description:Glioblastoma multiforme (GBM) is the most aggressive malignant primary brain tumor with a dismal mean survival even with the current standard of care. Although in vitro cell systems can provide mechanistic insight into the regulatory networks governing GBM cell proliferation and migration, clinical samples provide a more physiologically relevant view of oncogenic signaling networks. However, clinical samples are not widely available and may be embedded for histopathologic analysis. With the goal of accurately identifying activated signaling networks in GBM tumor samples, we investigated the impact of embedding in optimal cutting temperature (OCT) compound followed by flash freezing in LN2 vs. immediate flash freezing (iFF) in LN2 on protein expression and phosphorylationmediated signaling networks. Quantitative proteomic and phosphoproteomic analysis of 8 pairs of tumor specimens revealed minimal impact of the different sample processing strategies and highlighted the large inter-patient heterogeneity present in these tumors. Correlation analyses of the differentially processed tumor sections identified activated signaling networks present in selected tumors and revealed the differential expression of transcription, translation, and degradation associated proteins. This study demonstrates the capability of quantitative mass spectrometry for identification of in vivo oncogenic signaling networks from human tumor specimens that were either OCT-embedded or immediately flash-frozen.
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Project description:Oxygen fluctuation during tissue remodeling imposes a major metabolic challenge in human tumors. Stem-like tumor cells in glioblastomas are believed to possess extraordinary metabolic flexibility, enabling them to initiate growth even under non-permissive conditions. To identify adaptive response mechanism, we compared the effects of acute and chronic hypoxia versus oxygenation on stem-like glioblastoma (GS) cells. GS cell lines were established and propagated either under normoxia (21% O2) or hypoxia (1% O2) and subsequently exposed to acute normoxia or hypoxia, respectively. Gene expression profiling revealed that acute hypoxia predominantly induced metabolic pathways and cell cycle arrest, whereas chronic hypoxia activated neurodevelopmental processes. In particular, we found increased expression of glycolytic enzymes, especially of the preparatory phase of glycolysis, under acute hypoxia, whereas pentose phosphate pathway (PPP) enzymes were downregulated. The opposite was found for acute oxygenation of hypoxic GS cells. Findings were confirmed by qPCR and immunoblot analyses. Despite downregulation by hypoxia, expression of PPP enzymes is increased in GBMs compared to normal brain, whereas expression of hypoxia-inducible enzymes of the parallel preparatory phase of glycolysis is decreased. Immunohistochemistry revealed strong staining for PPP enzymes in the bulk of GBM tissue, especially in highly proliferative areas, but not in pseudopalisading (hypoxic) cells. Glycolytic enzymes displayed an inverse pattern. Mass spectrometric analysis using [1,2-13C2]-D-glucose showed reduced glucose flux through the PPP under hypoxia in favor of flux through glycolysis. Acute and chronic hypoxia increased cell migration but reduced proliferation, whereas normoxia had opposite effects. Our findings extend Warburg’s observations by showing that in most tumor cells the PPP, which supplies metabolites for biomass production, is favored over the parallel preparatory phase of glycolysis, but is suppressed under acute severe hypoxia, causing a switch to direct glycolysis to protect against hypoxic stress.
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Project description:PD-L1 Inhibitor Regulates the miR-33a-5p/PTEN Signaling Pathway and Can Be Targeted to Sensitize Glioblastomas to Radiation. Glioblastoma (GBM) is the most common and lethal brain tumor in adults. Ionizing radiation (IR) is a standard treatment for GBM patients and results in DNA damage. However, the clinical efficacy of IR is limited due to therapeutic resistance. The programmed death ligand 1 (PD-L1) blockade has a shown the potential to increase the efficacy of radiotherapy by inhibiting DNA damage and repair responses. The miR-33a-5p is an essential microRNA that promotes GBM growth and self-renewal. In this study, we investigated whether a PD-L1 inhibitor (a small molecule inhibitor) exerted radio-sensitive effects to impart an anti-tumor function in GBM cells by modulating miR-33a-5p. U87 MG cells and U251 cells were pretreated with PD-L1 inhibitor. The PD-L1 inhibitor-induced radio-sensitivity in these cells was assessed by assaying cellular apoptosis, clonogenic survival assays, and migration. TargetScan and luciferase assay showed that miR-33a-5p targeted the phosphatase and tensin homolog (PTEN) 3' untranslated region. The expression level of PTEN was measured by western blotting, and was also silenced using small interfering RNAs. The levels of DNA damage following radiation was measured by the presence of γ-H2AX foci, cell cycle, and the mRNA of the DNA damage-related genes, BRCA1, NBS1, RAD50, and MRE11. Our results demonstrated that the PD-L1 inhibitor significantly decreased the expression of the target gene, miR-33a-5p. In addition, pretreatment of U87 MG and U251 cells with the PD-L1 inhibitor increased radio-sensitivity, as indicated by increased apoptosis, while decreased survival and migration of GBM cells. Mir-33a-5p overexpression or silencing PTEN in U87 MG and U251 cells significantly attenuated PD-L1 radiosensitive effect. Additionally, PD-L1 inhibitor treatment suppressed the expression of the DNA damage response-related genes, BRCA1, NBS1, RAD50, and MRE11. Our results demonstrated a novel role for the PD-L1 inhibitor in inducing radio- sensitivity in GBM cells, where inhibiting miR-33a-5p, leading to PTEN activated, and inducing DNA damage was crucial for antitumor immunotherapies to treat GBM.
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