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Abdollahi, A.

Publications and source records attributed to Abdollahi, A..

11 recordsLinked to original sources
bioRxiv2025

High LET Radiation: A Novel Strategy to Overcome Tumor Microtubes -Mediated Radioresistance in Glioblastoma

PurposeTumor cell networks formed by tumor microtubes (TMs) are thought to drive therapy resistance in glioblastoma (GB). X-ray irradiation enhances TM formation, thereby increasing radioresistance. We hypothesize that high linear energy transfer (LET) particle radiotherapy is less affected by TM-mediated resistance due to its reduced reliance on indirect DNA damage. This study explores the impact of LET-induced DNA damage on TMs formation and GB survival Material and MethodsFormation of TMs was investigated in the primary patient derived glioblastoma stem-like cell lines (S24 and T269) irradiated with different LET, ranging from 3 - 107 keV/{micro}m, across dose series (1, 2, 4, 6 Gy) of clinical proton, helium, and carbon ion beams. TM networks and DNA damage patterns, specifically {gamma}H2AX foci, were visualized using fluorescence microscopy. Cell survival was evaluated through clonogenic survival assays. ResultsThe formation of TMs, radiation-induced nuclear DNA damage repair foci, and GB cell survival were correlated with a gradual increase in LET. Consistent with conventional photon/X-rays, low-LET proton irradiation promoted TMs formation in a dose-dependent manner. In contrast, an anti-correlation between LET and TMs induction was found, i.e., a decreased network connectivity with gradual increase of LET and formation of complex DNA damage. Consequently, LET increase correlated with reduced cell survival, with the most pronounced cell killing observed after high-LET carbon irradiation. Moreover, the inverse correlation between LET and TMs density was further confirmed for a broad range of LET modulated within the carbon ion irradiation. ConclusionThis is the first report on the relevance of LET as a novel mean to overcome TMs network-mediated radioresistance in GB, with ramifications for the clinical translation of high-LET particle radiotherapy to further improve outcome in this still devastating disease.

cancer biology↗
bioRxiv2024

Personalized Medicine for Meningiomas: Drug Screening on Tumor Organoids Exposes Therapeutic Vulnerabilities to HDAC1/2i Panobinostat

Managing aggressive meningiomas remains challenging due to limited treatment options besides surgical tumor removal and radiotherapy. To identify novel therapies for aggressive meningiomas, we established a multi-step drug screening workflow, focusing on targetable genes obtained from transcriptome data of highly aggressive grade 3 meningiomas. In vitro screening of 107 targeted drugs identified nine effective inhibitors. To study these drugs in a more natural environment, we established a standardized patient-derived tumor organoid (TO) model preserving accurately the original tissues genotype and phenotype. Individual drug responses were assessed in TOs from 60 molecularly characterized meningioma cases. Especially the FDA-approved epigenetic drug panobinostat demonstrated high antimeningioma efficacy in 70% of TOs, mediated through HDAC1/2 inhibition. In addition, treatment in an orthotopic in vivo model revealed a significantly improved survival. In a heavily pretreated patient suffering from an anaplastic meningioma, oral panobinostat treatment could delay the tumor growth rate. In search of the molecular mechanism underlying a potential intrinsic panobinostat resistance, we identified upregulation of the HDAC8-TGF{beta}-EMT axis in the TO model and subsequent HDAC8 depletion substantially increased the sensitivity to panobinostat. These data highlight the utility of personalized drug screenings on TOs to identify suitable drug targets and inhibitors for a more effective treatment of clinically aggressive meningiomas and help to advance our understanding of counteracting resistance mechanisms. One Sentence SummaryThis study provides strong in vitro, in vivo, ex vivo, and patient evidence for the efficacy of the HDACi panobinostat to treat clinically aggressive meningiomas and uncovered a potential intrinsic resistance mechanism by activation of the HDAC8-TGF{beta}-EMT axis.

cancer biology↗
bioRxiv2024

Ultra-High Dose Rate Helium Ion Beams: First In Vivo Evidence for Neuroprotective FLASH Effect

Ultra-high dose rate radiotherapy with electrons and protons has shown potential for cancer treatment by effectively targeting tumors while sparing healthy tissues (FLASH effect). This study aimed to investigate the potential FLASH sparing effect of ultra-high-dose rate helium ion irradiation, focusing on acute brain injury and subcutaneous tumor response in a preclinical in vivo setting. Raster-scanned helium ion beams were used to compare the effects of standard dose rate (SDR at 0.2 Gy/s) and FLASH (at 141 Gy/s) radiotherapy on healthy brain tissue. Irradiation-induced brain injury was studied in C57BL/6 mice via DNA damage response, using nuclear {gamma}H2AX as a marker for double-strand breaks (DSB). The integrity of neurovascular and immune compartments was assessed through CD31+ microvascular density and activation of microglia/macrophages. Iba1+ ramified and CD68+ phagocytic microglia/macrophages were quantified, along with the expression of inducible nitric oxide synthetase (iNOS). Tumor response to SDR (0.2 Gy/s) and FLASH (250 Gy/s) radiotherapy was evaluated in A549 carcinoma model, using tumor volume and Kaplan-Meier survival as endpoints. The results showed that helium FLASH radiotherapy significantly reduced acute brain tissue injury compared to SDR, evidenced by lower levels of DSB and preserved neurovascular endothelium. Additionally, FLASH radiotherapy reduced neuroinflammatory signals compared to SDR, as indicated by fewer CD68+ iNOS+ microglia/macrophages. FLASH radiotherapy achieved tumor control comparable to that of SDR radiotherapy. This study is the first to report the FLASH sparing effect of raster scanning helium ion radiotherapy in vivo, highlighting its potential for neuroprotection and effective tumor control.

cell biology↗
bioRxiv2023

Spatial and temporal transcriptomics of SHH-medulloblastoma with chromothripsis identifies multiple genetic clones that resist to treatment and lead to relapse

Paediatric medulloblastomas with chromothripsis are characterised by high genomic instability and are among the tumours with the worst prognosis. However, the determinants of their aggressiveness and the molecular makeup of chromothriptic medulloblastoma are not well understood. Here, we applied spatial transcriptomics to profile a cohort of 13 chromothriptic and non-chromothriptic medulloblastomas from the same molecular subgroup. Our data reveal a higher extent of spatial intra-tumour heterogeneity in chromothriptic medulloblastomas, which is associated with increased proliferation and stemness, but lower immune infiltration and differentiation. Spatial mapping of genetic subclones of the same tumour identify a regionally distinct architecture and clone-specific phenotypic features, with distinct degrees of differentiation, proliferation and immune infiltration between clones. We conducted temporal profiling of 11 patient-derived xenografts from chromothriptic medulloblastomas, covering the transition from the minimal residual disease stage to treatment-resistant regrown tumours. In chromothriptic medulloblastoma, an ecosystem of cells from multiple genetic clones resisting treatment and leading to relapse highlighted the importance of multi-clone interplay. Finally, we identified a potential role for tumour microtubes in treatment resistance in chromothriptic medulloblastoma, suggesting cell network communication as a putative target. HighlightsO_ST_ABSBiological insightsC_ST_ABSO_LIMedulloblastomas with chromothripsis are characterised by higher spatial intra-tumour heterogeneity, proliferation and stemness, but lower immune infiltration and differentiation, as compared with non-chromothriptic medulloblastomas C_LIO_LISpatially aware genetic clone assignment identifies phenotypic features such as degree of differentiation, proliferation and immune infiltration enriched in specific clones C_LIO_LICells from distinct genetic clones resist to treatment and give rise to relapse in patient-derived xenografts of medulloblastoma with chromothripsis C_LIO_LITumour microtubes point to putative molecular processes implicated in treatment resistance in chromothriptic medulloblastoma C_LI Technological advancesO_LIValidation of the spatial representation of patient-derived xenograft models, providing novel insights into the faithfulness of such models to study cancer C_LIO_LISpatial mapping of clones based on spatial transcriptomics and copy-number variant profiling C_LI

cancer biology↗
bioRxiv2022

Reprogramming M2-polarized patient-derived glioblastoma associated microglia/macrophages via CSF1R inhibition

Targeting immunosuppressive and protumorigenic glioblastoma-associated macrophages and microglial cells (GAMs) holds great potential to improve patient outcomes. Although CSF1R has emerged as a promising target to reprogram anti-inflammatory M2-like GAMs, relevant treatment data on human, tumor-educated GAMs and innovative patient-derived 3D tumor organoid models to study the influence on adaptive immunity and the effectiveness of treatment in a complex and entirely autologous setting are largely lacking. We performed a comprehensive phenotypical, transcriptional and functional analysis of primary, patient-derived GAMs upon treatment with the CSF1R-targeting drugs PLX3397, BLZ945, and GW2580. The most effective reprogramming of GAMs was observed upon GW2580 treatment, which led to a downregulation of M2-related markers and signaling pathways, while M1-like markers, phagocytosis, and T-cell killing were substantially increased. Moreover, treatment of patient-derived glioblastoma organoids with GW2580 confirmed successful reprogramming together with reduced tumor cell proliferation, indicating that treatment with GW2580 could be an important pillar in the future therapy of GBM.

cancer biology↗
bioRxiv2022

Carbon ion irradiation plus CTLA4 blockade elicits therapeutic immune responses in a murine tumor model

Radiotherapy can act as an in situ vaccine thereby activating tumor-specific immune responses that prevent tumor outgrowth in treated patients. While carbon ion radiotherapy has shown superior biophysical properties over conventional photon irradiation, the immunological effects induced have remained largely uncovered. The combination of radiotherapy with immune checkpoint inhibition (radioimmunotherapy) aims at further enhancement of anti-tumor immunity; however, studies on the immune cell composition in irradiated and distant tumors following radioimmunotherapy with carbon ions are scarce. We have established a bilateral tumor model by time shifted transplantation of murine, Her2+ EO771 tumor cells onto the flanks of immune competent mice followed by selective irradiation of the primal tumor, while sparing the consecutive tumor. We demonstrate that CTLA4-but not PD-L1-based radioimmunotherapy induces complete tumor rejection in our model. Intriguingly, local tumor control caused in situ immunization resulting even in eradication of non-irradiated, distant tumors. Moreover, cured mice were protected against EO771 rechallenge indicative of long lasting, tumor-protective immunological memory. Deconvolution of the treatment induced immunological effects by single cell RNA-sequencing (scRNA-seq) and concomitant flow cytometric analyses revealed in irradiated tumors predominating myeloid cells that developed into distinct tumor-associated macrophage clusters with upregulated expression of TNF and IL1 responsive genes, as well as activation of NK cells. Non-irradiated tumors showed higher frequencies of naive T cells in irradiated mice, which were activated when combined with CTLA4 blockade. In conclusion, radioimmunotherapy with carbon ions plus CTLA4 inhibition reshapes the tumor-infiltrating immune cell composition and can induce complete rejection even of non-irradiated tumors. Our data present a rationale to combine radiotherapy approach with CTLA4 blockade to achieve durable anti-tumor immunity. Evaluation of future radioimmunotherapy approaches should thus not only focus on the immunological impacts at the site of irradiation but should also consider systemic immunological effects that might affect outgrowth of non-irradiated tumors.

immunology↗
bioRxiv2021

GLS-driven glutamine catabolism contributes to prostate cancer radiosensitivity by regulating the redox state, stemness and ATG5-mediated autophagy

Radiotherapy is one of the curative treatment options for localized prostate cancer (PCa). The curative potential of radiotherapy is mediated by irradiation-induced oxidative stress and DNA damage in tumor cells. However, PCa radiocurability can be impeded by tumor resistance mechanisms and normal tissue toxicity. Metabolic reprogramming is one of the major hallmarks of tumor progression and therapy resistance. Here, we found that radioresistant PCa cells and prostate cancer stem cells (CSCs) have a high glutamine demand. Glutaminase (GLS)-driven catabolism of glutamine serves not only for energy production but also for the maintenance of the redox state. Consequently, glutamine depletion or inhibition of critical regulators of glutamine utilization, such as glutaminase (GLS) and the transcription factor MYC results in PCa radiosensitization. On the contrary, we found that a combination of glutamine metabolism inhibitors with irradiation does not cause toxic effects on nonmalignant prostate cells. Glutamine catabolism contributes to the maintenance of CSCs through regulation of the alpha-ketoglutarate (-KG)-dependent chromatin-modifying dioxygenase. The lack of glutamine results in the inhibition of CSCs with a high aldehyde dehydrogenase (ALDH) activity, decreases the frequency of the CSC populations in vivo and reduces tumor formation in xenograft mouse models. Moreover, this study shows that activation of the ATG5-mediated autophagy in response to a lack of glutamine is a tumor survival strategy to withstand radiation-mediated cell damage. In combination with autophagy inhibition, the blockade of glutamine metabolism might be a promising strategy for PCa radiosensitization. High blood levels of glutamine in PCa patients significantly correlate with a shorter prostate-specific antigen (PSA) doubling time. Furthermore, high expression of critical regulators of glutamine metabolism, GLS1 and MYC, is significantly associated with a decreased progression-free survival in PCa patients treated with radiotherapy. Our findings demonstrate that GLS-driven glutaminolysis is a prognostic biomarker and therapeutic target for PCa radiosensitization.

cancer biology↗
bioRxiv2020

High complexity cellular barcoding and clonal tracing reveals stochastic and deterministic parameters of radiation resistance

The impact of functional heterogeneity in response to radiation therapy is poorly understood to the present. It remains elusive whether clonal selection of tumor cells in response to ionizing radiation (IR) is a deterministic or stochastic process. We applied high-resolution lentiviral cellular barcoding for quantitative clonal tracking and deconvolution of clonal dynamics in response to IR. Clonal tracking of over 400.000 HNSCC patient-derived tumor cells and the analyses of over 1500 million sequencing reads in clonogenic survival assays reveals that fractionated IR induced a strong selective pressure for clonal reduction. This significantly exceeded uniform clonal survival probabilities indicative for a strong clone-to clone difference within tumor cell lines. IR induced clonal reduction affected the majority of tumor cells ranging between 96-75% and correlated to the degree of radiation sensitivity. Survival and clonogenicity is characterized by an intensive clonal distortion and dominance of individual tumor cells. Survival to IR is driven by a deterministic clonal selection of a smaller population which commonly survives radiation, while increased clonogenic capacity is a result of clonal competition of cells which have been selected stochastically. A 2-fold increase in radiation resistance results in a 4-fold (p<0.05) higher deterministic clonal selection showing that the ratio of these parameters is amenable to radiation sensitivity which correlates to prognostic biomarkers of HNSCC. Evidence for the existence of a rare subpopulation with an intrinsically radiation resistant phenotype commonly surviving IR was found at a frequency of 0.6-3.3% (p<0.001, FDR 3%). With cellular barcoding we introduce a novel functional heterogeneity associated qualitative readout for tracking dynamics of clonogenic survival in response to radiation. This enables the quantification of intrinsically radiation resistant tumor cells from patient samples and reveals the contribution of stochastic and deterministic clonal selection processes in response to IR.

systems biology↗
bioRxiv2020

The biomedical sensor Cell-Fit-HD4D, reveals individual tumor cell fate in response to microscopic ion deposition.

Here we present the biomedical sensor cell-fluorescent ion track hybrid detector4D (Cell-Fit-HD4D) to reveal individual tumor cell fate in response to microscopic ion deposition in ion beam therapy. The sensor enables long-term monitoring of single tumor cells after clinical ion beam irradiation in combination with single-cell dosimetry. Cell-Fit-HD4D is read out in-situ by conventional optical microscopy. Direct visualization of a clinical ion beam is hereby possible for the first time. The possibility to reveal fate of individual cells from a cell cohort demonstrates that our biomedical sensor clearly differs from conventional experiments that characterize cellular response after radiation on a population level. Cell-Fit-HD4D is therefore used to mimics the clinical situation of a defined tumor depth during tumor treatment by ion beam therapy. Our biomedical sensor is able to provide crucial input for current mechanistic approaches to biophysical modelling of the effect of ionizing radiation on biological matter. In the clinical context, obtaining multi-dimensional physical and biological information on individual tumor cells is an important step to further transform ion beam therapy into a highly precise discipline within oncology.

cancer biology↗
bioRxiv2020

Carbon ion dosimetry on a fluorescent nuclear track detector using widefield microscopy

Fluorescent nuclear track detectors (FNTD) are solid-state dosimeters used in a wide range of dosimetric and biomedical applications in research worldwide. FNTDs are a core but currently underutilized dosimetry tool in the field of radiation biology which are inherently capable of visualizing the tracks of ions used in hadron therapy. The ions that traverse the FNTD deposit their energy according to their linear energy transfer (LET) and transform colour centres to form trackspots around their trajectory. These trackspots have fluorescent properties which can be visualized by fluorescence microscopy enabling a well-defined dosimetric readout with a spatial component indicating the trajectory of individual ions. The current method used to analyse the FNTDs is laser scanning confocal microscopy (LSM). LSM enables a precise localization of track spots in x, y and z however due to the scanning of the laser spot across the sample, requires a long time for large samples. This body of work conclusively shows for the first time that the readout of the trackspots present after 0.5 Gy carbon ion irradiation in the FNTD can be captured with a widefield microscope (WF). The WF readout of the FNTD is a factor [~]10 faster, for an area 2.97 times the size making the method nearly a factor 19 faster in track acquisition than LSM. The dramatic decrease in image acquisition time in WF presents an alternative to LSM in FNTD workflows which are limited by time, such as biomedical sensors which combine FNTDs with live cell imaging.

biophysics↗