Biology subjects

Pajonk, F.

Publications and source records attributed to Pajonk, F..

18 recordsLinked to original sources

bioRxiv2026

Exosome-Mediated Bidirectional Signaling Regulates Glioma Stem-Cell Homeostasis and Radiation-Induced Plasticity

Background: Glioblastoma (GBM) is an aggressive brain malignancy characterized by therapeutic resistance and frequent recurrence. Glioma-initiating cells (GICs), also known as glioma stem cells (GSCs), contribute to these features through self-renewal and resistance to genotoxic stress. Radiation therapy can paradoxically replenish the GIC compartment by inducing stem-like properties in non-stem glioma cells. We investigated whether exosomes mediate bidirectional communication that maintains the balance between GIC and non-stem populations at steady state and following irradiation. Methods: Exosomes were isolated from GIC-enriched gliomaspheres and differentiated monolayer cultures of the patient-derived GBM lines HK-374 and HK-390. Vesicles were characterized by transmission electron microscopy, nanoparticle analysis, and detection of CD63. Recipient cells were exposed to exosomes with or without 4 Gy irradiation. GIC abundance and function were evaluated using a ZsGreen-ornithine decarboxylase degron reporter, sphere-formation assays, and extreme limiting dilution analysis. Exosomal protein cargo was characterized by liquid chromatography-tandem mass spectrometry and Gene Ontology enrichment analysis. Single-cell RNA sequencing was used to evaluate changes in cellular composition upon exosome treatment. Results: Isolated vesicles displayed characteristic exosomal morphology, a mean diameter of 41.6 +/- 14.7 nm, and CD63 expression. Irradiation produced a 12-fold increase in GIC reporter-positive cells among initially reporter-negative differentiated cells. Gliomasphere-derived exosomes significantly and dose-dependently suppressed this radiation-induced phenotype conversion and reduced functional GIC frequency and self-renewal in both patient-derived lines. Conversely, exosomes from GIC-depleted monolayer cultures increased reporter-positive cells two- to three- fold and enhanced the frequency and self-renewal of existing GICs. Proteomic analysis identified 1,796 exosomal proteins, including 336 differentially abundant candidates. Gliomasphere-derived exosomes were enriched in proteins associated with translation, RNA binding, actin organization, cytoskeletal regulation, and intracellular trafficking. Monolayer-derived exosomes were enriched in extracellular-matrix and stem-cell-niche components, including NID2, LAMA5, LAMB1, LAMB2, LAMC1, THBS1, TGFBI, IQGAP3, and APOE. Single-cell transcriptomic analysis showed that gliomasphere-derived exosomes prevented the radiation-induced expansion of neural progenitor-like cells, consistent with suppression of an induced stem-like state. Treatment of gliomaspheres with monolayer-derived exosomes left their overall cellular composition largely but enriched MYC-target, E2F-target, and oxidative-phosphorylation programs, suggesting that increased sphere formation may partly reflect enhanced proliferative capacity. Conclusions: GBM cells use exosomes to establish a bidirectional feedback circuit between stem-like and differentiated tumor-cell compartments. GIC-derived exosomes constrain radiation-induced conversion of non-stem glioma cells into GICs, whereas differentiated-cell-derived exosomes promote a niche that supports GIC maintenance and self-renewal, potentially through expansion of a mixed-vascular-like population containing neurovascular progenitors. Whether exosomal IQGAP3 contributes to the expansion of this GIC population remains to be determined. These findings identify exosome-mediated intercellular communication as a potential mechanism regulating GBM cellular homeostasis, treatment resistance, and recurrence.

neuroscience↗

bioRxiv2026

Temporal Mapping of Radiation-Induced Neural Injury and Mitigation in Human Cortical Organoids

BackgroundRadiation therapy is a standard-of-care oncological treatment for central nervous system (CNS) malignancies. However, as survival outcomes improve, radiation-induced injury to normal brain tissue has increased in clinical significance. CNS radiation injury is a delayed, multifactorial process characterized by impaired neurogenesis, reactive gliosis, and persistent functional deficits. Mechanistic exploration and development of effective radiation mitigators have been limited by the lack of scalable, human-relevant models. MethodsMature human iPSC-derived cortical organoids were exposed to single-dose or clinically relevant fractionated radiation (5 x 2 Gy). DNA damage, apoptosis, and growth dynamics were assessed longitudinally. Structural organization, synaptic integrity, and neuroinflammatory responses were evaluated by immunofluorescence and real-time PCR. Transcriptomic profiling was performed at 72 hours and 2 weeks after fractionated radiation to capture acute and delayed effects. Two candidate radiation mitigators, NSPP and amisulpride, were tested for their therapeutic effects within the organoid system. ResultsCortical organoids exhibited partial recovery following single doses up to 4 Gy or fractioned irradiation. Transcriptomic analyses revealed that radiation not only reduced overall cell viability but also reshaped lineage trajectories, characterized by depletion of neural stem/progenitor populations, loss of neuronal identity, enhanced gliogenesis, increased inflammatory cytokines, and disrupted cortical layering and synaptic integrity. Treatment with NSPP or amisulpride attenuated injury-associated transcriptional and structural alterations. ConclusionHuman cortical organoids recapitulate key features of radiation-induced neural injury, recovery, and therapeutic modulation, providing a robust, scalable, and human-relevant platform for studying CNS radiation biology and preclinical screening of candidate radiation mitigators. Key pointsO_LIHuman iPSC-derived cortical organoids enable study of human CNS radiation responses. C_LIO_LIOrganoids recover after single-dose and fractionated radiation relevant to clinical exposure. C_LIO_LIThe platform supports scalable, human-relevant testing of radiation mitigation strategies. C_LI

cell biology↗

bioRxiv2025

Targeting Radiation-Induced Glioma-Initiating Cells in Patient-Derived Glioblastoma

BackgroundGlioblastoma (GB) is a highly aggressive and treatment-resistant brain cancer with poor prognosis. Surgical resection followed by radiotherapy (RT) with the chemotherapeutic, temozolomide (TMZ), is the standard GB treatment; yet recurrence often occurs. GB is organized hierarchically with a small population of radiation-resistant glioma-initiating cells (GICs) that self-renew and drive tumor growth. Importantly, RT can induce a subset of cells from non-tumor-initiating into glioma-initiating cells (iGICs). Both GICs and iGICs contribute to tumor recurrence and therapy resistance. Thus, without effective elimination of non-tumorigenic GB and prevention or targeting of GICs, a cure is unlikely. The objective of this study is to identify small molecules that block RT-induced phenotypic conversion to occur. MethodWe conducted a high-throughput screen of NCIs Cancer Therapy Evaluation Program (CTEP) compounds with evidence for crossing the blood-brain-barrier. To identify "stemness" or reprogramming of cells, we transduced GB cell lines representing each TCGA subtype to express a fluorescent reporter for proteasomal activity that distinguishes non-tumor-initiating cells from GICs. We tested CTEP agents at 10 different concentrations in combination with radiation. ResultsOur results identified selumetinib as a candidate compound that effectively prevents radiation-induced phenotype conversion. Furthermore, in combination with radiation, selumetinib decreased stem cell maintenance in GICs with differential effects on viability in non-tumorigenic cells. ConclusionTaken together, these findings suggest that repurposing FDA-approved compounds alongside current therapies may effectively target the cellular and molecular heterogeneity of GB--and because these agents are already clinically approved, this approach can be rapidly implemented in the clinic.

cancer biology↗

bioRxiv2025

Repurposing Quetiapine as an Adjuvant Therapeutic Agent for Triple-Negative Breast Cancer

PurposeTriple-negative breast cancer (TNBC) lacks actionable molecular targets, so treatment primarily relies on cytotoxic chemotherapy and radiotherapy, yet relapse, resistance, and metastasis still drives poor long-term survival. Dopamine signaling has recently been linked to tumor aggressiveness, and dopaminel1lreceptor antagonists have shown preclinical benefit in other cancers. We therefore evaluated quetiapine (QTP), an FDAl1lapproved DRD2/DRD3 antagonist, as a therapeutic adjunct in TNBC. MethodsSUM159l1lPT, BTl1l549, and MDAl1lMBl1l231 cells were treated with QTP alone or combined with radiation or standard agents (doxorubicin, paclitaxel, 5l1lfluorouracil). Clonogenic and mammosphere assays measured proliferative and selfl1lrenewal potential. Annexin V/propidiuml1liodide flow cytometry quantified apoptosis, and {gamma}l1lH2AX immunofluorescence tracked DNA doublel1lstrand breaks and repair kinetics. Transwell assays assessed migration of untreated bulk cells and radiationl1lsurviving subclones. ResultsQTP significantly reduced clonogenicity and self-renewal in all TNBC models tested, both alone and in combination with radiation or chemotherapy. In apoptosis assays, QTP treatment induced a marked increase in early and late apoptotic cell populations. QTP also promoted DNA double-strand break formation and delayed repair, as indicated by persistent {gamma}-H2AX foci at 24 hours post-treatment. Additionally, QTP impaired the migratory capacity of both untreated and radiation-surviving cells. Combination treatments with QTP and doxorubicin produced synergistic effects, resulting in complete loss of colony-forming ability and mammosphere formation. ConclusionThe data presented support the repurposing of quetiapine as an adjuvant therapeutic agent alongside radiotherapy and/or chemotherapy in TNBC. By targeting apoptosis, DNA repair, and cancer cell migration, QTP offers a novel, multi-faceted approach to improve outcomes in this high-risk breast cancer subtype.

cancer biology↗

bioRxiv2025

Design and Biological Activity of a Novel Brain Penetrant Urea Compound Against Glioblastoma

Glioblastoma (GBM) remains the most lethal primary brain tumor, largely due to therapy-resistant glioma stem cells (GSCs) and the ability of non-stem cells to dedifferentiate under therapeutic pressure. We developed MXC-017, a novel urea-based compound that crosses the blood-brain-barrier, directly targets GSCs, and prevents radiation-induced GSC formation. Using click chemistry pull-down and mass spectrometry, we identified vimentin as the target of MXC-017, further validated by in silico docking. Global transcriptomic profiling (bulk RNA-seq) and single-cell RNA-seq analyses revealed MXC-017s efficacy with minimal off-target effects, supported by metabolic and kinome assays. Normal cell toxicity was negligible in fibroblasts, microglia, astrocytes, and murine neural progenitors. Maximum tolerated dose was identified and we observed significantly extended median survival in 17 PDOX GBM models when treated with MXC-017 plus radiation, benchmarked against standard-of-care temozolomide. These findings underscore the therapeutic potential of vimentin-targeting agents to overcome radiation resistance and improve outcomes for GBM patients. Statement of SignificanceGlioblastomas distinctive nature and the blood-brain barrier hamper therapies targeting therapy-resistant GSCs. We developed a novel urea-based agent that crosses the barrier, targets GSCs, and prevents radiation-induced GSC formation. With minimal off-target effects, reduced toxicity, and superior survival in PDOX models, it offers potential to improve outcome in GBM.

neuroscience↗

bioRxiv2025

Combined quetiapine and radiation therapy approach to treat mesothelioma-initiating cells and increase survival in a mouse model of mesothelioma

IntroductionMalignant pleural mesothelioma (MPM) is a rare thoracic cancer associated with poor prognosis and low survival rates. In solid cancers, repurposed dopamine receptor antagonists have been shown to have anti-cancer effects. Moreover, in combination with radiotherapy, quetiapine (QTP), a dopamine (D) 2/3 receptor antagonist, has been shown to interfere with self-renewal capacity in glioma-initiating cells and increase survival in mouse models of glioblastoma. In this study we explore combined treatment effects in MPM. MethodsUsing mesothelioma cell lines, MSTO-211H, H2052, and H2452, and a MSTO-211H-derived orthotopic xenograft mouse model of MPM we examined how QTP combined with radiation affects mesothelioma-initiating cells (MICs) in vitro and survival in vivo. Subsequently, bulk and single cell RNA sequencing was used to characterize the transcriptomic landscape of MSTO-211H treated with combined radiation and QTP. ResultsWe demonstrate that combining QTP with radiation reduces MIC self-renewal capacity and stem cell frequency. In vivo, this combination therapy significantly extends the median survival of mesothelioma-bearing mice. Clonogenic survival assays revealed that QTP does not enhance radiosensitivity in the tested mesothelioma cell lines. Sequencing data revealed, combined treatment downregulated cell cycle and proliferation pathways, depleted cancer stem cells, and increased cellular senescence. ConclusionTaken together, our study highlights the therapeutic potential of radiation with QTP in the treatment of MPM.

cancer biology↗

bioRxiv2024

Targeting Innate Immune Signaling in Glioma-Initiating Cells Impairs Self-Renewal and Radiation-Induced Cellular Plasticity

Organisms constantly face environmental stressors that threaten their cellular and genomic integrity. In their response, pathogen-associated molecular patterns (PAMPs) and/or damage-associated molecular patterns (DAMPs) are detected by pattern recognition receptors (PRRs) and trigger the innate immune response. In this study we tested the hypothesis that DAMPs contribute to radiation-induced cellular plasticity in Glioblastoma (GBM). GBM is known to be organized hierarchically with a small number of glioma-initiating cells (GICs) driving treatment resistance and recurrences. Using patient-derived GBM specimens, we employed sphere forming capacity assays and in vitro extreme limiting dilution assays to examine how innate immune receptor signaling impacts the maintenance and self-renewal of GICs. By leveraging an imaging system for putative GICs we determined de novo induction of GICs from non-stem glioma cells. We find that GIC maintenance after irradiation is mediated by cGAS-independent STING signaling, possibly involving signaling through TLR4 and TLR9. Induction of radiation-induced plasticity involves TLR3 signaling, with potential roles for other receptors and processes modulated by MyD88. These findings suggest that targeting innate immune signaling could prevent radiation-induced cellular plasticity for potential therapeutic benefit.

cancer biology↗

bioRxiv2024

Transcriptome of the murine duodenum during recovery after a lethal dose of total body irradiation

In the aftermath of 9/11, the radiobiology community sought novel radiation mitigators capable of preventing death when administered 24 hours or later after exposure to lethal ionizing radiation. The survival and expansion of normal stem cells are crucial for restoring tissue integrity in time to prevent mortality. While FDA-approved drugs for acute radiation syndrome primarily target the hematopoietic system, restoring the integrity of the intestinal lining is equally important for survival. However, the radiation response of the intestinal stem cell (ISC) population and its niche environment is not as well understood as that of the bone marrow. The aim of this study was to explore early transcriptomic changes in the small intestine after a lethal dose of total body irradiation (TBI), and during subsequent recovery. C3H/Sed/Kam mice were irradiated with a TBI dose of 16 Gy, the published LD70/10. The compound 1-[(4-Nitrophenyl)sulfonyl]-4-phenylpiperazine (NSPP) was administered 24 hours post-irradiation. RNAs from the proximal duodenum were extracted at 28, 72, and 96 hours post-irradiation and subjected to RNA-sequencing. Differentially expressed genes were analyzed using gene-set enrichment analysis. Radiation induced significant transcriptomic changes known to precede the death of lymphatic endothelial and epithelial cells. Upregulation of Lgr5+ ISC gene signature was observed during recovery. NSPP treatment further amplified the activation of ISC-associated genes and other regenerative markers. Notably, gene Psrc1 showed strong activation throughout the recovery process, highlighting its potential role in this regenerative response. These findings suggest additional points of intervention for radiation mitigation in the intestines beyond targeting programmed cell death.

developmental biology↗

bioRxiv2024

Radiation-Induced Cellular Plasticity: A Strategy for Combatting Glioblastoma

Glioblastoma is the deadliest brain cancer in adults and almost all patients succumb to the tumor. While surgery followed by chemo-radiotherapy significantly delays disease progression, these treatments do not lead to long-term tumor control and targeted therapies or biologics have so far failed to further improve survival. Utilizing a transient radiation-induced state of multipotency we used the adenylcyclase activator forskolin to alter the cellular fate of glioma cells in response to radiation. The combined treatment induced the expression of neuronal markers in glioma cells, reduced proliferation and led to a distinct gene expression profile. scRNAseq revealed that the combined treatment forced glioma cells into a microglia- and neuron-like phenotypes. In vivo this treatment led to a loss of glioma stem cells and prolonged median survival in mouse models of glioblastoma. Collectively, our data suggest that revisiting a differentiation therapy with forskolin in combination with radiation could lead to clinical benefit.

cancer biology↗

bioRxiv2023

Activation of the mevalonate pathway in response to anti-cancer treatments drives glioblastoma recurrences through activation of Rac-1

Glioblastoma is the deadliest adult brain cancer. Under the current standard of care almost all patients succumb to the disease and novel treatments are urgently needed. Dopamine receptor antagonists have been shown to target cancer cell plasticity in GBM and repurposing these FDA-approved drugs in combination with radiation improves the efficacy of radiotherapy in glioma models. In cells surviving this combination treatment the mevalonate pathway is upregulated at the transcriptional and functional level. Here we report that glioblastoma treatments that converge in the immediate early response to radiation through activation of the MAPK cascade universally upregulate the mevalonate pathway and increase stemness of GBM cells through activation of the Rho-GTPase Rac-1. Activation of the mevalonate pathway and Rac-1 is inhibited by statins, which leads to improved survival in mouse models of glioblastoma when combined with radiation and drugs that target the glioma stem cell pool and plasticity of glioma cells.

neuroscience↗

bioRxiv2023

Effects of Dopamine Receptor Antagonists and Radiation on Mouse Neural Stem/Progenitor Cells

BackgroundDopamine receptor antagonists are psychotropic drugs that have been originally developed against psychiatric disorders. We recently identified dopamine receptor antagonists as potential anti-cancer agents and some have entered clinical trials against glioblastoma. Radiotherapy is known to cause cognitive impairment in patients receiving cranial irradiation through the elimination of neural stem/progenitor cells and subsequent loss of neurogenesis. MethodsUsing transgenic mice that report the presence of neural stem/progenitor cells through Nestin promoter-driven expression of enhanced green fluorescent protein, the effects of dopamine receptor antagonists alone or in combination with radiation on murine neural stem/progenitor cells were assessed in sphere-formation assays, flow cytometry and immunofluorescence in vitro and in vivo. ResultsWe report that several dopamine receptor antagonists show sex-dependent effects on neural stem/progenitor cells both in vitro and in vivo. Hydroxyzine, trifluoperazine, amisulpride, nemonapride or quetiapine alone or in combination with radiation significantly increased the number of neural stem/progenitor cells in female neurospheres but not in male mice. Dopamine receptor antagonists either protected neural stem/progenitor cells from radiation or expanded the stem cell pool, thus indicating that this combination therapy against glioblastoma will not increase radiation-induced cognitive decline through increasing elimination of neural stem/progenitor cells and subsequent loss of neurogenesis. ConclusionsWe conclude that a therapeutic window for dopamine receptor antagonists in combination with radiation potentially exist, making it a novel combination therapy against glioblastoma. Normal tissue toxicity of this combination potentially differs depending on age and sex and should be taken into consideration when designing clinical trials. Key Points- Neural stem/progenitor cells show sex-dependent sensitivity to dopamine receptor antagonists - Dopamine receptor antagonists active against GBM increase Neural stem/progenitor cells counts Importance of the StudyCombination therapy of dopamine receptor antagonists with radiation have entered clinical trials against glioblastoma but the normal tissue toxicity of this combination has not been fully explored yet. Here we present evidence that some dopamine receptor antagonists show sex-dependent effects on neural stem/progenitor cells either by protecting neural stem/progenitor cells from radiation or inducing an expansion of the stem cell pool, suggesting that this combination therapy against glioblastoma will not increase radiation-induced cognitive decline through increasing elimination of neural stem/progenitor cells and subsequent loss of neurogenesis. Normal tissue toxicity of this combination potentially differs depending on age and sex and should be further explored in clinical trials.

neuroscience↗

bioRxiv2022

NADPH oxidase promotes glioblastoma radiation resistance in a PTEN-dependent manner

AimsThe goal of this study was to determine whether NADPH oxidase (NOX)-produced reactive oxygen species enhances brain tumor growth of glioblastoma (GBM) under hypoxic conditions and during radiation treatment. ResultsExogenous ROS promoted brain tumor growth in gliomasphere cultures that expressed functional PTEN, but not in tumors that were PTEN deficient. Hypoxia induced the production of endogenous cytoplasmic ROS and tumor cell growth via activation of NOX. NOX activation resulted in oxidation of PTEN and downstream Akt activation. Radiation also promoted ROS production via NOX which, in turn, resulted in cellular protection that could be abrogated by knockdown of the key NOX component, p22. Knockdown of p22 also inhibited tumor growth and enhanced the efficacy of radiation in PTEN-expressing GBM cells. InnovationWhile other studies have implicated NOX function in GBM models, these studies demonstrate NOX activation and function under physiological hypoxia and following radiation in GBM, two conditions that are seen in patients. NOX plays an important role in a PTEN-expressing GBM model system, but not in PTEN-non-functional systems and provide a potential, patient-specific therapeutic opportunity. ConclusionsThis study provides a strong basis for pursuing NOX inhibition in PTEN-expressing GBM cells as a possible adjunct to radiation therapy.

cancer biology↗

bioRxiv2021

Radiation-induced reprogramming drives glioma vascular transdifferentiation and tumor recurrence

Treatment-refractory glioma stem and tumor cells exhibit phenotypic plasticity driving recurrence, but the underlying molecular mechanisms remain to be elucidated. Here, we employed single-cell and whole transcriptomic analyses to discover that radiation induces a dynamic shift in functional states of glioma cells allowing for acquisition of vascular endothelial-like and pericyte-like cell phenotypes. These vascular-like cells provide a trophic niche to promote proliferation of irradiated glioma cells, and their selective depletion results in reduced tumor growth post-treatment in vivo. Mechanistically, the acquisition of vascular-like phenotype is driven by increased chromatin accessibility and H3K27 acetylation in specific vascular gene regions post-treatment. Blocking P300 histone acetyltransferase activity reverses the epigenetic changes induced by radiation, and inhibits the phenotypic transition and tumor growth. Our findings highlight an important role for P300 histone acetyltransferase in treatment-induced plasticity and opens a new therapeutic avenue for preventing glioma recurrence. SignificanceOur study demonstrates that radiation therapy promotes glioma resistance by inducing vascular-like phenotypes in GSC that, in turn, aid in proliferation of the remaining tumor cells. This phenotype switch is mediated by P300 HAT, and inhibition of this enzyme is a potential therapeutic target for preventing glioma recurrence following radiation.

cancer biology↗

bioRxiv2020

Synergistic Effects of the DRD2/3 Antagonist ONC201 and Radiation in Glioblastoma

BackgroundGlioblastoma (GBM) is the deadliest of all brain cancers in adults. The current standard-of-care is surgery followed by radiotherapy and temozolomide, leading to a median survival time of only 15 months. GBM are organized hierarchically with a small number of glioma-initiating cells, responsible for therapy resistance and tumor recurrence, suggesting that targeting glioma-initiating cells could improve treatment response. ONC201 is a first-in-class anti-tumor agent with clinical efficacy in some forms of high-grade gliomas. Here we test its efficacy against GBM in combination with radiation. MethodsUsing patient-derived GBM lines and mouse models of GBM we test the effects of radiation and ONC201 on GBM self - renewal in vitro and survival in vivo. A possible resistance mechanism is investigated using RNA-Sequencing. ResultsTreatment of GBM cells with ONC201 reduced self-renewal, clonogenicity and cell viability in vitro. ONC201 exhibited anti-tumor effects on radioresistant GBM cells indicated by reduced self-renewal in secondary and tertiary glioma spheres. Combined treatment with ONC201 and radiation prolonged survival in syngeneic and patient-derived orthotopic xenograft mouse models of GBM. Subsequent transcriptome analyses after combined treatment revealed shifts in gene expression signatures related to quiescent GBM populations, GBM plasticity, and GBM stem cells. ConclusionsOur findings suggest that combined treatment with the DRD2/3 antagonist ONC201 and radiation improves the efficacy of radiation against GBM in vitro and in vivo through suppression of GICs without increasing toxicity in mouse models of GBM. A clinical assessment of this novel combination therapy against GBM is further warranted. Key points- Combined treatment of ONC201 and radiation exhibit anti-tumor effects on cells from primary and recurrent GBM - Combined treatment significantly prolongs survival in vivo - Combined treatment potentially targets the quiescent GBM cell population Importance of the StudyThe survival rates for patients with GBM are unacceptably low and novel treatment approaches are needed. This study provides evidence that a combination of radiation and the dopamine receptor antagonist ONC201 significantly prolongs survival in mouse models of glioma.

neuroscience↗

bioRxiv2020

Tumor Necrosis Factor Receptor Signaling Modulates Carcinogenesis in a Mouse Model of Breast Cancer

Proinflammatory conditions have long been associated with mammary carcinogenesis and breast cancer progression. The underlying mechanisms are incompletely understood but signaling of TNF through its receptors TNFR1 and TNFR2 is a major mediator of inflammation in both, obesity and in the response of tissues to radiation, two known risk factors for the development of breast cancer. Using the MMTV-Wnt1 mouse model for spontaneous breast cancer and knockout mice for TNFR1 and TNFR2 we report that loss of a TNFR2 allele leads to ductal hyperplasia in the mammary gland with increased numbers of mammary epithelial stem cell and terminal endbuds. Furthermore, that loss of one TNFR2 allele increases the incidence of breast cancers in MMTV-Wnt1 mice and results in tumors with a more aggressive phenotype and metastatic potential. The underlying mechanisms include a preferential activation of canonical NF-{kappa}B signaling pathways and autocrine production of TNF. Analysis of the TCGA dataset indicated inferior overall survival for patients with down-regulated TNFR2 expression. We conclude, that imbalances in TNFR signaling promote the development and progression of breast cancer, indicating that selective agonists of TNFR2 could potentially modulate the risk for breast cancer in high-risk populations. Significance StatementOver the past four decades the treatment results for patients suffering from breast cancer have constantly improved, leaving breast cancer prevention as an important frontier against the second leading cause of cancer death in the United States. Obesity has become a national health crisis and is a known proinflammatory risk factor for breast cancer. Our study describes a previously unknown aspect of proinflammatory signaling on breast cancer development and progression, thus suggesting novel potential targets to modulate the incidence of the disease.

cancer biology↗

bioRxiv2020

Combined Treatment with Dopamine Receptor Antagonists and Radiation Creates a Metabolic Vulnerability in Mouse Models of Glioblastoma

BackgroundGlioblastoma is the deadliest brain tumor in adults and the standard-of-care consists of surgery followed by radiation and treatment with temozolomide. Overall survival times for patients suffering from glioblastoma are unacceptably low indicating an unmet need for novel treatment options. MethodsUsing patient-derived glioblastoma lines and mouse models of glioblastoma we test the effect of radiation and the dopamine receptor antagonist on glioblastoma self-renewal in vitro and survival in vivo. A possible resistance mechanism is investigated using RNA-Sequencing. ResultsTreatment of glioma cells with the dopamine receptor antagonist quetiapine reduced glioma cell self-renewal in vitro and combined treatment of mice with quetiapine and radiation prolonged the survival of glioma-bearing animals. The combined treatment induced the expression of genes involved in cholesterol biosynthesis. This rendered the tumors vulnerable to simultaneous treatment with atorvastatin and further significantly prolonged the survival of the animals. ConclusionsOur results indicate high efficacy of a triple combination of quetiapine, atorvastatin and radiation against glioblastoma without increasing the toxicity of radiation. With both drugs readily available for clinical use our study could be rapidly translated into a clinical trial.

neuroscience↗

bioRxiv2020

1--4-phenylpiperazine Treatment After Brain Irradiation Preserves Cognitive Function in Mice

BackgroundNormal tissue toxicity to the CNS is an inevitable consequence of a successful radiotherapy of brain tumors or cancer metastases to the CNS. Cranial irradiation commonly leads to neurocognitive deficits that manifest months or years after treatment. Mechanistically, radiation-induced loss of neural stem/progenitor cells, neuro-inflammation and de-myelinization are contributing factors that lead to progressive cognitive decline. MethodsThe effects of Compound #5 on irradiated murine neurospheres, microglia cells and patients-derived gliomaspheres were assessed in sphere-formation assays, flow cytometry and IL-6 ELISAs, Activation of the Hedgehog pathway was studied by qRT-PCR. The in vivo effects of Compound #5 were analyzed using flow cytometry, sphere-formation assays, immune-histochemistry, behavioral testing and an intracranial mouse model of glioblastoma. ResultsWe report that 1-[(4-Nitrophenyl)sulfonyl]-4-phenylpiperazine (Compound #5) mitigates radiation-induced normal tissue toxicity in the brains of mice. Compound #5 treatment significantly increased the number of neural stem/progenitor cells after brain irradiation in female animals, inhibited radiation-induced microglia activation and expression of the pro-inflammatory cytokine interleukin-6. Behavioral testing revealed that treatment with Compound #5 after radiotherapy successfully mitigates radiation-induced decline in motor, sensory and memory function of the brain. In mouse models of glioblastoma, Compound #5 showed no toxicity and did not interfere with the growth-delaying effects of radiation. ConclusionsWe conclude that Compound #5 has the potential to mitigate cognitive decline in patients undergoing partial or whole brain irradiation without promoting tumor growth and that the use of this compound as a radiation mitigator of radiation late effects on the CNS warrants further investigation. Importance of the StudySuccessful radiotherapy of CNS malignancies inevitably lead to cognitive decline in cancer survivors and treatment options to mitigate this side effect are limited. We present evidence that a piperazine compound can prevent cognitive decline in mice after total brain irradiation without compromising the antitumor effect of radiation, suggesting that this compound could be used to mitigate radiation side effects in brain tumor patients undergoing radiotherapy.

neuroscience↗

bioRxiv2019

The Dopamine Receptor Antagonist TFP Prevents Phenotype Conversion and Improves Survival in Mouse Models of Glioblastoma

Glioblastoma (GBM) is the deadliest adult brain cancer and all patients ultimately succumb to the disease. Radiation therapy (RT) provides survival benefit of 6 months over surgery alone but these results have not improved in decades. We report that radiation induces a glioma-initiating cell phenotype and we have identified trifluoperazine (TFP) as a compound that interferes with this phenotype conversion. TFP caused loss of radiation-induced Nanog mRNA expression, activation of GSK3 with consecutive post-translational reduction in p-Akt, Sox2 and {beta}-catenin protein levels. TFP did not alter the intrinsic radiation sensitivity of glioma-initiating cells (GICs). Continuous treatment with TFP and a single dose of radiation reduced the number of GICs in vivo and prolonged survival in syngeneic and patient-derived orthotopic xenograft (PDOX) mouse models of GBM. Our findings suggest that combination of a dopamine receptor antagonist with radiation enhances the efficacy of RT in GBM by preventing radiation-induced phenotype conversion of radiosensitive non-GICs into treatment resistant, induced GICs. SignificanceGBM is the most common and most deadly adult brain cancer. The current standard-of-care is surgery followed by RT and temozolomide, which results in a median survival time of only 15 months. The efficacy of chemotherapies and targeted therapies in GBM is very limited because most of these drugs do not pass the blood-brain-barrier. Ultimately, all patients succumb to the disease. Our study describes radiation-induced cellular plasticity as a novel resistance mechanism in GBM. We identified a dopamine receptor antagonist as a readily available, FDA-approved drug known to penetrate the blood-brain-barrier which prevents phenotype conversion of glioma cells into glioma-initiating cells and prologs survival in mouse models of GBM, thus suggesting that it will improve the efficacy of RT without increasing toxicity.

neuroscience↗