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Despite advances in multimodal therapy approaches such as resection, chemotherapy and radiotherapy, the overall survival of patients with grade 4 glioblastoma (GBM) remains extremely poor (average survival time <2 years). Altered lipid metabolism, which increases fatty acid synthesis and thereby contributes to radioresistance in GBM, is a hallmark of cancer. Therefore, we explored the radiosensitizing effect of the clinically approved, lipid-lowering drug fenofibrate (FF) in different GBM cell lines (U87, LN18). Interestingly, FF (50 μM) significantly radiosensitizes U87 cells by inducing DNA double-strand breaks through oxidative stress and impairing mitochondrial membrane integrity, but radioprotects LN18 cells by reducing the production of reactive oxygen species (ROS) and stabilizing the mitochondrial membrane potential. A comparative protein and lipid analysis revealed striking differences in the two GBM cell lines: LN18 cells exhibited a significantly higher membrane expression density of the fatty acid (FA) cluster protein transporter CD36 than U87 cells, a higher expression of glycerol-3-phosphate acyltransferase 4 (GPAT4) which supports the production of large lipid droplets (LDs), and a lower expression of diacylglycerol O-acyltransferase 1 (DGAT1) which regulates the formation of small LDs. Consequently, large LDs are predominantly found in LN18 cells, whereas small LDs are found in U87 cells. After a combined treatment of FF and irradiation, the number of large LDs significantly increased in radioresistant LN18 cells, whereas the number of small LDs decreased in radiosensitive U87 cells. The radioprotective effect of FF in LN18 cells could be associated with the presence of large LDs, which act as a sink for the lipophilic drug FF. To prevent uptake of FF by large LDs and to ameliorate its function as a radiosensitizer, FF was encapsulated in biomimetic cell membrane extracellular lipid vesicles (CmEVs) which alter the intracellular trafficking of the drug. In contrast to the free drug, CmEV-encapsulated FF was predominantly enriched in the lysosomal compartment, causing necrosis by impairing lysosomal membrane integrity. Since the stability of plasma and lysosomal membranes is maintained by the presence of the stress-inducible heat shock protein 70 (Hsp70) which has a strong affinity to tumor-specific glycosphingolipids, necrosis occurs predominantly in LN18 cells having a lower membrane Hsp70 expression density than U87 cells. In summary, our findings indicate that the lipid metabolism of tumor cells can affect the radiosensitizing capacity of FF when encountered either as a free drug or as a drug loaded in biomimetic lipid vesicles., Competing Interests: Declaration of competing interest V.N. is a founder and equity owner of Maurus OY, sThesis GmbH, iThera Medical GmbH, Spear UG and I3 Inc. No conflicts of interest are declared by any of the other authors., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Purpose: Mesenchymal stem cells (MSC) have emerged as cellular-based vehicles for the delivery of therapeutic genes in cancer therapy based on their inherent tumor-homing capability. As theranostic gene, the sodium iodide symporter (NIS) represents a successful target for noninvasive radionuclide-based imaging and therapy. In this study, we applied genetically engineered MSCs for tumor-targeted NIS gene transfer in experimental glioblastoma (GBM)-a tumor with an extremely poor prognosis., Experimental Design: A syngeneic, immunocompetent GL261 GBM mouse model was established by subcutaneous and orthotopic implantation. Furthermore, a subcutaneous xenograft U87 model was used. Bone marrow-derived MSCs were stably transfected with a NIS-expressing plasmid driven by the constitutively active cytomegalovirus promoter (NIS-MSC). After multiple or single intravenous injection of NIS-MSCs, tumoral iodide uptake was monitored in vivo using 123I-scintigraphy or 124I-PET. Following validation of functional NIS expression, a therapy trial with 131I was performed on the basis of the most optimal application regime as seen by 124I-PET imaging in the orthotopic approach., Results: A robust tumoral NIS-specific radionuclide accumulation was observed after NIS-MSC and radioiodide application by NIS-mediated in vivo imaging. NIS immunofluorescence staining of GBM and non-target tissues showed tumor-selective MSC homing along with NIS expression. Application of therapeutically effective 131I led to significantly delayed tumor growth and prolonged median survival after NIS-MSC treatment as compared with controls., Conclusions: A strong tumor-selective recruitment of systemically applied MSCs into GBM was found using NIS as reporter gene followed by successful therapeutic application of radioiodide demonstrating the potential use of NIS-based MSCs as therapy vehicles as a new GBM therapy approach., (©2022 American Association for Cancer Research.)

The major stress-inducible 70 kDa heat shock (stress) protein 70 (Hsp70) is frequently overexpressed in highly aggressive tumor cells and thus might serve as a tumor-specific biomarker of aggressive disease and/or therapeutic resistance. We have previously shown that, in contrast to normal cells, tumor cells present Hsp70 on their plasma membrane. In order to elucidate the role of intracellular, membrane-bound and extracellular Hsp70 as a potential tumor biomarker in cancer, herein we describe protocols for the staining of cytosolic Hsp70 in tumor formalin-fixed paraffin-embedded (FFPE) sections from patients with glioblastoma multiforme using immunohistochemistry, for detecting the expression of plasma membrane-bound Hsp70 by a range of cancer-derived cells using multi-parametric flow cytometry using the cmHsp70.1 monoclonal antibody (mAb) and for the measurement of free and vesicular-associated Hsp70 in the circulation of patients with cancer using a unique enzyme-linked immunosorbent assay (ELISA)., (© 2023. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: Superparamagnetic iron oxide nanoparticles (SPIONs) have displayed multifunctional applications in cancer theranostics following systemic delivery. In an effort to increase the therapeutic potential of local therapies (including focal hyperthermia), nanoparticles can also be administered intratumorally. Therefore, the development of a reliable pharmacokinetic model for the prediction of nanoparticle distribution for both clinically relevant routes of delivery is of high importance., Materials and Methods: The biodistribution of SPIONs (of two different sizes - 130 nm and 60 nm) radiolabeled with zirconium-89 or technetium-99m following intratumoral or intravenous injection was investigated in C57/Bl6 mice bearing subcutaneous GL261 glioblastomas. Based on PET/CT biodistribution data, a novel pharmacokinetic model was established for a better understanding of the pharmacokinetics of the SPIONs after both administration routes., Results: The PET image analysis of the nanoparticles (confirmed by histology) demonstrated the presence of radiolabeled nanoparticles within the glioma site (with low amounts in the liver and spleen) at all investigated time points following intratumoral injection. The mathematical model confirmed the dynamic nanoparticle redistribution in the organism over a period of 72 h with an equilibrium reached after 100 h. Intravenous injection of nanoparticles demonstrated a different distribution pattern with a rapid particle retention in all organs (particularly in liver and spleen) and a subsequent slow release rate., Conclusion: The mathematical model demonstrated good agreement with experimental data derived from tumor mouse models suggesting the value of this tool to predict the real-time pharmacokinetic features of SPIONs in vivo. In the future, it is planned to adapt our model to other nanoparticle formulations to more precisely describe their biodistribution in in vivo model systems., Competing Interests: The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results., (© 2020 Klapproth et al.)

Heat shock protein 70 (Hsp70) which is expressed on the plasma membrane of highly aggressive tumors including non-small cell lung carcinoma and glioblastoma multiforme serves as a target for Hsp70-targeting NK cells. Herein, we aimed to investigate the antitumor effects of a combined therapy consisting of ex vivo Hsp70-peptide TKD/IL-2-activated NK cells in combination with mouse/human anti-PD-1 antibody in a syngeneic glioblastoma and a xenograft lung cancer mouse model. Mice with membrane Hsp70 positive syngeneic GL261 glioblastoma or human xenograft A549 lung tumors were sham-treated with PBS or injected with ex vivo TKD/IL-2-activated mouse/human NK cells and mouse/human PD-1 antibody either as a single regimen or in combination. Tumor volume was assessed by MR scanning and tumor-infiltrating CD8 + T, NK, and PD-1 + cells were quantified by immunohistochemistry (IHC). We could show that the adoptive transfer of ex vivo TKD/IL-2-activated mouse NK cells or the inhibition of PD-1 resulted in tumor growth delay and an improved overall survival (OS) in a syngeneic glioblastoma mouse model. A combination of both therapies was well-tolerated and significantly more effective with respect to both outcome parameters than either of the single regimens. A combined treatment in a xenograft lung cancer model showed identical effects in immunodeficient mice bearing human lung cancer after adoptive transfer of TKD/IL-2-activated human effector cells and a human PD-1 antibody. Tumor control was associated with a massive infiltration with CD8 + T and NK cells in both tumor models and a decreased in PD-1 expression on immune effector cells. In summary, a combined approach consisting of activated NK cells and anti-PD-1 therapy is safe and results in a long-term tumor control which is accompanied by a massive tumor immune cell infiltration in 2 preclinical tumor models.

Background: Glioblastoma is the most devastating primary brain tumor of the central nervous system in adults. Magnetic nanocarriers may help not only for a targeted delivery of chemotherapeutic agents into the tumor site but also provide contrast enhancing properties for diagnostics using magnetic resonance imaging (MRI)., Methods: Synthesized hybrid chitosan-dextran superparamagnetic nanoparticles (CS-DX-SPIONs) were characterized using transmission electron microscopy (TEM) and relaxometry studies. Nonlinear magnetic response measurements were employed for confirming the superparamagnetic state of particles. Following in vitro analysis of nanoparticles cellular uptake tumor targeting was assessed in the model of the orthotopic glioma in rodents., Results: CS-DX-SPIONs nanoparticles showed a uniform diameter of 55 nm under TEM and superparamagentic characteristics as determined by T 1 (spin-lattice relaxation time) and T 2 <0.001). Subsequent histological studies proved the accumulation of the nanoparticles inside glioblastoma cells.T 2 values ( P <0.001). Subsequent histological studies proved the accumulation of the nanoparticles inside glioblastoma cells., Conclusion: Hybrid chitosan-dextran magnetic particles demonstrated high MR contrast enhancing properties for the delineation of the brain tumor. Due to a significant retention of the particles in the tumor an application of the CS-DX-SPIONs could not only improve the tumor imaging but also could allow a targeted delivery of chemotherapeutic agents., Competing Interests: Disclosure The authors report no conflicts of interest in this work.

The major stress-inducible 70 kDa heat shock (stress) protein 70 (Hsp70) is frequently overexpressed in highly aggressive tumor cells and thus might serve as a tumor-specific biomarker of aggressive disease. We have previously shown that, in contrast to normal cells, tumor cells present Hsp70 on their plasma membrane. In order to elucidate the role of intracellular and membrane-bound Hsp70 as a potential tumor biomarker in glioblastoma multiforme, herein, we describe protocols for the staining of cytosolic Hsp70 in tumor formalin fixed paraffin-embedded (FFPE) sections using immunohistochemistry, and for plasma membrane-bound Hsp70 by multi-parametric flow cytometry using the cmHsp70.1 monoclonal antibody (mAb).

A unique feature in several non-CNS-tumors is the overexpression of heat shock protein 70 (Hsp70, HSPA1A) in the cytosol, but also its unusual plasma membrane expression and release. Although in gliomas, cytosolic Hsp70 levels are not associated with histological grading, the role of membrane bound and released Hsp70 is still completely unknown. Membrane bound as well as cytosolic Hsp70 can be detected in viable tumor cells with the monoclonal antibody (mAb) cmHsp70.1. Herein, we analysed membrane bound Hsp70 levels in primary and secondary gliomas of different grades and on isolated glioma subpopulations (endothelial cells, CD133-positive cells, primary cultures) by immunohistochemistry and flow cytometry using cmHsp70.1 mAb. Extracellular Hsp70 was determined by a commercial Hsp70 sandwich ELISA (R&D) in plasma samples of glioblastoma patients and healthy volunteers. We found an overexpression of Hsp70 in primary glioblastomas compared to low-grade, anaplastic, or secondary gliomas as determined by immunohistochemistry. Especially in flow cytometry, a strong plasma membrane Hsp70 expression was only observed in primary but not secondary glioblastomas. Within the heterogeneous tumor mass, CD133-positive tumor-initiating and primary glioblastoma cells showed a high membrane Hsp70 expression density, whereas endothelial cells, isolated from glioblastoma tissues only showed a weak staining pattern. Also in plasma samples, secreted Hsp70 protein was significantly increased in patients harbouring primary glioblastomas compared to those with secondary and low grade glioblastomas. Taken together, we show for the first time that cytosolic, membrane bound and extracellular Hsp70 is uniquely overexpressed in primary glioblastomas.

Nanoparticles (NP) as carriers for anti-cancer drugs have shown great promise. Specific targeting of NP to malignant cells, however, remains an unsolved problem. Conjugation of antibodies specific for tumor membrane antigens to NP represents one approach to improve specificity and to increase therapeutic efficacy. In the present study, for the first time a novel membrane heat shock protein (Hsp70)-specific antibody (cmHsp70.1) was coupled to human serum albumin (HSA) NP, loaded with microRNA (miRNA) plasmids to target the inhibitor of apoptosis protein survivin. The physicochemical properties of monodisperse miRNA-loaded NP showed a diameter of 180 nm to 220 nm, a plasmid incorporation of more than 95% and a surface binding capacity of the antibody of 70-80%. Antibody-conjugated NP displayed an increased cellular uptake in U87MG and LN229 glioblastoma cells compared to isotype control antibody, PEG-coupled controls and peripheral blood lymphocytes (PBL). Survivin expression was significantly reduced in cells treated with the Hsp70-miRNA-NP as compared to non-conjugated NP. Hsp70-miRNA-NP enhanced radiation-induced increase in caspase 3/7 activity and decrease in clonogenic cell survival. In summary, cmHsp70.1 miRNA-NP comprise an enhanced tumor cell uptake and increased therapeutic efficacy of radiation therapy in vitro and provide the basis for the development of antibody-based advanced carrier systems for a tumor cell specific targeting., (© 2013.)