Naphtho[1,2-][1,4]diazepinedione-Based P2X4 Receptor Antagonists from Structure-Activity Relationship Studies toward PET Tracer Development.

The P2X4 receptor is implicated in various pathological conditions, including neuropathic pain and cancer. This study reports the development of 1,4-naphthodiazepinedione-based P2X4 receptor antagonists aimed at both therapeutic applications and potential use as PET tracers for imaging P2X4 receptor expression in cancer. Structure-activity relationship studies aided by docking studies and molecular dynamics simulations led to a series of compounds with potent P2X4 receptor antagonism, promising inhibition of interleukin-1β release in THP-1 cells and suitability for radiolabeling with fluorine-18.

18F-labelled gentiobiose as potential PET-radiotracer for specific bacterial imaging: precursor synthesis, radiolabelling and in vitro evaluation.

Aim: Bacterial infections are a clinical challenge, requiring fast and specific diagnosis to ensure effective treatment. Therefore, this project is dedicated to development of positron emission tomography (PET) radiotracers specifically targeting bacteria. Unlike previously developed bacteria-specific radiotracers, which are successful in detecting Gram-negative bacteria, tracers capable of imaging Gram-positive infections are still lacking.

Combining poly-epitope MoonTags and labeled nanobodies for signal amplification in cell-specific PET imaging in vivo.

Immunorecognition provides an excellent basis for targeted imaging techniques covering a wide range from basic research to diagnostics and from single cells to whole organisms. Fluorescence- or radioisotope-labeled antibodies, antibody fragments or nanobodies enable a direct signal readout upon binding and allow for versatile imaging from microscopy to whole-body imaging. However, as the signal intensity directly correlates with the number of labeled antibodies bound to their epitopes (1:1 binding), sensitivity for low-expressing epitopes can be limiting for visualization.

Imaging of the calcium activated potassium channel 3.1 (K 3.1) in vivo using a senicapoc-derived positron emission tomography tracer.

The calcium-activated potassium channel 3.1 (K 3.1) is overexpressed in many tumor entities and has predictive power concerning disease progression and outcome.

Synthesis and biological evaluation of PET tracers designed for imaging of calcium activated potassium channel 3.1 (K3.1) channels .

Expression of the Ca activated potassium channel 3.1 (K3.1) channel (also known as the Gàrdos channel) is dysregulated in many tumor entities and has predictive power with respect to patient survival.

Voxel-Based Analysis of the Relation of 3'-Deoxy-3'-[F]fluorothymidine ([F]FLT) PET and Diffusion-Weighted (DW) MR Signals in Subcutaneous Tumor Xenografts Does Not Reveal a Direct Spatial Relation of These Two Parameters.

Purpose: Multimodal molecular imaging allows a direct coregistration of different images, facilitating analysis of the spatial relation of various imaging parameters. Here, we further explored the relation of proliferation, as measured by [F]FLT PET, and water diffusion, as an indicator of cellular density and cell death, as measured by diffusion-weighted (DW) MRI, in preclinical tumor models. We expected these parameters to be negatively related, as highly proliferative tissue should have a higher density of cells, hampering free water diffusion.

Extracellular Vesicle Transfer from Endothelial Cells Drives VE-Cadherin Expression in Breast Cancer Cells, Thereby Causing Heterotypic Cell Contacts.

Cadherins mediate cohesive contacts between isotypic cells by homophilic interaction and prevent contact between heterotypic cells. Breast cancer cells neighboring endothelial cells (ECs) atypically express vascular endothelial (VE)-cadherin. To understand this EC-induced VE-cadherin expression in breast cancer cells, MCF7 and MDA-MB-231 cells expressing different endogenous cadherins were co-cultured with ECs and analyzed for VE-cadherin at the transcriptional level and by confocal microscopy, flow cytometry, and immunoblotting.

Applications of Small Animal PET.

Understanding the (molecular) mechanisms underlying tumor progression is fundamental for developing and improving cancer diagnosis and therapy. Positron emission tomography (PET) is a method to non-invasively and longitudinally provide such information. Depending on the radioactive tracer employed, a range of molecular processes can be visualized.

Prophylactic Antiviral Activity of Sulfated Glycomimetic Oligomers and Polymers.

In this work, we investigate the potential of highly sulfated synthetic glycomimetics to act as inhibitors of viral binding/infection. Our results indicate that both long-chain glycopolymers and short-chain glycooligomers are capable of preventing viral infection. Notably, glycopolymers efficiently inhibit Human Papillomavirus (HPV16) infection in vitro and maintain their antiviral activity in vivo, while the glycooligomers exert their inhibitory function post attachment of viruses to cells.

Multimodal Molecular Imaging of the Tumour Microenvironment.

The tumour microenvironment (TME) surrounding tumour cells is a highly dynamic and heterogeneous composition of immune cells, fibroblasts, precursor cells, endothelial cells, signalling molecules and extracellular matrix (ECM) components. Due to the heterogeneity and the constant crosstalk between the TME and the tumour cells, the components of the TME are important prognostic parameters in cancer and determine the response to novel immunotherapies. To improve the characterization of the TME, novel non-invasive imaging paradigms targeting the complexity of the TME are urgently needed.

EZH2 Inhibition in Ewing Sarcoma Upregulates G Expression for Targeting with Gene-Modified T Cells.

Chimeric antigen receptor (CAR) engineering of T cells allows one to specifically target tumor cells via cell surface antigens. A candidate target in Ewing sarcoma is the ganglioside G, but heterogeneic expression limits its value. Here we report that pharmacological inhibition of Enhancer of Zeste Homolog 2 (EZH2) at doses reducing H3K27 trimethylation, but not cell viability, selectively and reversibly induces G surface expression in Ewing sarcoma cells.

Thymidine Metabolism as a Confounding Factor for 3'-Deoxy-3'-F-Fluorothymidine Uptake After Therapy in a Colorectal Cancer Model.

Noninvasive monitoring of tumor therapy response helps in developing personalized treatment strategies. Here, we performed sequential PET and diffusion-weighted MRI to evaluate changes induced by a FOLFOX-like combination chemotherapy in colorectal cancer xenografts, to identify the cellular and molecular determinants of these imaging biomarkers. Tumor-bearing CD1 nude mice, engrafted with FOLFOX-sensitive Colo205 colorectal cancer xenografts, were treated with FOLFOX (5-fluorouracil, leucovorin, and oxaliplatin) weekly.

Correction to: The relationship between endogenous thymidine concentrations and [F]FLT uptake in a range of preclinical tumour models.

Unfortunately, the original version of Figs. 4, 5 and 6b in the article [1] contained errors in the n numbers as indicated on the columns. Please note that column heights and error bars in the original figures and data in the ESM tables are correct and statistical tests are valid.

3'-Deoxy-3'-[F]Fluorothymidine Uptake Is Related to Thymidine Phosphorylase Expression in Various Experimental Tumor Models.

Purpose: We recently reported that high thymidine phosphorylase (TP) expression is accompanied by low tumor thymidine concentration and high 3'-deoxy-3'-[F]fluorothymidine ([F]FLT) uptake in four untreated lung cancer xenografts. Here, we investigated whether this relationship also holds true for a broader range of tumor models.

Procedures: Lysates from n = 15 different tumor models originating from n = 6 institutions were tested for TP and thymidylate synthase (TS) expression using western blots.

Targeting Ewing sarcoma with activated and GD2-specific chimeric antigen receptor-engineered human NK cells induces upregulation of immune-inhibitory HLA-G.

Activated and expanded natural killer (NK) cells have substantial cytotoxicity against many tumor cells, but their efficacy to eliminate solid cancers is limited. Here, we used chimeric antigen receptors (CARs) to enhance the activity of NK cells against Ewing sarcomas (EwS) in a tumor antigen-specific manner. Expression of CARs directed against the ganglioside antigen G in activated NK cells increased their responses to G+ allogeneic EwS cells and overcame resistance of individual cell lines to NK cell lysis.

In vivo bioluminescence imaging of neurogenesis - the role of the blood brain barrier in an experimental model of Parkinson's disease.

Bioluminescence imaging in transgenic mice expressing firefly luciferase in Doublecortin (Dcx) neuroblasts might serve as a powerful tool to study the role of neurogenesis in models of brain injury and neurodegeneration using non-invasive, longitudinal in vivo imaging. Therefore, we aimed to use BLI in B6(Cg)-Tyrc-2J/J Dcx-Luc (Doublecortin-Luciferase, Dcx-Luc) mice to investigate its suitability to assess neurogenesis in a unilateral injection model of Parkinson's disease. We further aimed to assess the blood brain barrier leakage associated with the intranigral 6-OHDA injection to evaluate its impact on substrate delivery and bioluminescence signal intensity.

Combined PET Imaging of the Inflammatory Tumor Microenvironment Identifies Margins of Unique Radiotracer Uptake.

The tumor microenvironment is highly heterogeneous. For gliomas, the tumor-associated inflammatory response is pivotal to support growth and invasion. Factors of glioma growth, inflammation, and invasion, such as the translocator protein (TSPO) and matrix metalloproteinases (MMP), may serve as specific imaging biomarkers of the glioma microenvironment.

Preclinical Applications of 3'-Deoxy-3'-[F]Fluorothymidine in Oncology - A Systematic Review.

The positron emission tomography (PET) tracer 3'-deoxy-3'-[F]fluorothymidine ([F]FLT) has been proposed to measure cell proliferation non-invasively . Hence, it should provide valuable information for response assessment to tumor therapies. To date, [F]FLT uptake has found limited use as a response biomarker in clinical trials in part because a better understanding is needed of the determinants of [F]FLT uptake and therapy-induced changes of its retention in the tumor.

Preclinical Evidence That 3'-Deoxy-3'-[18F]Fluorothymidine PET Can Visualize Recovery of Hematopoiesis after Gemcitabine Chemotherapy.

Molecular imaging with the PET tracer 3'-deoxy-3'-[F]fluorothymidine ([F]FLT) allows assessment of the proliferative state of organs in vivo Although used primarily in the oncology clinic, it can also shed light on the proliferation of other tissues, as demonstrated here for monitoring hematopoietic organs that recover after myelosuppressive chemotherapy. In the NMRI nude mouse model, we observed up to a 4.5-fold increase in [F]FLT uptake in bone marrow and spleen on days 2, 3, and 5 after treatment with gemcitabine, a chemotherapeutic agent that is powerfully myelosuppressive in the model.

Gemcitabine Mechanism of Action Confounds Early Assessment of Treatment Response by 3'-Deoxy-3'-[18F]Fluorothymidine in Preclinical Models of Lung Cancer.

3'-Deoxy-3'-[F]fluorothymidine positron emission tomography ([F]FLT-PET) and diffusion-weighted MRI (DW-MRI) are promising approaches to monitor tumor therapy response. Here, we employed these two imaging modalities to evaluate the response of lung carcinoma xenografts in mice after gemcitabine therapy. Caliper measurements revealed that H1975 xenografts responded to gemcitabine treatment, whereas A549 growth was not affected.

The relationship between endogenous thymidine concentrations and [(18)F]FLT uptake in a range of preclinical tumour models.

Background: Recent studies have shown that 3'-deoxy-3'-[(18)F] fluorothymidine ([(18)F]FLT)) uptake depends on endogenous tumour thymidine concentration. The purpose of this study was to investigate tumour thymidine concentrations and whether they correlated with [(18)F]FLT uptake across a broad spectrum of murine cancer models. A modified liquid chromatography-mass spectrometry (LC-MS/MS) method was used to determine endogenous thymidine concentrations in plasma and tissues of tumour-bearing and non-tumour bearing mice and rats.

PEGylated human serum albumin (HSA) nanoparticles: preparation, characterization and quantification of the PEGylation extent.

Modification with poly(ethylene glycol) (PEG) is a widely used method for the prolongation of plasma half-life of colloidal carrier systems such as nanoparticles prepared from human serum albumin (HSA). However, the quantification of the PEGylation extent is still challenging. Moreover, the influence of different PEG derivatives, which are commonly used for nanoparticle conjugation, has not been investigated so far.

Epigenetic dysregulation of KCa 3.1 channels induces poor prognosis in lung cancer.

Epigenomic changes are an important feature of malignant tumors. How tumor aggressiveness is affected by DNA methylation of specific loci is largely unexplored. In genome-wide DNA methylation analyses, we identified the KCa 3.