The BMS-LM ontology for biomedical data reporting throughout the lifecycle of a research study: From data model to ontology.

Biomedical research data reuse and sharing is essential for fostering research progress. To this aim, data producers need to master data management and reporting through standard and rich metadata, as encouraged by open data initiatives such as the FAIR (Findable, Accessible, Interoperable, Reusable) guidelines. This helps data re-users to understand and reuse the shared data with confidence. Therefore, dedicated frameworks are required. The provenance reporting throughout a biomedical study lifecycle has been proposed as a way to increase confidence in data while reusing it. The Biomedical Study - Lifecycle Management (BMS-LM) data model has implemented provenance and lifecycle traceability for several multimodal-imaging techniques but this is not enough for data understanding while reusing it. Actually, in the large scope of biomedical research, a multitude of metadata sources, also called Knowledge Organization Systems (KOSs), are available for data annotation. In addition, data producers uses local terminologies or KOSs, containing vernacular terms for data reporting. The result is a set of heterogeneous KOSs (local and published) with different formats and levels of granularity. To manage the inherent heterogeneity, semantic interoperability is encouraged by the Research Data Management (RDM) community. Ontologies, and more specifically top ontologies such as BFO and DOLCE, make explicit the metadata semantics and enhance semantic interoperability. Based on the BMS-LM data model and the BFO top ontology, the BioMedical Study - Lifecycle Management (BMS-LM) core ontology is proposed together with an associated framework for semantic interoperability between heterogeneous KOSs. It is made of four ontological levels: top/core/domain/local and aims to build bridges between local and published KOSs. In this paper, the conversion of the BMS-LM data model to a core ontology is detailed. The implementation of its semantic interoperability in a specific domain context is explained and illustrated with examples from small animal preclinical research.

Sponges and Their Symbionts as a Source of Valuable Compounds in Cosmeceutical Field.

In the last decades, the marine environment was discovered as a huge reservoir of novel bioactive compounds, useful for medicinal treatments improving human health and well-being. Among several marine organisms exhibiting biotechnological potential, sponges were highlighted as one of the most interesting phyla according to a wide literature describing new molecules every year. Not surprisingly, the first marine drugs approved for medical purposes were isolated from a marine sponge and are now used as anti-cancer and anti-viral agents. In most cases, experimental evidence reported that very often associated and/or symbiotic communities produced these bioactive compounds for a mutual benefit. Nowadays, beauty treatments are formulated taking advantage of the beneficial properties exerted by marine novel compounds. In fact, several biological activities suitable for cosmetic treatments were recorded, such as anti-oxidant, anti-aging, skin whitening, and emulsifying activities, among others. Here, we collected and discussed several scientific contributions reporting the cosmeceutical potential of marine sponge symbionts, which were exclusively represented by fungi and bacteria. Bioactive compounds specifically indicated as products of the sponge metabolism were also included. However, the origin of sponge metabolites is dubious, and the role of the associated biota cannot be excluded, considering that the isolation of symbionts represents a hard challenge due to their uncultivable features.

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.The characterization of the TME by molecular imaging will (1) support early diagnosis and disease follow-up, (2) guide (stereotactic) biopsy sampling, (3) highlight the dynamic changes during disease pathogenesis in a non-invasive manner, (4) help monitor existing therapies, (5) support the development of novel TME-targeting therapies and (6) aid stratification of patients, according to the cellular composition of their tumours in correlation to their therapy response.This chapter will summarize the most recent developments and applications of molecular imaging paradigms beyond FDG for the characterization of the dynamic molecular and cellular changes in the TME.

Multimodal Imaging of Patients With Gliomas Confirms 11C-MET PET as a Complementary Marker to MRI for Noninvasive Tumor Grading and Intraindividual Follow-Up After Therapy.

The value of combined L-( methyl-[11C]) methionine positron-emitting tomography (MET-PET) and magnetic resonance imaging (MRI) with regard to tumor extent, entity prediction, and therapy effects in clinical routine in patients with suspicion of a brain tumor was investigated. In n = 65 patients with histologically verified brain lesions n = 70 MET-PET and MRI (T1-weighted gadolinium-enhanced [T1w-Gd] and fluid-attenuated inversion recovery or T2-weighted [FLAIR/T2w]) examinations were performed. The computer software "visualization and analysis framework volume rendering engine (Voreen)" was used for analysis of extent and intersection of tumor compartments. Binary logistic regression models were developed to differentiate between World Health Organization (WHO) tumor types/grades. Tumor sizes as defined by thresholding based on tumor-to-background ratios were significantly different as determined by MET-PET (21.6 ± 36.8 cm3), T1w-Gd-MRI (3.9 ± 7.8 cm3), and FLAIR/T2-MRI (64.8 ± 60.4 cm3; P < .001). The MET-PET visualized tumor activity where MRI parameters were negative: PET positive tumor volume without Gd enhancement was 19.8 ± 35.0 cm3 and without changes in FLAIR/T2 10.3 ± 25.7 cm3. FLAIR/T2-MRI visualized greatest tumor extent with differences to MET-PET being greater in posttherapy (64.6 ± 62.7 cm3) than in newly diagnosed patients (20.5 ± 52.6 cm3). The binary logistic regression model differentiated between WHO tumor types (fibrillary astrocytoma II n = 10 from other gliomas n = 16) with an accuracy of 80.8% in patients at primary diagnosis. Combined PET and MRI improve the evaluation of tumor activity, extent, type/grade prediction, and therapy-induced changes in patients with glioma and serve information highly relevant for diagnosis and management.

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. Two weeks after lesion, we observed an increase in bioluminescence signal in the ipsilateral hippocampal region in both, 6-OHDA and vehicle injected Dcx-Luc mice. At the same time, no corresponding increase in Dcx+ neuroblast numbers could be observed in the dentate gyrus of C57Bl6 mice. Blood brain barrier leakage was observed in the hippocampal region and in the degenerating substantia nigra of C57Bl6 mice in vivo using T1 weighted Magnetic Resonance Imaging with Gadovist® and ex vivo using Evans Blue Fluorescence Reflectance Imaging and mouse Immunoglobulin G staining. Our data suggests a BLI signal dependency on blood brain barrier permeability, underlining a major pitfall of substrate/tracer dependent imaging in invasive disease models.

6-hydroxydopamine-induced Parkinson's disease-like degeneration generates acute microgliosis and astrogliosis in the nigrostriatal system but no bioluminescence imaging-detectable alteration in adult neurogenesis.

Parkinson's disease is a slowly progressing neurodegenerative disorder caused by loss of dopaminergic neurons in the substantia nigra (SN), leading to severe impairment in motor and non-motor functions. Endogenous subventricular zone (SVZ) neural stem cells constantly give birth to new cells that might serve as a possible source for regeneration in the adult brain. However, neurodegeneration is accompanied by neuroinflammation and dopamine depletion, potentially compromising regeneration. We therefore employed in vivo imaging methods to study striatal deafferentation (N-ω-fluoropropyl-2ß-carbomethoxy-3ß-(4-[(123) I]iodophenyl)nortropane single photon emission computed tomography, DaTscan(™) ) and neuroinflammation in the SN and striatum (N,N-diethyl-2-(2-(4-(2-[(18) F]fluoroethoxy)phenyl)-5,7-dimethylpyrazolo[1,5-a]pyrimidin-3-yl)acetamide positron emission tomography, [(18) F]DPA-714 PET) in the intranigral 6-hydroxydopamine Parkinson's disease mouse model. Additionally, we transduced cells in the SVZ with a lentivirus encoding firefly luciferase and followed migration of progenitor cells in the SVZ-olfactory bulb axis via bioluminescence imaging under disease and control conditions. We found that activation of microglia in the SN is an acute process accompanying the degeneration of dopaminergic cell bodies in the SN. Dopaminergic deafferentation of the striatum does not influence the generation of doublecortin-positive neuroblasts in the SVZ, but generates chronic astrogliosis in the nigrostriatal system.

Mechanistic interrogation of combination bevacizumab/dual PI3K/mTOR inhibitor response in glioblastoma implementing novel MR and PET imaging biomarkers.

PURPOSE: Resistance to bevacizumab (BEV) in glioblastoma is believed to occur via activation of molecular networks including the mTOR/PI3K pathway. Using an MR/PET molecular imaging biomarker approach, we investigated the response to combining BEV with the mTOR/PI3K inhibitor BEZ235. METHODS: Tumours were established by orthotopically implanting U87MG-luc2 cells in mice. Animals were treated with BEZ235 and/or BEV, and imaged using diffusion-weighted-MRI, T2-weighted and T2*-weighted before and after administration of superparamagnetic iron oxide contrast agent. Maps for changes in relaxation rates (ΔR2, ΔR2* and apparent diffusion coefficient) were calculated. Vessel size index and microvessel density index were derived. 3'-Deoxy-3'-[(18)F]fluorothymidine ([(18)F]FLT) PET and O-(2-[(18)F]fluoroethyl)-L-tyrosine ([(18)F]FET) PET were further performed and tumour endothelium/proliferation markers assessed by immunohistochemistry. RESULTS: Treatment with BEV resulted in a pronounced decrease in tumour volume (T2-weighted MRI). No additive effect on tumour volume was observed with the BEV/BEZ235 combination compared with BEV monotherapy. The Ki67 proliferation index and [(18)F]FLT uptake studies were used to support the observations. Using ΔR2* and ΔR2 values, respectively, the BEV/BEZ235 combination significantly reduced tumour microvessel volume in comparison to BEV alone. Decreased microvessel density index was further observed in animals treated with the combination, supported by von Willebrand factor (vWF) immunohistochemistry. [(18)F]FET uptake was decreased following treatment with BEV alone, but was not further reduced following treatment with the combination. vWF immunohistochemistry analysis showed that the mean tumour vessel size was increased in all cohorts. CONCLUSION: Assessing MR imaging biomarker parameters together with [(18)F]FET and [(18)F]FLT PET provided information on mechanism of action of the drug combination and clues as to potential clinical responses. Following translation to clinical use, treatment with a BEV/BEZ235 combination could reduce peritumoral oedema obviating the requirement for steroids. The use of hypothesis-driven molecular imaging studies facilitates the preclinical evaluation of drug response. Studies of this kind may more accurately predict the clinical potential of the BEV/BEZ235 combination regimen as a novel therapeutic approach in oncology.

A systemic transcriptome analysis reveals the regulation of neural stem cell maintenance by an E2F1-miRNA feedback loop.

Stem cell fate decisions are controlled by a molecular network in which transcription factors and miRNAs are of key importance. To systemically investigate their impact on neural stem cell (NSC) maintenance and neuronal commitment, we performed a high-throughput mRNA and miRNA profiling and isolated functional interaction networks of involved mechanisms. Thereby, we identified an E2F1-miRNA feedback loop as important regulator of NSC fate decisions. Although E2F1 supports NSC proliferation and represses transcription of miRNAs from the miR-17∼92 and miR-106a∼363 clusters, these miRNAs are transiently up-regulated at early stages of neuronal differentiation. In these early committed cells, increased miRNAs expression levels directly repress E2F1 mRNA levels and inhibit cellular proliferation. In mice, we demonstrated that these miRNAs are expressed in the neurogenic areas and that E2F1 inhibition represses NSC proliferation. The here presented data suggest a novel interaction mechanism between E2F1 and miR-17∼92 / miR-106a∼363 miRNAs in controlling NSC proliferation and neuronal differentiation.

Optimizing glioblastoma temozolomide chemotherapy employing lentiviral-based anti-MGMT shRNA technology.

Despite treatments combining surgery, radiation-, and chemotherapy, patients affected by glioblastoma (GBM) have a limited prognosis. Addition of temozolomide (TMZ) to radiation therapy is the standard therapy in clinical application, but effectiveness of TMZ is limited by the tumor's overexpression of the DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT). The goal of this study was to use the highly specific and efficient RNA interference (RNAi) pathway to modulate MGMT expression to increase TMZ efficiency in chemotherapy resistant GBM. Using lentiviral-based anti-MGMT small hairpin RNA (shRNA) technology we observed a specific inhibition of the MGMT expression in GBM cell lines as well as in subcutaneous tumors. Tumor growth inhibition was observed following TMZ treatment of xenografts with low MGMT expression in contrast to xenografts with high MGMT expression. Bioluminescence imaging (BLI) measurements indicated that luciferase and shRNA-expressing lentiviruses were able to efficiently transduce the GBM xenografts in vivo. Treatment combining injection of a lentivirus expressing an anti-MGMT shRNA and TMZ induced a reduction of the size of the tumors, in contrast with treatment combining the lentivirus expressing the control shRNA and TMZ. Our data suggest that anti-MGMT shRNA therapy could be used in combination with TMZ chemotherapy in order to improve the treatment of resistant GBM.

Effect of biodegradable polymers upon grazing activity of the sea urchin Paracentrotus lividus (Lmk) revealed by morphological, histological and molecular analyses.

In the last years biodegradable polymers (BPs) were largely used as real opportunity to solve plastic pollution. Otherwise, their wide use in commercial products, such as packaging sector, is causing a new pollution alarm, mainly because few data reported about their behaviour in the environment and toxicity on marine organisms. Our previous results showed that embryos of the sea urchin Paracentrotus lividus (Lmk) exposed to poly(ε-caprolactone) (PCL), poly(3-hydroxybutyrate) (PHB) and poly(lactic acid) (PLA) showed delay of their development and morphological malformations, also affecting at the molecular levels the expression of several genes involved in different functional responses. In the present work for the first time, we tested the effects of five microplastics (MPs) obtained from BPs such as PBS, poly(butylene succinate), PBSA, poly(butylene succinate-co-butylene adipate), PCL, PHB and PLA, upon grazing activity of the sea urchin revealed by: i. histological analysis seeing at the gonadic tissues; ii. morphological analysis of the deriving embryos; iii. molecular analyses on these embryos to detect variations of the gene expression of eighty-seven genes involved in stress response, detoxification, skeletogenesis, differentiation and development. All these results will help in understanding how MP accumulated inside various organs in the adult sea urchins, and more in general in marine invertebrates, could represent risks for the marine environment.

The majority of newly generated cells in the adult mouse substantia nigra express low levels of Doublecortin, but their proliferation is unaffected by 6-OHDA-induced nigral lesion or Minocycline-mediated inhibition of neuroinflammation.

Parkinson's disease is characterized by a selective loss of dopaminergic neurons in the substantia nigra (SN). However, whether regenerative endogenous neurogenesis is taking place in the mammalian SN of parkinsonian and non-parkinsonian brains remains of debate. Here, we tested whether proliferating cells in the SN and their neurogenic potential would be affected by anti-inflammatory treatment under physiological conditions and in the 6-hydroxy-dopamine (6-OHDA) Parkinson's disease mouse model. We report that the majority of newly generated nigral cells are positive for Doublecortin (Dcx), which is an often used marker for neural progenitor cells. Yet, Dcx expression levels in these cells were much lower than in neural progenitor cells of the subventricular zone and the dentate gyrus neural progenitor cells. Furthermore, these newly generated nigral cells are negative for neuronal lineage markers such as TuJ1 and NeuN. Therefore, their neuronal commitment is questionable. Instead, we found evidence for oligodendrogenesis and astrogliosis in the SN. Finally, neither short-term nor long-term inhibition of neuroinflammation by Minocycline- or 6-OHDA-induced lesion affected the numbers of newly generated cells in our disease paradigm. Our findings of adult generated Dcx(+) cells in the SN add important data for understanding the cellular composition and consequently the regenerative capacity of the SN.

Non-invasive imaging of glioma vessel size and densities in correlation with tumour cell proliferation by small animal PET and MRI.

PURPOSE: Angiogenesis is a key event in the progression of glioblastomas (GBM). Our goal was to measure different anatomical and physiological parameters of GBM vessels using steady-state contrast-enhanced magnetic resonance imaging (SSCE-MRI), together with the assessment of biochemical parameters on GBM proliferation and angiogenesis using [(11)C]methyl-L-methionine (MET) and 3'-deoxy-3'-[(18)F]fluorothymidine (FLT) and positron emission tomography (PET). We focused on how these anatomical and biochemical read-outs correlate with one another and with immunohistochemistry. METHODS: SSCE-MRI together with (11)C-MET and (18)F-FLT PET were performed 3 weeks after intracranial implantation of human GBM spheroids in nude rats (n = 8). Total cerebral blood volume (tCBV), blood volume present in microvessels (µCBV), vessel density and size were calculated. Rats were treated with bevacizumab (n = 4) or vehicle (n = 4) for 3 weeks. Imaging was repeated at week 6, and thereafter immunohistochemistry was performed. RESULTS: Three weeks after implantation, MRI showed an increase of vessel density and µCBV in the tumour compared to the contralateral brain. At week 6, non-treated rats showed a pronounced increase of (11)C-MET and (18)F-FLT tumour uptake. Between weeks 3 and 6, tCBV and vessel size increased, whereas vessel density and µCBV decreased. In rats treated with bevacizumab µCBV values were significantly smaller at week 6 than in non-treated rats, whereas the mean vessel size was higher. Accumulation of both radiotracers was lower for the treated versus the non-treated group. Most importantly, non-invasive measurement of tumour vessel characteristics and tumour proliferation correlated to immunohistochemistry findings. CONCLUSION: Our study demonstrates that SSCE-MRI enables non-invasive assessment of the anatomy and physiology of the vasculature of experimental gliomas. Combined SSCE-MRI and (11)C-MET/(18)F-FLT PET for monitoring biochemical markers of angiogenesis and proliferation in addition to vessel anatomy could be useful to improve our understanding of therapy response of gliomas.

Biodegradation of Plastics Induced by Marine Organisms: Future Perspectives for Bioremediation Approaches.

Plastic pollution is a distinctive element of the globalized world. In fact, since the 1970s the expansion and use of plastics, particularly in the consumer and commercial sectors, has given this material a permanent place in our lives. The increasing use of plastic products and the wrong management of end-of-life plastic products have contributed to increasing environmental pollution, with negative impacts on our ecosystems and the ecological functions of natural habitats. Nowadays, plastic pollution is pervasive in all environmental compartments. As aquatic environments are the dumping points for poorly managed plastics, biofouling and biodegradation have been proposed as promising approaches for plastic bioremediation. Known for the high stability of plastics in the marine environment, this represents a very important issue to preserve marine biodiversity. In this review, we have summarized the main cases reported in the literature on the degradation of plastics by bacteria, fungi, and microalgae and the degradation mechanisms involved, to highlight the potential of bioremediation approaches to reduce macro and microplastic pollution.

Effects of biodegradable-based microplastics in Paracentrotus lividus Lmk embryos: Morphological and gene expression analysis.

Plastic pollution is a remarkable environmental issue. In fact, plastic is widespread in the lifetime and serious environmental problems are caused by the improper management of plastic end of life, being plastic litter detected in any environment. Efforts are put to implement the development of sustainable and circular materials. In this scenario, biodegradable polymers, BPs, are promising materials if correctly applied and managed at the end of life to minimize environmental problems. However, a lack of data on BPs fate and toxicity on marine organisms, limits their applicability. In this research, the impact of microplastics obtained from BPs, BMPs, were analyzed on Paracentrotus lividus. Microplastics were produced from five biodegradable polyesters at laboratory scale by milling the pristine polymers, under cryogenic conditions. Morphological analysis of P. lividus embryos exposed to polycaprolactone (PCL), polyhydroxy butyrate (PHB) and polylactic acid (PLA) showed their delay and malformations, which at molecular level are due to variation in expression levels of eighty-seven genes involved in various cellular processes, such as skeletogenesis, differentiation and development, stress, and detoxification response. Exposure to poly(butylene succinate) (PBS) and poly(butylene succinate-co-adipate) (PBSA) microplastics showed no detectable effects on P. lividus embryos. These findings contribute with important data on the effect of BPs on the physiology of marine invertebrates.

Machine Learning of Multi-Modal Tumor Imaging Reveals Trajectories of Response to Precision Treatment.

The standard assessment of response to cancer treatments is based on gross tumor characteristics, such as tumor size or glycolysis, which provide very indirect information about the effect of precision treatments on the pharmacological targets of tumors. Several advanced imaging modalities allow for the visualization of targeted tumor hallmarks. Descriptors extracted from these images can help establishing new classifications of precision treatment response. We propose a machine learning (ML) framework to analyze metabolic-anatomical-vascular imaging features from positron emission tomography, ultrafast Doppler, and computed tomography in a mouse model of paraganglioma undergoing anti-angiogenic treatment with sunitinib. Imaging features from the follow-up of sunitinib-treated (n = 8, imaged once-per-week/6-weeks) and sham-treated (n = 8, imaged once-per-week/3-weeks) mice groups were dimensionally reduced and analyzed with hierarchical clustering Analysis (HCA). The classes extracted from HCA were used with 10 ML classifiers to find a generalized tumor stage prediction model, which was validated with an independent dataset of sunitinib-treated mice. HCA provided three stages of treatment response that were validated using the best-performing ML classifier. The Gaussian naive Bayes classifier showed the best performance, with a training accuracy of 98.7 and an average area under curve of 100. Our results show that metabolic-anatomical-vascular markers allow defining treatment response trajectories that reflect the efficacy of an anti-angiogenic drug on the tumor target hallmark.

Acute stress induces long-term metabolic, functional, and structural remodeling of the heart.

Takotsubo cardiomyopathy is a stress-induced cardiovascular disease with symptoms comparable to those of an acute coronary syndrome but without coronary obstruction. Takotsubo was initially considered spontaneously reversible, but epidemiological studies revealed significant long-term morbidity and mortality, the reason for which is unknown. Here, we show in a female rodent model that a single pharmacological challenge creates a stress-induced cardiomyopathy similar to Takotsubo. The acute response involves changes in blood and tissue biomarkers and in cardiac in vivo imaging acquired with ultrasound, magnetic resonance and positron emission tomography. Longitudinal follow up using in vivo imaging, histochemistry, protein and proteomics analyses evidences a continued metabolic reprogramming of the heart towards metabolic malfunction, eventually leading to irreversible damage in cardiac function and structure. The results combat the supposed reversibility of Takotsubo, point to dysregulation of glucose metabolic pathways as a main cause of long-term cardiac disease and support early therapeutic management of Takotsubo.

Hemifacial myohyperplasia is due to somatic muscular PIK3CA gain-of-function mutations and responds to pharmacological inhibition.

Hemifacial myohyperplasia (HFMH) is a rare cause of facial asymmetry exclusively involving facial muscles. The underlying cause and the mechanism of disease progression are unknown. Here, we identified a somatic gain-of-function mutation of PIK3CA in five pediatric patients with HFMH. To understand the physiopathology of muscle hypertrophy in this context, we created a mouse model carrying specifically a PIK3CA mutation in skeletal muscles. PIK3CA gain-of-function mutation led to striated muscle cell hypertrophy, mitochondria dysfunction, and hypoglycemia with low circulating insulin levels. Alpelisib treatment, an approved PIK3CA inhibitor, was able to prevent and reduce muscle hypertrophy in the mouse model with correction of endocrine anomalies. Based on these findings, we treated the five HFMH patients. All patients demonstrated clinical, esthetical, and radiological improvement with proof of target engagement. In conclusion, we show that HFMH is due to somatic alteration of PIK3CA and is accessible to pharmacological intervention.

The translocator protein ligand [¹8F]DPA-714 images glioma and activated microglia in vivo.

PURPOSE: In recent years there has been an increase in the development of radioligands targeting the 18-kDa translocator protein (TSPO). TSPO expression is well documented in activated microglia and serves as a biomarker for imaging neuroinflammation. In addition, TSPO has also been reported to be overexpressed in a number of cancer cell lines and human tumours including glioma. Here we investigated the use of [(18)F]DPA-714, a new TSPO positron emission tomography (PET) radioligand to image glioma in vivo. METHODS: We studied the uptake of [(18)F]DPA-714 in three different rat strains implanted with 9L rat glioma cells: Fischer (F), Wistar (W) and Sprague Dawley (SD) rats. Dynamic [(18)F]DPA-714 PET imaging, kinetic modelling of PET data and in vivo displacement studies using unlabelled DPA-714 and PK11195 were performed. Validation of TSPO expression in 9L glioma cell lines and intracranial 9L gliomas were investigated using Western blotting and immunohistochemistry of brain tissue sections. RESULTS: All rats showed significant [(18)F]DPA-714 PET accumulation at the site of 9L tumour implantation compared to the contralateral brain hemisphere with a difference in uptake among the three strains (F > W > SD). The radiotracer showed high specificity for TSPO as demonstrated by the significant reduction of [(18)F]DPA-714 binding in the tumour after administration of unlabelled DPA-714 or PK11195. TSPO expression was confirmed by Western blotting in 9L cells in vitro and by immunohistochemistry ex vivo. CONCLUSION: The TSPO radioligand [(18)F]DPA-714 can be used for PET imaging of intracranial 9L glioma in different rat strains. This preclinical study demonstrates the feasibility of employing [(18)F]DPA-714 as an alternative radiotracer to image human glioma.

Preclinical evaluation of targeted therapies in Sdhb-mutated tumors.

Therapies for metastatic SDHB-dependent pheochromocytoma and paraganglioma (PPGL) are limited and poorly efficient. New targeted therapies and identification of early non-invasive biomarkers of response are thus urgently needed for these patients. We characterized an in vivo allograft model of spontaneously immortalized murine chromaffin cells (imCC) with inactivation of the Sdhb gene by dynamic contrast-enhanced MRI (DCE-MRI) and 18FDG-PET. We evaluated the response to several therapies: IACS-010759 (mitochondrial respiratory chain complex I inhibitor), sunitinib (tyrosine kinase inhibitor with anti-angiogenic activity), talazoparib (poly ADP ribose polymerase (PARP) inhibitor) combined or not to temozolomide (alkylating agent), pharmacological inhibitors of HIF2a (PT2385 and PT2977 (belzutifan)) and molecular inactivation of HIF2a (imCC Sdhb-/- shHIF2a). Multimodal imaging was performed, including magnetic resonance spectroscopy (1H-MRS) to monitor the level of succinate in vivo. The allografted model of Sdhb-/- imCC reflected SDHB-deficient tumors, with increased angiogenesis and a particular avidity for 18FDG. After 14 days of treatment, IACS-010759, sunitinib and talazoparib at high doses allowed a significant reduction of the tumor volumes. In contrast to the tumor growth inhibition observed in Sdhb-/- shHIF2a imCC tumors, pharmacological inhibitors of HIF2a (PT2385 and belzutifan) showed no antitumor action in this model, alone or in combination with sunitinib. 1H-MRS, but not DCE-MRI, enabled the monitoring response to sunitinib, which was the best treatment in this study, promoting a decrease in succinate levels detected in vivo. This study paves the way for new therapeutic options and reveals a potential new early biomarker of response to treatment in SDHB-dependent PPGL.