The development of a hiPSC-based platform to identify tissue-dependencies of IDH1 R132H.

The application of patient-derived (PD) in vitro tumor models represents the classical strategy for clinical translational oncology research. Using these cellular heterogeneous cultures for the isolation of cancer stem cells (CSCs), suggested to be the main driver for disease malignancy, relies on the use of surrogate biomarkers or is based on CSC-enriching culture conditions. However, the ability of those strategies to exclusively and efficiently enrich for CSC pool has been questioned. Here we present an alternative in vitro CSC model based on the oncogenic transformation of single clone-derived human induced pluripotent stem cells (hiPSC). Hotspot mutations in the DNA encoding for the R132 codon of the enzyme isocitrate dehydrogenase 1 (IDH1) and codon R175 of p53 are commonly occurring molecular features of different tumors and were selected for our transformation strategy. By choosing p53 mutant glial tumors as our model disease, we show that in vitro therapy discovery tests on IDH1-engineered synthetic CSCs (sCSCs) can identify kinases-targeting chemotherapeutics that preferentially target tumor cells expressing corresponding genetic alteration. In contrast, neural stem cells (NSCs) derived from the IDH1R132H overexpressing hiPSCs increase their resistance to the tested interventions indicating glial-to-neural tissue-dependent differences of IDH1R132H. Taken together, we provide proof for the potential of our sCSC technology as a potent addition to biomarker-driven drug development projects or studies on tumor therapy resistance. Moreover, follow-up projects such as comparing in vitro drug sensitivity profiles of hiPSC-derived tissue progenitors of different lineages, might help to understand a variety of tissue-related functions of IDH1 mutations.

Meta-review on Perforation Model of Subarachnoid Hemorrhage in Mice: Filament Material as a Possible Moderator of Mortality.

Robust preclinical models are inevitable for researchers to unravel pathomechanisms of subarachnoidal hemorrhage (SAH). For the mouse perforation model of SAH, the goal of this meta-review was the determination of variances in mortality, SAH severity grade, and vasospasm, and their experimental moderators, as many researchers are facing with incomparable results. We searched on the databases PubMed, Embase, and Web of Science for articles describing in vivo experiments using the SAH perforation mouse model and measuring mortality, SAH grade, and/or vasospasm. After screening, 42 articles (total of 1964 mice) were included into systematic review and meta-analysis. Certain model characteristics were insufficiently reported, e.g., perforation location (not reported in six articles), filament (material (n = 15) and tip texture (n = 25)), mouse age (n = 14), and weight (n = 10). Used injective anesthetics and location of perforation showed large variation. In a random-effects meta-analysis, the overall animal mortality following SAH was 21.3% [95% CI: 17.5%, 25.7%] and increased with longer observational periods. Filament material significantly correlated with animal mortality (p = 0.024) after exclusion of hyperacute studies (time after SAH induction < 24 h). Reported mean SAH grade was 10.7 [9.6, 11.7] on the scale of Sugawara (J Neurosci Methods 167:327-34, 2008). Furthermore, mean diameter of large cerebral arteries after SAH was reduced by 27.6% compared to sham-operated non-SAH mice. Uniforming standards of experimental procedures and their reporting are indispensable to increase overall comparability.

In-Vitro Use of Verteporfin for Photodynamic Therapy in Glioblastoma.

BACKGROUND: Stummer et al. established fluorescence-guided surgery (FGS) for glioblastoma (GBM) using 5-aminolevulinic acid (5-ALA). Its metabolite, protoporphyrin IX (PPIX), is also a photosensitizer and can be used for photodynamic therapy (PDT) using a laser beam of 635 nm. The porphyrin derivate verteporfin (VP) was discovered to have properties to penetrate the brain, pharmacologically target glioma cells, and is approved for PDT of choroidal neovascularization in wet age-related macular degeneration at 689 nm. OBJECTIVE: To elucidate whether GBM cell lines are susceptible to PDT with second-generation photosensitizer VP. METHODS: Human glioma cell lines LN229, HSR-GBM1, and a low-passage patient-derived GBM cell line P1 were treated with variable concentrations of VP for 24 h, followed by PDT at 689 nm using a diode laser light. Cell viability was measured using the MTT assay and VP uptake was measured using a desktop cytometer. RESULTS: Significantly higher cell death following PDT with VP compared to VP treatment alone or no treatment was detected in all cell models (LN229, HSR-GBM1, P1). Flowcytometric measurements revealed a concentration-dependent cellular uptake of VP after 24 h incubation up to 99% at 10 µM (HSR-GBM1). CONCLUSION: This study demonstrates that PDT with VP causes cell death in GBM cells at marginal concentrations. Additionally, red spectrum fluorescence was detected at therapeutic concentrations in all cell lines, validating the cellular uptake of VP in GBM cells. VP, therefore, is not only a potential drug for targeting GBM pharmacologically but can be used as an optical imaging dye in surgery and photosensitizer to make GBM susceptible to PDT.

WNT/ß-Catenin-Mediated Resistance to Glucose Deprivation in Glioblastoma Stem-like Cells.

Isocitrate dehydrogenase (IDH)-wildtype glioblastoma is the most common primary malignant brain tumor. It is associated with a particularly poor prognosis, as reflected by an overall median survival of only 15 months in patients who undergo a supramarginal surgical reduction of the tumor mass followed by combined chemoradiotherapy. The highly malignant nature of IDH-wildtype glioblastoma is thought to be driven by glioblastoma stem-like cells (GSCs) that harbor the ability of self-renewal, survival, and adaptability to challenging environmental conditions. The wingless (WNT) signaling pathway is a phylogenetically highly conserved stemness pathway, which promotes metabolic plasticity and adaptation to a nutrient-limited tumor microenvironment. To unravel the reciprocal regulation of the WNT pathway and the nutrient-limited microenvironment, glioblastoma cancer stem-like cells were cultured in a medium with either standard or reduced glucose concentrations for various time points (24, 48, and 72 h). Glucose depletion reduced cell viability and facilitated the survival of a small population of starvation-resistant tumor cells. The surviving cells demonstrated increased clonogenic and invasive properties as well as enhanced chemosensitivity to pharmacological inhibitors of the WNT pathway (LGK974, berberine). Glucose depletion partially led to the upregulation of WNT target genes such as CTNNB1, ZEB1, and AXIN2 at the mRNA and corresponding protein levels. LGK974 treatment alone or in combination with glucose depletion also altered the metabolite concentration in intracellular compartments, suggesting WNT-mediated metabolic regulation. Taken together, our findings suggest that WNT-mediated metabolic plasticity modulates the survival of GSCs under nutrient-restricted environmental conditions.

CD133-Functionalized Gold Nanoparticles as a Carrier Platform for Telaglenastat (CB-839) against Tumor Stem Cells.

The failure of a long-lasting curative therapeutic benefit of currently applied chemotherapies against malignant cancers is suggested to be caused by the ineffectiveness of such interventions on cancer stem cells (CSCs). CD133/AC133 is a cell surface protein previously shown to have potential to identify CSCs in various tumors, including brain tumors. Moreover, an increase in the rate of cellular metabolism of glutamine and glucose are contributors to the fast cellular proliferation of some high-grade malignancies. Inhibition of glutaminolysis by utilizing pharmacological inhibitors of the enzyme glutaminase 1 (GLS1) can be an effective anti-CSC strategy. In this study, the clinical-stage GLS1 inhibitor Telaglenastat (CB-839) was loaded into PEGylated gold nanoparticles equipped with the covalently conjugated CD133 aptamer (Au-PEG-CD133-CB-839) and exposed to a collection of CD133-positive brain tumor models in vitro. Our results show that Au-PEG-CD133-CB-839 significantly decreased the viability of CD133-postive cancer cells in a dose-dependent manner, which was higher as compared to the effects of treatment of the cells with the individual components of the assembled nanodrug. Interestingly, the treatment effect was observed in glioblastoma stem cells modeling different transcriptomic subtypes of the disease. The presented platform is the fundament for subsequent target specificity characterization and in vivo application.

Progenitor cells derived from gene-engineered human induced pluripotent stem cells as synthetic cancer cell alternatives for in vitro pharmacology.

Limitations in genetic stability and recapitulating accurate physiological disease properties challenge the utility of patient-derived (PD) cancer models for reproducible and translational research. A portfolio of isogenic human induced pluripotent stem cells (hiPSCs) with different pan-cancer relevant oncoprotein signatures followed by differentiation into lineage-committed progenitor cells was genetically engineered. Characterization on molecular and biological level validated successful stable genetic alterations in pluripotency state as well as upon differentiation to prove the functionality of our approach. Meanwhile proposing core molecular networks possibly involved in early dysregulation of stem cell homeostasis, the application of our cell systems in comparative substance testing indicates the potential for cancer research such as identification of augmented therapy resistance of stem cells in response to activation of distinct oncogenic signatures.

Current Technologies for RNA-Directed Liquid Diagnostics.

There is unequivocal acceptance of the variety of enormous potential liquid nucleic acid-based diagnostics seems to offer. However, the existing controversies and the increased awareness of RNA-based techniques in society during the current global COVID-19 pandemic have made the readiness of liquid nucleic acid-based diagnostics for routine use a matter of concern. In this regard-and in the context of oncology-our review presented and discussed the status quo of RNA-based liquid diagnostics. We summarized the technical background of the available assays and benchmarked their applicability against each other. Herein, we compared the technology readiness level in the clinical context, economic aspects, implementation as part of routine point-of-care testing as well as performance power. Since the preventive care market is the most promising application sector, we also investigated whether the developments predominantly occur in the context of early disease detection or surveillance of therapy success. In addition, we provided a careful view on the current biotechnology investment activities in this sector to indicate the most attractive strategies for future economic success. Taken together, our review shall serve as a current reference, at the interplay of technology, clinical use and economic potential, to guide the interested readers in this rapid developing sector of precision medicine.

Testing the Stability of Drug Resistance on Cryopreserved, Gene-Engineered Human Induced Pluripotent Stem Cells.

Human induced pluripotent stem cells (hiPSCs) have emerged as a powerful tool for in vitro modelling of diseases with broad application in drug development or toxicology testing. These assays usually require large quantities of hiPSC, which can entail long-term storage via cryopreservation of the same cell charges. However, it is essential that cryopreservation does not oppose durable changes on the cells. In this project, we characterize one parameter of functionality of one that is well established in the field, in a different research context, an applied hiPSC line (iPS11), namely their resistance to a medium size library of chemo interventions (>160 drugs). We demonstrate that cells, before and after cryopreservation, do not change their relative overall drug response phenotypes, as defined by identification of the top 20 interventions causing dose-dependent reduction of cell growth. Importantly, also frozen cells that are exogenously enforced for stable overexpression of oncogenes myelocytomatosis (cMYC) or tumor protein 53 mutation (TP53R175H), respectively, are not changed in their relative top 20 drugs response compared to their non-frozen counterparts. Taken together, our results support iPSCs as a reliable in vitro platform for in vitro pharmacology, further raising hopes that this technology supports biomarker-associated drug development. Given the general debate on ethical and economic problems associated with the reproducibly crisis in biomedicine, our results may be of interest to a wider audience beyond stem cell research.

Carbonic Anhydrase XII is a Clinically Significant, Molecular Tumor-Subtype Specific Therapeutic Target in Glioma with the Potential to Combat Invasion of Brain Tumor Cells.

BACKGROUND: The metabolic enzyme carbonic anhydrase 12 (CA12/CAXII) emerges as a promising cancer therapeutic target with drug development projects underway. Previous reports proposed the relevance of CA12 in the context of glioma but are limited in patient data quantity, ignore ethnic diversity of patients or rely on semi-quantitative, thereby out of date, methodology. Moreover, little is known on the association of CA12 to brain tumor stemness or on the effect of anti-CAXII-directed monotherapies on glioma stem cells (GSCs), in particular their response regarding mesenchymal differentiation status. METHODS: We performed in silico analysis on three independent, large-scale patient datasets interrogating state of the art molecular diagnostics alongside clinical outcomes. We analyzed CAXII abundance on a collection of GSCs and functionally tested their response to exposure to CAXII blocking antibody 6A10. RESULTS: CA12 is highly expressed in glial tumors compared with normal tissue and predicts for poor clinical course of tumor patients. CA12 expression in glioblastoma significantly correlates with clinically established, molecular markers of IDH1WT DNA, WHO grade IV or absence of 1p/19q chromosome arm co-deletion. Furthermore, tumors with elevated CA12 cluster into the mesenchymal transcription subclass of the disease. CAXII abundance in different GSCs ranges from almost absent to high levels and does not correlate to stem cell marker CD133/AC133 cell surface expression. Moreover, aiming to pharmacologically block CAXII in our cells with antibody 6A10 caused significant functional response only in one of the tested GSCs models, featuring suppression of cell invasion accompanied by reduction of ZEB1 protein and other stem cell markers. CONCLUSION: CA12 represents a clinically relevant and molecular brain tumor-subtype specific therapeutic target. Our correlative data from experimental and clinical samples does not support CA12/CAXII to be GSC specific. 6A10 possesses promising potential to impede the invasive capacity of glioma cells and supports the emerging concept that CAXII interacts with cancer EMT programs. However, further mechanistic studies are required to comprehensively assess the therapeutic potential of 6A10 and to identify different resistance mechanisms of GSCs.

Augmented Therapeutic Potential of Glutaminase Inhibitor CB839 in Glioblastoma Stem Cells Using Gold Nanoparticle Delivery.

Gold nanoparticles (Au NPs) are studied as delivery systems to enhance the effect of the glutaminase1 inhibitor CB839, a promising drug candidate already in clinical trials for tumor treatments. Au NPs were synthesized using a bottom-up approach and covered with polymers able to bind CB839 as a Au-polymer-CB839 conjugate. The drug loading efficiency (DLE) was determined using high-performance liquid chromatography and characterization of the CB839-loaded NPs was done with various microscopic and spectroscopic methods. Despite the chemical inertness of CB839, Au NPs were efficient carriers with a DLE of up to 12%, depending on the polymer used. The therapeutic effect of CB839 with and without Au was assessed in vitro in 2D and 3D glioblastoma (GBM) cell models using different assays based on the colony formation ability of GBM stem cells (GSCs). To avoid readout disturbances from the Au metal, viability methods which do not require optical detection were hereby optimized. These showed that Au NP delivery increased the efficacy of CB839 in GSCs, compared to CB839 alone. Fluorescent microscopy proved successful NP penetration into the GSCs. With this first attempt to combine CB839 with Au nanotechnology, we hope to overcome delivery hurdles of this pharmacotherapy and increase bioavailability in target sites.

Different Calculation Strategies Are Congruent in Determining Chemotherapy Resistance of Brain Tumors In Vitro.

In cancer pharmacology, a drug candidate's therapeutic potential is typically expressed as its ability to suppress cell growth. Different methods in assessing the cell phenotype and calculating the drug effect have been established. However, inconsistencies in drug response outcomes have been reported, and it is still unclear whether and to what extent the choice of data post-processing methods is responsible for that. Studies that systematically examine these questions are rare. Here, we compare three established calculation methods on a collection of nine in vitro models of glioblastoma, exposed to a library of 231 clinical drugs. The therapeutic potential of the drugs is determined on the growth curves, using growth inhibition 50% (GI50) and point-of-departure (PoD) as the criteria. An effect is detected on 36% of the drugs when relying on GI50 and on 27% when using PoD. For the area under the curve (AUC), a threshold of 9.5 or 10 could be set to discriminate between the drugs with and without an effect. GI50, PoD, and AUC are highly correlated. The ranking of substances by different criteria varies somewhat, but the group of the top 20 substances according to one criterion typically includes 17-19 top candidates according to another. In addition to generating preclinical values with high clinical potential, we present off-target appreciation of top substance predictions by interrogating the drug response data of non-cancer cells in our calculation technology.

Rapalink-1 Targets Glioblastoma Stem Cells and Acts Synergistically with Tumor Treating Fields to Reduce Resistance against Temozolomide.

Glioblastoma (GBM) is a lethal disease with limited clinical treatment options available. Recently, a new inhibitor targeting the prominent cancer signaling pathway mTOR was discovered (Rapalink-1), but its therapeutic potential on stem cell populations of GBM is unknown. We applied a collection of physiological relevant organoid-like stem cell models of GBM and studied the effect of RL1 exposure on various cellular features as well as on the expression of mTOR signaling targets and stem cell molecules. We also undertook combination treatments with this agent and clinical GBM treatments tumor treating fields (TTFields) and the standard-of-care drug temozolomide, TMZ. Low nanomolar (nM) RL1 treatment significantly reduced cell growth, proliferation, migration, and clonogenic potential of our stem cell models. It acted synergistically to reduce cell growth when applied in combination with TMZ and TTFields. We performed an in silico analysis from the molecular data of diverse patient samples to probe for a relationship between the expression of mTOR genes, and mesenchymal markers in different GBM cohorts. We supported the in silico results with correlative protein data retrieved from tumor specimens. Our study further validates mTOR signaling as a druggable target in GBM and supports RL1, representing a promising therapeutic target in brain oncology.

A computational guided, functional validation of a novel therapeutic antibody proposes Notch signaling as a clinical relevant and druggable target in glioma.

The Notch signaling network determines stemness in various tissues and targeting signaling activity in malignant brain cancers by gamma-secretase inhibitors (GSI) has shown promising preclinical success. However, the clinical translation remains challenging due to severe toxicity side effects and emergence of therapy resistance. Better anti-Notch directed therapies, specifically directed against the tumor promoting Notch receptor 1 signaling framework, and biomarkers predicting response to such therapy are of highest clinical need. We assessed multiple patient datasets to probe the clinical relevance Notch1 activation and possible differential distribution amongst molecular subtypes in brain cancers. We functionally assessed the biological effects of the first-in-human tested blocking antibody against Notch1 receptor (brontictuzumab, BRON) in a collection of glioma stem-like cell (GSC) models and compared its effects to genetic Notch1 inhibition as well as classical pharmacological Notch inhibitor treatment using gamma-secretase inhibitor MRK003. We also assess effects on Wingless (WNT) stem cell signaling activation, which includes the interrogation of genetic WNT inhibition models. Our computed transcriptional Notch pathway activation score is upregulated in neural stem cells, as compared to astrocytes; as well as in GSCs, as compared to differentiated glioblastoma cells. Moreover, the Notch signature is clinical predictive in our glioblastoma patient discovery and validation cohort. Notch signature is significantly increased in tumors with mutant IDH1 genome and tumors without 1p and 19q co-deletion. In GSCs with elevated Notch1 expression, BRON treatment blocks transcription of Notch pathway target genes Hes1/Hey1, significantly reduced the amount of cleaved Notch1 receptor protein and caused significantly impairment of cellular invasion. Benchmarking this phenotype to those observed with genetic Notch1 inhibition in corresponding cell models did result in higher reduction of cell invasion under chemotherapy. BRON treatment caused signs of upregulation of Wingless (WNT) stem cell signaling activity, and vice versa, blockage of WNT signaling caused induction of Notch target gene expression in our models. We extend the list of evidences that elevated Notch signal expression is a biomarker signature declaring stem cell prevalence and useful for predicting negative clinical course in glioblastoma. By using functional assays, we validated a first in man tested Notch1 receptor specific antibody as a promising drug candidate in the context of neuro oncology and propose biomarker panel to predict resistance and therapy success of this treatment option. We note that the observed phenotype seems only in part due to Notch1 blockage and the drug candidate leads to activation of off target signals. Further studies addressing a possible emergence of therapy resistance due to WNT activation need to be conducted. We further validated our 3D disease modeling technology to be of benefit for drug development projects.

DNA promoter methylation of CCM genes in human cerebral cavernous malformations: Importance of confirming MSP data through sequencing.

BACKGROUND: Cerebral cavernous malformations (CCMs) is the second most common cerebrovascular disease and is classified as familial (20%) and sporadic (80%) forms. Loss of function mutation of three CCM genes results in the familial CCM. Considering the similar clinic presentation of familial and sporadic CCMs, and based on enriched CpG islands in the DNA promoter region of three CCM genes, we hypothesized that DNA methylation of the CpG islands of the CCM genes is involved in human CCM, thereby leading to loss of CCM genes. MATERIAL AND METHODS: 69 human CCMs including sporadic (n = 40), multiple (n = 15) and familial (n = 14) cases. DNA was extracted from the surgical specimens of CCMs followed by bisulfite conversion. The methylation status of the promoter regions of three CCM genes was detected by methylation specific PCR (MSP). To confirm the results of MSP, four MSP-positive probes showing CCM3 methylation underwent deep bisulfite sequencing (DBS). RESULTS: MSP mostly excluded methylation of CCM1 and CCM2 promotor regions (data not shown). In the case of CCM3, 12 out of 55 sporadic cases showed positivity for MSP (21.8%). Deep bisulfite sequencing revealed that four CCM3 MSP positive cases were all negative for DNA methylation. CONCLUSION: The present study suggests that DNA promotor methylation of CCM1-3 genes is not involved in human family CCMs and that it is important to confirm MSP data with DBS. Further study with higher number of sporadic CCM patients is required for better understanding whether this epigenetic mechanism is involved in the pathology of CCM.

An inexpensive and easy-to-implement approach to a Quality Management System for an academic research lab.

Background: Increasing concerns emerge regarding the limited success in reproducing data and translating research results into applications. This is a major problem for science, society and economy. Driven by industry or scientific networks, several attempts to combat this crisis are initiated. However, only few measures address the applicability and feasibility of implementation of actions into an academic research environment with limited resources. Methods: Here we propose a strategy catalogue aiming for a quality management system suitable for many research labs, on the example of a cell culture focused laboratory. Our proposal is guided by its inexpensiveness and possibility of rapid installation.  For this we used eLabFTW, an electronic lab book, as hub for all other components of our Quality Management System (QMS) and digital storage of lab journals. We introduced Standard Operation Procedures (SOPs) as well as a managed bio bank for safer long-term storage of bio samples. Next, we set up a lab meeting as feedback mechanism for the QMS. Finally, we implemented an automated pipeline to be used for example for drug screens. Results: With this effort we want to reduce individual differences in work techniques, to further improve the quality of our results. Although, just recently established, we can already observe positive outcomes in quality of experimental results, improvements in sample and data storage, stakeholder engagement and even promotion of new scientific discoveries. Conclusions: We believe that our experiences can help to establish a road map to increase value and output of preclinical research in academic labs with limited budget and personnel.

Robot technology identifies a Parkinsonian therapeutics repurpose to target stem cells of glioblastoma.

Aim: Glioblastoma is a heterogeneous lethal disease, regulated by a stem-cell hierarchy and the neurotransmitter microenvironment. The identification of chemotherapies targeting individual cancer stem cells is a clinical need. Methodology: A robotic workstation was programmed to perform a drug concentration to cell-growth analysis on an in vitro model of glioblastoma stem cells (GSCs). Mode-of-action analysis of the selected top substance was performed with manual repetition assays and acquisition of further parameters. Results: We identified 22 therapeutic potential substances. Three suggested a repurpose potential of neurotransmitter signal-modulating agents to target GSCs, out of which the Parkinson's therapeutic trihexyphenidyl was most effective. Manual repetition assays and initial mode of action characterization revealed suppression of cell proliferation, cell cycle and survival. Conclusion: Anti-neurotransmitter signaling directed therapy has potential to target GSCs. We established a drug testing facility that is able to define a mid-scale chemo responsome of in vitro cancer models, possibly also suitable for other cell systems.

A comparative pharmaco-metabolomic study of glutaminase inhibitors in glioma stem-like cells confirms biological effectiveness but reveals differences in target-specificity.

Cancer cells upregulate anabolic processes to maintain high rates of cellular turnover. Limiting the supply of macromolecular precursors by targeting enzymes involved in biosynthesis is a promising strategy in cancer therapy. Several tumors excessively metabolize glutamine to generate precursors for nonessential amino acids, nucleotides, and lipids, in a process called glutaminolysis. Here we show that pharmacological inhibition of glutaminase (GLS) eradicates glioblastoma stem-like cells (GSCs), a small cell subpopulation in glioblastoma (GBM) responsible for therapy resistance and tumor recurrence. Treatment with small molecule inhibitors compound 968 and CB839 effectively diminished cell growth and in vitro clonogenicity of GSC neurosphere cultures. However, our pharmaco-metabolic studies revealed that only CB839 inhibited GLS enzymatic activity thereby limiting the influx of glutamine derivates into the TCA cycle. Nevertheless, the effects of both inhibitors were highly GLS specific, since treatment sensitivity markedly correlated with GLS protein expression. Strikingly, we found GLS overexpressed in in vitro GSC models as compared with neural stem cells (NSC). Moreover, our study demonstrates the usefulness of in vitro pharmaco-metabolomics to score target specificity of compounds thereby refining drug development and risk assessment.

Influence of synthesis methods on the internalization of fluorescent gold nanoparticles into glioblastoma stem-like cells.

Glioblastoma (GBM) is an aggressive disease with currently no satisfying treatment option available. GBM cells with stem cell properties are thought to be responsible for the initiation and propagation of the disease, as well as main contributors to the emergence of therapy resistance. In this work, we developed a novel method to synthesize fluorescent gold nanoparticles as potential drug and gene delivery systems for GBM therapy, able to penetrate three-dimensional stem cell selected patient-derived GBM neurosphere systems in vitro. By using polyethylene imine (PEI) as a stabilizer and reducing agent, as well as fluorescein isothiocyanate (FITC) as a fluorescent marker, our fully in-house developed fluorescent gold nanoparticles (AuPEI-FITC NPs) with core sizes between 3 and 6 nm were obtained via a fast microwave-assisted reaction. Cytotoxicity, adsorption and internalization of AuPEI-FITC NPs into the cell lines JHH520, 407 and GBM1 were investigated using the cellular growth assay and fluorescence-activated cell sorting (FACS) analysis. AuPEI-FITC NPs showed no apparent cytotoxicity and an uptake in cells of up to ~80%. A differentiation between surface-bound and internalized AuPEI-FITC NPs was possible by quenching extracellular signals. This resulted in a maximal internalization degree of 61%, which depends highly on the synthesis method of the nanoparticles and the cell type tested. The best internalization was found for AuPEI-FITC1 which was prepared in a one pot reaction from KAuCl4, PEI and FITC. Thus, appropriately synthesized AuPEI-FITC NPs show great potential as vehicles to transport DNA or drugs in GBM cells.

Loss of programmed cell death 10 activates tumor cells and leads to temozolomide-resistance in glioblastoma.

PURPOSE: Glioblastoma (GBM) is one of the most aggressive and incurable primary brain tumors. Identification of novel therapeutic targets is an urgent priority. Programmed cell death 10 (PDCD10), a ubiquitously expressed apoptotic protein, has shown a dual function in different types of cancers and in chemo-resistance. Recently, we reported that PDCD10 was downregulated in human GBM. The aim of this study was to explore the function of PDCD10 in GBM cells. METHODS: PDCD10 was knocked down in three GBM cell lines (U87, T98g and LN229) by lentiviral-mediated shRNA transduction. U87 and T98g transduced cells were used for phenotype study and LN229 and T98g cells were used for apoptosis study. The role of PDCD10 in apoptosis and chemo-resistance was investigated after treatment with staurosporine and temozolomide. A GBM xenograft mouse model was used to confirm the function of PDCD10 in vivo. A protein array was performed in PDCD10-knockdown and control GBM cells. RESULTS: Knockdown of PDCD10 in GBM cells promoted cell proliferation, adhesion, migration, invasion, and inhibited apoptosis and caspase-3 activation. PDCD10-knockdown accelerated tumor growth and increased tumor mass by 2.1-fold and led to a chemo-resistance of mice treated with temozolomide. Immunostaining revealed extensive Ki67-positive cells and less activation of caspase-3 in PDCD10-knockdown tumors. The protein array demonstrated an increased release of multiple growth factors from PDCD10-knockdown GBM cells. CONCLUSIONS: Loss of programmed cell death 10 activates tumor cells and leads to temozolomide-resistance in GBM, suggesting PDCD10 as a potential target for GBM therapy.

Prognostic impact of vitamin B6 metabolism in lung cancer.

Patients with non-small cell lung cancer (NSCLC) are routinely treated with cytotoxic agents such as cisplatin. Through a genome-wide siRNA-based screen, we identified vitamin B6 metabolism as a central regulator of cisplatin responses in vitro and in vivo. By aggravating a bioenergetic catastrophe that involves the depletion of intracellular glutathione, vitamin B6 exacerbates cisplatin-mediated DNA damage, thus sensitizing a large panel of cancer cell lines to apoptosis. Moreover, vitamin B6 sensitizes cancer cells to apoptosis induction by distinct types of physical and chemical stress, including multiple chemotherapeutics. This effect requires pyridoxal kinase (PDXK), the enzyme that generates the bioactive form of vitamin B6. In line with a general role of vitamin B6 in stress responses, low PDXK expression levels were found to be associated with poor disease outcome in two independent cohorts of patients with NSCLC. These results indicate that PDXK expression levels constitute a biomarker for risk stratification among patients with NSCLC.