This study presents a comprehensive evaluation of various computational models for glioblastoma cell classification using Raman spectroscopy data. We compare traditional machine learning methods such as support vector machines, boosting and random forests with more modern methods including convolutional neural networks, vision transformers and the broad learning system. We find that convolutional neural networks are the most successful model for this data set and perform best when some feature normalisation is performed but without preprocessing methods such as background drift removal. We also find that data augmentation did not improve performance which is contrary to other published work in the area.

The tuberous sclerosis complex (TSC)2 gene regulates the mammalian target of rapamycin (mTOR) pathway, impacting cell proliferation and growth. The loss-of-function mutations, especially in mesenchymal progenitors, drive the development multiple benign and malignant tumors. TSC2 mutations in certain cancer types, e.g., breast cancer, are also associated with poorer prognosis. The databases of TSC2-mutations report point mutations as the most prevalent. We aimed to test the feasibility of inducing point mutations in mesenchymal stem cells (MSCs), targeting the most frequent point mutations of the TSC2 gene, TSC2. c.1864 C>T (p.Arg622Trp), TSC2. c.1832 G>A (p.Arg611Glu), and TSC2. c.5024 C>T (p.Pro1675Leu) using two delivery methods for CRISPR-Cas9. We report a high editing efficiency of up to 85% inducing TSC2 point mutations in hMSCs using lipofectamine-based transfection. Overall, the high editing efficiency of some TSC2 mutations enables the induction and reversal of mutations in primary hMSCs without needing resource-consuming derivation of cell lines frequently distinct from their primary counterparts.

We depict the rare case of a patient with aneurysmatic subarachnoid hemorrhage previously treated with deep brain stimulation for Parkinson's disease. Initial CT scans showed a Fisher grade 4 subarachnoid hemorrhage with lead displacement due to midline-shift. CT angiogram revealed a supra-ophthalmic aneurysm of the internal carotid artery. The patient subsequently underwent clipping of the aneurysm and decompressive hemicraniecomy.

IntroductionPersistent spine pain syndrome type 2 (PSPS2) represents a significant burden to the individual and society. Treatment options include revision surgery, stabilisation surgery of the spine, neuromodulation, analgesics and cognitive behavioural therapy. Nevertheless, structured treatment algorithms are missing as high-level evidence on the various treatments is sparse. The aim of this study is to compare higher frequency neuromodulation with instrumentation surgery in patients suffering from PSPS2.Methods and analysisThe sPinal coRd stimulatiOn coMpared with lumbar InStrumEntation for low back pain after previous lumbar decompression (PROMISE) trial is a prospective randomised rater blinded multicentre study. Patients suffering from PSPS2 with a functional burden of Oswestry Disability Index (ODI) >20 points are randomised to treatment via spinal cord stimulation or spinal instrumentation. Primary outcome is back-related functional outcome according to the ODI 12 months after treatment. Secondary outcomes include pain perception (visual analogue scale), Short Form-36, EuroQOL5D, the amount of analgesics, the length of periprocedural hospitalisation and adverse events. Follow-up visits are planned at 3 and 12 months after treatment. Patients with previous lumbar instrumentation, symptomatic spinal stenosis, radiographical apparent spinal instability or severe psychiatric or systemic comorbidities are excluded from the study. In order to detect a significant difference of ≥10 points (ODI) with a power of 80%, n=72 patients need to be included. The recruitment period will be 24 months with a subsequent 12 months follow-up. The beginning of enrolment is planned for October 2022.Ethics and disseminationThe PROMISE trial is the first randomised rater blinded multicentre study comparing the functional effectiveness of spinal instrumentation versus neuromodulation in patients with PSPS2 in order to achieve high-level evidence for these commonly used treatment options in this severely disabling condition. Patient recruitment will be performed at regular outpatient clinic visits. No further (print, social media) publicity is planned. The study is approved by the local ethics committee (LMU Munich, Germany) and will be conducted according to the Declaration of Helsinki.Trial registration numberNCT05466110.

Introduction: Dorsal root ganglion (DRG) stimulation demonstrated superiority over traditional spinal cord stimulation with better pain relief and greater improvement of quality of life. However, leads specifically designed for DRG stimulation are difficult to implant in patients who previously underwent spinal surgery and show epidural scarring at the desired site of implantation because of the reduced stiffness of the lead. Nevertheless, recurrent leg or arm pain after spinal surgery usually manifests as a single level radiculopathy, which should theoretically be amenable to DRG stimulation. Materials and Methods: We present the percutaneous transforaminal placement of cylindrical leads through a lateral endo-scopic approach for DRG stimulation in burst mode. Results: We could successfully show that percutaneous transforaminal lead placement is feasible in three illustrative cases. Conclusion: This technical note combines two innovations, one linked to the other. The first innovation involves a novel endoscopic lateral transforaminal approach to insert a cylindrical lead to the DRG. Because this electrode is compatible with burst stimulation-enabled devices, a second innovation consists of the application of burst stimulation on the DRG.

Leksell stereotactic system-based aspiration biopsy is a common procedure in the neurosurgical treatment of deep-seated or multiple brain lesions. This study aimed to evaluate the benefit of frameless biopsy using VarioGuide compared to frame-based biopsy using the Leksell stereotactic system (LSS). We analyzed all brain biopsies using VarioGuide or LSS at our neurooncological Department of Neurosurgery in the University Hospital of Bonn between January 2018 and August 2020. We analyzed demographic data, duration of surgery, size of lesion, localization, and early complications. Uni-variable analyses were carried out on data from both groups. In total, 109 biopsies were compared (40 VarioGuide vs. 69 LSS). Patients with VarioGuide were significant older (74 (62–80) years vs. 67 (57–76) years; p = 0.03) and had a shorter duration of general anesthesia (163 (138–194) min vs. 193 (167–215) min, p < 0.001). We found no significant differences in surgery duration (VarioGuide median 28 min (IQR 20–38); LSS: median 30 min (IQR 25–39); p = 0.1352) or in early complication rates (5% vs. 7%; p = 0.644). A slightly higher false negative biopsy rate was registered in the LSS group (3 vs. 1; p = 0.1347). The size of the lesions also did not differ significantly between the two groups (18.31 ± 26.35 cm3 vs. 12.63 ± 14.62; p = 0.15). Our data showed that biopsies performed using VarioGuide took significantly less time than LSS biopsies and did not differ in complication rates. Both systems offered a high degree of patient safety.

Chronic axial lower back pain is one of the most common conditions that patients seek medical attention for in pain practices. About 15 to 40% of axial lower back pain is due to facet-mediated pain. Diagnostic blocks of the medial branch reliably identify the facet joint as the pain generator and offer a prognostic factor for response to radiofrequency neurotomy of the identified facet joints resulting in profound pain relief. However, deep brain stimulation implants have been considered a contraindication for neurotomy. We present an illustrative case of a patient with deep brain stimulation system treated with bipolar medial branch neurotomy using a two-needle technique.

Background Magnetic resonance-guided focused ultrasound of the ventral intermediate nucleus is a novel incisionless ablative treatment for essential tremor (ET). Objective The aim was to study the structural and functional network changes induced by unilateral sonication of the ventral intermediate nucleus in ET. Methods Fifteen essential tremor patients (66.2 +/- 15.4 years) underwent probabilistic tractography and functional magnetic resonance imaging (MRI) during unilateral postural tremor-eliciting tasks using 3-T MRI before, 1 month (N = 15), and 6 months (N = 10) post unilateral sonication. Results Tractography identified tract-specific alterations within the dentato-thalamo-cortical tract (DTCT) affected by the unilateral lesion after sonication. Relative to the treated hand, task-evoked activation was significantly reduced in contralateral primary sensorimotor cortex and ipsilateral cerebellar lobules IV/V and VI, and vermis. Dynamic causal modeling revealed a significant decrease in excitatory drive from the cerebellum to the contralateral sensorimotor cortex. Conclusions Thalamic lesions induced by sonication induce specific functional network changes within the DTCT, notably reducing excitatory input to ipsilateral sensorimotor cortex in ET. (c)[2022] International Parkinson and Movement Disorder Society. (c) 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society

Raman spectroscopy (RS) has been used as a powerful diagnostic and non-invasive tool in cancer diagnosis as well as in discrimination of cancer and immune cells. In this study RS in combination with chemometrics was applied to cellular Raman spectral data to distinguish the phenotype of T-cells and monocytes after incubation with media conditioned by glioblastoma stem-cells (GSCs) showing different molecular background. For this purpose, genetic modulations of epithelial-to-mesenchymal transition (EMT) process and expression of immunomodulator CD73 were introduced. Principal component analysis of the Raman spectral data showed that T-cells and monocytes incubated with tumour-conditioned media (TCMs) of GSCs with inhibited EMT activator ZEB1 or CD73 formed distinct clusters compared to controls highlighting their differences. Further discriminatory analysis performed using linear discriminant analysis (LDA) and support vector machine classification (SVM), yielded sensitivities and specificities of over 70 and 67% respectively upon validation against an independent test set. Supporting those results, flow cytometric analysis was performed to test the influence of TCMs on cytokine profile of T-cells and monocytes. We found that ZEB1 and CD73 influence T-cell and monocyte phenotype and promote monocyte differentiation into a population of mixed pro- and anti-tumorigenic macrophages (MΦs) and dendritic cells (DCs) respectively. In conclusion, Raman spectroscopy in combination with chemometrics enabled tracking T-cells and monocytes.

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.

The COVID-19 pandemic has rapidly spread all over the world and caused a major health care crisis. About 20% of patients develop severe disease and require hospitalisation, which is associated with a high mortality rate of up to 97% in those being ventilated and respiratory failure being the leading cause of death. Despite many therapeutic agents being under current investigation there is yet no panacea available. With increasing rates of infection throughout the world, there is an urgent need for new therapeutic approaches to counteract the infection. As the nervous system has shown to be a strong modulator of respiratory function and the immune response, we want to highlight pathways involved in regulation of respiratory function, the neuro-immune axis as well as the rationale for a potential targeted treatment of fulminant acute respiratory distress syndrome via transcutaneous non-invasive vagal nerve stimulation in critically-ill COVID-19 patients.

To the Editor: The COVID-19 pandemic has rapidly spread over the world. Numerous infections and fatalities have been reported in almost all countries. Facing the challenge of steadily increasing patients, limited amount of protection equipment and ventilators, resources have been relocated towards emergency departments and intensive care units. Nonemergency elective procedures such as deep brain stimulation (DBS) for patients with Parkinson's disease have been postponed. It has been discussed that most functional neurosurgery patients are vulnerable to the COVID-19 pandemic and at a higher risk for becoming critically ill infected. Therefore, most centers have halted their DBS programs. Undisputed is that hardware infections and battery replacements require urgent action to prevent sepsis, neuroinfections or akinetic crisis and death, eventually (1.Miocinovic S Ostrem JL Okun MS Bullinger KL Riva-Posse P Gross RE Buetefisch CM. Recommendations for deep brain stimulation device management during a pandemic.J Parkinsons Dis. 2020; 10 (https://doi.org/10.3233/JPD-202072.): 903-910Crossref PubMed Scopus (39) Google Scholar,2.Gross RE et al.Letter: evaluation and surgical treatment of functional neurosurgery patients with implanted deep brain stimulation and vagus nerve stimulation pulse generators during the COVID-19 pandemic.Neurosurgery. 2020; 87: E222-E226Crossref PubMed Scopus (8) Google Scholar). We would like to highlight the fact that Parkinson's disease (PD) itself is a condition with high mortality rate and complement the rationale that for any functional neurosurgery procedure, and DBS for PD in particular, we should always weigh the imminent risk of a COVID-19 infection against the long term clinical benefits of the procedure. As it remains unclear how long the pandemic will last, and if there will be a second peak, this becomes crucially important. Despite progress in medical management of PD, it does not appear to have altered the mortality rate nor significantly delayed the onset of nonmotor symptoms. Life expectancy remains decreased with the main cause of death being respiratory failure from aspiration pneumonia caused by dysphagia due to brady- or dyskinesia and rigidity of the muscles involved in the act of swallowing. Other causes of death include the deterioration of general condition, cardiovascular disease, traumatic injuries due to postural instability and sepsis. Co-evolving depression and dementia as well as the need for admittance to residential care facilities are associated with higher mortality and increased risk of suicide. All in all, 11 years is the median duration from the onset of PD until death (3.Duarte J García Olmos LM Mendoza A Clavería LE. The natural history of Parkinson's disease in the province of Segovia: mortality in a longitudinal study (20-year follow-up).Acta Neurol. Scand. 2013; 127 (https://doi.org/10.1111/ane.12003.): 295-300Crossref PubMed Scopus (28) Google Scholar). DBS of the subthalamic nucleus has become an established pillar of the therapy continuum of patients with beginning motor fluctuations and suboptimal medical management, mainly improving motor symptoms (4.Deuschl G Schade-Brittinger C Agid Y EARLYSTIM Study GroupNeurostimulation for Parkinson's disease with early motor complications.N Engl J Med. 2013; 368: 2038Google Scholar). Moreover, it has shown to improve survival rates in PD patients. A prospective, open-labeled, nonrandomized study by Ngoga et al. followed 147 patients who were offered a DBS procedure by a joint medical/surgical movement disorders clinic over the course of a 10 years period; 106 patients underwent DBS procedure whilst 41 patients prefered medical management. The mortality rate of patients who underwent DBS was significantly lower (17%) compared to patients who received medical management (41.5%), so was admittance to residential nursing care (5.7% vs. 36.6%) (5.Ngoga D Mitchell R Kausar J Hodson J Harries A Pall H. Deep brain stimulation improves survival in severe Parkinson's disease.J Neurol Neurosurg Psychiatry. 2014; 85 (https://doi.org/10.1136/jnnp-2012-304715.): 17-22Crossref PubMed Scopus (71) Google Scholar). It has been widely discussed whether improvement of survival is related to ameliorated mobility and axial motor functions, perceived improvement in swallowing ability or reduction in dopaminergic medication and drug-related side effects. DBS could prevent the development of motor complications at a much earlier time-point and before long-term sequelae occur, such as psychosocial limitations and deterioration of quality of life. Given all these factors, we strongly believe that PD patients with motor fluctuations should not be treated as nonurgent but interdisciplinary teams of neurologists and neurosurgeons should carefully balance the risk of nosocomial COVID-19 infection against the long-term survival benefits. Conflict of Interest: None for all authors. Dr. Bara developed the idea and wrote the manuscript. Prof. Maciaczyk supervised the work and performed the revisions. Both authors approved the final manuscript.

Glioblastoma (GBM) is the most aggressive malignant primary brain tumour in adulthood. Despite strong research efforts current treatment options have a limited impact on glioma stem-like cells (GSCs) which contribute to GBM formation, progression and chemoresistance. Invasive growth of GSCs is in part associated with epithelial–mesenchymal-like transition (EMT), a mechanism associated with CD73 in several cancers. Here, we show that CD73 regulates the EMT activator SNAIL1 and further investigate the role of enzymatic and non-enzymatic CD73 activity in GBM progression. Reduction of CD73 protein resulted in significant suppression of GSC viability, proliferation and clonogenicity, whereas CD73 enzymatic activity exhibited negative effects only on GSC invasion involving impaired downstream adenosine (ADO) signalling. Furthermore, application of phosphodiesterase inhibitor pentoxifylline, a potent immunomodulator, effectively inhibited ZEB1 and CD73 expression and significantly decreased viability, clonogenicity, and invasion of GSC in vitro cultures. Given the involvement of adenosine and A3 adenosine receptor in GSC invasion, we investigated the effect of the pharmacological inhibition of A3AR on GSC maintenance. Direct A3AR inhibition promoted apoptotic cell death and impaired the clonogenicity of GSC cultures. Taken together, our data indicate that CD73 is an exciting novel target in GBM therapy. Moreover, pharmacological interference, resulting in disturbed ADO signalling, provides new opportunities to innovate GBM therapy.

pandemic. With increasing numbers of infections and fatalities throughout the world and limited amounts of protection equipment and ventilators, healthcare providers have relocated resources towards emergency departments and intensive care units. Non-emergency elective procedures have been postponed. Thus, chronic pain patients are neglected which impacts life quality and expectancy and is being curbed by improper use of opioids. Consequently, it can be expected that the COVID-19 pandemic will eventually lead to a magnification of morbidity and mortality of chronic pain conditions. We conclude that chronic pain conditions should not be treated as non-urgent conditions, but that health-care professionals should feel morally and ethically obliged to offer interventional procedures and operations (be it spinal surgery or invasive neuromodulation), not in spite of the COVID-19 pandemic but because of it. Odysseus, hero of Homer’s epic opus Odyssey, once navigated through the narrow Strait of Messina between Sicily and the Italian mainland Calabria with 2 life-threatening evils within an arrow-shot of each other: On the one side of the strait there was Scylla, a vicious sea monster, on the opposite side there was Charybdis, a whirlpool, which no ship could escape. Odysseus, trying to avoid losing his entire ship to Charybdis, went too close to Scylla losing his crewmen, but eventually safeguarding the ship. Nowadays, medical professionals, like Odysseus in Homer’s tale, face 2 evils: the imminent threat of COVID-19 as well as the opioid pandemic. The goal has to be to navigate our patients through this narrow strait. The epidemic of severe acute respiratory syndrome caused by coronavirus 2 (SARSCoV-2) has rapidly spread over the world and been declared a pandemic by the World Health Organization as coronavirus disease 2019 (COVID-19) (1). Numerous infections and fatalities have been reported in almost all countries. The number of infections has increased to 4.6 millions in the United States alone with more than more than 150,000 fatalities. Worldwide numbers have reached 18 million confirmed infections and more than 688,000 fatalities as of August 3rd, 2020, with an overall mortality rate of 7% (2). Early published data indicate 25.9% of patients with SARS-CoV-2 pneumonia required intensive care unit admission and 20.1% developed acute respiratory distress syndrome, which constitutes the main cause of death (3). With no therapeutic agent available, the provision of supportive care, such as oxygenation, intubation, and mechanical ventilation, is currently the only treatment option (4). Facing the challenge of steadily increasing numbers of patients and limited amounts of protection equipment and ventilators, health-care providers have relocated resources towards emergency departments and intensive care units. Non-emergency elective procedures for patients with long-standing conditions have been postponed. COVID-19 Letter

Glioblastoma is the most aggressive type of glioma. The Wingless (Wnt) signaling pathway has been shown to promote stem cell properties and resistance to radio- and chemotherapy in glioblastoma. Here, we demonstrate that pharmacological Wnt pathway inhibition using the porcupine inhibitor LGK974 acts synergistically with temozolomide (TMZ), the chemotherapeutic drug currently used as standard treatment for glioblastoma, to suppress in vitro growth of glioma cells. Synergistic growth inhibition was independent of the O6-alkylguanine DNA alkyltransferase (MGMT) promoter methylation status. Transcriptomic analysis revealed that expression of aldehyde dehydrogenase 3A1 (ALDH3A1) was significantly down-regulated when cells were treated with LGK974 and TMZ. Suppressing ALDH3A1 expression increased the efficacy of TMZ and reduced clonogenic potential accompanied by decreased expression of stem cell markers CD133, Nestin and Sox2. Taken together, our study suggests that previous observations concerning Wnt signaling blockade to reduce chemoresistance in glioblastoma is at least in part mediated by inhibition of ALDH3A1.

Abstract Glioblastoma (GBM) is the most lethal primary malignant brain tumor with a median survival of less than two years. High levels of therapy resistance, strong cellular invasiveness and rapid cell growth demand aggressive multimodal therapies involving resection as well as radio-chemotherapy. Recent evidence has pointed to the existence of brain tumor stem cells (BTSCs), a subpopulation of human brain tumors which is thought to be responsible for tumor dissemination, relapse and chemo resistance. BTSCs have been associated with the expression of mesenchymal features as a result of epithelial-mesenchymal transition (EMT). Using high resolution proton nuclear magnetic resonance spectroscopy (1H NMR) we compared the intracellular metabolic composition of GBM cells after induction vs. inhibition of EMT as well as under stem cell or differentiated conditions. We identified that both EMT and enrichment for stemness induces the cholinic phenotype which is characterized by high intracellular levels of phosphocholine and total choline derivatives. Furthermore, interference with choline metabolism by targeting choline kinase alpha (CHKα) reversed EMT in GBM cells as we observed reduced invasiveness, clonogenicity, and expression of EMT associated genes. Taken together, interfering with choline metabolism is a powerful strategy to suppress EMT and thus target BTSCs. Moreover, the newly identified BTSC-oncometabolic network could be used to non-invasively monitor the invasive properties of glioblastomas and the success of anti-BTSC therapy. Citation Format: Katharina Koch, Rudolf Hartmann, Abigail K. Suwala, Dayana Herrera Rios, Ulf D. Kahlert, Jaroslaw Maciaczyk. Targeting brain tumor stem cells by interfering with choline metabolism: Evidence for an EMT-choline oncometabolic network [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2496. doi:10.1158/1538-7445.AM2017-2496

Glioma stem cells (GSCs) are considered to be responsible for glioblastoma’s dismal prognosis. The Wingless (WNT) signaling pathway promotes stemness and resistance towards chemo- and radiotherapy in glioblastoma. We have previously shown that pharmacological WNT inhibition using the porcupine inhibitor LGK974 reduces stem cell properties in glioblastoma in vitro. Here, we demonstrate that LGK974 acts synergistically with temozolomide (TMZ) and γ-radiation, the therapeutic modalities currently used as standard treatment for glioblastoma, to suppress in vitro growth of glioma cells. Synergistic growth inhibition was independent of the O6-alkylguanine DNA alkyltransferase (MGMT) promoter methylation status. In order to find genetic mechanisms that reveal WNT’s function in promoting chemoresistance we performed transcriptomic analysis. Aldehyde dehydrogenase 3A1 (ALDH3A1), an oxidative enzyme, was found to be significantly downregulated when cells were treated with LGK974 and TMZ. Using genetic approaches we verified a proportional correlation between WNT signaling and ALDH3A1 expression. Furthermore, ALDH3A1 knockdown cells were less viable and more sensitive towards TMZ treatment. Investigating pairs of primary and recurrent tumor samples from glioblastoma patients, we found that ALDH3A1 mRNA expression levels increased upon tumor recurrence following radiochemotherapy in some of the patients. Taken together, our study supports a novel role of ALDH3A1 in promoting TMZ resistance related to aberrant WNT signaling in glioblastoma cells.

Abstract Objective: Glioma Stem Cells (GSCs) are considered to be responsible for Glioblastoma's (GBM’s) dismal prognosis. WNT signaling is one of the major players in GSCs that promotes their radio- and chemoresistance. In this study we tested whether LGK974, an inhibitor of both canonical and non-canonical WNT signaling, might sensitize GBM cells to chemotherapeutics and irradiation and determined possible mechanisms causing treatment-resistance in GBM. Methods: At first we analyzed MGMT promoter methylation status of several GBM cell lines in order to define cells resistant to the standard chemotherapeutic drug Temozolomide (TMZ). For further investigations we chose two cell lines resistant or sensitive to TMZ, respectively. IC50 concentrations of TMZ and LGK974 as well as IC50 dose of γ-irradiation were tested via Titer Blue cell viability assay. Effectiveness of different concentration of each single therapy and its combination with LGK974 was determined to create a drug-response-curve due to the computerized simulation of synergism and antagonism in drug combination studies (Chou, 2006). A reporter assay for canonical WNT/β-catenin signaling was used to quantify the effect of TMZ and irradiation alone and in combination with LGK974 on the canonical and non-canonical WNT pathway. Western Blot and qPCR were applied to analyze the effects of combinatory therapy on protein and gene expression concerning WNT pathway activation. Results: We observed a significant synergy of combined irradiation/TMZ with LGK974 in all cell lines. There was no difference in effectiveness between cell lines resistant or sensitive to TMZ. Interestingly, following TMZ treatment or irradiation cells showed slightly decreased canonical WNT pathway activity. Furthermore, non-canonical target genes and receptors were upregulated under chemo- and radiotherapy, suggesting a reciprocal activation of the non-canonical branch of WNT signaling pathway. This phenomenon might possibly be responsible for the development of resistance against standard chemo- and radiotherapy. Conclusions: We propose that GSCs undergo a shift from canonical to non-canonical WNT signaling to become treatment-resistant under standard chemo- and radiotherapy. Treatment with LGK974 results in therapeutic synergy at least in part via suppressing the therapy-induced activation of non-canonical WNT signaling. Our results confirm the potential benefit of combining TMZ or irradiation with the WNT inhibitor LGK974 to overcome therapy-resistance in GBM. Citation Format: Abigail K. Suwala, Ulf D. Kahlert, Jaroslaw Maciaczyk. Pharmacological WNT-inhibition acts synergistically with chemo- and radiotherapy by overcoming treatment-resistance in glioma stem cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2515.

Glioblastoma (GBM) is the most malignant brain tumor and has a dismal prognosis. Aberrant WNT signaling is known to promote glioma cell growth and dissemination and resistance to conventional radio- and chemotherapy. Moreover, a population of cancer stem-like cells that promote glioma growth and recurrence are strongly dependent on WNT signaling. Here, we discuss the role and mechanisms of aberrant canonical and noncanonical WNT signaling in GBM. We present current clinical approaches aimed at modulating WNT activity and evaluate their clinical perspective as a novel treatment option for GBM.