ESTRO 36 Abstract Book

S199 ESTRO 36 2017 _______________________________________________________________________________________________

RT-PCR. Novel signalling interactions were characterised by western blotting, and a series of cell-based assays. Results Exposure to fractionated 2Gy-irradition to a cumulative total dose of 60Gy selected for 22Rv1 cells increase in clonogenic survival following irradiation (1.3 fold increase in survival after 2Gy and 2.2 fold increase after 10Gy) when compared to both parent 22Rv1 and aged-matched controls. The cross-evaluation strategy of the molecular modifications associated with a combination of radiobiological factors has identified miR-4284 as down regulated amongst radiation resistant models. Further evaluation of this miRNA indicates interaction with RLIM, RASGEF1, YB-1 and Notch-3. YB-1 inhibition with Fisetin significantly reduced clonogenic survival following irradiation, and modified Notch-3 receptor activation. Analysis of RNA extracted from a series of pooled samples from prostate cancer patients identified elevation of notch-3 mRNA levels in higher grade and hypoxic tumours. Validation in cell lines further identifies modification in Notch-3 activation following 5-Gy irradiation. Conclusion This study identifies novel molecular radiobiology that may explain the multiple effects of radiation on the molecular biology of prostate cancer cells. This work has the potential to influence future direction of suitability and treatment of radiotherapy prostate patients. PV-0372 Histology-specific quantitative mapping and targeting of glucose and glutamine metabolism in NSCLC T.W.H. Meijer 1 , P.N. Span 1 , W.J.M. Peeters 1 , R. Biemans 3 , L.F. De Geus-Oei 2 , D. Vriens 2 , L.J. Dubois 3 , J. Bussink 1 1 UMC St Radboud Nijmegen, Radiation Oncology, Nijmegen, The Netherlands 2 Leiden university medical center, Radiology, Leiden, The Netherlands 3 Maastricht University Medical Centre, Radiation Oncology, Maastricht, The Netherlands Purpose or Objective Increased glycolysis and glutamine use are related to resistance to radiotherapy. Therefore, targeting tumor cell metabolism may improve radiotherapy efficacy in NSCLC. In this prospective cohort study, we describe pharmacokinetic rate constants of 18 F-FDG metabolism (K 1 -k 3 ) and fractional blood volume (V B ) in regions with different levels of glucose metabolic rate (MR glc ) and compare these between the major NSCLC histological subtypes (adeno- (AC) and squamous cell carcinomas (SCC)). Furthermore, glycolytic rate and growth delay plus apoptotic index by glucose and/or glutamine inhibition were assessed in six NSCLC cell lines in vitro. Material and Methods One-hour dynamic 18 F-FDG-PET/CTs were acquired in 38 NSCLC patients (tumor size at least 30 mm in diameter). Parametric images of Patlak MR glc values were obtained. Lesions were delineated using the fuzzy locally adapted Bayesian (FLAB) algorithm. Tumors were divided into three equal volumes of increasing MR glc , in which K 1 -k 3 and V B were computed. For in vitro experiments, AC (H522, HCC827, H1975) and SCC (H520, H226, SW900) NSCLC cell lines were used. Glycolytic rate of cell lines was assessed by the percentage extracellular acidification rate (% ECAR) under normoxia and physiologic amount of glucose (i.e. 1.5 mM) using Seahorse. Growth delay and apoptosis analyses were performed under normoxia and 1.5 mM glucose using IncuCyte. To examine the effect of metabolic inhibition on growth delay and apoptotic index, the glycolysis inhibitor lonidamine and/or glutaminase inhibitor 968 were used. Results

In SCC compared to AC, lesion MR glc

and k 3

were

significantly higher and V B was significantly lower. AC showed less heterogeneity relative to SCC in terms of mean MR glc , k 3 and V B . In SCC, a significant higher value for k 3 and lower value for V B was found in regions with higher MR glc . Percentage ECAR under normoxic conditions was higher in AC than SCC cell lines, corresponding to the presence of 18 F-FDG metabolism in areas with high V B in AC on dynamic PET. Differences between histological subtypes were less obvious in the inhibitor experiments. All cell lines show decreased growth rate by glycolysis inhibition using lonidamine. The combination of lonidamine with the glutaminase inhibitor 968 was detrimental for cell growth. In all cell lines, except H520, apoptotic index increased using the combination therapy. Conclusion Adeno NSCLC show glycolysis under better perfused/oxygenated conditions (aerobic glycolysis) in vivo and in vitro , while SCC NSCLC exhibit anaerobic glycolysis (high glycolytic rate under poor vascularization). Apart from glucose, glutamine usage is critical for these tumors. All cell lines show a marked growth delay with increased apoptosis upon metabolic inhibition with both lonidamine and 968. Therefore, inhibiting metabolism might be a general approach to optimize treatment, especially in combination with radiotherapy in NSCLC. PV-0373 Epigenetic and metabolic reprogramming as a target for prostate tumor radiosensitization A. Dubrovska 1 , C. Peitzsch 1 , A. Tyutyunnykova 1 , M. Cojoc 1 1 OncoRay - Center for Radiation Research in Oncology, Medical Faculty Dresden Carl Gustav Carus- TU Dresden, Dresden, Germany Purpose or Objective Radiotherapy remains one of the main modalities to treat solid cancers and is one of the mainstays of curative prostate cancer treatment. Nevertheless, the risk of recurrence after radiotherapy still remains substantial in locally advanced disease. Tumor relapse after radiotherapy is attributed to the population of cancer stem cells (CSCs) which survived the treatment. Therefore, analysis of the CSC populations might be an important predictive tool of radiotherapy outcome and individualized treatment selection. However, compelling evidence suggests a high plasticity of CSCs imposed by tumor treatment. This study is aiming to investigate the interconnection of the glutamine metabolism and cancer cell plasticity in the development of tumor radioresistance for the development of new biomarkers to predict radiation treatment outcome. Material and Methods The employed methodological approaches include gene expression analysis, comparative genomic hybridization array, proteomic analysis, metabolic profiling, in vitro radiobiological clonogenic survival assays, assessment of the histone methylation marks and CSC marker expression, analysis of DNA damage repair and oxidative stress response. This study is based on the different models including tumor cell lines and their radioresistant derivatives, prostate cancer xenografts, ex vivo treated tissues and analysis of the publicly available TCGA prostate cancer datasets. Results Our study revealed that irradiation causes long-term upregulation in the expression of stem cell markers and induces tumor cell reprogramming. Furthermore, radioresistant and tumorigenic cell populations undergo a phenotypic switch during the course of radiotherapy. This phenotypic plasticity is associated with genetic, epigenetic and metabolic changes induced by irradiation. Expression of CSC markers and proteins involved in