ESTRO 36 Abstract Book

S201 ESTRO 36 _______________________________________________________________________________________________

Results In SCC compared to AC, lesion MR glc

glutamine metabolism can be used to predict clinical outcome of prostate cancer patients. Conclusion Our studies suggest that radioresistant properties of prostate cancer cells are dynamic in nature and that combination of irradiation with therapeutic agents which prevent tumor cell reprogramming and metabolic switch may restore the cytotoxic effects of irradiation in radioresistant CSC populations. References: Cojoc M et al. Cancer Res. 2015; 75(7):1482-94; Peitzsch C et al. Cancer Res. 2016; 76(9):2637-51; Kurth I et al. Oncotarget 2015; 6(33):34494-509; Krause M et al. Advanced Drug Delivery Reviews, 2016, pii: S0169-409X(16)30052-7. PV-0374 Molecular insights into a disease-relevant DNA damage response pathway B. Xu 1 1 Southern Research Institute, Molecular Radiation Biology Laboratory, Birmingham, USA Purpose or Objective The optimal DNA damage response (DDR) is critical to prevent genetic instability. The DDR is also critical to promote cellular survival in response to DNA damage as targeting optimal DDR pathways leads to sensitization to radiotherapy. The Speckle type Poz Protein (SPOP), an E3 ubiquitin ligase adaptor, has recently been identified as the gene that has the most common somatic point mutations in prostate cancer. SPOP mutations are associated with genomic alterations, indicating a role for SPOP in the maintenance of genome stability. We, and others, have recently demonstrated a critical role of SPOP in the DDR, suggesting SPOP mutants may represent a subgroup of patients that have hyper sensitivity to DNA damaging therapies. However, how SPOP mutations might impact its function and their roles in the progress of prostate tumorigenesis remain to be extensively studied. The objective of this research is to elucidate the functional significnance of SPOP in the DNA damage response pathways and to identify a subgroup of prostate cancer patients that have distinctive radiotherapeutic responses. Material and Methods Using computational modeling, we assessed the importance of the Serine 119 residue in the SBC-MATH domain. We characterized prostate cancer cells expressing the S119N dominant negative mutation using Western blot analysis, immunofluorescence microscopy, flow cytometry, and radiosensitivity by colony formation analysis. We also used in situ proximity ligation assay to demonstrate the interaction of SPOP with ATM. By mass spectrometry we identified a list of proteins that displayed alterations in association with SPOP in response to DNA damage. Results We found that Serine 119 resideing in the SBC-MATH binding interface is in close contact with non-polar residue of the SPOP-binding consensus motif. We found that prostate cancer cells expressing mutation of S119 displayed impaired DNA damage responses. Using i n situ proximity ligation assay, we demonstrate that Serine 119 is essential for SPOP interaction with ATM. We show that ATM phosphorylates SPOP on Serine 119 in response to DNA damage. Characterization of the functional significance of ATM-mediated SPOP phosphorylation indicates a wide range of downstream targets regulating cell cycle progression and DNA repair. By mass spectrometry we have identified a list of proteins that displayed alterations in association with SPOP in response to DNA damage. We found that alterations of SPOP interaction with these proteins are required for activation of the pathways involved in cell cycle checkpoints and Non-Homologous End Joining (NHEJ).

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