ESTRO 36 Abstract Book

S198 ESTRO 36 2017 _______________________________________________________________________________________________

To predict the potential targets of miR-200c, a microRNA database was used for bioinformatics analysis. Malignant glioma (U251), breast cancer (SKBR3, MDAMB468) and lung carcinoma (A549) cell lines were obtained from the American Type Culture Collection (ATCC, Manassas, VA, USA). Cells were transfected with pre-miR-200c or control pre-miRNA using siPORTNeoFX™ transfection reagent (Ambion, Austin, TX, USA). Anti-miR-200c was mixed with Opti-MEM (Invitrogen, Grand Island, NY, USA), incubated and added directly to cells. RT-PCR was performed using the Taqman miRNA reverse transcription kit and the Fast Real-Time PCR System (Applied Biosystems, Carlsbad, CA, USA). Clonogenic assay, immunoblotting and immunocytochemisty was perfomed. Results Ectopic overexpression of miR-200c led to down- regulation of p-AKT, p-EGFR, and p-HER2 and increased the radiosensitivity of U251, A549, SKBR3, and MDA-MB- 468 cells. In contrast, a miR-200c inhibitor led to up- regulation of p-AKT, p-EGFR, and p-HER2 and decreased radiation-induced cell killing. miR-200c led to persistent γH2AX foci formation and down-regulated pDNA-PKcs expression. Autophagy and apoptosis were major modes of cell death. Bioinformatics analysis predicted that miR-200c could have association with EGFR, AKT, MAPK, VEGFA, HIF1AN. We also confirmed that miR-200c downregulated expression of VEGF, HIF-1α, and MMP2. Overexpression of miR-200c inhibited invasion, migration, and vascular tube formation. These were associated with downregulation of E-cadherin and EphA2, and up-regulation of N-cadherin. miR-200c showed no observable cytotoxic effect on normal human fibroblasts and normal human astrocytes. Conclusion Taken together, our data suggest that miR-200c is an attractive target for improving the efficacy of radiotherapy via unique modulation of the complex regulatory network controlling cancer pro-survival signaling and EMT. PV-0371 Novel molecular radiobiology for personalised prostate cancer radiotherapy N. McDermott 1 , A. Meunier 1 , T. Jameson 2 , A. Mansour 2 , C. Haynes 2 , A. Flores 2 , A. O'Callaghan 1 , L. Marignol 1 1 Trinity Centre for Health Sciences Discipline of Radiation Therapy, Radiation Therapy, Dublin, Ireland 2 Mount Sinai School of Medicine, International Health, New York, USA Purpose or Objective The integration of tumour-specific biological parameters to the decision-making process is anticipated to overcome the recognised limitations of the current risk stratification system for prostate cancer and transform the practice of radiation oncology. Molecular imaging techniques are rapidly advancing our ability to assess the extent and aggressiveness of prostate cancer. Differential analyses of extensive genetic profiles of specimens have progressed the use of genetic signatures from tumour tissue in providing additional prognostic information. Adopting an hypothesis-based approach to the identification of novel radiobiology that can assist the personalisation of prostate radiotherapy, we propose that that the signalling pathways that regulate several cancer hallmarks and are responsive to hypoxia, such as Notch and YB-1 regulate the molecular response of cells to radiation. Material and Methods The analysis of a panel of 22Rv1 prostate cancer cells was used to support the identification of novel biomarkers of radioresistance. First, an isogenic model of radioresistance was generated in 22Rv1 prostate cancer cells through exposure to 30 x 2-Gy dose fractions. Second, radioresistance was induced in 22Rv1 cells through exposure to hypoxic conditions (0.5% O2, 24hrs). miRNA profiling of these samples was performed and validated by

Fig. 1. FDG-PET as a means to visualize and quantify early metabolic changes during VDA treatment. A: FDG-PET/MRI images showing a PBS treated (control) and an OXi4503 treated tumor-bearing mice. Arrows indicate tumor location. B: bar charts shows summarized data for all treatments using SUV or reference-tissue-based quantification of whole-tumor average or tumor sub- volume glucose metabolism. Mean values ± SD are plotted. P < 0.05; *, P < 0.001; **. C: scatterplot showing the close relationship between PET-derived and Packard-derived (ground truth) whole-tumor to whole-brain tracer ratios. D: examples of high-resolution invasive analysis of the intratumoral distribution of FDG retention. Conclusion Even though DCE-MRI and FDG-PET demonstrated significant changes after treatment with VDAs, the hyperpolarized ¹³C MRS AUC ratio and the lactate TTP did not change. Further experiments including additional tumor models and validation against established technologies are needed to explore the usefulness of hyperpolarized ¹³C MRS for early predicting of VDA efficacy. PV-0370 MicroRNA-200c radiosensitizes Human Cancer Cells with Activated EGFR or HER2-associated Signaling I.A. Kim 1 , T. Koo 2 , B. Cho 3 , E. Choi 3 , D. Lee 3 , H. Kim 3 , D. Kim 3 , J. Park 3 1 Seoul National University School of Medicine, Radiation Oncology, Seoul, Korea Republic of 2 Seoul National University Graduate School of Medicine, Radiation Oncology, Seoul, Korea Republic of 3 Seoul National Univ. Bundang Hospital, Medical Science Research Institute, Seongnam- Gyeonggi-Do, Korea Republic of Purpose or Objective A member of the miRNA-200 family, miRNA-200c (miR- 200c), recently was found to have tumor-suppressive properties by inhibiting the epithelial-mesenchymal transition (EMT) process in several cancers . miR-200c also interacts with various cellular signaling molecules and regulates many important signaling pathways. In the present study, we investigated the radiosensitizing effect of miR-200c and the mechanism of radiosensitization in a panel of human cancer cell lines. Material and Methods