S2593
Radiobiology - Preclinical biomarkers
ESTRO 2026
quantitative real-time polymerase chain reaction and AR protein expression by immunohistochemical staining (anti-AR sc-7305 antibody). Proliferative activity was determined by Ki67 labeling index. Statistical analyses employed Mann–Whitney U-tests and Spearman’s rank correlations (p<0.05). Results: Tumor volumes showed wide interindividual variability, with medians of 23.7 cm ³ (T1-enhancing region) and 81.7 cm ³ (FLAIR- hyperintense region). AR mRNA levels varied substantially among samples, being higher in males and older patients, though not statistically significant. AR protein was present in both nuclei and cytoplasm, and nuclear AR expression correlated strongly with total cellular AR positivity (r=0.80, p<0.00001). Nuclear AR levels declined significantly with age (r=–0.46, p=0.03), with higher expression in patients under 60 years (p=0.0003).Tumor volume correlated directly with AR mRNA expression, showing a trend in T1-enhancing regions (r=0.41, p=0.07) and a significant association in T1-negative regions (r=0.46, p=0.04). AR protein levels, whether nuclear or cytoplasmic, showed no significant correlation with tumor volume. The Ki67 proliferation index displayed a strong trend toward positive correlation with AR mRNA expression (r=0.47, p=0.06), supporting the link between AR signaling and tumor growth. Conclusion: AR mRNA expression in GBM tissue correlates positively with tumor volume and proliferative index, suggesting its contribution to tumor expansion. Although protein-level associations were weaker, the age-related decline in nuclear AR expression highlights complex regulatory mechanisms in androgen signaling. These results indicate that AR activity may be linked to tumor growth potential and underscore its value as a potential biomarker and therapeutic target in GBM. Keywords: preoperative MRI, mRNA, protein expression
Association (NYHA) grade and serum N-terminal pro B-type natriuretic peptide (NT-proBNP) concentration. Plasma TGF- β concentration before and after RT was determined using ELISA. Allele-specific PCR was used for genotyping of TGFB1 rs1800469, rs1800470 and rs1800471. Nonparametric tests and logistic regression were used in statistical analysis. Results: There were no significant differences in plasma TGF- β 1 concentration after RT: TGF- β 1 concentration was 19.4 (13.1-28.2) ng/mL before RT and 18.5 (13.7-26.9) ng/mL after RT (P=0.106). Carriers of at least one polymorphic TGFB1 rs1800469 allele had higher plasma TGF- β 1 concentration before RT (21.9 (14.1- 31.9) ng/mL versus 18.5 (11.9-24.9) ng/mL, P=0.021). Plasma TGF- β 1 concentration before or after RT was not associated with skin or cardiac adverse events immediately after RT or after one year (all P>0.05). Conclusion: Our results suggest that TGFB1 polymorphisms may affect plasma TGF- β 1 concentration, while plasma TGF- β 1 concentration did not change immediately after RT or influence the occurrence of adverse events in DCIS patients.Grant References: ARIS J3-60064, J3-1753, J3- 2527, P1-0170 and OI-3-24. Keywords: breast cancer, radiotherapy, TGF- β Digital Poster 2091 Association Between Androgen Receptor Expression and Tumor Volume in Glioblastoma Larysa Liubych 1 , Jan Leppert 2 , Raja Hollnagel 3 , Lorenz Hahn 1 , Karolin M Streubel 1 , Deepak Ailani 3 , Harald Krenzlin 2 , Jakob Matschke 4 , Celina Soltwedel 4 , Nicole Borgardt 4 , Oksana Zemskova 5 , Claudia Ditz 2 , Naureen Keric 2 , Timo Gemoll 6 , Cedric Carl 7 , Alexander Neumann 8 , Dirk Rades 1 , Anastassia Löser 1 1 Department of Radiotherapy, University Medical Center Schleswig- Holstein, Lübeck, Germany. 2 Department of Neurosurgery, University Medical Center Schleswig-Holstein, Lübeck, Germany. 3 Department of Neurosurgery, Laboratory for Experimental Neuro- Oncology, University Medical Center Schleswig-Holstein, Lübeck, Germany. 4 Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany. 5 Department of Adjuvant Treatment for CNS Tumors, State Institution Romodanov Neurosurgery Institute, National Academy of Medical Sciences of Ukraine, Kyiv, Ukraine. 6 Department of Surgery, Section for Translational Surgical Oncology, University Medical Center Schleswig-Holstein, Lübeck, Germany. 7 Strahlentherapie Nord, Center for Radiotherapy, Bremen Gröpelingen, Bremen, Germany. 8 Department of Neuroradiology, University Medical Center Schleswig-Holstein, Lübeck, Germany Purpose/Objective: Glioblastoma (GBM) is the most aggressive primary brain tumor in adults, characterized by high invasiveness, therapy resistance, and male predominance. Tumor volume is a critical marker of aggressiveness and outcome. Emerging evidence suggests that androgen receptor (AR) signaling may influence glioma growth, yet its relationship with tumor burden remains unclear. This study investigates whether AR expression at mRNA and protein levels correlates with tumor volume and proliferative activity in GBM. Material/Methods: The cohort included 28 patients with IDH-wildtype primary GBM and nearly equal sex distribution. Preoperative magnetic resonance imaging was used to calculate tumor volumes in T1-contrast- enhancing and FLAIR-hyperintense (T1-negative) regions (BrainLab). Tumor samples were analyzed for AR mRNA expression by
Mini-Oral 2270
Aldehyde dehydrogenase-mediated mechanisms of prostate cancer therapy resistance and bone metastasis formation Ielizaveta Gorodetska 1,2 , Vasyl Lukiyanchuk 1,2 , Marta Gawin 3 , Annett Linge 1,4 , Fabian Lohaus 1,4 , Tobias Hölscher 1,4 , Monika Pietrowska 3 , Mechthild Krause 1,4 , Anna Dubrovska 1,2 1 OncoRay – National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, TUD Dresden University of Technology, Helmholtz-Zentrum Dresden- Rossendorf, Dresden, Germany. 2 Helmholtz-Zentrum Dresden- Rossendorf, Institute of Radiooncology – OncoRay, Dresden, Germany. 3 Center for Translational Research and Molecular Biology of Cancer, Maria Sklodowska-Curie National Research Institute of Oncology Gliwice Branch, Gliwice, Poland. 4 German Cancer Consortium (DKTK), Partner site Dresden, German Cancer Research Center (DKFZ), Heidelberg, Germany Purpose/Objective: Prostate cancer (PCa) is the second most common type of cancer diagnosed in men. Metastatic PCa (mPCa) has a heterogeneous response to radiotherapy (RT), and there are no biomarkers available for patient stratification. We recently identified aldehyde dehydrogenases ALDH1A1 and ALDH1A3 as critical regulators of PCa radioresistance. This study aims to delineate the mechanisms by which ALDH1 genes regulate radioresistance and metastases, and to identify associated plasma-based prognostic biomarkers. Material/Methods: The molecular mechanisms and functions were investigated by in vivo analysis, in vitro radiobiological assays, RNA and protein analysis, RNAseq, ChIP analysis, reporter assays, genetic silencing or
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